Investigation on growth, structural, spectral, DFT, MEP computational studies of novel methyl triphenylphosphonium bromide hydrate single crystal for third-order nonlinear optical limiting applications

A novel organic nonlinear optical (NLO) single crystal, Methyl Triphenylphosphonium Bromide Hydrate (MTPB), grown for the first time using the slow evaporation solution technique at room temperature. Comprehensive structural analysis by single crystal X-ray diffraction reveals that MTPB crystallizes in the monoclinic system with space group P2₁/n, and its lattice parameters have been accurately determined. Structural refinement was performed using the full matrix least squares technique with the SHELXL-97 program. To characterize the molecular structure and interactions, FT-IR and FT-Raman spectra provided functional group identification, and 2D fingerprint and Hirshfeld surface analyses offered insights into hydrogen bonding interactions within the crystal. The novelty extends to computational analysis, where the molecule's geometry was optimized using DFT-B3LYP with a 6–31++G(d,p) basis set, allowing comparison between theoretical vibrational frequencies and experimental data. Additionally, the third-order NLO properties were assessed via the Z-scan technique, marking the first use of MTPB in optical limiting applications. This work's innovation lies in the successful synthesis, comprehensive characterization, and demonstration of MTPB's significant potential as an optical limiter, paving the way for new NLO applications.