Reticular Chemistry Directed "One-Pot" Strategy to in situ Construct Organic Linkers and Zirconium-Organic Frameworks.

Zirconium-based metal-organic frameworks (Zr-MOFs) have emerged as one of the most studied MOFs due to the unlimited numbers of organic linkers and the varying Zr-oxo clusters. However, the synthesis of carboxylic acids, especially multitopic carboxylic acids, is always a great challenge for the discovery of new Zr-MOFs. As an alternative approach, the in situ "one-pot" strategy can address this limitation, where the generation of organic linkers from the corresponding precursors and the sequential construction of MOFs are integrated into one solvothermal condition. Herein, inspired by benzimidazole-contained compounds synthesized via reaction of aldehyde and o-phenylenediamine, tri-, tetra-, penta- and hexa-topic carboxylic acids and a series of corresponding Zr-MOFs can be prepared via the in situ "one-pot" method under the same solvothermal conditions. This strategy can be utilized not only to prepare reported Zr-MOFs constructed using benzimidazole-contained linkers, but also to rationally design, construct and realize functionalities of zirconium-pentacarboxylate frameworks guided by reticular chemistry. More importantly, in situ "one-pot" method can facilitate the discovery of new Zr-MOFs, such as zirconium-hexacarboxylate frameworks. The present study demonstrates the promising potential of benzimidazole-inspired in situ "one-pot" approach in the crystal engineering of structure- and property-specific Zr-MOFs, especially with the guidance of reticular chemistry.

Tuning and Directing Energy Transfer from the Blue to Near-Infrared Range in Multicomponent Metal-Organic Frameworks with seh Topology.

Luminescent metal-organic frameworks (MOFs) are emerging as one of several promising materials to study light-harvesting and energy-transfer processes. However, it is still a big challenge to tune and direct energy transfer in luminescent MOFs-based light-harvesting system. Herein, a series of new light-harvesting zinc-based luminescent MOFs with seh underlying topology were reported by successfully integrating 2,1,3-benzothiadiazole and its derivative-based carboxylic acids and pyridine-contained linkers into one structure. The strong spectra overlap between the emission and absorption spectra of carboxylic acids and pyridine-type linkers afforded an ideal platform to realize efficient energy transfer from the blue to near-infrared range. This work provides a novel approach to the rational design and synthesis of MOFs-based multicomponent light-harvesting materials with tunable energy transfer to mimic natural photosynthetic processes.

Size- and Emission-Controlled Synthesis of Full-Color Luminescent Metal-Organic Frameworks for Tryptophan Detection.

The development of nanoscaled luminescent metal-organic frameworks (nano-LMOFs) with organic linker-based emission to explore their applications in sensing, bioimaging and photocatalysis is of great interest as material size and emission wavelength both have remarkable influence on their performances. However, there is lack of platforms that can systematically tune the emission and size of nano-LMOFs with customized linker design. Herein two series of fcu- and csq-type nano-LMOFs, with precise size control in a broad range and emission colors from blue to near-infrared, were prepared using 2,1,3-benzothiadiazole and its derivative based ditopic- and tetratopic carboxylic acids as the emission sources. The modification of tetratopic carboxylic acids using OH and NH2 as the substituent groups not only induces significant emission bathochromic shift of the resultant MOFs, but also endows interesting features for their potential applications. As one example, we show that the non-substituted and NH2 -substituted nano-LMOFs exhibit turn-off and turn-on responses for highly selective and sensitive detection of tryptophan over other nineteen natural amino acids. This work sheds light on the rational construction of nano-LMOFs with specific emission behaviours and sizes, which will undoubtedly facilitate their applications in related areas.

A Microporous Metal-Organic Framework Incorporating Both Primary and Secondary Building Units for Splitting Alkane Isomers.

We demonstrate the assembly of a mononuclear metal center, a hexanuclear cluster, and a V-shaped, trapezoidal tetracarboxylate linker into a microporous metal-organic framework featuring an unprecedented 3-nodal (4,4,8)-c lyu topology. The compound, HIAM-302, represents the first example that incorporates both a primary building unit and a hexanuclear secondary building unit in one structure, which should be attributed to the desymmetrized geometry of the organic linker. HIAM-302 possesses optimal pore dimensions and can separate monobranched and dibranched alkanes through selective molecular sieving, which is of significant value in the petrochemical industry.

Reticular Chemistry with Art: A Case Study of Olympic Rings-Inspired Metal-Organic Frameworks.

