Abstract
Three compounds, [Cu(Pic)(2)(H2O)] (la), [M(Pic)(2)(H2O)(2)]center dot 2H(2)O] (M=Co (2a), Zn (3a), Pic = 2-picolinic acid) were obtained by solvent-free synthesis through grinding of metal acetate salt with 2-picolinic acid. Favorable comparison of solvent-free with solution based method of lb, 2b and 3b was observed. Good resemblance of identity of compounds obtained through the two methods was confirmed by elemental analysis, spectroscopic techniques (UV-Vis and FTIR), TGA and PXRD. The single crystal diffraction data for [Co(Pic)(2)(H2O)(2)]center dot 2H(2)O obtained from the Cambridge structure database (CSD), its PXRD simulated patterns closely matched that of complex 2a by solvent-free synthesis. Vapochromic behavior of this complex was studied using colour change, FT-IR, TGA, PXRD and solid state UV-visible spectroscopies. This complex generated specific colour which is also evident in the shifting of the vibrational frequencies (nu O-H and nu C=O bands). The resulting inclusion compounds have different colours depending on the solvent used. In addition, exposure of the resultant inclusion compounds to ambient environment or heating for a few minutes regenerate the original material without degradation even after exposure/heating cycles as evident from TGA/DTG thermograms. (C) 2017 Elsevier Masson SAS. All rights reserved.