The electrochemical properties, nitrogen adsorption, and photocatalytic activities of three 3D metal-organic frameworks bearing the rigid terphenyl tetracarboxylates ligands

Three new three-dimensional (3D) metal-organic frameworks (MOFs) derived from terphenyl tetracarboxylates, namely, [Mn(H2L)](n) (1), {[Ni-3(L)(mu(3)-OH)(2)(H2O)(4)](2)center dot 3H(2)O}(n) (2) and {[(CH3)(2)NH2](2)[Zn(L)]center dot 2DMF}(n) (3) (H4L = [1,1':4',1 ''-terphenyl]-2',4,4 '',5'-tetracarboxylic acid), were synthesized and characterized by elemental analyses, IR spectra, thermogravimetric (TG) analyses, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. Complex 1 represents a 6-connected {4(12).6(3)} framework, which contains 1D stair-type chain and 2D layer. Complex 2 displays the complicated {4(11).6(12).8(5)}{4(2).6}{4(3).6(3)}{4(3)}{4(4).6(2)}{4(8).6(6).8} topology, in which Ni-O chains play an important role in the whole framework. In complex 3, the wave-like and H-like 1D chains link each other to create the 3D architecture with {4(2).8(4)} topology. The introduction of different metal ions and the diversities synthesis processes lead to the great differences of the final 3D frameworks. In addition, the fluorescence properties reveal that complex 3 containing Zn-II possesses a fluorescent intensity, and complexes 1-2 based on Mn-II and Ni-II have no florescent activity. The electrochemical properties show that complex 2 possesses electrocatalytic activity for the reduction of nitrite. Photocatalytic properties indicate that complex 1 has good catalytic activity for the degradation of methylene blue (MB). Nitrogen adsorption reveals that complex 3 has adsorption property for nitrogen at 77 K.