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

1)合成了4，4‘-联吡啶离子对电荷转移络合物，合成了主链上含有对称和不对称取代基的4，4’-联吡啶离子聚合物。用高体积、化学稳定的四[3，5-二(三氟甲基)苯基]硼酸盐与4，4‘-b-联吡啶离子形成盐，表现出特殊的离子对电荷转移(CT)吸收。2)制备Langmuir-Blodgett膜和聚合物流延膜研究了具有对称和不对称取代基的4，4’-联吡啶离子在花生酸混合溶液中的单层性质。制备了质量良好的Y型Langmuir-Blodgett(LB)薄膜。采用浇铸法制备了超薄透明聚合物薄膜。3)离子对电荷传递…激发下的新型光致变色在真空中，由于4，4‘-联吡啶自由基阳离子的形成，在CT激发下，LB膜和聚合物膜的FER峰较大，导致颜色由淡黄色变为蓝色。随着温度和微环境的不同，蓝光在黑暗中可逆地消失，在20ﾟC下，T_u_t；lt；1/e&gt；=4h，在聚合物膜中为72h。4)4，4‘-联吡啶自由基阳离子取向的分子控制。从偏振和入射角的关系，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)用光波导法高灵敏地检测颜色变化。6)聚合物4，4‘-联吡啶盐浇铸膜的光记录聚合物膜的蓝态寿命明显长于LB膜。结果表明，光学写入态在0ﾟC以下没有衰变，在更高的温度下被擦除。较少

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