RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
J Phys Chem B. 2010 Jan 28;114(3):1227-32. doi: 10.1021/jp906625a.
Novel chiral amorphous molecular materials containing photoresponsive azobenzene moieties were designed and synthesized. These materials led to the formation of smooth and uniform thin films without grain boundaries. Photoirradiation of the thin film with linearly and elliptically polarized light caused trans-cis photoisomerization of the azobenzene moieties and resulted in an anisotropic orientation of the materials. Maximum change in a value of birefringence, Deltan, after irradiation of the linearly polarized light is about 0.08 with a response time of 10 s. However, when irradiation was ceased after photoinduced orientation, the value of Deltan decreased due to relaxation of the azobenzene moieties. Furthermore, these materials exhibited a high efficiency of a photoinduced polarization rotation over 30 deg mum(-1) after irradiation with the elliptically polarized light for 60 s. We also found that the efficiency depends on ellipticity of the incident light and on the thickness of the sample. The origin of the large change in the molecular orientation is the anisotropic arrangement of the azobenzenes in the terminal groups upon irradiation with the linearly and elliptically polarized light.
设计并合成了含有光响应偶氮苯部分的新型手性无定形分子材料。这些材料导致形成无晶界的光滑和均匀的薄膜。用线偏振光和椭圆偏振光照射薄膜会引起偶氮苯部分的顺反光异构化，导致材料的各向异性取向。线偏振光照射后双折射值的最大变化 Δn 约为 0.08，响应时间为 10 s。然而，光诱导取向后停止照射时，由于偶氮苯部分的松弛，Δn 值减小。此外，这些材料在 60 s 内用椭圆偏振光照射后，光诱导偏振旋转的效率超过 30 deg µm(-1)。我们还发现，效率取决于入射光的椭圆度和样品的厚度。分子取向的大变化源于线偏振光和椭圆偏振光照射时末端基团中偶氮苯的各向异性排列。
