Yuzhen Zhao

Investigation on Fluorescence Quenching Mechanism of Perylene Diimide Dyes by Graphene Oxide

Perylene diimide derivatives were used as probes to investigate the effect of the molecular structures on the fluorescence quenching mechanism in a perylene diimide/graphene oxide system. The electrons transferred from the excited state of dyes to the conductive band of graphene oxide with different concentrations were determined by fluorescence spectra. The results indicated that the quenching efficiency of perylene diimides by graphene oxide was not only dependent on the difference between the lowest unoccupied molecular orbital level of dyes and the conduction band of the graphene oxide, but also mainly on the difference in the molecular structures.

Facial strategy for radical species through Ag(I)-mediated oxidation of the alkyl trifluoroborates

ABSTRACT A rapid and highly efficient method for the radical formation using potassium alkylfluoroborates as radical precursor is devised and developed which conducts under relatively mild condition using silver(I) oxide as the oxidant. The observed silver mirror phenomenon hints at the fact that Ag2O is the real oxidant. This approach effectively overcomes the drawbacks-stringent reaction conditions and poor tolerance of a variety of functional groups. GRAPHICAL ABSTRACT

Blue phase liquid crystals stabilized by graphene oxide modified with aminoalkyl group

ABSTRACT In the present work, the graphene oxide/blue phase liquid crystal composites and long aminoalkyl chains functionalized graphene/blue phase liquid crystal composites were prepared by doping the additives into a blue phase exhibiting liquid crystal host. It is found that the blue phase temperature range could be widened by dispersing a small amount of functionalized graphene. It suggests that anisotropic two-dimensional flake nanoparticles may be of great usefulness for stabilizing blue phases.

Preparation of an ionic liquid-based hydrogel with hyperbranched topology for efficient removal of Cr(VI)

An imidazolium salt-based hydrogel with hyperbranched topology (hbGel-PEG-TTIm+Br6−) was proposed for efficient adsorption towards anionic hexavalent chromium ions (Cr(VI)). For the purpose, a bromo-terminated A3 type monomer and a imidazole-terminated B3 type monomer were firstly synthesized via O-esterification and Michael addition, respectively. Then, hbGel-PEG-TTIm+Br6− was obtained by the one-pot step polymerization of “A3u2009+u2009B3” approach via N-alkylation reaction. The chemical structure and morphology of the as-prepared hydrogel were confirmed by Fourier transform infrared and scanning electron microscope. The cross-linking network structure was calculated according to the Flory–Rehner equilibrium swelling equation. The effects of solution pH, adsorbent dosage, contact time and initial Cr(VI) concentration on the adsorption performance were also investigated, and the maximum adsorption capacity could reach ~u2009238xa0mgxa0g−1. In addition, the adsorption process of Cr(VI) on hbGel-PEG-TTIm+Br6− was well described by the pseudo-second-order kinetic model, and the adsorption equilibrium data fitted with Langmuir isotherm model better than Freundlich isotherm model. This novel hydrogel with hyperbranched topology can potentially be applied in the treatment of wastewater containing Cr(VI).

Au monolayer film coating with graphene oxide for surface enhanced Raman effect

A self-terminated electrochemical atomic layer deposition process is developed to fabricate Au monolayer (ML) film layer-by-layer. It is found that the under potential deposited hydrogen (Hupd) provides perfect termination after each ML deposition and the further ML growth can be replicated after a surface activation using a positive potential to remove the Hupd layer. Voltammetric measurements, deposition current analysis, and EQCM show clear characteristics of UPD hydrogen surface termination and the ML deposition. Both XRR and HREED confirm the Au ML film formation. Moreover, the Au ML film appears to be effective for surface enhanced Raman effect of GO on the Au ML film.

Advanced electro-optic properties of nematic liquid crystal doped with high birefringence liquid crystal molecules

ABSTRACT The study of fast response nematic liquid crystal display material mixture and synthesis about compounds has always been an important subject in recent years. In this article, one type of high birefringence liquid crystal based on phenyl-diacetylenes was synthesized by sonogashira coupling reaction. A research is conducted on the effect of electro-optic properties of a widely used nematic liquid crystal mixture doped with the prepared high birefringence liquid crystal molecule which concentrations ranging from 1% to 5 wt%. While the results show that the steepness of electro-optic curves first increase and then decrease with the prepared high birefringence liquid crystal molecule content increasing, when the content of high birefringence liquid crystal molecule reaches 3%, electro-optic properties of the mixture liquid crystals are excellent.

A new-type composite film of cholesteric liquid crystal doped with PCBM for laser-damage prevention in both visible and near-infrared region

ABSTRACT Nowadays, with the increasing use of high-power laser, research and development of laser-damage prevention materials with multifunctional features and wideband wavelengths are urgent and indispensable. In the paper, cholestric liquid crystal (ChLC) is first proposed to be doped with a high-efficiency optical limiting material, 6, 6-phenyl C61-butyric acid methyl ester (PCBM), to fabricate a new-type laser-damage-prevention film. The ChLCs have the desired reflection wavelengths covering 750–2300 nm, which is an effective and potential candidate for the prevention of continuous or tuneable laser in near infrared (NIR) region. Meanwhile, the solubility of PCBM in LC and its nonlinear absorption property of are discussed, and it was proved that the good solubility of PCBM in LC contributed to the excellent nonlinear absorption of mixture (LC doped with PCBM). Taking advantages of this phenomenon, a novel composite film of ChLCs doped with PCBM is prepared by UV polymerization. As a result, the composite film not only performs broadband reflection in NIR region, but also exhibits a strong nonlinear absorption and excellent optical limiter properties in visible region, which proves the films potential application in laser damage prevention.

Synthesis and mesomorphic properties of novel high birefringence azobenzene liquid crystals with lateral fluorosubstituent

ABSTRACT In order to obtain liquid crystals with high birefringence (Δn), four azobenzene compounds based on lateral fluorinated bistolane moieties with trifluoromethyl terminal groups were synthesized with Hagihara–Sonogashira cross-coupling reaction. The molecular structures of the compounds were confirmed by Fourier transform infrared, 1H-nuclear magnetic resonance. The transition temperatures, optical textures, and optical anisotropies were determined by differential scanning calorimetry, polarizing optical microscopy. The effect of the alkyl substituents on liquid crystal behavior is discussed in detail. The compounds have showed higher birefringence values.