Comprehensive study of the molecular structure and nonlinear optical response of two novel halogenated pyrenyl-chalcones

Herein, two novel pyrenyl-chalcone derivatives named PCh-1 and PCh-2 were synthesized by the Claisen-Schmidt reaction and successfully recrystallized in acetone to get single crystals. The crystals were spectroscopically characterized via SCXRD and UV–Vis absorption. Quantum computational studies including NBO, MEP, FMO, and polarity were performed using DFT at B3LYP/6–311++G (d,p). Intermolecular interactions were investigated using Hirshfield analysis while intramolecular interactions were discussed experimentally (UV–Vis absorption spectroscopy) and theoretically using TD-DFT at CAM- B3LYP/6–311++G (d,p). The presence of the intermolecular interactions of CH…O, CH…F, CH…π, and π-π interactions stabilize both crystals in head-tail (PCh-1), zig-zag fashion (PCh-2), and face to face stacking. The hyper conjugative interactions extracted from NBO analysis confirmed the high stability of both crystals. The UV–Vis and FMO studies show low bandgap energy of 3.012 eV (PCh-1) and 3.047 eV (PCh-2) and opaque in the visible range revealing strong ICT. The nonlinear behavior of the compounds was investigated using the Z-scan technique via CW laser working at 637 nm. An excellent NLO response in order of 10−5 esu (PCh-1) & 10−6 esu (PCh-2) and fast response in limiting optical signal at 1245.5 mW (PCh-1) & 1431.9 mW (PCh-2) are observed. The structure-property findings suggest the higher inter/intramolecular charge transfer in PCh-1 compared to PCh-2 is due to the strength of the EDG, planarity of the bone structure, and polarizability. The high NLO performance of the crystals suggests a promising application to use them as NLO material.