A. Matwijczuk, D. Karcz, Katarzyna Pustuła
Sep 1, 2018
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0
Influential Citations
12
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Journal
Journal of Luminescence
Abstract
Abstract This work deals with the results of fluorescence studies of 4-(5-(methylamino-1,3,4-thiadiazol-2-yl))benzene-1,3-diol (MATB) and 4-(5-(methyl-1,3,4-thiadiazol-2-yl))benzene-1,3-diol (MTB) in an aqueous solution at various pH. The aqueous solutions of both compounds analysed exhibited interesting fluorescence effects: dual fluorescence for MTB and two clearly separated distinct (partially overlapping) fluorescence emissions for MATB. Such fluorescence effects were observed in the aqueous solutions at pH 1–7 for MTB and pH 1–5 for MATB. At higher pH values, single fluorescence emission band were observed for both compounds. Based on the results reported to date, it was concluded that the observed fluorescence effects were mainly influenced by aggregation factors (induced by concentration changes, conformational effects or other interactions, e.g. formation of hydrogen bonds) and charge transfer effects (pH-induced and structure (substituent)-dependent). The dual fluorescence effect was noted for the analysed MTB compound (which does not have the –NH– secondary amine group), whereas two distinctly separated fluorescence bands were observed for the MATB analogue (which has the secondary amine group). The results presented in this paper highlight the impact of the secondary amine moiety on the fluorescence effects observed a long the range of solvents tested. The experimental research is accompanied by density functional theory-based (DFT) molecular modelling, which provide some hypothesis of the microscopic origins of the phenomena observed.