Novel Azole-Benzene derived single crystal: Insights on growth and characterization, structural, mechanical, optical and NLO properties with reverse saturable absorption

The successful growth of 2-Methylbenzimidazolium 4-nitrobenzoate 4-nitrobenzoic acid (MINB) from a solution of ethyl and methyl alcohol using the solvent evaporation solution technique (SEST). The MINB crystal belongs to the triclinic crystal system and possesses a centrosymmetric P-1 space group, maintained by N–H…O and O–H…O interactions. Proton configuration confirmation was achieved through 1H-NMR analysis, while FTIR and Raman studies identified functional groups and vibrational frequencies. Optical transmission analysis revealed exceptional transparency (> 90%), along with a cut-off wavelength at 400 nm and E g = 2.91 eV. The crystal’s thermal behaviour was studied using thermogravimetric and differential thermal analysis, etching studies assessed crystal perfection, Vicker’s microhardness test determined load-dependent hardness, and dielectric properties (ε′, δ) were measured at 313 K with the frequency range of 50 Hz to 5 MHz. Nonlinear optical characteristics were explored using Q-switched Nd:YAG laser with a wavelength of 532 nm, exhibits Reverse saturable absorption (RSA) has been triggered by Two-Photon Absorption (2PA). The nonlinear absorption coefficient (β) of MINB crystal increased with concentration of solution, while the optical limiting threshold decreased with higher MINB concentrations, showcasing its intriguing properties and potential applications. We exploited First-principles density functional theory and ab-initio molecular dynamics simulations to investigate the electrical and optical characteristics of the MINB material. We establish that this material exhibits semiconductor properties, characterized by an energy band gap of 2.86 eV and notable absorption in the Ultraviolet (UV) light spectrum. Graphical abstract