A phase-matchable nonlinear optical material N-(3-nitrophenyl)phthalimide: Synthesis, crystal growth and characterization

The N-(3-nitrophenyl)phthalimide (N3NP) single crystal of size 4 mm×1 mm×0.5 mm, sufficient enough to confirm the existence of phase-matching direction in the crystal using the Kurtz and Perry powder second-harmonic generation (SHG) measurements, was grown by slow evaporation solution growth technique using DMF solvent. Powder XRD, FTIR, CHN analysis and H1NMR technique were employed to characterize N3NP single crystal. The single crystal XRD data revealed the noncentrosymmetric crystal structure of N3NP, which is an essential criterion for SHG. The main contribution to the SHG results comes from the strong hydrogen bonds, which also appear as intense IR bands of hydrogen bond vibrations in spectral characteristics. From DT/TG analysis, the N3NP was found to be thermally stable up to 246 °C. The four C-H······O hydrogen bonds, which hold the molecules of N3NP in three-dimensional crystal lattice, are responsible for the higher thermal stability. The UV-Vis optical absorption spectrum of N3NP shows the lower optical cut off at 370 nm and was transparent in the visible region. The N3NP is a phase-matchable NLO crystal. This crystal can be used as an efficient frequency doubler and optical parametric oscillator due to its high SHG conversion efficiency.