Abstract
The solid complex Eu(III)-bathophenanthroline was synthesized and characterized by elemental analysis, IR spectra, and thermal analysis. The interaction of the Eu(III)-bathophenanthroline solid complex with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery and differential pulse polarography on a glassy carbon electrode. The formation of binary and ternary complexes of Eu(III) with nucleotides guanosine 5'-monophosphate (5'-GMP), adenosine 5'-monophosphate (5'-AMP), inosine 5'-monophosphate (5'-IMP), cytidine 5'-monophosphate (5'-CMP), or N-acetylamino acids (N-acetylaspartic acid, N-acetylhistidine, and N-acetylhistamine), and bathophenanthroline (BPhen) has been studied potentiometrically at (25.0 +/- 0.1) degrees C and an ionic strength of I = 0.1 mol.dm(-3) (KNO3) in 1.8% v/v ethanol-water mixture solvent. The formation of the normal and protonated binary and ternary complexes is inferred from the corresponding titration curves. The experimental conditions were selected such that self-association of the nucleotides and their complexes was negligibly small, that is, the monomeric complexes were studied. Initial estimates of the formation constants of the resulting species and the protonation constants of the different ligands used have been refined with the SUPERQUAD computer program. Confirmation of the formation of the ternary systems of the type Eu(III) bathophenanthroline N-acetylamino acids or nucleotides in solution has been carried out using UV-visible, cyclic voltammetry, square wave voltammetry, and emission spectrofluorometric measurements.