Tsuboi Yasuyuki, Shimizu Ryosuke, Shoji Tatsuya, Kitamura Noboru
Department of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
J Am Chem Soc. 2009 Sep 9;131(35):12623-7. doi: 10.1021/ja9016655.
We demonstrate that a photochromic reaction can be driven by irradiation from a weak, near-infrared continuous-wave (NIR-CW) laser light. A two-photon ring-opening photochromic reaction of a diarylethene (DE) derivative can be induced by irradiation with a NIR-CW laser light (lambda = 808 nm). An ultrathin polymer film doped with DE in its closed form was coated onto a gold-nanoparticle-integrated glass substrate. Upon irradiation of the sample with a CW laser at low fluence (0.1-4.0 W/cm(2)), we could clearly observe bleaching of the DE (ring-opening reaction). Following the IR irradiation, the bleached absorption could be reversibly recovered by applying UV irradiation (ring-closing reaction). We verified that the yield of the photochromic ring-opening reaction of the DE was proportional to the square of the irradiation fluence. The origin of this NIR-CW-induced two-photon photochromic reaction is an "enhancing effect" that acts on the electromagnetic field (localized surface plasmon) of the gold nanoparticles. The DE interacts with the surface plasmon and receives energy from two photons, which excites it to a state from which the ring-opening reaction can be initiated.
我们证明，光致变色反应可由弱近红外连续波（NIR-CW）激光照射驱动。二芳基乙烯（DE）衍生物的双光子开环光致变色反应可由NIR-CW激光（波长 = 808 nm）照射诱导。将掺杂有封闭形式DE的超薄聚合物薄膜涂覆在集成了金纳米颗粒的玻璃基板上。用低通量（0.1 - 4.0 W/cm²）的连续波激光照射样品时，我们可以清楚地观察到DE的褪色（开环反应）。红外照射后，通过施加紫外照射（闭环反应），漂白后的吸收可以可逆地恢复。我们验证了DE光致变色开环反应的产率与照射通量的平方成正比。这种NIR-CW诱导的双光子光致变色反应的起源是作用于金纳米颗粒电磁场（局域表面等离子体）的“增强效应”。DE与表面等离子体相互作用并从两个光子接收能量，这将其激发到可以引发开环反应的状态。
