Hydrothermal reactions of CdCl2·2.5H2O with 3,6-bis(imidazol-1-yl)carbazole (bmcz), 2-amine-1,4-benzenedicarboxylic acid (2-NH2-1,4-H2BDC) or 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) afforded two coordination polymers, [Cd(2-NH2-1,4-BDC)(bmcz)]n (1) and [Cd(1,4-NDC)(bmcz)]n (2). Complexes 1 and 2 were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. 1 and 2 are isomorphic and exhibit 3D supermolecular structures. The solid state luminescent and optical properties of 1 and 2 at ambient temperature were also investigated. A comparative study on their photocatalytic activity toward the degradation of methylene blue in polluted water was explored.