1
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Chen YR, Ying TT, Chen YC, Liao PY, Ni ZP, Tong ML. Bidirectional photomagnetism, exciplex fluorescence and dielectric anomalies in a spin crossover Hofmann-type coordination polymer. Chem Sci 2024; 15:9240-9248. [PMID: 38903231 PMCID: PMC11186333 DOI: 10.1039/d4sc00331d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Accepted: 05/09/2024] [Indexed: 06/22/2024] Open
Abstract
Stepped spin crossover (SCO) complexes with three or more spin states have promising applications in high-order data storage, multi-switches and multi-sensors. Further synergy with other functionalities, such as luminescence and dielectric properties, will provide a good chance to develop novel multifunctional SCO materials. Here, a bent pillar ligand and luminescent pyrene guest are integrated into a three-dimensional (3D) Hofmann-type metal-organic framework (MOF) [Fe(dpoda){Au(CN)2}2]·pyrene (dpoda = 2,5-di-(pyridyl)-1,3,4-oxadiazole). The magnetic data show an incomplete and two-step SCO behavior with the sequence of 1 ↔ 1/2 ↔ 1/4. The rare bi-directional light-induced excited spin-state trapping (LIESST) effect and light-induced stepped thermal relaxation after LIESST are observed. The pyrene guests interact with dpoda ligands via offset face-to-face π⋯π interactions to form intermolecular exciplex emissions. The competition between thermal quenching and stepped SCO properties results in a complicated and stepped exciplex fluorescence. Moreover, the stepped dielectric property with higher dielectric permittivity at lower temperature may be related to the more frustrated octahedral distortion parameters in the intermediate spin states. Hence, a 3D Hofmann-type MOF with bent pillar ligands and fluorescent guests illustrates an effective way for the development of multifunctional switching materials.
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Affiliation(s)
- Yan-Ru Chen
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
| | - Ting-Ting Ying
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
| | - Yan-Cong Chen
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
| | - Pei-Yu Liao
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
| | - Zhao-Ping Ni
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
| | - Ming-Liang Tong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, Guangdong Basic Research Center of Excellence for Functional Molecular Engineering, Sun Yat-Sen University Guangzhou 510275 P. R. China
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2
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Martinez-Martinez A, Albacete P, García-Hernández M, Resines-Urien E, Fairen-Jimenez D, Sánchez Costa J. Spin crossover {[Fe(atrz) 3](OTs) 2} n monolith: a green synthesis approach for Robust switchable materials. Dalton Trans 2024; 53:9257-9261. [PMID: 38775103 DOI: 10.1039/d4dt00684d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
This work presents a straightforward, room-temperature synthesis of a robust {[Fe(atrz)3](OTs)2}n monolith. This approach offers a green alternative to traditional nanoparticle synthesis for manipulating spin crossover (SCO) behaviour. The monolith exhibits a more gradual SCO transition at lower temperatures compared to the bulk material, aligning with observations in smaller particle systems. Notably, the synthesis employs a solvent- and surfactant-free approach, simplifying the process and potentially reducing environmental impact, aligning with the principles of green chemistry.
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Affiliation(s)
| | - Pablo Albacete
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
| | - Mar García-Hernández
- Instituto de Ciencia de Materiales de Madrid CSIC, C/Sor Juana Inés de la Cruz, 3, Madrid 28049, Spain
| | | | - David Fairen-Jimenez
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK.
