Novel open-framework architecture in strontium(II) phosphonate

Hydrothermal reaction of strontium nitrate with N,N′-piperazine-bis(methylenephosphonic acid) (H4L) afforded a novel three-dimensional strontium(II) diphosphonate, namely, [Sr(H2L)(H2O)2] · 3H2O (1). The structure of compound 1 can be viewed as a pillar-layered architecture in which 1D chains of [Sr(PO3)] along a-axes are further crosslinked by the piperazine bismethylene spacers along b- and c-axes.