An acylhydrazone-based colorimetric and fluorescent sensor (PAH-8) for the detection of F⁻ and TFA/TEA has been studied. PAH-8 solution and organogel are highly selective and sensitive to F⁻ among various tested anions in DMSO.

Introduction of a central benzene ring could increase the charge transferred distance, and further contribute to the enhancement of the intramolecular charge transfer strength.

A new triphenylamine-based acylhydrazone derivative (TPAH-B8) was synthesized. TPAH-B8 could form organogels in cyclohexane through ultrasonic treatment. A typical gelation-induced fluorescence enhancement property was observed, which was attributed to the formation of J-aggregate in the gel state. More interestingly, TPAH-B8 exhibited multistimuli responsive behaviors. First, TPAH-B8 showed a solvatochromic effect, with the emission color changing from blue to cyan with the change in solvent from nonpolar cyclohexane to polar dimethyl sulfoxide (DMSO). Second, TPAH-B8 showed a reversible mechanofluorochromism. The xerogel of TPAH-B8 emitted a blue fluorescence, while the fluorescence color changed to cyan after grinding. The cyan and blue colors could be repeated with the treatment of grinding and annealing, which was explored and ascribed to the transformation between crystalline and amorphous states. Third, TPAH-B8 revealed acidochromic property. The fluorescence color of TPAH-B8 in organogel and solid states could be switched by trifluoroacetic acid (TFA)/triethylamine (TEA). This work not only demonstrated the multistimuli-responsive fluorescent properties of TPAH-B8 but also offered an easy way to develop new kinds of multistimuli-responsive fluorescent materials.

We have demonstrated ultrasound-induced organogels based on twin-tapered dihydrazide derivatives, oxalyl acid N,N-di(3,4,5-trialkoxybenzoyl)hydrazide (FH-Tn). Ultrasound irradiation has been proved to influence gel properties at micro-levels. Different self-assembled structures from entangled fibers to tube-like structures and nanoparticles can be easily manipulated by tuning irradiation time and water bath temperature. FT-IR spectra exhibit weakened hydrogen bonding interactions, and XRD studies showed different packing modes before and after sonication. In addition, ultrasound can have effects on gel properties at macro-levels. Gels obtained from ultrasound treatment possess different wetting properties, relatively worse rheological properties and thermo-stability. Kinetic studies based on dynamic fluorescence spectra, rheological studies and theoretical calculations suggest that molecular aggregation mode differed from one-dimension to two-dimension for the gel after sonication.