Издательство СО РАН

Издательство СО РАН

Адрес Издательства СО РАН: Россия, 630090, а/я 187
Новосибирск, Морской пр., 2

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Яндекс.Метрика

Поиск по журналу

Журнал структурной химии

2015 год, номер 3

SUBSTITUENT EFFECTS ON THE ABSORPTION AND VIBRATIONAL SPECTRA OF SOME 2-HYDROXY SCHIFF BASES: DFT/TDDFT, NATURAL BOND ORBITAL AND EXPERIMENTAL STUDY

S.A. Elroby1,2, S. Aboud1, S.G. Aziz1, R. Hilal1,3
1King abdullaziz University, Jeddah, Saudi Arabia
rhilal@kau.edu.sa
2Benisuef University, Benisuef, Egypt
3Cairo University, Giza, Egypt
Ключевые слова: electronic spectra, vibrational spectra, DFT/TDDFT, solvent and substituent effects, NBO analysis, 2-hydroxy Schiff bases
Страницы: 444-457
Подраздел: ИССЛЕДОВАНИЕ СТРОЕНИЯ МОЛЕКУЛ ФИЗИЧЕСКИМИ МЕТОДАМИ

Аннотация

The electronic structure of salicylideneaniline (SA) and some of its derivatives are investigated both experimentally and theoretically. The equilibrium geometric structures of the studied compounds are determined at the B3LYP/6-311++G** level of theory. A set of 12 substituted SA derivatives is considered in the present work. The choice of these substituents aims to create a push-pull system on the SA basic structure which would shade light onto its photo physics. The electronic absorption spectra of SA are recorded in the UV-VIS region, in both polar and nonpolar solvents. Assignments of the observed electronic transitions are facilitated via time-dependent density functional theory (TDDFT) computations at the same level of theory. Electronic configurations contributing to each excited state are identified and the relevant MOs are characterized. The extent of delocalization and intramolecular charge transfer are estimated and discussed in terms of natural bond orbitals (NBO) analysis and second order perturbation interactions between donor and acceptor MOs. Solvent effects on the electronic absorption spectra are discussed in terms of the difference in polarizabilities of the ground and excited states. FTIR spectra of SA and its derivatives are measured in KBr platelets. Detailed vibrational assignments are given based on the calculated potential energy distributions. "IR marker bands" that characterize the SA framework are identified. The effect of substituents, the nature of the characteristic "marker bands", and intensity quenching of some bands are discussed.

DOI: 10.15372/JSC20150303