1
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Sokolova AD, Platonov DN, Belyy AY, Salikov RF, Erokhin KS, Tomilov YV. The Antiaromatic Nucleophilic Substitution Reaction (S NAAr) in Cycloheptatrienyl-Anion Containing Zwitterions with a Möbius-Aromatic Intermediate. Org Lett 2024; 26:5877-5882. [PMID: 38958743 DOI: 10.1021/acs.orglett.4c01446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Antiaromatic nucleophilic substitution reactions in cycloheptatrienide pyridinium and phosphonium zwitterions with initial formation of a cycloheptatetraene intermediate are explored. The mechanism was supported by quantum chemical calculations, first-order reaction kinetics, and high-resolution mass spectrometry. The pyridinium zwitterion exhibited weak antiaromaticity, whereas the intermediate displayed Möbius aromaticity, as evidenced by nuclear independent chemical shift values and the shape of its HOMO. This study represents the eighth confirmed instance of a Möbius-aromatic organic species in its ground state.
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Affiliation(s)
- Alena D Sokolova
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Dmitry N Platonov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Alexander Yu Belyy
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Rinat F Salikov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Kirill S Erokhin
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
| | - Yury V Tomilov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation
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2
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Zhou Z, Johnson MA, Wei Z, Bühringer MU, Garner MH, Tykwinski R, Petrukhina MA. Bending a Cumulene with Electrons: Stepwise Chemical Reduction and Structural Study of a Tetraaryl[4]Cumulene. Chemistry 2024; 30:e202304145. [PMID: 38433113 DOI: 10.1002/chem.202304145] [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: 01/30/2024] [Revised: 03/02/2024] [Accepted: 03/03/2024] [Indexed: 03/05/2024]
Abstract
Chemical reduction of a [4]cumulene with cesium metal was explored, and the structural changes stemming from electron acquisition are detailed using X-ray crystallography. It is found that the [4]cumulene undergoes dramatic geometric changes upon stepwise reduction, including bending of the cumulenic core and twisting of the endgroups from orthogonal to planar. The structural deformation is consistent with early theoretical reports that suggest that the twisting should occur upon reduction of both even and odd [n]cumulenes. The current results, on the other hand, are inconsistent with a previous experimental study of a [3]cumulene in which the predicted twisting is not observed upon reduction. DFT calculations reveal that the barrier to deformation is an order of magnitude lower in a [3]cumulene than a [4]cumulene, allowing the barrier to be overcome in the solid-state.
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Affiliation(s)
- Zheng Zhou
- Department of Chemistry, University at Albany, State University of New York, Albany, NY-12222, USA
| | - Matthew A Johnson
- Department of Chemistry, University of Alberta, Edmonton, AB-T6G 2G2, Canada
| | - Zheng Wei
- Department of Chemistry, University at Albany, State University of New York, Albany, NY-12222, USA
| | - Martina U Bühringer
- Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Nikolaus-Fiebiger Str. 10, 91058, Erlangen, Germany
| | - Marc H Garner
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Rik Tykwinski
- Department of Chemistry, University of Alberta, Edmonton, AB-T6G 2G2, Canada
| | - Marina A Petrukhina
- Department of Chemistry, University at Albany, State University of New York, Albany, NY-12222, USA
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3
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Zhao D, Zhao Y, Xu T, He X, Hu S, Ayers PW, Liu S. Chiral Jahn-Teller Distortion in Quasi-Planar Boron Clusters. Molecules 2024; 29:1624. [PMID: 38611903 PMCID: PMC11013085 DOI: 10.3390/molecules29071624] [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: 02/09/2024] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/14/2024] Open
Abstract
In this work, we have observed that some chiral boron clusters (B16-, B20-, B24-, and B28-) can simultaneously have helical molecular orbitals and helical spin densities; these seem to be the first compounds discovered to have this intriguing property. We show that chiral Jahn-Teller distortion of quasi-planar boron clusters drives the formation of the helical molecular spin densities in these clusters and show that elongation/enhancement in helical molecular orbitals can be achieved by simply adding more building blocks via a linker. Aromaticity of these boron clusters is discussed. Chiral boron clusters may find potential applications in spintronics, such as molecular magnets.
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Affiliation(s)
- Dongbo Zhao
- Institute of Biomedical Research, Yunnan University, Kunming 650500, China
| | - Yilin Zhao
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4M1, Canada
| | - Tianlv Xu
- College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China
| | - Xin He
- Qingdao Institute for Theoretical and Computational Sciences, Shandong University, Qingdao 266237, China
| | - Shankai Hu
- Institute of Biomedical Research, Yunnan University, Kunming 650500, China
| | - Paul W. Ayers
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON L8S 4M1, Canada
| | - Shubin Liu
- Research Computing Center, University of North Carolina, Chapel Hill, NC 27599-3420, USA
- Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, USA
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4
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Parvathy P, Parameswaran P. Organometallic Allene [(μ-C)(Fe(CO) 4 ) 2 ]: Bridging Carbon Showing Transformation from Classical Electron-Sharing Bonding to Double σ-Donor and Double π-Acceptor Ligation. Chemphyschem 2023; 24:e202300528. [PMID: 37563865 DOI: 10.1002/cphc.202300528] [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: 08/05/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/12/2023]
Abstract
Allenes (R2 C=C=CR2 ) have been traditionally perceived to feature localized orthogonal π-bonds between the carbon centres. We have carried out quantum-mechanical studies of the organometallic allenes envisioned by the isolobal replacement of the terminal CH2 groups by the d8 Fe(CO)4 fragment. Our studies have identified two organometallic allenes viz. D2d symmetric [(μ-C)(Fe(CO)4 )2 ] (2) and D3 symmetric [(μ-C)(Fe(CO)4 )2 ] (3) with trigonal bipyramidal coordination at the Fe atoms. Compound 2 features the bridging carbon atom in an equatorial position with respect to the ligands on the TM centre, while 3 features the central carbon atom in an axial position. The bis-pseudoallylic anionic delocalisation proposed in the C2-C1-C3 spine of organic allene is retained in the organometallic allene 2, and is transformed to a typical three-centre bis-allylic anionic delocalisation in the organometallic allene 3. The topological analysis of electron density also indicates a bis-allylic anionic type delocalisation in the organometallic allenes. The quantitative bonding analysis using the EDA-NOCV method suggests a transition from classical electron-sharing bonding between the central carbon atom and the terminal groups in 1 to donor-acceptor bonding in 3. Meanwhile, both electron-sharing and donor-acceptor bonding models are found to be probable heuristic bonding representations in the organometallic allene 2.
