Synthesis of organogelators with AIE characteristics and their reversible acid/base response properties
Two coumarin organogelators with aggregation-induced emission(AIE)characteristics,cou-C8b and cou-C10b,were synthesized.They can form stable gels in several alcoholic solvents(such as ethanol,isopropanol and tert-amyl alcohol)and acetone,and multiple cycle transitions of sol-gel can be achieved by heating-cooling treatment.The Fourier transform infrared spectroscopy(FT-IR),X-ray dif-fraction(XRD),scanning electron microscope(SEM)and concentration-dependent 1H NMR indicated that hydrogen bonds,π-π interactions and van der Waals forces promoted the self-assembly process.The optical properties of two organogelators were studied by UV-Vis absorption spectra and fluorescence spec-tra,and it was indicated that the hot sol states exhibited almost none or very weak fluorescence,while the gel states appeared strong yellow fluorescence after cooling,showing an obvious AIE effect.Furthermore,the theoretical calculation indicated that the AIE effect may be due to the intermolecular non-covalent in-teractions which caused the restriction of the intramolecular motions(RIMs).In addition,these two or-ganogels showed reversible acid/base response properties,after the addition of NaOH solution,the gel structures collapsed and showed bright cyan-blue fluorescence,while the samples can restore gels again and recover the original yellow fluorescence with the addition of HCl solution.This result indicates that this type of organogelators has the potential application value in the manufacture of light-emitting nano-structured devices.