Photosensitised electron transport across phospholipid vesicle walls
Photosensitised electron transport across phospholipid vesicle walls
复制标题
光敏电子穿过磷脂囊泡壁的传输
作者：
W. E. Ford;J. W. Otvos;M. Calvin
作为太阳能转换的一种手段，我们感兴趣的是色素类脂双层膜对水的光敏化分解，这些双层膜在相对的膜表面具有放氢和放氧催化剂。为了实现这一目标，我们目前的工作包括研究电子水溶液之间的光诱导电子转移反应。位于单层脂质体(囊泡)两侧的供体和受体，其中包含表面活性剂光敏剂。已经报道了以叶绿素为光敏剂的平面双层膜1或LiP‘osome~2-~的相关实验，但尚不清楚这些体系是否实现了储能。一个可能的例外是含有含有叶绿素和捕获的铁氰化物的囊泡的水的光氧化。4我们在此观察到，当乙二胺-N，N，N‘，N’-四乙酸乙酯(乙二胺-N，N‘，N’，N‘-四乙酸乙酯)溶解在含有表面活性类似物三(2，2’-联吡啶)RuTh2+的磷脂微囊的外水相中时，甲基紫精(L，L‘-二甲基-4，4’-联吡啶2+，简写为Mn2+)在外水相中被光敏还原。净反应，如图1所示，涉及EDTA的不可逆氧化；该反应是内能的，每摩尔EDTA消耗约20千卡。该反应在水溶液中被三(2，2-联吡啶)-RuTe~(2+)离子的光激发三重态敏化。有代表性的实验如图2所示。
As a means of solar energy conversion we are interested in the photosensitized decomposition of water with pigmented lipid bilayer membranes that have 02 and H2 evolving catalysts at opposing membrane surfaces. Our present work toward this goal involves the investigation of light-induced electron transfer reactions between aqueous solutions of electron. donors and acceptors that are on opposite sides of single-lamella liposomes (vesicles) with incorporated surfactant photosensitizers. Related experiments with planar bilayer membranes 1 or lip'osome~ 2-~ using chlorophyll as the photosensitizer'have been reported, but it is not clear that energy storage has been achieved in these systems. A possible exception is the photooxidation of water with vesicles that contain chlorophyll and trapped aqueous ferricyanide. 4 We report here that we have observed the photosensitized reduction of methylviologen (l, l'-dimethyl-4, 4'-bipyridinium2+, abbreviated to MV2+) dissolved in the exterior aqueous phase of a phospholipid vesicle dispe~ sion containing a surfactant analogue of tris (2, 2'-bipyridine) ruthenium2+ when ethylenediamine-N, N, N', N'-tetraacetate (EDTA) is dissolved in the enclosed aqueous phase of the vesicles. The net reaction, shown in Figure 1, involves the irreversible oxidation5 of EDTA; the reaction is endoergic by approximately 20 kcal per mole of EDTA consumed. This reaction is sensitized in aqueous solutions by the photoexcited triplet state of the tris (2, 2-bipyridine)-ruthenium2+ ion. 6 Representative experiments are illustrated in Figur~ 2.