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Affiliation(s)
- Parameswaran Parvathy
- Department of Chemistry, National Institute of Technology Calicut, Kerala, 673601, India
| | - Pattiyil Parameswaran
- Department of Chemistry, National Institute of Technology Calicut, Kerala, 673601, India
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5
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Bro-Jørgensen W, Solomon GC. Understanding Current Density in Molecules Using Molecular Orbitals. J Phys Chem A 2023; 127:9003-9012. [PMID: 37856785 PMCID: PMC10627148 DOI: 10.1021/acs.jpca.3c04631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/29/2023] [Indexed: 10/21/2023]
Abstract
While the use of molecular orbitals (MOs) and their isosurfaces to explain physical phenomena in chemical systems is a time-honored tool, we show that the nodes are an equally important component for understanding the current density through single-molecule junctions. We investigate three different model systems consisting of an alkane, alkene, and even [n]cumulene and show that we can explain the form of the current density using the MOs of the molecule. Essentially, the MOs define the region in which current can flow and their gradients define the direction in which current flows within that region. We also show that it is possible to simplify the current density for improved understanding by either partitioning the current density into more chemically intuitive parts, such as σ- and π-systems, or by filtering out MOs with negligible contributions to the overall current density. Our work highlights that it is possible to infer a non-equilibrium property (current density) given only equilibrium properties (MOs and their gradients), and this, in turn, grants deeper insight into coherent electron transport.
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Affiliation(s)
- William Bro-Jørgensen
- Department
of Chemistry and Nano-Science Center, University
of Copenhagen, Universitetsparken
5, DK-2100 Copenhagen, Denmark
| | - Gemma C. Solomon
- Department
of Chemistry and Nano-Science Center, University
of Copenhagen, Universitetsparken
5, DK-2100 Copenhagen, Denmark
- NNF
Quantum Computing Programme, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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6
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Sepehri A, Li RR, Hoffmann MR. Riemannian Trust Region Method for Minimization of the Fourth Central Moment for Localized Molecular Orbitals. J Phys Chem A 2023. [PMID: 37285307 DOI: 10.1021/acs.jpca.3c01295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The importance of localized molecular orbitals (MOs) in correlation treatments beyond mean-field calculation and in the illustration of chemical bonding (and antibonding) can hardly be overstated. However, the generation of orthonormal localized occupied MOs is significantly more straightforward than obtaining orthonormal localized virtual MOs. Orthonormal MOs allow facile use of highly efficient group theoretical methods (e.g., graphical unitary group approach) for calculation of Hamiltonian matrix elements in multireference configuration interaction calculations (such as MRCISD) and in quasi-degenerate perturbation treatments, such as the Generalized Van Vleck Perturbation Theory. Moreover, localized MOs can elucidate qualitative understanding of bonding in molecules, in addition to high-accuracy quantitative descriptions. We adopt the powers of the fourth moment cost function introduced by Jørgensen and coworkers. Because the fourth moment cost functions are prone to having multiple negative Hessian eigenvalues when starting from easily available canonical (or near-canonical) MOs, standard optimization algorithms can fail to obtain the orbitals of the virtual or partially occupied spaces. To overcome this drawback, we applied a trust region algorithm on an orthonormal Riemannian manifold with an approximate retraction from the tangent space built into the first and second derivatives of the cost function. Moreover, the Riemannian trust region outer iterations were coupled to truncated Conjugate Gradient inner loops, which avoided any costly solutions of simultaneous linear equations or eigenvector/eigenvalue solutions. Numerical examples are provided on model systems, including the high-connectivity H10 set in 1-, 2-, and 3-dimensional arrangements, and on a chemically realistic description of cyclobutadiene (c-C4H4) and the propargyl radical (C3H3). In addition to demonstrating the algorithm on occupied and virtual blocks of orbitals, the method is also shown to work on the active space at the MCSCF level of theory.
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Affiliation(s)
- Aliakbar Sepehri
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202-9024, United States
| | - Run R Li
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Mark R Hoffmann
- Chemistry Department, University of North Dakota, Grand Forks, North Dakota 58202-9024, United States
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7
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Lenko I, Alayrac C, Bożek I, Witulski B. 1,3-Butadiynamides the Ethynylogous Ynamides: Synthesis, Properties and Applications in Heterocyclic Chemistry. Molecules 2023; 28:molecules28114564. [PMID: 37299038 DOI: 10.3390/molecules28114564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 05/30/2023] [Accepted: 06/01/2023] [Indexed: 06/12/2023] Open
Abstract
1,3-butadiynamides-the ethynylogous variants of ynamides-receive considerable attention as precursors of complex molecular scaffolds for organic and heterocyclic chemistry. The synthetic potential of these C4-building blocks reveals itself in sophisticated transition-metal catalyzed annulation reactions and in metal-free or silver-mediated HDDA (Hexa-dehydro-Diels-Alder) cycloadditions. 1,3-Butadiynamides also gain significance as optoelectronic materials and in less explored views on their unique helical twisted frontier molecular orbitals (Hel-FMOs). The present account summarizes different methodologies for the synthesis of 1,3-butadiynamides followed by the description of their molecular structure and electronic properties. Finally, the surprisingly rich chemistry of 1,3-butadiynamides as versatile C4-building blocks in heterocyclic chemistry is reviewed by compiling their exciting reactivity, specificity and opportunities for organic synthesis. Besides chemical transformations and use in synthesis, a focus is set on the mechanistic understanding of the chemistry of 1,3-butadiynamides-suggesting that 1,3-butadiynamides are not just simple alkynes. These ethynylogous variants of ynamides have their own molecular character and chemical reactivity and reflect a new class of remarkably useful compounds.
