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Two 2-dimensional covalent organic frameworks (COFs; TJNU-203 and TJNU-204) with high crystallinity and large specific surface area are rationally fabricated using a three-connected distorted building block and linear linkers. The two COFs show high iodine uptake (5.885 g g−1 for TJNU-203 and 5.335 g g−1 for TJNU-204) on account of physical–chemical adsorption, which make them one among the best porous materials for iodine adsorption. [ABSTRACT FROM AUTHOR]

Summary of main observation and conclusion: A highly efficient catalytic system for the N‐arylation reactions of (hetero)aryl chlorides and nitrogen heterocycles with a copper(I) complex containing a 1,10‐phenanthroline analogue N‐heterocyclic carbene (NHC) has been reported. The complex was characterized by 1H NMR and 13C NMR spectroscopy and elemental analysis, and its structure was determined by single‐crystal X‐ray diffraction. The NHC‐copper(I) complex was employed as pre‐catalyst for Ullmann type N‐arylation reactions of (hetero)aryl chlorides with various azoles. A variety of hindered and functionalized azoles and (hetero)aryl chlorides were transformed in good to excellent yields. [ABSTRACT FROM AUTHOR]

Radioactive iodine in nuclear waste is increasingly harmful to nature with the continuous development and utilization of nuclear energy. Herein, two new two-dimensional covalent–organic frameworks (COFs, TJNU-201 and TJNU-202) were designed and synthesized by using sterically hindered 1,3,5-trimethyl-2,4,6-tris(4-aminophenyl)-benzene as a three-connected building block. Both COFs showed ultrahigh iodine capture capacity (5.625 g g−1 for TJNU-201 and 4.820 g g−1 for TJNU-202), which can be attributed to the physical–chemical adsorption. [ABSTRACT FROM AUTHOR]

Covalent‐organic frameworks (COFs) as porous crystalline materials show promising potential applications. However, developing facile strategies for the construction of COFs directly from amorphous covalent organic polymers (COPs) is still a great challenge. To this end, we report a novel approach for easy preparation of COFs from amorphous COPs through the linkage replacement under different types of reactions. Four COFs with high crystallinity and porosity were constructed via the linkage substitution of polyimide‐linked COPs to imine‐linked COFs as well as imine‐linked COPs to polyimide‐linked COFs. The realization of the linkage substitution would significantly expand the research scope of COFs. [ABSTRACT FROM AUTHOR]

Supramolecular self‐assembly stands for the spontaneous aggregation of small organic compounds or polymers into ordered structures at any scale. When being induced by inherent molecular chiral centers or ambient asymmetric factors, asymmetric spatial arrangement between building units shall occur, which is defined as supramolecular chirality. Except for molecular design, utilizing external stimulus factors to tune supramolecular chirality is a promising approach. In this Concept article, we particularly discuss the important role of solvents in manipulating the chirality of self‐assembled systems. The impact of solvents on the chirality is generally based on three properties of solvents, i.e. chirality, polarity, and active coassembly with building blocks. Molecular self‐assembly in chiral solvents could undergo the chirality transfer, exhibiting a chiral induction effect. Solvent polarity often determines intermolecular orientation. As a consequence, those building blocks with both polar and apolar segments might change their chirality depending on the solvent polarity. We elaborate the active participation of solvent molecules into ordered structures together with building blocks, where solvents and building blocks exhibit a coassembly manner. By specific treatments such as heating and cooling, solvents could be released or re‐entrapped, allowing a smart control over supramolecular chirality. The solvent effect in manipulating two‐dimensional chiral self‐assemblies is then discussed. The perspective and future development in this research field are presented at last. [ABSTRACT FROM AUTHOR]

The field of covalent organic frameworks (COFs) has been developed significantly in the past decade on account of their important characteristics and vast application potential. On the other hand, the discovery of novel synthetic methodology is still a challenging task to further promote the preparation of COFs. Herein, an interesting protocol for the conversion of amorphous nonporous covalent organic polymers (COPs) to COFs was established, affording four COFs with high crystallinity and porosity. Specifically, imine‐linked amorphous COP‐1 was successfully converted to COF‐1–4 by replacing one type of linker with other organic building blocks. The realization of this conversion provides a facile method for constructing COFs from COPs. Transformation: A novel strategy was developed to construct highly crystalline and porous covalent organic frameworks from amorphous covalent organic polymers by simply replacing the linker with other organic building blocks. This approach shows advantages for a facile preparation of covalent organic frameworks. [ABSTRACT FROM AUTHOR]

