Publication: Triplet (S = 1) Ground State Porphyrin-Verdazyl Radical Conjugates: Synthesis, Spectroscopy and Magnetic Properties
All || By Area || By Year| Title | Triplet (S = 1) Ground State Porphyrin-Verdazyl Radical Conjugates: Synthesis, Spectroscopy and Magnetic Properties | Authors/Editors* | P. K. Poddutoori, M. Pilkington, A. Alberola Catalan and A. van der Est |
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| Where published* | Journal of the American Chemical Society |
| How published* | Journal |
| Year* | 2007 |
| Volume | -1 |
| Number | -1 |
| Pages | |
| Publisher | |
| Keywords | |
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| Abstract |
The beta-substitued paramagnetic metalloporphyrin-verdazyl radical conjugates 2-(6-Oxo-1,5-dimethylverdazyl)-5,10,15,20-tetratolylvanadyl(IV) porphyrin (VOVz) and 2-(6-Oxo-1,5-dimethylverdazyl)-5,10,15,20-tetratolylcopper(II) porphyrin (CuVz) have been synthesized and characterized in solution and in bulk by various spectroscopic, electrochemical and magnetic methods. The UV-visible and electrochemical data suggest that the electronic configuration of the pophyrin pi-electrons is perturbed by the verdazyl radical substituent. However, the crystal structure of CuVz shows that the verdazyl group causes no significant distortion of the planarity of the porphyrin ring. The structure also shows that the verdazyl group is oriented almost perpendicular to porphyrin plane to avoid steric interaction with the adjacent meso-tolyl group. The EPR spectra of CuVz and VOVz in toluene solution show that the ground state of the complexes is a triplet (S =1) in which the copper(II) or vanadyl(IV) metallic centre interacts with the verdazyl radical. Magnetic susceptibility data indicate that the bulk material is paramagnetic with very weak coupling between neighbouring complexes. From the X-ray structure it is apparent that the weak coupling is a result of the fact that the verdazyl substituents are prevented from coming into close contact with each other the intervening tolyl groups. |
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