A combined computational and experimental study of polynuclear Ru-TPPZ complexes: Insight into the electronic and optical properties of coordination polymers

Simona Fantacci, Filippo De Angelis, Jingjing Wang, Stefan Bernhard, Annabella Selloni

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Abstract

We report a combined experimental and computational study of polynuclear [Run(TPPZ)n+1]2n+ complexes, of interest in the field of photoactive polymers. The complexes with n = 1, 2, 3 and n > 5 have been synthesized and spectroscopically characterized. A red-shift of the visible band maximum from 2.59 to 2.03 eV is observed going from the monomer to the longer oligomeric species (n > 5). To characterize the geometries, electronic structure, and excited states of these complexes, density functional theory (DFT) and time-dependent DFT calculations on the [Run(TPPZ) n+1]2n+ series with n = 1-4 in solution have been performed. The agreement between experimental and calculated spectra is good, both in terms of absorption maximum energies and relative intensities for different values of n. For all the investigated complexes, we assign the main band in the visible region as a metal-to-metal plus ligand charge transfer (MMLCT) transition. The resulting excited states are delocalized throughout the entire complexes, as they originate from a superposition of π*(TPPZ)- t2g(Ru) states. The low-energy shoulder of the main visible absorption band, present in the experimental spectra for n > 1, is proposed to arise from spin-forbidden singlet-triplet transitions of similar MMLCT character, consistent with the observed enhancement of this feature in the spectra of the corresponding Os oligomers.

Original languageEnglish (US)
Pages (from-to)9715-9723
Number of pages9
JournalJournal of the American Chemical Society
Volume126
Issue number31
DOIs
StatePublished - Aug 11 2004

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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