Via solvothermal synthesis, the self-assembly of CuCl(2), 1,3,5-benzenetricarboxylic acid, and N,N'-bis(4-pyridylformamide)-1,4-benzene in DMF generated a novel coordination polymer containing an unprecedented (3,4)-connected network; 3-fold interpenetration and considerable solvent-accessible cavities occupied by reversible guest water molecules were also observed.