Tunable AIEE fluorescence constructed from a triphenylamine luminogen containing quinoline - application in a reversible and tunable pH sensor

Novel A–D–A structural imidazole derivatives with charge transfer excited states: importance of molecular structure design in obtaining a “turn-on” type fluorescence probe

Two A–D–A structural triphenylamine-imidazole derivatives were designed to provide a potential strategy for the development of turn-on type Fe3+ fluorescent probes.

Solid-State Fluorescence of A Quasi-Isostructural Polymorphic Biphenyl Based Michael Addition Product

Polymorphic materials have gained significant attention owing to their fascinating physicochemical properties. Herein, a biphenyl based Michael addition product (Compound A) with an active methylene group (dimedone) was synthesized. Compound...

Visual detection of viscosity through activatable molecular rotor with aggregation-induced emission

Food safety has become one of the urgent affairs in the global public health studies, and irregular viscosity is closely associated with the food spoilage extent. In this study, one kind of activatable molecular rotor (TPA-PBZ) based on triphenylamine derivates has been synthesized via the Schiff base condensation reaction. This rotor is comprised by donor-accepter conjugated structure, with aggregation induced-emission feature and a large Stokes shift of 160 nm in water. The rotation of aromatic rings in TPA-PBZ is restricted in high-viscosity microenvironment, with the gradually increasing fluorescence emission signal at 568 nm. Significantly, this rotor TPA-PBZ has successfully been applied not only in the determination of thickening effects of food gum, but also in the detection of viscosity enhancement during the liquid food spoilage process. This molecular rotor can be utilized as an intelligent monitor platform for food quality and safety inspection in viscosity-related conditions.

Aggregation-induced Emission Properties of Triphenylamine Chalcone Compounds

Two triphenylamine chalcone derivatives 1 and 2 were synthesized through the Vilsmeier-Haack reaction and Claisen-Schmidt condensation reaction. Through ultraviolet absorption spectroscopy and fluorescence emission spectroscopy experiments, it was confirmed that these two compounds exhibited good aggregation-induced emission (AIE) behavior in ethanol/water mixtures. The solvent effect test showed with the increase of the orientation polarizability of the solvent, the Stokes shift in the solvent of compound 1 and compound 2 shows a linear change trend. Through solid state fluorescence test and universal density function theory (DFT), the existence of π-π stacking interaction in the solid state of the compound has been studied, resulting in weak fluorescence emission. pH has no effect on the fluorescence intensity of the aggregate state of excited state intramolecular proton transfer (ESIPT) molecules in an acidic environment, but greatly weakens its fluorescence intensity in an alkaline environment. Cyclic voltammetry (CV) test shows that compound 1 was more prone to oxidation reaction than compound 2. The results of thermal stability test show that the thermal stability of compound 1 was better than that of compound 2, indicating that triphenylamine chalcone derivatives can improve the thermal stability of compounds by increasing the number of branches.

A Versatile Aggregation-induced Emission Fluorescent Probe for Visible Detection of pH

By tactfully structuring a luminescent molecule as an accurate pH probe with aggregation-induced emission (AIE) feature, it is significant to overcome aggregation-caused quenching of emitted light in practice. Herein, we present a simple AIE-active fluorescence probe for pH detection on the basis of intramolecular charge transfer (ICT) with wide response range and high sensitivity reaction. The donor-acceptor-donor (D-A-D) style probe utilized a conjugated structural hybrid of the electron-withdrawing nitrile group and electron-donating hydroxyl as well as dimethylamino groups for fluorescent platform. The AIE-active probe possesses good fluorescence under water fraction up to 90% in mixed MeOH/water system. Furthermore, it can be used in profiling and visualization of pH detection in MeOH/water system at f_w = 90% under UV 365 nm lamp. What's more, the probe can be employed to be a broad range test paper of pH detection, paving the way for low-cost practical applications.

Comparative study of the photophysical and crystallographic properties of 4-(9H-pyreno[4,5-d]imidazol-10-yl)phenol and its alkylated derivatives

The photophysical and crystallographic properties of a para-hydroxphenyl-substituted pyrenoimidazole and its decylated analogues were investigated. The fluorescence of these compounds is sensitive to environmental acidity and basicity.

Two AIEE-active α-cyanostilbene derivatives containing BF2 unit for detecting explosive picric acid in aqueous medium

Two novel α-cyanostilbene derivatives bearing triphenylamine and BF₂ groups are synthesized (named TPE-B and TPE-BN). The fluorescent emissions of compounds TPE-B and TPE-BN are hypochromatically shifted and bathochromically shifted, respectively, with increasing polarity of the solvents, suggesting that the two compounds have characteristic polarity-dependent solvatochromic effects. Furthermore, they show obvious aggregation-induced emission enhancement (AIEE) phenomenon in THF/water mixture solutions. Meanwhile, compounds TPE-B and TPE-BN emit orange and yellow fluorescence in their solid states, respectively. Most significantly, in aqueous medium, compounds TPE-B and TPE-BN can selectively and sensitively detect picric acid (PA) among a number of nitroaromatic compounds, and their limits of detection (LOD) are calculated as 1.26 × 10⁻⁶ M and 1.51 × 10⁻⁶ M, respectively. The recognition mechanism for PA can be attributed to the photo-induced electron transfer (PET) process and this is supported by density functional theory (DFT) calculation. This research provides two novel compounds for the rational design of AIEE-active materials for sensing systems.

Two α-cyanostilbene derivatives bearing triphenylamine and BF₂ groups exhibit AIEE properties and can detect explosive picric acid in aqueous medium.

Multi-stimuli responsive properties switch by intra- and inter-molecular charge transfer constructed from triphenylamine derivative

The compound TPA-BI exhibited multi-responsive fluorescence behaviors caused by inter-molecular charge transfer (CT) and intra-molecular CT formation.

A novel carbazole derivative containing fluorobenzene unit: aggregation-induced fluorescence emission, polymorphism, mechanochromism and non-reversible thermo-stimulus fluorescence

Different conformations and packing modes induce the compound with unique stimuli-responsive properties.