Thermal and spectroscopic studies on the decomposition of [Ni{di(2-aminoethyl)amine}2]- and [Ni(2,2′:6′,2"-terpyridine)2]-Montmorillonite intercalated composites

Intercalated [Ni{di(2-aminoethyl)amine}(2)]-Montmorillonite (I) and [Ni(2,2':6',2 "-terpyridine)(2)]-Montmorillonite (II) composites have been synthesized and their thermal behavior studied by TG, DTG and DTA substantiated by XRD and IR spectroscopy. Thermal stabilities of the composites I and II were about 50 and 150 degrees C higher, respectively, compared to their respective free metal complex salts. These results indicate that the metal complex with aromatic backboned ligands had higher thermal stability than that of the aliphatic one upon intercalation into layered clay. XRD data showed that on heating, the basal spacing (d(001)) of the I composite decreased gradually from 14.5 Angstrom at 50 degrees C to about 13.5 Angstrom at 250 degrees C which may correspond with the transformation to a distorted octahedral metal complex in the interlamellar spacing of the clay. On the other hand, the II composite showed a basal spacing (d(001)) of about 19.4 Angstrom at 50 degrees C, which decreased slightly to 19.0 Angstrom at about 350 degrees C indicating the presence of intercalated octahedral metal complex and thus corroborates the thermal analyses. IR spectra show characteristic bands of I and II composites up to about 250 and 350 degrees C, respectively, which also support the data of thermal as well as XRD analyses. Such metal-complex-clay composites may be utilized for developing microporous layered materials exhibiting comparatively higher thermal stability. (C) 2000 Elsevier Science B.V. All rights reserved.