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Development of Supramolecular Nanodevices Based on Photosynthetic Antennas

基于光合天线的超分子纳米器件的研制

基本信息

批准号：
15350107
负责人：
TAMIAKI Hitoshi
金额：
$ 7.62万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

As model chlorophylls in main light-harvesting antenna systems (chlorosomes) of green photosynthetic bacteria, coordinatable metal complexes (Mg, Zn and Cd) of cyclic tetrapyrroles possessing sterically less hindered hydroxy and hydrogen-bonded carbonyl groups were prepared by modifying naturally occurring chlorophylls and synthetic porphyrins using organic and bio-synthetic procedures. A variety of model compounds examined here self-aggregated to form large oligomers as well as natural chlorosomal chlorophylls did. The self-aggregates of synthetic molecules absorbed lights from visible to near-infrared region, which are wider than natural chlorosomes.To elucidate the supramolecular structures of the self-aggregates, ^<18>O-labeled vibrational and ^<13>C-labeled magic angle spinning nuclear magnetic spectroscopies were examined as well as electronic and circular dichroism absorption ones, indicating that coordination of 3^1-hydroxy group to central metal, hydrogen bond of 13-carbonyl group to the coordinated OH and π-π stacking among cyclic tetrapyrroles made the self-aggregates.Chemically and mechanically stable self-assemblies of synthetic chlorophylls were prepared using condensation of silanols (sol-gel method). The submicrometer-sized self-assemblies had the same optical properties as the self-aggregates in a homogeneous system. The capsules had negative charges on their surface in an aqueous solution as well as natural chlorosomes, and adsorbed on any positive charged surfaces. Such supramolecular systems are promising for construction of photoactive nanodevices.

本文采用有机和生物合成的方法，对天然存在的叶绿素和卟啉进行修饰，制备了具有空间位阻较小的羟基和氢键羰基的环四吡咯金属配位配合物（Mg、Zn和Cd），作为绿色光合细菌主要的捕光天线系统（叶绿体）中的模式叶绿素。这里检测的各种模型化合物自聚集形成大的低聚物以及天然的叶绿体叶绿素。合成分子的自聚集体吸收可见光到近红外波段的光，比天然叶绿体吸收的光宽。为明确自聚集体的超分子结构，采用^<18> o标记的振动和^<13> c标记的幻角自旋核磁波谱以及电子和圆二色吸收波谱分析表明，3^1-羟基与中心金属的配位、13-羰基与配位OH的氢键和环四吡罗之间的π-π堆积形成了自聚集体。采用硅烷醇缩合法（溶胶-凝胶法）制备了化学性质和机械性能稳定的自组装体。亚微米尺度的自组装体与均匀体系中的自聚集体具有相同的光学性质。在水溶液和天然叶绿体中，胶囊表面带负电荷，并吸附在任何带正电荷的表面。这种超分子体系在光活性纳米器件的构建中具有广阔的应用前景。