51
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Irons TJP, Spence L, David G, Speake BT, Helgaker T, Teale AM. Analyzing Magnetically Induced Currents in Molecular Systems Using Current-Density-Functional Theory. J Phys Chem A 2020; 124:1321-1333. [DOI: 10.1021/acs.jpca.9b10833] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tom J. P. Irons
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, U.K
| | - Lucy Spence
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, U.K
| | - Grégoire David
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, U.K
| | | | - Trygve Helgaker
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, N-0315 Oslo, Norway
- Centre for Advanced Study (CAS) at the Norwegian Academy of Science and Letters, Drammensveien 78, N-0271 Oslo, Norway
| | - Andrew M. Teale
- School of Chemistry, University of Nottingham, NG7 2RD Nottingham, U.K
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, N-0315 Oslo, Norway
- Centre for Advanced Study (CAS) at the Norwegian Academy of Science and Letters, Drammensveien 78, N-0271 Oslo, Norway
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52
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Abstract
We have proven that Baird's rule can also be applied to a series of all-metal species with both σ- and π-aromaticity.
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Affiliation(s)
- Dandan Chen
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM)
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
| | - Dariusz W. Szczepanik
- Institute of Computational Chemistry and Catalysis and Department of Chemistry
- University of Girona
- Girona
- Spain
- K. Guminski Department of Theoretical Chemistry
| | - Jun Zhu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM)
- Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and Department of Chemistry
- College of Chemistry and Chemical Engineering
- Xiamen University
- Xiamen
| | - Miquel Solà
- Institute of Computational Chemistry and Catalysis and Department of Chemistry
- University of Girona
- Girona
- Spain
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53
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Zhou Z, Kawade RK, Wei Z, Kuriakose F, Üngör Ö, Jo M, Shatruk M, Gershoni‐Poranne R, Petrukhina MA, Alabugin IV. Negative Charge as a Lens for Concentrating Antiaromaticity: Using a Pentagonal “Defect” and Helicene Strain for Cyclizations. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201911319] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Zheng Zhou
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Rahul Kisan Kawade
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Zheng Wei
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Febin Kuriakose
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Ökten Üngör
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Minyoung Jo
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Michael Shatruk
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | | | - Marina A. Petrukhina
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Igor V. Alabugin
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
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54
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Zhou Z, Kawade RK, Wei Z, Kuriakose F, Üngör Ö, Jo M, Shatruk M, Gershoni‐Poranne R, Petrukhina MA, Alabugin IV. Negative Charge as a Lens for Concentrating Antiaromaticity: Using a Pentagonal “Defect” and Helicene Strain for Cyclizations. Angew Chem Int Ed Engl 2019; 59:1256-1262. [DOI: 10.1002/anie.201911319] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Indexed: 01/05/2023]
Affiliation(s)
- Zheng Zhou
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Rahul Kisan Kawade
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Zheng Wei
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Febin Kuriakose
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Ökten Üngör
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Minyoung Jo
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | - Michael Shatruk
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
| | | | - Marina A. Petrukhina
- Department of Chemistry University at Albany State University of New York Albany NY 12222 USA
| | - Igor V. Alabugin
- Department of Chemistry and Biochemistry Florida State University Tallahassee FL 32306-4390 USA
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55
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Kim J, Oh J, Park S, Zafra JL, DeFrancisco JR, Casanova D, Lim M, Tovar JD, Casado J, Kim D. Two-electron transfer stabilized by excited-state aromatization. Nat Commun 2019; 10:4983. [PMID: 31676760 PMCID: PMC6825201 DOI: 10.1038/s41467-019-12986-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 10/10/2019] [Indexed: 12/28/2022] Open
Abstract
The scientific significance of excited-state aromaticity concerns with the elucidation of processes and properties in the excited states. Here, we focus on TMTQ, an oligomer composed of a central 1,6-methano[10]annulene and 5-dicyanomethyl-thiophene peripheries (acceptor-donor-acceptor system), and investigate a two-electron transfer process dominantly stabilized by an aromatization in the low-energy lying excited state. Our spectroscopic measurements quantitatively observe the shift of two π-electrons between donor and acceptors. It is revealed that this two-electron transfer process accompanies the excited-state aromatization, producing a Baird aromatic 8π core annulene in TMTQ. Biradical character on each terminal dicyanomethylene group of TMTQ allows a pseudo triplet-like configuration on the 8π core annulene with multiexcitonic nature, which stabilizes the energetically unfavorable two-charge separated state by the formation of Baird aromatic core annulene. This finding provides a comprehensive understanding of the role of excited-state aromaticity and insight to designing functional photoactive materials. Excited state aromaticity gives rise to unique photophysical properties which may aid the design of functional photoactive materials. Here, the authors spectroscopically characterize an acceptor-donor-acceptor system featuring a two-electron transfer process stabilized by aromatization in the lower energy excited state.
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Affiliation(s)
- Jinseok Kim
- Spectroscopy Laboratory for Functional π-electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea
| | - Juwon Oh
- Spectroscopy Laboratory for Functional π-electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea
| | - Seongchul Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, 46241, Korea
| | - Jose L Zafra
- Department of Physical Chemistry, University of Málaga, Andalucia-Tech, Campus de Teatinos s/n, 29071, Málaga, Spain
| | - Justin R DeFrancisco
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA
| | - David Casanova
- Donostia, International Physics Center (DIPC) & IKERBASQUE - Basque Foundation for Science, Paseo Manuel de Lardizabal, 4, 20018, Donostia-San Sebastián, Euskadi, Spain.
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan, 46241, Korea.
| | - John D Tovar
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD, 21218, USA.
| | - Juan Casado
- Department of Physical Chemistry, University of Málaga, Andalucia-Tech, Campus de Teatinos s/n, 29071, Málaga, Spain.
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea.
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56
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Baranac-Stojanović M. Triplet-State Structures, Energies, and Antiaromaticity of BN Analogues of Benzene and Their Benzo-Fused Derivatives. J Org Chem 2019; 84:13582-13594. [PMID: 31538474 DOI: 10.1021/acs.joc.9b01858] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is well known that benzene is aromatic in the ground state (the Hückel's rule) and antiaromatic in the first triplet (T1) excited state (the Baird's rule). Whereas its BN analogues, the three isomeric dihydro-azaborines, have been shown to have various degrees of aromaticity in their ground state, almost no data are available for their T1 states. Thus, the purpose of this work is to theoretically [B3LYP/6-311+G(d,p)] predict structures, energies, and antiaromaticity of T1 dihydro-azaborines and some benzo-fused derivatives. Conclusions are based on spin density analysis, isogyric and hydrogenation reactions, HOMA, NICS, and ACID calculations. The results suggest that singlet-triplet energy gaps, antiaromaticity, and related excited-state properties of benzene, naphthalene, and anthracene could be tuned and controlled by the BN substitution pattern. While all studied compounds remain (nearly) planar upon excitation, the spin density distribution in T1 1,4-dihydro-azaborine induces a conformational change by which the two co-planar C-H bonds in the ground state become perpendicular to each other in the excited state. This predicted change in geometry could be of interest for the design of new photomechanical materials. Excitation of B-CN/N-NH2 1,4-azaborine would have a few effects: intramolecular charge transfer, aromaticity reversal, rotation, and stereoelectronic Umpolung of the amino group.
