Effects of Substituents on the Spectral and Redox Properties of Cadmium(II) Texaphyrins

Bhaskar G. Maiya, Thomas E. Mallouk, Gregory Hemmi, Jonathan L. Sessler

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

The synthesis, electronic absorption spectra, and electrochemistry of cadmium(II) texaphyrins substituted with various electron-donating or electron-withdrawing groups are described. The one-electron oxidation and reduction potentials and the energies of the lowest energy absorption band maxima (λQ754–797 nm) are sensitive to the nature of substituents attached to the phenyl ring of these novel pentadentate macrocycles. Cyclic voltammetric data revealed that weakly binding counterions associated with these monopositive complexes (e.g. ClO4or NO3) dissociate upon one-electron reduction; the reduction peaks are irreversible to quasi-reversible in these cases. However, in the presence of strongly binding chloride ion (Cl) or nitrogen bases (e.g. pyridine), the reduction process is electrochemically revesible and ligand dissociation does not occur on the cyclic voltammetric time scale. A linear relationship between the frequency of the lowest energy absorption maximum and the difference in potentials for the first oxidation and reduction processes (1.54–1.40 V) exists in these systems. A similar relationship was also found for those texaphyrin complexes in which the phenyl group is replaced by a naphthyl, phenanthryl, or dicyano group. These results are discussed on the basis of the known spectral and redox features of metalloporphyrins.

Original languageEnglish (US)
Pages (from-to)3738-3745
Number of pages8
JournalInorganic chemistry
Volume29
Issue number19
DOIs
StatePublished - Jan 1 1990

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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