Highly Stable Supramolecular Donor–Acceptor Complexes Involving a Bis(18-Crown-6)azobenzene as Weak Donor: Structure–Property Relationships

Ushakov, E.N.; Martyanov, T.P.; Vedernikov, A.I.; Efremova, A.A.; Moiseeva, A.A.; Kuz’mina, L.G.; Dmitrieva, S.N.; Howard, J.A.; Gromov, S.P.

Авторы: Ushakov E.N., Martyanov T.P., Vedernikov A.I., Efremova A.A., Moiseeva A.A., Kuz’mina L.G., Dmitrieva S.N., Howard J.A.K, Gromov S.P.
Журнал: ACS Omega
Том: 5
Номер: 40
Год издания: 2020
Первая страница: 25993
Последняя страница: 26004
DOI: 10.1021/acsomega.0c03441
Аннотация: The physicochemical properties of highly stablesupramolecular donor−acceptor (D−A) complexes of a bis(18-crown-6)azobenzene (weak π-donor) with a series of bis-(ammonioalkyl) derivatives of viologen-like molecules (π-acceptors) in acetonitrile were studied using cyclic voltammetry, UV−vis absorption spectroscopy, 1H NMR spectroscopy, and density functional theory (DFT) calculations. The crystalline structures ofthe bis(crown)azobenzene and its complex with a bis-(ammoniopropyl) derivative of 2,7-diazapyrene were determined by X-ray diffraction analysis. In solution, all of the supramolecular D−A complexes studied have a pseudocyclic structure owing toditopic coordination of the ammonium groups of the acceptor to the crown ether moieties of the donor. These complexes show somewhat lower stability as compared with the previously studied complexes of the related derivative of stilbene (strong π-donor), which is explained by the relatively weak intermolecular chargetransfer (CT) interactions. Time-dependent DFT calculations predict that the low-energy CT transition in the D−A complex of thebis(crown)azobenzene with a bis(ammoniopropyl) derivative of 4,4′-bipyridine lies between the local ππ* and nπ* transitions of the azobenzene. The absorption band associated with the CT transition is indiscernible in the spectrum since it is overlapped with broad and more intense ππ* and nπ* bands. It was found that the E → Z photoisomerization quantum yield of the bis(crown)azobenzene decreases by almost an order of magnitude upon the complexation with the 4,4′-bipyridine derivative. This effect was tentativelyattributed to the intermolecular electron transfer that occurs in the 1ππ* excited state of the azobenzene and competes with the 1ππ* → 1nπ* internal conversion.
Добавил в систему: Громов Сергей Пантелеймонович

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Highly Stable Supramolecular Donor–Acceptor Complexes Involving a Bis(18-Crown-6)azobenzene as Weak Donor: Structure–Property Relationshipsстатья Исследовательская статья

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