Herein, we demonstrate the successful utilization of reticular chemistry as an excellent designing strategy for the deliberate construction of a zirconium-tetracarboxylate metal-organic framework (MOF) inspired by the Olympic rings. HIAM-4017, with an unprecedented (4,8)-c underlying net topology termed jcs, was developed via insightful reconstruction of the rings and judicious design of a nonsymmetric organic linker. HIAM-4017 exhibits high porosity and excellent chemical and thermal stability. Furthermore, excited-state intramolecular proton transfer (ESIPT) was achieved in an isoreticular MOF, HIAM-4018, with a large Stokes shift of 155 nm as a result of introducing the hydroxyl group to the linker skeleton to induce OH···N interactions. Such interactions were analyzed thoroughly by employing the time-dependent density functional theory (TD-DFT). Because of their good thermal and chemical stability, and strong luminescence, nanosized HIAM-4017 and HIAM-4018 were fabricated and used for Cr2O72- detection. Both MOFs demonstrate excellent sensitivity and selectivity. This work represents a neat example of building structure- and property-specific MOFs guided by reticular chemistry.

Customized Synthesis: Solvent- and Acid-Assisted Topology Evolution in Zirconium-Tetracarboxylate Frameworks.

Metal-organic frameworks (MOFs) demonstrate strong potential for various important applications due to their well tunable structures and compositions through metal and organic linker engineering. As an effective approach, topology evolution by controlling linker conformation has received considerable attention, where solvents and acids have crucial effects on structural formation. However, a systematic study of such effects remains under investigated. Herein, we carried out a methodical study on the topology evolution in Zr-MOFs directed by solvothermal conditions with various combinations of three common solvents and six different acids. As a result, three Zr-MOFs with different topologies, scu (HIAM-4007), scp (HIAM-4008), and csq (HIAM-4009), were obtained using the same Zr6-cluster and tetratopic carboxylate linker, in which structure diversity shows significant influence on their corresponding photoluminescence quantum yields. Further experiments revealed that the acidity of acids and the basicity of solvents strongly influenced the linker conformation in the resultant MOFs, leading to the topology evolution. Such a solvent- and acid-assisted topology evolution represents a general approach that can be used with other tetratopic carboxylate linkers to realize structural diversity. The present work demonstrates an effective structure designing strategy by controlling synthetic conditions, which may prove to be powerful for customized synthesis of MOFs with specific structure and functionality.

Full-Color Emission in Multicomponent Metal-Organic Frameworks via Linker Installation.

Herein, we demonstrate that linker installation (LI) through postsynthesis is an effective strategy to insert emissive second linkers into single-linker-based metal-organic frameworks (MOFs) to tune the emission properties of multicomponent MOFs. Full-color emission, including white-light emission, can be achieved via such a LI process.

A Zirconium-Organic Framework Constructed from Saddle-Shaped Tetratopic Carboxylate for High-Rate and -Efficiency Iodine Capture.

Metal-organic frameworks (MOFs) exhibit strong potential for applications in molecular adsorption and separation because of their highly tunable structures and large specific surface areas and have also been used for iodine capture. However, most works on MOF-based iodine capture focus on the adsorption capacity while taking little consideration of the capture rate and efficiency. Herein, we report the design of a saddle-shaped tetratopic carboxylic acid containing four thiophene groups (H4COTTBA) and the synthesis of a 4,8-connected flu-type zirconium MOF (HIAM-4014) using this linker. HIAM-4014 exhibits highly efficient iodine capture. The large cagelike pore structure, OH- groups on the unsaturated Zr6 clusters, electron-rich nature of the thiophene group in the linker, and high surface area are all attributed to the tetrahedral geometry of H4COTTBA, which endows HIAM-4014 with a relatively high iodine adsorption capacity of 2.50 g/g within 2 h and an equilibrium adsorption capacity of 2.68 g/g after 5 h. Coupled with a high elution ratio and great recyclability, HIAM-4014 is a good candidate for the efficient removal of waste iodine.

Comprehensive metabolomics analysis of key taste components in different varieties of table grapes.

