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Wang H, Chen J, Duan C, Xu X, Zheng Y, Grabow JU, Gou Q, Caminati W. Switching Aromatic Character by Complexation: π to π* Change Seen in Molecular Rotation Spectra. J Phys Chem Lett 2021; 12:5150-5155. [PMID: 34032447 DOI: 10.1021/acs.jpclett.1c01318] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A dominating F···π*aromatic interaction is found to govern the benzaldehyde···tetrafluoromethane complex, as revealed by this rotational spectroscopic investigation. Secondary F···π*-C=O- and C σ*CF4···πaromatic interactions also contribute to the stability of the observed isomer. Narrow splittings have been observed in the rotational spectrum originating from a 3-fold internal rotation of CF4 above the aromatic moiety, and a corresponding V3 barrier was determined to be 1.572(14) kJ mol-1. This is the first rotational spectroscopic evidence in the literature implying that the aromatic π* antibonding orbital can be activated not only by electron-withdrawing substituents but also by complexation partners containing atoms with high electronegativity, like CF4. The results emphasize the partner molecules' role to modulate the π electron structure and show a change in the orbital character (π or π*) when participating in the formation of noncovalent interactions.
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Affiliation(s)
- Hao Wang
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Junhua Chen
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Chunguo Duan
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Xuefang Xu
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Yang Zheng
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Jens-Uwe Grabow
- Institut für Physikalische Chemie & Elektrochemie Leibniz, Universität Hannover, 30167 Hannover, Germany
| | - Qian Gou
- Department of Chemistry, School of Chemistry and Chemical Engineering, Chongqing University, Shapingba, Chongqing 401331, China
| | - Walther Caminati
- Dipartimento di Chimica "G. Ciamician", Università; di Bologna, I-40126 Bologna, Italy
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Domingos SR, Pérez C, Kreienborg NM, Merten C, Schnell M. Dynamic chiral self-recognition in aromatic dimers of styrene oxide revealed by rotational spectroscopy. Commun Chem 2021; 4:32. [PMID: 36697526 PMCID: PMC9814401 DOI: 10.1038/s42004-021-00468-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 02/01/2021] [Indexed: 01/28/2023] Open
Abstract
Chiral molecular recognition is a pivotal phenomenon in biomolecular science, governed by subtle balances of intermolecular forces that are difficult to quantify. Non-covalent interactions involving aromatic moieties are particularly important in this realm, as recurring motifs in biomolecular aggregation. In this work, we use high-resolution broadband rotational spectroscopy to probe the dynamic conformational landscape enclosing the self-pairing topologies of styrene oxide, a chiral aromatic system. We reach a definite assignment of four homochiral and two heterochiral dimers using auxiliary quantum chemistry calculations as well as structure-solving methods based on experimental isotopic information. A complete picture of the dimer conformational space is obtained, and plausible routes for conformational relaxation are derived. Molecular structures are discussed in terms of conformational flexibility, the concerted effort of weak intermolecular interactions, and their role in the expression of the molecular fit.
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Affiliation(s)
- Sérgio R. Domingos
- grid.7683.a0000 0004 0492 0453Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, Hamburg, 22607 Germany ,grid.8051.c0000 0000 9511 4342Present Address: CFisUC, Department of Physics, University of Coimbra, Coimbra, 3004-516 Portugal
| | - Cristóbal Pérez
- grid.7683.a0000 0004 0492 0453Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, Hamburg, 22607 Germany
| | - Nora M. Kreienborg
- grid.5570.70000 0004 0490 981XRuhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, Bochum, 44801 Germany
| | - Christian Merten
- grid.5570.70000 0004 0490 981XRuhr-Universität Bochum, Fakultät für Chemie und Biochemie, Organische Chemie II, Universitätsstraße 150, Bochum, 44801 Germany
| | - Melanie Schnell
- grid.7683.a0000 0004 0492 0453Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, Hamburg, 22607 Germany ,grid.9764.c0000 0001 2153 9986Institut für Physikalische Chemie, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, Kiel, 24118 Germany
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