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Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry , University of Belgrade , Studentski trg 12-16 , P.O.Box 158, 11000 Belgrade , Serbia
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57
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Malcomson T, Azizi A, Momen R, Xu T, Kirk SR, Paterson MJ, Jenkins S. Stress Tensor Eigenvector Following with Next-Generation Quantum Theory of Atoms in Molecules: Excited State Photochemical Reaction Path from Benzene to Benzvalene. J Phys Chem A 2019; 123:8254-8264. [PMID: 31487180 DOI: 10.1021/acs.jpca.9b07519] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this investigation, we considered both the scalar and 3-D vector-based measures of bonding using next generation quantum theory of atoms in molecules (QTAIM), constructed from the preferred direction of electronic charge density accumulation, to better understand the photochemical reaction associated with of the formation of benzvalene from benzene. The formation of benzvalene from benzene resulted in two additional C-C bonds forming compared with the benzene. The creation of the additional C-C bonds was explained in terms of an increasing the favorability of the reaction process by maximizing the bonding density. The topological instability of the benzvalene structure was determined using the scalar and vector-based measures to explain the short chemical half-life of benzvalene in terms of the competition between the formation of unstable new C-C bonding that also destabilizes nearest neighbor C-C bonds. The explosive character of benzvalene is indicated by the unusual tendency of the C-C bonds to rupture as easily as weak bonding. The topological instability of the short strong C-C bonds was explained by the existence of measures from conventional and next generation QTAIM that previously have only been observed in weak interactions; such measures included twisted 3-D bonding descriptors.
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Affiliation(s)
- Thomas Malcomson
- Institute of Chemical Sciences, School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh , EH14 4AS , U.K
| | - Alireza Azizi
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research and Key Laboratory of Resource National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha , Hunan 410081 , China
| | - Roya Momen
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research and Key Laboratory of Resource National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha , Hunan 410081 , China
| | - Tianlv Xu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research and Key Laboratory of Resource National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha , Hunan 410081 , China
| | - Steven R Kirk
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research and Key Laboratory of Resource National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha , Hunan 410081 , China
| | - Martin J Paterson
- Institute of Chemical Sciences, School of Engineering and Physical Sciences , Heriot-Watt University , Edinburgh , EH14 4AS , U.K
| | - Samantha Jenkins
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research and Key Laboratory of Resource National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering , Hunan Normal University , Changsha , Hunan 410081 , China
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58
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Abstract
Baird's rule explains why and when excited-state proton transfer (ESPT) reactions happen in organic compounds. Bifunctional compounds that are [4n + 2] π-aromatic in the ground state, become [4n + 2] π-antiaromatic in the first 1ππ* states, and proton transfer (either inter- or intramolecularly) helps relieve excited-state antiaromaticity. Computed nucleus-independent chemical shifts (NICS) for several ESPT examples (including excited-state intramolecular proton transfers (ESIPT), biprotonic transfers, dynamic catalyzed transfers, and proton relay transfers) document the important role of excited-state antiaromaticity. o-Salicylic acid undergoes ESPT only in the "antiaromatic" S1 (1ππ*) state, but not in the "aromatic" S2 (1ππ*) state. Stokes' shifts of structurally related compounds [e.g., derivatives of 2-(2-hydroxyphenyl)benzoxazole and hydrogen-bonded complexes of 2-aminopyridine with protic substrates] vary depending on the antiaromaticity of the photoinduced tautomers. Remarkably, Baird's rule predicts the effect of light on hydrogen bond strengths; hydrogen bonds that enhance (and reduce) excited-state antiaromaticity in compounds become weakened (and strengthened) upon photoexcitation.
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59
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Baranac-Stojanović M. A DFT Study of the Modulation of the Antiaromatic and Open-Shell Character of Dibenzo[a,f]pentalene by Employing Three Strategies: Additional Benzoannulation, BN/CC Isosterism, and Substitution. Chemistry 2019; 25:9747-9757. [PMID: 31107568 DOI: 10.1002/chem.201901845] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/17/2019] [Indexed: 11/07/2022]
Abstract
Dibenzo[a,f]pentalene ([a,f]DBP) is a highly antiaromatic molecule having appreciable open-shell singlet character in its ground state. In this work, DFT calculations at the B3LYP/6-311+G(d,p) level of theory were performed to explore the efficiency of three strategies, that is, BN/CC isosterism, substitution, and (di)benzoannulation of [a,f]DBP, in controlling its electronic state and (anti)aromaticity. To evaluate the type and extent of the latter, the harmonic oscillator model of aromaticity (HOMA) and aromatic fluctuation (FLU) indices were used, along with the nucleus-independent chemical shift NICS-XY-scan procedure. The results suggest that all three strategies could be employed to produce either the closed-shell system or open-shell species, which may be in the singlet or triplet ground state. Triplet states have been characterized as aromatic, which is in accordance with Baird's rule. All the singlet states were found to have weaker global paratropicity than [a,f]DBP. Additional (di)benzo fusion adds local aromatic subunit(s) and mainly retains the topology of the paratropic ring currents of the basic molecule. The substitution of two carbon atoms by the isoelectronic BN pair, or the introduction of substituents, results either in the same type and very similar topology of ring currents as in the parent compound, or leads to (anti)aromatic and nonaromatic subunits. The triplet states of all the examined compounds are also discussed.
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60
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Ma J, Šekutor M, Škalamera Đ, Basarić N, Phillips DL. Formation of Quinone Methides by Ultrafast Photodeamination: A Spectroscopic and Computational Study. J Org Chem 2019; 84:8630-8637. [PMID: 31244153 DOI: 10.1021/acs.joc.9b01085] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Formation of quinone methides (QMs) by photoelimination of an ammonium salt from cresol derivatives was investigated by femtosecond transient absorption spectroscopy (fs-TA) and computationally by time-dependent density functional theory using the PCM(water)/(TD-)B3LYP/6-311++G(d,p) level of theory. The photoelimination takes place in an adiabatic ultrafast reaction on the S1 potential energy surface delivering the corresponding QMs(S1), which were detected by fs-TA. Computations predicted a high-energy cation intermediate in the pathway between the Franck-Condon state of a monoammonium salt and the corresponding QM(S1) that was not detected by fs-TA. On the other hand, elimination from a disalt in H2O takes place in one step, giving directly the QM(S1). The combined experimental and theoretical investigation fully disclosed the formation of QMs by the deamination reaction mechanism, which is important in the application of cresols or similar molecules in biological systems.