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Affiliation(s)
- Illia Lenko
- Laboratoire de Chimie Moléculaire et Thio-Organique (LCMT), CNRS UMR 6507, ENSICAEN & UNICAEN, Normandie University, 6 Bd Maréchal Juin, 14050 Caen, France
| | - Carole Alayrac
- Laboratoire de Chimie Moléculaire et Thio-Organique (LCMT), CNRS UMR 6507, ENSICAEN & UNICAEN, Normandie University, 6 Bd Maréchal Juin, 14050 Caen, France
| | - Igor Bożek
- Laboratoire de Chimie Moléculaire et Thio-Organique (LCMT), CNRS UMR 6507, ENSICAEN & UNICAEN, Normandie University, 6 Bd Maréchal Juin, 14050 Caen, France
| | - Bernhard Witulski
- Laboratoire de Chimie Moléculaire et Thio-Organique (LCMT), CNRS UMR 6507, ENSICAEN & UNICAEN, Normandie University, 6 Bd Maréchal Juin, 14050 Caen, France
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8
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Muchova E, Hollas D, Holland DMP, Bacellar C, Leroy L, Barillot TR, Longetti L, Coreno M, de Simone M, Grazioli C, Chergui M, Ingle RA. Jahn-Teller effects in initial and final states: high-resolution X-ray absorption, photoelectron and Auger spectroscopy of allene. Phys Chem Chem Phys 2023; 25:6733-6745. [PMID: 36799466 DOI: 10.1039/d2cp05299g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Carbon K-edge resonant Auger spectra of gas-phase allene following excitation of the pre-edge 1s → π* transitions are presented and analysed with the support of EOM-CCSD/cc-pVTZ calculations. X-Ray absorption (XAS), X-ray photoelectron (XPS), valence band and non-resonant Auger spectra are also reanalysed with a series of computational approaches. The results presented demonstrate the importance of including nuclear ensemble effects for simulating X-ray observables and as an effective strategy for capturing Jahn-Teller effects in spectra.
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Affiliation(s)
- Eva Muchova
- Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic
| | - Daniel Hollas
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | | | - Camila Bacellar
- Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland
| | - Ludmila Leroy
- Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland
| | - Thomas R Barillot
- Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland
| | - Luca Longetti
- Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland
| | - Marcello Coreno
- ISM-CNR, Istituto di Struttura dei Materiali, LD2 Unit, 34149 Trieste, Italy
| | | | - Cesare Grazioli
- IOM-CNR, Istituto Officina dei Materiali, 34149 Trieste, Italy
| | - Majed Chergui
- Laboratoire de Spectroscopie Ultrarapide, Ecole Polytechnique Fédérale de Lausanne, ISIC, FSB, CH-1015 Lausanne, Switzerland
| | - Rebecca A Ingle
- Department of Chemistry, 20 Gordon Street, London, WC1H 0AJ, UK.
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9
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Hu Y, Zhou Y, Ye J, Yuan S, Xiao Z, Shi J, Yang Y, Solomon GC, Hong W. σ-dominated charge transport in sub-nanometer molecular junctions. FUNDAMENTAL RESEARCH 2022. [DOI: 10.1016/j.fmre.2022.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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10
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Pancharatna PD, Dar SH, Chowdhury UD, Balakrishnarajan MM. Anatomy of Classical Boron-Boron Bonding: Overlap and sp Dissonance. J Phys Chem A 2022; 126:3219-3228. [PMID: 35579966 DOI: 10.1021/acs.jpca.2c01981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Classical bonding is predominantly understood using the insipid spn hybridization for σ-bonds as well as π bonds and their delocalized variants. Because hybridization ignores intricate differences in the energy and size of valence atomic orbitals, its naïve application to classically bonded boron atoms leads to numerous surprises in bond strengths, frontier MOs/bands, and even geometry. Here we show that the sp dissonance caused by size mismatch between the valence s and p orbitals of boron plays a crucial role in its bonding, subtly distinct from that of carbon and silicon. Unlike the heavier p block elements, boron prefers to actively engage its compact 2s orbitals in bonding. This leads to the overreach of p-p σ-type overlap that reduces its magnitude in the entire B─B bonding range. Consequently, the π-type overlap remains substantial, making its electronic structure visibly distinct in saturated and unsaturated regimes. The deltahedral frameworks offer a compromise by breaking this symmetry-enforced dichotomy of classical σ- and π-type bonding and following alternate electron counts that suit the electron deficiency of the boron. The pathological anatomy of classical B─B σ-bonding also explains the origins of puzzling metallic character and disorder in their classical boride networks even with ideal electron count, unlike deltahedral borides. The implications of sp dissonance are illustrated in classical boron networks of various hybridizations, explaining the unusual preference for unique sp3 lattice with strained four-membered rings in CrB4, origins of observed σ holes in MgB2 that lead to its superconducting nature, and the absence of Peierls distortion in LiB.
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Affiliation(s)
| | - Sohail H Dar
- Department of Chemistry, Pondicherry University, Pondicherry, India 605 014
| | - Unmesh D Chowdhury
- Department of Chemistry, National Institute of Science Education and Research-Bhubaneswar, an OCC of Homi Bhabha National Institute, Odisha, India 752050
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11
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Ideböhn V, Sterling AJ, Wallner M, Olsson E, Squibb RJ, Miniotaite U, Forsmalm E, Forsmalm M, Stranges S, Dyke JM, Duarte F, Eland JHD, Feifel R. Single photon double and triple ionization of allene. Phys Chem Chem Phys 2022; 24:786-796. [PMID: 34927639 DOI: 10.1039/d1cp04666g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double and triple ionization of allene are investigated using electron-electron, ion-ion, electron-electron-ion and electron-electron-ion-ion (ee, ii, eei, eeii) coincidence spectroscopies at selected photon energies. The results provide supporting evidence for a previously proposed roaming mechanism in H3+ formation by double ionization. The lowest vertical double ionization energy is found to be 27.9 eV, while adiabatic double ionization is not accessed by vertical ionization at the neutral geometry. The triple ionization energy is found to be close to 50 eV in agreement with theoretical predictions. The doubly charged parent ion is stable up to about 2 eV above the threshold, after which dissociations by charge separation and by double charge retention occur with comparable intensities. Fragmentation to H+ + C3H3+ starts immediately above the threshold as a slow (metastable) decay with 130.5 ± 9.9 ns mean lifetime.
