T. Dhanabal

Synthesis, structure, thermal and NLO characterization of 4-hydroxy tetramethylpiperazinium picrate crystals

AbstractGood quality single crystals of 4-hydroxy tetramethylpiperazinium picrate (TMPP) were grown by slow evaporation solution growth method at room temperature. The average dimensions of the grown crystals were 0.6 × 0.2 × 0.2 cm3. The solubility of the compound was estimated using methanol and acetone. The elemental analysis confirms the formation of the compound in the stoichiometric proportion. The UV-visible transmittance study indicates that the crystal possesses minimum transmittance at 370 nm and no absorption at 470–900 nm. The Bragg peaks obtained in the powder X-ray diffraction pattern confirm its crystallinity. The thermal behaviour of the crystal was investigated using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The structure of the compound was determined by using single crystal X-ray diffraction method. The compound was found to be crystallize in the monoclinic space group P2(1)/c (a = 6.9513(8)Å, b = 11.8016(14)Å, c = 22.018(2)Å, α = 90.00°, β = 92.575(2)°, γ = 90.00°). The thermal anomalies observed in the differential scanning calorimetry (DSC) heating and cooling cycles indicate the occurrence of first order phase transition. Fourier transform infrared (FTIR) and polarized Raman spectral analyses were used to confirm the presence of various functional groups in the compound. The nonlinear optical property (NLO) of the crystal was analysed by Kurtz-Perry powder technique and found that the compound has SHG efficiency 1.5 times greater that of potassium dihydrogen phosphate (KDP). Graphical AbstractA picric acid salt, 4-hydroxy tetramethylpiperazinium picrate was synthesized and crystallized. Thermal and spectral characterizations were carried out. The XRD structure determination indicated that the compound crystallized in monoclinic system with space group P2(1)/c. The SHG efficiency of the crystal was 1.5 times greater than that of KH2DPO4.

Thermal, Spectral, and SHG Studies of 4-Piperidinium Carboxylamide Picrate Crystals

4-piperidinium carboxylamide picrate crystals were synthesized by slow evaporation method from a methanol solution at room temperature. The stoichiometric ratio of the complex was confirmed by elemental analysis. The ultraviolet-visible transmittance study indicates that the crystal possesses minimum transmittance at 360 nm and no absorption between 480 nm and 900 nm. The thermal analyses were used to analyze the thermal stability of the complex. The thermal anomalies observed in the cooling and heating curves of the differential scanning calorimetry indicate the occurrence of a first-order phase transition. Single crystal X-ray diffraction study reveals that the complex crystallizes in monoclinic system with space group P21/c. The various absorption bands observed in Fourier transform infrared spectral analysis were reasonably assigned. The second harmonic generation efficiency of the material was found to be five times greater than that of potassium dihydrogen phosphate.