Ph-responsive switching of the near-infrared absorption of the water-soluble bis(o-diiminobenzosemiquinonato)platinum(II) complex

Atsuko Masuya, Nobuhiko Iki, Chizuko Kabuto, Yasunori Oba, Seigo Yamauchi, Hitoshi Hoshino

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The electronic structure of a water-soluble near-infrared (NIR)-absorbing complex was determined to be singlet diradical [PtII(L ISQ)2]2- [(LISQ)2- = o-diiminosulfobenzosemiquinonate radical] by X-ray diffraction and 1H NMR spectroscopy. Cyclic voltammetry (CV) showed redox reactions of [PtII-(LISQ)2]2- to give [Pt II(LISQ)(LIBQ)]- (E1/2 1 = -0.26 V vs. Fc+/Fc) and [PtII(L ISQ)(LPDI)]3- (E1/2 2 = -1.46 V) [(LIBQ)-= o-diiminosulfobenzoquinonate, (L PDI)3- = o-phenylenediiminesulfonate]. The monoradical structure of the latter was confirmed by electron paramagnetic resonance (EPR) spectroscopy. Splitting of the reduction wave of [PtII(L ISQ)(LIBQ)]- in CV and the weak EPR signal suggested the formation of a dimer. Because the rest potential of the solution exceeds Epa 1 at pH 4.0, the decrease in the NIR absorption at pH<4.0 can be attributed to the oxidation of [Pt II(LISQ)2]2- followed by dimerization.

Original languageEnglish
Pages (from-to)3458-3465
Number of pages8
JournalEuropean Journal of Inorganic Chemistry
Issue number22
DOIs
Publication statusPublished - 2010 Aug 1

Keywords

  • Absorption
  • Electronic structure
  • N ligands
  • Platinum
  • Radicals

ASJC Scopus subject areas

  • Inorganic Chemistry

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