Embedding Functional Biomacromolecules within Peptide-Directed Metal–Organic Framework (MOF) Nanoarchitectures Enables Activity Enhancement

Rationally tailoring a robust artificial coating can enhance the life-time of fragile biomacromolecules. However, the coating also can restrain the activity of the guest because of the decreased substrate accessibility. Herein, we report a peptide-directed strategy that enables in situ tailoring of the MOF-shrouded biohybrids into controllable nanoarchitectures. The MOF biohybrid can be shaped from different 3D microporous architectures into a 2D mesoporous layer by a peptide modulator. Using this mild strategy, we show that the nanoarchitectures of the MOF coatings significantly affect the biological functions of the contained biomacromolecules. The biomacromolecules entrapped within the novel 2D mesoporous spindle-shaped MOFs (2D MSMOFs) have significantly increased bioactivity compared to when encased within the hitherto explored 3D microporous MOFs. The improvement results from the shortened diffusion path and enlarged pore channel in 2D MSMOFs. Meanwhile, the thin 2D MSMOF layer also can provide excellent protection of the hosted biomacromolecules or protein-scaffolded biominerals through structural confinement.     

An Electrochromic Hydrogen-Bonded Organic Framework Film

Hydrogen-bonded organic frameworks (HOFs) possess various merits, such as high porosity, tunable structure, facile modification, and ready regeneration. These properties have yet to be explored in the context of new functional HOF materials. The facile and inexpensive electrophoretic deposition (EPD) method applied in this study generated a transparent HOF film at room temperature in just 2 min and is applicable to other HOFs. The resulting film exhibited reversible electrochromism with the advantage of long cycle life (>500 cycles). More strikingly, this all-organic film could be readily regenerated (through rinsing with DMF and redeposition) and showed tunable electrochromic behavior (through low-cost postsynthetic modification) with the ability to undergo successive color changes, which is difficult to achieve with conventional electrochromic materials. An electrochromic device was manufactured to further demonstrate the application potential of the film.     

Irreversible Amide-Linked Covalent Organic Framework for Selective and Ultrafast Gold Recovery

Design of stable adsorbents for selective gold recovery with large capacity and fast adsorption kinetics is of great challenge, but significant for the economy and the environment. Herein, we show the design and preparation of an irreversible amide-linked covalent organic framework (COF) JNU-1 via a building block exchange strategy for efficient recovery of gold. JNU-1 was synthesized through the exchange of 4,4′-biphenyldicarboxaldehyde (BA) in mother COF TzBA consisting of 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)trianiline (Tz) and BA with terephthaloyl chloride. The irreversible amide linked JNU-1 gave good stability, unprecedented fast kinetics, excellent selectivity and outstanding adsorption capacity for gold recovery. X-ray photoelectron spectroscopy along with thermodynamic study and quantum mechanics calculation reveals that the excellent performance of JNU-1 for gold recovery results from the formation of hydrogen bonds C(N)−H⋅⋅⋅Cl and coordinate interaction of O and Au. The rational design of irreversible bonds as both inherent linkage and functional groups in COFs is a promising way to prepare stable COFs for diverse applications.     

MOF-Mediated Fabrication of a Porous 3D Superstructure of Carbon Nanosheets Decorated with Ultrafine Cobalt Phosphide Nanoparticles for Efficient Electrocatalysis and Zinc–Air Batteries

Superstructures have attracted great interest owing to their potential applications. Herein, we report the first scalable preparation of a porous nickel-foam-templated superstructure of carbon nanosheets decorated with ultrafine cobalt phosphide nanoparticles. Uniform two-dimensional (2D) Co-metal organic framework (MOF) nanosheets (Co-MNS) grow on nickel foam, followed by a MOF-mediated tandem (carbonization/phosphidation) pyrolysis. The resulting superstructure has a porous 3D interconnected network with well-arranged 2D carbon nanosheets on it, in which ultrafine cobalt phosphide nanoparticles are tightly immobilized. A single piece of this superstructure can be directly used as a self-supported electrode for electrocatalysis without any binders. This “one-piece” porous superstructure with excellent mass transport and electron transport properties, and catalytically active cobalt phosphide nanoparticles with ultrasmall size (3–4 nm), shows excellent trifunctional electrocatalytic activities for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR), achieving great performances in water splitting and Zn–air batteries.     

Highly Conducting Organic–Inorganic Hybrid Copper Sulfides CuxC6S6 (x=4 or 5.5): Ligand-Based Oxidation-Induced Chemical and Electronic Structure Modulation

Conductive coordination polymers (CPs) have potential in a wide range of applications because of their inherent structural and functional diversity. Three electrically conductive CPs (Cu_xC₆S₆, x=3, 4 or 5.5) derived from the same organic linker (benzenehexathiol) and metal node (copper(I)) were synthesized and studied. Cu_xC₆S₆ materials are organic–inorganic hybrid copper sulfides comprising a π-π stacking structure and cooper sulfur networks. Charge-transport pathways within the network facilitate conductivity and offer control of the Fermi level through modulation of the oxidation level of the non-innocent redox-active ligand. Two Cu_xC₆S₆ (x=4 or 5.5) CPs display high electrical conductivity and they feature a tunable structural topology and electronic structure. Cu₄C₆S₆ and Cu_5.5C₆S₆ act as degenerate semiconductors. Moreover, Cu_5.5C₆S₆ is a p-type thermoelectric material with a ZT value of 0.12 at 390 K, which is a record-breaking performance for p-type CPs.     

