Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers

Ritika Gautam, Andrei V. Astashkin, Tsuhen M. Chang, Jason Shearer, Elisa Tomat

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The ability of tetrapyrrolic macrocycles to stabilize unpaired electrons and engage in π-π interactions is essential for many electron-transfer processes in biology and materials engineering. Herein, we demonstrate that the formation of π dimers is recapitulated in complexes of a linear tripyrrolic analogue of naturally occurring pigments derived from heme decomposition. Hexaethyltripyrrindione (H3TD1) coordinates divalent transition metals (i.e., Pd, Cu, Ni) as a stable dianionic radical and was recently described as a robust redox-active ligand. The resulting planar complexes, which feature a delocalized ligand-based electronic spin, are stable at room temperature in air and support ligand-based one-electron processes. We detail the dimerization of neutral tripyrrindione complexes in solution through electron paramagnetic resonance (EPR) and visible absorption spectroscopic methods. Variable-temperature measurements using both EPR and absorption techniques allowed determination of the thermodynamic parameters of π dimerization, which resemble those previously reported for porphyrin radical cations. The inferred electronic structure, featuring coupling of ligand-based electronic spins in the π dimers, is supported by density functional theory (DFT) calculations.

Original languageEnglish (US)
Pages (from-to)6755-6762
Number of pages8
JournalInorganic Chemistry
Volume56
Issue number11
DOIs
StatePublished - Jun 5 2017

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Magnetoelectronics
Dimers
Metals
dimers
Ligands
ligands
Dimerization
dimerization
electronics
metals
Paramagnetic resonance
Electrons
electron paramagnetic resonance
interactions
Porphyrins
pigments
Heme
biology
Pigments
porphyrins

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers. / Gautam, Ritika; Astashkin, Andrei V.; Chang, Tsuhen M.; Shearer, Jason; Tomat, Elisa.

In: Inorganic Chemistry, Vol. 56, No. 11, 05.06.2017, p. 6755-6762.

Research output: Contribution to journalArticle

Gautam, Ritika ; Astashkin, Andrei V. ; Chang, Tsuhen M. ; Shearer, Jason ; Tomat, Elisa. / Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers. In: Inorganic Chemistry. 2017 ; Vol. 56, No. 11. pp. 6755-6762.
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