1
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Braunscheidel NM, Bachhar A, Mayhall NJ. Accurate and interpretable representation of correlated electronic structure via Tensor Product Selected CI. Faraday Discuss 2024. [PMID: 39119803 DOI: 10.1039/d4fd00049h] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
The task of computing wavefunctions that are accurate, yet simple enough mathematical objects to use for reasoning, has long been a challenge in quantum chemistry. The difficulty in drawing physical conclusions from a wavefunction is often related to the generally large number of configurations with similar weights. In Tensor Product Selected Configuration Interaction (TPSCI), we use a locally correlated tensor product state basis, which has the effect of concentrating the weight of a state onto a smaller number of physically interpretable degrees of freedom. In this paper, we apply TPSCI to a series of three molecular systems ranging in separability, one of which is the first application of TPSCI to an open-shell bimetallic system. For each of these systems, we obtain accurate solutions to large active spaces, and analyze the resulting wavefunctions through a series of different approaches including (i) direct inspection of the TPS basis coefficients, (ii) construction of Bloch effective Hamiltonians, and (iii) computation of cluster correlation functions.
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Affiliation(s)
| | - Arnab Bachhar
- Department of Chemistry, Virginia Tech, Blacksburg, VA 24060, USA.
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2
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Reinhardt CR, Manetsch MT, Li WL, Román-Leshkov Y, Head-Gordon T, Kulik HJ. Computational Screening of Putative Catalyst Transition Metal Complexes as Guests in a Ga 4L 612- Nanocage. Inorg Chem 2024; 63:14609-14622. [PMID: 39049593 DOI: 10.1021/acs.inorgchem.4c02113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Metal-organic cages form well-defined microenvironments that can enhance the catalytic proficiency of encapsulated transition metal complexes (TMCs). We introduce a screening protocol to efficiently identify TMCs that are promising candidates for encapsulation in the Ga4L612- nanocage. We obtain TMCs from the Cambridge Structural Database with geometric and electronic characteristics amenable to encapsulation and mine the text of associated manuscripts to curate TMCs with documented catalytic functionality. By docking candidate TMCs inside the nanocage cavity and carrying out electronic structure calculations, we identify a subset of successfully optimized candidates (TMC-34) and observe that encapsulated guests occupy an average of 60% of the cavity volume, in line with previous observations. Notably, some guests occupy as much as 72% of the cavity as a result of linker rotation. Encapsulation has a universal effect on the electrostatic potential (ESP), systematically decreasing the ESP at the metal center of each TMC in the TMC-34 data set, while minimally altering TMC metal partial charges. Collectively these observations support geometry-based screening of potential guests and suggest that encapsulation in Ga4L612- cages could electrostatically stabilize diverse cationic or electropositive intermediates. We highlight candidate guests with associated known reactivity and solubility most amenable for encapsulation in experimental follow-up studies.
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Affiliation(s)
- Clorice R Reinhardt
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Melissa T Manetsch
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Wan-Lu Li
- Kenneth S. Pitzer Center for Theoretical Chemistry, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yuriy Román-Leshkov
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Teresa Head-Gordon
- Kenneth S. Pitzer Center for Theoretical Chemistry, Berkeley, California 94720, United States
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, United States
- Department of Bioengineering, University of California, Berkeley, California 94720, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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3
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Spitsyna NG, Lobach AS, Blagov MA, Dremova NN, Dmitriev AI, Zhidkov MV, Simonov SV. Creation of spin switching in graphene oxide-based hybrid film materials with an anionic Fe(III) 5Cl-salicyaldehyde-thiosemicarbazone complex. Dalton Trans 2024. [PMID: 39069880 DOI: 10.1039/d4dt01593b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
The present article describes the synthesis of hybrid composite film materials formed during the self-assembly process through non-covalent interactions of graphene oxide (GO) nanosheets with salt 1, represented by an anionic spin-crossover complex [FeIII(5Cl-thsa)2]- (5Cl-thsa - 5-chlorosalicylaldehyde thiosemicarbazone) and the organic tetraethylammonium cation [Et4N]+. The insertion of the salt 1 molecules into the interlayer space of GO nanosheets with the subsequent formation of a hybrid material GO-1 was observed. The film of the hybrid material GO-1 was characterized by scanning electron and confocal laser microscopy, EDX and XPS analysis, IR, Raman and 57Fe Mössbauer spectroscopy, dc magnetic measurements, and powder X-ray diffraction. Comparison of the magnetic properties of salt 1 and a film of the hybrid material GO-1 demonstrated a significant influence of the GO nanosheets matrix on the completeness of spin transition and showed a slight shift of the hysteresis loop by 1 K in the temperature range of 200-230 K. DFT calculations showed an important role of the organic cation [Et4N]+ in the process of adsorption of the spin-crossover anion [FeIII(5Cl-thsa)2]- on the GO nanosheet surface.
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Affiliation(s)
- Nataliya G Spitsyna
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Anatoly S Lobach
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Maxim A Blagov
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Nadezhda N Dremova
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Alexei I Dmitriev
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Mikhail V Zhidkov
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia.
| | - Sergei V Simonov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
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4
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Nath M, Joshi S, Mishra S. Ab initio calculation of magnetic anisotropy and thermal spin transition in the variable temperature crystal conformations of [Co(terpy) 2] 2. Phys Chem Chem Phys 2024; 26:15405-15416. [PMID: 38747204 DOI: 10.1039/d4cp00591k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
The structure-property correlation of [Co(terpy)2]2+, which shows a spin crossover at 270 K, has been computationally investigated based on its variable temperature crystal structures. Among the employed DFT functionals, only the re-parametrized hybrid B3LYP* functional could describe the correct spin transition temperature. Explicit consideration of metal-ligand sigma bonding with dynamic electron correlation is found to be necessary for an accurate determination of the SCO temperature with multi-reference calculations. The metal-ligand axial bond distances are found to be the most significant internal coordinates in deciding SCO. A small structural change along the axial distance causes a change in the t2g orbital splitting pattern and a reorientation of the magnetization axes at the SCO temperature. The complex shows an unusual triaxial magnetic anisotropy, with an easy axis of magnetization developing at higher temperatures. The strong coupling of low-frequency wagging motion of the two terpyridine ligands with the spin states of the complex provides an effective pathway for the relaxation of magnetization, resulting in a small magnetic anisotropy barrier.
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Affiliation(s)
- Moromi Nath
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
| | - Shalini Joshi
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
| | - Sabyashachi Mishra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
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5
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Hao H, Li H, Jia T, Zhou Y, Zheng X. Fano resonance in molecular junctions of spin crossover complexes. Phys Chem Chem Phys 2024; 26:12652-12660. [PMID: 38597792 DOI: 10.1039/d3cp06178g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
In this paper, we introduce a novel molecular switch paradigm that integrates spin crossover complexes with the Fano resonance effect. Specifically, by performing density-functional theory calculations, the feasibility of achieving Fano resonance using spin crossover complexes is demonstrated in our designed molecular junctions using the complex {Fe[H2B(pz)2]2[Bp(bipy)]} [pz = 1-pyrazolyl, Bp(bipy) = bis(phenylethynyl)(2,2'-bipyridine)]. It is further revealed that the Fano resonance, particularly the Fano dip, is most prominent in the junction with cobalt tips among all the schemes, together with the spin-filtering effect. Most importantly, this junction of cobalt tips is able to exhibit three distinct conductance states, which are controlled by the modulation of Fano resonance due to the spin-state transition of the complex and the applied gate voltage. Such a molecular switch paradigm holds potential for applications in logic gates, memory units, sensors, thermoelectrics, and beyond.
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Affiliation(s)
- Hua Hao
- School of Physics, Hangzhou Normal University, Hangzhou 311121, China.
| | - Honghao Li
- School of Physics, Hangzhou Normal University, Hangzhou 311121, China.
| | - Ting Jia
- School of Physics, Hangzhou Normal University, Hangzhou 311121, China.
| | - Yanhong Zhou
- College of Science, East China Jiao Tong University, Nanchang 330013, China
| | - Xiaohong Zheng
- College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
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6
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Jin H, Merz KM. Modeling Fe(II) Complexes Using Neural Networks. J Chem Theory Comput 2024; 20:2551-2558. [PMID: 38439716 PMCID: PMC10976644 DOI: 10.1021/acs.jctc.4c00063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/18/2024] [Accepted: 02/22/2024] [Indexed: 03/06/2024]
Abstract
We report a Fe(II) data set of more than 23000 conformers in both low-spin (LS) and high-spin (HS) states. This data set was generated to develop a neural network model that is capable of predicting the energy and the energy splitting as a function of the conformation of a Fe(II) organometallic complex. In order to achieve this, we propose a type of scaled electronic embedding to cover the long-range interactions implicitly in our neural network describing the Fe(II) organometallic complexes. For the total energy prediction, the lowest MAE is 0.037 eV, while the lowest MAE of the splitting energy is 0.030 eV. Compared to baseline models, which only incorporate short-range interactions, our scaled electronic embeddings improve the accuracy by over 70% for the prediction of the total energy and the splitting energy. With regard to semiempirical methods, our proposed models reduce the MAE, with respect to these methods, by 2 orders of magnitude.
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Affiliation(s)
- Hongni Jin
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Kenneth M. Merz
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Biochemistry and Molecular Biology, Michigan
State University, East Lansing, Michigan 48824, United States
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7
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Vennelakanti V, Kilic IB, Terrones GG, Duan C, Kulik HJ. Machine Learning Prediction of the Experimental Transition Temperature of Fe(II) Spin-Crossover Complexes. J Phys Chem A 2024; 128:204-216. [PMID: 38148525 DOI: 10.1021/acs.jpca.3c07104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
Spin-crossover (SCO) complexes are materials that exhibit changes in the spin state in response to external stimuli, with potential applications in molecular electronics. It is challenging to know a priori how to design ligands to achieve the delicate balance of entropic and enthalpic contributions needed to tailor a transition temperature close to room temperature. We leverage the SCO complexes from the previously curated SCO-95 data set [Vennelakanti et al. J. Chem. Phys. 159, 024120 (2023)] to train three machine learning (ML) models for transition temperature (T1/2) prediction using graph-based revised autocorrelations as features. We perform feature selection using random forest-ranked recursive feature addition (RF-RFA) to identify the features essential to model transferability. Of the ML models considered, the full feature set RF and recursive feature addition RF models perform best, achieving moderate correlation to experimental T1/2 values. We then compare ML T1/2 predictions to those from three previously identified best-performing density functional approximations (DFAs) which accurately predict SCO behavior across SCO-95, finding that the ML models predict T1/2 more accurately than the best-performing DFAs. In addition, we study ML model predictions for a set of 18 SCO complexes for which only estimated T1/2 values are available. Upon excluding outliers from this set, the RF-RFA RF model shows a strong correlation to estimated T1/2 values with a Pearson's r of 0.82. In contrast, DFA-predicted T1/2 values have large errors and show no correlation to estimated T1/2 values over the same set of complexes. Overall, our study demonstrates slightly superior performance of ML models in comparison with some of the best-performing DFAs, and we expect ML models to improve further as larger data sets of SCO complexes are curated and become available for model training.
