A stepwise electron-transfer relay mimicking the primary charge separation in bacterial photosynthetic reaction center

被引:112
作者
Osuka, A
Marumo, S
Mataga, N
Taniguchi, S
Okada, T
Yamazaki, I
Nishimura, Y
Ohno, T
Nozaki, K
机构
[1] INST LASER TECHNOL,OSAKA 550,JAPAN
[2] OSAKA UNIV,FAC ENGN SCI,DEPT CHEM,TOYONAKA,OSAKA 560,JAPAN
[3] OSAKA UNIV,EXTREME MAT RES CTR,TOYONAKA,OSAKA 560,JAPAN
[4] HOKKAIDO UNIV,FAC ENGN,DEPT CHEM PROC ENGN,SAPPORO,HOKKAIDO 060,JAPAN
[5] OSAKA UNIV,FAC SCI,DEPT CHEM,TOYONAKA,OSAKA 560,JAPAN
关键词
D O I
10.1021/ja9520676
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The synthesis and excited-state dynamics are described for zinc-methylenechlorin-porphyrin-pyromellitimide triads, ZC-HP-I and ZC-ZP-I, and related dyads ZC-HP, ZC-ZP, HP-I, and ZP-I, where ZC, HP, ZP, and I indicate a zinc-methylenechlorin, a free-base porphyrin, a zinc-porphyrin, and pyromellitimide, respectively. In the steady-state fluorescence spectra of ZC-HP, ZC-HP-I, ZC-ZP, and ZC-ZP-I, only the emission from ZC is commonly observed, indicating efficient intramolecular singlet-singlet excitation energy transfer from HP or ZP to ZC. ZC-HP-I undergoes a stepwise electron-transfer relay: (1)(ZC)*-HP-1 --> (ZC)(+)-(HP)(-)-I --> (ZC)(+)-HP-(I)(-) with overall quantum yields of 0.70 and 0.07 in THF and DMF, respectively. In ZC-ZP-I, a pre-formed equilibrium between (1)(ZC)*-ZP-I and (ZC)(+)-(ZP)(-)-I is followed by a rapid charge-shift reaction to provide a secondary ion-pair state (ZC)(+)-ZP-(I)(-) with the overall quantum yield of 0.90 and 0.47 in THF and DMF, respectively. The intermediate ion-pair state (ZC)(+)-(ZP)(-)-I is stabilized enough so as to be clearly detected in DMF, while it is slightly higher in energy than (1)(ZC)* in THF, rendering its detection difficult.
引用
收藏
页码:155 / 168
页数:14
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