While N,N-bis(4-pyridyl)urea affords a 5-fold interpenetrated diamondoid network, its positional isomer N,N-bis(3-pyridyl)urea gave a net-to-net hydrogen-bonded (4,4) net (square grid network) displaying temperature-dependent anion-induced reversible single-crystal-to-single-crystal disorder-order phase transition, when the ligands are reacted with zinc perchlorate.