A Brick-Wall Topological 2D Covalent Organic Framework Constructed from an H-Shaped "Two-in-One" Monomer.

As an emerging class of porous crystalline material, covalent organic frameworks (COFs) have received considerable research interests in terms of exploring new architectures and functions. Herein, we developed an unprecedented "H-shaped" monomer, upon self-polycondensation, which facilely produced a benzoimidazole-based COF (H-BIm-COF) with a rarely reported brick-wall topology. H-BIm-COF displayed high crystallinity, nano-sized porosity, and high thermal and chemical stabilities. Interestingly, H-BIm-COF based membranes showed selective permeability towards different solvents, which related to the size and polarity of the guest molecule. Additionally, initial study suggested the COF displayed excellent rejection efficiency towards ionic dyes, for example chromium black T (99.7 %) and rhodamine B (97.3 %). This work provides insights into developing new topological COFs by designing monomers with new configurations.

Triangular Heteroporous Covalent Organic Framework via a K-Shaped "Two-in-One" Monomer: Targeted Synthesis and Selective Removal of Organic Pollutants.

Covalent organic frameworks (COFs) have attracted increasing research interest due to their intriguing topological structures and fascinating properties. Diverse COFs with different shapes and sizes are developed by the design of appropriate building blocks. However, the heteroporous COFs to date are still in their infancy due to the relatively limited configuration of precursors. Herein, it is ingeniously designed and synthesized a new K-shaped "two-in-one" building unit (3',6'-bis(4-(5,5-dimethyl-1,3-dixoan-2-yl)phenyl)-[1,1':2',1"-terphenyl]-4,4"-diamine, BPTD), thus realizing the construction of triangular dual microporous COF (BPTD-COF) via self-polycondensation of the K-shaped monomer. The super micropore (0.76 nm) of BPTD-COF endows the higher density of amine activity sites, while the other aperture size (1.35 nm) meets the need for accommodating cationic dyes (rhodamine B, methylene blue), thus BPTD-COF displays a distinctive selective adsorption for cationic dyes with good reusability.

Nickel Glyoximate Based Metal-Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Evolution.

Metal-covalent organic frameworks (MCOFs) have been recently received wide attention owing to the homogeneous distribution of active metal centers that are beneficial for enhancing the application potentials. However, metal complex based functional building blocks for MCOFs synthesis are limited. Herein, two new MCOFs (Ni-Py-COF and Ni-Bn-COF) were constructed via a novel nickel glyoximate based building block. Splendid photocatalytic activity on hydrogen evolution from water and great long-term recyclability were achieved using these nickel glyoximate based MCOFs as photocatalysts. Excitingly, even without the addition of Pt co-catalyst, the hydrogen evolution rates (HER) of Ni-Py-COF reached up to 626 µmol g-1 h-1 , which is better than many porous organic polymers. This work not only expands the type of building units for MCOFs, but also provides meaningful insights for developing stable, efficient and earth-abundant photocatalysts toward H2 generation.

Superhydrophilic 2D Covalent Organic Frameworks as Broadband Absorbers for Efficient Solar Steam Generation.

The intrinsic hydrophobicity and limited light absorption especially in the near-infrared (NIR) region of porous organic polymers are two bottlenecks impeding their applications in solar steam generation (SSG). Herein, we develop a 1,4,5,8-tetrakis(phenylamino)anthracene-9,10-dione (TPAD)-based covalent organic framework (COF) (TPAD-COF) featuring both superhydrophilicity and broad light absorption covering from the entire UV/Vis to NIR regions for SSG. TPAD-COF serving as a highly efficient photothermal conversion material without any additives displays an excellent water evaporation of 1.42 kg m-2 h-1 and achieves a high energy conversion efficiency of 94 % under 1 sun irradiation. Further extension of the light absorption range of the TPAD-based COF is realized through post-synthetic modification by chelating BF2 moieties. Systematic control experiments and analysis confirm that the hydrophilicity of photothermal conversion materials plays a more dominant role in the current TPAD-based COFs for SSG.

Multiscale Workflow for Modeling Ligand Complexes of Zinc Metalloproteins.

Zinc metalloproteins are ubiquitous, with protein zinc centers of structural and functional importance, involved in interactions with ligands and substrates and often of pharmacological interest. Biomolecular simulations are increasingly prominent in investigations of protein structure, dynamics, ligand interactions, and catalysis, but zinc poses a particular challenge, in part because of its versatile, flexible coordination. A computational workflow generating reliable models of ligand complexes of biological zinc centers would find broad application. Here, we evaluate the ability of alternative treatments, using (nonbonded) molecular mechanics (MM) and quantum mechanics/molecular mechanics (QM/MM) at semiempirical (DFTB3) and density functional theory (DFT) levels of theory, to describe the zinc centers of ligand complexes of six metalloenzyme systems differing in coordination geometries, zinc stoichiometries (mono- and dinuclear), and the nature of interacting groups (specifically the presence of zinc-sulfur interactions). MM molecular dynamics (MD) simulations can overfavor octahedral geometries, introducing additional water molecules to the zinc coordination shell, but this can be rectified by subsequent semiempirical (DFTB3) QM/MM MD simulations. B3LYP/MM geometry optimization further improved the accuracy of the description of coordination distances, with the overall effectiveness of the approach depending upon factors, including the presence of zinc-sulfur interactions that are less well described by semiempirical methods. We describe a workflow comprising QM/MM MD using DFTB3 followed by QM/MM geometry optimization using DFT (e.g., B3LYP) that well describes our set of zinc metalloenzyme complexes and is likely to be suitable for creating accurate models of zinc protein complexes when structural information is more limited.

