IR spectroscopic investigations were conducted with poly-L-histidine (PLH) films, hydrous imidazole and pyrazole solutions and anhydrous ./V-methylimidazole with respect to protonation. Continuous absorption arises with increasing protonation and is maximally intensive with PLH, imidazole and 7V-methylimidazole when 50% protonated. The absorption indicates the formation of N H ® # , , N bonds. ...

The interaction between eriochrome black T and Li , Na , K ,Mg and Ca ions in acetone and dimethylsulphoxide solutions has been investigated spectrophotometrically. The formation constants of the resulting 1 : 1 complexes were determined and found to decrease in the order Mg >Ca >Li >K >Na in both solvents used. There is an inverse relationship between the stabilities of the complexes...

This article shows that the introduction of the Surface Complexation model into the »family« of theories that comprise the Theory of Colloid Stability makes that theory »absolute«. This means that one characterizes the electrical interfacial layer, e.g. by adsorption measurements, and calculates the equilibrium parameters, such as the equilibrium constants of protonation and deprotonation of am...

This study considers the possibility of astronomical detection of members of the CnO2H series; these are possible tracers of the parent polycarbon dioxide molecules, OCnO. Direct radio detection of these molecules is not possible owing to non existent or too small dipole moments. The structures of all stable isomers were determined according to protonation sites. Rotational constants and dipole...

The specific binding of five reduced Schiff base derived 7-amino-coumarin compounds with antitumor activity to human serum albumin, the principal binding protein of blood, was studied by fluorescence spectroscopy. Their conditional binding constants were computed and the reversible binding at the Sudlow's site I was found to be strong (KD∼0.03-2.09 μM). Based on the data albumin can provide a d...

Complexes of several transition metal ions with alpha-oximinoacetoacetyl pyridine-4-phenylthiosemicarbazone (H3OAPT) have been prepared. Attempts were made to elucidate their geometries by elemental analysis, molar conductance, magnetic measurements and by some spectroscopic (IR, ESR and electronic) techniques. All the investigated metal ions form mononuclear complexes except for CuII, which fo...

4-(2-Methylbutyl)aminodipicolinic acid (H(2)MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation constants (pK(a)'s) and photophysical measurements. The pK(a)'s were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescenc...

The stability constants of species present in the systems Ni(II)-pyridoxamine(pym)(A) and Ni(II)-pyridoxamine(pym)(A)-imidazole containing ligands(B) [B = imidazole(him),  benzimidazole(bim), histamine(hist) and L-histidine(his)] have been determined pH-metrically using the MINIQUAD computer program. The existence of the species NiAH, NiA and NiA2 was proven for the Ni(II)-pym(A)...

Protonated nucleobases have significant roles in facilitating catalytic functions of RNA, and in stabilizing different structural motifs. Reported pKa values of nucleobase protonation suggest that the population of neutral nucleobases is 10(3)-10(4) times higher than that of protonated nucleobases under physiological conditions (pH ∼ 7.4). Therefore, a molecular level understanding of various p...