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A CsCu2I3 SA-based passively mode-locking fiber laser was demonstrated. The fiber laser could operate stably for at least five months, which will potentially unlock the pathways for ultrafast photonics based on lead-free halide perovskites.

Tantalum disulfide (TaS2), an emerging group VB transition metal dichalcogenide, with unique layered structure, rich phase diagrams, metallic behavior, higher carrier concentration and mobility is emerging as a prototype for revealing basic physical phenomena and developing practical applications. However, its photonics properties and even engineering-related processes are still rare. Here, the top-down experiment demonstration, including synthesis, thickness optimization and nonlinear optical application, has been reported. In addition, the ultrafast (∼373 fs) erbium-doped fiber pulse with a small time-bandwidth product (∼0.34) and long-term stability (∼25 days) was realized using the nonlinear absorption properties of the high-quality 2H-TaS2 nanosheet. These results suggest an experimental route for further ultrafast photonics exploration based on metallic transition metal dichalcogenides.

The development of new polymerization reactions conducted under monomer non-stoichiometric conditions has great academic and industrial significance. Herein we report such a new route for synthesizing functional polynaphthalenes (PNs). The polycoupling reactions of benzoic acid and its derivatives (1) with 4,4′-(1,6-hexylenedioxy)bis(diphenylacetylene) (2) proceed smoothly in o-xylene in the presence of [Cp*IrCl2]2 and Ag2CO3 at 140 °C, generating multisubstituted PNs with high molecular weights (Mw up to 228 700) in high yields (up to 98%). The effect of monomer stoichiometry on the polymerization was systematically investigated and the best result was obtained at a molar feed ratio of 1 : 2 of 2 : 1. The associated mechanism for the monomer non-stoichiometry enhancement effect was proposed. All the obtained PNs show good thermal stability and excellent optical transparency. They possess good film-forming ability and their thin films exhibit high refractive indices (n = 1.7653–1.6354). Polymers constructed from non-emissive monomers show light emission in solutions due to the generation of fluorophores in situ during the polymerization. The polymer carrying a tetraphenylethene motif is weakly emissive in solution but emits intensely when aggregated, demonstrating a phenomenon of aggregation-induced emission. The efficient solid-state emission and good photosensitivity enable it to be utilized as a material for fabricating two-dimensional fluorescent photopatterns by irradiating its thin films under UV light through copper masks.

A bioprobe, TPE-Zn2BDPA, with aggregation-induced emission characteristics was designed and synthesized to differentiate the early and late stages of apoptosis mediated by H2O2. TPE-Zn2BDPA does not respond to healthy cells, but it selectively lights up the membrane of apopotic cells in both stages with brighter fluorescence in the late apoptotic stage.

An atom-economical and straightforward polymerization method to generate functional isocoumarin-containing polymers was developed in this work. The oxidative polycoupling of 4,4′-(1,2-diphenyl-1,2-ethenylene)dibenzoic acid and 1,6-bis[4-(phenylethynyl)phenoxy]hexane proceeds efficiently in dimethylformamide under nitrogen or air in the presence of [Cp*RhCl2]2 and a catalytic amount of Cu(OAc)2·H2O at 120 °C for 24 h, generating a polymer with a high molecular weight of up to 42 900 in a high yield of up to 92.9%. An isocoumarin framework forms in situ during the polymerization from readily accessible and inexpensive monomers. The resulting polymer possesses good thermal stability, optical transparency and film-forming ability. Its thin film exhibits high and UV-tunable refractive indices (n = 1.9697–1.6507) in a wide wavelength region of 390–890 nm. A two-dimensional fluorescent photopattern can be readily fabricated by irradiating its thin film under UV light through a copper mask. Due to the incorporation of tetraphenylethene units in the monomer, the polymer obtained is weakly emissive in solution but it emits intensely when aggregated, demonstrating a phenomenon of aggregation-induced emission.

Green chemistry shows the advantages of a simple synthetic process, low cost of production, a clean working environment and reduction of harmful wastes. In this work, we used naturally occurring materials to prepare functional polymers. The polymerizations of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene, disulfonyl azide, and water together with ethanol were catalyzed by copper(I) iodide and triethylamine in a mild, efficient and atom-economical fashion, generating soluble polymers with high molecular weights in satisfactory isolation yields. By controlling the adding amount of water and ethanol, the ratio of amide and imidate units in the polymer chain could be readily modulated. Their good solubility allows the polymers to show outstanding film-forming ability. Due to the tetraphenylethene moieties embedded in the polymer chains, the polymer solutions emit faintly, but their aggregates fluoresce intensely, demonstrating a characteristic of aggregation-induced emission. Such results are anticipated to accelerate the development of efficient and economical one-pot multicomponent polymerizations toward functional polymeric materials.

