Effects and mechanisms of FBXO31 on Taxol chemoresistance in esophageal squamous cell carcinoma.

Taxol is commonly used chemotherapy regimen for esophageal squamous cell carcinoma (ESCC). Study of the underlying mechanisms of Taxol chemoresistance provides better understanding of esophageal cancer treatment and may provide a rational molecular target for diagnosis and intervention. Here we showed FBXO31, which was reported to be highly expressed in ESCC and significantly associated with poor prognosis, could regulate ESCC chemosensitivity to Taxol. Silencing of FBXO31 in ESCC cells sensitized cells to Taxol treatment, evidenced by FACS analysis and TUNEL assay, showing as an increased apoptotic population in FBXO31-knockdown cells compared to the control cells. The mass spectrometry data and coimmunoprecipitation results showed FBXO31 could bind with cofilin-1. Cofilin-1 knockdown in FBXO31-overexpression cells reversed FBXO31-induced suppression of cell apoptosis, suggesting FBXO31-mediated Taxol chemoresistance is associated with cofilin-1. Furthermore, in vivo experiments confirmed that knockdown of FBXO31 sensitized ESCC to Taxol treatment. This finding substantiated a pivotal role of FBOX31 in ESCC chemoresistance, indicating that FBXO31 may be a potential indicator or target for drug resistance in ESCC.

The crucial roles of guest water in a biocompatible coordination network in the catalytic ring-opening polymerization of cyclic esters: a new mechanistic perspective.

The ring-opening polymerization (ROP) of cyclic esters/carbonates is a crucial approach for the synthesis of biocompatible and biodegradable polyesters. Even though numerous efficient ROP catalysts have been well established, their toxicity heavily limits the biomedical applications of polyester products. To solve the toxicity issues relating to ROP catalysts, we report herein a biocompatible coordination network, CZU-1, consisting of Zn4(µ4-O)(COO)6 secondary building units (SBUs), biomedicine-relevant organic linkers and guest water, which demonstrates high potential for use in the catalytic ROP synthesis of biomedicine-applicable polyesters. Both experimental and computational results reveal that the guest water in CZU-1 plays crucial roles in the activation of the Zn4(µ4-O)(COO)6 SBUs by generating µ4-OH Brønsted acid centers and Zn-OH Lewis acid centers, having a synergistic effect on the catalytic ROP of cyclic esters. Different to the mechanism reported in the literature, we propose a new reaction pathway for the catalytic ROP reaction, which has been confirmed using density functional theory (DFT) calculations, in situ diffuse reflectance IR Fourier transform spectroscopy (DRIFTS), and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS). Additionally, the hydroxyl end groups allow the polyester products to be easily post-modified with different functional moieties to tune their properties for practical applications. We particularly expect that the proposed catalytic ROP mechanism and the developed catalyst design principle will be generally applicable for the controlled synthesis of biomedicine-applicable polymeric materials.

Assembly of 1D, 2D and 3D lanthanum(iii) coordination polymers with perchlorinated benzenedicarboxylates: positional isomeric effect, structural transformation and ring-opening polymerisation of glycolide.

Utilizing a series of positional isomers of tetrachlorinated benzenedicarboxylic acid ligands, seven La(iii)-based coordination polymers were solvothermally synthesized and structurally characterized. Their structural dimensionalities varying from 1D double chains, to the 2D 3,4,5-connected network, to 3D 6-connected pcu topological nets are only governed by the positions of carboxyl groups on the tetrachlorinated benzene ring. A comprehensive analysis and comparison reveals that the size of the carbonyl solvent molecules (DMF, DEF, DMA, and NMP) can affect the coordination geometries around the La(iii) ions, the coordination modes of carboxylate groups, the packing arrangements, and the void volumes of the overall crystal lattices. One as-synthesized framework further shows an unprecedented structural transformation from a 3D 6-connected network to a 3D 4,5-connected net through the dissolution and reformation pathway in water, suggesting that these easily hydrolyzed lanthanide complexes may serve as precursors to produce new high-dimensional frameworks. The bulk solvent-free melt polymerisation of glycolide utilizing these La(iii) complexes as initiators has been reported herein for the first time. All complexes were found to promote the polymerization of glycolide over a temperature range of 200 to 220 °C, producing poly(glycolic acid) (PGA) with a molecular weight up to 93,280. Under the same experimental conditions, the different catalytic activities for these complexes may result from their structural discrepancy.

Crystal structure of catena-poly[[di-aqua-cadmium(II)]-µ-3,3'-(1,3-phenyl-ene)diacrylato].