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3
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Zakrzewski J, Liberka M, Wang J, Chorazy S, Ohkoshi SI. Optical Phenomena in Molecule-Based Magnetic Materials. Chem Rev 2024; 124:5930-6050. [PMID: 38687182 PMCID: PMC11082909 DOI: 10.1021/acs.chemrev.3c00840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Since the last century, we have witnessed the development of molecular magnetism which deals with magnetic materials based on molecular species, i.e., organic radicals and metal complexes. Among them, the broadest attention was devoted to molecule-based ferro-/ferrimagnets, spin transition materials, including those exploring electron transfer, molecular nanomagnets, such as single-molecule magnets (SMMs), molecular qubits, and stimuli-responsive magnetic materials. Their physical properties open the application horizons in sensors, data storage, spintronics, and quantum computation. It was found that various optical phenomena, such as thermochromism, photoswitching of magnetic and optical characteristics, luminescence, nonlinear optical and chiroptical effects, as well as optical responsivity to external stimuli, can be implemented into molecule-based magnetic materials. Moreover, the fruitful interactions of these optical effects with magnetism in molecule-based materials can provide new physical cross-effects and multifunctionality, enriching the applications in optical, electronic, and magnetic devices. This Review aims to show the scope of optical phenomena generated in molecule-based magnetic materials, including the recent advances in such areas as high-temperature photomagnetism, optical thermometry utilizing SMMs, optical addressability of molecular qubits, magneto-chiral dichroism, and opto-magneto-electric multifunctionality. These findings are discussed in the context of the types of optical phenomena accessible for various classes of molecule-based magnetic materials.
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Affiliation(s)
- Jakub
J. Zakrzewski
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Michal Liberka
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
- Doctoral
School of Exact and Natural Sciences, Jagiellonian
University, Lojasiewicza
11, 30-348 Krakow, Poland
| | - Junhao Wang
- Department
of Materials Science, Faculty of Pure and Applied Science, University of Tsukuba, 1-1-1 Tonnodai, Tsukuba, Ibaraki 305-8573, Japan
| | - Szymon Chorazy
- Faculty
of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Shin-ichi Ohkoshi
- Department
of Chemistry, School of Science, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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4
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Jornet-Mollá V, Rodríguez-Tarrazó MI, Dolz-Lozano MJ, Giménez-Saiz C, Romero FM. Hydrogen-bonded assemblies of iron(II) spin crossover complexes. Dalton Trans 2024; 53:7848-7856. [PMID: 38625687 DOI: 10.1039/d4dt00579a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
The paper reports on the synthesis, crystal structure, thermal and magnetic properties of spin crossover (SCO) salts containing the [Fe(bpp)2]2+ cation (bpp = 2,6-bis(pyrazol-3-yl)pyridine) and different rigid polycarboxylate anions, such as anthracene-9,10-dicarboxylate (ADC), benzene-1,3,5-tricarboxylate (BTC) and biphenyl-4,4'-dicarboxylate (BPDC). Compound [Fe(bpp)2](ADC)·9H2O (1) shows a porous hydrogen-bonded structure with water molecules sitting in the channels. It contains low-spin (LS) Fe2+ cations that undergo crossover to the high-spin (HS) state upon dehydration. Anhydrous 1 remains HS on cooling at low temperatures. A similar magnetic behaviour is obtained for the partially protonated BTC salt [Fe(bpp)2](HBTC)·5H2O (2), showing a spin change concomitant with dehydration to a HS phase that undergoes gradual and partial SCO on cooling, affecting 25% of the Fe2+ cations. Instead, the BPDC salt [Fe(bpp)2](BPDC)·5H2O (3) has a ground HS state in its fully hydrated form.
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Affiliation(s)
- Verónica Jornet-Mollá
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Marina I Rodríguez-Tarrazó
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Miquel J Dolz-Lozano
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Carlos Giménez-Saiz
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
| | - Francisco M Romero
- Departament de Química Inorgànica, Universitat de València, C/Dr. Moliner, 50, E-46100 Burjassot, Spain.
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5
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Hu XY, Cheng XL, Azam M, Liu FL, Sun D. Guest-Induced Reversible Single-Crystal-to-Single-Crystal Transformation Involving Displacement of 2D Layers and Spin Crossover Behavior Change in a Hofmann-Type Coordination Polymer. Inorg Chem 2024; 63:7746-7753. [PMID: 38609344 DOI: 10.1021/acs.inorgchem.4c00148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2024]
Abstract
A novel two-dimensional (2D) Hofmann-type coordination polymer, {FeII(PyHbim)2[Pd(CN)4]}·2CH3OH [1·2CH3OH, PyHbim = 2-(4-pyridyl)benzimidazole], has been synthesized, which can undergo a spontaneous guest exchange, transforming to 1·2H2O in a single-crystal-to-single-crystal (SCSC) manner, shifting from orthorhombic Cmmm to monoclinic C2/m involving the displacement of 2D layers. The solvent-induced SCSC transformation process was reversible and verified through powder X-ray diffraction (PXRD) and single-crystal X-ray crystallography analyses. Both 1·2CH3OH and 1·2H2O exhibit complete and abrupt spin crossover (SCO) behaviors in two steps, while their SCO temperature ranges drastically shift by ca.100 K, spanning room temperature, owing to different intermolecular interactions resulting from diverse interlayer packing manners and host-guest interactions. Besides, a structural phase transition is observed in 1·2CH3OH, contributing to the two-step spin transition.