Three Co‐based isostructural MOF‐74‐III materials with expanded pores are synthesized, with varied extent of fused benzene rings onto sidechain of same‐length ligands to finely tune the pore sizes to 2.6, 2.4, and 2.2 nm. Gas sorption results for these highly mesoporous materials show that alternately arranged fused benzene rings on one side of the ligand could serve as extra anchoring sites for CO2 molecules with π–π interactions, conspicuously enhancing CO2 uptake and CO2/CH4 and CO2/N2 selectivity; while more steric hindrance effect towards open CoII sites were imposed by ligands flanked with fused benzene rings on both sides, compromising such extra‐sites enhancement. In the catalytic conversion of CO2 with propylene oxide to form propylene carbonate, the as‐synthesized MOF‐74‐III(Co) with desired properties of highly exposed and accessible open CoII centers, large mesopore apertures and multi‐interactive sites, demonstrated higher catalytic activity compared with other two MOFs, with benzene rings fused to ligands hampering the functionality of CoII centers as Lewis acid sites. Our results highlight the viability of finely tuning the expanded pores of MOF‐74 isostructure and the effect of fused benzene rings as functional groups onto selective CO2 capture and conversion. Tighten those pores: Three Co‐based isostructural MOF‐74‐III materials with expanded pores are synthesized, with varied amounts of fused benzene rings incorporated into the side chain of same‐length ligands to finely tune the pore sizes to 2.6, 2.4, and 2.2 nm. This series of materials demonstrates high selectivity in CO2/N2 and CO2/CH4 separation, and high activity in CO2 cycloaddition catalysis. [ABSTRACT FROM AUTHOR]

The attractive properties of layered inorganic materials, which make them suitable for numerous applications in chemical industries and life sciences, originated from their crystalline framework structures. Here, we report a new layered germanate PKU-21, which was prepared by the hydrothermal synthesis method using 2-propanolamine (MIPA) as the structure-directing agent. The structure of PKU-21 was determined from synchrotron single-crystal X-ray diffraction and synchrotron powder X-ray diffraction data. It reveals a complicated framework structure containing 18 unique Ge atoms in the asymmetric unit. PKU-21 is the first layered germanate built from both Ge7 and Ge10 clusters, following the 3-dimensional germanate PKU-17. The preparation and structure of PKU-21 are discussed in comparison with PKU-17, which provides new insight into the formation mechanism of germanates. Gas sorption experiments indicate that the layered PKU-21 sample exhibits a better CO2 sorption selectivity over N2 and CH4 at 298 K than at 273 K, making it a promising candidate for CO2 separation. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are periodic two- or three-dimensional polymeric networks with high surface areas, low density, and designed structures. Because COFs are normally prepared based on reversible formation of covalent bonds with relatively weak stability, their structures can be easily broken or damaged due to changes in the surrounding environment. Thus, developing strategies to realize the reconstruction of COFs in order to extend their usage lifetime is crucial for practical applications. In addition, exploring the kinetics of COF growth under varied reaction conditions is important for better understanding the nucleation and growth processes of COFs. In this work, the reformation mechanism of an imine-based COF using an ex situ characterization method was investigated, disclosing an interesting COF reconstruction progress from disorder to order. The present study shows the regeneration ability of COFs, and the developed method could be generalized for broader use in the field. [ABSTRACT FROM AUTHOR]

An imine-based nitrogen-rich covalent-organic framework (COF) was successfully synthesized using two triangular building units under solvothermal reaction condition. The gas adsorption properties of the obtained microporous nitrogen-rich COF were investigated. The results indicated that the activated COF material presented good up take capabilities of CO2 and CH4 at 61.2 and 43.4 cm3·g−1 at 1 atm and 273 K, respectively, showing its application potential in selective gas capture and separation. [ABSTRACT FROM AUTHOR]

Developing gold nanoparticles (AuNPs) with well-designed functionality is highly desirable for boosting the performance and versatility of inorganic-organic hybrid materials. In an attempt to achieve ion recognition with specific signal expressions, we present here 4-piperazinyl-1,8-naphthalimide-functionalized AuNPs for the realization of quantitative recognition of FeIII ions with dual (colorimetric and fluorescent) output. The research takes advantage of 1) quantity-controlled chelation-mode transformation of the piperazinyl moiety on the AuNPs towards FeIII, thereby resulting in an aggregation-dispersion conversion of the AuNPs in solution, and 2) photoinduced electron transfer of a naphthaimide fluorophore on the AuNPs, thus leading to reversible absorption and emission changes. The functional AuNPs are also responsive to pH variations. This strategy for realizing the aggregation-dispersion conversion of AuNPs with returnable signal output might exhibit application potential for advanced nanoscale chemosensors. [ABSTRACT FROM AUTHOR]

