Growth and characterisation of a new polymorph of barium maleate: A metal organic framework

• Metal co-ordination complexes of dicarboxylic acids have a wide range of potential applications.
• Single crystals of a new polymorph of barium maleate (BM) are grown by modified gel method.
• Two dimensional polymeric BM structure is stabilized by intermolecular hydrogen bonds.
• FT-IR studies and TGA/DTA studies are performed on the sample.
• The optical transparency of BM makes it attractive for optoelectronic applications.

A new polymorph of barium maleate (BM) with chemical formula C24H14O24Ba5⋅7H2O is grown by modified gel method. Transparent plate like crystals of dimensions 9 × 4 × 1 mm3 were obtained. Single crystal X-ray Diffraction analysis was done to determine the structure and the crystal belongs to triclinic system, P-1 space group with cell dimensions a = 7.2929(3) Å, b = 10.5454(4) Å, c = 14.2837(6) Å, α = 102.0350(10)°, β = 99.1580(10)°, γ = 102.9170(10)°. Hydrogen bonding stabilises the two dimensional polymeric crystal structure. Fourier Transform Infrared spectroscopic method was utilised for the analysis of various functional groups present in the complex. Elemental analysis confirmed the stoichiometry of the complex. Thermal properties of the crystal were studied by TGA/DTA. The material melts at 368 °C. The optical transparency of the crystal was studied using UV–Visible absorption spectra. The optical band gap is found to be 3.35 eV.

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