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Affiliation(s)
- Vyshnavi Vennelakanti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Irem B Kilic
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gianmarco G Terrones
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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8
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Liu J, Sum K, Groizard T, Halet JF, Johnson SA. Theoretical and DFT Study of Atypical Pentanuclear [( iPr 3P)Ni] 5H n ( n = 4, 6, 8) Clusters: What are the Rules? Inorg Chem 2023; 62:20888-20900. [PMID: 38069675 DOI: 10.1021/acs.inorgchem.3c03335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2023]
Abstract
The structure, bonding, and properties of a series of atypical pentanuclear nickel hydride clusters supported by electron-rich iPr3P of the type [(iPr3P)Ni]5Hn (n = 4, 6, 8; H4, H6, H8) and their anionic models where iPr3P are substituted by H- (H4', H6', H8') were investigated by density functional theory (DFT) calculations. All clusters were calculated to adopt a similar square pyramidal core geometry. Calculations indicate singlet ground states with small singlet-triplet gaps for H4 and H6, similar to previously reported experimental values. Molecular orbital theory description clusters were investigated using the simplified model complexes [HNi]5Hn5- (n = 4, 6, 8; H4', H6', H8'). The results show that there are three skeletal electron pairs (SEPs) in H4'. The addition of two molecules of H2 to form H6' and H8' results in the partial or full occupation of two degenerate MOs (e* set) that give two SEPs and one SEP, respectively. Indeed, the occupation of these low-lying weakly antibonding orbitals governs the multielectron chemistry available for these clusters and plays a role in their unique reactivity.
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Affiliation(s)
- Junyang Liu
- Department of Chemistry and Biochemistry, University of Windsor, Sunset Avenue 401, Windsor, Ontario N9B 3P4, Canada
| | - Kethya Sum
- Department of Chemistry and Biochemistry, University of Windsor, Sunset Avenue 401, Windsor, Ontario N9B 3P4, Canada
| | - Thomas Groizard
- Institut des Sciences Chimiques de Rennes (ISCR)─UMR 6226, Université Rennes, CNRS, F-35000 Rennes, France
- Laboratoire de Chimie Quantique, UMR7177, Institut Le Bel, Université de Strasbourg, CNRS, 4 rue Blaise Pascal, F-67000 Strasbourg, France
| | - Jean-François Halet
- Institut des Sciences Chimiques de Rennes (ISCR)─UMR 6226, Université Rennes, CNRS, F-35000 Rennes, France
- CNRS-Saint-Gobain─NIMS, IRL 3629, Laboratory for Innovative Key Materials and Structures (LINK), National Institute for Materials Science (NIMS), Tsukuba 305-0044, Japan
| | - Samuel A Johnson
- Department of Chemistry and Biochemistry, University of Windsor, Sunset Avenue 401, Windsor, Ontario N9B 3P4, Canada
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9
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Phung QM, Nam HN, Ghosh A. Local Oxidation States in {FeNO} 6-8 Porphyrins: Insights from DMRG/CASSCF-CASPT2 Calculations. Inorg Chem 2023. [PMID: 38010736 DOI: 10.1021/acs.inorgchem.3c03689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
A first DMRG/CASSCF-CASPT2 study of a series of paradigmatic {FeNO}6, {FeNO}7, and {FeNO}8 heme-nitrosyl complexes has led to substantial new insight as well as uncovered key shortcomings of the DFT approach. By virtue of its balanced treatment of static and dynamic correlation, the calculations have provided some of the most authoritative information available to date on the energetics of low- versus high-spin states of different classes of heme-nitrosyl complexes. Thus, the calculations indicate low doublet-quartet gaps of 1-4 kcal/mol for {FeNO}7 complexes and high singlet-triplet gaps of ≳20 kcal/mol for both {FeNO}6 and {FeNO}8 complexes. In contrast, DFT calculations yield widely divergent spin state gaps as a function of the exchange-correlation functional. DMRG-CASSCF calculations also help calibrate DFT spin densities for {FeNO}7 complexes, pointing to those obtained from classic pure functionals as the most accurate. The general picture appears to be that nearly all the spin density of Fe[P](NO) is localized on the Fe, while the axial ligand imidazole (ImH) in Fe[P](NO)(ImH) pushes a part of the spin density onto the NO moiety. An analysis of the DMRG-CASSCF wave function in terms of localized orbitals and of the resulting configuration state functions in terms of resonance forms with varying NO(π*) occupancies has allowed us to address the longstanding question of local oxidation states in heme-nitrosyl complexes. The analysis indicates NO(neutral) resonance forms [i.e., Fe(II)-NO0 and Fe(III)-NO0] as the major contributors to both {FeNO}6 and {FeNO}7 complexes. This finding is at variance with the common formulation of {FeNO}6 hemes as Fe(II)-NO+ species but is consonant with an Fe L-edge XAS analysis by Solomon and co-workers. For the {FeNO}8 complex {Fe[P](NO)}-, our analysis suggests a resonance hybrid description: Fe(I)-NO0 ↔ Fe(II)-NO-, in agreement with earlier DFT studies. Vibrational analyses of the compounds studied indicate an imperfect but fair correlation between the NO stretching frequency and NO(π*) occupancy, highlighting the usefulness of vibrational data as a preliminary indicator of the NO oxidation state.
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Affiliation(s)
- Quan Manh Phung
- Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Ho Ngoc Nam
- Institute of Materials Innovation, Institutes of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
- Department of Chemical Systems Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Abhik Ghosh
- Department of Chemistry, UiT the Arctic University of Norway, N-9037 Tromsø, Norway
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10
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Radoń M. Benchmarks for transition metal spin-state energetics: why and how to employ experimental reference data? Phys Chem Chem Phys 2023; 25:30800-30820. [PMID: 37938035 DOI: 10.1039/d3cp03537a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Accurate prediction of energy differences between alternative spin states of transition metal complexes is essential in computational (bio)inorganic chemistry-for example, in characterization of spin crossover materials and in the theoretical modeling of open-shell reaction mechanisms-but it remains one of the most compelling problems for quantum chemistry methods. A part of this challenge is to obtain reliable reference data for benchmark studies, as even the highest-level applicable methods are known to give divergent results. This Perspective discusses two possible approaches to method benchmarking for spin-state energetics: using either theoretically computed or experiment-derived reference data. With the focus on the latter approach, an extensive general review is provided for the available experimental data of spin-state energetics and their interpretations in the context of benchmark studies, targeting the possibility of back-correcting the vibrational effects and the influence of solvents or crystalline environments. With a growing amount of experience, these effects can be now not only qualitatively understood, but also quantitatively modeled, providing the way to derive nearly chemically accurate estimates of the electronic spin-state gaps to be used as benchmarks and advancing our understanding of the phenomena related to spin states in condensed phases.
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Affiliation(s)
- Mariusz Radoń
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Krakow, Poland.
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11
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Manukovsky N, Kamieniarz G, Kronik L. Spin state and magnetic coupling in polynuclear Ni(II) complexes from density functional theory: is there an optimal amount of Fock exchange? J Chem Phys 2023; 159:154103. [PMID: 37846951 DOI: 10.1063/5.0169105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 09/25/2023] [Indexed: 10/18/2023] Open
Abstract
Reliable prediction of the ground-state spin and magnetic coupling constants in transition-metal complexes is a well-known challenge for density functional theory (DFT). One popular strategy for addressing this long-standing issue involves the modification of the fraction of Fock exchange in a hybrid functional. Here we explore the viability of this approach using three polynuclear metal-organic complexes based on a Ni4O4 cubane motif, having different ground state spin values (S = 0, 2, 4) owing to the use of different ligands. We systematically search for an optimum fraction of Fock exchange, across various global, range-separated, and double hybrid functionals. We find that for all functionals tested, at best there only exists a very narrow range of Fock exchange fractions which results in a correct prediction of the ground-state spin for all three complexes. The useful range is functional dependent, but general trends can be identified. Typically, at least two similar systems must be used in order to determine both an upper and lower limit of the optimal range. This is likely owing to conflicting demands of minimizing delocalization errors, which typically requires a higher percentage of Fock exchange, and addressing static correlation, which typically requires a lower one. Furthermore, we find that within the optimal range of Fock exchange, the sign and relative magnitude of Ni-Ni magnetic coupling constants are reasonably well reproduced, but there is still room for quantitative improvement in the prediction. Thus, the prediction of spin state and magnetic coupling in polynuclear complexes remains an ongoing challenge for DFT.
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Affiliation(s)
- Nurit Manukovsky
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth 7610001, Israel
| | | | - Leeor Kronik
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovoth 7610001, Israel
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12
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Sánchez-de-Armas R, Jaber El Lala I, Calzado CJ. How complex-surface interactions modulate the spin transition of Fe(II) SCO complexes supported on metallic surfaces? Phys Chem Chem Phys 2023; 25:21673-21683. [PMID: 37551593 DOI: 10.1039/d3cp02539j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
The deposition of a prototypical spin-crossover [Fe(phen)2(NCS)2] complex on Au(111), Cu(111) and Ag(111) surfaces has been investigated by means of periodic DFT+U calculations, with the aim of understanding how different metallic surfaces affect the spin state switching. Our results show that adsorption is metal- and spin-dependent, with different preferred adsorption sites for the different surfaces and spin states. For the three considered surfaces adsorption energies are larger in the LS state than in the HS one, which increases the transition enthalpy by 58.7 kJ mol-1 for Cu(111), 14.6 kJ mol-1 for Au(111) and 9.6 kJ mol-1 for Ag(111) with respect to the free molecule. There is a clear correlation between this effect and the extent of the complex-surface interaction, which can be established from adsorption energies, surface-complex distances and charge density difference plots as: Cu(111) > Au(111) > Ag(111). Therefore, a stronger interaction with the surface produces a larger energy difference between two spin states, making the spin transition less probable to occur. Finally, our calculations show that it would be possible to probe the spin-state of the deposited molecules from the STM images, in line with the recent experimental results.
