Molecular structure and third-order non-linear optical properties of two novel tetralone-based chalcone derivatives: Promising materials for optical limiting applications

Abstract

Two novel tetralone-based chalcone derivatives (2E)-2-(3,4-dimethoxybenzylidene]-3,4-dihydro-2H-napthalen-1-one (DMDN) and (2E)-2-(3,4-dimethoxybenzylidene]-6-methoxy-3,4-dihydro-2H-napthalen-1-one (DM6MDN) have been synthesized via a Claisen–Schmidt condensation reaction. Single crystals were obtained using a slow evaporation solution growth method. Structural characterization was carried out using single crystal X-ray diffraction study. Non-centrosymmetric DMDN crystallized in the orthorhombic system with a P212121 space group. Centrosymmetric DM6MDN crystallized in the monoclinic system with a P21/c space group. Hirshfield analysis of both crystals revealed the existence of C–H···π and π···π interactions, which play an important role in creating supramolecular structures. Our TG-DSC study revealed that DM6MDN has higher thermal stability than DMDN. The linear absorption coefficient of DMDN and DM6MDN were calculated from our UV spectral analysis and their respective optical band gaps were calculated to be 2.88 and 3.05 eV, respectively. The photoluminescence spectra show emission peaks in the blue region. DMDN exhibits SHG activity and a large β value when compared to DM6MDN. The third-order NLO properties of the chalcone derivatives was investigated using the Z-scan technique. The obtained crystals show strong non-linear absorption (NLA) and negative non-linear refraction (NLR) for DMDN and a positive NLR for DM6MDN. The third-order non-linear susceptibility (χ(3)) was of the order 10−7 esu. DMDN and DM6MDN also exhibit optical limiting (OL) and optical switching behavior under continuous wave excitation. The static NLO parameters, such as dipole moment (μ), polarizability (α) and first order hyperpolarizability (β), were computed using the B3LYP/6–31++G(d,p) level of theory. The Donor-π-Acceptor-π-Donor (D-π-A-π -D) system of DMDN and DM6MDN also makes them promising materials for NLO applications.