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Affiliation(s)
- Veronica Ideböhn
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Alistair J Sterling
- Department of Chemistry, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - Måns Wallner
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Emelie Olsson
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Richard J Squibb
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Ugne Miniotaite
- Department of Physics, Chalmers University of Technology, Kemigården 1, 412 96 Gothenburg, Sweden
| | - Emma Forsmalm
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Malin Forsmalm
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Stefano Stranges
- IOM-CNR Tasc, SS-14, Km 163.5 Area Science Park, Basovizza 34149, Trieste, Italy.,Dipartimento di Chimica e Tecnologie del Farmaco, Universitá Sapienza, Rome I-00185, Italy
| | - John M Dyke
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
| | - Fernanda Duarte
- Department of Chemistry, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - John H D Eland
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK
| | - Raimund Feifel
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
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12
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Garner MH, Laplaza R, Corminboeuf C. Helical versus linear Jahn–Teller distortions in allene and spiropentadiene radical cations. Phys Chem Chem Phys 2022; 24:26134-26143. [DOI: 10.1039/d2cp03544h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The allene radical cation can be stabilized both by Jahn–Teller distortion of the bond lengths and by torsion of the end-groups.
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Affiliation(s)
- Marc H. Garner
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ruben Laplaza
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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13
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Hall MR, Moggach SA, Low PJ. Syntheses and Structures of trans-bis(Alkenylacetylide) Ruthenium Complexes. Chem Asian J 2021; 16:3385-3403. [PMID: 34468081 DOI: 10.1002/asia.202100850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 08/25/2021] [Indexed: 11/08/2022]
Abstract
A series of ruthenium alkenylacetylide complexes trans-[Ru{C≡CC(=CH2 )R}Cl(dppe)2 ] (R=Ph (1 a), c C4 H3 S (1 b), 4-MeS-C6 H4 (1 c), 3,3-dimethyl-2,3-dihydrobenzo[b]thiophene (DMBT) (1 d)) or trans-[Ru{C≡C-c C6 H9 }Cl(dppe)2 ] (1 e) were allowed to react with the corresponding propargylic alcohol HC≡CC(Me)R(OH) (R=Ph (A), c C4 H3 S (B), 4-MeS-C6 H4 (C), DMBT (D) or HC≡C-c C6 H10 (OH) (E) in the presence of TlBF4 and DBU to presumably give alkenylacetylide/allenylidene intermediates trans-[Ru{C≡CC(=CH2 )R}{C=C=C(Me)}(dppe)2 ]PF6 ([2]PF6 ). These complexes were not isolated but deprotonated to give the isolable bis(alkenylacetylide) complexes trans-[Ru{C≡CC(=CH2 )R}2 (dppe)2 ] (R=Ph (3 a), c C4 H3 S (3 b), 4-MeS-C6 H4 (3 c), DMBT (3 d)) and trans-[Ru{C≡C-c C6 H9 }2 (dppe)2 ] (3 e). Analogous reactions of trans-[Ru(CH3 )2 (dmpe)2 ], featuring the more electron-donating 1,2-bis(dimethylphosphino)ethane (dmpe) ancillary ligands, with the propargylic alcohols A or C and NH4 PF6 in methanol allowed isolation of the intermediate mixed alkenylacetylide/allenylidene complexes trans-[Ru{C≡CC(=CH2 )R}{C=C=C(Me)}(dmpe)2 ]PF6 (R=Ph ([4 a]PF6 ), 4-MeS-C6 H4 ([4 c]PF6 ). Deprotonation of [4 a]PF6 or [4 c]PF6 gave the symmetric bis(alkenylacetylide) complexes trans-[Ru{C≡CC(=CH2 )R}2 (dmpe)2 ] (R=Ph (5 a), 4-MeS-C6 H4 (5 c)), the first of their kind containing the dmpe ancillary ligand sphere. Attempts to isolate bis(allenylidene) complexes [Ru{C=C=C(Me)R}2 (PP)2 ]2+ (PP=dppe, dmpe) from treatment of the bis(alkenylacetylide) species 3 or 5 with HBF4 ⋅ Et2 O were ultimately unsuccessful.
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Affiliation(s)
- Michael R Hall
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Stephen A Moggach
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
| | - Paul J Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley, 6009, Western Australia, Australia
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14
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Sitha S. Tetrel bonding in the realm of transition states favors silicon over Carbon: Role of water as a tetrel spectator in the formation of silaformamide. COMPUT THEOR CHEM 2021. [DOI: 10.1016/j.comptc.2021.113456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Bro-Jørgensen W, Garner MH, Solomon GC. Quantification of the Helicality of Helical Molecular Orbitals. J Phys Chem A 2021; 125:8107-8115. [PMID: 34491758 PMCID: PMC8450904 DOI: 10.1021/acs.jpca.1c05799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The frontier molecular orbital (MO) topology of linear carbon molecules, such as polyynes, can be visually identified as helices. However, there is no clear way to quantify the helical curvature of these π-MOs, and it is thus challenging to quantify correlations between the helical curvature and molecular properties. In this paper, we develop a method that enables us to compute the helical curvature of MOs based on their nodal planes. Using this method, we define a robust way of quantifying the helical nature of MOs (helicality) by their deviation from a perfect helix. We explore several limiting cases, including polyynes, metallacumulenes, cyclic allenes, and spiroconjugated systems, where the change in helical curvature is subtle yet clearly highlighted with this method. For example, we show that strain only has a minor effect on the helicality of the frontier orbitals of cycloallenes and that the MOs of spiroconjugated systems are close to perfect helices around the spiro-carbon. Our work provides a well-defined method for assessing orbital helicality beyond visual inspection of MO isosurfaces, thus paving the way for future studies of how the helicality of π-MOs affects molecular properties.
