Yushmanov V E, Imasato H, Tominaga T T, Tabak M
Instituto de Química de São Carlos, Universidade de São Paulo, Brasil.
J Inorg Biochem. 1996 Mar;61(4):233-50. doi: 10.1016/0162-0134(95)00071-2.
The ionization, mu-oxo-dimerization and axial ligation equilibria of free bases, iron(III) and manganese(III) derivatives of meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS4) and meso-tetrakis(4-N-methyl-pyridiniumyl)porphyrin (TMPyP) in aqueous solution are studied by 1H NMR and electronic absorption spectroscopy. At physiological pH, Fe(III) complexes of TMPyP and TPPS4 exist predominantly as dimers and may undergo transition to low spin species upon binding to biomolecules, whereas Mn(III) complexes are essentially monomeric. Dicyano and bis-imidazole complexes of FeTMPyP and FeTPPS4 are low spin monomer adducts in the pH range 2.0 to 11.2. No low spin dimeric complexes were found. The low spin monocyano and high spin mono-imidazole complexes of FeTMPyP are formed in acidic and alkaline media, respectively. T1-relaxation enhancement of water protons at 200 MHz induced by FeTPPS4 falls dramatically in the sequence high spin >> dimeric > low spin form.
通过¹H NMR和电子吸收光谱研究了中-四（对-磺基苯基）卟啉（TPPS4）和中-四（4-N-甲基吡啶基）卟啉（TMPyP）的游离碱、铁（III）和锰（III）衍生物在水溶液中的电离、μ-氧二聚化和轴向配位平衡。在生理pH值下，TMPyP和TPPS4的铁（III）配合物主要以二聚体形式存在，并且在与生物分子结合时可能会转变为低自旋物种，而锰（III）配合物基本上是单体。FeTMPyP和FeTPPS4的二氰基和双咪唑配合物在pH值2.0至11.2范围内是低自旋单体加合物。未发现低自旋二聚体配合物。FeTMPyP的低自旋单氰基配合物和高自旋单咪唑配合物分别在酸性和碱性介质中形成。由FeTPPS4在200 MHz下引起的水质子的T1弛豫增强在高自旋>>二聚体>低自旋形式的序列中急剧下降。
