Synthesis, characterization and thermal behavior of tetrakis(melamine2+) bis(melamine+) pentakis(monohydrogenphosphate) tetrahydrate

•A new Tetrakis(M2+)Bis(M+)Pentakis(hydrogenphosphate)Tetrahydrate was synthesized.•The title compound was characterized by SXRD,UV–vis, FTIR, NMR and TGA-DTA studies.•It crystallizes in monoclinic crystal system and the space group is P 21.•The protonation of triazine caused dramatic changes in the frequencies of the ring.•The new material has more thermal stability up to 200 °c.

A new organic–inorganic salt, tetrakis (2,4,6-triamino-1,3,5-triazin-1,3-diium) bis (2,4,6-triamino-1,3,5-triazin-1-ium) pentakis (monohydrogenphosphate) tetrahydrate, 4C3H8N6+2. 2C3H7N6+. 5HPO42−. 4H2O was synthesized through the reaction of melamine and phosphoric acid in an acidic medium HCl/H2O. It was then characterized by X-ray diffraction. The title compound crystallizes in monoclinic system with non-centrosymetric space group P 21 with lattice parameters a = 11.3008 Å, b = 20.9798 Å, c = 12.2679 Å, α = 90°, β = 117.236°, γ = 90°, Z = 2 and V = 2586.10 (Å)3. The UV–vis absorption spectrum UV–vis showed that the crystal has a good optical transmittance in the entire visible region with a lower cut off wavelength of 290 nm. The vibrational frequencies of various functional groups present in the crystal were identified by FT-IR analysis. The chemical structure of the compound was also confirmed by 1H, 13C and 31P NMR spectroscopy. TGA-DTA analysis revealed that the materials have a good thermal stability without any melting.

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