ELECTROCHEMICAL INVESTIGATION OF THE REDOX PROPERTIES OF BACTERIOCHLOROPHYLL AND BACTERIOPHEOPHYTIN IN APROTIC-SOLVENTS
ELECTROCHEMICAL INVESTIGATION OF THE REDOX PROPERTIES OF BACTERIOCHLOROPHYLL AND BACTERIOPHEOPHYTIN IN APROTIC-SOLVENTS
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DOI：
10.1021/ja00519a023
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发表时间：
1979-01-01
影响因子：
15
通讯作者：
VANDUYNE, RP
中科院分区：
文献类型：
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作者：
COTTON, TM;VANDUYNE, RP
了解溶剂对细菌叶绿素（BChl）和细菌叶绿素（BPheo）氧化还原特性的影响，对于理解它们在光合细菌的初级光化学中作为中间电子受体的可能作用是重要的。利用循环伏安法（CV）和循环差分脉冲伏安法（CDPV）对红红螺旋藻化合物在几种非质子溶剂中的电化学行为进行了研究，结果表明，BChl的聚集和连接相互作用对其氧化还原电位有显著影响。在二氯甲烷中，BChl的1电子还原电位正移动了200 mV，与BPheo在相同溶剂中的还原电位几乎相同。这种变化最容易解释为在这种溶剂中存在BChl聚集体。1电子氧化电位相对不受聚集的影响。相反，在四氢呋喃（2分子溶剂配位到BChl的Mg原子上）中形成6配位的BChl对1电子还原电位和1电子氧化电位都有影响，其中对后者的影响最大。溶剂对BPheo氧化还原性能的影响要小得多，这与它无法进行类似于BChl的聚集和配位相互作用相一致。
Knowledge of solvent effects on the redox properties of bacteriochlorophyll (BChl) and bacteriopheophytin (BPheo) is important for understanding their possible role(s) as intermediate electron acceptors in the primary photochemistry of photosynthetic bacteria. An investigation of the electrochemical behavior of these compounds [from Rhodospirillum rubrum] by cyclic voltammetry (CV) and cyclic differential pulse voltammetry (CDPV) in several aprotic solvents showed that BChl aggregation and ligation interactions have a significant effect on its redox potentials. In methylene chloride, the 1-electron reduction potential of BChl shifted positively by 200 mV to a value nearly identical with that of BPheo in the same solvent. The shift is most readily explained by the presence of BChl aggregates in this solvent. The 1-electron oxidation potential is relatively unaffected by aggregation. In contrast, the formation of 6-coordinate BChl in tetrahydrofuran (2 molecules of solvent coordinated to the Mg atom of BChl) affects both the 1-electron reduction and 1-electron oxidation potential, with the greatest effect on the latter. Solvent effects on the redox properties of BPheo were much smaller, a finding consistent with its inability to undergo aggregation and coordination interactions similar to those of BChl.