Organic single crystals of β-anilinium 4-hydroxybenzenesulfonate (BA4BS) were grown at room temperature using the slow evaporation solution technique. Single-crystal X-ray diffraction (SCXRD) confirmed that BA4BS crystallizes in a centrosymmetric monoclinic P2₁/c space group, while powder X-ray diffraction (PXRD) results matched well with the simulated CIF pattern, confirming phase purity. Fourier transform infrared (FTIR) spectroscopy was used to analyse the vibrational behaviour, and UV–Visible spectroscopy revealed an optical band gap of 3.819 eV. The thermal durability threshold of BA4BS crystal was determined to be 151 °C, and successive thermal degradation temperatures were examined using thermogravimetric and differential thermal analysis (TG–DTA). Photoconductivity studies revealed negative photoconductive behaviour, and dielectric constant (ε′) and loss (tan δ) measurements were performed over a range of frequencies at room temperature to evaluate the electrical properties. Charge transfer pathways were examined via HOMO–LUMO analysis, and Hirshfeld surface mapping visualized the spatial distribution of intermolecular interactions. Topological investigations were conducted to elucidate the electronic structure and intermolecular interactions within the material. Open and closed aperture Z-scan studies revealed self-defocusing and reverse saturable absorption, yielding third-order NLO parameters with <InlineEquation ID="IEq1"> <EquationSource Format="TEX">${\chi }^{\left(3\right)}=2.555\times {10}^{-6}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mrow> <mi>χ</mi> </mrow> <mfenced close=")" open="("> <mn>3</mn> </mfenced> </msup> <mo>=</mo> <mn>2.555</mn> <mo>×</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>-</mo> <mn>6</mn> </mrow> </msup> </mrow> </math></EquationSource> </InlineEquation> esu. The combination of favourable optical properties, thermal stability, and pronounced nonlinear <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${\chi }^{\left(3\right)}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi>χ</mi> </mrow> <mfenced close=")" open="("> <mn>3</mn> </mfenced> </msup> </math></EquationSource> </InlineEquation> response establishes BA4BS as a viable material with potential applications in optical limiting, photonic switching, and frequency conversion systems.

Growth and characterization of β-anilinium 4-hydroxybenzenesulfonate single crystals for promising optical applications

期刊论文
发表日期：

2026年1月23日

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S. P. Sunwathi,
S. Tamilarasi,
B. Sahaya Infant Lasalle,
Kalpana Sukumar,
Muthu Senthil Pandian,
J. Janczak,
N. Kanagathara

摘要

Organic single crystals of β-anilinium 4-hydroxybenzenesulfonate (BA4BS) were grown at room temperature using the slow evaporation solution technique. Single-crystal X-ray diffraction (SCXRD) confirmed that BA4BS crystallizes in a centrosymmetric monoclinic P2₁/c space group, while powder X-ray diffraction (PXRD) results matched well with the simulated CIF pattern, confirming phase purity. Fourier transform infrared (FTIR) spectroscopy was used to analyse the vibrational behaviour, and UV–Visible spectroscopy revealed an optical band gap of 3.819 eV. The thermal durability threshold of BA4BS crystal was determined to be 151 °C, and successive thermal degradation temperatures were examined using thermogravimetric and differential thermal analysis (TG–DTA). Photoconductivity studies revealed negative photoconductive behaviour, and dielectric constant (ε′) and loss (tan δ) measurements were performed over a range of frequencies at room temperature to evaluate the electrical properties. Charge transfer pathways were examined via HOMO–LUMO analysis, and Hirshfeld surface mapping visualized the spatial distribution of intermolecular interactions. Topological investigations were conducted to elucidate the electronic structure and intermolecular interactions within the material. Open and closed aperture Z-scan studies revealed self-defocusing and reverse saturable absorption, yielding third-order NLO parameters with ${\chi }^{\left(3\right)}=2.555\times {10}^{-6}$ $χ^{(3)} = 2.555 \times 10^{- 6}$ esu. The combination of favourable optical properties, thermal stability, and pronounced nonlinear ${\chi }^{\left(3\right)}$ $χ^{(3)}$ response establishes BA4BS as a viable material with potential applications in optical limiting, photonic switching, and frequency conversion systems.