Grapes are one of the world's largest fruit crops, which are rich in nutrients and taste. Summer Black, Gui Fei, Kyoho Grape, Giant Rose, Shine Muscat, and Rosario Bianco are the six most popular table grapes in Wuxi city, Jiangsu province. Owing to the lack of comprehensive investigations of metabolites in table grapes, the metabolic causes of differences in their taste are unknown. In this study, metabolites of six table grapes were profiled using ultra-high-performance liquid chromatography-Q-Exactive Orbitrap tandem mass spectrometry combined with multivariate analysis. Orthogonal partial least squares discriminant analysis discriminated among the metabolites of these varieties. Metabolic pathway analysis revealed that carbohydrate and amino acid metabolisms were highly conserved among these varieties. Our results suggest that the taste differences in the six table grape varieties can be explained by variations in composition and abundance of carbohydrates, organic acids, amino acids, and polyphenols. This study provides comprehensive insights into the underlying metabolic causes of taste variation in table grapes.

Linker Engineering toward Full-Color Emission of UiO-68 Type Metal-Organic Frameworks.

Luminescent metal-organic frameworks (LMOFs) demonstrate strong potential for a broad range of applications due to their tunable compositions and structures. However, the methodical control of the LMOF emission properties remains a great challenge. Herein, we show that linker engineering is a powerful method for systematically tuning the emission behavior of UiO-68 type metal-organic frameworks (MOFs) to achieve full-color emission, using 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids as luminescent linkers. To address the fluorescence self-quenching issue caused by densely packed linkers in some of the resultant UiO-68 type MOF structures, we apply a mixed-linker strategy by introducing nonfluorescent linkers to diminish the self-quenching effect. Steady-state and time-resolved photoluminescence (PL) experiments reveal that aggregation-caused quenching can indeed be effectively reduced as a result of decreasing the concentration of emissive linkers, thereby leading to significantly enhanced quantum yield and increased lifetime.

Creating an Aligned Interface between Nanoparticles and MOFs by Concurrent Replacement of Capping Agents.

Applying metal-organic frameworks (MOFs) on the surface of other materials to form multifunctional materials has recently attracted great attention; however, directing the MOF overgrowth is challenging due to the orders of magnitude differences in structural dimensions. In this work, we developed a universal strategy to mediate MOF growth on the surface of metal nanoparticles (NPs), by taking advantage of the dynamic nature of weakly adsorbed capping agents. During this colloidal process, the capping agents gradually dissociate from the metal surface, replaced in situ by the MOF. The MOF grows to generate a well-defined NP-MOF interface without a trapped capping agent, resulting in a uniform core-shell structure of one NP encapsulated in one single-crystalline MOF nanocrystal with specific facet alignment. The concept was demonstrated by coating ZIF-8 and UiO-66-type MOFs on shaped metal NPs capped by cetyltrimethylammonium surfactants, and the formation of the well-defined NP-MOF interface was monitored by spectroscopies. The defined interface outperforms ill-defined ones generated via conventional methods, displaying a high selectivity to unsaturated alcohols for the hydrogenation of an α,ß-unsaturated aldehyde. This strategy opens a new route to create aligned interfaces between materials with vastly different structural dimensions.

Tuning Metal-Organic Framework Nanocrystal Shape through Facet-Dependent Coordination.

We studied coordination-dependent surfactant binding on shaped MOF nanocrystals. Cetyltrimethylammonium bromide (CTAB) on the surface of ZIF-8 was used as a model system. Infrared spectroscopic analysis and molecular dynamics simulations reveal different coordination environments for Zn nodes on {100} and {110} facets, resulting in different CTAB adsorption. We found that we are able to fine-tune the ratio of {100} and {110} facets in the nanocrystals. We also observed that once the MOF nanocrystals are enclosed by pure {110} facets growth along the {100} facets is terminated because the MOF nanocrystal has no surface area for CTAB adsorption. Growth can then be reinitiated through the etching of these rhombic dodecahedral nanocrystals to form a small amount of undercoordinated sites. This work represents the first systematic study of the design principles underpinning the synthesis of shaped MOF nanocrystals.

Tuning and Directing Energy Transfer in the Whole Visible Spectrum through Linker Installation in Metal-Organic Frameworks.

While limited choice of emissive organic linkers with systematic emission tunability presents a great challenge to investigate energy transfer (ET) over the whole visible light range with designable directions, luminescent metal-organic frameworks (LMOFs) may serve as an ideal platform for such study due to their tunable structure and composition. Herein, five Zr6 cluster-based LMOFs, HIAM-400X (X=0, 1, 2, 3, 4) are prepared using 2,1,3-benzothiadiazole and its derivative-based tetratopic carboxylic acids as organic linkers. The accessible unsaturated metal sites confer HIAM-400X as a pristine scaffold for linker installation. Six full-color emissive 2,1,3-benzothiadiazole and its derivative-based dicarboxylic acids (L) were successfully installed into HIAM-400X matrix to form HIAM-400X-L, in which the ET can be facilely tuned by controlling its direction, either from the inserted linkers to pristine MOFs or from the pristine MOFs to inserted linkers, and over the whole range of visible light. The combination of the pristine MOFs and the second linkers via linker installation creates a powerful two-dimensional space in tuning the emission via ET in LMOFs.

