Reversible and pH dependent photophysical properties of mixed-ligand Ru(II) complexes containing 2,2′-bipyridine and nitrosobarbiturate: Experimental and theoretical approach

Abstract

A ruthenium(II) complex of type [Ru(bpy)2(L′H)] ·PF6 1 (L′H = 5-Nitroso-pyrimidine-2,4,6-trione, is prepared by the reaction of [1,5-dihydro-5-[5-pyrimidine-2,4(1H,3H)-dionyl]-2H- chromeno[2,3-d] pyrimidine- 2,4(3H)-dione)]) LH4 with [Ru(bpy) 2(NO3)2] (prepared in situ). It is characterized using elemental analyses, spectroscopic and single crystal X-ray diffraction techniques. This complex is converted in another complex of type [Ru(bpy)2(L′)] 2 by the addition of an aqueous solution of NaOH. The complex 2 turns back to complex 1 after its neutralization by the addition of an aqueous solution of HCl. The reversible conversion of complexes 1 and 2 in each other is monitored using their UV-Vis and luminescence spectra. Quantum chemical calculations using density functional theory (DFT) method corroborates transfer of electron density from nitrosobarbiturate to metal ion leading the formation of complex 2. © 2013 Elsevier B.V.