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Affiliation(s)
- Rocío Sánchez-de-Armas
- Departamento de Química Física, Universidad de Sevilla, C. Prof. García González, s/n, 41012, Spain.
| | - Iman Jaber El Lala
- Departamento de Química Física, Universidad de Sevilla, C. Prof. García González, s/n, 41012, Spain.
| | - Carmen J Calzado
- Departamento de Química Física, Universidad de Sevilla, C. Prof. García González, s/n, 41012, Spain.
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13
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Martínez Serra A, Dhingra A, Asensio MC, Real JA, Francisco Sánchez Royo J. Is the surface of Hofmann-like spin-crossover {Fe(pz)[Pt(CN) 4]} the same as its bulk? Dalton Trans 2023; 52:10305-10309. [PMID: 37469273 DOI: 10.1039/d3dt01955a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Temperature dependent X-ray photoemission spectroscopy (XPS) has been employed to examine the spin-crossover (SCO) transition in the nanocrystals of 3D Hoffman-like {Fe(pz)[Pt(CN)4]}. Consistent with the existing literature, the temperature-dependent variations in the Fe 2p core-level spectrum provide unambiguous evidence of the spin-state transition in this SCO complex. One of the many possible reasons behind a lack of discernible temperature-driven shifts in the binding energies of both the N 1s core-level components could be the immunity of its HS electronic configuration to thermal fluctuations. The high-spin fraction versus temperature plot, extrapolated from the XPS measurements, reveals that the surface of the nanocrystals of {Fe(pz)[Pt(CN)4]} is in the high-spin state at room temperature, rendering it promising for room-temperature spintronics and quantum information science applications.
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Affiliation(s)
- Alejandro Martínez Serra
- Institut de Ciència dels Materials de la Universitat de València (ICMUV), University of Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, 46980 Paterna, Valencia, Spain.
| | - Archit Dhingra
- Institut de Ciència dels Materials de la Universitat de València (ICMUV), University of Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, 46980 Paterna, Valencia, Spain.
| | - María Carmen Asensio
- Materials Science Institute of Madrid (ICMM/CSIC), Cantoblanco, E-28049 Madrid, Spain
- MATINÉE, the CSIC Associated Unit between the Materials Science Institute (ICMUV) and the ICMM, Cantoblanco, E-28049 Madrid, Spain
| | - José Antonio Real
- Institut de Ciència Molecular (ICMol), University of Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, 46980 Paterna, Valencia, Spain
| | - Juan Francisco Sánchez Royo
- Institut de Ciència dels Materials de la Universitat de València (ICMUV), University of Valencia, Carrer del Catedrátic José Beltrán Martinez, 2, 46980 Paterna, Valencia, Spain.
- MATINÉE, the CSIC Associated Unit between the Materials Science Institute (ICMUV) and the ICMM, Cantoblanco, E-28049 Madrid, Spain
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14
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Joshi S, Roy Chowdhury S, Mishra S. Spin-state energetics and magnetic anisotropy in penta-coordinated Fe(III) complexes with different axial and equatorial ligand environments. Phys Chem Chem Phys 2023. [PMID: 37367302 DOI: 10.1039/d3cp02182c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
The penta-coordinated trigonal-bi-pyramidal (TBP) Fe(III) complex (PMe2Ph)2FeCl3 shows a reduced magnetic anisotropy in its intermediate-spin (IS) state as compared to its methyl-analog (PMe3)2Fe(III)Cl3. In this work, the ligand environment in (PMe2Ph)2FeCl3 is systematically altered by replacing the axial -P with -N and -As, the equatorial -Cl with other halides, and the axial methyl group with an acetyl group. This has resulted in a series of Fe(III) TBP complexes modelled in their IS and high-spin (HS) states. Lighter ligands -N and -F stabilize the complex in the HS state, while the magnetically anisotropic IS state is stabilized by -P and -As at the axial site, and -Cl, -Br, and -I at the equatorial site. Larger magnetic anisotropies appear for complexes with nearly degenerate ground electronic states that are well separated from the higher excited states. This requirement, largely controlled by the d-orbital splitting pattern due to the changing ligand field, is achieved with a certain combination of axial and equatorial ligands, such as -P and -Br, -As and -Br, and -As and -I. In most cases, the acetyl group at the axial site enhances the magnetic anisotropy compared to its methyl counterpart. In contrast, the presence of -I at the equatorial site compromises the uniaxial type of anisotropy of the Fe(III) complex leading to an enhanced rate of quantum tunneling of magnetization.
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Affiliation(s)
- Shalini Joshi
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
| | | | - Sabyashachi Mishra
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
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15
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Huss T, Dixon IM. Electronic Structure and Geometry of the Lowest 2LMCT State of Fe(III) Potential Fluorescent Emitters†. Inorg Chem 2023; 62:4284-4290. [PMID: 36852931 DOI: 10.1021/acs.inorgchem.2c04407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
Metal complexes with a 3d6 electron count are emerging as an alternative to 4d6-based photosensitizers, emitters, or photoredox catalysts. In recent years, several Fe(II) potential emitters have been proposed, based on strongly donating ligand sets. Those tend to facilitate oxidation to their 3d5 species, whose photophysics is based on low-lying ligand-to-metal charge-transfer (LMCT) states. The geometry and electronic structure of 2LMCT states are unveiled in this work.
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Affiliation(s)
- Tabea Huss
- Laboratoire de Chimie et Physique Quantiques, Universite de Toulouse, CNRS, Universite Toulouse III - Paul Sabatier, F-31062 Toulouse, France
| | - Isabelle M Dixon
- Laboratoire de Chimie et Physique Quantiques, Universite de Toulouse, CNRS, Universite Toulouse III - Paul Sabatier, F-31062 Toulouse, France
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16
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Romero S, Baruah T, Zope RR. Spin-state gaps and self-interaction-corrected density functional approximations: Octahedral Fe(II) complexes as case study. J Chem Phys 2023; 158:054305. [PMID: 36754787 DOI: 10.1063/5.0133999] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Accurate prediction of a spin-state energy difference is crucial for understanding the spin crossover phenomena and is very challenging for density functional approximations, especially for local and semi-local approximations due to delocalization errors. Here, we investigate the effect of the self-interaction error removal from the local spin density approximation (LSDA) and Perdew-Burke-Ernzerhof generalized gradient approximation on the spin-state gaps of Fe(II) complexes with various ligands using recently developed locally scaled self-interaction correction (LSIC) by Zope et al. [J. Chem. Phys. 151, 214108 (2019)]. The LSIC method is exact for one-electron density, recovers the uniform electron gas limit of the underlying functional, and approaches the well-known Perdew-Zunger self-interaction correction (PZSIC) as a particular case when the scaling factor is set to unity. Our results, when compared with reference diffusion Monte Carlo results, show that the PZSIC method significantly overestimates spin-state gaps favoring low spin states for all ligands and does not improve upon density functional approximations. The perturbative LSIC-LSDA using PZSIC densities significantly improves the gaps with a mean absolute error of 0.51 eV but slightly overcorrects for the stronger CO ligands. The quasi-self-consistent LSIC-LSDA, such as coupled-cluster single double and perturbative triple [CCSD(T)], gives a correct sign of spin-state gaps for all ligands with a mean absolute error of 0.56 eV, comparable to that of CCSD(T) (0.49 eV).
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Affiliation(s)
- Selim Romero
- Computational Science Program, The University of Texas at El Paso, El Paso, Texas 79968, USA
| | - Tunna Baruah
- Department of Physics, University of Texas at El Paso, El Paso, Texas 79968, USA
| | - Rajendra R Zope
- Department of Physics, University of Texas at El Paso, El Paso, Texas 79968, USA
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17
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Blagov MA, Spitsyna NG, Ovanesyan NS, Lobach AS, Zorina LV, Simonov SV, Zakharov KV, Vasiliev AN. First crystal structure of an Fe(III) anionic complex based on a pyruvic acid thiosemicarbazone ligand with Li +: synthesis, features of magnetic behavior and theoretical analysis. Dalton Trans 2023; 52:1806-1819. [PMID: 36661046 DOI: 10.1039/d2dt03630d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The iron(III) anionic complex based on a pyruvic acid thiosemicarbazone ligand with the lithium cation Li[FeIII(thpy)2]·3H2O (1) has been synthesized and characterized by FTIR spectroscopy, powder and single crystal X-ray diffraction, direct current magnetic susceptibility measurements, and 57Fe Mössbauer spectroscopy. Moreover, the molecular structure of the [Fe(thpy)2]- anion has been determined for the first time. The [Fe(thpy)2]- units in the triclinic P1̄ lattice of 1 are assembled into layers parallel to the bc plane. The Li+ cations and water molecules are located between the layers and the structure is stabilized by hydrogen bonding. The [Fe(thpy)2]- anions form interconnected dimer pairs through hydrogen bonds and short contacts with Fe⋯Fe separation of 6.7861(4) Å. According to dc magnetic measurements, compound 1 demonstrates an incipient spin-crossover transition from the LS (S = 1/2) to the HS (S = 5/2) state above 250 K. The Bleaney-Bowers equation for a model of an isolated LS dimer with a mean-field correction was applied to fit the experimental data of magnetic susceptibility dependence on temperature in the temperature range of 2-250 K. The intra-dimer J1 = -1.79(1) K and inter-dimer J2 = -0.24(3) K antiferromagnetic coupling constants were defined. The analysis of the 57Fe Mössbauer spectra at 80 K and 296 K confirms the presence of the shortened distances between the iron nuclei. Moreover, the influence of the lithium cation on the stabilization of the LS state was shown for the [Fe(thpy)2]- anion. BS-DFT calculations for the optimized structure of two isolated [Fe(thpy)2]- anions also correctly predict a weak exchange J1(calc) = -0.92 K. DFT calculations revealed the OPBE (GGA-type) functional that correctly predicts the spin-crossover transition for the iron(III) thpy compounds. Besides, the effect of the N2O4, N2S2O2, and N2Se2O2 coordination environments on the energy stabilization of the LS state of iron(III) anionic thpy complexes was noted as well.
