Novel Photochromism Using Thin Films of Ion-Pair Charce-Transfer Complexes

基于光致电子转移和热逆反应的新型光致变色研究得到了以下结果：1)合成了在1,1 ‘位置具有对称取代基和不对称取代基的4,4 ’-联吡啶离子离子对电荷转移配合物和以4,4 '-联吡啶离子为主链的聚合物。采用体积大、化学性质稳定的四[3,5-二（三氟甲基）苯]硼酸盐与4,4′-b-联吡啶离子形成盐，具有特异性离子对电荷转移（CT）吸收。2) Langmuir-Blodgett薄膜和聚合物铸膜的制备研究了具有对称取代基和不对称取代基的4,4 '-联吡啶离子在花生四酸混合物中的单层性质。制备了质量较好的y型Langmuir-Blodgett （LB）薄膜。采用浇铸法制备了非常薄的透明聚合物薄膜。(3)离子对电荷反式激发下的新型光致变色现象。在真空中，LB和聚合物薄膜在CT激发下，由于4,4 '-联吡啶自由基阳离子的形成，其颜色由淡黄色变为蓝色。在温度和微环境的影响下，蓝色在暗色中可逆地消失，在20^ C时，LB中tau _<1/e> =4 h，聚合物薄膜中tau _<1/e> = 72 h。颜色的变化重复了很多次。4) 4,4′-联吡啶自由基阳离子取向的分子调控研究了LB膜辐照前后的极化吸收光谱。从极化和入射角的依赖关系上，首次证明了4,4 '-联吡啶自由基阳离子的分子取向受取代基的控制。5)利用光波导技术对颜色变化的高灵敏度检测利用氦氖激光器实现了约150倍的灵敏度提高。成功地观察了玻璃光波导上超薄薄膜（约20 nm）的颜色变化。6)聚合物4,4′-联吡啶盐铸膜的光学记录聚合物膜的蓝态寿命明显长于LB膜。结果表明，在0^ C以下，光写入状态保持无衰减，并在较高温度下被擦除。少

The following results were obtained from the present research on novel photochromism based on the photoinduced electron transfer and thermal reverse reactions.1) Synthesis of ion-pair charge-transfer complexes4, 4'-Bipyridinium ions with symmetrical and asymmetrical substituents at 1, 1'-positions and polymers containing 4, 4'-bipyridinium ions as part of the main chain were synthesized. High bulk and chemically stable tetrakis [3,5-bis (trifluoromethyl) phenly] borate was used to form salts with 4, 4'-b-bipyridinium ions, which showed specific ion-pair charge-transfer (CT) absorption.2) Preparation of Langmuir-Blodgett films and polymer cast filmsMonolayer properties of 4, 4'-bipyridinium ions with symmetrical and asymmetrical substituents were studied in mixtures with arachidic acid. Y-type Langmuir-Blodgett (LB) films with good quality were deposited. Very thin transparent polymer films were prepared by a casting method.3) Novel photochromism upon excitation of ion-pair charge-trans … More fer bandUpon CT excitation of LB and polymer films in vacuo resulted in colour changes from pale yellow to blue due to the formation of 4, 4'-bipyridinium radical cations. The blue colour disappeared in dark reversibly with lifetimes depending on temperature and microenvironment, tau _<1/e> =4 h in LB and 72 h in polymer films at 20^ﾟC. The colour change was repeated for many times.4) Molecular control of the orientation of 4, 4'-bipyridinium radical cationsPolarized absorption spectra were measured before and after irradiation of LB films. From polarization and incident angle dependences, it was demonstrated for the first time that the molecular orientation of 4, 4'-bipyridinium radical cations was controlled by the substituents.5) Highly sensitive detection of colour changes by optical waveguide techniqueAbout 150-fold increase of sensitivity was achieved by this technique using a He-Ne laser. Colour changes in ultra thin films (about 20 nm) cast on a glass optical waveguide were successfully observed.6) Optical recording by cast films of polymeric 4, 4'-bipyridinium saltsThe lifetime of blue state in polymer films were considerably longer than in LB films. It was demonstrated that the optically written state was kept without decay below 0^ﾟC and was erased at higher temperatures. Less