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Affiliation(s)
- Jiani Ma
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science , Northwest University , Xi'an 710065 , P. R. China
| | - Marina Šekutor
- Department of Organic Chemistry and Biochemistry , Ruđer Bošković Institute , Bijenička cesta 54 , 10 000 Zagreb , Croatia
| | - Đani Škalamera
- Department of Organic Chemistry and Biochemistry , Ruđer Bošković Institute , Bijenička cesta 54 , 10 000 Zagreb , Croatia
| | - Nikola Basarić
- Department of Organic Chemistry and Biochemistry , Ruđer Bošković Institute , Bijenička cesta 54 , 10 000 Zagreb , Croatia
| | - David Lee Phillips
- Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , Hong Kong S.A.R. , P. R. China
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61
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León I, Fernández JA. Influence of the solvent in the electronic excitation of aromatic alcohols: Excited state IR-UV of propofol(H 2O) 8. J Chem Phys 2019; 150:214306. [PMID: 31176335 DOI: 10.1063/1.5093813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It is well known that water plays an important role in the reactivity and dynamics in a solution of molecules in electronic excited states. For example, electronic excitation is usually accompanied by a solvent rearrangement that may also influence the redistribution of the excitation energy. However, there is a lack of experimental data on such processes. Here, we explore the structural changes that follow electronic excitation in aggregates of propofol (2,6-diisopropylphenol) with up to eight water molecules, using a combination of mass-resolved excitation spectroscopy and density functional theory calculations. The molecules of water form a polyhedron around the hydroxyl group of propofol, also interacting with the π cloud of the aromatic ring. Electronic excitation produces a strong structural change in the water superstructure, which moves to an interaction with one of the carbon atoms of the aromatic ring, producing its distortion into a prefulvenic structure. Such deformation is not observed in smaller water clusters or in propofol-phenol aggregates highlighting the decisive role played by the solvent.
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Affiliation(s)
- Iker León
- Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV-EHU), Barrio Sarriena S/N, Leioa 48940, Spain
| | - José A Fernández
- Department of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV-EHU), Barrio Sarriena S/N, Leioa 48940, Spain
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62
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Skov AB, Ree N, Gertsen AS, Chabera P, Uhlig J, Lissau JS, Nucci L, Pullerits T, Mikkelsen KV, Brøndsted Nielsen M, Sølling TI, Hansen T. Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity. CHEMPHOTOCHEM 2019. [DOI: 10.1002/cptc.201900088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Anders B. Skov
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
| | - Nicolai Ree
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
| | - Anders S. Gertsen
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
- DTU EnergyTechnical University of Denmark Frederiksborgvej 399 4000 Roskilde Denmark
| | - Pavel Chabera
- Division of Chemical PhysicsLund Universitet Naturvetarvägen 16 22362 Lund Sweden
| | - Jens Uhlig
- Division of Chemical PhysicsLund Universitet Naturvetarvägen 16 22362 Lund Sweden
| | - Jonas S. Lissau
- SDU NanoSYD, Mads Clausen InstituteUniversity of Southern Denmark, Alsion 2 6400 Sønderborg Denmark
| | - Luigi Nucci
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
- Dipartimento di Chimica e Chimica IndustrialeUniversitá di Pisa Via Moruzzi 3 Pisa Italy
| | - Tõnu Pullerits
- Division of Chemical PhysicsLund Universitet Naturvetarvägen 16 22362 Lund Sweden
| | - Kurt V. Mikkelsen
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
| | - Mogens Brøndsted Nielsen
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
| | - Theis I. Sølling
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
- King Fahd University of Petroleum and Minerals Bldg. 15, Rm. 6124 Dhahran 31261 Kingdom of Saudi Arabia
| | - Thorsten Hansen
- Department of ChemistryUniversity of Copenhagen Universitetsparken 5 DK-2100 Copenhagen Ø Denmark
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63
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Toldo J, El Bakouri O, Solà M, Norrby PO, Ottosson H. Is Excited-State Aromaticity a Driving Force for Planarization of Dibenzannelated 8π-Electron Heterocycles? Chempluschem 2019; 84:712-721. [PMID: 31944021 DOI: 10.1002/cplu.201900066] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/28/2019] [Indexed: 11/11/2022]
Abstract
Compounds with dibenzannelated heterocycles with eight π-electrons are found in a range of applications. These molecules often adopt a bent structure in the ground state (S0 ) but can become planar in the first excited states (S1 and T1 ) because of the cyclically conjugated 4nπ central ring, which fulfils the requirements for excited state aromaticity. We report on a quantum chemical investigation of the aromatic character in the S1 and T1 states of dibenzannelated seven- and six-membered heterocycles with one, two, or three heteroatoms in the 8π-electron ring. These states could have ππ* or nπ* character. We find that compounds with one or two heteroatoms in the central ring have ππ* states as their S1 and T1 states. They are to a significant degree influenced by excited state aromaticity, and their optimal structures are planar or nearly planar. Among the heteroatoms, nitrogen provides for the strongest excited state aromaticity whereas oxygen provides for the weakest, following the established trend of the S0 state. Yet, dibenzannelated seven-membered-ring compounds with N=N bonds have non-aromatic nπ* states with strongly puckered structures as their S1 and T1 states.
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Affiliation(s)
- Josene Toldo
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
| | - Ouissam El Bakouri
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, C/ M. Aurèlia Capmany 69, 17003, Girona, Spain
| | - Per-Ola Norrby
- Early Product Development, Pharmaceutical Sciences, IMED Biotech Unit AstraZeneca, Pepparedsleden 1, 431 83, Mölndal, Sweden
| | - Henrik Ottosson
- Department of Chemistry - Ångström Laboratory, Uppsala University, Box 530, 751 20, Uppsala, Sweden
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64
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dos Passos Gomes G, Wimmer A, Smith JM, König B, Alabugin IV. CO2 or SO2: Should It Stay, or Should It Go? J Org Chem 2019; 84:6232-6243. [DOI: 10.1021/acs.joc.9b00503] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Gabriel dos Passos Gomes
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32309, United States
| | - Alexander Wimmer
- Institut für Organische Chemie, Universität Regensburg, Universitätsstraße 31, Regensburg 93040, Germany
| | - Joel M. Smith
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32309, United States
| | - Burkhard König
- Institut für Organische Chemie, Universität Regensburg, Universitätsstraße 31, Regensburg 93040, Germany
| | - Igor V. Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32309, United States
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65
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Baranac-Stojanović M, Stojanović M. The effect of two types of dibenzoannulation of pentalene on molecular energies and magnetically induced currents. Phys Chem Chem Phys 2019; 21:3250-3263. [PMID: 30681696 DOI: 10.1039/c8cp07875k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The effect of two types of dibenzo-fusion of pentalene in the singlet and triplet states on its molecular energies and magnetically induced ring currents was examined via density functional calculations. The isomerization energy decomposition analysis (IEDA) together with the calculated aromaticity indices (NICS(1)zz, HOMA and FLUπ), estimation of resonance energies (RE) and extra cyclic resonance energies (ECRE) via the NBO method, and the NICS-XY-scans revealed that the π-electronic system is the most important factor controlling the molecular energies. The [a,f] topology features greater delocalization, which results in two opposing effects: larger ECRE, but weaker π-bonding. The latter is mainly responsible for the higher energy of [a,f]-dibenzopentalene (DBP) (ΔEiso = 21.7 kcal mol-1), with the other effects being σ-orbital and electrostatic interactions. The reversal of energetic stability in the triplet states (ΔEiso = -10.8 kcal mol-1) mainly comes from the reduced Pauli repulsion in [a,f]-DBP, which stabilizes the unpaired spin density over the central trimethylenemethane subunit vs. the central pentalene subunit in [a,e]-DBP. Although the [a,e] topology only reduces the diatropic and paratropic currents of the elementary subunits, benzene and pentalene, the [a,f] topology also creates strong global paratropicity involving the benzene rings. Both DBP isomers are characterized by global and smaller semi-global and local diatropic currents in the triplet state.