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Affiliation(s)
- Maxim A Blagov
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia.,Lomonosov Moscow State University, Moscow 119991, Russia
| | - Nataliya G Spitsyna
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia
| | - Nikolai S Ovanesyan
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia
| | - Anatolii S Lobach
- Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia
| | - Leokadiya V Zorina
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia.
| | - Sergey V Simonov
- Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka, Moscow region 142432, Russia.
| | | | - Alexander N Vasiliev
- Lomonosov Moscow State University, Moscow 119991, Russia.,National University of Science and Technology "MISiS", Moscow 119049, Russia
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18
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Montenegro-Pohlhammer N, Kuppusamy SK, Cárdenas-Jirón G, Calzado CJ, Ruben M. Computational demonstration of isomer- and spin-state-dependent charge transport in molecular junctions composed of charge-neutral iron(II) spin-crossover complexes. Dalton Trans 2023; 52:1229-1240. [PMID: 36606462 DOI: 10.1039/d2dt02598a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Chemistry offers a multitude of opportunities towards harnessing functional molecular materials with application propensity. One emerging area of interest is molecular spintronics, in which charge and spin degrees of freedom have been used to achieve power-efficient device architectures. Herein, we show that, with the aid of state-of-the-art quantum chemical calculations on designer molecular junctions, the conductance and spin filtering capabilities are molecular structure-dependent. As inferred from the calculations, structural control over the transport can be achieved by changing the position of the thiomethyl (SMe) anchoring groups for Au(111) electrodes in a set of isomeric 2,2'-bipyridine-based metal coordinating ligand entities L1 and L2. The computational studies on heteroleptic iron(II) coordination complexes (1 and 2) composed of L1 and L2 reveal that switching the spin-state of the iron(II) centers, from the low-spin (LS) to high-spin (HS) state, by means of an external electric field stimulus, could, in theory, be performed. Such switching, known as spin-crossover (SCO), renders charge transport through single-molecule junctions of 1 and 2 spin-state-dependent, and the HS junctions are more conductive than the LS junctions for both complexes. Additionally, the LS and HS junctions based on complex 1 are more conductive than those featuring complex 2. Moreover, it is predicted that the spin filtering efficiency (SFE) of the HS junctions strongly depends on the bridging complex geometry, with 1 showing a voltage-dependent SFE, whereas 2 exhibits an SFE of practically 100% over all the studied voltage range. To be pragmatic towards applications, the ligands L1 and L2 and complex 1 have been successfully synthesized, and the spin-state switching propensity of 1 in the bulk state has been elucidated. The results shown in this study might lead to the synthesis and characterization of isomeric SCO complexes with tuneable spin-state switching and charge transport properties.
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Affiliation(s)
- Nicolás Montenegro-Pohlhammer
- Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile (USACH), 9170022, Santiago, Chile.
- Departamento de Química Física. Universidad de Sevilla, c/Profesor García González, s/n., 41012 Sevilla, Spain
| | - Senthil Kumar Kuppusamy
- Institute of Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
| | - Gloria Cárdenas-Jirón
- Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile (USACH), 9170022, Santiago, Chile.
| | - Carmen J Calzado
- Departamento de Química Física. Universidad de Sevilla, c/Profesor García González, s/n., 41012 Sevilla, Spain
| | - Mario Ruben
- Institute of Quantum Materials and Technologies (IQMT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Centre Européen de Sciences Quantiques (CESQ), Institut de Science et d'Ingénierie Supramoléculaire (ISIS), Université de Strasbourg, Strasbourg, France
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19
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Duan C, Nandy A, Meyer R, Arunachalam N, Kulik HJ. A transferable recommender approach for selecting the best density functional approximations in chemical discovery. NATURE COMPUTATIONAL SCIENCE 2023; 3:38-47. [PMID: 38177951 DOI: 10.1038/s43588-022-00384-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 11/23/2022] [Indexed: 01/06/2024]
Abstract
Approximate density functional theory has become indispensable owing to its balanced cost-accuracy trade-off, including in large-scale screening. To date, however, no density functional approximation (DFA) with universal accuracy has been identified, leading to uncertainty in the quality of data generated from density functional theory. With electron density fitting and Δ-learning, we build a DFA recommender that selects the DFA with the lowest expected error with respect to the gold standard (but cost-prohibitive) coupled cluster theory in a system-specific manner. We demonstrate this recommender approach on the evaluation of vertical spin splitting energies of transition metal complexes. Our recommender predicts top-performing DFAs and yields excellent accuracy (about 2 kcal mol-1) for chemical discovery, outperforming both individual Δ-learning models and the best conventional single-functional approach from a set of 48 DFAs. By demonstrating transferability to diverse synthesized compounds, our recommender potentially addresses the accuracy versus scope dilemma broadly encountered in computational chemistry.
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Affiliation(s)
- Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ralf Meyer
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Naveen Arunachalam
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
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20
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Reimann M, Kaupp M. Spin-State Splittings in 3d Transition-Metal Complexes Revisited: Benchmarking Approximate Methods for Adiabatic Spin-State Energy Differences in Fe(II) Complexes. J Chem Theory Comput 2022; 18:7442-7456. [PMID: 36417564 DOI: 10.1021/acs.jctc.2c00924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The CASPT2+δMRCI composite approach reported in a companion paper has been extended and used to provide high-quality reference data for a series of adiabatic spin gaps (defined as ΔE = Equintet - Esinglet) of [FeIIL6]2+ complexes (L = CNH, CO, NCH, NH3, H2O), either at nonrelativistic level or including scalar relativistic effects. These highly accurate data have been used to evaluate the performance of various more approximate methods. Coupled-cluster theory with singles, doubles, and perturbative triples, CCSD(T), is found to agree well with the new reference data for Werner-type complexes but exhibits larger underestimates by up to 70 kJ/mol for the π-acceptor ligands, due to appreciable static correlation in the low-spin states of these systems. Widely used domain-based local CCSD(T) calculations, DLPNO-CCSD(T), are shown to depend very sensitively on the cutoff values used to construct the localized domains, and standard values are not sufficient. A large number of density functional approximations have been evaluated against the new reference data. The B2PLYP double hybrid gives the smallest deviations, but several functionals from different rungs of the usual ladder hierarchy give mean absolute deviations below 20 kJ/mol. This includes the B97-D semilocal functional, the PBE0* global hybrid with 15% exact-exchange admixture, as well as the local hybrids LH07s-SVWN and LH07t-SVWN. Several further functionals achieve mean absolute errors below 30 kJ/mol (M06L-D4, SSB-D, B97-1-D4, LC-ωPBE-D4, LH12ct-SsirPW92-D4, LH12ct-SsifPW92-D4, LH14t-calPBE-D4, LHJ-HFcal-D4, and several further double hybrids) and thereby also still overall outperform CCSD(T) or uncorrected CASPT2. While exact-exchange admixture is a crucial factor in favoring high-spin states, the present evaluations confirm that other aspects can be important as well. A number of the better-performing functionals underestimate the spin gaps for the π-acceptor ligands but overestimate them for L = NH3, H2O. In contrast to a previous suggestion, non-self-consistent density functional theory (DFT) computations on top of Hartree-Fock orbitals are not a promising path to produce accurate spin gaps in such complexes.
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Affiliation(s)
- Marc Reimann
- Technische Universität Berlin, Institut für Chemie, Theoretische Chemie/Quantenchemie, Sekr. C7, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Martin Kaupp
- Technische Universität Berlin, Institut für Chemie, Theoretische Chemie/Quantenchemie, Sekr. C7, Straße des 17. Juni 135, D-10623 Berlin, Germany
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21
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Dey B, Mehta S, Mondal A, Cirera J, Colacio E, Chandrasekhar V. Push and Pull Effect of Methoxy and Nitro Groups Modifies the Spin-State Switching Temperature in Fe(III) Complexes. ACS OMEGA 2022; 7:39268-39279. [PMID: 36340084 PMCID: PMC9631739 DOI: 10.1021/acsomega.2c05380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
We have explored the impact of electron-donating (methoxy) and electron-withdrawing (nitro) substituents on SalEen ligand based spin crossover (SCO) behavior of Fe(III) complexes. Thus, 3-X-substituted SalEen ligands were employed to prepare [Fe(3-X-SalEen)2]·NCSe, where X = OMe (1), H (2), and NO2 (3) (3-X-SalEen is the condensation product of 3-substituted salicylaldehyde and N-ethylethylenediamine). The characteristic spin transition temperature (T 1/2) is shown to shift to a lower temperature when an electron-donating substituent (OMe) is used and to a higher temperature when an electron-withdrawing substituent (NO2) is used. We used experimental and theoretical methods to determine the reasons for this behavior. The solid-state magnetic data revealed the transition temperatures for complexes 1, 2, and 3 to be 219, 251, and 366 K, respectively. The solution-state magnetic data also support this trend in T 1/2 values. UV-vis spectra analysis indicates that there is greater delocalization in the π-manifold of the ligand when the nitro group is the substituent. Theoretical studies through density functional theory methods suggest the methoxy substituent decreases the energy gap between the t2g and eg orbitals (explaining the lower T 1/2 value), while the nitro substituent increases the energy gap between the t2g and eg orbitals and thus increases the T 1/2 value.
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Affiliation(s)
- Bijoy Dey
- Tata
Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad500107, India
| | - Sakshi Mehta
- Solid
State and Structural Chemistry Unit, Indian
Institute of Science, Sir C V Raman Road, Bangalore, Karnataka560012, India
| | - Abhishake Mondal
- Solid
State and Structural Chemistry Unit, Indian
Institute of Science, Sir C V Raman Road, Bangalore, Karnataka560012, India
| | - Jordi Cirera
- Departament
de Química Inorgànica i Orgànica and Institut
de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028Barcelona, Spain
| | - Enrique Colacio
- Departamento
de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071Granada, Spain
| | - Vadapalli Chandrasekhar
- Tata
Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad500107, India
- Department
of Chemistry, Indian Institute of Technology
Kanpur, Kanpur, Uttar Pradesh208016, India
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22
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Mirzanejad A, Varganov SA. The role of the intermediate triplet state in iron-catalyzed multi-state C-H activation. Phys Chem Chem Phys 2022; 24:20721-20727. [PMID: 36018581 DOI: 10.1039/d2cp02733j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficient activation and functionalization of the C-H bond under mild conditions are of a great interest in chemical synthesis. We investigate the previously proposed spin-accelerated activation of the C(sp2)-H bond by a Fe(II)-based catalyst to clarify the role of the intermediate triplet state in the reaction mechanism. High-level electronic structure calculations on a small model of a catalytic system utilizing the coupled cluster with the single, double, and perturbative triple excitations [CCSD(T)] are used to select the density functional for the full-size model. Our analysis indicates that the previously proposed two-state quintet-singlet reaction pathway is unlikely to be efficient due to a very weak spin-orbit coupling between these two spin states. We propose a more favorable multi-state quintet-triplet-singlet reaction pathway and discuss the importance of the intermediate triplet state. This triplet state facilitates a spin-accelerated reaction mechanism by strongly coupling to both quintet and singlet states. Our calculations show that the C-H bond activation through the proposed quintet-triplet-singlet reaction pathway is more thermodynamically favorable than the single-state quintet and two-state singlet-quintet mechanisms.
