Effect of crystallization conditions on the composition and structure of {ZnCa} metal-organic coordination polymers with isophthalate anions

The reaction of the heterometallic complex [Zn₂Ca(piv)₆(py)₂] (piv is pivalate anion, py is pyridine) with isophthalic acid (1,3-H₂bdc) under the solvothermal conditions afforded a series of new {ZnCa} coordination polymers [Zn₂Ca(DMF)₂(1,3-bdc)₃]_n • •n(DMF) (1), [Zn₃Ca₃(H₂O)₅(DMF)(1,3-bdc)₆]_n • 3n(C₆H₆) • 3n(DMF) (2), and [Zn₄Ca₃(H₂O)₄(NMP)(1,3-bdc)₈]_n (3, NMP is N-methylpyrrolidone). The structures of the new compounds were determined by single-crystal X-ray diffraction. Depending on the conditions of the synthesis and crystallization, porous coordination polymers with different structures and composition were obtained. The use of poorly soluble zinc iso-phthalate as one of the starting compounds in the reaction with calcium nitrate enabled the preparation of single-phase complex 1 in amounts required for further investigations. The synthesized compounds were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, and elemental analysis.