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Affiliation(s)
- Marija Baranac-Stojanović
- University of Belgrade - Faculty of Chemistry, Studentski trg 12-16, P.O. Box 158, 11000 Belgrade, Serbia.
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66
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Yadav S, El Bakouri O, Jorner K, Tong H, Dahlstrand C, Solà M, Ottosson H. Exploiting the Aromatic Chameleon Character of Fulvenes for Computational Design of Baird‐Aromatic Triplet Ground State Compounds. Chem Asian J 2019; 14:1870-1878. [DOI: 10.1002/asia.201801821] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Sangeeta Yadav
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Ouissam El Bakouri
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Kjell Jorner
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
| | - Hui Tong
- Department of Chemistry-BMC, Box 576Uppsala University 75123 Uppsala Sweden
| | | | - Miquel Solà
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de QuímicaUniversitat de Girona c/ Maria Aurèlia Capmany 69 17003 Girona Catalonia Spain
| | - Henrik Ottosson
- Department of Chemistry-Ångström Laboratory, Box 523Uppsala University 75120 Uppsala Sweden
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67
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Hughes AM, dos Passos Gomes G, Alabugin IV. Stereoelectronic Influence of a “Spectator” Propargylic Substituent Can Override Aromaticity Effects in Radical Peri-Cyclizations en Route to Expanded Polyaromatics. J Org Chem 2019; 84:1853-1862. [DOI: 10.1021/acs.joc.8b02779] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Audrey M. Hughes
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Gabriel dos Passos Gomes
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Igor V. Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
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68
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Speck F, Rombach D, Wagenknecht HA. N-Arylphenothiazines as strong donors for photoredox catalysis - pushing the frontiers of nucleophilic addition of alcohols to alkenes. Beilstein J Org Chem 2019; 15:52-59. [PMID: 30680038 PMCID: PMC6334793 DOI: 10.3762/bjoc.15.5] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/12/2018] [Indexed: 12/26/2022] Open
Abstract
A new range of N-phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These N-phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated N-phenylphenothiazines were identified to be highly suitable for photoredox catalysis. The dialkylamino substituents of these N-phenylphenothiazines shift the estimated excited state reduction potential up to -3.0 V (vs SCE). These highly reducing properties allow the addition of methanol to α-methylstyrene as less-activated substrate for this type of reaction. Without the help of an additive, the reaction conditions were optimized to achieve a quantitative yield for the Markovnivkov-type addition product after 20 h of irradiation.
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Affiliation(s)
- Fabienne Speck
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - David Rombach
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
| | - Hans-Achim Wagenknecht
- Institute of Organic Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
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69
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Solel E, Kozuch S. Tuning the Spin, Aromaticity, and Quantum Tunneling in Computationally Designed Fulvalenes. J Org Chem 2018; 83:10826-10834. [DOI: 10.1021/acs.joc.8b01541] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ephrath Solel
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel
| | - Sebastian Kozuch
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel
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70
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Oh J, Sung YM, Hong Y, Kim D. Spectroscopic Diagnosis of Excited-State Aromaticity: Capturing Electronic Structures and Conformations upon Aromaticity Reversal. Acc Chem Res 2018; 51:1349-1358. [PMID: 29508985 DOI: 10.1021/acs.accounts.7b00629] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention. The completely reversed aromaticity in the excited state provides direct insight into understanding the photophysical/chemical properties of photoactive materials. In turn, the application of aromatic molecules to photoactive materials has led to numerous studies revealing this aromaticity reversal. However, most studies of excited-state aromaticity have been based on the theoretical point of view. The experimental evaluation of aromaticity in the excited state is still challenging and strenuous because the assessment of (anti)aromaticity with conventional magnetic, energetic, and geometric indices is difficult in the excited state, which practically restricts the extension and application of the concept of excited-state aromaticity. Time-resolved optical spectroscopies can provide a new and alternative avenue to evaluate excited-state aromaticity experimentally while observing changes in the molecular features in the excited states. Time-resolved optical spectroscopies take advantage of ultrafast laser pulses to achieve high time resolution, making them suitable for monitoring ultrafast changes in the excited states of molecular systems. This can provide valuable information for understanding the aromaticity reversal. This Account presents recent breakthroughs in the experimental assessment of excited-state aromaticity and the verification of aromaticity reversal with time-resolved optical spectroscopic measurements. To scrutinize this intriguing and challenging scientific issue, expanded porphyrins have been utilized as the ideal testing platform for investigating aromaticity because they show distinct aromatic and antiaromatic characters with aromaticity-specific spectroscopic features. Expanded porphyrins exhibit perfect aromatic and antiaromatic congener pairs having the same molecular framework but different numbers of π electrons, which facilitates the study of the pure effect of aromaticity by comparative analyses. On the basis of the characteristics of expanded porphyrins, time-resolved electronic and vibrational absorption spectroscopies capture the changes in electronic structure and molecular conformations driven by the change in aromaticity and provide clear evidence for aromaticity reversal in the excited states. The approaches described in this Account pave the way for the development of new and alternative experimental indices for the evaluation of excited-state aromaticity, which will enable overarching and fundamental comprehension of the role of (anti)aromaticity in the stability, dynamics, and reactivity in the excited states with possible implications for practical applications.
