Role of direction of charge transfer on the nonlinear optical behavior of pyridine substituted chalcone derivatives

• New efficient NLO single crystals are grown by slow evaporation technique.
• A change in the direction of charge transfer resulted in noncentrosymmetric structure and nonlinearity.
• The molecular dipoles aligned in zigzag layered fashion results in good SHG efficiency.

High quality single crystals of an efficient novel nonlinear optical (NLO) chalcone derivative 3-(4-nitrophenyl)-1-(pyridine-3-yl) prop-2-en-1-one (4NP3AP) that are transparent in the entire visible and infrared region are grown by the slow evaporation solution growth method at ambient temperature. The single crystal XRD studies reveal that the crystal belongs to monoclinic system with the noncentrosymmetric space group P21. The presence of functional groups in the compound is confirmed by different spectroscopic techniques. The surface morphology of the crystal is studied by scanning electron microscopy. The second harmonic generation (SHG) efficiency of 4NP3AP determined by Perry and Kurtz method is 56% that of potassium dihydrogen phosphate (KDP) single crystals. The static and frequency dependent molecular hyperpolarizabilities were computed using MOPAC 2012. Thermal analysis confirms that the crystal is thermally stable up to 177 °C. The origin of nonlinearity and the role of charge transfer direction on the nonlinearity of the chalcone have been discussed in detail.

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