Reconsideration on hydrogen bond strengthening or cleavage of photoexcited coumarin 102 in aqueous solvent: A DFT/TDDFT study

• Published in: Journal of computational chemistry Vol. 32; no. 14; pp. 3058 - 3061
• Main Authors: Miao, Chuang, Shi, Ying
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.11.2011; Wiley Subscription Services, Inc
• Subjects: Analytical chemistry; Coumarins - chemistry; electronic excited state; hydrogen bond cleavage; hydrogen bond strengthening; Hydrogen Bonding; Hydrogen bonds; Models, Molecular; Molecular chemistry; Molecules; Photochemical Processes; photoexcitation; Quantum Theory; Solutions; Solvents; Solvents - chemistry; Time Factors; Water - chemistry
• ISSN: 0192-8651; 1096-987X
• DOI: 10.1002/jcc.21888

In this work, the excited‐state hydrogen bonding dynamics of photoexcited coumarin 102 in aqueous solvent is reconsidered. The electronically excited states of the hydrogen bonded complexes formed by coumarin 102 (C102) chromophore and the hydrogen donating water solvent have been investigated using the time‐dependent density functional theory method. Two intermolecular hydrogen bonds between C102 and water molecules are considered. The previous works (Wells et al., J Phys Chem A 2008, 112, 2511) have proposed that one intermolecular hydrogen bond would be strengthened and the other one would be cleaved upon photoexcitation to the electronically excited states. However, our theoretical calculations have demonstrated that both the two intermolecular hydrogen bonds between C102 solute and H2O solvent molecules are significantly strengthened in electronically excited states by comparison with those in ground state. Hence, we have confirmed again that intermolecular hydrogen bonds between C102 chromophore and aqueous solvents are strengthened not cleaved upon electronic excitation, which is in accordance with Zhao's works. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011