Exploring the structural and optical characteristics of the charge transfer complex 2,3-dimethylquinoxaliniumpicrate: a comprehensive investigation through experimental and computational approaches

In the present study, we employed a slow evaporation solution growth technique to cultivate a organic single crystals of 2,3-dimethylquinoxalinum picrate (MQPA) at room temperature. By subjecting the crystal to single crystal X-ray diffraction analysis, we uncovered its structural features. It was crystallized into monoclinic crystal system, characterized by the centrosymmetric P2₁/c space group. A careful examination of the supramolecular features and structural characteristics showed strong (N–H⁺….O⁻) non-covalent interactions that play a key role in the crystal packing. Our investigation encompassed the identification of the chemical structure and functional groups through spectral analyses. We delved into the optical attributes of MQPA via spectral analyses of UV–Vis-NIR and photoluminescence measurements. Additionally, the thermal stability of the resulting crystal was assessed using TG-DSC analysis. Employing the Z-scan method, we quantified nonlinear absorption (β), non-linear refractive index (n₂), and the third-order nonlinear susceptibility (χ³). To refine our understanding of the stability and properties of MQPA, we conducted quantum chemical calculations, optimizing geometry and examining electrostatic potential, natural population, and FMO analyses. In our quest to delve deeper into the crystal structural stability, we harnessed fingerprint plots and Hirshfeld surface analyses to evaluate the intermolecular interactions at play. The findings suggest that the grown materials could be suitable for optical and optoelectronic applications.