Tuning the near-IR band energy and redox potentials of magnesium tetra(ferrocenyl)tetraazaporphyrins

Victor N. Nemykin, Elena A. Makarova, Jeff Grosland, Semyon V. Dudkin, Richard Dennison, Anatolii A. Purchel

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Magnesium 2(3),7(8),12(13),17(18)-tetraferrocenyl-5,10,15,20-tetraazaporphyrin (3), and magnesium 2(3),7(8),12(13),17(18)-tetracyano-3(2),8(7),13(12),18(17)-tetraferrocenyl-5,10,15,20-tetraazaporphyrin (4) complexes were prepared using template condensation reaction between magnesium butoxide and (Z)-dicyanovinylferrocene (1) and tricyanovinylferrocene (2), respectively. Redox and unusual optical properties of macrocyclic compounds 3 and 4 were investigated in details using UV-vis, MCD, electro-, and spectroelectrochemical methods as well as DFT and TDDFT calculations. It was shown that the HOMO in both compounds resembles Goutermans' a1u orbital (D4h symmetry), which is different from meso-ferrocenyl containing porphyrins. In both macrocycles 3 and 4 overlapping oxidation waves for ferrocene substituents were observed in electrochemical and spectroelectrochemical experiments. Electrochemically observed oxidation waves are rather broad because of the presence of positional isomers and span only ∼300 mV range in DCM/0.05 M TBAF system. Based on the excellent agreement between experimental UV-vis spectra and TDDFT predicted excitation energies, it was suggested that the low-energy NIR and visible regions are predominantly composed by the MLCT transitions with a signifcant π-π mixing.

Original languageEnglish (US)
Pages (from-to)792-803
Number of pages12
JournalJournal of Porphyrins and Phthalocyanines
Volume18
DOIs
StatePublished - Aug 2014

Keywords

  • Density functional theory
  • Electrochemistry
  • Ferrocene-containing tetraazaporphyrins
  • Magnetic circular dichroism
  • Spectroelectrochemistry
  • Time-dependent density functional theory

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