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Abstract In this investigation, the azo dyes; 2-(3′-phenyl-5′-pyrazolyl azo) schaffer acid (la) and 2-(3′-phenyl-5′-pyrazolyl azo) resorcinol (Ib); were prepared through diazotizing 3-phenyl-5-aminopyrazole (PAP) and coupling the resulting diazonium salt with Schäffer acid and resorcinol respectively. The prepared azo dyes are characterized using both IR spectra and the elemental analysis (C, H, N and S). The prepared azo dyes are used as chromogenic reagents for the spectrophotometric determination of copper (II), nickel (II), cobalt (II) and zinc (II) ions. The conditional acid dissociation constants of these azo dyes (la and Ib) and the stability constants of its metal ion complexes have been determined by spectro-analytical methods. The effect of pH, time, organic solvent and the foreign ions on the spectrophotometric determination of these ions and their complexes with the azo dyes under study were studied. The stoichiometric ratio (M:L) of the formed complexes was also determined. The molar absorptivity, the Sandell's sensitivity values, the obeyance of Beers law and the stability constants of the formed complexes have been also determined and discussed.

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. [ABSTRACT FROM AUTHOR]

Potentiometric equilibrium measurements have been performed at (25.0 ± 0.1) °C and ionic strength I= 0.1 mol·dm−3KNO3for the interaction of the biologically important ligands N-acetylhistidine, N-acetyl l-leucine, N-acetylglutamic acid, N-acetylhistamine, N-acetylaspartic acid, and La(III), Gd(III), Sm(III), Tb(III), Eu(III), and Dy(III) with the nucleotides guanosine 5′-monophosphate (5′-GMP), cytedine 5′-monophosphate (5′-CMP), inosine 5′-monophosphate (5′-IMP), adenosine 5′-monophosphate (5′-AMP), adenosine 5′-diphosphate (5′-ADP), adenosine 5′-triphosphate (5′-ATP), and cytedine 5′-triphosphate (5′-CTP) in 1:1:1 and 1:2:1 ratios. The formation constants of various mixed ligand complexes were inferred from the potentiometric titration curves. Initial estimates of the formation constants of the resulting species and the formation constants of the different N-acetyl amino acid (NAA) and nucleotide (NU) complexes in metal ligand ratios 1:1 and 2:1 have been refined with the SUPERQUAD computer program. Confirmation of the formation of binary and ternary complexes of the type Ln(III)−NU−NAA and the possible recognition of the purine and pyrimidine mononucleotides by N-acetyl amino acid complexes of lanthanides in aqueous media have been carried out using UV spectroscopic and fluorimetric measurements. [ABSTRACT FROM AUTHOR]

The formation of binary and ternary complexes of Eu(III) with nucleobases (NB), guanine (2-amino-6-oxypurine), thymine (2,4-dihydroxy 5-methyl pyrimidine), adenine (6-aminopurine), uracil (2,4-dioxypyrimidine), and anthracene-9-carboxylic acid (ANCA) has been studied potentiometrically at (25.0 ± 0.1) °C and ionic strength I= 0.1 mol·dm−3(KNO3) in 10 % ethanol−water mixture solvent. The acid−base properties of the ligands were investigated and discussed. The formation of the 1:1, 2:1 binary, and 1:1:1 and 2:1:1 ternary complexes is inferred from the corresponding titration curves. The ternary complexes formed are monoprotonated complexes. The stability constants of the binary and ternary systems were evaluated. 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. The experimental conditions were selected such that self-association of the nucleobase and their complexes was negligibly small; that is, the monomeric normal and protonated complexes were studied. Confirmation of the formation of ternary complexes of the type Eu(III) (NB) (ANCA) in solution has been carried out using differential pulse polarography (DPP), square wave voltammetry (SWV), cyclic voltammetry (CV), UV−visible spectroscopic, and emission spectrofluorimetric measurements. [ABSTRACT FROM AUTHOR]

Potentiometric equilibrium measurements have been performed at (25.0 ± 0.1) °C and ionic strength I 0.1 mol·dm-3KNO3for the interaction of glycylglycine, glycylhistidine, glycylglycylglycine, glycylhistidylglycine, and Al(III), Ga(III), In(III), and Tl(I) with the biologically important secondary ligands bicine N,N-bis(2-hydroxyethyl)glycine, tricine N,N,N-tris(hydroxymethyl)methylglycine, PIPES piperazine-1,4-bis(2-ethanesulfonic acid), HEPES (N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid), and EPPS 4-(2-hydroxyethyl)piperazine 1-propanesulfonic acid in a 1:1:1 ratio. Ternary complexes of the type Al(III)−glycylglycine−guanosine, Al(III)−glycylglycine−guanosine 5‘-monophosphate (GMP), Al(III)−glycylglycylglycine−guanosine, Al(III)−glycylglycylglycine−GMP, Al(III)−glycylhistidine−guanosine, Al(III)−glycylhistidine−GMP, Al(III)−glycylhistidylglycine−guanosine, Al(III)−glycylhistidylglycine−GMP in a 1:1:1 ratio have been investigated. The experimental conditions were selected such that self-association of the nucleotide and their complexes was negligibly small; that is, the monomeric normal and protonated complexes were studied. The formation of various mixed ligand complexes was inferred from the potentiometric titration curves. Initial estimates of the formation constants of the resulting species and the protonation constants of the different peptides and zwitterionic buffers used have been refined with the SUPERQUAD computer program. Confirmation of the formation of ternary complexes of the type M−P−Z in solution has been carried out using differential pulse polarography, square wave voltammetry, cyclic voltammetry, and UV spectroscopic measurements. [ABSTRACT FROM AUTHOR]