In the present study, two new Co(II)-based coordination polymers (CPs) with chemical formulas of {[Co₃(μ₃-OH)(L)(H₂O)₃]·2H₂O}_n (1) and {[Co₃(μ₃-OH)(L)(H₂O)]·2DMF·3H₂O}_n (2) have been successfully prepared by the reaction of Co(NO₃)₂·6H₂O with π-electron-rich polycarboxylate aryl ether ligand 5,5΄-((5-carboxy-1,3-phenylene)bis(oxy))diisophthalic acid (H₅L) under different solvothermal reaction conditions. Both CPs have been studied via single-crystal X-day diffraction, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The photophysical studies indicated that complex 2 with good water stability is a potential semiconductive material, which could be applied for the degradation of methylene blue (MB) under UV light irradiation and exhibit good stability and recyclability.