Coordination Tendency of N-Acetylamino Acids, Nucleotides, and DNA Toward the Luminescent Bioprobes Tb(III)-Bathophenanthroline or Tb(III)-Anthracene-9-Carboxylic Acid

The solid complex Tb(III)-bathophenanthroline (Bphen) was synthesized and characterized by elemental analysis, IR spectra, and thermalanalysis. The formation of binary and ternary complexes of Tb(III) with N-acetylamino acids (N-acetylaspartic acid, N-acetylhistidine, and N-acetylhistamine), and Bphen or anthracene-9-carboxylic acid (9-ANCA) has been studied potentiometrically at (25.0 ± 0.1) °C and an ionic strength of I = 0.1 mol·dm–3. The results obtained confirmed the recognition of the investigated N-acetylamino acids by the luminescent probes used at the molecular level. The formation of binary and ternary complexes of Tb(III) with nucleotides guanosine 5′-monophosphate (5′-GMP), adenosine 5′-monophosphate (5′-AMP), cytidine 5′-monophosphate (5′-CMP), or N-acetylamino acids (N-acetylaspartic acid, N-acetylhistidine, and N-acetylhistamine) has been studied potentiometrically. Confirmation of the formation of the ternary systems of the type Tb(III)-Bphen-N-acetylamino acids or Tb(III)-9-ANCA-N-acetylamino acid in solution has been carried out using UV absorption spectra. The interaction of Tb(III)-Bphen with calf-thymus DNA (CT-DNA) was monitored using electrochemical measurements at a glassy carbon electrode via cyclic voltammetry and square wave voltammetry (SWV) in phosphate buffer (pH 7.00). The data reveal the preferential interaction of Tb(III)-Bphen with the guanine and adenine residues of CT-DNA. Fluorescence measurements have been carried out to investigate the interaction of Tb(III)-Bphen with CT-DNA and nucleotides 5′-GMP, 5′-AMP, and 5′-CMP.