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Affiliation(s)
- William Bro-Jørgensen
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Marc H Garner
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Gemma C Solomon
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
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16
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Abstract
The new isonitrile-μ-carbido complexes [WPt(μ-C)Br(CNR)(PPh3)(CO)2(Tp*)] (R = C6H2Me3-2,4,6, C6H3Me2-2,6; Tp* = hydrotris(dimethylpyrazolyl)borate) rearrange irreversibly in polar solvents to provide the first examples of iminoketenylidene (CCNR) complexes.
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Affiliation(s)
- Liam K Burt
- Research School of Chemistry, Australian National University, Canberra, Australian Capital Territory, ACT 2601, Australia.
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17
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Baronas P, Komskis R, Tankelevičiu Tė E, Adomėnas P, Adomėnienė O, Juršėnas S. Helical Molecular Orbitals to Induce Spin-Orbit Coupling in Oligoyne-Bridged Bifluorenes. J Phys Chem Lett 2021; 12:6827-6833. [PMID: 34270894 DOI: 10.1021/acs.jpclett.1c01569] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Singlet-Triplet energy exchange is an area of active research due to its role in optoelectronic devices and photodynamic therapy. Large spin-orbit coupling (SOC) is difficult to achieve in simple hydrocarbon structures limiting the intersystem crossing (ISC) rates. A new approach to enhance the spin-orbit coupling via helical molecular orbitals is investigated in oligoyne-bridged bifluorenes. Transient absorption studies showed a singlet-to-triplet ISC rate of up to 6 ns-1 resulting in 0.84 triplet yield. Density functional calculations revealed a direct relation between high ISC and large SOC values mediated by helical molecular orbitals. Calculations and spectroscopic data also suggested that El-Sayed forbidden ISC occurs as a direct transition between 1ππ* and 3ππ*, which becomes allowed due to a symmetry-breaking interaction leading to mixing between orthogonal π-systems in the oligoyne fragment.
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Affiliation(s)
- P Baronas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania
| | - R Komskis
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania
| | - E Tankelevičiu Tė
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania
| | - P Adomėnas
- Fine Synthesis, Ltd., Kalvarijų g. 201E, LT-08311 Vilnius, Lithuania
| | - O Adomėnienė
- Fine Synthesis, Ltd., Kalvarijų g. 201E, LT-08311 Vilnius, Lithuania
| | - S Juršėnas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania
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18
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Sarbadhikary P, Misra A. Magnetic Modulation in Heteroallene and Heterocumulene Based tert-butyl Nitroxide Diradicals: Spin Delocalization and Conformation Play Crucial Roles. Chemphyschem 2021; 22:1379-1388. [PMID: 33977620 DOI: 10.1002/cphc.202100161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 04/27/2021] [Indexed: 11/11/2022]
Abstract
We have theoretically investigated the magnetic properties of heteroallene (>C=C=X-) and heterocumulene (>C=C=C=X-) based tert-butyl nitroxide diradicals (X is P/As). Calculation of magnetic exchange coupling constant (J) shows ferromagnetic interaction in heteroallene based diradicals. Whereas, in heterocumulene based diradicals, tuning of J value from antiferro- to ferro-magnetic state is observed from Z- to E- isomer. Delocalization of spin density from radical site to the coupler (in planar arrangement) is observed in spin distribution analysis which is also advocated by molecular orbital analysis. The typical feature of tert-butyl nitroxide radical creates spin delocalization along with spin polarization within the coupler. The J values of all the diradicals strongly depend on the dihedral angle between radical center and coupler. Magneto-structural correlation shows that the change in dihedral angle tunes the magnetic property for both the Z- and E- isomers of heterocumulenes depending on the spin accumulation on two nearby magnetic centers. The extent of spin delocalization and conformation of spin centers on the molecular axis are important for the different J values observed in our designed systems.
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Affiliation(s)
| | - Anirban Misra
- Department of Chemistry, University of North Bengal, Dist-Darjeeling, 734013, India
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19
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Ramirez M, Svatunek D, Liu F, Garg NK, Houk KN. Origins of
Endo
Selectivity in Diels–Alder Reactions of Cyclic Allene Dienophiles. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Melissa Ramirez
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095 USA
| | - Dennis Svatunek
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095 USA
| | - Fang Liu
- College of Sciences Nanjing Agricultural University Nanjing 210095 China
| | - Neil K. Garg
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095 USA
| | - Kendall N. Houk
- Department of Chemistry and Biochemistry University of California, Los Angeles Los Angeles CA 90095 USA
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20
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Ramirez M, Svatunek D, Liu F, Garg NK, Houk KN. Origins of Endo Selectivity in Diels-Alder Reactions of Cyclic Allene Dienophiles. Angew Chem Int Ed Engl 2021; 60:14989-14997. [PMID: 33851504 DOI: 10.1002/anie.202101809] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/20/2021] [Indexed: 11/08/2022]
Abstract
Strained cyclic allenes, first discovered in 1966 by Wittig and co-workers, have recently emerged as valuable synthetic building blocks. Previous experimental investigations, and computations reported here, demonstrate that the Diels-Alder reactions of furans and pyrroles with 1,2-cyclohexadiene and oxa- and azaheterocyclic analogs proceed with endo selectivity. This endo selectivity gives the adduct with the allylic saturated carbon of the cyclic allene endo to the diene carbons. The selectivity is very general and useful in synthetic applications. Our computational study establishes the origins of this endo selectivity. We analyze the helical frontier molecular orbitals of strained cyclic allenes and show how secondary orbital and electrostatic effects influence stereoselectivity. The LUMO of carbon-3 of the allene (C-3 is not involved in primary orbital interactions) interacts in a stabilizing fashion with the HOMO of the diene in such a way that the carbon of the cyclic allene attached to C-1 favors the endo position in the transition state. The furan LUMO, allene HOMO interaction reinforces this preference. These mechanistic studies are expected to prompt the further use of long-avoided strained cyclic allenes in chemical synthesis.
