Search

Developing efficient, inexpensive and robust heterogeneous catalysts for CO2 conversion is greatly important. In this study, a new stable copper(II)-based metal-organic framework [Cu(Fbtx)2Br2]n (denoted as CZU-7, CCDC-2165700, Fbtx = 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene) was synthesized via a facile and fast microwave heating method. CZU-7 exhibits a two-dimensional layer structure with the 44-sql topology. This material was demonstrated to be an efficient heterogeneous catalyst for the direct carboxylation of 1-ethynylbenzene with CO2, and various propiolic acids were synthesized in moderate to good yields under optimized reaction conditions. Moreover, the catalyst could be easily recovered and reused five times without significant loss of catalytic activity.

ObjectivesOrganotropism is primarily determined by tumor-derived exosomes. To date, the role of lung cancer cells-derived exosomes underlying the pre-metastatic niche formation is unclear.Materials and MethodsThe animal models of retro-orbital and intra-ventricular injection were constructed to administrate lung cancer cells-derived exosomes. Cytokine array was used to screen the cytokines released from brain endothelium after internalization of lung cancer cells-derived exosomes. The cellular co-culture system was established to mimic microglia-vascular niche contained lung cancer cells-derived exosomes. The levels of Dkk-1 and the activities of microglia were analyzed by qRT-PCR, western blot and immunofluorescence. In vivo selections of highly brain metastatic cells were performed to analyze the direct interaction of lung cancer cells with microglia.ResultsAnimal studies demonstrated that there was a suppressive signal transferred from brain endothelium to microglia after internalization of lung cancer cells-derived exosomes into brain endothelium, which caused an absolutely less M1 phenotypic microglia and a relatively more M2 phenotypic microglia. Further results indicated that lung cancer cells-derived exosomes induced a release of endogenous Dkk-1 from brain endothelium, which rendered microglia to acquire a pro-tumorigenic feature in pre-metastatic niche. Subsequently, the declines of Dkk-1 in metastatic lung cancer cells removed the suppression on microglia and enhanced microglial activation in metastatic niche.ConclusionOur findings shed a new light on the synergistic reaction of the different cells in “neurovascular units” toward the metastatic messages from lung cancer cells and provided a potential therapeutic pathway for lung cancer metastasis to brain.

In the title compound, C18H12F4N2S2, a bis-thiophenyl Schiff base ligand with a perifluorinated aromatic core, the complete molecule is generated by crystallographic inversion symmetry. The thiophene and tetrafluorinated benzene rings are oriented at a dihedral angle of 77.38 (4)°. The crystal structure exhibits C—H...F hydrogen bonds, resulting in supramolecular chains along the c-axis direction.

The title compound, C20H16F4N2S2, is a flexible bisthiophene-type Schiff base ligand with a perfluorinated backbone. The terminal thiophene rings are almost normal to one another with a dihedral angle of 83.8 (2)°, and they are tilted to the central tetrafluorinated benzene ring with dihedral angles of 61.2 (2) and 77.7 (1)°. In the crystal, there are π–π interactions involving the benzene ring and the thiophene ring of a symmetry-related molecule with a centroid–centroid separation of 3.699 (3) Å.

Rotaviruses are a major etiologic agent of gastroenteritis in infants and young children worldwide. Since the latter of the 1990s, G3 human rotaviruses referred to as "new variant G3" have emerged and spread in China, being a dominant genotype until 2010, although their genomic evolution has not yet been well investigated.The complete genomes of 33 G3P[8] human rotavirus strains detected in Wuhan, China, from 2000 through 2013 were analyzed. Phylogenetic trees of concatenated sequences of all the RNA segments and individual genes were constructed together with published rotavirus sequences.Genotypes of 11 gene segments of all the 33 strains were assigned to G3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, belonging to Wa genogroup. Phylogenetic analysis of the concatenated full genome sequences indicated that all the modern G3P[8] strains were assigned to Cluster 2 containing only one clade of G3P[8] strains in the US detected in the 1970s, which was distinct from Cluster 1 comprising most of old G3P[8] strains. While main lineages of all the 11 gene segments persisted during the study period, different lineages appeared occasionally in RNA segments encoding VP1, VP4, VP6, and NSP1-NSP5, exhibiting various allele constellations. In contrast, only a single lineage was detected for VP7, VP2, and VP3 genes. Remarkable lineage shift was observed for NSP1 gene; lineage A1-2 emerged in 2007 and became dominant in 2008-2009 epidemic season, while lineage A1-1 persisted throughout the study period.Chinese G3P[8] rotavirus strains have evolved since 2000 by intra-genogroup reassortment with co-circulating strains, accumulating more reassorted genes over the years. This is the first large-scale whole genome-based study to assess the long-term evolution of common human rotaviruses (G3P[8]) in an Asian country.

