New Organic Acidic Cyclohexaphosphate: Synthesis, Crystal Structure, Physicochemical Study, and In Vitro Biochemical Investigation

Abstract

A novel organic cyclohexaphosphate [o-(OCH3)C6H4NH3]4H2P6O18·4H2O (1) has been synthesised by the slow evaporation method. An X-ray diffraction study on a single crystal was used to identify this compound. It shows that this acidic cyclohexaphosphate crystallizes in the monoclinic space group P21/n with V 2215.1(1) Å3 and Z 2. Its crystal structure is a packing of alternating inorganic and organic layers parallel to the (a, c) planes. Crystal symmetry is confirmed by 31P magic angle spinning-NMR spectroscopy. Furthermore, spectroscopic (IR, UV-visible) and thermal (thermogravimetric/differential thermal analysis and differential scanning calorimetry) characteristics are given. The excitation and emission spectra were recorded showing blue photoluminescence. The alternating current conductivity and dielectric measurements were carried out in the temperature range 333–403 K and the frequency range from 5 Hz to 13 MHz. The impedance data were well fitted to an equivalent electrical circuit. The temperature dependence of the direct current conductivity follows the Arrhenius law and the frequency dependence of σAC(ω,T) follows Jonscher’s universal law. Antioxidant properties of this compound were studied, in vitro, at various concentrations with different tests; 1,1-diphenyl-2-picrylhydrazyl, hydroxyl scavenging ability, ferric reducing power, and ferrous ion chelating ability, using ascorbic acid as control.