T. Hoshiba, T. Ida, M. Mizuno
Jan 9, 2002
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0
Influential Citations
4
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract An unsymmetrical fluoran dye, 3-diethylamino-6-methyl-7-chlorofluoran (DEAMCF) is one of the leuco dyes which shows the coloring-to-decoloring reversible reaction with acidity. We calculated the 13C chemical shieldings of the DEAMCF with the frame model compounds using ab initio gauge invariant atomic orbital methods, and compared it with the experimental shifts. The calculated values of the frame compounds are in good agreement with the experimental ones in the error range of −4.9–16.7 ppm. The calculated ones for the decolored-form of the DEAMCF reflected the observed ones, although the errors range from −13.4 to 23.1 ppm. Furthermore, we analyzed the UV–Visible absorption spectra of the decolored and colored forms of DEAMCF by a semiempirical ZINDO MO method. For the colored form, the observed absorption peaks at 550 and 510 nm correspond to the excitation from π-bonding HOMO (π-electrons which conjugated in xanthene ring) and π-bonding nearest HOMO (π-electrons concentrated in benzene-ring with methyl and Cl groups of xanthene) to π∗-antibonding LUMO (π∗-electrons of xanthene), respectively.