Cyclization Reaction Dynamics of a Photochromic Diarylethene Derivative as Revealed by Femtosecond to Microsecond Time-Resolved Spectroscopy

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• 作者：Yukihide Ishibashi ; Mika Fujiwara ; Toshiyuki Umesato ; Hisayuki Saito ; Seiya Kobatake ; Masahiro Irie ; Hiroshi Miyasaka
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 17, 2011
• 年：2011
• 卷：115
• 期：10
• 页码：4265-4272
• 全文大小：999K
• 年卷期：v.115,no.10(March 17, 2011)
• ISSN：1932-7455

文摘

Cyclization reaction of a photochromic diarylethene derivative, 1,2-bis(2-methyl-3-benzothienyl)perfluorocyclopentene (BT), in nonpolar alkane solutions with different viscosity was investigated by means of femtosecond鈭抦icrosecond transient absorption spectroscopy and a time-correlated single-photon counting method. Transient absorption measurements revealed that a ring closure rapidly occurred with a time constant of 450 fs. In addition to this rapid cyclization, transient species with longer lifetimes (ca. 150 ps and ca. 1 渭s) were observed. The faster time constant of 150 ps was independent of the solvent viscosity and was assigned to the fluorescence lifetime of a conformer with molecular geometry unfavorable for the ring closure. The longer component was strongly quenched in the solution purged with O₂ and was attributed to the triplet state of the open-ring form. Steady-state measurement and nanosecond transient absorption spectroscopy revealed that the cyclization process did not occur via the triplet state of BT. These results indicate that only the rapid reaction taking place in subpicosecond time region was responsible for the cyclization process. The key factors regulating the cyclization reaction of diarylethene derivatives were discussed on the basis of the solvent viscosity dependence, by comparing the present results with those obtained for other diarylethene derivatives.