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Synthesis, Structure, Spectroscopic, and Electrochemical Properties of Highly Fluorescent Phosphorus(V)– meso ‐Triarylcorroles
Author(s) -
Ghosh Avijit,
Ravikanth Mangalampalli
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103226
Subject(s) - hexacoordinate , chemistry , pyridine , tetraphenylporphyrin , fluorescence , molecule , electrochemistry , dissociation (chemistry) , solvent , crystallography , photochemistry , medicinal chemistry , organic chemistry , porphyrin , physics , electrode , quantum mechanics , silicon
The synthesis, spectroscopic, and electrochemical properties of seven new P V – meso ‐triarylcorroles ( 1 – 7 ) are reported. Compounds 1 – 7 were prepared by heating the corresponding free‐base corroles with POCl 3 at reflux in pyridine. Hexacoordinate P V complexes of meso ‐triarylcorroles were isolated that contained two axial hydroxy groups, unlike the P V complex of 8,12‐diethyl‐2,3,7,13,17,18‐hexamethylcorrole, which was pentacoordinate, or the P V complex of meso ‐tetraphenylporphyrin, which was hexacoordinate with two axial chloro groups. 1 H and 31 P NMR spectroscopy in CDCl 3 indicated that the hexacoordinated P V – meso ‐triarylcorroles were prone to axial‐ligand dissociation to form pentacoordinated P V – meso ‐triarylcorroles. However, in the presence of strongly coordinating solvents, such as CH 3 OH, THF, and DMSO, the P V – meso ‐triarylcorroles preferred to exist in a hexacoordinated geometry in which the corresponding solvent molecules acted as axial ligands. X‐ray diffraction of two complexes confirmed the hexacoordination environment for P V – meso ‐triarylcorroles. Their absorption spectra in two coordinating solvents revealed that P V – meso ‐triarylcorroles showed a strong band at about 600 nm together with other bands, in contrast to P V –porphyrins, which showed weak bands in the visible region. These compounds were easier to oxidize and more difficult to reduce compared to P V –porphyrins. These compounds were brightly fluorescent, unlike the weakly fluorescent P V –porphyrins, and the quantum yields for selected P V –corroles were as high as Al III and Ga III corroles, which are the best known fluorescent compounds among oligopyrrolic macrocycles.