Intersalation reactions of trisdiimine metal complexes with montmorillonite clay: A new approach

Intersalation reactions of the complexes [Ni(L-L)(3)]SO4 and [Ni(L-L)(3)]Cl-2 (L-L = 1,10-phenanthroline (phen), 2,2 ' -bipyridyl (bpy)), with Na-montmorillonite carried out under different dynamic conditions such as ultrasonic irradiation, refluxing, autoclaving, and vigorous stirring showed that under ultrasonic irradiation, maximum adsorption of the metal complexes occurred within a period of 30 min. Metal complexes containing the phen ligand showed higher adsorption than those containing bpy. Maximum adsorption up to about three times the cation exchange capacity (CEC) of the clay was observed. Aggregated (basal spacing door 12.5 Angstrom) Na-montmorillonite, in treatment with a higher amount (> CEC) of metal complexes, formed monolayered (basal spacing d(001) 17.6 Angstrom) species, while with predispersed clay, bilayered (basal spacing d(001) > 28 Angstrom) or pseudo-trilayer (basal spacing d(001) > 32 Angstrom) species were formed. The bilayered species were thermally stable up to 250 degreesC and above this temperature monolayered species were formed. The thermal stability of the intersalated species was higher than that of the intercalated ones. X-ray diffraction, UV-visible, IR-spectroscopy, thermal analyses, and surface area measurements were used for characterization of the products. (C) 2001 Academic Press.