Complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) in aqueous solution.

A study of complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) ions at 25 degrees C and in 0.5 M KNO(3) is reported. The amino-alcohols considered are 2-amino-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol and 2-amino-1,3-propanediol. sec-Buthylamine and 2-amino-1-methoxy-propane have been also considered for comparison. The results are discussed in terms of ligand structure, paying attention to the number of hydroxyl groups and to the length of the alkyl residual. A weak contribution of the alcoholic oxygen in the coordination of cadmium(II) and the presence of a mixed hydroxyl species in lead(II) containing systems are hypothesized.

Noncovalent interactions in ternary complexes of spermine and copper(II) with adenosine 5'-triphosphate and tripolyphosphate.

Thermodynamic characteristics pertinent to the formation equilibria of two ternary systems: 1) Copper(II), 4,9-diazadodecane-1,12-diamine (spermine, Spe), and adenosine 5'-triphosphate (ATP) and 2) Copper(II), Spe, and tripolyphosphate (TPP) have been determined by means of potentiometric and calorimetric techniques, together with the parent binary complex characteristics. Ternary complexes involving ATP can give information useful in the interpretation of bioenergetic reactions and of biological interactions between nucleic acids and polyamines. As a model system, the TPP-containing ternary complexes have been studied, together with the parent binary complexes. The thermodynamic study of these systems is very important because it can give information about the structural environment of the complexes; moreover, it can help in outlining different noncovalent interactions such as coulombic forces and hydrogen bonds.

Thermodynamics of simple and mixed complexes of copper(II) with adenosine 5'-monophosphate and spermine.

Thermodynamic parameters pertinent to the equilibria of ternary system copper(II), adenosine 5'-monophosphate (AMP), and 4,9-diazadodecane-1,12-diamine (Spermine, Spe) were determined by means of potentiometric and calorimetric techniques, together with the corresponding parent binary complex parameters. This system could be considered as a model in the study of more complicated biological systems. In particular, it could give useful evidence in the investigation of the interaction between tetramine and DNA. The experimental results seem to suggest that the major contribution in DNA stabilization by means of tetramines is due to the electrostatic interactions occurring between the protonated nitrogen atoms of the amine molecules and the phosphate groups of nucleotides in the nucleic chains.

Formation constants for the cobalt(II) chloride-1-nitroso-2-naphthol system in ethanol-benzene mixtures.

The values of conditional formation constants for the cobalt(II) chloride-1-nitroso-2-naphthol system were determined at 25 degrees in ethanol-benzene mixtures of different compositions by spectrophotometry in the visible region. Comparisons were made with the results previously obtained with the isomeric ligand 2-nitroso-1-naphthol. In both cases the L/M complexation ratio of the species found increases with increasing ethanol content of the medium.

Interaction of cobalt(II) chloride with 2-nitroso-1-naphthol in a 96:4 benzene-ethanol solution.

The cobalt(II) chloride-2-nitroso-1-naphthol system has been studied spectrophotometrically in a 96:4 (v v ) benzene-ethanol solution. Two species have been found, the M:L complexation ratios of which are 1:1 and 1:2. The concentration quotients of the formation equilibria are K(1) = 1.2 x 10(3) and K(2) = 1.4 x 10(4) respectively. The first step of the reaction is accompanied by a configurational change from a tetrahedral to an octahedral structure.