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Affiliation(s)
- Xiao-Yang Hu
- School of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, People's Republic of China
| | - Xiang-Long Cheng
- School of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, People's Republic of China
| | - Mohammad Azam
- Department of Chemistry, College of Science, King Saud University, PO BOX 2455, Riyadh 11451, Saudi Arabia
| | - Fu-Ling Liu
- School of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, People's Republic of China
| | - Di Sun
- School of Chemistry and Chemical Engineering, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, People's Republic of China
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6
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Halcrow MA, Vasili HB, Pask CM, Kulak AN, Cespedes O. Activating a high-spin iron(II) complex to thermal spin-crossover with an inert non-isomorphous molecular dopant. Dalton Trans 2024; 53:6983-6992. [PMID: 38563124 DOI: 10.1039/d4dt00443d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
[Fe(bpp)2][ClO4]2 (bpp = 2,6-bis{pyrazol-1-yl}pyridine; monoclinic, C2/c) is high-spin between 5-300 K, and crystallises with a highly distorted molecular geometry that lies along the octahedral-trigonal prismatic distortion pathway. In contrast, [Ni(bpp)2][ClO4]2 (monoclinic, P21) adopts a more regular, near-octahedral coordination geometry. Gas phase DFT minimisations (ω-B97X-D/6-311G**) of [M(bpp)2]2+ complexes show the energy penalty associated with that coordination geometry distortion runs as M2+ = Fe2+ (HS) ≈ Mn2+ (HS) < Zn2+ ≈ Co2+ (HS) ≲ Cu2+ ≪ Ni2+ ≪ Ru2+ (LS; HS = high-spin, LS = low-spin). Slowly crystallised solid solutions [FexNi1-x(bpp)2][ClO4]2 with x = 0.53 (1a) and 0.74 (2a) adopt the P21 lattice, while x = 0.87 (3a) and 0.94 (4a) are mixed-phase materials with the high-spin C2/c phase as the major component. These materials exhibit thermal spin-transitions at T½ = 250 ± 1 K which occurs gradually in 1a, and abruptly and with narrow thermal hysteresis in 2a-4a. The transition proceeds to 100% completeness in 1a and 2a; that is, the 26% Ni doping in 2a is enough to convert high-spin [Fe(bpp)2][ClO4]2 into a cooperative, fully SCO-active material. These results were confirmed crystallographically for 1a and 2a, which revealed similarities and differences between these materials and the previously published [FexNi1-x(bpp)2][BF4]2 series. Rapidly precipitated powders with the same compositions (1b-4b) mostly resemble 1a-4a, except that 2b is a mixed-phase material; 2b-4b also contain a fraction of amorphous solid in addition to the two crystal phases. The largest iron fraction that can be accommodated by the P21 phase in this system is 0.7 ± 0.1.