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Affiliation(s)
- Juwon Oh
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Young Mo Sung
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Yongseok Hong
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
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71
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Škalamera Đ, Antol I, Mlinarić-Majerski K, Vančik H, Phillips DL, Ma J, Basarić N. Ultrafast Adiabatic Photodehydration of 2-Hydroxymethylphenol and the Formation of Quinone Methide. Chemistry 2018; 24:9426-9435. [PMID: 29677402 DOI: 10.1002/chem.201801543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Indexed: 12/13/2022]
Abstract
The photochemical reactivity of 2-hydroxymethylphenol (1) was investigated experimentally by photochemistry under cryogenic conditions, by detecting reactive intermediates by IR spectroscopy, and by using nanosecond and femtosecond transient absorption spectroscopic methods in solution at room temperature. In addition, theoretical studies were performed to facilitate the interpretation of the experimental results and also to simulate the reaction pathway to obtain a better understanding of the reaction mechanism. The main finding of this work is that photodehydration of 1 takes place in an ultrafast adiabatic photochemical reaction without any clear intermediate, delivering quinone methide (QM) in the excited state. Upon photoexcitation to a higher vibrational level of the singlet excited state, 1 undergoes vibrational relaxation leading to two photochemical pathways, one by which synchronous elimination of H2 O gives QM 2 in its S1 state and the other by which homolytic cleavage of the phenolic O-H bond produces a phenoxyl radical (S0 ). Both are ultrafast processes that occur within a picosecond. The excited state of QM 2 (S1 ) probably deactivates to S0 through a conical intersection to give QM 2 (S0 ), which subsequently delivers benzoxete 4. Elucidation of the reaction mechanisms for the photodehydration of phenols by which QMs are formed is important to tune the reactivity of QMs with DNA and proteins for the potential application of QMs in medicine as therapeutic agents.
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Affiliation(s)
- Đani Škalamera
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia.,Department of Organic Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - Ivana Antol
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
| | - Kata Mlinarić-Majerski
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
| | - Hrvoj Vančik
- Department of Organic Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P.R. China
| | - Jiani Ma
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of, Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, P.R. China
| | - Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
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73
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Adaptive aromaticity in S0 and T1 states of pentalene incorporating 16 valence electron osmium. Commun Chem 2018. [DOI: 10.1038/s42004-018-0018-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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74
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Jorner K, Jahn BO, Bultinck P, Ottosson H. Triplet state homoaromaticity: concept, computational validation and experimental relevance. Chem Sci 2018; 9:3165-3176. [PMID: 29732099 PMCID: PMC5916107 DOI: 10.1039/c7sc05009g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/16/2018] [Indexed: 01/15/2023] Open
Abstract
Conjugation through space can give rise to aromaticity in the lowest excited triplet state, with impact for photochemistry.
Cyclic conjugation that occurs through-space and leads to aromatic properties is called homoaromaticity. Here we formulate the homoaromaticity concept for the triplet excited state (T1) based on Baird's 4n rule and validate it through extensive quantum-chemical calculations on a range of different species (neutral, cationic and anionic). By comparison to well-known ground state homoaromatic molecules we reveal that five of the investigated compounds show strong T1 homoaromaticity, four show weak homoaromaticity and two are non-aromatic. Two of the compounds have previously been identified as excited state intermediates in photochemical reactions and our calculations indicate that they are also homoaromatic in the first singlet excited state. Homoaromaticity should therefore have broad implications in photochemistry. We further demonstrate this by computational design of a photomechanical “lever” that is powered by relief of homoantiaromatic destabilization in the first singlet excited state.
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Affiliation(s)
- Kjell Jorner
- Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , 751 20 Uppsala , Sweden .
| | - Burkhard O Jahn
- Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , 751 20 Uppsala , Sweden . .,SciClus GmbH & Co. KG , Moritz-von-Rohr-Str. 1a , 07745 Jena , Germany
| | - Patrick Bultinck
- Department of Chemistry , Ghent University , Krijgslaan 281 (S3) , 9000 Gent , Belgium .
| | - Henrik Ottosson
- Department of Chemistry - Ångström Laboratory , Uppsala University , Box 523 , 751 20 Uppsala , Sweden .
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75
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Hydrogenated Benzene in Circumstellar Environments: Insights into the Photostability of Super-hydrogenated PAHs. ACTA ACUST UNITED AC 2018. [DOI: 10.3847/1538-4357/aaa977] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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76
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77
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78
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Muñoz-Castro A, Popov IA, Boldyrev AI. Long-range magnetic response of toroidal boron structures: B 16 and [Co@B 16] -/3- species. Phys Chem Chem Phys 2017; 19:26145-26150. [PMID: 28930312 DOI: 10.1039/c7cp04158f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A correlation between the long-range characteristics of the magnetic response of toroidal boron-based structures is given, involving the uncoordinated B16 cluster and the hypercoordinated [Co@B16]-/3- counterparts. It is found that the perfectly symmetrical doubly aromatic systems share common features, involving a continuous shielding region for the orientation-averaged response (isotropic), and a long-ranged shielding cone under a perpendicularly oriented applied field (B). In contrast, the conflicting aromatic structure given by the slightly distorted species, exhibits an enhanced deshielding cone under B, which dominates the isotropic character of the response. In addition, [Mn@B16]- and [Cu@B16]- clusters were evaluated, denoting the role of the coordinated metal atom in such property. This information is valuable to account for a global magnetic response driven by the bonding pattern acting in each respective compound, and for the possible characterization of intermolecular aggregates or extended structures via NMR experiments.
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Affiliation(s)
- Alvaro Muñoz-Castro
- Grupo de Química Inorgánica y Materiales Moleculares, Universidad Autonoma de Chile, El Llano Subercaseaux 2801, Santiago, Chile.
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79
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Baranac-Stojanović M. 4π-Electron B-N Monocycles: Stability and (Anti)aromaticity. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marija Baranac-Stojanović
- Faculty of Chemistry; University of Belgrade; Studentski trg 12-16, P. O. Box 158 11000 Belgrade Serbia
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80
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Ayub R, Papadakis R, Jorner K, Zietz B, Ottosson H. Cyclopropyl Group: An Excited-State Aromaticity Indicator? Chemistry 2017; 23:13684-13695. [PMID: 28683165 DOI: 10.1002/chem.201701404] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Indexed: 01/11/2023]
Abstract
The cyclopropyl (cPr) group, which is a well-known probe for detecting radical character at atoms to which it is connected, is tested as an indicator for aromaticity in the first ππ* triplet and singlet excited states (T1 and S1 ). Baird's rule says that the π-electron counts for aromaticity and antiaromaticity in the T1 and S1 states are opposite to Hückel's rule in the ground state (S0 ). Our hypothesis is that the cPr group, as a result of Baird's rule, will remain closed when attached to an excited-state aromatic ring, enabling it to be used as an indicator to distinguish excited-state aromatic rings from excited-state antiaromatic and nonaromatic rings. Quantum chemical calculations and photoreactivity experiments support our hypothesis; calculated aromaticity indices reveal that openings of cPr substituents on [4n]annulenes ruin the excited-state aromaticity in energetically unfavorable processes. Yet, polycyclic compounds influenced by excited-state aromaticity (e.g., biphenylene), as well as 4nπ-electron heterocycles with two or more heteroatoms represent limitations.
