Preparation and characterization ofL-tartaric acid–silica composites recognizing molecular asymmetry

Abstract

l-Tartaric acid–silica composites have been prepared by the sol–gel method in which tetraethoxysilane is hydrolysed after reacting with l-tartaric acid. Optical resolution of tris(pentane-2,4-dionato)metal complexes was performed using sol–gel derived composites and composites prepared using a conventional impregnation technique. The composites prepared through the sol–gel process showed much higher optical resolution abilities when the composite was used for packing in chromatography. X-Ray diffraction and NMR results suggested that l-tartaric acid in the sol–gel derived composites is highly dispersed because it bonds to silicon atoms. The silica gel support was observed by scanning electron microscopy to be composed of small particles whose diameters are below 30 nm. The asymmetry recognition ability of the composites was found to arise from the combined effect of the silica support and the highly dispersed optically active compound.