A long-chain based bromo and methyl substituted chalcone derivatives; experimental and theoretical approach on nonlinear optical single crystals

In the present work, growth of single crystals of chalcone derivatives {4-[(1E)-3-(4-methylphenyl)-3-oxoprop-1-en-1-yl]phenyl4-methylbenzene-1-sulfonate} ( 4M1PMS) and {4-[(1E)-3-(4-bromophenyl)-3-oxoprop-1-en-1-yl]phenyl4-methylbenzene-1-sulfonate} (4BPMS), at room temperature is reported. The spectroscopic techniques are used to identify the presence of functional groups in the materials. The single-crystal XRD and powder XRD analysis reveals that 4M1PMS belongs to non-centrosymmetric (P2(1)2(1)2(1)) and 4BPMS belongs to centrosymmetric (P2(1)/n) crystalline system. The molecular structures exhibit C-H center dot center dot center dot O and pi center dot center dot center dot pi intermolecular interactions. From UV/VIS/NIR spectroscopic studies, it is found that both samples have bathochromic shifts in linear absorbance (cut-off region) spectra. The broad emission region involved in several sharp emission peaks in blue region, exhibits a blue light emission property, as observed from photoluminescence study, in both the samples. The thermal stability of the materials were studied by TGA/DTA techniques and crystals were thermally stable until the melting point. In NLO study, 4M1PMS crystal has shown SHG efficiency 2.2 times that of KDP crystal. In addition, electronic contribution in hyperpolarizability (first order and second order) tensors of both the compounds were computed theoretically by M06-2X functional at DFT level. The open/closed aperture Z-scan technique were performed to evaluate third order nonlinear optical materials by measuring experimental parameters such as nonlinear absorption/refraction and calculate second-order hyperpolarizability with corresponding third-order nonlinear optical susceptibility (chi((3))) of 4M1PMS and 4BPMS. The surface damage threshold studies of 4M1PMS and 4BPMS were performed by Q-switched Nd:YAG laser at 532 nm.