Aryloxo Derivatives of Phosphorus(V) Porphyrins. Synthesis, Spectroscopy, Electrochemistry, and Singlet State Properties
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- 作者：T. Anita Rao and Bhaskar G. Maiya
- 刊名：Inorganic Chemistry
- 出版年：1996
- 出版时间：August 14, 1996
- 年：1996
- 卷：35
- 期：17
- 页码：4829 - 4836
- 全文大小：248K
- 年卷期：v.35,no.17(August 14, 1996)
- ISSN：1520-510X
文摘
Aryloxo derivatives of phosphorus(V) porphyrins of the type[(TpTP)P(OR)B>2]+OH- whereTpTP is the dianionof tetra-p-tolylporphyrin and OR is an axial aryloxo(2,4-dimethylphenoxo, 4-methylphenoxo, phenoxo,4-nitrophenoxo, 4-(4-nitrophenoxy)phenoxo, or4-(2,4-dinitrophenoxy)phenoxo) ligand have been synthesizedandfully characterized by FAB-mass, UV-vis, fluorescence, infrared,and nuclear magnetic resonance (1H and31P)spectroscopies and cyclic voltammetric methods. Each new porphyrinshows a typical "normal UV-vis absorptionspectrum" indicating the presence of a P(V) ion in the porphyrincavity. The proton-decoupled 31P NMRsignalobserved for these compounds, between -194 and -200 ppm, suggeststhat there exists an octahedral coordinationaround the phosphorus atom, and this supposition is furthersubstantiated by the porphyrin ring-current-inducedupfield shifts observed for protons on the two axial aryloxo ligands inthe 1H NMR spectra. Cyclic voltammetricstudies reveal that each porphyrin undergoes two successive,one-electron reductions with the site of electrontransfer being the porphyrin ring. The fluorescence quantum yieldvalues of these porphyrins are found to besensitive to the nature of the aryloxo ligand and also to the solventpolarity. The singlet state properties of thesesystems have been discussed in light of both the fluorescence and theredox potential data.