Four Co(II) - MOFs based on 3,3′-azodibenzoic acid ligand: Syntheses, crystal structure, photodegradation properties

Four novel Co(II)-MOFs based on the 3,3′-azodibenzoic acid (H2L), namely [CoL (bimb)0.5]n (1), {[CoL (bimmb)]·DMF}n (2), [CoL (bimmb)0.5]n (3), and [CoL (bbibp)]n (4) (bimb = 1,4-bisimidazole, bimmb = 4-bis(imidazole-1-ylmethyl)benzene, bbibp = 4,4′-bis(benzoimidazo-1-yl)biphenyl and DMF = N, N′-dimethylformamide) have been synthesized under solvothermal conditions and characterized by elemental analysis, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis and single crystal X-ray diffraction. Single crystal X-ray diffraction analysis shows that complex 1 and complex 3 possesses the same structure as uninodal 6-connected 3D (three-dimensional) pcu topology framework with the point symbol (412.63), whereas complex 2 possesses an uninodal 3-connected hcb topology framework with the point symbol (63) and complex 4 displays a 4-connected sql topology framework with the point symbol of (44.62). In addition, the photocatalytic degradation properties of the four complexes have been investigated. Significantly, complex 4 is the best photocatalyst for the degradation of three organic dyes (MV/MB/RhB). Complex 2 is the good photocatalyst for the degradation of two organic dyes (RhB/MB). Complex 3 is the good photocatalyst for the degradation of two organic dyes (MV/MB) and complex 1 is the good photocatalyst for the degradation of only one organic dyes (MV).