Publication Date:
2016-02-02
Description:
So far, coumarin dyes have been extensively studied with various means to understand their photophysical behaviors and photochemical properties. Here, our performing time-dependent density functional theory calculation is aimed at exploring the excited-state hydrogen bonding dynamics of coumarin 153 (C153) in protic ethanol (EtOH) solvent. The calculated results suggest that the excited-state hydrogen bond C O⋯H O between C O group and O H group in the C153-EtOH complex is strengthened, and the S 0 S 1 transition of the complex corresponds to the highest occupied molecular orbital (HOMO) hopping to the lowest unoccupied molecular orbital (LUMO). The excited-state hydrogen bond strengthening has been further confirmed by its larger binding energy in the S 1 state than in the S 0 state. In addition, because of the formation of the hydrogen bond C O⋯H O, a red shift of about 7 nm occurs in the electronic spectra of the C153-EtOH complex, which is in good accordance with the experiment result. Copyright © 2016 John Wiley & Sons, Ltd. We theoretically investigate the property of the hydrogen bond of C153-EtOH complex in the aspects of the frontier molecular orbital, optimized structures, steady-state absorption and fluorescence spectra, and infrared vibrational spectra. The results suggest that the strengthening of C=O⋯H-O induces a redshift of 7 nm in UV-Vis absorption spectra and energy gap between HOMO and LUMO is deceased in C153-EtOH complex as well as the S1 state of C153-EtOH is a locally excited state.
Print ISSN:
0894-3230
Electronic ISSN:
1099-1395
Topics:
Chemistry and Pharmacology
,
Physics
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