Hydrothermal Synthesis, Crystal Structures, and Enantioselective Adsorption Property of Bis(L-histidinato) nickel(II) Monohydrate

Despite the numerous researches in metal-organic frameworks (MOFs), there are only few reports on biologically important amino acids, histidine in particular, on its use as bridging ligand in the construction of open-framework architectures. In this work, hydrothermal synthesis was used to prepare a compound based on Ni2+ and histidine. The coordination assembly of imidazole side chain of histidine with divalent nickel ions in aqueous condition yielded purple prismatic solids. Single crystal X-ray diffraction (XRD) analysis of the product revealed structure for Ni(C6H8N3O2)(2)center dot H2O that has a monoclinic (C2) structure with lattice parameters, a = 29.41, b = 8.27, c = 6.31 A, beta = 90.01 degrees. Circular dichroism-optical rotatory dispersion (CD-ORD), Powder X-ray diffraction (PXRD) and Fourier transform-infrared spectroscopy (FT-IR) analyses are conducted to further characterize the crystals. Enantioselective adsorption analysis using racemic mixture of 2-butanol confirmed bis(L-histidinato) nickel(II) monohydrate MOF crystal's enantioselective property preferentially favoring the adsorption of (S)-2-butanol isomer.