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, (C 6 H 7 N 2 O 2 + , HSO 4 − ) grown from aqueous solution were characterized by single crystal X-ray diffraction at 298 K. This compound crystallizes in P2 1 2 1 2 1 space group of orthorhombic system. The structure is built by chains formed by (NH 3 C 6 H 4 NO 2 + ) organic cations between which are situated the sulfate mineral anions (HSO 4 − ). The thermal analyses were realized by differential scanning calorimetry (DSC) technique which indicated that the p-Nitroanilinium sulfate present a reversible phase transition at T c = 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.