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Affiliation(s)
- Amir Mirzanejad
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557-0216, USA.
| | - Sergey A Varganov
- Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557-0216, USA.
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23
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Francis S, Rice CR, Scattergood PA, Elliott PIP. Synthesis and characterisation of group 8 tris(1-benzyl-1,2,3-triazol-4-yl)- p-anisolylmethane complexes. Dalton Trans 2022; 51:13692-13702. [PMID: 36001010 DOI: 10.1039/d2dt02503e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The tris(1,2,3-triazol-4-yl)methane framework offers a highly versatile architecture for ligand design, yet the coordination chemistry of this class of ligand remains largely unexplored. We report here the synthesis and characterisation of the homoleptic complexes [M(ttzm)2](PF6)2 (ttzm = tris(1-benzyl-1,2,3-triazol-4-yl)-p-anisolylmethane; M = Fe (Fe), Ru (Ru), Os (Os)). Initial attempts to prepare Ru by reaction of [Ru(p-cymene)Cl2]2 and ttzm also led to the isolation of the heteroleptic complex [Ru(p-cymene)(ttzm)](PF6)2. The structures of [Ru(p-cymene)(ttzm)](PF6)2, [Fe(ttzm)2]2+ (as its BPh4- salt) and Os were solved by X-ray diffraction. The homoleptic Fe(II) and Os(II) containing cations adopt distorted octahedral geometries due to the steric interactions between the ansiole and triazole rings of the ttzm ligands. The homoleptic complexes all adopt a low-spin d6 configuration and exhibit reversible M(II)/M(III) processes (+0.35 to +0.72 V vs. Fc/Fc+). These oxidation processes are cathodically shifted relative to those of related hexatriazole donor based complexes with density functional theory (DFT) calculations showing the metal d-orbitals are destabilised through a π-donor contribution from the triazole rings. The complexes all show prominent UV-visible absorption bands between 350 and 450 nm assigned to transitions of 1MLCT character. Whilst none of the homoleptic complexes are emissive in room temperature fluid solutions, Os is emissive at 77 K in an EtOH/MeOH glass (λmax 472 nm).
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Affiliation(s)
- Samuel Francis
- Department of Chemical Sciences & Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK.
| | - Craig R Rice
- Department of Chemical Sciences & Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK.
| | - Paul A Scattergood
- Department of Chemical Sciences & Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK.
| | - Paul I P Elliott
- Department of Chemical Sciences & Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK.
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24
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Unsleber JP, Grimmel SA, Reiher M. Chemoton 2.0: Autonomous Exploration of Chemical Reaction Networks. J Chem Theory Comput 2022; 18:5393-5409. [PMID: 35926118 DOI: 10.1021/acs.jctc.2c00193] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fueled by advances in hardware and algorithm design, large-scale automated explorations of chemical reaction space have become possible. Here, we present our approach to an open-source, extensible framework for explorations of chemical reaction mechanisms based on the first-principles of quantum mechanics. It is intended to facilitate reaction network explorations for diverse chemical problems with a wide range of goals such as mechanism elucidation, reaction path optimization, retrosynthetic path validation, reagent design, and microkinetic modeling. The stringent first-principles basis of all algorithms in our framework is key for the general applicability that avoids any restrictions to specific chemical systems. Such an agile framework requires multiple specialized software components of which we present three modules in this work. The key module, Chemoton, drives the exploration of reaction networks. For the exploration itself, we introduce two new algorithms for elementary-step searches that are based on Newton trajectories. The performance of these algorithms is assessed for a variety of reactions characterized by a broad chemical diversity in terms of bonding patterns and chemical elements. Chemoton successfully recovers the vast majority of these. We provide the resulting data, including large numbers of reactions that were not included in our reference set, to be used as a starting point for further explorations and for future reference.
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Affiliation(s)
- Jan P Unsleber
- Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Stephanie A Grimmel
- Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Markus Reiher
- Laboratorium für Physikalische Chemie, ETH Zürich, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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25
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Fluorescence emission modulation in cyanido-bridged Fe(II) spin crossover coordination polymers. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1294-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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26
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Csizi K, Eckert L, Brunken C, Hofstetter TB, Reiher M. The Apparently Unreactive Substrate Facilitates the Electron Transfer for Dioxygen Activation in Rieske Dioxygenases. Chemistry 2022; 28:e202103937. [PMID: 35072969 PMCID: PMC9306888 DOI: 10.1002/chem.202103937] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Indexed: 12/29/2022]
Abstract
Rieske dioxygenases belong to the non-heme iron family of oxygenases and catalyze important cis-dihydroxylation as well as O-/N-dealkylation and oxidative cyclization reactions for a wide range of substrates. The lack of substrate coordination at the non-heme ferrous iron center, however, makes it particularly challenging to delineate the role of the substrate for productive O 2 activation. Here, we studied the role of the substrate in the key elementary reaction leading to O 2 activation from a theoretical perspective by systematically considering (i) the 6-coordinate to 5-coordinate conversion of the non-heme FeII upon abstraction of a water ligand, (ii) binding of O 2 , and (iii) transfer of an electron from the Rieske cluster. We systematically evaluated the spin-state-dependent reaction energies and structural effects at the active site for all combinations of the three elementary processes in the presence and absence of substrate using naphthalene dioxygenase as a prototypical Rieske dioxygenase. We find that reaction energies for the generation of a coordination vacancy at the non-heme FeII center through thermoneutral H2 O reorientation and exothermic O 2 binding prior to Rieske cluster oxidation are largely insensitive to the presence of naphthalene and do not lead to formation of any of the known reactive Fe-oxygen species. By contrast, the role of the substrate becomes evident after Rieske cluster oxidation and exclusively for the 6-coordinate non-heme FeII sites in that the additional electron is found at the substrate instead of at the iron and oxygen atoms. Our results imply an allosteric control of the substrate on Rieske dioxygenase reactivity to happen prior to changes at the non-heme FeII in agreement with a strategy that avoids unproductive O 2 activation.
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Affiliation(s)
- Katja‐Sophia Csizi
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Lina Eckert
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Christoph Brunken
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Thomas B. Hofstetter
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
| | - Markus Reiher
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
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27
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Pápai M. Toward Simulation of Fe(II) Low-Spin → High-Spin Photoswitching by Synergistic Spin-Vibronic Dynamics. J Chem Theory Comput 2022; 18:1329-1339. [PMID: 35199532 PMCID: PMC8908767 DOI: 10.1021/acs.jctc.1c01184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
A new theoretical
approach is presented and applied for the simulation
of Fe(II) low-spin (LS, singlet, t2g6eg0) → high-spin (HS, quintet, t2g4eg2) photoswitching dynamics of the octahedral
model complex [Fe(NCH)6]2+. The utilized synergistic
methodology heavily exploits the strengths of complementary electronic
structure and spin-vibronic dynamics methods. Specifically, we perform
3D quantum dynamics (QD) and full-dimensional trajectory surface hopping
(TSH, in conjunction with a linear vibronic coupling model), with
the modes for QD selected by TSH. We follow a hybrid approach which
is based on the application of time-dependent density functional theory
(TD-DFT) excited-state potential energy surfaces (PESs) and multiconfigurational
second-order perturbation theory (CASPT2) spin–orbit couplings
(SOCs). Our method delivers accurate singlet–triplet–quintet
intersystem crossing (ISC) dynamics, as assessed by comparison to
our recent high-level ab initio simulations and related
time-resolved experimental data. Furthermore, we investigate the capability
of our simulations to identify the location of ISCs. Finally, we assess
the approximation of constant SOCs (calculated at the Franck–Condon
geometry), whose validity has central importance for the combination
of TD-DFT PESs and CASPT2 SOCs. This efficient methodology will have
a key role in simulating LS → HS dynamics for more complicated
cases, involving higher density of states and varying electronic character,
as well as the analysis of ultrafast experiments.
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Affiliation(s)
- Mátyás Pápai
- Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary
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28
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Finney BA, Chowdhury SR, Kirkvold C, Vlaisavljevich B. CASPT2 molecular geometries of Fe(II) spin-crossover complexes. Phys Chem Chem Phys 2022; 24:1390-1398. [PMID: 34981806 DOI: 10.1039/d1cp04885f] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Using fully internally contracted (FIC)-CASPT2 analytical gradients, geometry optimizations of spin-crossover complexes are reported. This approach is tested on a series of Fe(II) complexes with different sizes, ranging from 13 to 61 atoms. A combination of active space and basis set choices are employed to investigate their role in determining reliable molecular geometries. The reported strategy demonstrates that a wave function-based level of theory can be used to optimize the geometries of metal complexes in reasonable times and enables one to treat the molecular geometry and electronic structure of the complexes using the same level of theory. For a series of smaller Fe(II) SCO complexes, strong field ligands in the LS state result in geometries with the largest differences between DFT and CASPT2; however, good agreement overall is observed between DFT and CASPT2. For the larger complexes, moderate sized basis sets yield geometries that compare well with DFT and available experimental data. We recommend using the (10e,12o) active space since convergence to a minimum structure was more efficient than with truncated active spaces despite having similar Fe-ligand bond distances.
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Affiliation(s)
- Brian A Finney
- University of South Dakota, Department of Chemistry, 414 E Clark St., Vermillion SD, 57069, USA.
| | - Sabyasachi Roy Chowdhury
- University of South Dakota, Department of Chemistry, 414 E Clark St., Vermillion SD, 57069, USA.
| | - Clara Kirkvold
- University of South Dakota, Department of Chemistry, 414 E Clark St., Vermillion SD, 57069, USA.
| | - Bess Vlaisavljevich
- University of South Dakota, Department of Chemistry, 414 E Clark St., Vermillion SD, 57069, USA.
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29
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Nath R, Manna RN, Paul A. Decoding Regioselective Reaction Mechanism of the Gentisic Acid Catalyzed by Gentisate 1,2-Dioxygenase Enzyme. Catal Sci Technol 2022. [DOI: 10.1039/d2cy00510g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gentisate 1,2-dioxygenase (GDO), a ring-fission non-heme dioxygenase enzyme, displays a unique regioselective reaction of gentisic acid (GTQ) in the presence of molecular oxygen. GTQ is an important intermediate in the...