Multicomponent sequential reactions have recently received much attention owing to their outstanding advantages, such as simple operation, atom economy, and environmental benefit. In this work, we report a new multicomponent sequential reaction and the corresponding multicomponent sequential polymerization approach to construct conjugated structures with advanced functionalities. By employing 1,8-diazabicyclo[5.4.0]undec-7-ene as an additive, alkynes, carbonyl chloride and amino ester salts undergo a one-pot three-component sequential reaction successfully. Similarly, the derived multicomponent sequential polymerizations of diyne, terephthaloyl chloride and amino ester proceed smoothly in a regio- and stereoregular manner and generate conjugated nitrogen-substituted poly(enaminone)s with high molecular weights in satisfactory yields. All the resulting polymers are soluble in common solvents, and possess high thermal stability and good film-forming ability. Interestingly, the incorporation of optically active chiral amino esters as pendants leads to polymeric products with helical rotating backbones, as revealed by their circular dichroism spectra in the solutions and as cast films. With fluorescent tetraphenylethene moieties embedded in the polymer chains, the polymers display a phenomenon of aggregation-enhanced emission. They emit weakly in the solution state, but fluoresce intensely as aggregates. Moreover, the thin films of the polymers exhibit high light refractivity (n = 1.9305–1.5992) in a wide wavelength region (400–1000 nm), which can be readily modulated by UV irradiation. Additionally, the polymeric products with photosensitivity can generate highly resolved two-dimensional luminescent patterns by UV treatment.

The development of an efficient transition metal-free polymerization route has been an active research topic in polymer science owing to its low synthetic cost and decreased metal residue and hence elevated material performance in the products. In this work, we report a new such method for constructing conjugated polydiynes based on the organic reaction of 1-haloalkyne. In the presence of potassium iodide, the polymerizations of 1,2-bis[4-(iodoethynyl)phenyl]-1,2-diphenylethene (1), 1,4-bis(2-iodoethynyl)benzene (2) and 4,4′-bis(2-iodoethynyl)-1,1′-biphenyl (3) proceed smoothly in N,N-dimethylformamide at 120 °C under nitrogen, producing P1–3 consisting of alternate aromatic and 1,3-diyne moieties in moderate to satisfactory yields. While P1 possesses good solubility in common organic solvents, P2 and P3 are insoluble due to their rigid structures. All the polymers are thermally stable, losing 5% of their weight at a high temperature of up to 352 °C. A homogeneous film of P1 can be readily obtained by spin-coating its solution, which shows high and UV-tunable refractive index (n = 2.1125–1.7747) in a wide wavelength range (400–900 nm). A well-defined fluorescent photopattern can be generated by UV irradiation of the polymer film through a copper mask. This work thus opens a new avenue for constructing conjugated polymers with advanced functionalities.

A metal-free, multicomponent polymerization route for the facile construction of stereoregular functional polymers has been developed in this work. Boron trichloride-mediated polycoupling of terminal diynes and monoaldehydes was carried out in a stereoselective manner in dichloromethane under mild conditions and nitrogen, affording poly(dichloro pentadiene)s (PDPDs) with a predominant (E,Z)-configuration in high yields (up to 92%) with high molecular weights (Mw up to 174300) in several hours. All the polymers possessed good solubility in common organic solvents and showed high thermal stability, losing merely 5% of their weight at high temperatures of up to 384 °C. PDPDs carrying tetraphenylethylene (TPE) moieties exhibited a unique photophysical phenomenon of aggregation-induced emission (AIE): the emission of their weakly emissive solutions was turned on upon aggregation formation. Thin solid films of the polymers with good quality were readily fabricated on silica substrates by a simple spin-coating technique, and showed pretty high refractive indices (RI = 1.7937–1.4873) in a wide wavelength region of 400–890 nm. The PDPDs are photosensitive and such a property enables them to be promising materials for fabricating fluorescence patterns by the photolithography process.

