Layered zinc 4-phosphonoisophthalates pillared by flexible bis(imidazole) Co-ligands

This paper reports two zinc phosphonates based on 4-phosphonoisophthalic acid (4-piH₄) and bis(imidazole) co-ligands, namely, [Zn ₂(4-pi)(1,2-bix)] (1) and [Zn₂(4-pi)(1,3-bix)] (2) (1,2-bix = 1,2-bis(imidazol-1-ylmethyl)benzene, 1,3-bix = 1,3-bis(imidazol-1- ylmethyl)benzene). Both show layer structures in which the inorganic tetranuclear cores of Zn₄P₂O₆ are connected by 4-pi^4-ligands. The 1,2-bix or 1,3-bix ligand binds to the Zn atoms within the tetranuclear unit or between the neighboring tetranuclear units in a cis-coordination mode, and fill in the interlayer spaces in both cases. The luminescent properties are investigated.