Research on Porphyrin-Chlorin Co-assemblies and Revival of Their Dioxygen-coordination Abilities Photoirradiation

本研究的目的是恢复自氧化两亲性铁卟啉（III）的双氧配位能力第一年，合成了一种新的具有四个类磷脂取代基的脂质卟啉，它在水溶液中易于分散和自组装，得到直径为100 nm的球形双层膜。所制备的脂质卟啉囊泡在生理条件下能够可逆地结合和释放分子氧。红外光谱和分子圆二色谱证实了分子氧的配位结构。第二年，测定了双氧结合亲和力和双氧结合解离速率常数。研究了脂质卟啉双层膜中掺入的原卟啉衍生物的激发态到铁中心的电子转移过程。在外水相中存在电子给体（牺牲剂）的情况下，该反应变为不可逆反应，即脂质卟啉合铁（III）的光还原体系。例如，在由Zn（II）络合物和游离碱lipidporphyrins制成的共组装双层囊泡中，从单重态的porphyricatozinc（II）发生了高效的能量转移。这可能是一种新的水介质捕光模型。

The aim of this investigation is to revive the dioxygen-coordination ability of the auto-oxidized amphiphilic porphyrinatoiron(III) (lipidporphyrinatoiron(III)) by photoirradiation of the co-assembled free-base chlorine or porphyrin derivatives.In the first year, a new lipidporphyrin with four phospholipid-like substituents was synthesizes, It can be easily dispersed and self-assembled in aqueous system, to give spherical bi layer membranes with a diameter of 100 nm. The obtained lipidporphyrin vesicles can reversibly bind and release dioxygen under physiological conditions. The IR and MCD spectroscopies showed the coordination structure of the dioxygen. The dioxygen-binding affinity and dioxygen association and dissociation rate constants were also carefully measured.In the second year. electron transfer process from the excited state of the incorporated protoporphyrin derivative in the lipidporphyrin bilayer membrane to the iron(III) center was investigated. Under the co-existence of the electron donor (sacrificial regent) in outer aqueous phase, this reaction became irreversible, which is photoreduction system of the lipidporphyrinatoiron(III).During the research period, we found some new phenomena related on this project. For example, in co-assembled bi layer vesicles made of Zn(II) complex and free-base lipidporphyrins, high-efficient energy transfer took place from the singlet state of the porphyricatozinc(II). It could be a new light-harvesting model in aqueous medium.