Sotome Hikaru, Nagasaka Tatsuhiro, Une Kanako, Okui Chiaki, Ishibashi Yukihide, Kamada Kenji, Kobatake Seiya, Irie Masahiro, Miyasaka Hiroshi
Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University , Toyonaka, Osaka 560-8531, Japan.
Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University , Matsuyama, Ehime 790-8577, Japan.
J Phys Chem Lett. 2017 Jul 20;8(14):3272-3276. doi: 10.1021/acs.jpclett.7b01388. Epub 2017 Jul 6.
Off-resonant excitation of the closed-ring isomer of a photochromic diarylethene derivative at 730 nm induced the efficient cycloreversion reaction with a yield of ∼20%, while the reaction yield was only 2% under one-photon excitation at 365 nm. Excitation wavelength dependence of the one-photon cycloreversion reaction yield under steady-state irradiation in a wide wavelength range showed that the specific electronic state leading to the large cycloreversion reaction yield, which is originally forbidden in the optical transition but partially allowed owing to the low symmetry of the molecule, is spectrally overlapped with the electronic state accessible by the allowed one-photon optical transition in the UV region. Femtosecond transient absorption spectroscopy also revealed that the off-resonant two-photon excitation preferentially pumped the molecule into the specific state, leading to the 10-fold enhancement of the cycloreversion reaction.
在730 nm波长下对光致变色二芳基乙烯衍生物的闭环异构体进行非共振激发，可诱导高效的环化逆转反应，产率约为20%，而在365 nm波长下单光子激发时反应产率仅为2%。在宽波长范围内稳态辐照下，单光子环化逆转反应产率的激发波长依赖性表明，导致大环化逆转反应产率高的特定电子态，其在光学跃迁中原本是禁阻的，但由于分子的低对称性而部分允许，在光谱上与紫外区域允许的单光子光学跃迁可及的电子态重叠。飞秒瞬态吸收光谱还表明，非共振双光子激发优先将分子泵浦到特定状态，导致环化逆转反应增强10倍。
