Yiqin Yang

Properties of novel polyvinyl alcohol/cellulose nanocrystals/silver nanoparticles blend membranes.

Novel polyvinyl alcohol (PVA) blend membranes containing cellulose nanocrystals (CNs) and silver nanoparticles (AgNPs) were prepared via a simple method. CNs were prepared by sulfuric acid treatment of microcrystalline cellulose. AgNO3 aqueous solution mixed with the CNs aqueous suspension and was reduced by NaBH4 at room temperature. Purified CNs/AgNPs nanocomposites as functional fillers mixed with polyvinyl alcohol to prepare blend membrane. The morphology, mechanical properties, and antibacterial activities of PVA/CNs/AgNPs composite films were investigated. The PVA/CNs/AgNPs composite films were stable and homogeneous. The tensile strength of PVA was increased from 57.02 MPa to 81.21 MPa when filled with CNs/AgNPs. Antibacterial ratio of PVA/CNs/AgNPs composite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was 96.9% and 88.2%, respectively. The CNs/AgNPs nanocomposites could be applied as bi-functional nanofillers within PVA to improve the mechanical properties and antibacterial activities.

Design, synthesis and anticancer activity of novel nopinone-based thiosemicarbazone derivatives

A series of new nopinone-based thiosemicarbazone derivatives were designed and synthesized as potent anticancer agents. All these compounds were identified by 1H NMR, 13C NMR, HR-MS spectra analyses. In the in vitro anticancer activity, most derivatives showed considerable cytotoxic activity against three human cancer cell lines (MDA-MB-231, SMMC-7721 and Hela). Among them, compound 4i exhibited most potent antitumor activity against three cancer cell lines with the IC50 values of 2.79±0.38, 2.64±0.17 and 3.64±0.13μM, respectively. Furthermore, the cell cycle analysis indicated that compound 4i caused cell cycle arrest of MDA-MB-231 cells at G2/M phase. The Annexin V-FITC/7-AAD dual staining assay also revealed that compound 4i induced the early apoptosis of MDA-MB-231 cells.

A novel hexahydroquinazolin-2-amine-based fluorescence sensor for Cu2+ from isolongifolanone and its biological applications

Pyrimidine-based derivatives 2a–2c were synthesized from renewable isolongifolanone, and compound 2c exhibited high selectivity and sensitivity toward Cu2+ ions with a low detection limit of 4 × 10−8 M, a wide pH range (5–11), and a short response time (30 s). The sensor still retained good fluorescence selectivity to Cu2+ ions when applied to fluorescence imaging in living black mice. Therefore, compound 2c can be used as an effective fluorescence probe and imaging agent for detecting Cu2+ ions.

Fluorescence staining of salicylaldehyde azine, and applications in the determination of potassium tert-butoxide

Salicylaldehyde azine (1), with an aggregation-induced emission (AIE) function, was synthesized from salicylaldehyde and characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high resolution mass spectrometry (HRMS), and X-ray single crystal diffraction. Compound 1 exhibited high thermal stability and good light-emitting behavior in the solid state. It could be preferably used to dye cellulose and KBr. No obvious changes in fluorescence intensity occurred when compound 1 was dissolved in different pH buffer solutions. The addition of TFA led to slight fluorescence quenching, and the fluorescence intensity gradually increased with increasing potassium tert-butoxide solution concentrations. The fluorescence intensity of compound 1 showed a good linear relationship with the concentration of potassium tert-butoxide (0.5–4.0 × 10−4 M), y = 99.193x + 93.599, R2 = 0.9902; the limit of detection (LOD) was 1.07 × 10−7 M. It could measure the content of potassium tert-butoxide with a relative standard deviation (RSD) value of 1.5%.

Nopinone-based aggregation-induced emission (AIE)-active difluoroboron β-diketonate complex: photophysical, electrochemical and electroluminescence properties

Four difluoroboron (BF2) β-diketonate nopinone complexes 3a–3d that exhibited typical aggregation-induced emission (AIE) properties were synthesized using the natural renewable β-pinene derivative nopinone as the starting material. The thermal, photophysical, electrochemical and electroluminescent properties as well as the AIE properties of complexes 3a–3d were analyzed systematically. The data of photophysical and electrochemical demonstrated that compound 3b with a methoxy group exhibited the largest bathochromic shift, the highest absolute photoluminescence quantum yields and narrowest optical bandgap among 3a–3d. Using 3b as the emitter, electroluminescent (EL) device I exhibits blue-green light with CIE coordinates of (0.2774, 0.4531) and showed a better performance with a luminous efficacy (ηp) of 7.09 lm W−1 and correlated color temperature (TC) of 7028 K. The results demonstrate that new AIE compounds are promising solid-state luminescent materials with practical utility in electroluminescent materials.

Synthesis, optical properties, and acid–base indicating performance of novel ketene hydroxybenzylidene nopinone derivatives

Three ketene nopinone derivatives (1–3) were successfully synthesized from β-pinene derivative nopinone and characterized by Fourier transform infrared spectroscope (FT-IR), nuclear magnetic resonance (NMR), mass spectrometry, and X-ray single crystal diffraction. Then, their optical properties were investigated by ultraviolet-visible and fluorescence spectroscopy. The ethanol solutions of compound 1 or 3 could change color from colorless to saffron yellow and Kelly, respectively, after adding NaOH solution. Moreover, the addition of potassium tert-butoxide could lead to a change in the UV-vis absorption and fluorescence spectra and enhance fluorescence, with compounds 1 and 3 being greatly affected by alkali. A good linear relationship between fluorescence intensity and pH values (9.01–13.38) was obtained for compound 2 (for detecting further pH value, y = 10.178x − 61.806, R2 = 0.9934). Compounds 1 and 3 were ideal acid–base indicators because of their high sensitivity, which was better than that of phenolphthalein. Therefore, these new nopinone derivatives may be candidates for future acid–base indicators.