In the title compound, C10H6F2N4, the Car—N bonds are slightly shortened with respect to a standard aniline C—N bond [1.3580 (16) and 1.3618 (16) versus 1.39 Å], thus indicating some π–π conjgation with the electron-acceptor CN groups. The molecule, except for two C atom of the ethylene bridge, is nearly planar, the largest deviation of the other non-H atoms from the mean plane being 0.309 (2) Å. The N—C—C—N torsion angle involving the ethylene bridge is 50.23 (18)°. In the crystal, molecules are connected by pairs of N—H...N hydrogen bonds into chains along [21-1].

In the crystal structure of the title compound, C12H13N6+·ClO4−, the cation, located about an inversion center, is monoprotonated, and one H atom is disordered over two sites on N atoms of the two triazole rings, each with an occupancy factor of 0.5. The perchlorate anion has C2 symmetry, the Cl atom and one O atom lying on the twofold rotation axis; the anion is thus disordered over two sites of equal occupancy. In the cation, the triazole ring makes a dihedral angle of 84.75 (7)° with the plane of the benzene ring. In the crystal, intermolecular N—H...N hydrogen bonding between the triazole and triazolium rings links the cations into a wave-like supramolecular chain. Weak intermolecular C—H...N and C—H...O hydrogen bonding is also present.

The title compound, C20H14F4N4, is a flexible bis-pyridine-type ligand with an extended fluorinated spacer group between the two pyridyl functions. The centroid of the central aromatic ring is situated on a crystallographic center of inversion. The dihedral angle between the pyridine ring and the central benzene ring is 63.85 (9)°. The crystal structure exhibits intermolecular C—H...F hydrogen-bonding interactions.

The title compound, C20H18N4, is a flexible 3,3′-bipyridyl-type ligand with a long spacer group between the two pyridyl functions. The molecule crystallizes around an inversion center, with one half-molecule in the asymmetric unit and a dihedral angle of 71.85 (8)° between the pyridine ring and the central benzene ring.

The synthesis of cyclic carbonates through cycloaddition reactions between epoxides and carbon dioxide (CO2) is an important industrial process. Metal-Organic Frameworks (MOFs) have functional and ordered pore structures, making them attractive catalysts for converting gas molecules into valuable products. One approach to enhance the catalytic activity of MOFs in CO2 cycloaddition reactions is to create open metal sites within MOFs. In this study, the amino-functionalized rare earth Gd-MOF (Gd-TPTC-NH2) and its ionic liquid composite catalysts (Gd-TPTC-NH-[BMIM]Br) were synthesized using 2'-amino-[1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid (H4TPTC-NH2) as the ligand. The catalytic performance of these two catalysts was observed in the cycloaddition reaction of CO2 and epoxides. Under the optimized reaction conditions, Gd-TPTC-NH-[BMIM]Br can effectively catalyze the cycloaddition reaction of a variety of epoxide substrates with good to excellent yields of cyclic carbonate products. Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, promote higher yields of cyclic carbonates due to the electron-withdrawing nature of Cl and Br substituents. Additionally, the Gd-TPTC-NH- [BMIM]Br catalyst demonstrated good recyclability and reproducibility, maintaining its catalytic activity without any changes in its structure or properties after five reuse cycles. [ABSTRACT FROM AUTHOR]

