Synthesis, characterization and determination of standard molar enthalpies of formation of two copper borophosphates by solution calorimetry

Two pure microporous materials for copper borophosphates, Cu(H2O)2[B2P2O8(OH)2] and Cu3[B2P3O12(OH)3], have been synthesized and characterized by XRD, FTIR, simultaneous TG–DTA and chemical analysis. The molar enthalpies of solution of Cu(H2O)2[B2P2O8(OH)2] (s) and Cu3[B2P3O12(OH)3] (s) in 3 mol dm−3 HCl (aq) were measured, respectively. The molar enthalpies of solution of CuCl2·2H2O (s) in the mixture solvent of (HCl + H3BO3) (aq), and of H3PO4 (s) in the mixture solvent of (HCl + H3BO3 + CuCl2·2H2O) (aq) were also measured. With the incorporation of the previously determined enthalpy of solution of H3BO3 (s) in 3 mol dm−3 HCl (aq), together with the standard molar enthalpies of formation for H3PO4 (s), CuCl2·2H2O (s), H3BO3 (s), HCl (aq) and H2O (l), the standard molar enthalpies of formation of −(4078.8 ± 1.7) kJ mol−1 for Cu(H2O)2[B2P2O8(OH)2] (s) and −(4805.7 ± 2.0) kJ mol−1 for Cu3[B2P3O12(OH)3] (s) at 298.15 K were obtained on the basis of the appropriate thermochemical cycles.