Synthesis, characterization and molecular sensing capability of fac-[Re(CO)32-N,N-dpktsc)Cl] where dpktsc = di-2-pyridylketone thiosemicarbazone

Mohammed Bakir*, Ordel Brown

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

When di-2-pyridyl ketone thiosemicarbazone (dpktsc) was allowed to react with [Re(CO)5Cl] in toluene under reflux, fac-[Re(CO)32-N,N-dpktsc)Cl] was isolated in good yield. The identity of fac-[Re(CO)32-N,N-dpktsc)Cl] was established from the results of its elemental analysis, spectroscopic, and electrochemical properties. The infrared spectra of fac-[Re(CO)32-N,N-dpktsc)Cl] show the facial coordination of the carbonyl groups, and the pyridyl N,N-coordination of dpktsc. 1H NMR measurements on fac-[Re(CO)32-N,N-dpktsc)Cl] in d6-dmso and d6-acetone confirmed the pyridyl N,N-coordination of dpktsc, and showed strong solvent dependence as manifested by the sensitivity of thioamide and ammine protons to their surroundings. The electronic absorption spectra of fac-[Re(CO)32-N,N-dpktsc)Cl] in protophilic solvents (dmso and dmf) display two intra-ligand charge transfer (ILCT) transitions at 476 and 360 nm and in non-protophilic solvents a single ILCT transition at 346 nm in CH3CN and 342 nm in CH2Cl2. Reversible interconversion between fac-[Re(CO)32-N,N-dpktsc)Cl] and its conjugate base was established in protophilic solvents using a base to shift the equilibrium to the conjugate base and an acid to shift the equilibrium or conjugate base to the neutral form. Substrates in concentrations as low as 1 × 10-10 M can be detected and determined using protophilic solutions of fac-[Re(CO)32-N,N-dpktsc)Cl]. When MCl2 (M = Zn, Cd or Hg) was allowed to interact with fac-[Re(CO)32-N,N-dpktsc)Cl] in protophilic solvents, the intensity of the low energy ILCT band disappeared and a shift in the high energy ILCT electronic transition was observed that hints to the coordination of MCl2 to fac-[Re(CO)32-N,N-dpktsc)Cl]. Electrochemical measurements on fac-[Re(CO)32-N,N-dpktsc)Cl] in dmf showed sequential irreversible redox processes in accord with the electrochemical reduction or oxidation of the thiosemicarbazone moiety.

Original languageEnglish (US)
Pages (from-to)65-71
Number of pages7
JournalJournal of Molecular Structure
Volume930
Issue number1-3
DOIs
StatePublished - Jul 30 2009

Keywords

  • Di-2-pyridyl ketone
  • Electrochemistry
  • Rhenium
  • Sensors
  • Spectroscopy
  • Thiosemicarbazone metal complexes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

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