Design, Synthesis And Optoelectronic Properties Of Sulfur Ligands Gold Nano-composites Modified By The Ligands

Nano-Au/organic composite materials received much attentions because of their special structures and excellent performance. Conjugated organic molecules bear high electron mobility, nano-materials exhibit quantum size effect, quantum tunnel effect et. al.. Base on reviewing recent literatures, we assembled thiol organic ligands with inorganic units to get excellent compositions. The main contents and achievements are listed as following:(1) Based on our group’s previous research work, novel type of (D-π-A) structure organic ligands with functional moieties were obtained through the Witting condensation, Aldol condensation, formylation, acetylation, et. al.. Among these ligands, three aldehydes react with2-Aminothiophenol, generating thiazole ring, which is one of the innovations. All the ligands are characterized by IR,1HNMR,13C NMR, MS spectra, elemental analysis. Single crystals of L1/L2/L4were obtained and determined by X-ray crystallography, belonging to the crystal system of triclinic, monoclinic, monoclinic, respectively, and the space group of PI, P21/c, respectively. The optical properties of the six ligands were investigated systematically, such as UV-vis, single-photon fluorescence, time-resolved fluorescence, Z-Scan technique and two-photon absorption properties. The transitions were assigned further with aid of theoretical calculation, confirming that the transition from HOMO to LUMO belongs to typical π-π*transition. The results show that the introduction of ethyoxyl groups into triamine will decrease two-photon absorption sections.(2) Different proportion of the solutions is made up, which consist of the thiol ligands L1-4with excellent optical properties and HAuCl4-4H2O(the ratios of L1-4:HAuCl4·4H2O are1:1,2:1,3:1,4:1,5:1,6:1,7:11:1,2:1,3:1,4:1,5:1,6:1,7:1, respectively). Au(III) is reduced to Au(0) without any reductant, and then the nano-Au were modified by the ligands to obtain micro-nano-gold organic composite in situ.(3) The optical properties of the modified gold nanopartical composite induced by femtosecond laser, including UV-vis, single-photon fluorescence, two-photon absorption, transmission electron microscopy(TEM) and particle size test. The results show that the micro-nano-gold organic composite with2nm is prepared; their spectra exhibit a red-shift compared to that of their ligands. The two-photon fluorescence intensity strengthened with the increasing ratio of L:HAuCl4·4H2O and then decrease. There is a maximum fluorescence intensity when L:HAuCl4·4H2O is3:1. Therefore, there should be best optimized ratio for the preparation process.