Two novel 3D metal-organic frameworks based on two tetrahedral ligands: syntheses, structures, photoluminescence and photocatalytic properties

Two novel metal-organic frameworks (MOFs), namely [Co-2(L1)(L2)]center dot 4.25H(2)O (1) and [Cd-4(L1)(2)(L2)(2)]center dot 4H(2)O center dot DMF (2) (H(4)L1 = tetrakis[4-(carboxyphenyl)-oxamethyl]methane acid and L2 = tetrakis(imidazol-1-ylmethyl)methane), have been hydrothermally synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses, UV-vis absorption spectra, optical energy gap and emission spectra. In 1, tetrahedral L1 and L2 ligands link neighboring Co(II) atoms to generate a unique 3D self-penetrating framework with a tetranodal 4-connected (6.8(5))(2)(6(3).8(3))(8(6)) topology. However, in 2, Cd(II) atoms are bridged by L1 and L2 ligands to furnish a 3D framework with a highly rare (4,8)-connected (4(6))(4(4).6(2))(4(10).6(14).7(4)) topology. In addition, compound 1 exhibits photocatalytic activity for dye degradation under UV light or visible-light and shows good stability toward photocatalysis.