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Affiliation(s)
- Melissa Ramirez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Dennis Svatunek
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Fang Liu
- College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China
| | - Neil K Garg
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Kendall N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
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21
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Garner MH, Corminboeuf C. Helical electronic transitions of spiroconjugated molecules. Chem Commun (Camb) 2021; 57:6408-6411. [DOI: 10.1039/d1cc01904j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The π–π* transitions of disubstituted spiropentadiene become helical due to mixing of its two perpendicular π-systems. The helicity is symmetry-protected and gives rise to experimentally observable effects, such as optical activity.
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Affiliation(s)
- Marc H. Garner
- Laboratory for Computational Molecular Design
- Institute of Chemical Sciences and Engineering
- Ecole Polytechnique Federale de Lausanne (EPFL)
- Lausanne 1015
- Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design
- Institute of Chemical Sciences and Engineering
- Ecole Polytechnique Federale de Lausanne (EPFL)
- Lausanne 1015
- Switzerland
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22
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Abstract
We introduce new and robust decompositions of mean-field Hartree-Fock and Kohn-Sham density functional theory relying on the use of localized molecular orbitals and physically sound charge population protocols. The new lossless property decompositions, which allow for partitioning one-electron reduced density matrices into either bond-wise or atomic contributions, are compared to alternatives from the literature with regard to both molecular energies and dipole moments. Besides commenting on possible applications as an interpretative tool in the rationalization of certain electronic phenomena, we demonstrate how decomposed mean-field theory makes it possible to expose and amplify compositional features in the context of machine-learned quantum chemistry. This is made possible by improving upon the granularity of the underlying data. On the basis of our preliminary proof-of-concept results, we conjecture that many of the structure-property inferences in existence today may be further refined by efficiently leveraging an increase in dataset complexity and richness.
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Affiliation(s)
- Janus J Eriksen
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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23
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Pinter P, Munz D. Controlling Möbius-Type Helicity and the Excited-State Properties of Cumulenes with Carbenes. J Phys Chem A 2020; 124:10100-10110. [DOI: 10.1021/acs.jpca.0c07940] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Piermaria Pinter
- Department of Chemistry and Pharmacy, General and Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
| | - Dominik Munz
- Inorganic Chemistry: Coordination Chemistry, Saarland University, Campus Geb. C4.1, 66123 Saarbrücken, Germany
- Department of Chemistry and Pharmacy, General and Inorganic Chemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058 Erlangen, Germany
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24
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Karadakov PB, Di M, Cooper DL. Excited-State Aromaticity Reversals in Möbius Annulenes. J Phys Chem A 2020; 124:9611-9616. [PMID: 33155798 DOI: 10.1021/acs.jpca.0c08594] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
It is suggested that Möbius annulenes follow a rule similar to Baird's rule such that the 4n and 4n + 2 criteria for Möbius electronic ground-state aromaticity and antiaromaticity are reversed in the lowest triplet and first singlet excited electronic states. Support comes from an investigation of aromaticity in the ground (S0), lowest triplet (T1), and first singlet excited (S1) electronic states of the Möbius-aromatic cyclononatetraenyl cation, C9H9+, using isotropic magnetic shielding isosurfaces calculated with state-optimized complete-active-space self-consistent field wave functions constructed from gauge-including atomic orbitals. Examination of these isosurfaces demonstrates that while the S0 state of C9H9+ is aromatic, the T1 and S1 states are antiaromatic.
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Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - Make Di
- Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K
| | - David L Cooper
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K
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25
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Garner MH, Corminboeuf C. Correlation between Optical Activity and the Helical Molecular Orbitals of Allene and Cumulenes. Org Lett 2020; 22:8028-8033. [DOI: 10.1021/acs.orglett.0c02980] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Marc H. Garner
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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26
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Gunasekaran S, Venkataraman L. Tight-binding analysis of helical states in carbyne. J Chem Phys 2020; 153:124304. [DOI: 10.1063/5.0021146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Suman Gunasekaran
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Latha Venkataraman
- Department of Chemistry, Columbia University, New York, New York 10027, USA
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
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27
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Hall MR, Korb M, Moggach SA, Low PJ. Further Chemistry of Ruthenium Alkenyl Acetylide Complexes: Routes to Allenylidene Complexes via a Series of Electrophilic Addition Reactions. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00371] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael R. Hall
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Marcus Korb
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Stephen A. Moggach
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
| | - Paul J. Low
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia
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28
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Hoffmann R, Malrieu JP. Simulation vs. Understanding: A Tension, in Quantum Chemistry and Beyond. Part B. The March of Simulation, for Better or Worse. Angew Chem Int Ed Engl 2020; 59:13156-13178. [PMID: 31675462 DOI: 10.1002/anie.201910283] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Indexed: 11/08/2022]
Abstract
In the second part of this Essay, we leave philosophy, and begin by describing Roald's being trashed by simulation. This leads us to a general sketch of artificial intelligence (AI), Searle's Chinese room, and Strevens' account of what a go-playing program knows. Back to our terrain-we ask "Quantum Chemistry, † ca. 2020?" Then we move to examples of Big Data, machine learning and neural networks in action, first in chemistry and then affecting social matters, trivial to scary. We argue that moral decisions are hardly to be left to a computer. And that posited causes, even if recognized as provisional, represent a much deeper level of understanding than correlations. At this point, we try to pull the reader up, giving voice to the opposing view of an optimistic, limitless future. But we don't do justice to that view-how could we, older mammals on the way to extinction that we are? We try. But then we return to fuss, questioning the ascetic dimension of scientists, their romance with black boxes. And argue for a science of many tongues.
