C-13 magnetic relaxation rates and H-1 and C-13 paramagnetic shifts of Ni(II) complex of dopamine |
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Authors: | A Lai M Monduzzi G Saba M Casu G Crisponi |
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Institution: | Istituto Chimica Fisica e Industriale, Università di Cagliari, Via Ospedale 72, 09100 Cagliari, Italy;Istituto di Farmacologia, Università di Cagliari, Via Ospedale 72, 09100 Cagliari, Italy;Istituto Chimica Generale, Inorganica e Analitica, Università di Cagliagri, Via Ospedale 72, 09100 Cagliari, Italy |
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Abstract: | The 1H and 13C isotropic contact shifts and the 13C relaxation times of dopamine in aqueous solution have been measured in the presence of the Ni(II) ion. The pD dependence of the 1H and 13C paramagnetic shifts was also investigated. From the analysis of the shifts at pD = 6.5 and from the INDO MO calculations on selected models of dopamine radicals, a dominant σ delocalization mechanism of the spin density is proposed. From the spin distribution on the ligand carbon atoms, the metal centered as well as the ligand centered dipolar contributions of the modified Solomon—Bloembergen equation were calculated and an estimate of the correlation time τc was given. |
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