Intermolecular hydrogen-bonding effects on photophysics and photochemistry

Abstract

Intermolecular hydrogen bonding, as an important site-specific interaction between hydrogen donor and acceptor molecules both in the gas phase and in solution, plays a significant role and has a remarkable influence on the photophysics and photochemistry of chromophores in the hydrogen-bonding surroundings. In recent years, the excited-state structures and dynamics of the intermolecular hydrogen bonding have been widely investigated by using both the experimental and theoretical methods. This review article focuses on the recent research progress of the important intermolecular hydrogen-bonding effects on the non-adiabatic photophysical processes and photochemical reactions. Firstly, the corresponding relationship between electronic spectral red-shift or blue-shift and excited-state intermolecular hydrogen bond strengthening or weakening has been clarified. A dynamic equilibrium induced by the intermolecular hydrogen bond strengthening in the electronically excited state of fluorenone chromophore was used to explain the steady-state spectral features. The stepwise mechanism of excited-state double proton transfer reaction for the 2-aminopyridine/acid systems was demonstrated. The role of intermolecular hydrogen bonding on the excited-state proton transfer in the sensing mechanism of fluorescent probes has also been discussed. Moreover, a dihydrogen-bonded complex formed by borane-trimethylamine and phenol showed interesting geometric structures and infared spectrum in electronically excited state.

Keywords:

• intermolecular hydrogen bonding
• photophysics and photochemistry
• fluorescence quenching
• spectral shifts
• excited-state double proton transfer
• fluorescent probes
• sensing mechanism
• dihydrogen bond

Acknowledgements

This work was financially supported by the Programme of Shenyang Key Laboratory of Optoelectronic materials and technology (Grant No. F12-254-1-00), the National Natural Science Foundation of China (Grant No. 11274149 and 21271095), the Natural Science Foundation of Liaoning Province of China (Grant No. 20111035, 201102080 and 20121032) and Liaoning Provincial Department of Education Project (Grant No. L20111003). We thank Drs. S. Chai, G.Y. Li, and Y.H. Liu for their works in this field.