Search

A polymeric heterojunction hybrid composed of a C6-FDTP conjugated polymer and graphitic carbon nitride via π–π interactions exhibits superior photocatalytic hydrogen generation under visible light irradiation.

AIE/AIEE-active conjugated polymers have shown great potential in bioimaging applications. However, the absorption of many AIE/AIEE polymers poorly matches with the laser excitation used in confocal imaging, which may greatly affect the imaging quality. In this regard, we designed and synthesized a novel conjugated polymer incorporating π-extended boron ketoiminate units. The resulting polymer shows typical aggregation-induced enhanced emission (AIEE) characteristics and a dominant UV absorption of 447 nm in THF, which matches well with the laser excitation. Moreover, the polymer exhibits a Stokes shift up to 100 nm, which makes it a good candidate for cell imaging applications. The polymer was subsequently encapsulated into amphiphilic poly(styrene-co-maleic anhydride) (PSMA) to yield conjugated polymer nanoparticles (CPNs) (∼65 nm), which can emit bright yellow fluorescence in aqueous media with a quantum yield of 15%. Meanwhile, the HeLa cell imaging results demonstrate that the CPNs exhibit low cytotoxicity and high photostability, which are good contrast agents for biological fluorescence imaging.

Conjugated polymers have recently been under active investigation as promising alternatives to traditional inorganic semiconductors for photocatalysis. This is due to their unique advantages of low cost, high chemical stability, and molecularly tunable optoelectronic properties. This critical review summarizes the recent advancements in π-conjugated polymers for visible-light-driven photocatalytic applications including water splitting, CO2 reduction, organic transformation and degradation of organic dyes. Special emphasis is placed on how the changes in the polymer structure could influence their physicochemical properties and photocatalytic activities. This structure–activity relationship analysis should guide rational molecular design of conjugated polymers for improved photocatalytic activity.

A gradient cobalt-doped MgIn2S4 (MgIn2S4-Co) homojunction photocatalyst was reported, creating an oriented built-in electric field for efficient extraction of photogenerated carriers from the inside to the surface of the photocatalyst. The MgIn2S4-Co photocatalysts showed remarkably enhanced photocatalytic CO2 reduction activity compared with pristine MgIn2S4.

Organic π-conjugated polymers (CPs) have been intensively explored for a variety of critical photocatalytic applications in the past few years. Nevertheless, CPs for efficient CO2 photoreduction have been rarely reported, which is mainly due to the lack of suitable polymers with sufficient solar light harvesting ability, appropriate energy level alignment and good activity and selectivity in multi-electron-transfer photoreduction of CO2 reaction. We report here the rational design and synthesis of two novel triphenylamine (TPA) based conjugated microporous polymers (CMPs), which can efficiently catalyze the reduction of CO2 to CO using water vapor as an electron donor under ambient conditions without adding any co-catalyst. Nearly 100% selectivity and a high CO production rate of 37.15 μmol h−1 g−1 are obtained for OXD-TPA, which is significantly better than that for BP-TPA (0.9 μmol h−1 g−1) as a result of co-monomer change from biphenyl to 2,5-diphenyl-1,3,4-oxadiazole. This difference could be mainly ascribed to the synergistic effect of a decreased optical band gap, improved interface charge transfer and increased CO2 uptake for OXD-TPA. This contribution is expected to spur further interest in the rational design of porous conjugated polymers for CO2 photoreduction. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Binary metal oxides have been considered as promising anode materials, which exhibit much better performances than single metal oxides in view of their variable oxidation state and fairly high electrical conductivity. In this research, NiCo2O4 nanocrystals are prepared from a facile procedure including microemulsion-solvothermal reaction and subsequent calcination at 400 °C for 4 hours. The as-prepared NiCo2O4 nanocrystals are characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). When applied as an anode for a lithium ion battery, it demonstrates excellent cycling and rate stability. The initial charge/discharge efficiency is as high as 75.41% at a current density of 100 mA g−1. After 45 cycles, the discharge capacity still retains up to 1175.9 mA h g−1, which is even much higher than that of the initial discharge capacity. Meanwhile, the reversible capacity remains over 644.9 mA h g−1 at a large current density of 1600 mA g−1, ascribed to the dispersed nanoparticles, which will help to improve the conductivity of the electrode material during the lithium-ion insertion/deintercalation process, shorten the ion diffusion path and reduce the charge transfer resistance (Rct).

In this study, four boron ketoiminate-based conjugated polymers P1–P4 are designed and synthesized via Suzuki polymerization. The resulting polymers are weakly fluorescent in pure THF solutions, but become highly emissive when aggregated in THF/water mixtures or fabricated into conjugated polymer nanoparticles (CPNs), showing typical AIE (AIEE) behaviors. CPNs from P1–P4 could be prepared by reprecipitation with the particle size ranging from 85 to 95 nm. Interestingly, the tuning of the emission color of P1–P4 nanoparticles (NPs) could be conveniently accomplished by varying the substituent in the phenyl ring, which can be ascribed to the donor–acceptor interaction between the substituted phenyl ring and the boron chelating ring. The DFT theoretical calculation of the polymer repeating units indicates that the band gaps of P1–P4 can be tuned in the range 2.72–3.40 eV, suggesting that substituents in the polymer backbone have a great influence on their electronic structures and thus change AIE (AIEE) properties. Furthermore, all of the four CPNs with low cytotoxicity and high photostability could be further employed for HeLa cell imaging.

A novel chiral conjugated polymer is developed and used for the preparation of conjugated polymer nanoparticles (CPNs) with particle sizes ranging from 80 to 190 nm. The size-dependent optical properties of chiral CPNs are fully studied and it was found that the nanoparticles exhibited a prominent red shift both in UV-vis and fluorescence emission with increasing diameters. The circular dichroism (CD) spectra and anisotropy r values of the CPNs display size-tunable chirality features, which can be attributed to the nature of the aggregates as nanoparticles grow. Meanwhile, the obtained CPNs can serve as efficient far-red/near-infrared (FR/NIR) fluorescent probes with low cytotoxicity and high photostability for HeLa cell imaging.

Two AIE-active chiral BINOL-based O-BODIPY enantiomers (R/S-5) were synthesized and showed mirror-image red-color CPL induced via intramolecular energy transfer. The chiroptical properties of the molecules indicate that the chirality of electronic ground and excited states is stable and independent of aggregation.

Herein we report a one-pot deoxygenation protocol for primary and secondary alcohols developed via the combination of the Garegg-Samuelsson reaction, visible light-photoredox catalysis, and flow chemistry. This procedure is characterized by mild reaction conditions, easy-to-handle reactants and reagents, excellent functional group tolerance, and good yields.

A new approach to anhydride formation is reported via activation of C-O bonds by the Vilsmeier-Haack reagent formed by Ru(bpy)(3)Cl(2) and CBr(4) in DMF. Various aryl and alkyl carboxylic acids are converted to the corresponding anhydrides in excellent yields.