In the crystal of the title polymeric complex, [Cd(C12H8O4)(H2O)2] n , the Cd(II) cation, located on a twofold rotation axis, is coordinated by two water mol-ecules and chelated by two phenyl-enediacrylate anions (mpda) in a distorted octa-hedral geometry. The mpda anions bridge the Cd(II) cations, forming helical chains propagating along the c-axis direction. The mpba anion has twofold symmetry with two benzene C atoms located on the twofold rotation axis. In the crystal, O-H⋯O hydrogen bonds link the polymeric helical chains into a three-dimensional supra-molecular architecture.

Doping potassium ions in silver cyanide complexes for green luminescence.

Doping potassium ions in silver cyanide complexes leads to two heterometallic silver-potassium cyanide complexes, namely, [Me4N]2[KAg3(CN)6] (1) with a typical NaCl-type framework containing distinct ligand-unsupported argentophilic interactions, and [Ag3(H2O)3][K(CN)2]3 (2) with an unprecedented 3-D (4,4,6,6)-connected framework formed by unique [Ag3(H2O)3] clusters connecting concave-convex [K(CN)2] layers. The two complexes exhibit green luminescence, and the relationships between their structures and photoluminescence, as well as the regulating effect on the luminescence by doping of potassium ions are well investigated via density functional theory analysis.

Poly[diaqua-[µ6-4,4'-(1,4-phenyl-ene)bis-(2,6-dimethyl-pyridine-3,5-dicarboxyl-ato)]dilead(II)].

The asymmetric unit of the title Pb-based coordination polymer, [Pb2(C24H16N2O8)(H2O)2] n , consists of one Pb(II) cation, half of a 4,4'-(1,4-phenyl-ene)bis-(2,6-dimethyl-pyridine-3,5-di-carb-oxyl-ate (L (4-)) ligand and one coordinating water mol-ecule. The centers of the benzene ring of the ligand and the four-membered Pb/O/Pb/O ring are located on centers of inversion. The Pb(II) ion is coordinated in form of a distorted polyhedron by seven O atoms from four separate L (4-) ligands and by one water O atom. The PbO7 polyhedra share O atoms, forming infinite zigzag [PbO4(H2O)] n chains along [100] that are bridged by L (4-) ligands, forming a two-dimensional coordination network parallel to (001). O-H⋯O hydrogen bonds involving the water mol-ecule are observed.

Distinct chiral units from an axially prochiral ligand in a photoluminescent zinc(II)-organic complex.

The asymmetric unit of the title compound, poly[(dimethylamine-κN)[µ(3)-(E)-2,6-dimethyl-4-styrylpyridine-3,5-dicarboxylato-κ(3)O(3):O(3'):O(5)]zinc(II)], [Zn(C(17)H(13)NO(4))(C(2)H(7)N)](n), consists of one crystallographically independent distorted tetrahedral Zn(II) cation, one (E)-2,6-dimethyl-4-styrylpyridine-3,5-dicarboxylate (mspda(2-)) ligand and one coordinated dimethylamine molecule. Two S- and R-type chiral units are generated from the axially prochiral mspda(2-) ligand through C-H...O hydrogen bonds. The R-type chiral units assemble a left-handed (M) Zn-mspda helical chain, while the right-handed (P) Zn-mspda helical chain is constructed from neighbouring S-type chiral units. The P- and M-type helical chains are interlinked by carboxylate O atoms to form a one-dimensional ladder. Interchain N-H...O hydrogen bonds extend these one-dimensional ladders into a two-dimensional supramolecular architecture. The title compound exhibits luminescence at λ(max) = 432 nm upon excitation at 365 nm.

A binuclear zinc polymer with paddlewheel building units and intersecting helical chains based on a flexible 4-[(carboxymethyl)sulfanyl]benzoic acid ligand.

The asymmetric unit of the title compound, poly[{µ(4)-4-[(carboxylatomethyl)sulfanyl]benzoato}(N,N-dimethylformamide)zinc], [Zn(C(9)H(6)O(4)S)(C(3)H(7)NO)](n), consists of one crystallographically independent Zn(II) cation, one 4-[(carboxylatomethyl)sulfanyl]benzoate (L(2-)) ligand and one coordinated dimethylformamide (DMF) molecule. The zinc ion is coordinated by five O atoms from four separate L(2-) ligands and one DMF molecule, and the ZnO(5) unit displays a distorted square-based-pyramidal geometry. Two ZnO(5) units form a binuclear zinc-tetracarboxylate paddlewheel cluster, and these are bridged by L(2-) ligands to generate an intersecting helical chain (Zn(2+) ions as nodes), which is composed of right-handed (P) and left-handed (M) helices. Weak C-H···O hydrogen bonds extend the one-dimensional coordinated chain into a weakly bound three-dimensional supramolecular architecture.

