Crystalline nanosheets of three-dimensional supramolecular frameworks with uniform thickness and high stability.

Fabricating three dimensional (3D) supramolecular frameworks (SMFs) into stable crystalline nanosheets remains a great challenge due to the homogeneous and weak inter-building block interactions along 3D directions. Herein, crystalline nanosheets of a 3D SMF with a uniform thickness of 4.8 ± 0.

Single Cobalt Ion-Immobilized Covalent Organic Framework for Lithium-Sulfur Batteries with Enhanced Rate Capabilities.

Covalent organic frameworks (COFs) are notable for their remarkable structure, function designability, and tailorability, as well as stability, and the introduction of "open metal sites" ensures the efficient binding of small molecules and activation of substrates for heterogeneous catalysis and energy storage. Herein, we use the postsynthetic metal sites to catalyze polysulfide conversion and to boost the binding affinity to active matter for lithium-sulfur batteries (LSBs). A dual-pore COF, USTB-27, with topology has been successfully assembled from the imine chemical reaction between 2,3,8,9,14,15-hexa(4-formylphenyl)diquinoxalino [2,3-:2',3'-c]phenazine and [2,2'-bipyridine]-5,5'-diamine.

Nanostructurally Engineering Covalent Organic Frameworks for Boosting CO Photoreduction.

Herein, a series of imine-linked covalent organic frameworks (COFs) are developed with advanced ordered mesoporous hollow spherical nanomorphology and ultra-large mesopores (4.6 nm in size), named OMHS-COF-M (M = H, Co, and Ni). The ordered mesoporous hollow spherical nanomorphology is revealed to be formed via an Ostwald ripening mechanism based on a one-step self-templated strategy.

Observation of Interpenetrated Topology Isomerism for Covalent Organic Frameworks with Atom-Resolution Single Crystal Structures.

Rational control and understanding of isomerism are of significance but still remain a great challenge in reticular frameworks, in particular, for covalent organic frameworks (COFs) due to the complicated synthesis and energy factors. Herein, reaction of 3,3',5,5'-tetra(4-formylphenyl)-2,2',6,6'-tetramethoxy-1,1'-biphenyl (TFTB) with 3,3',5,5'-tetrakis(4-aminophenyl)bimesityl (TAPB) under different reaction conditions affords single crystals of two 3D COF isomers, namely, USTB-20-dia and USTB-20-qtz. Their structures with resolutions up to 0.

Linkage conversions in single-crystalline covalent organic frameworks.

Single-crystal X-ray diffraction is a powerful characterization technique that enables the determination of atomic arrangements in crystalline materials. Growing or retaining large single crystals amenable to it has, however, remained challenging with covalent organic frameworks (COFs), especially suffering from post-synthetic modifications. Here we show the synthesis of a flexible COF with interpenetrated qtz topology by polymerization of tetra(phenyl)bimesityl-based tetraaldehyde and tetraamine building blocks.

Cofacial porphyrin organic cages. Metals regulating excitation electron transfer and CO reduction electrocatalytic properties.

Herein, we introduce a comprehensive study of the photophysical behaviors and CO reduction electrocatalytic properties of a series of cofacial porphyrin organic cages (CPOC-M, M = H, Co(ii), Ni(ii), Cu(ii), Zn(ii)), which are constructed by the covalent-bonded self-assembly of 5,10,15,20-tetrakis(4-formylphenyl)porphyrin (TFPP) and chiral (2-aminocyclohexyl)-1,4,5,8-naphthalenetetraformyl diimide (ANDI), followed by post-synthetic metalation. Electronic coupling between the TFPP donor and naphthalene-1,4 : 5,8-bis(dicarboximide) (NDI) acceptor in the metal-free cage is revealed to be very weak by UV-vis spectroscopic, electrochemical, and theoretical investigations. Photoexcitation of CPOC-H, as well as its post-synthetic Zn and Co counterparts, leads to fast energy transfer from the triplet state porphyrin to the NDI unit according to the femtosecond transient absorption spectroscopic results.

Reticular Synthesis of Metal-Organic Frameworks by 8-Connected Quadrangular Prism Ligands for Water Harvesting.

Utilization of rigid, highly connected organic linkers is critical for the reticular synthesis of functional metal-organic frameworks (MOFs). However, highly-stable MOFs (e.g.

