An organic 8-hydroxyquinolinium 4-chloro-3-nitrobenzoate 4-chloro-3-nitrobenzoic acid (8-HQCN) was synthesized and the crystals were grown by employing solution growth method. Single crystal XRD data revealed crystal system (monoclinic, space group P21/n), and cell dimensions (a = 6.9806(2) Å, b = 11.9919(4) Å, c = 26.8872(8) Å). The FT-IR, FT-Raman and NMR spectral analyses provide the molecular structure. UV-visible spectrum provides a band gap (3.03 eV) and cut off wavelength (404 nm) of the crystal. The broad emission at 580 nm in PL spectrum reveals the suitability of the material yellow light emission. Vicker's microhardness study gives the mechanical stability of the grown crystal. The nonlinear optical susceptibility (χ(3)) of the molecule was calculated as 16.78 × 10-6 esu from Z- scan technique and from DFT theory it was calculated to be 5.632 × 10-6esu using cam-b3lyp/6-311G (d, p). Thermo-optic coefficient of 8-HQCN was predicted to be 3.805 × 10-6 K-1 by thermal conductivity studies. This thermally prompted defocusing character can be made useful in optical limiters. The thermal investigation exhibits the bearing proficiency of 8-HQCN to be 127 °C. The orbital energy, band gap and the second hyperpolarizability were also studied by varying the applied field. The dispersion of the dielectric constant illustrates the usual behavior and the enhanced quality of the material gives the low dielectric loss. Antibacterial studies were taken to check the resistance to harmful bacteria of the grown crystal. © 2020 IOP Publishing Ltd.