Xinhua Wan

The asymmetric kinetic resolution polymerization (AKRP) of racemic diazoacetates mediated by a [Rh(cod)Cl]2/chiral amine dual catalyst system exhibits dynamic nonlinear effects (DNLEs) in the relative rate constant (Krel). The overall Krel increases nonlinearly with the monomer conversion during polymer chain propagation and reaches a plateau at a medium conversion. These DNLEs originate from synergistic chirality amplification between the catalytic chain end and the evolving helical conformation of the growing polymer chain. Under optimized conditions, Krel increases from 15 at 3% monomer conversion to ∼ 138 at 33% conversion, and then reaches a plateau. The steric bulk of both the pendant groups of monomers and the chiral amine ligand critically regulates the magnitude and evolution of DNLEs, and reducing this bulk leads to a pronounced decrease in Krel. Chain extension experiments using the preformed helical macroinitiators exhibited a constant Krel, confirming that a well-formed helical conformation maintains stable enantioselectivity for AKRP. Computational studies further revealed that, during chain propagation, decameric species with well-developed helical conformations exhibit more pronounced energy differences between the R- and S-enantiomers than the corresponding initial monomer-inserted species. These results suggest that the one-handed helical conformation is associated with the enhanced enantiomer recognition at the catalytic center. This study reveals DNLEs in AKRP in which enantioselectivity evolves nonlinearly during polymer chain propagation, highlighting a dynamic chiral amplification mechanism that can surpass the intrinsic selectivity of a static catalyst through the cooperative action of chiral chain ends and helical conformation.

Rh-mediated diazoacetate polymerization has garnered significant attention as an effective approach to obtain highly syndiotactic, completely functionalized carbon chain polymers. However, improving catalytic efficiency of the Rh complex by using readily available reagents remains challenging. Herein, we report an unprecedented catalytic system consisting of RhI(cod)Cl]2 (cod = 1,5-cyclooctadiene) and organoamine that can polymerize various diazoacetates to afford well-defined syndiotactic polycarbenes in high yields, with large molar masses and narrow dispersities. A combination of thorough mechanistic characterization and DFT calculations reveals that the chain propagation may start with [(cod)RhI-H(NEt3)] species, formed by the oxidative addition of [(cod)RhI-Cl(NEt3)] with trace ethanol in reaction solvent and subsequent reductive β-H elimination. Optically active helical polymers also form from achiral bulky diazoacetates when enantiomerically pure amines serve as ancillary reagents. Those polymers without traditional luminophore exhibit interesting circularly polarized photoluminescence. The present work demonstrates a promising route to explore high-performance Rh-based catalysts for carbene polymerization and develop advanced functional materials.

Anion exchange membrane water electrolyzers present a promising approach to cost-effective green H₂ generation, whereas integration of alkaline media and dry-cathode conditions intrinsically forbids adequate H₂O/OH^- conduction for efficient operation at high current densities. Herein, we develop a quinuclidinium-functionalized membrane possessing a modulated nano-porous architecture, and exploit its synergy with regulated configuration featuring an anode-to-cathode pressure gradient. By facilitating H₂O permeation across interconnected hydrophilic nano-channels, a performance of 11.2 A·cm^-2 at 2 V and 90 °C is realized using a NiFe anode, while sufficient membrane robustness and durability enable 2000 h operation at 1 A·cm^-2 with suppressed decay of -1. The narrowed (1-2 nm) gas avenues coordinate with applied pressure gradient to mitigate H₂ crossover, improving adaptability to various static-dynamic scenarios. An encouraging levelized cost of H₂ of 1.8 $·kg^-1 unveils the promise for up-scaled deployment, and this proposed membrane-condition collaboration advances to innovate next-generation energy technologies.

Achieving dynamic motions in molecular crystals with both long-range displacement and precise control remains a central challenge. Herein, we report a light-driven rolling motion in twisted single crystals of 9-cyanoanthracene, representing a new motility paradigm that combines structural asymmetry with directional actuation. Under UV irradiation, straight crystals exhibit limited bending due to anisotropic lattice expansion from localized [4 + 4] photodimerization. However, when twisted into helices, they roll rapidly and directionally toward the light source. Systematic investigations reveal that rolling is driven by a transient, light-induced shift in the center of mass, which generates torque through the misalignment of gravitational and normal forces. The rolling velocity can be finely tuned through external parameters including light intensity and incidence angle, as well as internal structural features including crystal length, width, and helical pitch. While the handedness of helicity does not affect rolling velocity under unconstrained conditions, introducing a lateral constraint with a fine wire reveals a distinct helicity-dependent deflection in the rolling trajectory. Specifically, when rolling toward the light, left-handed helices consistently deviate to the right, whereas right-handed helices deviate to the left. This helicity-biased rolling arises from asymmetric contact forces during rolling and highlights the role of contact mechanics in translating structural chirality into directional motion. This work establishes rolling as a conceptually novel mode of crystal actuation, demonstrating how structural chirality and photoreactivity can be synergistically harnessed to impart directionality to dynamic motion. Our findings lay the foundation for developing advanced smart materials with complex, programmable functionalities based on molecular crystals.