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Affiliation(s)
- Rabia Ayub
- Department of Chemistry-BMC, Uppsala University, Box 576, 751 23, Uppsala, Sweden.,Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Raffaello Papadakis
- Department of Chemistry-BMC, Uppsala University, Box 576, 751 23, Uppsala, Sweden.,Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Kjell Jorner
- Department of Chemistry-BMC, Uppsala University, Box 576, 751 23, Uppsala, Sweden.,Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Burkhard Zietz
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20, Uppsala, Sweden
| | - Henrik Ottosson
- Department of Chemistry-BMC, Uppsala University, Box 576, 751 23, Uppsala, Sweden.,Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 751 20, Uppsala, Sweden
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81
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Ueda M, Jorner K, Sung YM, Mori T, Xiao Q, Kim D, Ottosson H, Aida T, Itoh Y. Energetics of Baird aromaticity supported by inversion of photoexcited chiral [4n]annulene derivatives. Nat Commun 2017; 8:346. [PMID: 28839142 PMCID: PMC5570949 DOI: 10.1038/s41467-017-00382-1] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/20/2017] [Indexed: 11/08/2022] Open
Abstract
For the concept of aromaticity, energetic quantification is crucial. However, this has been elusive for excited-state (Baird) aromaticity. Here we report our serendipitous discovery of two nonplanar thiophene-fused chiral [4n]annulenes Th4 COT Saddle and Th6 CDH Screw , which by computational analysis turned out to be a pair of molecules suitable for energetic quantification of Baird aromaticity. Their enantiomers were separable chromatographically but racemized thermally, enabling investigation of the ring inversion kinetics. In contrast to Th6 CDH Screw , which inverts through a nonplanar transition state, the inversion of Th4 COT Saddle , progressing through a planar transition state, was remarkably accelerated upon photoexcitation. As predicted by Baird's theory, the planar conformation of Th4 COT Saddle is stabilized in the photoexcited state, thereby enabling lower activation enthalpy than that in the ground state. The lowering of the activation enthalpy, i.e., the energetic impact of excited-state aromaticity, was quantified experimentally to be as high as 21-22 kcal mol-1.Baird's rule applies to cyclic π-conjugated molecules in their excited state, yet a quantification of the involved energetics is elusive. Here, the authors show the ring inversion kinetics of two nonplanar and chiral [4n]annulenes to support Baird's rule from an energetic point of view.
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Affiliation(s)
- Michihisa Ueda
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
| | - Kjell Jorner
- Department of Chemistry – Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20 Sweden
| | - Young Mo Sung
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749 Korea
| | - Tadashi Mori
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 Japan
| | - Qi Xiao
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 120-749 Korea
| | - Henrik Ottosson
- Department of Chemistry – Ångström Laboratory, Uppsala University, Box 523, Uppsala, 751 20 Sweden
| | - Takuzo Aida
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Yoshimitsu Itoh
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan
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82
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Electronic properties and aromaticity of substituted diphenylfulvenes in the ground (S0) and excited (T1) states. Struct Chem 2017. [DOI: 10.1007/s11224-017-0995-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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83
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Stephansen AB, Sølling TI. Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2017; 4:044008. [PMID: 28345010 PMCID: PMC5336472 DOI: 10.1063/1.4977735] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 02/16/2017] [Indexed: 05/05/2023]
Abstract
The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly) allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped) S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3) is found to undergo internal conversion in the triplet manifold within ≈100-150 fs (toluene) or ≈180-200 fs (p-xylene) as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.
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Affiliation(s)
- Anne B Stephansen
- Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 København Ø, Denmark
| | - Theis I Sølling
- Department of Chemistry, University of Copenhagen , Universitetsparken 5, DK-2100 København Ø, Denmark
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84
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Papadopoulos AG, Charistos ND, Muñoz-Castro A. Magnetic Response of Aromatic Rings Under Rotation: Aromatic Shielding Cone of Benzene Upon Different Orientations of the Magnetic Field. Chemphyschem 2017; 18:1499-1502. [DOI: 10.1002/cphc.201700279] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Indexed: 12/22/2022]
Affiliation(s)
- A. G. Papadopoulos
- Aristotle University of Thessaloniki; Department of Chemistry; Laboratory of Applied Quantum Chemistry; Thessaloniki 54 124 Greece
| | - N. D. Charistos
- Aristotle University of Thessaloniki; Department of Chemistry; Laboratory of Applied Quantum Chemistry; Thessaloniki 54 124 Greece
| | - A. Muñoz-Castro
- Grupo de Química Inorgánica y Materiales Moleculares; Universidad Autonoma de Chile, El Llano Subercaseaux; 2801 Santiago Chile
- Doctorado en Fisicoquímica Molecular; Universidad Andres Bello; Av. Republica 275 Santiago Chile
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85
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Estévez-Fregoso M, Hernández-Trujillo J. Electron delocalization and electron density of small polycyclic aromatic hydrocarbons in singlet excited states. Phys Chem Chem Phys 2017; 18:11792-9. [PMID: 26795361 DOI: 10.1039/c5cp06993a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The four lowest singlet electronic states of benzene, the acenes from naphthalene to pentacene, phenanthrene and pyrene were studied by means of theoretical methods. Their vertical excitation energies from the ground electronic states were computed at the CASPT2 approximation. As an attempt to explain the trends observed in the excitation energies, several descriptors based on the electron density were used and the similarity of these molecules with their ground state counterparts was analyzed. It was found that the changes of the topological properties at the C-C bond critical points do not explain the decreasing trends for the excitation energies with the increase of the number of rings, in part because the small changes that take place in the electron density occur above and below the molecular plane. A similarity index based on electron delocalization between quantum topological atoms was defined to compare a molecule in two different electronic states. It was found that, mainly for the acenes, this index goes in line with the excitation energies to the first excited state. Implications of the changes in electron delocalization on the aromatic character of these molecules are also discussed. In general, local aromaticity decreases upon excitation.
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Affiliation(s)
- Mar Estévez-Fregoso
- Facultad de Química, Universidad Nacional Autónoma de México, Circuito Escolar, Cd. Universitaria, 04510, México, D.F., Mexico.
| | - Jesús Hernández-Trujillo
- Facultad de Química, Universidad Nacional Autónoma de México, Circuito Escolar, Cd. Universitaria, 04510, México, D.F., Mexico.
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86
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Denisova AV, Tibbelin J, Emanuelsson R, Ottosson H. A Computational Investigation of the Substituent Effects on Geometric, Electronic, and Optical Properties of Siloles and 1,4-Disilacyclohexa-2,5-dienes. Molecules 2017; 22:E370. [PMID: 28264524 PMCID: PMC6155320 DOI: 10.3390/molecules22030370] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/16/2017] [Accepted: 02/20/2017] [Indexed: 11/17/2022] Open
Abstract
Thirty two differently substituted siloles 1a-1p and 1,4-disilacyclohexa-2,5-dienes 2a-2p were investigated by quantum chemical calculations using the PBE0 hybrid density functional theory (DFT) method. The substituents included σ-electron donating and withdrawing, as well as π-electron donating and withdrawing groups, and their effects when placed at the Si atom(s) or at the C atoms were examined. Focus was placed on geometries, frontier orbital energies and the energies of the first allowed electronic excitations. We analyzed the variation in energies between the orbitals which correspond to HOMO and LUMO for the two parent species, here represented as ΔεHL, motivated by the fact that the first allowed transitions involve excitation between these orbitals. Even though ΔεHL and the excitation energies are lower for siloles than for 1,4-disilacyclohexa-2,5-dienes the latter display significantly larger variations with substitution. The ΔεHL of the siloles vary within 4.57-5.35 eV (ΔΔεHL = 0.78 eV) while for the 1,4-disilacyclohexa-2,5-dienes the range is 5.49-7.15 eV (ΔΔεHL = 1.66 eV). The excitation energy of the first allowed transitions display a moderate variation for siloles (3.60-4.41 eV) whereas the variation for 1,4-disilacyclohexa-2,5-dienes is nearly doubled (4.69-6.21 eV). Cyclobutadisiloles combine the characteristics of siloles and 1,4-disilacyclohexa-2,5-diene by having even lower excitation energies than siloles yet also extensive variation in excitation energies to substitution of 1,4-disilacyclohexa-2,5-dienes (3.47-4.77 eV, variation of 1.30 eV).