This study provides a successful preparation of biocompatible hybrid materials ( 1-GO and 2-GO) by the integration of graphene oxide (GO) with water-soluble pillararenes (bolaamphiphile 1 and tadpolelike amphiphile 2) for dual-mode Raman and fluorescence bioimaging in vitro. The investigations show that pillararenes 1 and 2 were loaded onto the surface of GO through strong hydrogen-bonding interactions. Aqueous suspensions of 1-GO and 2-GO are stable and can be kept for a long time. After confirming their good biocompatibility by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the 1-GO and 2-GO hybrids were endocytosed by HeLa cells for in vitro Raman imaging. It was found that 1-GO presents better Raman imaging than 2-GO. When a fluorescent guest molecule, bipyridinium derivative 3, was added into the suspensions of the hybrids, the suspensions of 1-GO and 2-GO were as stable as the original. The suspensions of the inclusion complexes ( 1-GO⋅ 3 and 2-GO⋅ 3) formed from 1-GO and 2-GO with 3 can also be endocytosed by HeLa cells to enable in vitro fluorescence imaging to be performed. It was found that 1-GO⋅ 3 performs better than 2-GO⋅ 3. The current research has determined the capacities of pillararene-modified GO for combined bioimaging, which paves the way for using these biocompatible materials towards dual-mode diagnostics. [ABSTRACT FROM AUTHOR]

The Cover Feature shows three Co‐based isostructural Metal–Organic Frameworks (MOFs) with expanded pores for the selective capture and catalytic conversion of carbon Dioxide. In their Full Paper, W. Meng et al. finely tune the pore sizes of the MOF‐74‐III(Co) materials by varying the amounts of fused benzene rings incorporated into the side chain of same‐length ligands. This series of materials demonstrates high selectivity in CO2/N2 and CO2/CH4 separation, and high activity in CO2 cycloaddition catalysis. More information can be found in the Full Paper by W. Meng et al. on page 3751 in Issue 21, 2018 (DOI: 10.1002/cssc.201801585). [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are excellent platforms with tailored functionalities in photocatalysis. There are still challenges in increasing the photochemical performance of COFs. Therefore, we designed and prepared a series of COFs for photocatalytic hydrogen generation. Varying different ratios of β-ketoenamine to imine moieties in the linkages could differ the ordered structure, visible light harvesting, and bandgap. Overall, β-ketoenamine-linked COFs exhibited much better photocatalytic activity than those COFs having both β-ketoenamine and imine moieties on account of a nonquenched excited state and more favorable HOMO level in the photoinduced oxidation reaction from the former. Specifically, after in situ growth of β-ketoenamine-linked COFs onto NH 2 -Ti 3 C 2 T x  MXene via covalent connection, the heterohybrid showed an obvious improvement in photocatalytic H 2 evolution because of strong covalent coupling, electrical conductivity, and efficient charge transfer. This integrated linkage evolution and covalent hybridization approach advances the development of COF-based photocatalysts.

Deep understanding and fine tailoring of spontaneous structural evolution of self-assembled arrays are pivotal in the rational design of advanced soft materials. However, an indistinct structure-property relationship and pathway complexity in self-assembly lead to a considerable challenge. Herein, we reveal the self-assembly pathway complexity in spontaneous aggregation of several N -terminated aromatic amino acids. By primarily tuning the incubation time, building blocks appended with alanine and serine selectively form 1:1 hydrated clathrates, enabling the microfiber to transition to crystals. The dynamic water intercalation process was studied by incubation time-dependent morphological changes, powder X-ray diffraction, and single-crystal structure analysis. A pronounced amino acid residue effect on the self-assembly evolution was reflected by supramolecular chirality inversion of the building block having the phenylalanine residue, accomplishing dynamic M - to P -helicity transition within a confined time scale.