Highly Connected Three-Dimensional Covalent Organic Framework with Flu Topology for High-Performance Li-S Batteries.

Lithium-sulfur batteries (LSBs) have been considered as a promising candidate for next-generation energy storage devices, which however still suffer from the shuttle effect of the intermediate lithium polysulfides (LiPSs). Covalent-organic frameworks (COFs) have exhibited great potential as sulfur hosts for LSBs to solve such a problem. Herein, a pentiptycene-based symmetrical octatopic polyaldehyde, 6,13-dimethoxy-2,3,9,10,18,19,24,25-octa(4'-formylphenyl)pentiptycene (DMOPTP), was prepared and utilized as a building block toward preparing COFs.

A Configurationally Confined Thermally Activated Delayed Fluorescent Two-Coordinate Cu Complex for Efficient Blue Electroluminescence.

Thermally activated delayed fluorescence (TADF) from linear two-coordinate coinage metal complexes is sensitive to the geometric arrangement of the ligands. Herein we realize the tuning of configuration from coplanar to orthogonal gradually by variation of substituents. In a complex with confined twist configuration, its blue emission peaking at 458 nm presents a high Φ of 0.

Conjugated Three-Dimensional High-Connected Covalent Organic Frameworks for Lithium-Sulfur Batteries.

Developing conjugated three-dimensional (3D) covalent organic frameworks (COFs) still remains an extremely difficult task due to the lack of enough conjugated 3D building blocks. Herein, condensation between an 8-connected pentiptycene-based building block (DMOPTP) and 4-connected square-planar linkers affords two 3D COFs (named 3D-scu-COF-1 and 3D-scu-COF-2). A combination of the 3D homoaromatic conjugated structure of the former building block with the 2D conjugated structure of the latter linking units enables the π-electron delocalization over the whole frameworks of both COFs, endowing them with excellent conductivities of 3.

Hydrogen-Bonded Organic Framework Ultrathin Nanosheets for Efficient Visible-Light Photocatalytic CO Reduction.

Post-modification of robust guanine-quadruplex-linked 2,2'-pyridine-containing HOF-25 with Ni(ClO )  ⋅ 6 H O followed by exfoliation using sonication method affords hydrogen-bonded organic framework (HOF) nanosheets (NSs) of HOF-25-Ni in the yield of 56 %. TEM and AFM technologies disclose the ultrathin nature of HOF-25-Ni NSs with thickness of 4.4 nm.

Transformation of Porous Organic Cages and Covalent Organic Frameworks with Efficient Iodine Vapor Capture Performance.

The reaction of 5,5'-([2,2'-bipyridine]-5,5'-diyl)diisophthalaldehyde (BPDDP) with cyclohexanediamine and [benzidine (BZ)/[2,2'-bipyridine]-5,5'-diamine (BPDA)], respectively, affords a nitrogen-rich porous organic cage BPPOC and two two-dimensional (2D) covalent organic frameworks (COFs), USTB-1 and USTB-2 (USTB = University of Science and Technology Beijing), under suitable conditions. Interestingly, BPPOC with a single-crystal X-ray diffraction structure is able to successfully transform into USTB-1 and USTB-2 (newly converted COFs denoted as USTB-1c and USTB-2c, respectively) upon exchange of the imine unit of cyclohexanediamine in the cage by BZ and BPDA. Such a transformation also enables the isolation of analogous COFs (USTB-3c and USTB-4c) on the basis of an isostructural organic cage, BTPOC, which is derived from 5,5'-([2,2'-bithiophene]-4,4'-diyl)diisophthalaldehyde (BTDDP) and cyclohexanediamine.

Porphyrin Coordination Polymer with Dual Photocatalytic Sites for Efficient Carbon Dioxide Reduction.

The resurgence of visible light photocatalysis for carbon dioxide reduction reaction (CORR) has resulted in the generation of various homogeneous and heterogeneous paradigms. Herein, a new system has been established by incorporating dual catalytic sites into porous coordination polymer toward the photocatalysis of CORR. A functional ligand, 5,10,15,20-tetrakis[4'-(terpyridinyl)phenyl]porphyrin (TTPP), has been used to assemble discrete divalent nickel ions into the coordination polymer (TTPP-Ni) through metal bis(terpyridine) nodes.