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Affiliation(s)
- Roald Hoffmann
- Dept. of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14850, USA
| | - Jean-Paul Malrieu
- Laboratoire de Chimie et Physique Quantiques, Université de Toulouse 3, 118 route de Narbonne, 31062, Toulouse, France
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29
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Hoffmann R, Malrieu J. Simulation vs. Understanding: A Tension, in Quantum Chemistry and Beyond. Part B. The March of Simulation, for Better or Worse. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201910283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Roald Hoffmann
- Dept. of Chemistry and Chemical Biology Cornell University Ithaca NY 14850 USA
| | - Jean‐Paul Malrieu
- Laboratoire de Chimie et Physique Quantiques Université de Toulouse 3 118 route de Narbonne 31062 Toulouse France
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30
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Hall MR, Steen RR, Korb M, Sobolev AN, Moggach SA, Lynam JM, Low PJ. Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water. Chemistry 2020; 26:7226-7234. [DOI: 10.1002/chem.201905399] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/01/2020] [Indexed: 12/27/2022]
Affiliation(s)
- Michael R. Hall
- School of Molecular SciencesUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
| | - Rachel R. Steen
- Department of ChemistryUniversity of York Heslington York YO10 5DG UK
| | - Marcus Korb
- School of Molecular SciencesUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
| | - Alexandre N. Sobolev
- School of Molecular SciencesUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
| | - Stephen A. Moggach
- School of Molecular SciencesUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
- Centre for Microscopy, Characterisation and AnalysisUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
| | - Jason M. Lynam
- Department of ChemistryUniversity of York Heslington York YO10 5DG UK
| | - Paul J. Low
- School of Molecular SciencesUniversity of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
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31
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Li P, Yang Z, Zhang Z, Pu L, King RB. Understanding the singlet–triplet energy splittings in transition metal-capped carbon chains. Phys Chem Chem Phys 2020; 22:2858-2869. [DOI: 10.1039/c9cp06591a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Density functional theory and molecular orbital analysis suggest that the odd–even alternation of singlet–triplet energy separations is a general feature of transition metal-capped carbon chains, determined primarily by the carbon chains.
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Affiliation(s)
- Peizhi Li
- College of Chemistry & Pharmacy
- Northwest A&F University
- Yangling
- P. R. China
| | - Zhipeng Yang
- College of Chemistry & Pharmacy
- Northwest A&F University
- Yangling
- P. R. China
| | - Zhong Zhang
- College of Chemistry & Pharmacy
- Northwest A&F University
- Yangling
- P. R. China
| | - Liang Pu
- College of Chemistry & Pharmacy
- Northwest A&F University
- Yangling
- P. R. China
| | - R. Bruce King
- Department of Chemistry and Center for Computational Chemistry
- University of Georgia
- Athens
- USA
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32
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Zhang C, Turyanska L, Cao H, Zhao L, Fay MW, Temperton R, O'Shea J, Thomas NR, Wang K, Luan W, Patanè A. Hybrid light emitting diodes based on stable, high brightness all-inorganic CsPbI 3 perovskite nanocrystals and InGaN. NANOSCALE 2019; 11:13450-13457. [PMID: 31287481 DOI: 10.1039/c9nr03707a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Despite important advances in the synthesis of inorganic perovskite nanocrystals (NCs), the long-term instability and degradation of their quantum yield (QY) over time need to be addressed to enable the further development and exploitation of these nanomaterials. Here we report stable CsPbI3 perovskite NCs and their use in hybrid light emitting diodes (LEDs), which combine in one system the NCs and a blue GaN-based LED. Nanocrystals with improved morphological and optical properties are obtained by optimizing the post-synthesis replacement of oleic acid ligands with iminodibenzoic acid: the NCs have a long shelf-life (>2 months), stability under different environmental conditions, and a high QY, of up to 90%, in the visible spectral range. Ligand replacement enables the engineering of the morphological and optical properties of the NCs. Furthermore, the NCs can be used to coat the surface of a GaN-LED to realize a stable diode where they are excited by blue light from the LED under low current injection conditions, resulting in emissions at distinct wavelengths in the visible range. The high QY and fluorescence lifetime in the nanosecond range are key parameters for visible light communication, an emerging technology that requires high-performance visible light sources for secure, fast energy-efficient wireless transmission.
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Affiliation(s)
- Chengxi Zhang
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK. and East China University of Science and Technology, Shanghai 200237, China
| | - Lyudmila Turyanska
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK. and School of Chemistry, University of Lincoln, Lincoln LN6 7TS, UK
| | - Haicheng Cao
- Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Lixia Zhao
- Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Michael W Fay
- Nanoscale and Microscale Research Centre, University of Nottingham, NG7 2RD, UK
| | - Robert Temperton
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK.
| | - James O'Shea
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK.
| | - Neil R Thomas
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK
| | - Kaiyou Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Weiling Luan
- East China University of Science and Technology, Shanghai 200237, China
| | - Amalia Patanè
- School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK.
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33
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Carlotti M, Soni S, Qiu X, Sauter E, Zharnikov M, Chiechi RC. Systematic experimental study of quantum interference effects in anthraquinoid molecular wires. NANOSCALE ADVANCES 2019; 1:2018-2028. [PMID: 31304460 PMCID: PMC6592160 DOI: 10.1039/c8na00223a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/07/2019] [Indexed: 05/17/2023]
Abstract
In order to translate molecular properties in molecular-electronic devices, it is necessary to create design principles that can be used to achieve better structure-function control oriented toward device fabrication. In molecular tunneling junctions, cross-conjugation tends to give rise to destructive quantum interference effects that can be tuned by changing the electronic properties of the molecules. We performed a systematic study of the tunneling charge-transport properties of a series of compounds characterized by an identical cross-conjugated anthraquinoid molecular skeleton but bearing different substituents at the 9 and 10 positions that affect the energies and localization of their frontier orbitals. We compared the experimental results across three different experimental platforms in both single-molecule and large-area junctions and found a general agreement. Combined with theoretical models, these results separate the intrinsic properties of the molecules from platform-specific effects. This work is a step towards explicit synthetic control over tunneling charge transport targeted at specific functionality in (proto-)devices.
