Tetraphenylfuran (TPF) and its control molecule tetraphenylthiophene (TPT), which are structurally similar to the aggregation-induced emission (AIE) active 2,3,4,5-tetraphenylsilole, were synthesized. Surprisingly, investigation of its photo-physical properties showed that TPF exhibits the aggregation-caused quenching effect instead of AIE characteristics, whereas TPT exhibits a quite weak AIE effect. Combining experimental results and theoretical calculations, this phenomenon was concluded to be co-caused by the restriction of intramolecular rotation (RIR), the mechanism of AIE, and the conjugation effect. Thus, this work provides an insight into RIR, which will greatly promote the development of AIE.

Photoactivatable probes for lipid droplets (LDs)-specific live-cell imaging are powerful tools for investigating their biological functions through precise spatial and temporal control. Ideal photoactivatable probes for LDs imaging require high concentration accumulation of fluorophores in LDs, simple synthetic procedures, and excellent photoactivation efficiency. However, it is difficult to overcome these challenges by conventional fluorophores due to aggregation-caused quenching (ACQ). In this study, a new class of photoactivatable and LDs-specific fluorescent probes was developed based on dihydro-2-azafluorenones, which can easily undergo photooxidative dehydrogenation reaction to afford 2-azafluorenones with aggregation-induced emission (AIE) properties. Dihydro-2-azafluorenones as photoactivatable and LDs-specific probes display significant advantages of excellent photoactivation efficiency and lack of self-quenching in the aggregated state, and are expected to have broad applications in study of biological functions of LDs' through light-controlled spatiotemporal imaging.

Super-sensitive and ultra-selective detection of explosives plays a crucial role in anti-terrorism operations, homeland security, civilian safety and environment protection. Among the developed fluorescent probes, the polymers with aggregation-induced emission (AIE) characteristics have drawn much attention due to their bright emission in the aggregate and solid states. However, no review has summarized the development of AIE-active polymers for explosive detection. Herein, we reviewed the recent progress on using AIE-active polymers to detect explosives with super-amplification quenching effect. Moreover, the challenges and opportunities in this area were also briefly discussed.

The hydroamination reaction of alkynes has been widely studied, but has not been developed as a powerful tool for polymer synthesis. Herein, a novel Cu(I)-catalyzed polyhydroamination has been developed for the facile preparation of nitrogen-containing polymers. This polymerization proceeded smoothly in bulk with 100% atom utilization in a regio-specific and stereo-selective fashion, producing polyenamines with well-defined structures and high molecular weights (up to 13 470) in high yields (up to 97%). Thus, this polymerization is a kind of amino-yne click polymerization. The resulting polymers possess excellent solubility, high thermal stability, strong UV-light shielding efficiency, and good visible light transparency. Considering the high efficiency, ready monomer availability and excellent performance of the products, this Cu(I)-catalyzed amino-yne click polymerization opens up enormous opportunities for preparing functional polymers.

Aggregation-induced emission (AIE) is a unique photo-physical phenomenon and has become an emerging and hot research area. With the enthusiastic efforts paid by researchers, hundreds of AIE-active luminogens (AIEgens) have been generated but heterocyclic AIEgens are rarely reported. Recently, we enriched the family of AIEgens and reported a pyrazine-based AIEgen of tetraphenylpyrazine (TPP), which could be facilely functionalized by a post-synthetic strategy. In this work, we further expanded the TPP-based AIE system by covalently attaching one, two or four electron-donating triphenylamine moieties to the TPP core via Suzuki coupling, and TPP–TPA, TPP–2TPA and TPP–4TPA were produced, respectively. Thanks to their donor-π-acceptor structures, these luminogens exhibit multi-functional properties, such as excellent thermal stability (up to 504 °C), large molar absorptivity, bright emission in the solid state (quantum yields up to 35.2%), solvatochromism, and high two-photon absorption cross-sections (up to 480 GM). Furthermore, using TPP–TPA as the emitting layer, a triple-layer device was fabricated and a turn-on voltage, maximum luminance, current efficiency, power efficiency, and external quantum efficiency of 3.7 V, 17 459 cd m−2, 5.49 cd A−1, 3.18 lm W−1 and 2.88% were realized, respectively. These results indicate a huge potential to develop high-tech applications based on these TPP-based AIEgens.

An air-stable supported Cu(I) catalyst, CuI@PS-Phen, was designed and synthesized. CuI@PS-Phen can efficiently catalyze the click polymerization of diynes a and diazides b to produce soluble and thermally stable polytriazoles with high molecular weights (M w up to 30800), and low copper residue content (down to 190 ppm) in high yields (up to 94.2%) under mild reaction conditions without the exclusion of oxygen.

Axial chiral aggregation-induced emission (AIE) luminogens of (R)-3,3′-BTPE-BINA, (R)-6,6′-BTPE-BINA and (S)-6,6′-BTPE-BINA were synthesized for the first time by covalently attaching the AIE-active tetraphenylethene (TPE) units to the axial chiral binaphthol (BINOL) moieties at their 3,3′- or 6,6′-positions. It was found that the circular dichroism (CD) value when TPE was attached to BINOL at its 3,3′-positions was much larger than that found after its attachment at 6,6′-positions. The resultant AIE-active luminogens (AIEgens) show high quantum yields (up to 42.4%) in their aggregated states. Interestingly, these AIEgens exhibit an abnormal aggregation-annihilation CD (AACD) phenomenon. The decrease in the twisted angle between the two naphthalene rings upon aggregation was rationalized as the cause of this unique effect.

Aromatic alkynes and azides were successfully polymerized under metal-free conditions using tetramethylammonium hydroxide (NMe4OH) as an organocatalyst at room temperature and soluble 1,5-regioregular polytriazoles P3a–P3e with high molecular weights (Mw up to 56 000) were readily produced in high yields (up to 96%).

The Cu(I)-catalyzed azide-alkyne click polymerization is well developed and broadly applied to the preparation of functional polymers. The removal of copper residues from the resultant polymers is, however, difficult. One way to completely circumvent this difficulty is to develop click polymerization without the use of metallic catalysts, i.e., metal-free click polymerization (MFCP). Herein, recent efforts towards developing MFCP of activated alkynes and azides, and of activated azides and alkynes, to produce regioregular polytriazoles are summarized, and the properties and applications of the resultant polymers are also briefly discussed.

The “thio-click” polymerization is a well-expanded concept of click polymerization. Among the click polymerizations, the thiol–yne click polymerization is less developed and still in its infancy stage. In general, UV light, elevated temperature, amine, or transition metal complexes is needed to catalyze the thiol–yne click polymerization, which greatly complicates the experimental operation and limits its application. In this work, a facile and powerful thiol–yne click polymerization was developed, which could be carried out under very mild conditions without using external catalyst. Simply mixing the aromatic diynes (1a–1e) and dithiols (2–4) with equivalent molar ratio in THF at 30 °C will readily produce soluble and regioregular functional poly(vinylene sulfide)s (PIa–PIe, PII, and PIII) with high molecular weights (Mw up to 85 200) in excellent yields (up to 97%) after as short as 2 h. Furthermore, no double addition product of an ethynyl group was found. This catalyst-free thiol–yne click polymerization has remarkably simplified the reaction conditions and will facilitate the preparation of functional materials applied in diverse areas.