Solvothermal and Reflux Syntheses, Crystal Structure and Properties of Lanthanide-Thiophenedicarboxylate-Based Metal-Organic Frameworks

Two new lanthanide thiophenedicarboxylatebased metal-organic frameworks with the formulas La-2(2,5-TDC)(3)(DMF)(2)H2O DMF (1) and Gd-2(2,5-TDC)(3)(DMF)(2) H2O (2) (2,5-TDC = 2,5-thiophenedicarboxylic acid; DMF = N,N'-dimethylformamide), have been synthesized by two different methods (solvothermal and reflux). The synthesis of these materials from metal nitrate hydrates with 2,5-TDC as the organic linker in DMF/n-propanol afforded two rigid non-interpenetrating frameworks with coordinated solvent molecules (DMF and H2O) occupying the channels. Compound (1) crystallizes in an orthorhombic space group Pna2(1) with Z = 4, a = 17.434(4) angstrom, b = 11.227(3) angstrom, c = 17.980(4) angstrom and V = 3,519.0(15) angstrom(3). Compound (2) crystallizes in a monoclinic P2(1)/n space group with Z = 4, a = 17.5387(17) angstrom, b = 10.8038(11) angstrom, c = 17.72 83(18) angstrom, beta = 104.793(2) and V = 3,247.9(6) angstrom(3). Powder X-ray diffraction, thermogravimetric analysis and infrared spectroscopy of (1) and (2) are presented.