Synthesis and characterization of some new mononuclear ruthenium complexes containing 4-(un)substituted dipyridylpyrazole ligands

A mononuclear ruthenium complex [Ru(bpy)2(bpp)](PF6) (1) and its halogenated and nitro derivatives [Ru(bpy)2(Xbpp)](PF6) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl)pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO2, 5) have been synthesized and characterized by 1H NMR, 13C NMR, HRMS, elemental analysis. Complexes 2–5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described. The results presented here reveal that the introduction of Cl, Br, I and NO2 groups to the coordinated bpp− ligand makes the absorption and emission maxima of the parent complex 1 blue-shifted, the oxidation potential of the RuII/RuIII couple increased and the pKa value decreased obviously. In addition, significant quenching of the emission by these groups is also observed.

A mononuclear Ru complex [Ru(bpy)2(bpp)](PF6) (1) and its halogenated and nitro derivatives [Ru(bpy)2(Xbpp)](PF6) (bpy = 2,2′-bipyridine; bpp = 3,5-bis(2-pyridyl) pyrazole; X = Cl, 2; X = Br, 3; X = I, 4; X = NO2, 5) have been synthesized and characterized by 1H NMR, 13C NMR, HRMS and elemental analysis. Complexes 2–5 have been further confirmed by X-ray diffraction. Their UV–Vis and emission spectroscopies, electrochemical measurements and acid–base properties are described.Figure optionsDownload as PowerPoint slide