Time-dependent density functional theory study on electronically excited States of coumarin 102 chromophore in aniline solvent: reconsideration of the electronic excited-state hydrogen-bonding dynamics.
The time-dependent density functional theory method was performed to investigate the electronically excited states of the hydrogen-bonded complex formed by coumarin 102 (C102) chromophore and the hydrogen-donating aniline solvent. At the same time, the electronic excited-state hydrogen-bonding dynamics for the photoexcited C102 chromophore in solution was also reconsidered. We demonstrated that the intermolecular hydrogen bond CO...H-N between C102 and aniline molecules is significantly strengthened in the electronically excited-state upon photoexcitation, since the calculated hydrogen bond energy increases from 25.96 kJ/mol in the ground state to 37.27 kJ/mol in the electronically excited state. Furthermore, the infrared spectra of the hydrogen-bonded C102-aniline complex in both the ground state and the electronically excited state were also calculated. The hydrogen bond strengthening in the electronically excited-state was confirmed for the first time by monitoring the spectral shift of the stretching vibrational mode of the hydrogen-bonded N-H group in different electronic states. Therefore, we believed that the dispute about the intermolecular hydrogen bond cleavage or strengthening in the electronically excited-state of coumarin 102 chromophore in hydrogen donating solvents has been clarified by our studies.
Henan Normal University, Xinxiang 453007, China. yf-liu@henannu.edu.cn
Yufang
Y
Liu
Junxia
J
Ding
Deheng
D
Shi
Jinfeng
J
Sun
D000814:Aniline Compounds / Q000737:chemistry*; D003374:Coumarins / Q000737:chemistry*; D004583:Electrons; D006860:Hydrogen Bonding; D008956:Models, Chemical; D012997:Solvents; D017550:Spectroscopy, Fourier Transform Infrared; D013995:Time
D000814:Aniline Compounds; D003374:Coumarins; D012997:Solvents; C030123:coumarin; C023650:aniline