Self-assembled supramolecular structure of N,N,N′,N′-tetramethylethylenediammonium-bis-(4-nitrophenolate): synthesis, single crystal growth and photo physical properties

The synthesis, growth and structure of a novel organic third order nonlinear optical (NLO) crystal namely, N,N,N',N'-tetramethylethylenediammonium-bis(4-nitrophenolate) (TMEDA4NP) is presented. The solubility of the compound in methanol and acetonitrile solvents is compared and the growth conditions were optimized. Single crystals of TMEDA4NP were grown in acetonitrile solvent using a slow evaporation technique at 303 K. The crystal structure elucidated from single crystal X-ray diffraction analysis at 293 K showed that the title compound crystallizes in a monoclinic crystal system with space group C2/c. The molecular structure was further confirmed by modern spectroscopic techniques like FT-IR, FT-NMR, UV-Vis-NIR and Fluorescence. The transparency in the visible region and hence the feasibility of the crystal for NLO applications was established from UV-Vis-NIR study. Fluorescence emission of the crystal also revealed that the title compound can serve as a photoactive material. The protonation of TMEDA4NP was unambiguously confirmed from the NMR data. Thermo gravimetric analysis (TGA) showed that TMEDA4NP was thermally stable up to 110 degrees C. The mechanical strength of the crystal was assessed by a Vickers microhardness tester. Etching studies were carried out on the (100) plane of the as grown surface of the crystal. Third order susceptibility measured using the Z scan technique by employing a picosecond Nd-YAG laser indicates that the title compound can serve as a promising candidate for third order NLO applications.