A series of new alkali-metal-based coordination polymers, [Li(H2IMDC)(H2O)]n (1), [Na2(H2IMDC)2(H3IMDC)2(H2O)4]n (2), and [K(H2IMDC)(H2O)]n (3), have been constructed under solvothermal conditions by using imidazole-4,5-dicarboxylic acid (H3IMDC) as ligand. The structure of the complexes has been determined by single-crystal X-ray diffraction and further characterized by elemental analyses, IR spectra, powder X-ray diffraction and thermogravimetric analyses. The single crystal Xray structural studies showed that their structural dimensionalities varying from 1-D zigzag chain, 2-D 44-sql network to 3-D 4,6-connected coordination framework are strongly governed by the ionic radii and coordination geometries of the metal cations. For the first time, the alkali-metal-based coordination polymers were demonstrated to be effective catalysts for the solvent-free ring-opening polymerization (ROP) of ɛ-caprolactone. The catalytic activity of complexes 1–3 depends on the metal cations, increasing in the order Li+ < Na+ < K+. [ABSTRACT FROM AUTHOR]

A new zinc(II)-based coordination polymer {[Zn(5-fip)(tdbpy)] · (DMF)}n (1) {5-H2fip = 5-fluoroisophthalic acid, tdbpy = 4,4'-(2,4,8,10-tetraoxaspiro[5.5]undecane- 3,9-diyl)bispyridine, DMF = dimethylformamide} has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that complex 1 shows a unique two-dimensional network architecture containing single-stranded [Zn(5-fip)]n and double-stranded helical [Zn(tdbpy)]n chains. The thermal and luminescence properties of complex 1 have also been studied. [ABSTRACT FROM AUTHOR]

Two new Cu(ii) coordination polymers [Cu(Fbtx)(H2btec)(H2O)2]n and {[Cu(Fbtx)(btec)0.5(H2O)2]·H2O}n have been synthesised by hydrothermal reactions of Cu(ii) nitrate with 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene (Fbtx) and 1,2,4,5-benzenetetracarboxylic acid (H4btec) under different pH conditions. The first complex has a two-dimensional four-connected layer structure with a 44-sql topology, whereas the second has a two-dimensional three-connected brick-wall network. The luminescence properties of the complexes in the solid state and their thermal stabilities have also been studied. [ABSTRACT FROM AUTHOR]

Alumina-supported potassium (K/Al2O3) catalysts using pseudo-boehmite as the precursor were prepared by the impregnation/calcination method, characterised by XRD, SEM, ICP, N2 adsorption/ desorption, CO2-TPD methods and TG analysis, and applied to the vapour-phase condensation of methyl propionate with trioxane to produce methyl methacrylate. The results showed the catalysts' properties to be mainly affected by the calcined temperature (TC) and the crystal structure. The sample calcined at 1100°C exhibited the highest catalytic activity when mixed phases were formed and provided the appropriate specific surface area (SBET) and surface basic properties. The effects of TC, K-loading and reaction conditions on the catalytic performance were also investigated in a fixed-bed reactor. The yield of methyl methacrylate attained 29.2 % under the optimised conditions, and the deactivated catalyst could be completely regenerated by calcination. [ABSTRACT FROM AUTHOR]

The spontaneous self-assembly reactions of 2,3,5,6-tetrafluorobenzenedicarboxylic acid (H2BDC-F4) with Ca(NO3)2·4H2O in different solvents resulted in the generation of hydrophilic 3D chiral and achiral Ca(II)-organic frameworks {[Ca4(BDC-F4)4(H2O)4]·4H2O}n (1) and [Ca(BDC-F4)(MeOH)2]n (2), respectively. Complex 1 exhibits higher water solubility compared to 2, and further dissolution of 1 in water results in a new achiral crystal, [Ca(BDC-F4)(H2O)4]n (3). All complexes have been characterized by elemental analysis, IR spectroscopy, and single-crystal and powder X-ray diffraction techniques. Complex 1 crystallizes in the tetragonal P41212 chiral space group and features a rare binodal 5-connected network, directed by a unique 3D chiral (10,3)-a water aggregation consisting of two distinct helical arrays. Complex 2 crystallizes in the space group C2/c and has a binodal 4-connected pts net. Complex 3 crystallizes in the space group P21/m and presents a 2D layer framework containing the unprecedented polymeric [CaII-H2O]n chain based on triple μ2-O aqua bridges. The structural discrepancies illustrate the solvent-induced effect on the construction and structural transformation of chiral and achiral coordination frameworks. Moreover, gas (N2 and CO2) adsorption studies show that the dehydrated framework 1a exhibits excellent selective CO2 gas uptake at 195 K. [ABSTRACT FROM AUTHOR]