Covalent-organic frameworks (COFs) as porous crystalline materials show promising potential applications. However, developing facile strategies for the construction of COFs directly from amorphous covalent organic polymers (COPs) is still a great challenge. To this end, we report a novel approach for easy preparation of COFs from amorphous COPs through the linkage replacement under different types of reactions. Four COFs with high crystallinity and porosity were constructed via the linkage substitution of polyimide-linked COPs to imine-linked COFs as well as imine-linked COPs to polyimide-linked COFs. The realization of the linkage substitution would significantly expand the research scope of COFs., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Supramolecular self-assembly stands for the spontaneous aggregation of small organic compounds or polymers into ordered structures at any scale. When being induced by inherent molecular chiral centers or ambient asymmetric factors, asymmetric spatial arrangement between building units shall occur, which is defined as supramolecular chirality. Except for molecular design, utilizing external stimulus factors to tune supramolecular chirality is a promising approach. In this Concept article, we particularly discuss the important role of solvents in manipulating the chirality of self-assembled systems. The impact of solvents on the chirality is generally based on three properties of solvents, i.e., chirality, polarity, and active coassembly with building blocks. Molecular self-assembly in chiral solvents could undergo the chirality transfer, exhibiting a chiral induction effect. Solvent polarity often determines intermolecular orientation. As a consequence, those building blocks with both polar and apolar segments might change their chirality depending on the solvent polarity. We elaborate the active participation of solvent molecules into ordered structures together with building blocks, where solvents and building blocks exhibit a coassembly manner. By specific treatments such as heating and cooling, solvents could be released or re-entrapped, allowing a smart control over supramolecular chirality. The solvent effect in manipulating two-dimensional chiral self-assemblies is then discussed. The perspective and future development in this research field are presented at last., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The field of covalent organic frameworks (COFs) has been developed significantly in the past decade on account of their important characteristics and vast application potential. On the other hand, the discovery of novel synthetic methodology is still a challenging task to further promote the preparation of COFs. Herein, an interesting protocol for the conversion of amorphous nonporous covalent organic polymers (COPs) to COFs was established, affording four COFs with high crystallinity and porosity. Specifically, imine-linked amorphous COP-1 was successfully converted to COF-1-4 by replacing one type of linker with other organic building blocks. The realization of this conversion provides a facile method for constructing COFs from COPs., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The attractive properties of layered inorganic materials, which make them suitable for numerous applications in chemical industries and life sciences, originated from their crystalline framework structures. Here, we report a new layered germanate PKU-21, which was prepared by the hydrothermal synthesis method using 2-propanolamine (MIPA) as the structure-directing agent. The structure of PKU-21 was determined from synchrotron single-crystal X-ray diffraction and synchrotron powder X-ray diffraction data. It reveals a complicated framework structure containing 18 unique Ge atoms in the asymmetric unit. PKU-21 is the first layered germanate built from both Ge 7 and Ge 10 clusters, following the 3-dimensional germanate PKU-17. The preparation and structure of PKU-21 are discussed in comparison with PKU-17, which provides new insight into the formation mechanism of germanates. Gas sorption experiments indicate that the layered PKU-21 sample exhibits a better CO 2 sorption selectivity over N 2 and CH 4 at 298 K than at 273 K, making it a promising candidate for CO 2 separation., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A one-step multipurpose strategy is developed to realize a sophisticated design that simultaneously integrates three desirable components of nitrogen dopant, 3D graphene, and 1D mesoporous metal oxide nanowires into one hybrid material. This facile synthetic strategy includes a one-step hydrothermal reaction followed by topotactic calcination. The utilization of urea as the starting reagent enables the precipitation of precursor nanowires and concurrent doping of nitrogen heteroatoms on graphene during hydrothermal reaction, while at the same time the graphene nanosheets are self-assembled to afford a 3D scaffold. Detailed characterizations on the final calcined product are conducted to confirm the phase purity, porosity, nitrogen composition, and morphology. The integration of two building blocks, i.e., flexible graphene nanosheets and Co3 O4 nanowires, enables various intertwining behaviors such as seaming, bridging, hooping, bundling, and sandwiching, of which synergistic effect substantially enhances electrical and electrochemical properties of the resultant hybrid. For lithium ion battery application of the hybrid, a remarkably high capacity more than 1200 mA h g(-1) (at 100 mA g(-1) ) is stabilized over 100 cycles with coulombic efficiency higher than 97%. Even during rapid discharge/charge processes (1000 mA g(-1) ), a reversible charge capacity of 812 mA h g(-1) is still retained after 230 cycles., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

As an emerging class of porous crystalline materials, covalent organic frameworks (COFs) are excellent candidates for various applications. In particular, they can serve as ideal platforms for capturing CO2 to mitigate the dilemma caused by the greenhouse effect. Recent research achievements using COFs for CO2 capture are highlighted. A background overview is provided, consisting of a brief statement on the current CO2 issue, a summary of representative materials utilized for CO2 capture, and an introduction to COFs. Research progresses on: i) experimental CO2 capture using different COFs synthesized based on different covalent bond formations, and ii) computational simulation results of such porous materials on CO2 capture are summarized. Based on these experimental and theoretical studies, careful analyses and discussions in terms of the COF stability, low- and high-pressure CO2 uptake, CO2 selectivity, breakthrough performance, and CO2 capture conditions are provided. Finally, a perspective and conclusion section of COFs for CO2 capture is presented. Recent advancements in the field are highlighted and the strategies and principals involved are discussed., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)