Design, Preparation And Properties Of Fluorescent/Colorimetric Chemosensing Materials

It is significant to detect and/or separate metal ions in medicine, environmentalscience. Based on the principle of molecular recognition and fluorescence sensing, wedesigned and synthesized a series of reusable fluorescent materials for detection andseparation of heavy metal cations via the cooperation of “host-guest” interaction,“electrospinning” and “sol-gel” grafting reaction. All the compounds obtained werecharaeterized by IR,¹H NMR,¹³C NMR and HRMS.1. A fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modifiedinclusion complex magnetic nanoparticles （TFIC MNPs） has been synthesized via thecooperation of host-guest interaction and sol-gel grafting reaction. Powder X-raydiffraction, Transmission electron microscopy, Fourier transforms infrared spectroscopy,and UV-visible absorption and emission have been employed to characterize the material.Fluorescence and UV-visible spectra results have shown that the resultant multifunctionalnanoparticles sensor exhibits selective ‘turn-on’ type fluorescent enhancements and clearcolor change from light brown to pink with Hg²⁺. Owing to a larger surface area and highpermeability, TFIC MNPs exhibits remarkable selectivity and sensitivity for Hg²⁺, and itsdetection limit measures up to the nanomolar level in aqueous solution. The detectionlimit was found to be4.87×10^-6mol L1（based on S/N=3）.Of the most important,magnetic measurements have shown that the TFIC magnetic nanoparticles aresuperparamagnetic and they can be separated and collected easily using a commercialmagnet. These results not only solve the embarrassments in practical sensing applicationsof nanosensor, but also enable the fabrication of other multifunctionalnanostructure-based hybrid nanomaterials.2. We have successfully developed a novel fluorescent sensing system, in which therhodamine–cyclodextrin fluorophore moiety is loaded on the cross-linkedadamantane-functionalized nanofiber surface via host–guest interaction. Since the immobilization occurs by inclusion complex formation, the functionalized surfaces canbe readily synthesized and characterized. The response of these fluorescent sensing filmsfabricated in a self-assembling way is significantly faster due to the direct exposure offluorophore moieties, avoiding, at least in principle, the inner-layer diffusion problemencountered by cyclodextrin-based physically fabricated sensing films. The selectivityand sensitivity of the nanofibrous film for Hg²⁺were satisfactory and the detection limitwas found to be6.0×10^-5mol L1（based on S/N=3）.3. We have successfully developed a fluorescent nanofibrous film as a chemosensorand adsorbent for Cu²⁺in aqueous solution via copolymerization and electrospinning.The results revealed that the nanofibrous film chemosensors possessed a high selectivityand sensitivity for Cu²⁺, achieving a detection limit at the nanomolar level(1.5×10^-6mol L1（based on S/N=3）. In aqueous solution, the adsorption capacity was more than10mg of Cu²⁺ions per gram of nanofibrous film. In summary, this nanofibrous filmmakes it possible to detect and remove the Cu²⁺metrically with solid material from wastewater. Further efforts will focus on exploring new sensing materials and optimizing thecapability to the adsorption of analysis.4. Novel naphthalimide-functionalized nanofibrous film was prepared bycopolymerization and electrospinning. Vinyl naphthalimide monomer was synthesizedand then copolymerized with methyl methacrylate via solution polymerization. Thisprepared copolymer was electrospun into nanofibrous film, which is an excellent sensingmaterial and adsorbent for Cu²⁺. When the nanofibrous film was added intoacetonitrile/aqueous solution, nanobibrous film exhibits a48nm blue-shifted from487nm to439nm in fluorescence spectra. The fluorescent film shows high sensitivitiesdue to the high surface area-to-volume ratio of the nanofibrous film structures. Thedetection limit for Cu²⁺is2×10^-5M. Furthermore, the prepared materials could beutilized as an adsorbent to remove Cu²⁺in aqueous solution efficiently. The adsorptioncapacity was10.39mg of Cu²⁺ions per gram of nanofibrous film.5. A novel naphthalimide-based fluorescent sensor bearing theN,N′-bis（salicylidene）diethylenetriamine receptor was developed, which exhibited dualsignaling behaviors for Cd²⁺and Cu²⁺, and was applicable to the environmental andbiological milieus. Upon addition of Cd²⁺, the fluorescence intensity enhanced in a linear fashion with the maximum fluorescence intensity increase of about4-fold. Moreover,with the sensor1and1-Cd²⁺complex, Cu²⁺was easily recognized by markedfluorescence quenching. The selectivity and sensitivity of the sensor1for Cd²⁺weresatisfactory and achieving a detection limit at the nanomolar level （2.56×108mol L1,based on S/N=3）. The living cell image experiments demonstrated the value of sensor1in fluorescent visualization of Cd²⁺ions in biological systems.6. We have developed a simple-structured molecule as fluorescent sensor. Theexperimental results show that the sensor1provides a single-excitation, dual-emissionratiometric detection of Cd²⁺with a significant blue shift in emission and remarkablefluorescence ‘turn-on’ response in pH-neutral aqueous solution. This ratiometricfluorescent sensor displays very high sensitivity （detection limit <0.5μM）, a rapidresponse time （<10s） and high selectivity for Cd²⁺over other transition metal ions.Moreover, the cell-permeable experiment also demonstrates it can indeed visualize thechanges of intracellular Cd²⁺in living cells.