Reversible phase transition in semi-organic compound p-Nitroanilinium sulfate detected using second harmonic generation as a tool

Abstract Crystals structure of p-Nitroanilinium sulfate, (C6H7N2O2+, HSO4−) grown from aqueous solution were characterized by single crystal X-ray diffraction at 298 K. This compound crystallizes in P212121 space group of orthorhombic system. The structure is built by chains formed by (NH3C6H4NO2+) organic cations between which are situated the sulfate mineral anions (HSO4−). The thermal analyses were realized by differential scanning calorimetry (DSC) technique which indicated that the p-Nitroanilinium sulfate present a reversible phase transition at Tc = 338(2) K. The SHG measurements were realized at room temperature as well as with temperature depending. During heating and cooling processes the second harmonic signals show a reversible phase transition at 57 °C. These results are in good agreement with the results obtained from DSC measurements.