On the electronic structure of nitro-substituted bipyridines and their platinum complexes

Paul R. Murray*, Stephen Crawford, Alice Dawson, Alexander Delf, Calum Findlay, Lorna Jack, Eric J. L. McInnes, Salma Al-Musharafi, Gary S. Nichol, Iain Oswald, Lesley J. Yellowlees

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We report the preparation and electrochemical studies of a systematic series of mono-and di-nitro-substituted 2,2'-bipyridine (bipy) compounds [x-NO2-bipy (x = 3,4) and x,x'-(NO2)(2)-bipy (x,x' = 3, 4, 5)] and their complexes with platinum(II), [Pt(x-NO2-bipy)Cl-2] and [Pt(x,x'-(NO2)(2)-bipy)Cl-2]. The effect of the number and substitution pattern of the nitro groups on the low-lying acceptor molecular orbitals (involved in charge transfer transitions) is probed by in situ UV/Vis/NIR and EPR spectroelectrochemical methods, supported by DFT calculations. The LUMOs of x-NO2-bipy (x = 3-5) are largely localised on the NO2-pyridyl moiety; this is also true of their {PtCl2} complexes but with a small but significant shift of electron density from the nitro groups. The LUMOs of x,x'-(NO2)(2)-bipy with x = 3 and 5 are delocalised over both NO2-pyridyl rings, but for 4,4'-(NO2)(2)-bipy is localised on a single NO2-pyridyl ring. In all cases the LUMO of the [Pt(x,x'-(NO2)(2)-bipy)Cl-2] complexes is delocalised over both nitro-pyridyl rings. For all complexes, the 4(4') derivatives allows greatest overlap with metal valence orbitals in the LUMO.

Original languageEnglish
Pages (from-to)201-207
Number of pages7
JournalDalton Transactions
Volume41
Issue number1
DOIs
Publication statusPublished - 2012

Keywords

  • SENSITIZED SOLAR-CELLS
  • RUTHENIUM(II) COMPLEXES
  • DYES
  • LIGANDS
  • EPR
  • 4,4-DINITRO-2,2-BIPYRIDINE
  • POTENTIALS
  • RESONANCE
  • SPECTRA
  • ENDOR

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