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Affiliation(s)
- Marco Carlotti
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Saurabh Soni
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Xinkai Qiu
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Eric Sauter
- Applied Physical Chemistry , Heidelberg University , Im Neuenheier Feld 253 , Heidelberg 69120 , Germany
| | - Michael Zharnikov
- Applied Physical Chemistry , Heidelberg University , Im Neuenheier Feld 253 , Heidelberg 69120 , Germany
| | - Ryan C Chiechi
- Zernike Institute for Advanced Materials , Nijenborgh 4 , 9747 AG Groningen , The Netherlands .
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
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Garner MH, Jensen A, Hyllested LOH, Solomon GC. Helical orbitals and circular currents in linear carbon wires. Chem Sci 2019; 10:4598-4608. [PMID: 31123570 PMCID: PMC6496982 DOI: 10.1039/c8sc05464a] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 03/14/2019] [Indexed: 01/07/2023] Open
Abstract
Disubstituted odd-carbon cumulenes are linear carbon wires with helical π-orbitals, which results in circular current around the wire.
Disubstituted odd-carbon cumulenes are linear carbon wires with near-degenerate helical π-orbitals. Such cumulenes are chiral molecules but their electronic structure consists of helical orbitals of both chiralities. For these helical molecular orbitals to give rise to experimentally observable effects, the near-degenerate orbitals of opposite helicities must be split. Here we show how pyramidalized single-faced π-donors, such as the amine substituent, provide a strategy for splitting the helical molecular orbitals. The chirality induced by the amine substituents allow for systematic control of the helicity of the frontier orbitals. We examine how the helical orbitals in odd-carbon cumulenes control the coherent electron transport properties, and we explicitly predict two modes in the experimental single-molecule conductance for these molecules. We also show that the current density through these linear wires exhibits strong circular currents. The direction of the circular currents is systematically controlled by the helicity of the frontier molecular orbitals, and is therefore altered by changing between the conformations of the molecule. Furthermore, the circular currents are subject to a full ring-reversal around antiresonances in the Landauer transmission, emphasizing the relation to destructive quantum interference. With circular currents present around truly linear carbon wires, cumulenes are promising candidates for novel applications in molecular electronics.
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Affiliation(s)
- Marc H Garner
- Department of Chemistry , Nano-Science Center , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen Ø , Denmark . ;
| | - Anders Jensen
- Department of Chemistry , Nano-Science Center , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen Ø , Denmark . ;
| | - Louise O H Hyllested
- Department of Chemistry , Nano-Science Center , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen Ø , Denmark . ;
| | - Gemma C Solomon
- Department of Chemistry , Nano-Science Center , University of Copenhagen , Universitetsparken 5 , DK-2100 , Copenhagen Ø , Denmark . ;
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Karadakov PB, Cooper DL. Does the Electronic Structure of Möbius Annulenes Follow Heilbronner's Ideas? Chemphyschem 2018; 19:3186-3190. [PMID: 30311726 DOI: 10.1002/cphc.201800884] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Indexed: 11/11/2022]
Abstract
It is shown, on the example of the monocyclic cyclononatetraenyl cation,C 9 H 9 + , that the fully-variational optimization of modern ab initio wavefunctions based on spin-coupled generalized valence bond (SCGVB) theory vindicates, in a surprising level of detail, essential features of Heilbronner's ideas for the electronic structure of Möbius annulenes such as the arrangement of overlapping carbon 2p atomic orbitals along a Möbius strip, leading to a phase inversion between the first and last orbitals. In the SCGVB description, the aromaticity of this Möbius system with eight π electrons follows from the extensive resonance between VB structures.
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Affiliation(s)
- Peter B Karadakov
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
| | - David L Cooper
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UK
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Greenfield JL, Evans EW, Di Nuzzo D, Di Antonio M, Friend RH, Nitschke JR. Unraveling Mechanisms of Chiral Induction in Double-Helical Metallopolymers. J Am Chem Soc 2018; 140:10344-10353. [PMID: 30024156 PMCID: PMC6114842 DOI: 10.1021/jacs.8b06195] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Indexed: 12/18/2022]
Abstract
Self-assembled helical polymers hold great promise as new functional materials, where helical handedness controls useful properties such as circularly polarized light emission or electron spin. The technique of subcomponent self-assembly can generate helical polymers from readily prepared monomers. Here we present three distinct strategies for chiral induction in double-helical metallopolymers prepared via subcomponent self-assembly: (1) employing an enantiopure monomer, (2) polymerization in a chiral solvent, (3) using an enantiopure initiating group. Kinetic and thermodynamic models were developed to describe the polymer growth mechanisms and quantify the strength of chiral induction, respectively. We found the degree of chiral induction to vary as a function of polymer length. Ordered, rod-like aggregates more than 70 nm long were also observed in the solid state. Our findings provide a basis to choose the most suitable method of chiral induction based on length, regiochemical, and stereochemical requirements, allowing stereochemical control to be established in easily accessible ways.
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Affiliation(s)
- Jake L. Greenfield
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United
Kingdom
| | - Emrys W. Evans
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - Daniele Di Nuzzo
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - Marco Di Antonio
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United
Kingdom
| | - Richard H. Friend
- Cavendish
Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - Jonathan R. Nitschke
- Department
of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United
Kingdom
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Aoki Y, Orimoto Y, Imamura A. One-Handed Helical Orbitals in Conjugated Molecules. ACS CENTRAL SCIENCE 2018; 4:664-665. [PMID: 29974060 PMCID: PMC6026773 DOI: 10.1021/acscentsci.8b00228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Affiliation(s)
- Yuriko Aoki
- Department of Material
Sciences, Faculty of Engineering Sciences, Kyushu University, 6-1
Kasuga-Park, Fukuoka 816-8580, Japan
| | - Yuuichi Orimoto
- Department of Material
Sciences, Faculty of Engineering Sciences, Kyushu University, 6-1
Kasuga-Park, Fukuoka 816-8580, Japan
| | - Akira Imamura
- Hiroshima Kokusai Gakuin University, Nakano 6-20-1, Aki-ward, Hiroshima 739-0321, Japan
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