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30
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Gournay L, Chaban I, Mevellec JY, Humbert B, Janod E, Guerin L, Cammarata M, Daro N, Chastanet G, Collet E. Shifting photo-stationary light-induced excited spin state trapping equilibrium towards higher temperature by increasing light fluence. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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31
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Vidal D, Cirera J, Ribas-Arino J. Accurate calculation of spin-state energy gaps in Fe(III) spin-crossover systems using density functional methods. Dalton Trans 2021; 50:17635-17642. [PMID: 34806100 DOI: 10.1039/d1dt03335b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fe(III) complexes are receiving ever-increasing attention as spin crossover (SCO) systems because they are usually air stable, as opposed to Fe(II) complexes, which are prone to oxidation. Here, we present the first systematic study exclusively devoted to assess the accuracy of several exchange-correlation functionals when it comes to predicting the energy gap between the high-spin (S = 5/2) and the low-spin (S = 1/2) states of Fe(III) complexes. Using a dataset of 24 different Fe(III) hexacoordinated complexes, it is demonstrated that the B3LYP* functional is an excellent choice not only for predicting spin-state energy gaps for Fe(III) complexes undergoing spin-transitions but also for discriminating Fe(III) complexes that are either low- or high-spin in the whole range of temperatures. Our benchmark study has led to the identification of a very versatile Fe(III) compound whose SCO properties can be engineered upon changing a single axial ligand. Overall, this work demonstrates that B3LYP* is a reliable functional for screening new spin-crossover systems with tailored properties.
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Affiliation(s)
- Daniel Vidal
- Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain. .,Departament de Ciència de Materials i Química Física and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
| | - Jordi Cirera
- Departament de Química Inorgànica i Orgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
| | - Jordi Ribas-Arino
- Departament de Ciència de Materials i Química Física and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain.
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32
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Spitsyna NG, Blagov MA, Lazarenko VA, Svetogorov RD, Zubavichus YV, Zorina LV, Maximova O, Yaroslavtsev SA, Rusakov VS, Raganyan GV, Yagubskii EB, Vasiliev AN. Peculiar Spin-Crossover Behavior in the 2D Polymer K[Fe III(5Cl-thsa) 2]. Inorg Chem 2021; 60:17462-17479. [PMID: 34757728 DOI: 10.1021/acs.inorgchem.1c01821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A potassium salt of the N2S2O2-coordination Fe(III) anion K[Fe(5Cl-thsa)2] (1) (5Cl-thsa - 5-chlorosalicylaldehyde thiosemicarbazone) is synthesized and characterized structurally and magnetically over a wide temperature range. Two polymorphs of salt 1 characterized by the common 2D polymer nature and assigned to the same orthorhombic Pbcn space group have been identified. The molecular structure of the minor polymorph of 1 was solved and refined at 100, 250, and 300 K is shown to correspond to the LS configuration. The dominant polymorph of 1 features K+ cations disordered over a few crystallographic sites, while the minor polymorph includes fully ordered K+ cations. The major polymorph exhibits a complete three-step cooperative spin-crossover transition both in the heating and cooling modes: The first step occurs in a temperature range from 2 to 50 K; the second abrupt hysteretic step occurs from 200 to 250 K with T1/2 = 230 K and a 6 K hysteresis loop. The third gradual step occurs from 250 to 440 K. According to 57Fe Mössbauer, XRPD, and EXAFS data, the spin-crossover transition for the dominant polymorph is quite peculiar. Indeed, the increase in the HS concentration by 57% at the second step does not result in the expected significant increase in the iron(III)-ligand bond lengths. In addition, the final step of the spin conversion (ΔγHS = 26%) is associated with a structural phase transition with a symmetry lowering from the orthorhombic (Pbcn) to the monoclinic (P21/n) space group. This nontrivial phenomenon was investigated in detail by applying magnetization measurements, electron spin resonance, 57Fe Mössbauer spectroscopy, and DFT calculations. These results provide a new platform for understanding the multistep spin-crossover character in the Fe(III) thsa-complexes and related compounds.
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Affiliation(s)
- Nataliya G Spitsyna
- Institute of Problems of Chemical Physics, RAS, Chernogolovka, 142432, Russia
| | - Maxim A Blagov
- Institute of Problems of Chemical Physics, RAS, Chernogolovka, 142432, Russia
| | | | | | - Yan V Zubavichus
- Synchrotron Radiation Facility SKIF, Boreskov Institute of Catalysis, SB RAS, Koltsovo 630559, Russia
| | | | - Olga Maximova
- Lomonosov Moscow State University, Moscow 119991, Russia
| | | | | | | | - Eduard B Yagubskii
- Institute of Problems of Chemical Physics, RAS, Chernogolovka, 142432, Russia
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33
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Kwon HY, Ashley DC, Jakubikova E. Halogenation affects driving forces, reorganization energies and "rocking" motions in strained [Fe(tpy) 2] 2+ complexes. Dalton Trans 2021; 50:14566-14575. [PMID: 34586133 DOI: 10.1039/d1dt02314d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Controlling the energetics of spin crossover (SCO) in Fe(II)-polypyridine complexes is critical for designing new multifunctional materials or tuning the excited-state lifetimes of iron-based photosensitizers. It is well established that the Fe-N "breathing" mode is important for intersystem crossing from the singlet to the quintet state, but this does not preclude other, less obvious, structural distortions from affecting SCO. Previous work has shown that halogenation at the 6 and 6'' positions of tpy (tpy = 2,2';6',2''-terpyridine) in [Fe(tpy)2]2+ dramatically increased the lifetime of the excited MLCT state and also had a large impact on the ground state spin-state energetics. To gain insight into the origins of these effects, we used density functional theory calculations to explore how halogenation impacts spin-state energetics and molecular structure in this system. Based on previous work we focused on the ligand "rocking" motion associated with SCO in [Fe(tpy)2]2+ by constructing one-dimensional potential energy surfaces (PESs) along the tpy rocking angle for various spin states. It was found that halogenation has a clear and predictable impact on ligand rocking and spin-state energetics. The rocking is correlated to numerous other geometrical distortions, all of which likely affect the reorganization energies for spin-state changes. We have quantified trends in reorganization energy and also driving force for various spin-state changes and used them to interpret the experimentally measured excited-state lifetimes.
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Affiliation(s)
- Hyuk-Yong Kwon
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, USA.
| | - Daniel C Ashley
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, USA.
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Dr., Raleigh, NC 27695, USA.
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34
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Lerch M, Achazi AJ, Mollenhauer D, Becker J, Schindler S. A Mechanistic Study on the Reaction of Non‐Heme Diiron(III)‐Peroxido Complexes with Benzoyl Chloride. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Markus Lerch
- Institute of Inorganic and Analytical Chemistry Justus-Liebig-Universität Gießen Heinrich-Buff-Ring 17 35392 Gießen Germany
| | - Andreas J. Achazi
- Institute of Physical Chemistry Justus-Liebig-Universität Gießen Heinrich-Buff-Ring 17 35392 Gießen Germany
| | - Doreen Mollenhauer
- Institute of Physical Chemistry Justus-Liebig-Universität Gießen Heinrich-Buff-Ring 17 35392 Gießen Germany
| | - Jonathan Becker
- Institute of Inorganic and Analytical Chemistry Justus-Liebig-Universität Gießen Heinrich-Buff-Ring 17 35392 Gießen Germany
| | - Siegfried Schindler
- Institute of Inorganic and Analytical Chemistry Justus-Liebig-Universität Gießen Heinrich-Buff-Ring 17 35392 Gießen Germany
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35
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Pápai M. Photoinduced Low-Spin → High-Spin Mechanism of an Octahedral Fe(II) Complex Revealed by Synergistic Spin-Vibronic Dynamics. Inorg Chem 2021; 60:13950-13954. [PMID: 34498843 PMCID: PMC8456406 DOI: 10.1021/acs.inorgchem.1c01838] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Fe(II) low-spin (LS; 1A1g, t2g6eg0) → high-spin (HS; 5T2g, t2g4eg2) light-induced excited spin state trapping (LIESST) mechanism solely involving metal-centered states is revealed by synergistic spin-vibronic dynamics simulations. For the octahedral [Fe(NCH)6]2+ complex, we identify an initial ∼100 fs 1T1g → 3T2g intersystem crossing, controlled by vibronic coupling to antisymmetric Fe-N stretching motion. Subsequently, population branching into 3T1g, 5T2g (HS), and 1A1g (LS) is observed on a subpicosecond time scale, with the dynamics dominated by coherent Fe-N breathing wavepackets. These findings are consistent with ultrafast experiments, methodologically establish a new state of the art, and will give a strong impetus for further intriguing dynamical studies on LS → HS photoswitching.
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Affiliation(s)
- Mátyás Pápai
- Wigner Research Centre for Physics, P.O. Box 49, Budapest H-1525, Hungary
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36
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Chakraborty P, Sundararaju B, Manoury E, Poli R. New Borrowing Hydrogen Mechanism for Redox-Active Metals. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02616] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Priyanka Chakraborty
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Basker Sundararaju
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Eric Manoury
- CNRS, LCC (Laboratoire de Chimie de Coordination), Université de Toulouse, UPS, INPT, 205 Route de Narbonne, BP 44099, Toulouse Cedex 4 F-31077, France
| | - Rinaldo Poli
- CNRS, LCC (Laboratoire de Chimie de Coordination), Université de Toulouse, UPS, INPT, 205 Route de Narbonne, BP 44099, Toulouse Cedex 4 F-31077, France
- Institut Universitaire de France, 1, Rue Descartes, Paris Cedex 05 75231, France
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37
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Nandy A, Duan C, Taylor MG, Liu F, Steeves AH, Kulik HJ. Computational Discovery of Transition-metal Complexes: From High-throughput Screening to Machine Learning. Chem Rev 2021; 121:9927-10000. [PMID: 34260198 DOI: 10.1021/acs.chemrev.1c00347] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Transition-metal complexes are attractive targets for the design of catalysts and functional materials. The behavior of the metal-organic bond, while very tunable for achieving target properties, is challenging to predict and necessitates searching a wide and complex space to identify needles in haystacks for target applications. This review will focus on the techniques that make high-throughput search of transition-metal chemical space feasible for the discovery of complexes with desirable properties. The review will cover the development, promise, and limitations of "traditional" computational chemistry (i.e., force field, semiempirical, and density functional theory methods) as it pertains to data generation for inorganic molecular discovery. The review will also discuss the opportunities and limitations in leveraging experimental data sources. We will focus on how advances in statistical modeling, artificial intelligence, multiobjective optimization, and automation accelerate discovery of lead compounds and design rules. The overall objective of this review is to showcase how bringing together advances from diverse areas of computational chemistry and computer science have enabled the rapid uncovering of structure-property relationships in transition-metal chemistry. We aim to highlight how unique considerations in motifs of metal-organic bonding (e.g., variable spin and oxidation state, and bonding strength/nature) set them and their discovery apart from more commonly considered organic molecules. We will also highlight how uncertainty and relative data scarcity in transition-metal chemistry motivate specific developments in machine learning representations, model training, and in computational chemistry. Finally, we will conclude with an outlook of areas of opportunity for the accelerated discovery of transition-metal complexes.
