Light scattering studies on acacia catechuic acid in ethanol‐water‐mixtures

Abstract

The light scattering properties of Acacia Catechuic Acid (ACA) was studied -in aqueous mixture of ethanol containing 0.02 mole/l. KC1. There was hardly any effect upto 25% alcohol, above which the molecular weight appeared to increase gradually till 50% alcohol in the mixture and at 55% there was precipitation of the acid.The root mean square end-to-end distance remained almost unaffected at lower concentration and reached a minimum value at about 25 yo (3052 A) beyond which there was considerable increase reaching up t o a maximum limit of 3597 A at 50% (as against 3270 A in water). This interesting behaviour of ACA in the above mentioned system could be explained in the light of the FLORY-FOX equation in conjunction with association of molecules by their hydrophobic groups which was favoured by addition of alcohol. Alcohol, however, at low concentrations did not appear to affect the character of the solvent to a great degree but beyond about 25%, the solvent behaved as a poor one. ZUSAMMENFASSUNG: Die Lichtstreuung von Akazien-Catechu-Saure (ACA) in waDrig-athanolischen Losungen (mit 0,02 mol/Z. KCl) wurde untersucht. Bis zu 25 yo Athanolkonzentration in der Losung war praktisch keine Wirkung zu erkennen. Bei hoheren Alkoholkonzentr ationen (bis 50 yo) beobachtet man eine stetige Zunahme des Molekulargewichts, und bei 55 V O~. -~~ fallt die Saure aus. Die Wurzel aus dem Quadrat des mittleren Fadenendenabstandes war bei niedrigen Alkbholkonzentrationen konstant (3270 A), fie1 dann bis zn einem Minimum bei 25% Alkohol ab (3052 A), nm dann wieder bis zu einem Grenzwert von 3597 A bei 50% hithanol zu steigen.Dieses interessante Verhalten der ACA laDt sich an Hand der Gleichung von FLORY und FOX erklaren, wenn man aul3erdem beriicksichtigt, daD die ACA-Molekule uber ihre hydrophoben Gruppen assoziieren konnen, was durch die Zugabe des Alkohols begiinstigt wird ; Losungen mit mehr als 25 yo Alkohol sind schlechte Losungsmittel fur ACA.

Synthesis, structure, and spectral and magnetic properties of trinuclear copper(II) complexes bridged by glyoximate groups

“…The complex molecule consists of a trinuclear cation and nitrate ions and has the inversion centre at the central copper Cu ( 1). The [Cu(dmg),12 -dianion bridges two copper ions through its deprotonated oxime oxygens with a Cu( 1 2) from the basal N 2 0 2 plane is very small [0.184(1) 8,] and the trinuclear skeleton is nearly coplanar.…”

“…X-Ray Structural Determination.-Single crystals of the complexes (1) and (4) suitable for X-ray crystallographic analysis were grown by slow diffusion. Crystal parameters and details of the data collection and refinements are given in Table 2.…”

Fluorescent vic-dioxime-type ligand and its mono- and dinuclear complexes: The preparation, spectroscopy, and electrochemistry of its various complexes

“…This behaviour was also observed with complexes 2 and 4, presumably due to negative charge transfer from ligand to metal during the formation of metal complexes. The redox chemistry of Ni(II) (2) and Co(II) (4) complexes exhibited both M(II)/M(III) and M(II)/M(I) redox couples. Figs.…”