Studies on intra-supramolecular and intermolecular electron-transfer processes between zinc naphthalocyanine and imidazole-appended fullerene
Studies on intra-supramolecular and intermolecular electron-transfer processes between zinc naphthalocyanine and imidazole-appended fullerene
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DOI：
10.1002/cphc.200200540
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发表时间：
2003-04-14
期刊：
影响因子：
2.9
通讯作者：
D'Souza, F
中科院分区：
文献类型：
--
作者：
El-Khouly, ME;Rogers, LM;D'Souza, F
在非配位溶剂甲苯和邻二氯苯中，研究了含咪唑配位ligand(2-(4-imidazolylphenyl)-fullereropyrrolidine，C(60)Im的萘菁锌、纳米锌和富勒吡咯烷轴向配位形成的自组装给体-受体二元体在非配位溶剂甲苯和邻二氯苯中的氧化还原和光化学行为，并与配位溶剂苯腈中的分子间电子转移过程进行了比较.光吸收和从头算B3LYP/3-21G(*)计算表明，在ZnNc和C(60)Im实体之间形成了自组装的超分子11二聚体。在优化的结构中，HOMO完全位于ZnNc实体上，而LUMO完全位于富勒烯实体上。循环伏安研究表明，在0.1M四丁基高氯酸铵存在下，邻二氯苯共发生了7个单电子氧化还原过程。用光发射和瞬时吸收技术对激发态电子转移过程进行了监测。从皮秒瞬时吸收光谱研究中获得了自由基离子对(C(60)Im(.-)：ZnNc(.+))形成的直接证据，表明电荷从单重态激发的ZnNc部分分离到C(60)Im部分。甲苯和邻二氯苯的电荷分离和电荷复合速率分别为1.4x10(10)S(-1)和5.3x10(7)S(-1)和8.9x10(9)S(-1)和9.2x10(7)S(-1)。在苯腈中，分子间电子从激发态三重态向C(60)Im转移，猝灭过程的二级速率常数k(Q)(三重态)为5.3×10(8)M-1 S(-1)。
Spectroscopic computational redox, and photochemical behaviour of a self-assembled donor-acceptor dyad formed by axial coordination of zinc napthalocyanine, ZnNc, and fulleropyrrolidine bearing an imidazole coordinating ligand(2-(4-imidazolylphenyl)-fullereropyrrolidine, C(60)Im) was investigated in noncoordinating solvents, toluene and o-dichlorobenzene, and the results were compared to the intermolecular electron transfer processes in a coordinating solvent, benzonitrile. The optical absorption and ab initio B3LYP/3-21G(*) computational studies revealed self-assembled supramolecular 11 dyad formation between the ZnNc and C(60)Im entities. In the optimized structure, the HOMO was found to be entirely located on the ZnNc entity while the LUMO was found to be entirely on the fullerene entity. Cyclic voltammetry studies of the dyad exhibited a total of seven one-electron redox process in o-dichlorobenzene, with 0.1M tetrabutylammonium perchlorate. The excited state electron-transfer process were monitored by both optical-emission and transient-absorption techniques. Direct evidence for the radical-ion-pair (C(60)Im(.-) :ZnNc(.+)) formation was obtained from picosecond transient-absorption spectral studies, which indicated charge separation from the singlet-excited ZnNc to the C(60)Im moiety. The calculated rates of charge separation and charge recombination were 1.4 x 10(10) s(-1) and 5.3 x 10(7) s(-1) in toluene and 8.9 x 10(9) s(-1) and 9.2 x 10(7) s(-1) in o-dichlorobenezene, respectively. In benzonitrile, intermolecular electron transfer from the excited triplet state of ZnNc to C(60)Im occurs and the second-order rate constant (k(q)(triplet)) for this quenching process was 5.3 x 10(8) M-1 s(-1).