Electronic structure, spectra and photophysical properties of N-triazinylderivatives of 1-aminopyrene. Semi-empirical theoretical study

The geometry and excited state characteristics of five N-triazinyl derivatives of 1-aminopyrene were calculated using AM1, CNDO/S and ZINDO/S methods. For the optimized structures of the studied molecules, Lb, La and Bb transitions (localized on the amino pyrene moiety) were found, as well as charge-transfer states characterized by a charge transfer from the amino pyrene to the triazinyl ring. The energy of such strongly polar charge-transfer states depends on the chemical structure of the compound and on the solvent polarity. The relationships among each charge-transfer-to-emitting state energy gap, solvent polarity and fluorescence quantum yield of the studied compounds are discussed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Excited state properties of N-triazinyl-1-aminopyrenes were calculated by CNDO/S. ► The transitions with a strong CT to MO localized on trizinyl ring were found. ► Their energy decreases with the electronegativity of the triazinyl ring. ► Their energy dramatically decreases also with solvent polarity (ZINDO). ► The energy gap between the CT and emitting state determines the qF.