Two Polymorphs of an Organic-Zincophosphate Incorporating a Terephthalate Bridging Ligand in an Unusual Bonding Mode

Two new polymorphs of a zinc phosphate incorporating the terephthalate organic ligand 1,4-benzenedicarboxylate (BDC), (H₂DA)Zn₂(cis-BDC)(HPO₄)₂ (1) and (H₂DA)Zn₂(trans-BDC)(HPO₄)₂ (2), where DA = 1,7-diaminoheptane, were synthesized via a hydro(solvo)thermal method at different reaction temperatures and structurally characterized by single-crystal X-ray diffraction. Interestingly, the BDC ligands, which adopt the bis-monodentate coordination model with a unusual cis type for compound 1 and with a trans linkage for compound 2, bridge the Zn atoms of the inorganic layers in the generation of two polymorphs with structural diversities (one kind of arrangement of the layered zincophosphate layer in 1; the flat and zigzag sheets of inorganic networks in 2). A simple method for tuning the optical luminescence of the title compound from blue, red, green, yellow, and pink to white emission by stirring powdered samples in lanthanide-cation-containing aqueous ethanol solutions at room temperature for 1-2 h is also presented.