Three Models To Encapsulate Multicomponent Dyes into Nanocrystal Pores: A New Strategy for Generating High-Quality White Light.

Highly luminescent metal-organic frameworks (LMOFs) have received great attention for their potential use in energy-efficient general lighting devices such as white-light-emitting diodes (WLEDs); however, achieving strong emission with controllable color, especially high-quality white light, remains a considerable challenge. Herein, we present a new strategy to encapsulate in situ multiple dyes into nanocrystalline ZIF-8 pores to form an efficient dyes@MOF system. Using this strategy, we build three models, namely, multiphase single-shell dye@ZIF-8, single-phase single-shell dyes@ZIF-8, and single-phase multishell dyes@ZIF-8, to systematically and fine-tune the white emission color by varying the components and concentration of encapsulated dyes. The study of these three models demonstrates the importance of the multishell structure, which can effectively reduce the interactions such as Förster resonance energy transfer (FRET) between encapsulated dyes. This energy transfer would otherwise be unavoidable in a single-shell setting, which often reduces the efficiency of white-light emission in the dyes@MOF system. This approach offers a new perspective not only for fine-tuning the emission color within nanoporous dyes@MOFs but also for fabricating MOF nanocrystals that are easily solution-processable. The strategy may also facilitate the development of other types of MOF-guest nanocomposite systems.

Quantifying Visible-Light-Induced Electron Transfer Properties of Single Dye-Sensitized ZnO Entity for Water Splitting.

Quantifying the photoinduced electron transfer properties of a single entity is of paramount importance for clarifying the link between the photoelectrochemical performance and the specific properties of an individual. Here, we successfully monitored the photoelectrochemical behavior of a single dye-sensitized ZnO entity on a Au ultramicroelectrode with different TiO2 film thicknesses. Due to a trap-limited electron diffusion in TiO2 film, a sub-millisecond photocurrent transient was observed for an individual N719@ZnO associated with single-particle photocatalytic water splitting. Furthermore, a Monte Carlo random walk numerical simulation model was developed to simulate the photoinjected electron transport dynamics and recombination in a nanoparticulate TiO2 film. Our approach allowed the photocatalytic properties of N719 at the single-molecule level to be quantified, and electron diffusivity and electron collection efficiency as a function of the film thickness were estimated by simulation analyses. Excellent agreement was obtained between the experimental results and theoretical simulations, indicating that the underlying photoinduced electron transfer processes can be reliably explored.

Using a Multi-Shelled Hollow Metal-Organic Framework as a Host to Switch the Guest-to-Host and Guest-to-Guest Interactions.

A bio-inspired design of using metal-organic framework (MOF) microcrystals with well-defined multi-shelled hollow structures was used as a matrix to host multiple guests including molecules and nanoparticles at separated locations to form a hierarchical material, mimicking biological structures. The interactions such as energy transfer (ET) between different guests are regulated by precisely fixing them in the MOF shells or encapsulating them in the cavities between the MOF shells. The proof-of-concept design is demonstrated by hosting chromophore molecules including rhodamine 6G (R6G) and 7-amino-4-(trifluoromethyl)coumarin (C-151), as well as metal nanoparticles (Pd NPs) into the multi-shelled hollow zeolitic imidazolate framework-8 (ZIF-8). We could selectively establish or diminish the guest-to-framework and guest-to-guest ET. This work provides a platform to construct complex multifunctional materials, especially those need precise separation control of multi-components.

Dynamic Self-Assembly of Homogenous Microcyclic Structures Controlled by a Silver-Coated Nanopore.

The self-assembly of nanoparticles is a challenging process for organizing precise structures with complicated and ingenious structures. In the past decades, a simple, high-efficiency, and reproducible self-assembly method from nanoscale to microscale has been pursued because of the promising and extensive application prospects in bioanalysis, catalysis, photonics, and energy storage. However, microscale self-assembly still faces big challenges including improving the stability and homogeneity as well as pursuing new assembly methods and templates for the uniform self-assembly. To address these obstacles, here, a novel silver-coated nanopore is developed which serves as a template for electrochemically generating microcyclic structures of gold nanoparticles at micrometers with highly homogenous size and remarkable reproducibility. Nanopore-induced microcyclic structures are further applied to visualize the diffusion profile of ionic flux. Based on this novel strategy, a nanopore could potentially facilitate the delivery of assembled structures for many practical applications including drug delivery, cellular detection, catalysis, and plasmonic sensing.