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Affiliation(s)
- Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
| | - Hari Babu Vasili
- School of Physics and Astronomy, University of Leeds, W. H. Bragg Building, Leeds, LS2 9JT, UK
| | - Christopher M Pask
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
| | - Alexander N Kulak
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
| | - Oscar Cespedes
- School of Physics and Astronomy, University of Leeds, W. H. Bragg Building, Leeds, LS2 9JT, UK
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7
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Capel Berdiell I, Michaels E, Munro OQ, Halcrow MA. A Survey of the Angular Distortion Landscape in the Coordination Geometries of High-Spin Iron(II) 2,6-Bis(pyrazolyl)pyridine Complexes. Inorg Chem 2024; 63:2732-2744. [PMID: 38258555 PMCID: PMC10848207 DOI: 10.1021/acs.inorgchem.3c04138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/04/2024] [Accepted: 01/11/2024] [Indexed: 01/24/2024]
Abstract
Reaction of 2,4,6-trifluoropyridine with sodium 3,4-dimethoxybenzenethiolate and 2 equiv of sodium pyrazolate in tetrahydrofuran at room temperature affords 4-(3,4-dimethoxyphenylsulfanyl)-2,6-di(pyrazol-1-yl)pyridine (L), in 30% yield. The iron(II) complexes [FeL2][BF4]2 (1a) and [FeL2][ClO4]2 (1b) are high-spin with a highly distorted six-coordinate geometry. This structural deviation from ideal D2d symmetry is common in high-spin [Fe(bpp)2]2+ (bpp = di{pyrazol-1-yl}pyridine) derivatives, which are important in spin-crossover materials research. The magnitude of the distortion in 1a and 1b is the largest yet discovered for a mononuclear complex. Gas-phase DFT calculations at the ω-B97X-D/6-311G** level of theory identified four minimum or local minimum structural pathways across the distortion landscape, all of which are observed experimentally in different complexes. Small distortions from D2d symmetry are energetically favorable in complexes with electron-donating ligand substituents, including sulfanyl groups, which also have smaller energy penalties associated with the lowest energy distortion pathway. Natural population analysis showed that these differences reflect greater changes to the Fe-N{pyridyl} σ-bonding as the distortion proceeds, in the presence of more electron-rich pyridyl donors. The results imply that [Fe(bpp)2]2+ derivatives with electron-donating pyridyl substituents are more likely to undergo cooperative spin transitions in the solid state. The high-spin salt [Fe(bpp)2][CF3SO3]2, which also has a strong angular distortion, is also briefly described and included in the analysis.
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Affiliation(s)
| | - Evridiki Michaels
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Orde Q. Munro
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
| | - Malcolm A. Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, U.K.
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8
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Zeng FL, Jin XT, Zhao J, Zhang SX, Xue C, Luo YH. Construction and screening of spin-crossover-sponge materials based on iron(II)-triazole coordination polymers. Dalton Trans 2024; 53:2333-2340. [PMID: 38205731 DOI: 10.1039/d3dt03531j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
Iron(II)-triazole coordination polymers have attracted considerable interest for their synthetic versatility, which allows tuning their spin-crossover (SCO) properties. Embedding SCO solid particles in sponge matrices is a simple, powerful, and generic approach to construct processable SCO materials. Here, we have studied a series of magnetic frameworks based on partial ligand substitution by using different chemical mixtures of two organic ligands, yielding four isostructural coordination polymers. The integration of the hygroscopic SCO material has endowed the composite sponge with the ability to capture moisture under ambient conditions. In particular, not only does a spin-crossover transition during absorption occur, but also a color variation has been achieved by varying humidity. The consequences of cooperativity and the exposed surface of the composite sponge on the spin transition were evaluated and the most promising materials among them were screened. This work provides guiding significance for the fabrication and practical application of spin-crossover-sponge materials.
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Affiliation(s)
- Feng-Lian Zeng
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
| | - Xue-Ting Jin
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
| | - Jie Zhao
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
| | - Shu-Xin Zhang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
| | - Cheng Xue
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
| | - Yang-Hui Luo
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P.R. China.
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9
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Yang G, Wu SG, Ruan ZY, Chen YC, Xie KP, Ni ZP, Tong ML. Single-Crystal Transformation Engineering the Spin Change of Metal-Organic Frameworks via Cluster Deconstruction. Angew Chem Int Ed Engl 2023; 62:e202312685. [PMID: 37779343 DOI: 10.1002/anie.202312685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/29/2023] [Accepted: 09/29/2023] [Indexed: 10/03/2023]
Abstract
Spin crossover (SCO) materials with new architectures will expand and enrich the research in the SCO field. Here, we report two metal-organic frameworks (MOFs) containing tetradentate organic ligands and hexatopic linkers [Ag8 X8 (CN)6 ]6- (X=Br and I), which represents the first SCO MOF with clusters as building blocks. The silver halide cluster can be further removed after reacting with lithium tetracyanoquinodimethan (LiTCNQ). Such post-synthetic modification (PSM) is realized via single-crystal to single-crystal (SCSC) transformation from urk to nbo topology. Accordingly, the spin state and fluorescence properties are greatly modified by cluster deconstruction. Therefore, these achievements will provide new ideas for the design of new SCO systems and the development of PSM methods.