Two-dimensional (2D) chiral materials offer exciting opportunities in sensing and catalysis, yet achieving mesoscale chirality in 2D organic assemblies remains challenging. We introduce a bioinspired strategy to fabricate 2D vortex-like platelets with mesoscale chirality from DNA-mimicking helically grooved poly(phenylacetylene) derivatives via interchain twisted coupling. By tuning assembly kinetics including solvent exchange rate and temperature, we program both the handedness and curvature of mesoscopic chirality. Theoretical simulations show that inherent chain helicity dictates twist direction, while assembly conditions govern angular magnitude. Polymers with helical grooves outperform rigid rod-like analogues: their fluted surfaces serve as stereochemical "hotspots", channeling torsional stress to enable directional coupling across the plane. Dependence of mesoscale chirality on polymer molecular weights further confirms the universality of helical-groove-driven chiral amplification. These vortex platelets exhibit enhanced circularly polarized luminescence (CPL) superior to regular achiral 2D ones. This work offers new insights into both mechanistic understanding of hierarchical chirality transfer and an engineering framework for biomimetic mesoscale chiral materials.

Natural polymers have been used as stereoselective crystallization inhibitors benefiting from their intrinsic hierarchical chirality. However, the chirality of their constituent unit is intrinsically immutable due to the natural biosynthetic origin of biopolymers, fundamentally limiting their versatility, as they cannot be synthetically inverted to target the opposite enantiomer. Herein, we designed a magnetic nanosplitter by grafting cellulose acetate phthalate onto Fe₃O₄ nanoparticles to selectively interact with the crystals of one enantiomer, enabling them to form magnetized crystals that can be efficiently separated from their racemic conglomerate with an external magnetic field. This approach enabled the resolution of racemic nimodipine, simultaneously yielding considerable quantities of magnetic S-crystals and nonmagnetic R-crystals. It should be mentioned that using pristine natural polymer derivatives can only obtain crystals of one enantiomer, the less pharmacologically active R-crystals. Further structural investigation revealed that the chain length of the polymer and the size of Fe₃O₄ nanoparticles significantly influence the resolution of the nanosplitters. When containing cellulose acetate phthalate with a molecular weight above 20 kDa and Fe₃O₄ cores sized between 5 and 14 nm, the optimal performance has been achieved, producing S- and R-enantiomers with 82 ee% and 92 ee%, respectively, and a combined yield of 40%. This work pioneers a magnetically driven separation strategy that can be seamlessly integrated into automated chiral separation platforms.

Two-dimensional (2D) materials with a unique planar geometry have garnered significant attention. The high-energy edges of 2D materials, distinct in structure and properties from large surfaces, enable post-modification for novel hybrid materials but remain rarely explored. Here, this work proposes a co-assembly strategy to fabricate chiral hybrid materials by templating gold nanorods (GNRs) along the edge of 2D poly(phenylacetylene) (PPA) nanosheets, enabling their arrangement into chiral assemblies. This approach achieves rapid chiral packing of GNRs, yielding strong plasmonic circular dichroism (PCD) signals with the maximum dissymmetric factor g_abs ∼ ±0.05 within one minute. Unlike large surfaces, the edges of nanosheets induce GNRs to align at specific tilted angles by the helicity of PPA side chains, as confirmed by simulated circular dichroism (CD) and extinction spectra of the chiral GNR assemblies. Furthermore, the resulting chiral hybrid nanostructures significantly enhance the circularly polarized luminescence (CPL) of PPA nanosheets, establishing their potential as chirality filters. The strong coupling between the GNRs and PPA side groups is attributed to multiple non-covalent interactions, as demonstrated by Raman, electronic circular dichroism (ECD), and vibrational circular dichroism (VCD) spectroscopies. This study underscores the synergistic communication between polymeric 2D assemblies and inorganic nanoparticles in the development of advanced chiral materials.