Third-order nonlinear optical properties of three chlorinated thienyl chalcones derivatives: synthesis, structural determination and Hirshfeld surface analysis

<jats:title>Abstract</jats:title><jats:p>Three chlorinated theinyl chalcone derivatives, namely (<jats:italic>E</jats:italic>)-1-(5-chlorothiophen-2-yl)-3-(4-(methylthio)phenyl)prop-2-en-1-one (<jats:bold>I</jats:bold>), (<jats:italic>E</jats:italic>)-1-(5-chlorothiophen-2-yl)-3-(4-(dimethylamino)phenyl)prop-2-en-1-one (<jats:bold>II</jats:bold>) and (<jats:italic>E</jats:italic>)-1-(5-chlorothiophen-2-yl)-3-(2,3-dihydrobenzofuran-5-yl)prop-2-en-1-one (<jats:bold>III</jats:bold>), were synthesized and their crystal structures were determined by single-crystal X-ray diffraction analysis. Compounds<jats:bold>I</jats:bold>,<jats:bold>II</jats:bold>and<jats:bold>III</jats:bold>crystallize in the monoclinic space groups<jats:italic>P</jats:italic> 2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>(centrosymmetric),<jats:italic>P</jats:italic> 2<jats:sub>1</jats:sub>/<jats:italic>n</jats:italic>(centrosymmetric) and<jats:italic>Pc</jats:italic>(non-centrosymmetric), respectively. In all three compounds, the molecules are in a relatively planar conformation and adopt a<jats:italic>trans</jats:italic>configuration with respect to the C=C double bond. The crystal packings are stabilized by weak hydrogen-bonds, π · · · π, C–H · · · π and C–Cl · · · π interactions. The intermolecular contacts and lattice energies were further analyzed by Hirshfeld surface analysis. The third-order nonlinear optical properties of these chalcone derivatives were investigated using the single beam Z-scan technique with a 5 mW continuous wave diode laser operating at 635 nm, where compound<jats:bold>I</jats:bold>showed the highest potential for optical application with its exclusive nonlinear refractive index and nonlinear susceptibility.</jats:p>