Femtosecond Laser Photolysis Studies on Temperature Dependence of Cyclization and Cycloreversion Reactions of a Photochromic Diarylethene Derivative

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• 作者：Yukihide Ishibashi ; Toshiyuki Umesato ; Seiya Kobatake ; Masahiro Irie ; Hiroshi Miyasaka
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：February 23, 2012
• 年：2012
• 卷：116
• 期：7
• 页码：4862-4869
• 全文大小：420K
• 年卷期：v.116,no.7(February 23, 2012)
• ISSN：1932-7455

文摘

Temperature dependencies of cyclization and cycloreversion processes of a photochromic diarylethene derivative, 1,2-bis(2-methyl-3-benzothienyl)perfluorocyclopentene (BT), were investigated by steady-state spectroscopy and femtosecond laser photolysis methods. Steady-state measurements revealed that the cyclization reaction quantum yield and the fraction of the conformer with C_2v symmetry favorable for the cyclization (antiparallel, AP conformer) were independent of temperature in the range of 253鈥?43 K. These results indicated that the cyclization reaction of the AP conformer in the open-ring isomer in the excited state had no apparent temperature dependence and suggested that the fate of the excited AP conformer in the open-ring isomer, such as cyclization or deactivation to the ground state, was determined at the conical intersection. On the other hand, the cycloreversion reaction was dependent on the temperature; the reaction quantum yield increased together with a decrease in the lifetime of the excited state of the closed-ring isomer with increasing temperature. On the basis of the adiabatic energy surface for the reaction profiles, it was deduced that the rapid deactivation into the ground state took place in the S₁ state in competition with the activated pathways leading to the conical intersection where the cycloreversion occurred.