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Affiliation(s)
- Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Michael G Taylor
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Fang Liu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Adam H Steeves
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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38
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Isegawa M, Matsumoto T, Ogo S. H 2 activation by hydrogenase-inspired NiFe catalyst using frustrated Lewis pair: effect of buffer and halide ion in the heterolytic H-H bond cleavage. RSC Adv 2021; 11:28420-28432. [PMID: 35480737 PMCID: PMC9038005 DOI: 10.1039/d1ra05928a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 08/17/2021] [Indexed: 11/21/2022] Open
Abstract
Hydrogen is a clean fuel alternative to fossil fuels, and it is vital to develop catalysts for its efficient activation and production. We investigate the reaction mechanism of H2 activation in an aqueous solution by the recently developed NiFe complex (Ogo et al. Sci. Adv. 2020, 6, eaaz8181) using density functional theory (DFT) calculation. Our computational results showed that H2 is activated using frustrated Lewis pair. That is, H2 binds to the Fe site of the NiFe complex, acting as a Lewis acid, while the added buffer, acting as Lewis base, abstracts protons to form a hydride complex. Furthermore, the higher basicity in the proton abstraction reaction characterises reaction more exergonic and lowers the reaction barrier. In addition, in the proton abstraction by the water molecule, the reaction barrier was lowered when anion such as Cl− is in the vicinity of the water. Understanding the chemical species that contribute to the catalytic process in cooperation with the metal catalyst at the atomic level should help to maximise the function of the catalyst. Hydrogen is a clean fuel alternative to fossil fuels, and it is vital to develop catalysts for its efficient activation and production.![]()
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Affiliation(s)
- Miho Isegawa
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University 744 Moto-oka, Nishi-ku Fukuoka 819-0395 Japan
| | - Takahiro Matsumoto
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University 744 Moto-oka, Nishi-ku Fukuoka 819-0395 Japan
| | - Seiji Ogo
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University 744 Moto-oka, Nishi-ku Fukuoka 819-0395 Japan
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39
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40
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Lykhin AO, Truhlar DG, Gagliardi L. Role of Triplet States in the Photodynamics of Aniline. J Am Chem Soc 2021; 143:5878-5889. [PMID: 33843225 DOI: 10.1021/jacs.1c00989] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of excited heteroaromatic molecules is a key to understanding the photoprotective properties of many biologically relevant chromophores that dissipate their excitation energy nonreactively and thereby prevent the detrimental effects of ultraviolet radiation. Despite their structural variability, most substituted aromatic compounds share a common feature of a repulsive 1πσ* potential energy surface. This surface can lead to photoproducts, and it can also facilitate the population transfer back to the ground electronic state by means of a 1πσ*/S0 conical intersection. Here, we explore a hidden relaxation route involving the triplet electronic state of aniline, which has recently been discovered by means of time-selected photofragment translational spectroscopy [J. Chem. Phys. 2019, 151, 141101]. By using the recently available analytical gradients for multiconfiguration pair-density functional theory, it is now possible to locate the minimum-energy crossing points between states of different spin and therefore compute the intersystem crossing rates with a multireference method, rather than with the less reliable single-reference methods. Using such calculations, we demonstrate that the population loss of aniline in the T1(3ππ*) state is dominated by C6H5NH2 → C6H5NH· + H· dissociation, and we explain the long nonradiative lifetimes of the T1(3ππ*) state at the excitation wavelengths of 294-264 nm.
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Affiliation(s)
- Aleksandr O Lykhin
- Department of Chemistry, Pritzker School of Molecular Engineering, The James Franck Institute and Chicago Center for Theoretical Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Laura Gagliardi
- Department of Chemistry, Pritzker School of Molecular Engineering, The James Franck Institute and Chicago Center for Theoretical Chemistry, The University of Chicago, Chicago, Illinois 60637, United States
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41
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Khurana R, Gupta S, Ali ME. First-Principles Investigations of Magnetic Anisotropy and Spin-Crossover Behavior of Fe(III)-TBP Complexes. J Phys Chem A 2021; 125:2197-2207. [PMID: 33617261 DOI: 10.1021/acs.jpca.1c00022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With the ongoing effort to obtain mononuclear 3d-transition-metal complexes that manifest slow relaxation of magnetization and, hence, can behave as single-molecule magnets (SMMs), we have modeled 14 Fe(III) complexes based on an experimentally synthesized (PMe3)2FeCl3 complex [J. Am. Chem. Soc. 2017, 139 (46), 16474-16477], by varying the axial ligands with group XV elements (N, P, and As) and equatorial halide ligands from F, Cl, Br, and I. Out of these, nine complexes possess large zero field splitting (ZFS) parameter D in the range of -40 to -60 cm-1. The first-principles investigation of the ground-spin state applying density functional theory (DFT) and wave function-based multiconfigurations methods, e.g., SA-CASSCF/NEVPT2, are found to be quite consistent except for few delicate cases with near-degenerate spin states. In such cases, the hybrid B3LYP functional is found to be biased toward high-spin (HS) state. Altering the percentage of exact exchange admixed in the B3LYP functional leads to intermediate-spin (IS) ground state consistent with the multireference calculations. The origin of large zero field splitting (ZFS) in the Fe(III)-based trigonal bipyramidal (TBP) complexes is investigated. Furthermore, a number of complexes are identified with very small ΔGHS-ISadia. values indicating the possible spin-crossover phenomenon between the bistable spin states.
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Affiliation(s)
- Rishu Khurana
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Sameer Gupta
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
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Palomino CM, Sánchez-de-Armas R, Calzado CJ. Theoretical inspection of the spin-crossover [Fe(tzpy) 2(NCS) 2] complex on Au(100) surface. J Chem Phys 2021; 154:034701. [PMID: 33499621 DOI: 10.1063/5.0036612] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We explore the deposition of the spin-crossover [Fe(tzpy)2(NCS)2] complex on the Au(100) surface by means of density functional theory (DFT) based calculations. Two different routes have been employed: low-cost finite cluster-based calculations, where both the Fe complex and the surface are maintained fixed while the molecule approaches the surface; and periodic DFT plane-wave calculations, where the surface is represented by a four-layer slab and both the molecule and surface are relaxed. Our results show that the bridge adsorption site is preferred over the on-top and fourfold hollow ones for both spin states, although they are energetically close. The LS molecule is stabilized by the surface, and the HS-LS energy difference is enhanced by about 15%-25% once deposited. The different Fe ligand field for LS and HS molecules manifests on the composition and energy of the low-lying bands. Our simulated STM images indicate that it is possible to distinguish the spin state of the deposited molecules by tuning the bias voltage of the STM tip. Finally, it should be noted that the use of a reduced size cluster to simulate the Au(100) surface proves to be a low-cost and reliable strategy, providing results in good agreement with those resulting from state-of-the-art periodic calculations for this system.
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Affiliation(s)
- Carlos M Palomino
- Departamento de Química Física, c/Profesor García González, s/n 41012 Sevilla, Spain
| | | | - Carmen J Calzado
- Departamento de Química Física, c/Profesor García González, s/n 41012 Sevilla, Spain
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43
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Dixon IM, Rat S, Sournia-Saquet A, Molnár G, Salmon L, Bousseksou A. On the Spin-State Dependence of Redox Potentials of Spin Crossover Complexes. Inorg Chem 2020; 59:18402-18406. [PMID: 33284611 DOI: 10.1021/acs.inorgchem.0c03043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Resistance switching properties of nanoscale junctions of spin crossover molecules have received recently much interest. In many cases, this property has been traced back to the variation of molecular orbital energies upon spin transition. However, one can also expect a substantial reorganization of the molecular structure due to charge localization, which calls for a better understanding of the relationship between the redox potential and the spin state of the molecule. To investigate this issue, we carried out a detailed density functional theory and variable temperature cyclic voltammetry investigation of the benchmark compound [Fe(HB(1,2,4-triazol-1-yl)3)2] in solution. We show that, for a correct thermodynamical picture, it is necessary to take into account the charge transfer-induced electronic and structural reorganization as well as spin equilibria in the oxidized and reduced species.
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Affiliation(s)
- Isabelle M Dixon
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS/Université Toulouse 3-Paul Sabatier, Université de Toulouse, 118 route de Narbonne, 31062 Toulouse, France
| | - Sylvain Rat
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Alix Sournia-Saquet
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Gábor Molnár
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Lionel Salmon
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
| | - Azzedine Bousseksou
- Laboratoire de Chimie de Coordination, UPR 8241, CNRS and Université de Toulouse, UPS, INP, 205 route de Narbonne, 31077 Toulouse, France
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44
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Spitsyna N, Ovanesyan N, Blagov M, Krapivin V, Lobach A, Dmitriev A, Simonov S, Zorina L, Pilia L, Deplano P, Vasiliev A, Maximova O, Yagubskii E. Multi‐Magnetic Properties of a Novel SCO [Fe(3‐OMe‐Sal
2
trien)][Fe(tdas)
2
]·CH
3
CN Salt. Eur J Inorg Chem 2020. [DOI: 10.1002/ejic.202000873] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Nataliya Spitsyna
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
| | - Nikolay Ovanesyan
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
| | - Maxim Blagov
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
- Lomonosov Moscow State University 119991 Moscow Russia
| | - Vladimir Krapivin
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
| | - Anatolii Lobach
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
| | - Alexei Dmitriev
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
| | - Sergey Simonov
- Institute of Solid State Physics, RAS 142432 Chernogolovka MD Russia
| | - Leokadiya Zorina
- Institute of Solid State Physics, RAS 142432 Chernogolovka MD Russia
| | - Luca Pilia
- Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali Università di Cagliari via Marengo 2, I 09123 Cagliari Italy
| | - Paola Deplano
- Dipartimento di Fisica INSTM Research Unit University of Cagliari Monserrato 09042 Cagliari Italy
| | - Alexander Vasiliev
- Lomonosov Moscow State University 119991 Moscow Russia
- National Research South Ural State University 454080 Chelyabinsk Russia
| | - Olga Maximova
- Lomonosov Moscow State University 119991 Moscow Russia
- National University of Science and Technology "MISIS" 119991 Moscow Russia
| | - Eduard Yagubskii
- Institute of Problems of Chemical Physics, RAS 142432 Chernogolovka MD Russia
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45
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Sárosiné Szemes D, Keszthelyi T, Papp M, Varga L, Vankó G. Quantum-chemistry-aided ligand engineering for potential molecular switches: changing barriers to tune excited state lifetimes. Chem Commun (Camb) 2020; 56:11831-11834. [PMID: 33021253 DOI: 10.1039/d0cc04467a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Substitution of terpyridine at the 4' position with electron withdrawing and donating groups is used to tune the quintet lifetime of its iron(ii) complex. DFT calculations suggest that the energy barrier between the quintet and singlet states can be altered significantly upon substitution, inducing a large variation of the lifetime of the photoexcited quintet state. This prediction was experimentally verified by transient optical absorption spectroscopy and good agreement with the trend expected from the calculations was found. This demonstrates that the potential energy landscape can indeed be rationally tailored by relevant modifications based on DFT predictions. This result should pave the way to advancing efficient theory-based ligand engineering of functional molecules to a wide range of applications.
