| Low molecular weight gel (LMWG) is a kind of soft material to acheieve theaggregation of self-assembled. It have attracted considerable attention due to itsunique structure and wide application. It is very easy to be modified, so canintroducted a variety of functional groups in the structure to become a smartresponsive gel. The system of responsive gel can be either switched on-off or tuned inthe presence of an external or internal chemical or physical stimulus such as light,ionic strength, electric or magnetic fields, mechanical stress, pH changes, chemicalreaction, ultrasound and so on. Such responsive gel systems are highly desirable forthe development of sensor devices and have potential applications in chemical sensors,light harvesting system, template synthesis, molecular recognition, drug delivery,photoelectric materials and release etc.. Based on our previous studies, we havedesigned and synthesized three anthracene hydrazone derivatives, they are AHP-T8,AHP-mB8, AHP-oB8. Their gelation behaviour, luminescence properties andcolorimetric fluoride-responsive behaviour both in the solution and in the gel statewere studied.1, We have studied the properties of new three super gelator AHP-T8, AHP-mB8,and AHP-oB8. They show an excellent gelation ability towards most organic solventsuch us aromatic solvents, ethanol, amyl alcohol, dimethylsulfoxide and cyclohexaneat very low concentrations. The originic gels was quit stable for several mouths atroom temperature without precipitation and crystallization.2, We also studied the thermal stability, morphology and structure information ofthe three kinds of gel systems used many testing metnods sucn as scanning electron microscopy(SEM), fourier transform infrared spectroscopy(FT-IR), nuclear magneticresonance hydrogen spectrum(1H NMR) of temperature, ultraviolet-visible absorptionspectrometry (UV-vis). The study found that the main driving forces of the gelformation are intermolecular hydrogen bonds between hydrazone group, π-πinteractions between anthracene and van dar Wall interactions between alkyl chain. Inthe synergistic effect of these forces, gel formation factor directed fiber tape, the fiberentanglement structure with three-dimensional fiber network.3, Study on luminescent propertiy of AHP-T8, AHP-mB8, AHP-oB8organic gelsused the fluorescence emission spectra. The study found that, the gelators AHP-T8,AHP-mB8, AHP-oB8of an anthracene unit, a hydrazone and long alkyl chainsformed stable gel with dramatically enhanced fluorescence emission compare to itsmother solution.4, We have study on the anion response properties of three kinds of organic gelsystems. The study found that three kinds of organic gel can response to fluoride ionselectively both in the solution state and in the gel state. The gel systems couldselectively respond to fluoride ion with gel-sol transition and color change. But thesolution could selectively respond to F-with color change. Organic gel systemresponse to fluoride ion with dual channel achieve the naked eye visual detection offluoride ion.5, The resulting organogels were demonstrated to be promising colorimetric andfluorescent sensors toward fluoride ions with high sensitivity and selectivity,accompanying the disruption of the gelators. Spectroscopic study and nuclearmagnetic resonance hydrogen spectrum titration experiment revealed that thedeprotonation of the hydrogen atom on the N position of hydrazone moiety byfluoride ions is responsible for the recognition events, evidenced by immediatetransformation from the sol phase to the gel state upon adding a small amount of aproton solvent, methanol. In addition, the deprotonation of the hydrogen atom on theN position of hydrazone moiety influence the intramolecular charge transfer, resultingin the color change of organic gel system.The results might provide a strategy to design a novel gelator for constructing stimuli responsive soft materials and providethe basis for the development of non-fluid systems for sensing anion with the nakedeyes. |
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