A fluorinated bis(triazole) ligand, 1,4-bis(1,2,4-triazol-1-ylmethyl)-2,3,5,6-tetrafluorobenzene (Fbtz), was applied to coordinate with a series of MnII, CoII, FeII, and CuII ions, respectively. In comparison with its nonfluorinated analogue 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx), Fbtz is able to build six novel metal-organic frameworks by acting as a versatile bridge combining with the terminal chlorides (1-5) or acetates (6) ligands. The solid-state crystal structures of 1-6 are studied by single-crystal X-ray crystallography to form the following structures: 3D polymers [M(Fbtz)2Cl2]n (1: M = Mn, 2: M = Co), 1D double chain polymers {[M(Fbtz)2Cl2]∙CH2Cl2∙xH2O}n (3: M = Co, x = 1; 4: M = Fe, x = 2), {[Cu(Fbtz)2Cl2]∙4H2O}n (5), and a 1D double-stranded helical polymer {[Cu2(Fbtz)(OAc)2]∙2H2O}n (6). Conformations of Fbtz in 1-6 can be tuned as a result of varying the anions or solvent system, which ultimately form a series of novel coordination frameworks with different supramolecular architectures. The antibacterial activities of all complexes are investigated. Complexes 4 and 5 show a wide range of bactericidal activities to Gram positive (B. subtilis and S. aureus) and negative (E. coli and P. fluorescence) bacterial strains. The synergistic interactions of ligand isomerism and counteranions have profound effects on the supramolecular networks and properties. [ABSTRACT FROM AUTHOR]

A simple and environmentally benign one-pot synthesis of diaryl thioethers by coupling of arylboronic acids with potassium ethyl xanthogenate through a double arylation process has been developed. The aryl thiols were generated in situ, and the reactions proceeded smoothly to give the corresponding products in good to excellent yields under very mild conditions. [ABSTRACT FROM AUTHOR]

The article determines the hydrogen bond-directed supramolecular arrays in 4,4'-bipyridinium tetrachloroterepththalate dihydrate and bis(1,10-phenanthrolinium) tetrachloroterephthalate tetrachloroterephthalic acid trihydrate. It describes the bonds between carboxylate and pyridinium groups and the crystallization of tetrachloroterephthalic acid with phenanthroline. Also observed are the dihedral angles between the carboxylate/carboxyl groups and tetrachlorinated aromatic rings and the intermolecular link of the packing's neutral and dianionic moieties.

In the centrosymmetric molecule of the title compound, C20H14F4N4O2, the pyridine ring is twisted with respect to the benzene ring with a dihedral angle of 66.85 (10)°. In the crystal structure, molecules are linked by intermolecular hydrogen- bonding and C—H…π interactions. [ABSTRACT FROM AUTHOR]

The article presents the structure and composition of the compound N-(4-Methoxy-6-methyl-1,3,5-triazin-2-yl)- N-methyl-N'-(2,3,4-trifluorophenyl)urea. The formula of the structure is C13H12F3N5O2. The formula, an intramolecular N-H…F, N-…, C-H…O and hydrogen bonds C-H…N and staking interactions π-π along the a axis produce a columnar structure. Bioactivities like herbicidal, plant-growth regulatory, antitubercular and antibacterial activity can be seen in triazine group against Staphylococcus aureus and Escherichia coli.

The title compound, C20H14F4N4O2, is centrosymmetric. The dihedral angle between the pyridine and benzene ring is 64.8 (4)°. The crystal structure is stabilized by intermolecular N—H...O hydrogen bonding. [ABSTRACT FROM AUTHOR]