Two 3D complexes with tetranuclear clusters Co4(CO2)8(μ2-H2O)2 and Co4(μ3-OH)26+ were obtain under hydrothermal conditions, as n-type semiconductors, which have catalytic activity for the degradation of Rhodamine B. Display omitted Complexes {Co2(DTA)2(1,4-BMIB)(H2O)·1·.5H2O}n(ZNC-9) and {Co2 (DTA)1.5(OH)(TIB)·5H2O}n (ZNC-10) (H2DTA = 2,5-dimethoxyterephthalic acid, 1,4-BMIB = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene, TIB = 1,3,5-tri(1H- imidazol-1-yl)benzene) were obtained via hydrothermal reaction condition. DTA2− ligands adopted various coordination modes to result in tetranuclear clusters Co4(CO2)8(μ2-H2O)2 and Co4(μ3-OH)26+ in ZNC-9 and ZNC-10, respectively. In complex ZNC-9, Co4(CO2)8(μ2-H2O)2 as 10-connected node was bridged by DTA2− and 1,4-BMIB to form a 3D framework with Schlafli symbol of (36.434.62). In complex ZNC-10, DTA2− ligands and Co4(μ3-OH)22+ built a 4-connected dia net, while TIB and Co4(μ3-OH)2 units built a 3,6-connected ant net. The dia and ant nets further constructed a (3,10)-connected framework with point symbol (3.42)2(34.410.512.613.76). Additionally, UV–vis spectra and electrochemical tests have confirmed that ZNC-9 and ZNC-10 belong to n-type semiconductors possessing low resistance for charge transportation. In photo-catalytic experiments, ZNC-9 and ZNC-10 have obvious catalytic activity in degradation of dye under ultraviolet light.