Synthesis And Properties Of Ions Responsive Smart Supramolecular Organogel

Based on the analysis of recent research progress at home and abroad in stimuli-responsive supramolecular organogel and our group’s research interest on ionresponsive supramolecular organogel, several series of low-molecular-weight supramolecular organic gelators were design and synthesized. The design strategies are as follows: three different kinds of self-assembly forces were rationally introduced to one molecule to obtain stable low concentration supramolecular gel based on multi self-assembly driving forces. These interactions include the Van der Waals’ force existing in the long alkyl chains, the π-π stacking interaction existing in the naphthalene and the multi-hydrogen bond of the aroyl hydrazone group. This kind of gelators have stronger binding abilities than those just have one self-assembly driving force. In addtion, to realize selective response for special ions, we rationally introduced the coordination binding sites to the molecule, which not only have the binding site with the target ions but also have acylhydrozone group acting as a hydrogen binding site. Conjugated fluorescent groups like naphthalene 、 hydroxy naphthalene、nitrobenzene were introduced to the molecules to achieve the fluorescent recognition of a certain ion. More important, the fluorescence signals and guest-selective responsiveness of the stimuli-responsive supramolecular gels( SRSGs)can be controlled by the competitive coordination of two different metal ions with the gelators and the target anion in the same gel system. In order to achieve selective fluorescence response for certain anions, we provide a novel design approach termed‘‘competitive coordination control AIE’’ mode to synthesize supramolecular gel-based chemosensors. Thus,a facile approach to the design of stimuli-responsive supramolecular gels(SRSGs) termed double-metal-ion competitive coordination control is reported. To demonstrate this approach, a gelator G1 based on multiple self-assembly driving forces was synthesized G1. G1 could form Ca2+-coordinated metallogel CaG1 with strong aggregation-induced emission(AIE). Doping of CaG1 with Cu2+results in AIE quenching of CaG1 and formation of Ca2+-and Cu2+-based metallogel CaCuG1. CaCuG1 could fluorescently detect CN- with specific selectivity through the competitive coordination of CN- with the Cu2+ and the coordination ofCa2+ with G1 again. Thus, CaCuG could act as a CN- test kit and could be utilised in rewritable security display materials. This approach may open up routes to novel stimuli-responsive supramolecular materials. Similarly, by rationally introducing Ca2+and Fe3+ into a supramolecular gel, a bimetal–gel CaFeG was prepared. CaFeG1 could reversibly ‘‘turn-on’’its fluorescence upon sensing H2PO4-with specific selectivity under gel–gel states through the competitive coordination of Ca2+ and Fe3+ with gelators and H2PO4-. Therefore, CaFeG1 could act not only as a H2PO4- test kit,but also an erasable security display material. On the other hand, we could control the anion response properties of metallogels by rationally introducing only one kind of metalion on metallogel. In view of this approach, the designed and synthesized gelator G2 can form Fe3+-based metallogel FeG2 by adding Fe3+to the gel. FeG2 could accurately fluorescence upon sensing CN-.