一种二维吖嗪共价有机骨架材料涂层毛细管的制备及其用于开管-毛细管电色谱分离硝基苯酚类环境内分泌干扰物

作为一种新型多孔晶体材料,共价有机骨架材料（COFs）由于具有比表面积大、密度小、稳定性高及孔径可调等特点而在诸多领域中得到了广泛的应用。但将其用作固定相以提高开管-毛细管电色谱（OT-CEC）分离效率的研究报道较少。鉴于此,该文参考文献方法合成了一种二维吖嗪COF（ACOF-1）,然后以ACOF-1作为固定相制备了ACOF-1涂层毛细管并以其为分离通道建立了一种分离硝基苯酚类环境内分泌干扰物（EEDs）的OT-CEC新方法。通过X射线粉末衍射、傅里叶变换红外光谱和扫描电子显微镜等表征手段证明成功合成并制备了ACOF-1和ACOF-1涂层毛细管。实验结果表明,在最佳分离条件下,所建立的OT-CEC方法可在20 min内实现2-硝基苯酚、4-硝基苯酚、2,4-二硝基苯酚和2,4,6-三硝基苯酚4种硝基苯酚分析物的基线分离。4种分析物的线性范围分别为10~500 mg/L和20~1000 mg/L,决定系数均大于0.99,检出限和定量限分别为0.13~0.23 mg/L和0.45~0.60 mg/L。迁移时间和峰面积的日内、日间及柱间相对标准偏差均不超过9.4%,表明所建立的方法重现性好,稳定性高,可用于硝基苯酚类EEDs的分离检测。分离机理研究表明ACOF-1孔结构对各分析物的尺寸选择作用是影响分离行为的主要因素。该工作证明了以COFs作为固定相的OT-CEC方法用于分离检测EEDs的可行性,后续将继续围绕COFs涂层毛细管的制备及其用于OT-CEC分离测定EEDs开展研究。     

以氧化锌为锌源的手性金属-有机骨架的合成及其用于联糠醛外消旋体的选择性吸附

通过使用氧化锌代替传统的金属无机盐为锌源,制备了手性金属-有机骨架（CMOF）[Zn（L-mal）（H₂O）₂]_n并对其手性分离性能进行了考察。将ZnO和L-苹果酸按物质的量之比1：1溶于水中,在室温下静置24 h即可得到[Zn（L-mal）（H₂O）₂]_n。以100 mg[Zn（L-mal）（H₂O）₂]_n为吸附剂,将250 μL 1 g/L的联糠醛外消旋体加入其中,并以4.5 mL异丙醇和1 mL甲醇为萃取剂和洗脱剂进行选择性吸附实验,最终滤液使用高效液相色谱仪（HPLC）进行分析。结果表明,[Zn（L-mal）（H₂O）₂]_n对R-联糠醛具有较好的选择性吸附,其对映体过量（ee）值为20%。该工作为CMOF的绿色制备提供了一定的方法和经验并拓展了其在手性分离领域的应用。     

ZIF-76-mbIm膜的制备及其CO2分离研究

采用二次生长法在α-Al₂O₃载体上制备ZIF-76-mbIm膜, 从纳米晶种的制备、晶种层厚度的优化以及二次生长条件优化3个方面进行调控以制备连续致密的ZIF-76-mbIm膜, 并使用聚二甲基硅氧烷(PDMS)对ZIF-76-mbIm膜进行修饰, 提高膜的机械强度. 使用X射线衍射、扫描电子显微镜对膜的形貌结构进行表征, 通过Wicke-Kallenbach方法测试所得ZIF-76-mbIm膜对CO₂/N₂二元混合物的分离性能. 结果表明: 经PDMS修饰的ZIF-76-mbIm膜对CO₂/N₂的分离系数可达15.53, 对应CO2的渗透率为7.98×10-9mol?(m2?s?Pa)-1.     

二氧化碳在柔性ZIF-8笼中平均停留时间的分子动力学模拟

采用巨正则蒙特卡洛和分子动力学模拟方法研究了二氧化碳分子在柔性ZIF-8材料中吸附位点和扩散机理. 通过构建合理的时间相关函数,得出了二氧化碳分子在柔性ZIF-8笼中的平均停留时间. 结果表明,二氧化碳分子待在同一个笼中的停留时间可达到几十个皮秒. 并且发现平均停留时间几乎随着压力(或负载量)的增加而线性增加.     

Evaluation of copper-1,3,5-benzenetricarboxylate metal-organic framework (Cu-MOF) as a selective sorbent for Lewis-base analytes

The metal-organic framework copper-1,3,5-benzenetricarboxylate (Cu-BTC) was evaluated for its ability to selectively interact with Lewis-base analytes by examining retention on gas-chromatographic columns packed with Chromosorb W HP that contained 3.0% SE-30 along with various loadings of Cu-BTC. Scanning electron microscopy images of the support material showed the characteristic Cu-BTC crystals embedded in the SE-30 coating on the diatomaceous support. The results indicated that the Cu-BTC-containing stationary phase had limited thermal stability (220 °C) and strong general retention for analytes. Kováts index calculations showed selective retention (amounting to about 300 Kováts units) relative to n-alkanes for many small Lewis-base analytes on a column that contained 0.75% Cu-BTC compared with an SE-30 control. Short columns that contained lower loadings of Cu-BTC (0.10%) allowed elution of nitroaromatics; however, selectivity was not observed for aromatic compounds (including nitroaromatics) or nitroalkanes. Observed retention characteristics are discussed.