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-mont morillonite carried out under different dynamic conditions such as ultrason ic irradiation, refluxing, autoclaving, and vigorous stirring showed that u nder ultrasonic irradiation, maximum adsorption of the metal complexes occu rred within a period of 30 min. Metal complexes containing the phen ligand showed higher adsorption than those containing bpy. Maximum adsorption up t o about three times the cation exchange capacity (CEC) of the clay was obse rved. Aggregated (basal spacing door 12.5 Angstrom) Na-montmorillonite, in treatment with a higher amount (> CEC) of metal complexes, formed monolayer ed (basal spacing d(001) 17.6 Angstrom) species, while with predispersed cl ay, bilayered (basal spacing d(001) > 28 Angstrom) or pseudo-trilayer (basa l spacing d(001) > 32 Angstrom) species were formed. The bilayered species were thermally stable up to 250 degreesC and above this temperature monolay ered species were formed. The thermal stability of the intersalated species was higher than that of the intercalated ones. X-ray diffraction, UV-visib le, IR-spectroscopy, thermal analyses, and surface area measurements were u sed for characterization of the products. (C) 2001 Academic Press.