catena-Poly[[[tetra-aqua-zinc(II)]-μ-1,4-bis-(1,2,4-triazol-1-yl)butane-κN:N] biphenyl-4,4'-dicarboxyl-ate].

The asymmetric unit of the polymeric title compound, {[Zn(C(8)H(12)N(6))(H(2)O)(4)](C(14)H(8)O(4))}(n) or {[Zn(BTB)(H(2)O)(4)](BPDC)}(n) [BTB is 1,4-bis-(1,2,4-triazol-1-yl)butane and H(2)BPDC is biphenyl-4,4'-dicarb-oxy-lic acid], contains half a [Zn(BTB)(H(2)O)(4)](2+) cation and half a BPDC anion, both ions lying about a crystallographic inversion centre. The crystal structure consists of zigzag polymeric cationic chains parallel to the c axis and uncoordinated anions linked into a three-dimensional supra-molecular architecture by O-H⋯O, C-H⋯O hydrogen bonds and C-H⋯π inter-actions.