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Affiliation(s)
- Aleksandra V Denisova
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden.
| | - Julius Tibbelin
- Department of Chemistry-BMC, Uppsala University, Box 576, 75123 Uppsala, Sweden.
| | - Rikard Emanuelsson
- Nanotechnology and Functional Materials, Department of Engineering Sciences, Uppsala University, Box 534, 75121 Uppsala, Sweden.
| | - Henrik Ottosson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden.
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87
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Zilberg S, Dick B. Less stable tautomers form stronger hydrogen bonds: the case of water complexes. Phys Chem Chem Phys 2017; 19:25086-25094. [PMID: 28880041 DOI: 10.1039/c7cp04105e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Hydrogen bonding in cyclic complexes of water with tautomeric pairs of molecules M0 and M1 is calculated to be stronger by more than 25% for the less stable tautomer M1 in all cases where the energy gap between the two tautomers is large (ΔE(M0 − M1) > 10 kcal mol−1).
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Affiliation(s)
- Shmuel Zilberg
- Chemical Sciences Department
- Ariel University
- Ariel 40700
- Israel
| | - Bernhard Dick
- Institute of Physical and Theoretical Chemistry
- University of Regensburg
- 93040 Regensburg
- Germany
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88
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Muñoz-Castro A. The shielding cone in spherical aromatic structures: insights from models for spherical 2(N + 1)2 aromatic fullerenes. Phys Chem Chem Phys 2017; 19:12633-12636. [DOI: 10.1039/c7cp01870c] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The shielding cone in spherical aromatic fullerenes is of long-range character and permits multiple orientations.
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Affiliation(s)
- Alvaro Muñoz-Castro
- Grupo de Química Inorgánica y Materiales Moleculares
- Universidad Autonoma de Chile
- Santiago
- Chile
- Relativistic Molecular Physics (ReMoPh) Group
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89
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Nishina N, Mutai T, Aihara JI. Excited-State Intramolecular Proton Transfer and Global Aromaticity. J Phys Chem A 2016; 121:151-161. [DOI: 10.1021/acs.jpca.6b11684] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Naoko Nishina
- Department of Chemistry,
Faculty of Science, Shizuoka University, Oya, Shizuoka 422-8529, Japan
| | - Toshiki Mutai
- Department
of Materials and Environmental Science, Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Jun-ichi Aihara
- Department of Chemistry,
Faculty of Science, Shizuoka University, Oya, Shizuoka 422-8529, Japan
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90
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Sung YM, Oh J, Cha WY, Kim W, Lim JM, Yoon MC, Kim D. Control and Switching of Aromaticity in Various All-Aza-Expanded Porphyrins: Spectroscopic and Theoretical Analyses. Chem Rev 2016; 117:2257-2312. [DOI: 10.1021/acs.chemrev.6b00313] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Young Mo Sung
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
| | - Juwon Oh
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
| | - Won-Young Cha
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
| | - Woojae Kim
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
| | - Jong Min Lim
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
- Physical
and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Min-Chul Yoon
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
- Manufacturing
Engineering Team, Memory Manufacturing Operation Center, Samsung Electronics, Samsungjeonja-ro 1, Hwasung-si, Gyeonggi-do 18448, South Korea
| | - Dongho Kim
- Spectroscopy
Laboratory for Functional π-Electronic Systems and Department
of Chemistry, Yonsei University, Seoul 120-749, South Korea
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91
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Metal-free photochemical silylations and transfer hydrogenations of benzenoid hydrocarbons and graphene. Nat Commun 2016; 7:12962. [PMID: 27708336 PMCID: PMC5059713 DOI: 10.1038/ncomms12962] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/19/2016] [Indexed: 01/13/2023] Open
Abstract
The first hydrogenation step of benzene, which is endergonic in the electronic ground state (S0), becomes exergonic in the first triplet state (T1). This is in line with Baird's rule, which tells that benzene is antiaromatic and destabilized in its T1 state and also in its first singlet excited state (S1), opposite to S0, where it is aromatic and remarkably unreactive. Here we utilized this feature to show that benzene and several polycyclic aromatic hydrocarbons (PAHs) to various extents undergo metal-free photochemical (hydro)silylations and transfer-hydrogenations at mild conditions, with the highest yield for naphthalene (photosilylation: 21%). Quantum chemical computations reveal that T1-state benzene is excellent at H-atom abstraction, while cyclooctatetraene, aromatic in the T1 and S1 states according to Baird's rule, is unreactive. Remarkably, also CVD-graphene on SiO2 is efficiently transfer-photohydrogenated using formic acid/water mixtures together with white light or solar irradiation under metal-free conditions. Baird's rules say that the first triplet state of benzene displays antiaromatic character. Here, the authors exploit this to show that aromatic molecules can undergo rapid transfer hydrogenation or silylations without the need for metal catalysts when photochemcially excited into this state.
