Three Co(II) metal–organic frameworks (Co-MOFs) build by 4,4′-bis(imidazolyl)diphenyl ether (bidpe), m-Phthalic acid (H 2 mpa), 5-Nitroisophthalic acid (H 2 nmpa) and 5-sulfonatobenzene-1,3-dicarboxylate (H 2 smpa), namely: Co(mpa)(bidpe) n ( 1 ), Co(nmpa)(bidpe) n ( 2 ), {Co 1.5 (smpa)(bidpe) 2 ·1.5H 2 O·0.25DMA} n ( 3 ), were synthesized under same solvothermal condition. The compounds have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, thermogravimetric (TG) analysis and powder X-ray diffraction (PXRD). The single-crystal X-ray diffraction analysis reveals that compound 1 shows a 4-connected sql net with Schläfli point symbol (4 4 ·6 2 ). Compound 2 displays a 3, 5-connected net with Schläfli point symbol (4 2 ·6 7 ·8)(4 2 ·6). Compound 3 possesses a 3-connected net with Schläfli point symbol (4 2 ·6). The photocatalytic investigations indicate that compounds 1 – 3 afford good photocatalytic capabilities in degradation of methylene blue (MB) and methylene violet (MV). Furthermore, the possible photocatalytic mechanisms have been discussed.