Growth and Investigation of the Nonlinear Optical Electrical and Antibacterial Properties of Organic Single Crystal: P‐Toluidinium p‐Toluenesulfonate

ABSTRACT

Single crystals of the organic nonlinear optical (NLO) material p‐Toluidinium p‐toluenesulfonate (PTPTSA) were grown from ethanol by the slow evaporation method at room temperature. The transparent, well‐faceted crystals indicate good optical quality. Single‐crystal X‐ray diffraction revealed that PTPTSA crystallizes in the monoclinic system with non‐centrosymmetric space group P2 ₁ . The crystalline nature was further confirmed by powder X‐ray diffraction analysis. FTIR spectroscopy identified the functional groups present in the crystal. UV‐Vis‐NIR studies were used to determine the absorption coefficient, optical bandgap, and refractive index, while photoluminescence analysis showed an emission peak at 570 nm. Photoconductivity measurements revealed negative photoconductive behavior. Dielectric studies, including dielectric constant, dielectric loss, and AC conductivity, were carried out as a function of frequency to evaluate the electrical properties of the crystal. Electronic polarizability was estimated using Penn's model and the Clausius–Mossotti equation. Third‐order nonlinear optical parameters were determined using the Z‐scan technique. Furthermore, for the first time, the PTPTSA crystal was evaluated against human pathogenic bacteria, namely Streptococcus aureus , Streptococcus pneumoniae , Klebsiella pneumoniae , and Escherichia coli .