CCS Chemistry最新文献

Novel carbon allotropes have long been pursued in synthetic chemistry and materials science, and graphene has been the most well-investigated carbon nanostructure in the past decade. However, an analogous carbon pentaheptite with equal numbers of pentagons and heptagons has not yet been synthesized because designing and synthesizing nonhexagon motifs along two dimensions is challenging. During the synthesis of a pentaheptite substructure (or named nanopentaheptite, NPH), which contain four pentagon-heptagon pairs and one heptalene unit, unexpected cyclopenta[ef]heptalene-into-phenanthrene rearrangements were observed for the first time, yielding two novel compounds (NPH-R1 and NPH-R2). Experimental and theoretical results demonstrated that the NPH series exhibits narrower energy gaps than that of their hexagonal analog with similar size (e.g., hexa-peri-hexabenzocoronene, HBC). Our work reported herein, based on the azulene chemistry, provides new insights into the preparation of novel carbon allotrope pentaheptite nanostructures.

Currently, there is no versatile method for the synthesis of high molecular weight (MW) polymers by controlled radical polymerization from a broad range of monomers using a single agent. Herein, we report a universal photoiniferter reversible addition-fragmentation chain transfer (RAFT) polymerization formulation using a suitable pyrazole-based chain transfer agent (CTA) combined with blue light irradiation. Well-controlled polymerization was observed for methyl methacrylate (MMA), methyl acrylate (MA), N,N-dimethylacrylamide (DMA), and N-vinylpyrrolidone (NVP). High polymerization rates were achieved, attributed to the high molar absorption coefficient of the pyrazole-based CTA and its rapid rate of photolysis. Poly(methyl acrylate) (PMA) and poly(N,N-dimethylacrylamide) (PDMA) syntheses yielded low-dispersity ultrahigh MW chains (>10⁶ g mol⁻¹, Р< 1.3). High end-group fidelity enabled the preparation of well-defined high MW diblock copolymers comprising both more activated and less activated monomers, including PDMA-b-PNVP and PMA-b-PNVP. Such syntheses demonstrated that visible light-mediated photoiniferter RAFT polymerization conducted using pyrazole-based CTAs was both highly efficient and versatile.

The fabrication of liquid-free ionic conductive elastomers (ICEs) that can function as flexible temperature sensors with high sensitivity, fast response time, and efficient recyclability is a great challenge. In this study, novel liquid-free ICEs are conveniently fabricated through the complexation of 4-carboxybenzaldehyde-grafted poly(vinyl alcohol) (CPVA) with well-designed solid quaternary ammonium (QA) molecules bearing bifunctional hydrogen-bonding moieties. The resulting CPVA-QA elastomers, which are highly elastic and adhesive to diverse surfaces, exhibit a tensile strength of 6.6 MPa, a toughness of 14.7 MJ m⁻³, and a Young’s modulus of 0.15 MPa. These elastomers have a hydrogen-bonded network structure where the bifunctional QA molecules significantly suppress polymer chain entanglements. Benefitting from the thermally sensitive hydrogen bonds and the substantially reduced chain entanglements, the CPVA-QA elastomers show a high chain mobility upon temperature elevation, which facilitates ion transport within the CPVA-QA elastomers. Consequently, the CPVA-QA elastomer-based temperature sensors show an outstanding temperature resolution (0.05 °C), a fast response time over a wide temperature range, and a record-high thermosensitivity of 10.8% K⁻¹. Importantly, the CPVA-QA sensors can be depolymerized under mild conditions to recover their original components in high purity and yields (>96%), enabling closed-loop recycling of the sensors.

For studies concerning circularly polarized multiple resonances thermally activated delayed fluorescence (CP-MR-TADF) emitters with central chirality, only carbon element has been applied. Herein, for the first time, we report a CP-MR-TADF material with phosphorus central chirality containing tert-butyl(phenyl)phosphine oxide, (R/S)-4-POtBuCzB, as enantiomers exhibiting the narrowest full-width at half-maximum (FWHM = 20 nm) among the reported CP-TADF molecules, with symmetric CP photoluminescence and a dissymmetry factor (|g_PL|) of 0.54 × 10⁻³. Concurrently, 2-POtBuCzB further demonstrated that phosphine participated in photophysical performance regulation. Notably, CP organic light-emitting diodes (CP-OLEDs) using (R/S)-4-POtBuCzB showed remarkable CPEL activity with a |g_EL| of 0.61 × 10⁻³, and OLED with 2-POtBuCzB, achieving a maximum external quantum efficiency (EQE_max) of 37.0%. These results demonstrate that introducing chiral phosphorus fragments into the MR-TADF skeleton is an efficacious approach for CP-MR-TADF materials and devices.