Poly[di-aqua-[μ(2)-1,4-bis-(pyridin-3-ylmeth-yl)piperazine][μ(2)-4-(2-carboxyl-atoeth-yl)benzoato]cobalt(II)].

A layered cobalt coordination polymer containing both 4-(2-carboxyl-atoeth-yl)benzoate (ceb) and 1,4-bis-(3-pyridyl-meth-yl)piperazine (3-bpmp) ligands, [Co(C(10)H(8)O(4))(C(16)H(20)N(4))(H(2)O)(2)] (n) or [Co(ceb)(3-bpmp)(H(2)O)(2)] (n) , was isolated and structurally characterized by single-crystal X-ray diffraction. Chain-like [Co(ceb)(H(2)O)(2)] (n) units are oriented parallel to [101]. These are connected into (4,4)-grid coordination polymer layers by tethering 3-bpmp ligands. The layer motifs stack in an AAA pattern mediated by O-H⋯N hydrogen-bonding inter-actions between the aqua ligands in one layer and 3-bpmp piperazinyl N atoms in the abutting layer.