Self-Assembled Thin Solid Films of Dioctadecyldimethylammonium Cinnamate Lamella Units That Control the Photostationary State of E−Z Photoisomerizations
Self-Assembled Thin Solid Films of Dioctadecyldimethylammonium Cinnamate Lamella Units That Control the Photostationary State of E−Z Photoisomerizations
复制标题
控制 E−Z 光异构化光稳态的双十八烷基二甲基肉桂酸铵片层单元的自组装薄膜
作者：
O. Ohtani;R. Sasai;T. Adachi;I. Hatta;K. Takagi
在紫外光照射下，肉桂酸二十二烷基二甲基铵（C18反式和C18顺式）在自组装多层膜中发生E−Z光异构化。在这种情况下，通常在溶液中可以观察到的常见光稳定态（pss）在具有双分子（双层）单元片层结构的C18反式cin和C18顺式cin自组装材料膜的光解中没有看到。E-异构体和Z-异构体在长时间紫外线照射下也难以异构化，E/Z比值分别为73:27和10:90。然而，在单分子层-单元结构中，两种异构体均可获得相同的E/Z比（15:85）。在光异构化之前，在55°C左右热处理时，E/Z比突然发生变化，这意味着薄膜的热结构发生了变化。x射线衍射分析，差示扫描量热法，偏振红外和紫外-可见光谱研究。
UV illumination of dioctadecyldimethylammonium cinnamates (C18 trans-cin and C18 cis-cin) was found to result in the E−Z photoisomerization of the cinnamate moieties in self-assembling multilamella films. In the present case, a common photostationary state (pss), which can usually be observed in solution, was not seen in the photolysis of the self-assembled material films of C18 trans-cin and C18 cis-cin having a bimolecular (bilayer)-unit lamellar structure. Both the E- and Z-isomers are difficult to isomerize and exhibit different E/Z ratios, 73:27 and 10:90, respectively, even under prolonged UV irradiation. However, the same E/Z ratio (15:85) could be attained at the pss from either isomer in a monolayer-unit structure. The E/Z ratios were found to change abruptly upon heat treatment at around 55 °C before photoisomerization, implying a thermal structural change in the films. Analysis of X-ray diffraction, differential scanning calorimetry, and polarized IR and UV−vis spectroscopic investigations have...