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46
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Sarmah A, Hobza P. Mechanical force-induced manipulation of electronic conductance in a spin-crossover complex: a simple approach to molecular electronics. NANOSCALE ADVANCES 2020; 2:2907-2913. [PMID: 36132398 PMCID: PMC9417810 DOI: 10.1039/d0na00285b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 05/14/2020] [Indexed: 06/15/2023]
Abstract
The atomic-scale technological sophistication from the last half-decade provides new avenues for the atom-by-atom fabrication of nanostructures with extraordinary precision. This urges the appraisal of the fabrication scheme layout for a modular nanoelectronic device based on an individual molecular complex. The mechanical force-induced distortion to the metal coordination sphere triggers a low-spin (LS) to high-spin (HS) electronic transition in the complex. The controlled structural distortions (relative to a specific bond-angle) are deemed to be the switching parameter for the observed spin-transitions. Mechanical stretching is the key to engineering a spin-state switch in the proposed molecular device. The spin-dependent reversible variation in the electronic conductance concurrent to the unique spin-states can be understood from the state-of-the-art Nonequilibrium Green's Function (NEGF) calculations. Combined with NEGF calculations, the DFT study further provides a qualitative perception of the electronic conductance in the two-terminal device architecture. From the transport calculations, there is also evidence of considerable fluctuation in the spin-dependent electronic conductance at the molecular junction with relative variations in the scattering limit. Subsequently, the present study shows significant advances in the transmission probabilities for the high-spin state of the Fe(ii) complex. The results empower the progress of nanoelectronics at the single molecule level.
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Affiliation(s)
- Amrit Sarmah
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo nam. 2 CZ-16610 Prague 6 Czech Republic +420731015016
- Department of Physical Chemistry, Palacký University CZ-77146 Olomouc Czech Republic
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo nam. 2 CZ-16610 Prague 6 Czech Republic +420731015016
- Department of Physical Chemistry, Palacký University CZ-77146 Olomouc Czech Republic
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47
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Kühne IA, Barker A, Zhang F, Stamenov P, O'Doherty O, Müller-Bunz H, Stein M, Rodriguez BJ, Morgan GG. Modulation of Jahn-Teller distortion and electromechanical response in a Mn 3+spin crossover complex. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:404002. [PMID: 32208375 DOI: 10.1088/1361-648x/ab82d1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/24/2020] [Indexed: 06/10/2023]
Abstract
Structural, magnetic and electromechanical changes resulting from spin crossover between the spin quintet and spin triplet forms of a mononuclear Mn3+complex embedded in six lattices with different charge balancing counterions are reported. Isostructural ClO4-and BF4-salts (1) and (2) each have two unique Mn3+sites which follow different thermal evolution pathways resulting in a crossover from the spin quintet form at room temperature to a 1:1 spin triplet:quintet ratio below 150 K. The PF6-(3) and NO3-(4) salts which each have one unique Mn3+site show a complete conversion from spin quintet to spin triplet over the same temperature range. A complete two step spin crossover is observed in the CF3SO3-lattice (5) with a 1:1 ratio of spin quintet and spin triplet forms at intermediate temperature, while the BPh4-lattice (6) stabilizes the spin triplet form over most of the temperature range with gradual and incomplete spin state switching above 250 K. An electromechanical piezoresponse was detected in NO3-complex4despite crystallization in a centrosymmetric space group. The role of deformations associated with stress-induced spin triplet-spin quintet switching in breaking the local symmetry are discussed and computational analysis is used to estimate the energy gap between the two spin states.
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Affiliation(s)
- Irina A Kühne
- School of Chemistry, University College Dublin (UCD), Dublin, Ireland
| | - Andrew Barker
- School of Chemistry, University College Dublin (UCD), Dublin, Ireland
| | - Fengyuan Zhang
- School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - Plamen Stamenov
- School of Physics, Trinity College Dublin (TCD), Dublin, Ireland
| | - Oisín O'Doherty
- School of Chemistry, University College Dublin (UCD), Dublin, Ireland
| | - Helge Müller-Bunz
- School of Chemistry, University College Dublin (UCD), Dublin, Ireland
| | - Matthias Stein
- Max Planck Institute for Dynamics of Complex Technical Systems, Molecular Simulations and Design Group, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Brian J Rodriguez
- School of Physics and Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - Grace G Morgan
- School of Chemistry, University College Dublin (UCD), Dublin, Ireland
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48
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Moltved KA, Kepp KP. Using electronegativity and hardness to test density functionals. J Chem Phys 2020; 152:244113. [PMID: 32610960 DOI: 10.1063/5.0006189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Density functional theory (DFT) is used in thousands of papers each year, yet lack of universality reduces DFT's predictive capacity, and functionals may produce energy-density imbalances. The absolute electronegativity (χ) and hardness (η) directly reflect the energy-density relationship via the chemical potential ∂E/∂N and we thus hypothesized that they probe universality. We studied χ and η for atoms Z = 1-36 using 50 diverse functionals covering all major classes. Very few functionals describe both χ and η well. η benefits from error cancellation, whereas χ is marred by error propagation from IP and EA; thus, almost all standard GGA and hybrid functionals display a plateau in the MAE at ∼0.2 eV-0.3 eV for η. In contrast, variable performance for χ indicates problems in describing the chemical potential by DFT. The accuracy and precision of a functional is far from linearly related, yet for a universal functional, we expect linearity. Popular functionals such as B3LYP, PBE, and revPBE perform poorly for both properties. Density sensitivity calculations indicate large density-derived errors as occupation of degenerate p- and d-orbitals causes "non-universality" and large dependency on exact exchange. Thus, we argue that performance for χ for the same systems is a hallmark of an important aspect of universality by probing ∂E/∂N. With this metric, B98, B97-1, PW6B95D3, MN-15, rev-TPSS, HSE06, and APFD are the most "universal" among the tested functionals. B98 and B97-1 are accurate for very diverse metal-ligand bonds, supporting that a balanced description of ∂E/∂N and ∂E2/∂N2, via χ and η, is probably a first simple probe of universality.
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Affiliation(s)
- Klaus A Moltved
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
| | - Kasper P Kepp
- Technical University of Denmark, DTU Chemistry, Building 206, 2800 Kgs. Lyngby, Denmark
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49
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Macroscopic Polarization Change via Electron Transfer in a Valence Tautomeric Cobalt Complex. Nat Commun 2020; 11:1992. [PMID: 32332751 PMCID: PMC7181709 DOI: 10.1038/s41467-020-15988-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/02/2020] [Indexed: 12/31/2022] Open
Abstract
Polarization change induced by directional electron transfer attracts considerable attention owing to its fast switching rate and potential light control. Here, we investigate electronic pyroelectricity in the crystal of a mononuclear complex, [Co(phendiox)(rac-cth)](ClO4)·0.5EtOH (1·0.5EtOH, H2phendiox = 9, 10-dihydroxyphenanthrene, rac-cth = racemic 5, 5, 7, 12, 12, 14-hexamethyl-1, 4, 8, 11-tetraazacyclotetradecane), which undergoes a two-step valence tautomerism (VT). Correspondingly, pyroelectric current exhibits double peaks in the same temperature domain with the polarization change consistent with the change in dipole moments during the VT process. Time-resolved Infrared (IR) spectroscopy shows that the photo-induced metastable state can be generated within 150 ps at 190 K. Such state can be trapped for tens of minutes at 7 K, showing that photo-induced polarization change can be realized in this system. These results directly demonstrate that a change in the molecular dipole moments induced by intramolecular electron transfer can introduce a macroscopic polarization change in VT compounds. Polarization change from directional electron transfer attracts considerable attention owing to its fast switching rate and potential light control. Here, the authors provide a proof-of-concept of electronic pyroelectricity induced by intramolecular electron transfer in the single crystal of a valence tautomeric compound.
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50
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Taylor MG, Yang T, Lin S, Nandy A, Janet JP, Duan C, Kulik HJ. Seeing Is Believing: Experimental Spin States from Machine Learning Model Structure Predictions. J Phys Chem A 2020; 124:3286-3299. [PMID: 32223165 PMCID: PMC7311053 DOI: 10.1021/acs.jpca.0c01458] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Determination of ground-state spins
of open-shell transition-metal
complexes is critical to understanding catalytic and materials properties
but also challenging with approximate electronic structure methods.
As an alternative approach, we demonstrate how structure alone can
be used to guide assignment of ground-state spin from experimentally
determined crystal structures of transition-metal complexes. We first
identify the limits of distance-based heuristics from distributions
of metal–ligand bond lengths of over 2000 unique mononuclear
Fe(II)/Fe(III) transition-metal complexes. To overcome these limits,
we employ artificial neural networks (ANNs) to predict spin-state-dependent
metal–ligand bond lengths and classify experimental ground-state
spins based on agreement of experimental structures with the ANN predictions.
Although the ANN is trained on hybrid density functional theory data,
we exploit the method-insensitivity of geometric properties to enable
assignment of ground states for the majority (ca. 80–90%) of
structures. We demonstrate the utility of the ANN by data-mining the
literature for spin-crossover (SCO) complexes, which have experimentally
observed temperature-dependent geometric structure changes, by correctly
assigning almost all (>95%) spin states in the 46 Fe(II) SCO complex
set. This approach represents a promising complement to more conventional
energy-based spin-state assignment from electronic structure theory
at the low cost of a machine learning model.
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Affiliation(s)
- Michael G Taylor
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Tzuhsiung Yang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sean Lin
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jon Paul Janet
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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