A novel carbazole quaternary ammonium compound（abbreviated as T_2） had been synthesized and characterized by ~1H NMR, ^（13）C NMR and Mass spectrometry. The single-crystal structure has been determined by X-ray single-crystal diffraction. The electrochemical and two-photon absorption properties of T_2 were systematically studied by cyclic voltammetry and Z-scan determination methods, respectively. The results suggested that T_2 had a good oxidation-reduction and excellent nonlinear optical property. The two-photon absorption（TPA） value has a maximum corresponding to cross section σ = 7963.3 GM（Goeppert-Mayer units） at 700 nm, indicating potential applications in nonlinear optical materials. Furthermore, attributing to the excellent water solubility and low cytotoxicity, the compound was explored on its primary application in biological imaging.
A novel pyrazole derivative ligand, BTA（BTA = bis-（4-ethoxy-phenyl）-[4-（tripyrazol-1-yl-methyl）-phenyl]-amine）, was synthesized and fully characterized by 1H-NMR, MALDI-TOF-MS spectra and single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1, with a = 11.827（1）, b = 16.000（2）, c = 16.527（2）A, α = 108.510（1）, β = 91.116（5）, γ = 101.734（1）°, V = 2894.5（6） A3, Z = 1, Dc = 1.262 g/m^3, F（000） = 1162, Μr = 545.63, μ = 0.083 mm-1, the final R = 0.0728 and w R = 0.2213 for 7541 observed reflections with I 〉 2（I）. The structural analysis revealed that three pyrazole units are attached to the same carbon atom connected with bis-（4-ethoxy-phenyl）-phenyl-amine group. UV-vis spectral features of the ligand in various solutions were explained by time dependent density functional theory（TD-DFT）. It was also found that the ligand（BTA） exhibits an exclusively selective and sensitive response toward Fe3＋ using UV-vis spectroscopic method.