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92
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Sung YM, Oh J, Naoda K, Lee T, Kim W, Lim M, Osuka A, Kim D. A Description of Vibrational Modes in Hexaphyrins: Understanding the Aromaticity Reversal in the Lowest Triplet State. Angew Chem Int Ed Engl 2016; 55:11930-4. [DOI: 10.1002/anie.201603631] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Young Mo Sung
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Juwon Oh
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Koji Naoda
- Department of Chemistry, Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Taegon Lee
- Department of Chemistry and Chemistry Institute for Functional Materials; Pusan National University; Busan 609-735 Korea
| | - Woojae Kim
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials; Pusan National University; Busan 609-735 Korea
| | - Atsuhiro Osuka
- Department of Chemistry, Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
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93
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Sung YM, Oh J, Naoda K, Lee T, Kim W, Lim M, Osuka A, Kim D. A Description of Vibrational Modes in Hexaphyrins: Understanding the Aromaticity Reversal in the Lowest Triplet State. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603631] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Young Mo Sung
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Juwon Oh
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Koji Naoda
- Department of Chemistry, Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Taegon Lee
- Department of Chemistry and Chemistry Institute for Functional Materials; Pusan National University; Busan 609-735 Korea
| | - Woojae Kim
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials; Pusan National University; Busan 609-735 Korea
| | - Atsuhiro Osuka
- Department of Chemistry, Graduate School of Science; Kyoto University; Sakyo-ku Kyoto 606-8502 Japan
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-electronic systems and Department of Chemistry; Yonsei University; Seoul 120-749 Korea
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94
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El Bakouri O, Poater J, Feixas F, Solà M. Exploring the validity of the Glidewell–Lloyd extension of Clar’s π-sextet rule: assessment from polycyclic conjugated hydrocarbons. Theor Chem Acc 2016. [DOI: 10.1007/s00214-016-1970-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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95
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Sundholm D, Fliegl H, Berger RJ. Calculations of magnetically induced current densities: theory and applications. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2016. [DOI: 10.1002/wcms.1270] [Citation(s) in RCA: 163] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Dage Sundholm
- Department of Chemistry; University of Helsinki; Helsinki Finland
| | - Heike Fliegl
- Centre for Theoretical and Computational Chemistry (CTCC), Department of Chemistry; University of Oslo; Oslo Norway
| | - Raphael J.F. Berger
- Paris-Lodron University of Salzburg; Chemistry of Materials; Salzburg Austria
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96
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Oh J, Sung YM, Kim W, Mori S, Osuka A, Kim D. Aromaticity Reversal in the Lowest Excited Triplet State of Archetypical Möbius Heteroannulenic Systems. Angew Chem Int Ed Engl 2016; 55:6487-91. [DOI: 10.1002/anie.201602083] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 03/22/2016] [Indexed: 01/13/2023]
Affiliation(s)
- Juwon Oh
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Young Mo Sung
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Woojae Kim
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Shigeki Mori
- Department of Chemistry; Graduated School of Science; Kyoto University; Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of Chemistry; Graduated School of Science; Kyoto University; Kyoto 606-8502 Japan
| | - Dongho Kim
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
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97
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Oh J, Sung YM, Kim W, Mori S, Osuka A, Kim D. Aromaticity Reversal in the Lowest Excited Triplet State of Archetypical Möbius Heteroannulenic Systems. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201602083] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Juwon Oh
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Young Mo Sung
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Woojae Kim
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
| | - Shigeki Mori
- Department of Chemistry; Graduated School of Science; Kyoto University; Kyoto 606-8502 Japan
| | - Atsuhiro Osuka
- Department of Chemistry; Graduated School of Science; Kyoto University; Kyoto 606-8502 Japan
| | - Dongho Kim
- Department of Chemistry; Spectroscopy Laboratory for Functional π-Electronic Systems; Yonsei University; Seoul 120-749 Korea
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98
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Jorner K, Feixas F, Ayub R, Lindh R, Solà M, Ottosson H. Analysis of a Compound Class with Triplet States Stabilized by Potentially Baird Aromatic [10]Annulenyl Dicationic Rings. Chemistry 2016; 22:2793-800. [DOI: 10.1002/chem.201504924] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Kjell Jorner
- Department of Chemistry-BMC; Uppsala University; Box 576 75123 Uppsala Sweden
| | - Ferran Feixas
- Institut de Química Computacional i Catàlisi (IQCC) and; Departament de Química; Universitat de Girona; Campus de Montilivi s/n 17071 Girona Catalonia Spain
| | - Rabia Ayub
- Department of Chemistry-BMC; Uppsala University; Box 576 75123 Uppsala Sweden
| | - Roland Lindh
- Department of Chemistry-Ångström Laboratory; Uppsala University; Box 518 75120 Uppsala Sweden
- Uppsala Center for Computational Chemistry-UC3; Uppsala University; Box 518 75120 Uppsala Sweden
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi (IQCC) and; Departament de Química; Universitat de Girona; Campus de Montilivi s/n 17071 Girona Catalonia Spain
| | - Henrik Ottosson
- Department of Chemistry-BMC; Uppsala University; Box 576 75123 Uppsala Sweden
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99
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Denisova AV, Emanuelsson R, Ottosson H. Expanding the (cross-)hyperconjugation of 1,4-disilacyclohexa-2,5-dienes to larger monomers and oligomers: a computational investigation. RSC Adv 2016. [DOI: 10.1039/c6ra02732f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
DFT calculations are used to study molecules that can be regarded as expanded 1,4-disilacyclohexa-2,5-dienes as well as oligomers based on these or 1,4-disilacyclohexa-2,5-diene with the aim to identify systems with extended (cross)-hyperconjugation.
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Affiliation(s)
- Aleksandra V. Denisova
- Department of Chemistry – BMC
- Uppsala University
- 751 23 Uppsala
- Sweden
- Department of Chemistry – Ångström Laboratory
| | - Rikard Emanuelsson
- Nanotechnology and Functional Materials
- Department of Engineering Sciences
- Uppsala University
- 751 21 Uppsala
- Sweden
| | - Henrik Ottosson
- Department of Chemistry – BMC
- Uppsala University
- 751 23 Uppsala
- Sweden
- Department of Chemistry – Ångström Laboratory
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100
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Mohamed RK, Mondal S, Jorner K, Delgado TF, Lobodin VV, Ottosson H, Alabugin IV. The Missing C1-C5 Cycloaromatization Reaction: Triplet State Antiaromaticity Relief and Self-Terminating Photorelease of Formaldehyde for Synthesis of Fulvenes from Enynes. J Am Chem Soc 2015; 137:15441-50. [PMID: 26536479 DOI: 10.1021/jacs.5b07448] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The last missing example of the four archetypical cycloaromatizations of enediynes and enynes was discovered by combining a twisted alkene excited state with a new self-terminating path for intramolecular conversion of diradicals into closed-shell products. Photoexcitation of aromatic enynes to a twisted alkene triplet state creates a unique stereoelectronic situation, which is facilitated by the relief of excited state antiaromaticity of the benzene ring. This enables the usually unfavorable 5-endo-trig cyclization and merges it with 5-exo-dig closure. The 1,4-diradical product of the C1-C5 cyclization undergoes internal H atom transfer that is coupled with the fragmentation of an exocyclic C-C bond. This sequence provides efficient access to benzofulvenes from enynes and expands the utility of self-terminating aromatizing enyne cascades to photochemical reactions. The key feature of this self-terminating reaction is that, despite the involvement of radical species in the key cyclization step, no external radical sources or quenchers are needed to provide the products. In these cascades, both radical centers are formed transiently and converted to the closed-shell products via intramolecular H-transfer and C-C bond fragmentation. Furthermore, incorporating C-C bond cleavage into the photochemical self-terminating cyclizations of enynes opens a new way for the use of alkenes as alkyne equivalents in organic synthesis.
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Affiliation(s)
| | | | - Kjell Jorner
- Department of Chemistry - BMC, Uppsala University , Box 576, 751 23 Uppsala, Sweden
| | | | - Vladislav V Lobodin
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States.,Future Fuels Institute, Florida State University , Tallahassee, Florida 32310, United States
| | - Henrik Ottosson
- Department of Chemistry - BMC, Uppsala University , Box 576, 751 23 Uppsala, Sweden
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