Chuanjie Fang

Covalent organic frameworks (COFs) provide a structurally programmable platform for membrane‐based separation of small‐molecule active pharmaceutical ingredients (APIs). Nevertheless, constructing membrane pores with subnanometer precision and resolving structurally similar molecular mixtures remain major challenges. Herein, we report an isoreticular contraction strategy to construct a series of kgd‐topology COF membranes with progressively narrowed apertures in situ on polyacrylonitrile (PAN) substrates through contra‐diffusion interfacial polymerization between hexa(4‐formylphenyl)benzene (HFPB) and three triamine monomers of decreasing size. Systematic framework contraction decreased the aperture from 12.1 to 10.2 Å and then to 6.5 Å, giving molecular weight cut‐offs of 500, 380, and 290 Da, respectively. Notably, membranes with different contraction degrees were further integrated into a cascade separation system with well‐separated molecular‐weight rejection thresholds, enabling the purification of a four‐component mixture of camptothecin‐related compounds with equal mass concentrations, achieving a maximum fraction purity of 96.6%. This work establishes isoreticular contraction as an effective strategy for programming transport‐relevant pores in COF membranes and highlights the potential of kgd‐topology COF membranes for cascade pharmaceutical purification.

Positively charged polyamide (PA) nanofiltration (NF) membranes hold great potential for Mg2+/Li+ separation, but their performance is strongly affected by the surface properties and pore structures of the substrate. In this study, a PES ultrafiltration substrate was pretreated by ethanol natural evaporation and then activated by oxygen plasma prior to interfacial polymerization to fabricate composite NF membranes. The pretreatment effectively suppressed irreversible pore shrinkage of the PES substrate during drying, enabling the E-PES-UF substrate to maintain a high water flux of 228 LMH. Subsequent oxygen plasma activation improved the hydrophilicity and interfacial wettability of the substrate through mild etching and the introduction of polar oxygen-containing groups, thereby promoting the uniform distribution of PEI aqueous-phase monomers on the activated substrate surface. As a result, the optimized E-30-20-NF membrane exhibited a uniform PA layer with a thickness of only 37 nm and an isoelectric point of pH 8.85. It achieved a Mg2+ rejection of 99.3%, a separation factor of 52.8, and a permeation flux of 21.1 LMH. During the 120 h continuous-filtration test, the Mg2+ rejection remained above 98.9%, while the Mg2+/Li+ mass ratio in the permeate was maintained at 0.28–0.40. The membrane also exhibited a good antifouling performance.

Developing precise and speedy molecular recognition technologies is critical for urban smart agriculture and medicine. Terahertz (THz) spectroscopy has been widely applied in molecular detection owing to its unique non-destructive and label-free nature. However, current THz sensing devices often suffer from complex fabrication processes structures and low detection performance. 2D Metal organic frameworks (MOFs) have garnered significant interest due to their high adsorption capacity and abundant molecular attachment sites. In this work, we employed 2D MOF as lossy layer and deposited it onto dielectric layer of planar sensor. High specific areas (413 m²/g) and precise nanopores (3.86 nm) of 2D MOF enabled abundant interaction between 2D MOF and pesticide, yielded a binding energy of -6.26 kcal/mol by density functional theory (DFT) analysis. This sensor presents exceptional performance for imidacloprid detection, achieving a low limit of detection (LOD) of 0.076 μg/L. Its practical utility was further validated through pesticide detection at green vegetable surfaces, presenting the potential for on-site detection applications.

Membrane technology holds significant promise in the antibiotics desalination. However, its practical application is constrained by the limited controllability over membrane microstructures, including pore architecture and surface charge distribution. This study proposed a two-dimensional (2D) confined interfacial polymerization (IP) strategy to address the manipulability of the nanochannel morphology and the charge distribution for fabricating membrane with high performance of antibiotic desalination. The polyethyleneimine(PEI)-grafted amino-functionalized GO nanosheets were used as building blocks to construct ultra-thin 2D nanochannel membranes, further introduction of trimesoyl chloride (TMC) triggered the interface polymerization (IP) reaction within the confined space, which not only repairs the defects but also precisely regulates the charge distribution within the nanochannels. The optimized ultra-thin (only 48.6 nm thick) membrane existed more orderly interlayer channels and a nearly neutral charge distribution. These structural advantages yielded an unexpected antibiotics desalination performance with a water permeance of 176.2 L m-2 h-1 bar-1 and NaCl/tetracycline (TC) selectivity of 75.7 under the synergy of the enhanced size sieving and the eliminated electrostatic exclusion effect. Furthermore, this membrane demonstrated outstanding long-term stability. This study provides a scientific reference for developing high-performance membrane towards pharmaceutical industry and water purification.