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Affiliation(s)
- Guang Yang
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Si-Guo Wu
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Ze-Yu Ruan
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Yan-Cong Chen
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Kai-Ping Xie
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Zhao-Ping Ni
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Ming-Liang Tong
- Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, IGCME, GBRCE for Functional Molecular Engineering, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
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10
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Kulmaczewski R, Halcrow MA. Iron(II) complexes of 2,6-bis(imidazo[1,2- a]pyridin-2-yl)pyridine and related ligands with annelated distal heterocyclic donors. Dalton Trans 2023; 52:14928-14940. [PMID: 37799008 DOI: 10.1039/d3dt02747c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Following a published synthesis of 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine (L1), treatment of α,α'-dibromo-2,6-diacetylpyridine with 2 equiv. 2-aminopyrimidine or 2-aminoquinoline in refluxing acetonitrile respectively gives 2,6-bis(imidazo[1,2-a]pyrimidin-2-yl)pyridine (L2) and 2,6-bis(imidazo[1,2-a]quinolin-2-yl)pyridine (L3). Solvated crystals of [Fe(L1)2][BF4]2 (1[BF4]2) and [Fe(L2)2][BF4]2 (2[BF4]2) are mostly high-spin, although one solvate of 1[BF4]2 undergoes thermal spin-crossover on cooling. The iron coordination geometry is consistently distorted in crystals of 2[BF4]2 which may reflect the influence of intramolecular, inter-ligand N⋯π interactions on the molecular conformation. Only 1 : 1 Fe : L3 complexes were observed in solution, or isolated in the solid state; a crystal structure of [FeBr(py)2L3]Br·0.5H2O (py = pyridine) is presented. A solvate crystal structure of high-spin [Fe(L4)2][BF4]2 (L4 = 2,6-di{quinolin-2-yl}pyridine; 4[BF4]2) is also described, which exhibits a highly distorted six-coordinate geometry with a helical ligand conformation. The iron(II) complexes are high-spin in solution at room temperature, but 1[BF4]2 and 2[BF4]2 undergo thermal spin-crossover equilibria on cooling. All the compounds exhibit a ligand-based emission in solution at room temperature. Gas phase DFT calculations mostly reproduce the spin state properties of the complexes, but show small anomalies attributed to intramolecular, inter-ligand dispersion interactions in the sterically crowded molecules.
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Affiliation(s)
- Rafal Kulmaczewski
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
| | - Malcolm A Halcrow
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK LS2 9JT.
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11
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Hu Y, Picher M, Palluel M, Daro N, Freysz E, Stoleriu L, Enachescu C, Chastanet G, Banhart F. Laser-Driven Transient Phase Oscillations in Individual Spin Crossover Particles. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2303701. [PMID: 37246252 DOI: 10.1002/smll.202303701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Indexed: 05/30/2023]
Abstract
An unusual expansion dynamics of individual spin crossover nanoparticles is studied by ultrafast transmission electron microscopy. After exposure to nanosecond laser pulses, the particles exhibit considerable length oscillations during and after their expansion. The vibration period of 50-100 ns is of the same order of magnitude as the time that the particles need for a transition from the low-spin to the high-spin state. The observations are explained in Monte Carlo calculations using a model where elastic and thermal coupling between the molecules within a crystalline spin crossover particle govern the phase transition between the two spin states. The experimentally observed length oscillations are in agreement with the calculations, and it is shown that the system undergoes repeated transitions between the two spin states until relaxation in the high-spin state occurs due to energy dissipation. Spin crossover particles are therefore a unique system where a resonant transition between two phases occurs in a phase transformation of first order.