Topology modulation of 2D covalent organic frameworks via a "two-in-one" strategy.

Topology modulation of covalent organic frameworks (COFs) still remains barely explored, probably due to the lack of appropriate building blocks. A "two-in-one" strategy applies bifunctional monomers to endow ideal stoichiometry and has recently demonstrated great potential in the facile preparation of highly crystalline two-dimensional (2D) COFs with different topologies. Herein, we employ this approach to modulate the topology of 2D COFs by varying the solvents or the monomer concentrations. To our delight, 2D COFs featuring a Kagome (kgm) lattice with both hexagonal and triangular dual pores (DP) or featuring a rhombic square (sql) single pore (SP) structure can be selectively formed by varying the solvents. Furthermore, adjusting the monomer concentrations also successfully tuned the topology of the COFs. In addition, the highly porous dual-pore COF showed potential applications for controlled drug delivery.

Arylamine-Linked 2D Covalent Organic Frameworks for Efficient Pseudocapacitive Energy Storage.

The development of new linkages is one of the most efficient strategies to enrich the diversity of covalent organic frameworks (COFs). Particularly, functional linkages can endow COFs with additional tailored properties besides the building units, which further diversify COFs with desirable functions. Herein, we have developed a new arylamine linkage for the construction of COFs. Two new arylamine-linked COFs (AAm-TPB and AAm-Py) were prepared by condensing cost-effective dimethyl succinyl succinate (DMSS) with corresponding multitopic amines (TPB-NH2 and Py-NH2 ). Due to the abundant electroactive diphenylamine moieties in the COF skeletons resembling that of polyaniline (PANI), a state-of-the-art conductive polymer, the pseudocapacitive energy storage performance of AAm-TPB was further investigated. Remarkably, the AAm-TPB electrode exhibits a high capacitance of 271 F g-1 with a three-electrode setup at a discharge rate of 1 A g-1 , which represents one of the highest capacitances among the reported COF-based electrode materials.

Sulfonated 2D Covalent Organic Frameworks for Efficient Proton Conduction.

Open 1D channels found in covalent organic frameworks are unique and promising to serve as pathways for proton conduction; how to develop high-rate yet stable transporting systems remains a substantial challenge. Herein, this work reports a strategy for exploring proton-conducting frameworks by engineering pore walls and installing proton-containing polymers into the pores. Amide-linked and sulfonated frameworks were synthesized from imine-linked precursors via sequentially engineering to oxidize into amide linkages and to further anchor sulfonic acid groups onto the pore walls, enabling the creation of sulfonated frameworks with high crystallinity and channel ordering. Integrating sulfonated polyether ether ketone chains into the open channels enables proton hopping to across the channels, greatly increases proton conductivity and enables a stable continuous run. These results suggest a way to explore proton-conducting COFs via systematic engineering of the wall and space of the open nanochannels.

Stable 2D Heteroporous Covalent Organic Frameworks for Efficient Ionic Conduction.

Two-dimensional (2D) covalent organic frameworks (COFs) feature open and ordered one-dimensional column nanochannels which offer immense possibilities for incorporation of various guests for specific functions. However, the relatively low chemical stability of most COFs originating from the dynamic covalent linkages hinders their practical application. In this work, a highly crystalline and heteroporous dibenzo[g,p]chrysene-based COF (DBC-2P) was synthesized and served as a host material for ionic conduction. DBC-2P exhibits excellent stability both in strong acid and base due to the large conjugated DBC-based knot that reinforces the interlayer interactions. Subsequent encapsulation of linear polyethylene glycol (PEG) and PEG-LiBF4 salt into the nanochannels of DBC-2P affords a hybrid material with a high ionic conductivity of 2.31×10-3  S cm-1 . This work demonstrates an efficient post-synthetic strategy for the development of new COF-polymer composites with intriguing properties.

Are the patients with anatomic variation of the sublingual/Wharton's duct system predisposed to ranula formation?

OBJECTIVE: To evaluate ranula development according to anatomic variation of the ductal system of sublingual gland (SLG), especially the presence of Bartholin's duct. METHODS: The anatomic variation of SLG duct was prospectively investigated and compared between 55 consecutive patients with ranulas treated by SLG excision (group 1) and another 15 consecutive patients undergoing similar surgeries for other conditions (group 2). The ductal structures of SLGs and submandibular glands (SMG) were also compared between the pediatric patients and adult patients with ranulas. RESULTS: In 32 of 55 patients with ranulas (58.2%) and 1 of 15 patients without ranulas (6.7%), the SLG showed an anatomic variation of the main duct called Bartholin's duct structure (P<0.01). Seventeen of 22 (77.3%) pediatric patients with ranulas had Bartholin's ducts and 15 of 33 (45.5%) adult patients with ranulas had Bartholin's ducts (0.01