New Materials for Coupling Electron and Ion Transfer Across Model Archaebacterial Membranes

基于平面细菌视紫红质膜的光电开关和存储器件的开发一直是国际研究工作的重点。 这些装置的使用是设想在各种模式识别系统，其中快速存储高密度的光学信息与长的存储寿命（1毫秒）是必需的。 虽然已经建立了使用细菌视紫红质的装置原型来实现这一点，但是它们的设计受到多激发态的稳定性、物理和吸收特性以及细菌视紫红质在平面阵列中的方向控制差的限制。 拟议的研究的目的是合成和表征一类新的材料，将耦合光化学诱导的电子和离子传输反应的取向，薄膜薄膜在光电器件中的应用。 将这些材料固定到光学透明的电极表面上将在这些材料中提供一定程度的光化学和电化学可调性，这是目前基于细菌跳蛋白的装置中所缺乏的。 短杆菌肽A-卟啉-醌（GAPQ三联体，在概念上模仿光合细菌和植物的膜结合反应中心，将被合成并掺入由模型古细菌双极膜脂质（bolalipids）组成的囊泡中。 这些材料将通过以下方式在复合三元组/类玻色子光化学系统中相互补充：1）使卟啉和醌在膜内矢量取向以产生具有氧化和还原表面的不对称膜结构，2）通过将末端供体和受体部分置于相对的膜界面来抑制初始电荷分离对的自湮灭，3）通过减小供体-受体分离距离来增加跨膜电子转移的速率，和4）通过结合单价离子通道以消散电势梯度的累积来补偿由跨膜电子转移引起的膜极化。 该提案描述了制备化学，结构和光化学表征，钠离子电导测量，旨在优化双极脂质膜的矢量电子和离子转移速率。 该提案的材料方面的重点是开发模块化的bolphoid和GAPQ合成途径，以便可以实现相对于界面反应性，有效的跨膜电荷分离和固体支持材料上的固定化的简易系统集成。 实验设计探测的三重态取向，离子通道特性，光化学动力学，和电子/离子耦合在各种GAPQ/bolphanoid复合膜配置使用激光闪光光解，差示扫描量热法，核磁共振，和电子显微镜技术也提出了。 这些研究的结果将被用来设计一个合适的系统，用于测试微孔和ITO支持。 ***

9319099 Thompson The development of optoelectronic switching and storage devices based on planar bacteriorhodopsin films has been the focus of intense international research efforts. Utilization of these devices is envisioned in a variety of pattern recognition systems where rapid storage of high densities of optical information with long storage lifetimes ( 1 ms) is required. Although device prototypes using bacteriorhopsin have been built that achieve this, their design is limited by the stability, photophysical and absorption characteristics of the multiple excited states, and poor directional control of bacteriorhdopsin in planar arrays. The objective of the proposed research is to synthesize and characterize a new class of materials that will couple photochemically induced electron and ion transport reactions in oriented, thin membrane films for application in optoelectronic devices. Immobilization of these materials onto optically transparent electrode surfaces will provide a degree of photochemical and electrochemical tunability in these materials that is currently lacking in the bacteriorhopsin-based devices. %%% Gramicidin A-porphyrin-quinone (GAPQ triads, patterned in concept after the membrane-bound reaction centers of photosynthetic bacteria and plants, will be synthesized and incorporated into vesicles composed of model archaebacterial bipolar membrane lipids (bolalipids). These materials will complement each other in a composite triad/bolalipid photochemical system by: 1) vectorially orienting the porphyrin and quinone within the membrane to produce an asymmetric membrane structure having both oxidizing and reducing surfaces, 2) inhibiting self-annihilation of the initially charge- separated pair by placing terminal donor and acceptor moieties at opposing membrane interfaces, 3) increasing the rate of transmembrane electron transfer by reducing the donor-acceptor separation distance, and 4) compensating for membrane polarization resulting fro m transmembrane electron transfer by incorporating a monovalent ion channel to dissipate the buildup of potential gradients. This proposal describes preparative chemistry, structural and photochemical characterization, and sodium ion conductance measurements aimed at optimizing vectorial electron and ion transfer rates across bipolar lipid membranes. The materials aspects of the proposal are focused on developing modular bolalipid and GAPQ synthetic pathways such that facile system integration with respect to interfacial reactivity, efficient transmembrane charge separation, and immobilization on solid support materials can be achieved. Experiments designed to probe the triad orientation, ion channel properties, photochemical kinetics, and electron/ion coupling in various GAPQ/bolalipid composite membrane configurations using laser flash photolysis, differential scanning calorimetry, nuclear magnetic resonance, and electron microscopy techniques are also proposed. The results of these investigations will then be used to devise a suitable system for testing on microporous and ITO supports. ***