Novel polymers of intrinsic microporosity (PIMs) exhibit rigidity and non‐planar structures, which make them promising for constructing high‐permeability separation materials. However, the intrinsic hydrophobicity of PIMs limits their application in separation membranes for aqueous systems. Herein, we report an in situ interfacial polymerization strategy utilizing a catechol‐functionalized PIM monomer in conjunction with dopamine (DA) to fabricate a thin‐film composite (TFC) nanofiltration membrane with intrinsic microporosity. In this process, the aqueous‐phase monomer, 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′spirobiindan (TTSBI), modulated the pore size distribution, which facilitated water transport and enhanced permeance, while DA improved hydrophilicity and adhesion. Furthermore, the steric hindrance imparted by the contorted structure of TTSBI interfered with the self‐polymerization and assembly behavior of DA, inhibiting the formation of larger aggregates and consequently reducing structural defects within the composite layer. The resulting composite membrane exhibits a narrow pore size distribution (0.3–0.4 nm), high Vitamin B ₁₂ (VB ₁₂ ) rejection rate (92.5%), and outstanding permeance (4.6 L m ⁻² h ⁻¹ bar ⁻¹ ). Moreover, long‐term testing demonstrated excellent stability, with only a 4.4% decline in rejection after 96 h. This work provides valuable insights for the fabrication of high‐performance nanofiltration membranes for water treatment.

Covalent organic frameworks (COFs) with customizable pore structures have aroused immense interest in pharmaceutical separation relying on organic solvent nanofiltration (OSN). Nevertheless, devising durable COF membranes with fine nanochannels for high‐efficiency separation remains challenging. Here, a triangular‐topology COF membrane is reported with subnanometer pores through designing a six‐fold symmetric hexa(4‐formylphenyl)benzene as a building block. A dense COF membrane is interfacially synthesized through the sustained diffusion and reaction of hydrazine from porous substrates under catalysis. Thus‐synthesized membrane features an ultrathin thickness of 54 nm, high‐density nanochannels, and high solvent affinity. The membrane yielded exceptional solvent permeances (24.9 L m ⁻¹ h ⁻¹ bar ⁻¹ for methanol) and sharp molecular rejection curves with low molecular weight cut‐offs of 380 Da, outperforming congeneric OSN membranes. This further translated into an excellent separation capability toward mixed antitumor pharmaceuticals within organic solvents, despite under high concentration and prolonged operation. This skillful design drives COF membranes as a promising candidate for reforming separation processes of high‐value pharmaceuticals in industries.

Microporous polymer membranes with high solvent permeability are pivotal for upgrading molecular separations in organic solvents, but this remains challenging due to numerous sub‐0.4 nm ultra‐micropores resulting from local tight packing, which limit solvent‐accessibility. Herein, a microporous polyimide with high intrinsic free volume [PI‐TB‐NDI, naphthalenediimide (NDI) and Tröger's base (TB)] is synthesized for organic solvent nanofiltration. The resulting polymer showed high free volume because of fused aromatic rings and a twisted structure. Aromatic rings enhanced solvent resistance due to strong molecular interaction, but increased detrimental local tight packing as well. To suppress local tight packing without compromising the molecular interactions vital for stability, an ortho ‐methyl group is deliberately introduced onto the TB unit to increase both intra‐ and inter‐molecular steric hindrance, imparting an H‐shaped TB‐NDI‐TB molecular stent. On the introduction of ortho ‐methyl groups, the sub‐0.4 nm ultra‐micropores are enlarged to ultra‐micropores (0.6–0.7 nm) to give the membrane with rich solvent‐accessible sub‐nanochannels. This resulted in an unprecedented enhancement of solvent permeability, with ethanol permeability 2‐8 times greater than that of state‐of‐the‐art polymer membranes with similar selectivity. These findings advance the design strategy of microporous membranes with well‐tailored free volume without post‐treatments, enabling upscaling and efficient separation of precious species in organic solvents.