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Affiliation(s)
- Yaowei Hu
- Institut de Physique et Chimie des Matériaux UMR 7504, Université de Strasbourg & CNRS, Strasbourg, 67034, France
| | - Matthieu Picher
- Institut de Physique et Chimie des Matériaux UMR 7504, Université de Strasbourg & CNRS, Strasbourg, 67034, France
| | - Marlène Palluel
- Université de Bordeaux, CNRS, Bordeaux INP (ICMCB-UMR 5026), Pessac, 33600, France
| | - Nathalie Daro
- Université de Bordeaux, CNRS, Bordeaux INP (ICMCB-UMR 5026), Pessac, 33600, France
| | - Eric Freysz
- Université de Bordeaux, CNRS UMR 5798, LOMA, Talence cedex, 33405, France
| | - Laurentiu Stoleriu
- Faculty of Physics, Alexandru Ioan Cuza University, Iasi, 700506, Romania
| | - Cristian Enachescu
- Faculty of Physics, Alexandru Ioan Cuza University, Iasi, 700506, Romania
| | - Guillaume Chastanet
- Université de Bordeaux, CNRS, Bordeaux INP (ICMCB-UMR 5026), Pessac, 33600, France
| | - Florian Banhart
- Institut de Physique et Chimie des Matériaux UMR 7504, Université de Strasbourg & CNRS, Strasbourg, 67034, France
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García-López V, El Jastimi HEM, Juráková J, Clemente-León M, Coronado E. Iron(II) Complexes of 2,6-Di[4-(ethylcarboxy)pyrazol-1-yl]pyridine with Reversible Guest-Modulated Spin-Crossover Behavior. CRYSTAL GROWTH & DESIGN 2023; 23:2730-2738. [PMID: 37038402 PMCID: PMC10080648 DOI: 10.1021/acs.cgd.2c01524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/21/2023] [Indexed: 06/19/2023]
Abstract
Three solvatomorphs of the iron(II) complex of 2,6-di[4-(ethylcarboxy)pyrazol-1-yl]pyridine (bpCOOEt2p) of formulas [Fe(bpCOOEt2p)2](ClO4)2·1.5MeNO2 (1), [Fe(bpCOOEt2p)2](ClO4)2·MeNO2 (2), and [Fe(bpCOOEt2p)2](ClO4)2·2MeNO2 (3) have been prepared and characterized. They show interesting spin-crossover (SCO) properties ranging from partial to complete thermal spin transitions and a light-induced excited spin-state trapping (LIESST) effect. In solvatomorph 2, a robust structure is formed with channels that enable the entrance or removal of solvent molecules by vapor diffusion without losing the crystallinity. Thus, solvent-exchanged samples [Fe(bpCOOEt2p)2](ClO4)2·MeNO2 (2·MeNO 2 ), [Fe(bpCOOEt2p)2](ClO4)2·MeCN (2·MeCN), [Fe(bpCOOEt2p)2](ClO4)2·0.5Me2CO (2·Me 2 CO), and [Fe(bpCOOEt2p)2](ClO4)2·MeCOOH (2·MeCOOH) were prepared by vapor diffusion of the solvents in a crystal of the compound previously heated to 400 K in a single-crystal to single-crystal (SCSC) fashion. Interestingly, this causes a change of spin state with a stabilization of the low-spin state in 2·Me 2 CO and the high-spin state in 2·MeCN. Therefore, the SCO properties of 2 can be tuned in a reversible way by exposure to different solvents.
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Affiliation(s)
- Víctor García-López
- Instituto
de Ciencia Molecular (ICMol), Universidad
de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Hanane El Mansour El Jastimi
- Instituto
de Ciencia Molecular (ICMol), Universidad
de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Jana Juráková
- Instituto
de Ciencia Molecular (ICMol), Universidad
de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
- Central
European Institute of Technology, Brno University
of Technology, Purkyn̆ova
123, 61200 Brno, Czech Republic
| | - Miguel Clemente-León
- Instituto
de Ciencia Molecular (ICMol), Universidad
de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
| | - Eugenio Coronado
- Instituto
de Ciencia Molecular (ICMol), Universidad
de Valencia, Catedrático José Beltrán 2, 46980 Paterna, Spain
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