Transformation from [W6O19](2-) to [W6O22](8-) stabilized by Cu(II) complexation.

A rare [W6O22](8-) fragment has been first captured in aqueous solution of [W6O19](2-) by using a transition-metal complex and isolated as a new compound [Cu4(W6O22)(L1)2(H2O)2]·2H2O (1; L1 = 2-amino-4,6-bis(2-pyridyl)pyrimidine), indicating that [W6O19](2-) could also transform to [W6O22](8-) in aqueous solution besides the earlier proven ψ-metatungstates, [W10O32](4-), ß-[(H2)W12O40](6-) and [W7O24](6-).

A 12-connected dodecanuclear copper cluster with yellow luminescence.

The 3-D 12-connected metal-organic framework [Cu(12)Br(2)(CN)(6/2)(SCH(3))(6)][Cu(SCH(3))(2)], containing dodecanuclear copper clusters, has been solvothermally synthesized and exhibits efficient yellow luminescence. The emission mechanism was studied in detail to elucidate the relationship of the luminescent properties and crystal structures, which is helpful for the design and synthesis of more efficient luminescent materials.

Lanthanide-organic cation frameworks with zeolite gismondine topology and large cavities from intersected channels templated by polyoxometalate counterions.

A family of organic-inorganic hybrid frameworks, {[Ln(H(2)O)(4)(pdc)](4)} [XMo(12)O(40)].2H(2)O (Ln = La, Ce, and Nd; X = Si and Ge; H(2)pdc = pyridine-2,6-dicarboxylate), have been prepared under hydrothermal conditions and characterized by single crystal X-ray diffraction analyses, elemental analyses, IR, and thermal gravimetric analyses. Single crystal X-ray diffraction reveals that all six compounds are isostructural, and each consists of a zeolite-like four-connected three-dimensional cationic framework {[Ln(H(2)O)(4)(pdc)](4)}(4+) and ball-shaped Keggin type [XMo(12)O(40)](4-) as templates. Interesting channels exist in the cationic framework with the gismondine topology, and these channels intersect each other to form large cavities, which array in a zigzag fashion and are occupied by nanosized [XMo(12)O(40)](4-) counterions. Moreover, these compounds display strong photoluminescent properties in the solid state at room temperature.

A new two-dimensional supramolecule composed of mu-2,6-dimethylpyridine-3,5-dicarboxylato-kappa4O3,O3':O5,O5'-bis[chloro(1,10-phenanthroline-kappa2N,N')zinc(II)].

In the binuclear title molecule, [Zn(2)(C(9)H(7)NO(4))Cl(2)(C(12)H(8)N(2))(2)], the two metal centres are bridged by a 2,6-dimethylpyridine-3,5-dicarboxylate ligand. The binuclear unit is extended to form a two-dimensional supramolecular motif via pi-pi stacking interactions between neighbouring phenanthroline rings.

Structural diversity of silver(I) 4,6-dipyridyl-2-aminopyrimidine complexes: effect of counteranions and ligand isomerism.

Using two ligands, 4,6-bis(2-pyridyl)-2-aminopyrimidine (L1) with two N,N'-chelating sites and 4-(2-pyridyl)-6-(4-pyridyl)-2-aminopyrimidine (L2) (as the isomer of L1) containing one chelating site and one bridging unit, a series of novel Ag(I) complexes varying from zero- to two-dimensions have been prepared and their crystal structures determined via single-crystal X-ray diffraction. The two ligands are employed for the first time in coordination chemistry. The structures of compounds 1-3 are directed by the counteranions adopted in the reaction system: The reaction of L1 with AgNO3 yielded a dimer [Ag2L12](NO3)2 (1). The reaction of L1 with AgCF3SO3 led to a one-dimension "V-shaped" chain {[AgL1](CF3SO3)}n (2). When AgSCN was used, a one-dimension ladder {[Ag2L1(SCN)2].H2O}n (3) was obtained. While ligand L2 reacted with AgNO3, a two-dimension {[Ag2(L2)2](NO3)2.H2O}n (4) was prepared with the help of an argentophilic interaction. Compounds 1-4 display room-temperature photoluminescence.