Issue 48, 2010

Acid–base and electrochemical properties of manganesemeso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria

Abstract

The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-3-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of MnIIIVTE-2-PyP and MnIIIVTE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ∼2–13 the following species exist: (H2O)MnIITE-m-PyP4+, (HO)MnIITE-m-PyP3+, (H2O)2MnIIITE-m-PyP5+, (HO)(H2O)MnIIITE-m-PyP4+, (O)(H2O)MnIIITE-m-PyP3+, (O)(H2O)MnIVTE-m-PyP4+ and (O)(HO)MnIVTE-m-PyP3+ (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well.

Graphical abstract: Acid–base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria

Supplementary files

Article information

Article type
Paper
Submitted
01 Jun 2010
Accepted
06 Sep 2010
First published
04 Nov 2010

Dalton Trans., 2010,39, 11568-11576

Acid–base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria

T. Weitner, A. Budimir, I. Kos, I. Batinić-Haberle and M. Biruš, Dalton Trans., 2010, 39, 11568 DOI: 10.1039/C0DT00585A

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