Jianshi Du

Synthesis of AgCl/PAN composite nanofibres using an electrospinning method

A new route based on electrospinning is designed for the preparation of silver chloride/polyacrylonitrile (AgCl/PAN) composite nanofibres. The AgCl nanoparticles uniform in size, were dispersed on the surfaces of the composite nanofibres. Transmission electron microscopy (TEM) images gave direct evidence of the structure. X-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD) confirmed the presence of AgCl crystals.

Colorimetric magnetic microspheres as chemosensor for Cu2+ prepared from adamantane-modified rhodamine and β-cyclodextrin-modified Fe3O4@SiO2 via host–guest interaction

Adamantane-modified salicylrhodamine B and β-cyclodextrin-modified Fe3O4@SiO2 were assemblied by host-guest interactions which induced novel inclusion complex magnetic nanoparticles (SFIC MNPs) colorimetric sensitive for Cu(2+) being prepared. The MNPs exhibit a clear color change from colorless to pink selectively and sensitively with the addition of Cu(2+) in the experiments of UV-visible spectra, and the detection limit measures up to 5.99×10(-6)M in solutions of CH3CN-H2O =1:10. The SFIC magnetic nanoparticles are superparamagnetic according to magnetic measurements and can be separated and collected easily with a commercial magnet in nine seconds. In addition, the microspheres have also showed good ability of separating for other ions from aqueous solutions due to a large number of hydroxyl groups on the surface.

A novel magnetic fluorescent chemosensor for Cu2+ based on self-assembled systems of azobenzene and α-cyclodextrin

A novel fluorescent and colorimetric chemosensor for Cu2+ has been designed and fabricated. Host–guest interactions were used to construct inclusion complex magnetic nanoparticles (IFIC MNPs) from azobenzene-modified rhodamine 6G and α-cyclodextrin-modified Fe3O4@SiO2. A selective ‘turn-on’ type fluorescence enhancement and an apparent colour change from colourless to yellow-green with Cu2+ ions in the fluorescence experiments, and light yellow to pink in the UV-visible spectra, can be achieved. Good selectivity and sensitivity for Cu2+can be gained with the IFIC MNPs, with a detection limit of 2.5 × 10−7 M in MeCN/H2O = 1 : 1. Furthermore, the IFIC magnetic nanoparticles can be separated and recycled easily using a magnet due to their superparamagnetism.

Fluorescent magnetic nanosensors for Zn2+ and CN− in aqueous solution prepared from adamantane-modified fluorescein and β-cyclodextrin-modified Fe3O4@SiO2 via host–guest interactions

A novel multifunctional fluorescent chemosensor has been constructed with a highly selective “off–on” behavior, recoverability and recyclability based on β-CD/AD (adamantane) host–guest self-assembly interactions. Adamantane-modified fluorescein/cyclodextrin-modified Fe3O4@SiO2 inclusion complex magnetic nanoparticles (FFIC MNPs), which can provide a specific green fluorescence enhancement in response to Zn2+, have a detection limit of 4.5 × 10−7 mol L−1 in CH3CN : H2O (1 : 4, v/v). The spirolactam ring in the fluorophore moiety would be open with the introduction of Zn2+, while it could recover as long as the zinc in the complex is removed. Meanwhile, one gram of FFIC MNPs can adsorb 6.1 mg zinc. Therefore, the derivative chemosensors, FFIC MNPs–Zn, are available to respond to CN− due to the fluorescence quenching under UV (ultraviolet) radiation with a detection limit of 7.7 × 10−7 mol L−1. Furthermore, the FFIC MNPs exhibit great reusability and recyclability in aqueous solution on account of their magnetism and reproducibility. We recycle the residual MNPs to detect Zn2+ repeatedly for at least 4 times, after readily adsorbing the complex zinc with excess CN−, and the same principle also works in reverse. If the fluorophore moiety is inactive, we could also wash out the useless fluorescent molecules from the MNPs (hosts) and then reassemble new fluorescent small-molecules (guests) to maintain the efficient properties of the probe in responding to Zn2+ and CN− for at least 7 times.

Role of Adamantane Amide Based on L-Proline Double-H Potential Organocatalyst in Aldol Reaction with Product Separated via Host-guest Interaction

Chiral organocatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under‒20 °C. A series of aldol products was obtained from moderate to good yields(up to 98%) with excellent diastereoselectivities(up to >99:1) and enantioselectivities(up to >99%). The aldol products in the system were separated by α-cyclodextrin via host-guest interaction and determined by chiral HPLC. The catalyst could be reused up to five times. The 4-substitution position played an important role in diastereoselectivity and enantioselectivity.

A Highly Selective and Sensitive Ratiometric Fluorescent Probe for Hypochlorite and Its Application

A novel water-soluble hybrid fluorescein-coumarin dye(FLNC) fluorescence ratiometric probe to recognize OCl− was designed and synthesized. The most prominent feature of the probe is that the molecular structure contains two different fluorophores, and the fluorescein moiety was connected to coumarin moiety by diacylhydrazine linker. When OCl− was added, the two fluorophores in the FLNC probe could have a rapid respond simultaneously, with high selectivity and sensitivity towards OCl– among other reactive oxygen species/reactive nitrogen species(ROS/RNS) and anions, and the detection limit was measured to be 0.30 μmol/L. In addition, the color changes of the solution could be observed by the naked eye and have a short response time(completed within 1 min), which suggestes that the probe FLNC has the potential to be used for real-time detection.