Stimuli-Responsive Porous Molecular Crystal with Reversible Modulation of Porosity.

Responsive materials have received much attention due to modulated properties under stimuli such as light, heat, and electricity. A photoresponsive porous molecular crystal () has been assembled from a racemic dithienylethene-cage (L) by multiple C-F···H-C hydrogen bonds and van der Waals forces according to crystallographic investigation. Electronic absorption spectroscopy reveals reversible photochromic behaviors of the solution and film forms of enantiomeric L upon UV and visible light irradiation due to photoisomerization of dithienylethene units.

Maximizing Electroactive Sites in a Three-Dimensional Covalent Organic Framework for Significantly Improved Carbon Dioxide Reduction Electrocatalysis.

Synthesis of functional 3D COFs with irreversible bond is challenging. Herein, 3D imide-bonded COFs were constructed via the imidization reaction between phthalocyanine-based tetraanhydride and 1,3,5,7-tetra(4-aminophenyl)adamantine. These two 3D COFs are made up of interpenetrated pts networks according to powder X-ray diffraction and gas adsorption analyses.

A Solid Transformation into Carboxyl Dimers Based on a Robust Hydrogen-Bonded Organic Framework for Propyne/Propylene Separation.

Self-assembly of N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine with the help of different solvents provides isostructural hydrogen-bonded organic frameworks (HOF-30). Single-crystal X-ray diffraction (SCXRD) analysis reveals HOF-30 possesses 3D ten-fold interpenetrated dia nets connected by two kinds of hydrogen bonds, namely solvent-bridged carboxyl dimers and carboxyl⋅⋅⋅carboxyl dimers. Degassing treatment for HOF-30 yields HOF-30a with 3D ten-fold interpenetrated dia nets but linked with sole carboxyl⋅⋅⋅carboxyl dimers.

Rational Modification of Two-Dimensional Donor-Acceptor Covalent Organic Frameworks for Enhanced Visible Light Photocatalytic Activity.

Covalent organic frameworks (COFs) are promising crystalline materials for photocatalytic solar- to hydrogen-energy conversion due to the tunable chemical structures and energy band gaps. Herein, we report a chemical modification strategy for improving the photocatalytic activity of COFs. A benzene-1,3,5-tricarbaldehyde (BT)- and benzothiadiazole derivative-based two-dimensional donor-acceptor (D-A) COF, denoted as BT-COF, were fabricated and further modified by using an alternative electron-donating unit, 2-hydroxybenzene-1,3,5-tricarbaldehyde (HBT), to the polycondensation reaction, yielding HBT-COF with an enhanced internal D-A effect and hydrophilicity.

Two-Dimensional Covalent Organic Frameworks with Cobalt(II)-Phthalocyanine Sites for Efficient Electrocatalytic Carbon Dioxide Reduction.

The rapid development in synthesis methodology and applications for covalent organic frameworks (COFs) has been witnessed in recent years. However, the synthesis of highly stable functional COFs still remains a great challenge. Herein two-dimensional polyimide-linked phthalocyanine COFs (denoted as CoPc-PI-COF-1 and CoPc-PI-COF-2) have been devised and prepared through the solvothermal reaction of the tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato cobalt(II) with 1,4-phenylenediamine and 4,4'-biphenyldiamine, respectively.

Robust Biological Hydrogen-Bonded Organic Framework with Post-Functionalized Rhenium(I) Sites for Efficient Heterogeneous Visible-Light-Driven CO Reduction.

A robust 2,2'-bipyridine (bpy)-derived biological hydrogen-bonded framework (HOF-25) has been realized depending on guanine-quadruplex with the assistance of π-π interaction, which reacts with Re(CO) Cl to give a post-functionalized HOF-25-Re. X-ray absorption fine structure spectroscopic study on HOF-25-Re confirms the covalent attachment of Re(bpy)(CO) Cl segments to this HOF. Robust and recycled HOF-25-Re bearing photocatalytic Re(bpy)(CO) Cl centers displays good heterogeneous catalytic activity towards carbon dioxide photoreduction in the presence of [Ru(bpy) ]Cl and triisopropanolamine in CH CN under visible-light irradiation, with both high CO production rate of 1448 μmol g  h and high selectivity of 93 %.