Synthesis and nonlinear optical properties in the near-IR range of stilbazolium dyes.

A series of stilbazolium salts based on donor-π-acceptor (D-π-A) structure have been synthesized and fully characterized. Photophysical properties including linear absorption, one-photon excited fluorescence (OPEF), two-photon absorption (2PA) properties were systematically investigated. The results suggest that increasing electron-releasing character of the terminal group leads to a more pronounced donor-to-acceptor intramolecular charge transfer (ICT). In addition, the dyes possess the largest 2PA cross sections in the near infrared region (NIR) and display maximum two-photon absorption cross sections within the narrow wavelength range from 950 to 970nm and BL3 exhibits a large nonlinear refractive index coefficient and possesses very large values of the real part of the cubic hyperpolarizability χ((3)) at 960nm. Furthermore, the initial density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations provide reasonable explanations for their absorption spectra, meanwhile we used the Lippert-Mataga equation to evaluate the dipole moment changes of the dyes with photoexcitation, the results are corresponding with linear and nonlinear optical properties of the dyes.

Synthesis and characterization of hexagonal NiTe2 nanoplates.

Single-crystalline NiTe2 nanoplates have been synthesized on a large scale through a hydrothermal reaction of Ni(CH3COO)2 and TeO2 at 210 degrees C for 48 h. The NiTe2 nanoplates have hexagonal shape. The average edge sizes and thicknesses of nanoplates are 350 nm and 85 nm, respectively. Here, Ethylenediaminetetraacetic acid (EDTA) is employed as a chelating agent. Furthermore, EDTA plays crucial roles in controlling phase composition and morphology of the resultant products.

Selected synthesis of CuS nanotubes and hollow nanospheres at room temperature.

A solution route has been developed to synthesize covellite (CuS) nanostructures through the precitation reaction of CuCl2.2H2O, thiourea (Tu), and NaHCO3 in distilled water at room temperature. By regulating the concentration of Tu, CuS nanotubes and hollow nanospheres with diameters of 100-200 nm have been selectively prepared. Structural characterizations indicate that both nanotubes and hollow spheres are composed of CuS nanoparticles with diameters of about 5-10 nm. UV-Vis absorption and room temperature photoluminescence (PL) spectra display different morphology-related absorption phenomena for nanotubes and hollow nanospheres. A systematic investigation has been carried out to understand the factors influencing the CuS morphology. Two different routes are identified to explain the formation of the nanotubes and hollow nanospheres herein.