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Scientific article
Open access
English

Heteroleptic Ter–Bidentate Cr(III) Complexes as Tunable Optical Sensitizers

Published inInorganic Chemistry, vol. 57, no. 22, p. 14362-14373
Publication date2018
Abstract

In order to exploit Cr(III) coordination complexes as sensitizers in supramolecular energy-converting devices, the latter optical relays should display long-lived excited states, broad emission bands and tunable spatial and electronic connections to activator units. An ad-hoc versatile strategy has been therefore developed for the preparation of a family of luminescent pseudo-octahedral [CrN6] chromophores made up of ter-bidentate heteroleptic [Cr(phen)2(N-N')]3+ complexes, where phen is 1,10-phenanthroline and N-N' stands for ,'-diimine ligands possessing peripheral substituents compatible with both electronic tuning and structure extensions. As long as the ligand field in these [CrN6] chromophores remains sufficiently strong to avoid back intersystem crossing, photophysical studies indicate that the lifetime of the near-infrared emissive Cr(2E) excited state is poorly sensitive to 2 ligand-based electronic effects. On the contrary, a drop in symmetry, the coupling with high frequency oscillators and the implementation of sterical constraints in heteroleptic [Cr(phen)2(N-N')]3+ complexes affect both Cr(2E4A2) energies and Cr(2E) lifetimes. Altogether, [Cr(phen)2(phenAlkyn)]3+ (phenAlkyn = 5-ethynyl-1,10-phenanthroline) and [Cr(phen)2(dpma)]3+ (dpma = di(pyrid-2- yl)(methyl)amine) complexes mirror the favorable photophysical properties of homoleptic [Cr(phen)3]3+ and thus emerge as the best heteroleptic candidates for acting as sensitizers at room temperature, and below 100 K, respectively, in more complicated architectures.

Keywords
  • Chromium(III)
  • Complex
  • Heteroleptic
  • Lifetime
  • Sensitizer
  • Symmetry
Research group
Citation (ISO format)
DOISTAU, Benjamin et al. Heteroleptic Ter–Bidentate Cr(III) Complexes as Tunable Optical Sensitizers. In: Inorganic Chemistry, 2018, vol. 57, n° 22, p. 14362–14373. doi: 10.1021/acs.inorgchem.8b02530
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Article (Accepted version)
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ISSN of the journal0020-1669
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