Synthesis And Properties Of Ions Responsive Smart Supramolecular Gel Based On Long-chain Alkoxy Double Aroyl Hydrazone

This paper includes four chapters:Chapter 1: This chapter introduces the mechanisms of self-assemble in low molecular weight organic gels, the research significance and the latest research progress of stimulus-responsive gels formed by low molecular weight Organic gelators are exposited. In term of the different types of stimuli-responsive, external stimuli can be classified into two main groups, physical and chemical. In the first group, physical stimuli can be subdivided into five categories:(1) thermo-responsive type(2) p H-responsive type light-responsive type(3) mechanical stress- responsive type(4) ultrasound-responsive(5) electric or magnetic field-responsive type. In the second class, chemical stimuli can be subdivided into six categories:(1) ion-responsive type(2) pH-responsive type(3) redox-responsive type(4) non-covalent interactions-responsive type(5) covalent bonding-responsive type(6) Enzymes-responsive type. In addition, there is a class with multiple stimuli-responsive properties of the gel, it may also have physical and chemical stimuli-responsive performance.Chapter 2: a low molecular weight organic gelator(L1) based on acyl hydrazone was designed and synthesized by using dimethyl 5-hydroxyisophthalate. The gelator was synthesized via etherification, hydrazinolysis and aldimine condensation reactions under mild reaction conditions with high yield and it was characterized by IR, 1HNMR and element analysis. The gelator showed excellent gelation ability in ethyl acetate, it could form stable organogels(OGL1) in ethyl acetate via self-assemble with very low critical gelation concentrations. The self-assembly mechanism was investigated by concentration dependent 1HNMR, FT-IR and X-ray diffraction, these experiments indicate that the gelator L1 self-assembled to supramolecular organogel OGL1 by the hydrogen bonds, π–π stacking as well as the vdw existing in the long alkyl chains. OGL1 showed specific selectivity for F-, other common anions could not lead to any similar response. After addition of solid TBAF, the colorless OGL1 gel changed to yellow sol. The anion response mechanisms of OGL1 were investigated by UV-vis spectral titration and 1HNMR titration with F-. The phenomenons indicate that with the addition of F- the hydrogen bonds was destroyed and N–H group might undergo a deprotonation process.These reasons lead to the colorless OGL1 gel changed to yellow sol. Therefore, OGL1 could act as a Fresponsive smart material.Chapter 3: A novel low molecular weight organic gelator L2 based acyl hydrazone group as binding site and naphthalene group as the fluorescence signal group were designed and synthesized and it was characterized by IR, 1HNMR and element analysis. Through a series of experiments, we found that L2 can gelate in ethyl acetate and form stable organogels(OGL2). The property of metal ion responsiveness of the gel was investigated. It is very interesting that, The organogel showed a slow response to Cd2+, Pb2+ and Cr3+, producing gel–gel transitions with the change in color and fluorescence intensity upon addition of these metal ions. The cation response mechanisms of OGL2 were investigated by IR and 1HNMR. The phenomenons indicate that with the addition of cation, gelator with cations coordinated by different coordination modes. The unequal coordination modes cause changes in the structure of self-assembled, leads to a series of transformation in gel properties. Moreover, we also found that when the CN- added to host L2, the blue fluorescence was quenched. Thus, gelator L2 not only as a smart material could response to cation stimulate, in the detection of CN- also has potential applications.Chapter 4: 5-(2-hydrazinyl-2-oxoethoxy)isophthalohydrazide, an important intermediate for gelator, functional complexes, and drug molecules L3, was synthesized by using dimethyl 5-hydroxyisophthalate and methyl chloroacetate. The title compound was synthesized via etherification and hydrazinolysis reactions under mild reaction conditions with high yield. The title compound was characterized by IR, 1HNMR and element analysis.