Spectroscopic, thermal and structural studies on manganous malate crystals
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TRUCTURE OF ORGANIC COMPOUNDS
Spectroscopic, Thermal and Structural Studies on Manganous Malate Crystals1 J. Thomas, A. Lincy, V. Mahalakshmi, and K. V. Saban Smart Materials Analytic Research and Technology (SMART), Department of Physics, St. Berchmans College, Changanassery, Kerala, India email: [email protected]; [email protected] Received September 23, 2011
Abstract—Prismatic crystals of manganous malate have been prepared by controlled ionic diffusion in hydrosilica gel. The structure was elucidated using single crystal Xray diffraction. The crystals are orthor hombic with space group Pbca. Vibrations of the functional groups were identified by the FTIR spectrum. Thermogravimetric and differential thermal analyses (TG–DTA) were carried out to explore the thermal decomposition pattern of the material. Structural information derived from FTIR and TG–DTA studies is in conformity with the single crystal XRD data. DOI: 10.1134/S1063774513010276 1
INTRODUCTION
MATERIALS AND METHODS
In recent years, many crystals containing discrete molecules and infinite supramolecular networks, which show a variety of interesting properties, have been prepared from the coordination of transition metals and organic molecules [1–8]. The strength of the coordination bonds between the cation and the anionic or neutral organic molecules containing the functional groups like –CN, –COOH will be in between that of noncovalent interactions and carbon carbon bonds of majority of the organic compounds [9]. This structural feature enables many metal coordi nation complexes to find their niche among lumines cent materials, magnetic materials, porous or zeolitic materials and nonlinear optical materials [10–12]. Many metal carboxylates have been found crystalliz ing with molecular acentricity and this makes them potential candidates for the search for optical nonlin earity and second harmonic generation capability. Single crystals with faces having a few square millime tres area are required for the systematic evaluation of the nonlinear optical coefficients of that material. However, it is difficult to grow metal carboxylate crys tals with adequate size and quality required for such studies. Recently, we succeeded in growing good crys tals of a few metal coordinated complexes of malic and malonic acids [13–18]. This report presents the growth of manganous malate crystals of appreciable size. Its structure, vibrational spectrum and thermal decomposition pattern have also been discussed.
Single crystals of the title compound were prepared in straight tubes by the method of controlled diffusion in gel medium [19]. AR (analytical reagent) grade manganous chloride, Lmalic acid and sodium meta silicate nonahydrate (Na2SiO3 · 9H2O) were the reagents used. Hydrosilica gel of the desired pH was prepared, in test tubes, by titrating aqueous sodium metasilicate solution against malic acid. Ensuring proper gelation, supernatant MnCl2 was poured over it and kept undisturbed for slow diffusion of the ionic species to take place. A
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