Synthesis, Growth, Crystal Structure and Characterization of an Organic Salt Single Crystal: Diimidazolium Dipicrate Monohydrate

The organic salt of Diimidazolium dipicrate monohydrate (DIDPMH) has been synthesized and single crystals grown by slow solvent
evaporation solution growth technique at room temperature using dry acetonitrile as the solvent. The 1H and 13C NMR spectra were
recorded to confirm the presence of different proton environments and different kinds of carbon atoms respectively. The molecular
structure of the title crystal was established by single crystal X-ray diffraction technique and it belongs to monoclinic crystal system with the space group P21/m and the unit cell parameters are a=6.8527(3) Å, b=23.4396(2) Å, c=8.1335(6)Å. The functional groups present in the crystal were confirmed by FT-IR analysis. The optical transmittance window and the lower cut-off wavelength of the DIDPMH crystal have been identified by UV-Vis-NIR transmittance study. A fluorescence emission study shows that the title crystal has greenorange fluorescence emission. The second harmonic generation (SHG) was confirmed by modified Kurtz-Perry powder method and it is found to be 0.2 times that of potassium dihydrogen phosphate (KDP) crystal. The thermal stability of the title crystal was investigated by TG/DTA analyses and differential scanning calorimetry. The surface morphology of the grown DIDPMH crystal was studied by scanning electron microscopy (SEM).