Temperature-, Solvent-and Anion-responsive Fluorescent Organogel

Low molecular mass organogels (LMMGs) have attracted significant attentionsdue to their potential application. In general, the driving force of the gel formation isthe intermolecular weak interactions, such as π-π interaction, van der Waals forceand intermolecular hydrogen bond etc. There are obvious changes in physical andchemical properties after phase transition from gel to sol state. Such phase transitioncould be caused by physical (agitation, ultrasound, light, magnetic field, etc) andchemical (redox, anionic, cationic and so on) stimuli. Such gels are known to bestimuli-responsive gel.In this thesis, we have focused on the construction of stimuli-responsiveLMMGs. Some series of gelators with cyanostyrene were designed and synthesized.Their self-assembling and photophysical properties in gels were investigated. Thesensing behaviors of gels towards temperature and anions were also examined. Theobtained results are as follows:1. Four series of cyanostyrene derivatives containing carbazole, phenothiazineand phenyl moieties have been synthesized. The tests of their gelation abilitiessuggested that only phenothiazine-based cyanostyrene derivatives could notgelatinize any selected solvents, but carbazole and phenyl derivatives could form gelin alcohols, alkanes or DMSO. Spectral results indicated that π-π interaction and vander Waals force were the main driving forces for the gel formation, and the nitrogroup played an important role on the gelation process. Three series of gelatorsformed J-aggregates in gel phases, which induced gelation-induced enhancedemission and different colors in sol and gel phases change.2. A cyanostyrene derivatives containing glutamine group have beensynthesized. It was found that it could form gel in DMSO, DMF, mesitylene, anisoleand o-dichlorobenzene, etc. Spectral results indicated that the main driving forces for the gel formation were the H-bonding and π-π interaction. Moreover, thephotophysical properties of this gelator in gel strongly depended on the polarity ofsolvent. The gel could be converted into sol upon the addition anions, accompaniedby obvious changes in color and fluorescence. In addition, solvent could affect theanion-responsive behaviors of gels. DMSO gel could respond to three kinds ofanions, ODCB gel could have a response only to Fˉ.