Unusual behavior in di-substituted piperidine and piperazine anthraquinones upon protonation - spectral, electrochemical, and quantum chemical studies
Anna Wcisło , Iwona Dąbkowska , Justyna Czupryniak , Tadeusz Ossowski , Dorota Zarzeczańska
AbstractThe objective of the study is to determine the influence of a substituent on the spectroscopic and electrochemical properties of a series of novel 9,10‑anthraquinone piperidine and piperazine derivatives.We conducted UV–Vis spectroscopy, pH-spectroscopic titration, and cyclic voltammetry measurements with an interesting phenomenon observed in the case of di-substituted quinones. Compounds with substituents in position 1 and 8 exhibit a significant increase in the absorption intensity of the monoprotonated form. Spectroscopic studies in the conjunction with time-dependent density functional theory (TD-DFT) calculations were employed to explore the unusual behavior. The state-of-the-art quantum chemistry calculations including bulk solvent in the polarizable continuum model (PCM) enabled the study of prototropic tautomerization and its influence on the position of absorption bands. The results of cyclic voltammetry measurements allowed us to determine the deciding factor influencing the reduction – the number of substituents and the possibility of the hydrogen bond formation of the charged states.
|Journal series||Journal of Molecular Liquids, ISSN 0167-7322, (A 30 pkt)|
|Publication size in sheets||0.5|
|Keywords in English||Spectroscopy, electrochemistry, intramolecular charge transfer, protolytic forms, TD-DFT, theoretical UV-Vis spectra|
|Score|| = 30.0, 01-02-2019, ArticleFromJournal|
= 30.0, 01-02-2019, ArticleFromJournal
|Publication indicators||: 2017 = 4.513 (2) - 2017=3.929 (5)|
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