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Ultrafast Photodissociation Dynamics of a Hexaarylbiimidazole Derivative with Pyrenyl Groups: Dispersive Reaction from Femtosecond to 10 ns Time Regions

2009; American Chemical Society; Volume: 131; Issue: 21 Linguagem: Inglês

10.1021/ja809195s

1943-2984

Hiroshi Miyasaka, Yusuke Satoh, Yukihide Ishibashi, Syoji Ito, Yutaka Nagasawa, Seiji Taniguchi, Haik Chosrowjan, Noboru Mataga, Daisuke Kato, Azusa Kikuchi, Jiro Abe,

Spectroscopy and Quantum Chemical Studies

The photodissociation dynamics of a hexaarylbiimidazole (HABI) derivative with two pyrenyl groups was investigated by time-resolved transient absorption spectroscopy and fluorescence measurements. Transient absorption spectroscopy revealed that photodissociation took place in the wide time region of <100 fs to 10 ns. On the other hand, fluorescence time profiles showed the dynamic red shift in the time region <100 ps. The apparent dispersive photodissociation process was attributed to the increase in the interaction between the pyrenyl moiety in the excited state and the other moiety in the ground state, resulting in the gradual increase of the activation energy for the crossing between the attractive potential surface of an excited pyrenyl unit and the repulsive potential surface.