Synthesis and structure of an open-framework cobalt zincophosphate

Abstract

Introducing cobalt into a Zn–P–O–amine system and using oxalates as starting materials, an amine containing open-framework cobalt zincophosphate, [C₄N₂H₁₂][Co_0.14Zn_1.86(PO₄)(H_1.5PO₄)₂] (1), has been hydrothermally synthesized and structurally determined. It crystallizes in the monoclinic space group C2/c (No. 15) with cell parameters a = 13.374(3) Å, b = 12.827(3) Å, c = 8.1940(16) Å, β = 94.77(3)°, V = 1400.9(5) ų, Z = 4, D_cal = 2.399 g cm⁻³. The linkages of ZnO₄ and PO₄ give rise to four-membered rings, which serve as the secondary building unit for compound 1. The four-membered rings (four-MR) share their corners leading to chains. Connection of these chains results in a complex three-dimensional channel system. Eight-MR, twelve-MR and highly distorted twelve-MR channels can be observed along the [010], [110] and [101] directions, respectively. The prominent feature of compound 1 is the clover-like 16-MR channel along the [001] direction. The channel spaces are occupied by the diprotonated piperazine molecules with H-bonds to the framework.