Growth, structural, vibrational, characterization and DFT investigations of 2-methylimidazolium hydrogen oxalate dihydrate (2MIO) single crystal-towards third order NLO applications

We report the studies conducted on the single crystal of 2-methyimidazolium hydrogen oxalate dihydrate (2MIO) which was achieved by employing the solution growth technique of conventional slow evapora-tion wherein the solvent used was deionized water. The confirmation of the grown 2MIO crystal's lattice parameters were accomplished by the analysis of single-crystal X-ray diffraction (SCXRD). The powder sample was utilized for the studies of identifying its crystalline phase, composition, and NLO efficiency. The UV-Vis-NIR studies show that the 2MIO crystal has a better transmittance in the region of entire visible and the lower cut-off wavelength is 280 nm. The decomposition and dissociation points of the 2MIO were studied by employing thermal measurements. The nonlinear optical parameters were com-puted for 2MIO from the performed Z-scan study. Additionally, quantum chemical studies were carried out on 2MIO molecule which was performed by making use of density functional theory (DFT) at the B3LYP/6-311 G (d.p) method. The optimized geometrical parameters, the bond length and bond angles were compared with the observed experimental XRD data. Hirshfeld surface analysis featuring 2D finger-print plots were analysed by using Crystal Explorer 3.1 such that it could confirm the intermolecular and weak interactions. Natural bond orbital (NBO) analysis was undertaken to evaluate the donor-accepter interactions and stabilization energies of the molecule. The HOMO-LUMO energy was analysed whereby the energy gap ( 4E ) and other related properties of the molecules present in 2MIO were calculated. The first-order hyperpolarizability of 2MIO was measured from the computational studies with which it is established that the obtained value is 4.95 times than that of standard urea.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, a single crystal of 2-methyimidazolium hydrogen oxalate dihydrate (2MIO) was successfully grown using the solution growth technique. The crystal's lattice parameters were determined by single-crystal X-ray diffraction analysis. The crystal was characterized for its crystalline phase, composition, and nonlinear optical efficiency. The results showed that the 2MIO crystal had good transmittance and a lower cut-off wavelength of 280 nm. Thermal measurements, Z-scan study, and quantum chemical calculations were performed to investigate the decomposition, nonlinear optical properties, and molecular characteristics of 2MIO. The computational studies revealed that the first-order hyperpolarizability of 2MIO was 4.95 times higher than that of standard urea.