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PHOTOPHYSICAL PROPERTIES AND CONFORMATIONAL EQUILIBRIUM OF trans‐6‐STYRYLQUINOXALINE
Author(s) -
Kim Maeng Sup,
Shim Sang Chul
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb01978.x
Subject(s) - conformational isomerism , fluorescence , excited state , chemistry , polar , cndo/2 , photochemistry , wavelength , spectral line , materials science , molecule , physics , atomic physics , organic chemistry , optics , optoelectronics , astronomy
The wavelength dependent fluorescence spectra and bi‐exponential fluorescence decays of trans ‐6‐styrylquinoxaline (6‐StQx) indicate that two conformers exist in equilibrium in solution. When comparing the conformationally restricted analogues (5Me‐6‐StQx and 7Me‐6‐StQx) with 6‐StQx, the short‐wavelength absorbing conformer of 6‐StQx can be assigned to conformer(A) and the long‐wavelength absorbing component to conformer(B). The temperature effects on the fluorescence lifetime indicate that the short‐lived conformer(A) is the more stable conformer in non‐polar solvents, while the long‐lived conformer(B) is the stable component in polar solvents. The results of semiempir‐ical AMI and CNDO/S CI calculations on both the ground and excited states are consistent with the conclusions drawn from the spectral data.