Synthesis, crystal growth and characterization of a new organic NLO material: Caffeinium picrate (CAFP)—A charge transfer molecular complex salt

Good-optical-quality single crystals of caffeinium picrate (CAFP), a new organic charge transfer molecular complex salt, were successfully grown by the slow evaporation solution growth technique at room temperature. Formation of the new crystal has been confirmed by single-crystal X-ray diffraction (XRD) and NMR spectroscopic techniques. CAFP crystallizes under monoclinic system with cell parameters a=8.2996(10) Å, b=9.0014(11) Å and c=23.0210(3) Å. The suitability of this material for optical application was studied by optical transmission spectroscopy. Fourier transform infrared (FT-IR) spectral analysis was used to confirm the presence of various functional groups in the grown crystals. The thermal stability of the crystal was investigated using thermogravimetric and differential thermal analyses studies. The nonlinear optical (NLO) property of the crystal was confirmed by the Kurtz–Perry powder second harmonic generation (SHG) test.