Transcriptomic analysis of two Beauveria bassiana strains grown on cuticle extracts of the silkworm uncovers their different metabolic response at early infection stage.

Beauveria bassiana is an important entomopathogenic fungus which not only widely distributes in the environment but also shows phenotypic diversity. However, the mechanism of pathogenic differences among natural B. bassiana strains has not been revealed at transcriptome-wide level. In the present study, in order to explore the mechanism, two B. bassiana strains with different pathogenicity were isolated from silkworms (Bombyx mori L.) and selected to analyze the gene expression of early stage by culturing on cuticle extracts of the silkworm and using RNA-sequencing technique. A total of 2108 up-regulated and 1115 down-regulated genes were identified in B. bassiana strain GXsk1011 (hyper-virulent strain) compared with B. bassiana strain GXtr1009 (hypo-virulent strain), respectively. The function categorization of differential expressed genes (DEGs) showed that most of them involved in metabolic process, biosynthesis of secondary metabolites, catalytic activity, and some involved in nutrition uptake, adhesion and host defense were also noted. Based on our data, distinct pathogenicity among different strains of B. bassiana may largely attribute to unique gene expression pattern which differed at very early infection process. Most of the genes involved in conidia adhesion, cuticle degradation and fungal growth were up-regulated in hyper-virulent B. bassiana strain GXsk1011. Furthermore, in combination with fungal growth analysis, our research provided a clue that fungal growth may also play an important role during early infection process. The results will help to explain why different B. bassiana strains show distinct pathogenicity on the same host even under same condition. Moreover, the transcriptome data were also useful for screening potential virulence factors.

Low-molecular-weight fibroblast growth factor 2 attenuates hepatic fibrosis by epigenetic down-regulation of Delta-like1.

UNLABELLED: Liver fibrosis, a major cause of end-stage liver diseases, is closely regulated by multiple growth factors and cytokines. The correlation of fibroblast growth factor 2 (FGF2) with chronic liver injury has been reported, but the exact functions of different FGF2 isoforms in liver fibrogenesis remain unclear. Here, we report on the differential expression patterns and functions of low- and high-molecular-weight FGF2 (namely, FGF2(lmw) and FGF2(hmw) , respectively) in hepatic fibrogenesis using a CCl4 -induced mouse liver fibrosis model. FGF2(hmw) displayed a robust increase in CCl4 -induced hepatic fibrosis and promoted fibrogenesis. In contrast, endogenous FGF2(lmw) exhibited a slight increase in hepatic fibrosis and suppressed this pathological progression. Moreover, exogenous administration of recombinant FGF2(lmw) potently ameliorated CCl4 -induced liver fibrosis. Mechanistically, we showed that FGF2(lmw) treatment attenuated hepatic stellate cell activation and fibrosis by epigenetic down-regulation of Delta-like 1 expression through the p38 mitogen-activated protein kinase pathway. CONCLUSION: FGF2(lmw) and FGF2(hmw) have distinct roles in liver fibrogenesis. These findings demonstrate a potent antifibrotic effect of FGF2(lmw) administration, which may provide a novel approach to treat chronic liver diseases.

Early intramedullary nailing for femoral fractures in patients with severe thoracic trauma: A systemic review and meta-analysis.

PURPOSE: Early intramedullary nailing (IMN) within the first 24 h for multiply injured patients with femoral fracture and concomitant thoracic trauma is controversial. Previously published studies have been limited in size and their outcomes have been inconclusive. A meta-analysis was conducted to evaluate the available data in order to guide care and help improve the outcomes for these patients. METHODS: We searched the literature up to December 2011 in the main medical search engines and identified 6 retrospective cohort studies that explored the safety of early IMN in patients with both femoral fracture and chest injury. Our primary outcome was the rates of pulmonary complication (pneumonia, adult respiratory distress syndrome, fat embolism syndrome), multiple organ failure (MOF) and mortality. RESULTS: We found no statistically significant difference in the rate of pulmonary complications, MOF or mortality in the patients treated with early IMN. CONCLUSION: Early IMN for femoral fractures does not increase the mortality and morbidity in chest- injured patients in the studies analyzed.