The crystallization problem is an outstanding challenge in the chemistry of porous covalent organic frameworks (COFs). Their structural characterization has been limited to modeling and solutions based on powder x-ray or electron diffraction data. Single crystals of COFs amenable to x-ray diffraction characterization have not been reported. Here, we developed a general procedure to grow large single crystals of three-dimensional imine-based COFs (COF-300, hydrated form of COF-300, COF-303, LZU-79, and LZU-111). The high quality of the crystals allowed collection of single-crystal x-ray diffraction data of up to 0.83-angstrom resolution, leading to unambiguous solution and precise anisotropic refinement. Characteristics such as degree of interpenetration, arrangement of water guests, the reversed imine connectivity, linker disorder, and uncommon topology were deciphered with atomic precision-aspects impossible to determine without single crystals.

b S Supporting InformationT he porous materials with extraordinarily high surface area have attracted enormous scientific attention due to their diverse potential applications in separation, 1 heterogeneous catalysis, 2 and gas storage. 3 During the last few decades, the surge to develop such useful materials has led scientists to produce a number of novel porous materials such as metal organic frameworks (MOFs), 4 covalent organic frameworks (COFs), 5 porous organic cages, 6 and microporous organic polymers (MOPs), 7 in addition to traditional porous materials such as zeolites and activated carbon etc. Among these porous materials, MOPs have attracted a particular attention due to their unique properties such as large surface area, low skeletal density and high chemical stability. "Davankov resins", that is, styrenetype polymers hypercrosslinked by FriedelÀCrafts reaction, 8 are one of the earliest types of MOPs and have been studied extensively, coming into industrial practice at the end of 1990s, however, the releasing hydrogen halide as byproduct is detrimental and hard to tackle. 3d,9 Hyper-cross-linked polypyrrole or polyaminobenzene or aminobenzene represent another kind of pioneering MOPs. 10 These two synthesis method can only be adapted to very limited monomers. Very recently, various other new kinds of MOPs have been developed, based on several types of reaction, such as polymers of intrinsic microporosity (PIMs) with dioxane unit, 3b microporous polymers such as conjugated microporous polymers (CMPs) 11 and porous aromatic frameworks (PAFs) 12 by various cross-coupling reactions of aromatic compound. MOPs were also formed by trimerizations of ethynyl 13 or nitrile groups, 14 by amide or imide or imine formation, 15 and via "click" chemistry. 16 All of these approaches have aimed to develop new microporous organic materials with higher surface areas and controlled pore sizes and functions. However, the transition metal catalysts or noble metal catalysts used for synthesis of CMPs, PAFs, and some other MOPs are expensive and rare. It is often also complicated to synthesize the monomers which must bear halogen, 11a ethynyl 17 or stereocontrolled structures such as spirocyclic monomers 17,18 used in MOPs. Hence, the sustainable mass production of MOPs is an unanswered challenge.In this report, we propose a new strategy, which involves "knitting" rigid building blocks with an external cross-linker. We used a simple one-step FriedelÀCrafts reaction of a low-cost cross-linker with ordinary, low functionality aromatic compounds to produce cost-effective microporous polymers with very high surface areas and the only byproduct was methanol. In this one-step cross-linking approach, formaldehyde dimethyl acetal (FDA) was used as an external cross-linker to react with various aromatic monomers (Scheme 1, parts aÀc). Typically, the monomer (e.g., benzene, 0.02 mol, 1.56 g), cross-linker (FDA, 0.06 mol, 4.56 g) and the catalyst (FeCl 3 , 0.06 mol, 9.75 g) were dissolved in 1,2-dichloroethane (DCE, 20 mL) and heate...

We report herein the first example of interpenetration isomerism in covalent organic frameworks (COFs). As a well-known three-dimensional (3D) COF, COF-300 was synthesized and characterized by the Yaghi group in 2009 as a 5-fold interpenetrated diamond structure ( dia-c5 topology). We found that adding an aging process prior to the reported synthetic procedure afforded the formation of an interpenetration isomer, dia-c7 COF-300. The 7-fold interpenetrated diamond structure of this new isomer was identified by powder X-ray diffraction and rotation electron diffraction analyses. Furthermore, we proposed a universal formula to accurately determine the number of interpenetration degrees of dia-based COFs from only the unit cell parameters and the length of the organic linker. This work not only provides a novel example to the category of interpenetration isomerism but also provides new insights for the further development of 3D COFs.

The synthesis of a block codendrimer (g3-PBE-b-g3-PMDC), composed of a third-generation poly(benzyl ether) (PBE) monodendron and an aliphatic polyether (PMDC) monodendron is reported. In THF/diiospropyl ether (1:1) the PMDC block functions as a "hydrophilic" block, while the PBE acts as a "hydrophobic" block. The codendrimer can form interdigitated layers leading to vesicle formation. Tapping mode atomic force microscopy (AFM), dynamic light scattering (DLS), and transmission electron microscopy (TEM) were used to characterize the vesicles. The effect of molecular architecture on the formation of the interdigitated layers and vesicles was studied.

An organic-inorganic hybrid polymer composed of a Dawson trivanadium-substituted heteropolytungstate ((Bu 4 N) 5 [H 4 P 2 W 15 V 3 O 62 ]) cluster and PS chain are originally designed and first synthesized via in situ ATRP. Further characterization includes NMR spectroscopy, FT-IR spectroscopy, and GPC which proved the purity of the material. By means of a cation exchange process, a hybrid polymer (Bu 4 N) þ -POM-PS was tuned into a novel giant amphiphile H þ -POM-PS. Immediately, individual molecules self-assembled into kinetically favored hybrid vesicles in DMF. Our work provides a controllable and rational way to fabricate stable and well-defined POM-polymer hybrid polymers that can be optimized for potential applications.

Structural engineering and compositional controlling are extensively applied in rationally designing and fabricating advanced freestanding electrocatalysts. The key relationship between the spatial distribution of components and enhanced electrocatalysis performance still needs further elaborate elucidation. Here, CeO2 substrate supported CoS1.97 (CeO2‐CoS1.97) and CoS1.97 with CeO2 surface decorated (CoS1.97‐CeO2) materials are constructed to comprehensively investigate the origin of spatial architectures for the oxygen evolution reaction (OER). CeO2‐CoS1.97 exhibits a low overpotential of 264 mV at 10 mA cm−2 due to the stable heterostructure and faster mass transfer. Meanwhile, CoS1.97‐CeO2 has a smaller Tafel slope of 49 mV dec−1 through enhanced adsorption of OH−, fast electron transfer, and in situ formation of Co(IV)O2 species under the OER condition. Furthermore, operando spectroscopic characterizations combined with theoretical calculations demonstrate that spatial architectures play a distinguished role in modulating the electronic structure and promoting the reconstruction from sulfide to oxyhydroxide toward higher chemical valence. The findings highlight spatial architectures and surface reconstruction in designing advanced electrocatalytic materials.

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By using 13C solid-state NMR, monitoring the reactivity of methoxy species with carbon monoxide has been performed on 12-tungstophosphoric acid, H3PW12O40, at 423−473 K. Surface methoxy species have been selectively prepared from methanol at 293−423 K. Almost quantitative conversion of surface methoxy species into acetyl groups bound to the Keggin anion and acetic acid has been observed at 473 K. These data provide unambiguous evidence for the role of methoxy species as the intermediate of methanol and dimethyl ether carbonylation on solid H3PW12O40. The formation of a trimethyloxonium ion has been detected on the surface of heteropolyacid for the first time. The carbonylation of trimethyloxonium proceeds via the analogous mechanism through the methoxy species intermediate.