Zhang Chao-Feng, Chen Meng, Nakamura Chikashi, Miyake Jun, Qian Dong-Jin
Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433, China.
Langmuir. 2008 Dec 2;24(23):13490-5. doi: 10.1021/la8027622.
High-valency manganese (IV,V)-oxo porphyrins have been electrochemically generated and in situ spectrally characterized in multiporphyrin arrays, which were formed by an interfacial coordination reaction of Na2PdCl4 with manganese (III) tetrapyridylporphyrin (MnTPyP). Multilayers of the Pd-MnTPyP multiporphyrin arrays were obtained by the Langmuir-Blodgett (LB) method. The redox behaviors of manganese in the multiporphyrin arrays were pH-dependent. Spectroelectrochemical experiments revealed a reversible redox process between Pd-Mn(III)TPyP and its Mn(IV)-oxo species, but an irreversible process between Pd-Mn(III)TPyP and its Mn(V)-oxo species. The Pd-Mn(IV)TPyP multiporphyrin arrays could be spontaneously reduced to their Mn(III) complex, while the Pd-Mn(V)TPyP arrays were rather stable in basic solutions (pH > 10.5). However, when the Pd-Mn(V)TPyP multiporphyrin arrays were washed by or immersed in water, they were immediately reduced to their Mn(III) complex. Because these well-organized multiporphyrin arrays are of high thermal and chemical stability, they are potential molecular materials in the studies of natural and artificial catalytic processes as well as redox-based molecular switches.
高价态锰（IV，V）-氧代卟啉已在多卟啉阵列中通过电化学方法生成并进行了原位光谱表征，该多卟啉阵列是由Na2PdCl4与锰（III）四吡啶基卟啉（MnTPyP）发生界面配位反应形成的。通过朗缪尔-布洛杰特（LB）法获得了Pd-MnTPyP多卟啉阵列的多层膜。多卟啉阵列中锰的氧化还原行为依赖于pH值。光谱电化学实验表明，Pd-Mn（III）TPyP与其Mn（IV）-氧代物种之间存在可逆的氧化还原过程，但Pd-Mn（III）TPyP与其Mn（V）-氧代物种之间存在不可逆过程。Pd-Mn（IV）TPyP多卟啉阵列可自发还原为其Mn（III）配合物，而Pd-Mn（V）TPyP阵列在碱性溶液（pH > 10.5）中相当稳定。然而，当Pd-Mn（V）TPyP多卟啉阵列用水洗涤或浸泡时，它们会立即还原为其Mn（III）配合物。由于这些组织良好的多卟啉阵列具有高热稳定性和化学稳定性，它们在天然和人工催化过程以及基于氧化还原的分子开关研究中是潜在的分子材料。
