Synthesis, structure, NBO, Hirshfeld surface, NMR, HOMO-LUMO, UV, photoluminescence, z scan, vibrational and thermal analysis of piperazinedi-ium tetrakis (μ2‑chloro)-diaqua-dichloro-di-cadmium single crystal

Abstract

Single crystals of Piperazinedi-ium tetrakis (μ2‑chloro)-diaqua-dichloro-di-cadmium(ii), a three-dimensional framework of chained chlorocadmate with the organic piperazine as a template, are synthesized by slow evaporation and confirmed by single-crystal X-ray diffraction. Theoretical analysis such as geometrical optimization, NBO, Hirshfeld surface, hyperpolarizability and Frontier molecular orbitals analyzes were performed using DFT calculations. The most stable molecular structure is optimized by DFT/ B3LYP method with the LAN2DZ basis set in the Gaussian 09 program package. The intra and intermolecular interactions and donor-acceptor energy relations are studied using the NBO 5.0 program. The analysis reveals that the strength of hydrogen-bonded intermolecular interaction is in the order NH…O> NH…Cl > CH…Cl. The NMR, UV-Visible, FTIR and FT-Raman spectra are recorded and analyzed for confirmation of electronic structure and intermolecular interactions. The simulated FTIR and FT-Raman spectra are matched with the experimental spectra. The vibrational wavenumbers are calculated and assigned on the basis of potential energy distribution using MOLVIB software. The hydrogen-bonded intermolecular interactions such as NH…Cl, OH…Cl, CH…Cl and charge delocalization give stability to the dimer structure. The 2D fingerprint maps revealed that the highest share of total Hirshfeld surface is attributed to H….Cl/Cl…H interactions with 62.5%. The charge transfer from the metal atom to the amine group and the low HOMO-LUMO energy gap (3.8469 eV) enhance the NLO activity of the molecule. The open and closed aperture Z-scan technique revealed that the title compound has the highest nonlinear absorption coefficient value β(4.118 × 10−4 m/W) with a greater third-order nonlinear optical response than the five other optical limiters we have studied. TGA and DTA reveal the suitability of the crystal for NLO and other laser applications up to 92.37 °C. The results of the present investigation predict that the crystal is a stable complex with a high nonlinear optical property that can be used as a new violet-light emitting material and as an efficient optical limiter.