Herein we reported a new facile one-pot multicomponent sequential polymerization approach for the construction of conjugated nitrogen-substituted polymers. Catalyzed by Pd(PPh3)2Cl2/CuI at room temperature, the coupling-hydroamination polymerizations of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene, terephthaloyl chloride and secondary aliphatic amines proceeded smoothly in a regioregular and stereoselective manner, furnishing poly(arylene enaminone)s (PAEs) with high molecular weights (Mw up to 34 600) in satisfactory yields (up to 91%). A model compound was elaborately designed and synthesized to verify the chemical structures of the corresponding polymeric products. All the PAEs exhibited good solubility in common organic solvents and were thermally stable with degradation temperatures of up to 313 °C under nitrogen. They possessed good film-forming ability and their thin solid films showed high refractive indices (RI = 1.9318–1.6320) in a wide wavelength region of 400–1000 nm, whose value could be further modulated by UV irradiation. Although the model compound and the PAEs possessed a typical aggregation-induced emission luminogen of tetraphenylethene, they were weakly emissive either in solution or in the aggregated state, due to the photoinduced electron transfer (PET) effect. Their strong emission in the aggregated state could be readily recovered by the blockage of the PET effect through protonation of the amino groups. Thus, this work demonstrated a powerful polymerization tool to access conjugated polymeric materials with pH-responsive properties.

Self-assembling of luminescent molecules into one-dimensional nanostructures is of particular interest in fabricating nanoscale electronic and photonic devices. Herein, we report the rational design and synthesis of a chiral fluorescent tetraphenylethylene derivative containing L-leucine methyl ester moiety (TPE-Leu). In solution, TPE-Leu is non-emissive and CD silent, but becomes highly emissive and CD active upon aggregation, exhibiting aggregation-induced emission (AIE) and chirality (AIC). Upon evaporation of its solution, TPE-Leu readily self-assembles into helical fluorescent micro/nanofibers, which show circularly polarized luminescence (CPL) and have the CPL dissymmetry factors in the range of 0.02–0.07. This molecular design combines the AIE effect, chirality, and self-assembling capability together, and is highly efficient in constructing novel functional micro/nanomaterials with well-defined structures and enhanced emission.

Polyhydroaminations for the synthesis of stable nitrogen-substituted conjugated polymers with well-defined structures remain a great challenge and the control of the regio- and stereochemistry of the enamine product of the hydroamination is non-trivial. Herein we report an efficient tandem polymerization of alkynes, carbonyl chlorides and primary amines to afford regio- and stereoregular conjugated poly(enaminone)s. The atom-economical one-pot sequential polycoupling–hydroamination polymerization catalyzed by Pd(PPh3)2Cl2/CuI proceeded smoothly under mild conditions, furnishing nitrogen-substituted conjugated polymers with high molecular weights (up to 46 100) and high regio-/stereoregularities (100%) in nearly quantitative yields (up to 99%). The single crystal structure of the model compound, together with the NMR spectra comparison of the model compound and polymers provided direct insight into the stereoselectivity of the polymerization, verifying the sole Z-vinylene isomer of the polymers. Through the exquisite structural design strategy of the intramolecular hydrogen bond of the resulting hydroamination product, the tautomerization between enamine and imine as well as E/Z isomerization was successfully avoided, providing products with high chemical stability and sole Z-vinylene isomers. The conjugated polymers display excellent solubility in common organic solvents, good film-forming ability, and high thermal stability. The hydrogen bond formation of the polymer helps to block the potential photo-induced electron transfer process and the polymer shows a unique aggregation-enhanced emission phenomenon: their solutions are weakly emissive, while their nanoaggregates or thin films are brightly emissive. Furthermore, thin films of the polymers enjoy high refractive indices (1.9103–1.6582) in a wide wavelength region of 400–1000 nm, which can be further modulated by UV irradiation. Meanwhile, well-resolved fluorescent photopatterns of the polymers can be fabricated through the UV irradiation of thin films via a copper photomask.

The self-assembly of fluorescent molecules is of general interest due to the potential fabrication of nanostructured materials. The fabrication of fluorescent nanowires remains challenging because the inherent aggregation in the self-assembly process quenches the fluorescence of the molecules in many cases. In this work, new aggregation-induced emission-active tetraphenylethene derivatives were used to fabricate fluorescent nanowires facilely by self-assembly processes. Moreover, the fluorescent nanowires can further self-assemble to form macroscopic fluorescent thin films in the solution. The detailed self-assembly processes from nanospheres to nanowires, and further to fluorescent macroscopic thin films were elucidated and evidenced by SEM imaging. A phenomenon of photo-induced emission enhancement was observed, owing to the photo-induced ring-closing oxidative reaction of the tetraphenylethene core.