Hydrothermal synthesis has afforded a 3D copper(II) metal–organic framework (MOF) based on a new rigid bis(triazole)-based ligand, namely, {[Cu 3 (btb) 3 (nbta) 2 ]·(H 2 O) 2 } n (btb=4,4′-bis(1,2,4-triazolyl-1-yl)-biphenyl, H 3 nbta=5-nitro-1,2,3-benzenetricarboxylic acid), which has been characterized by IR, elemental analysis, thermal gravimetric and single-crystal X-ray diffraction. The structural analyses reveal that title complex displays a rarely 3D trinodal (3,4,4)-connected network with 3,4,4T20 topology. Further, fluorescence and excellent adsorption properties for congo red dye of the compound have been investigated.