Structural Change and Radical Generation of a Cadmium-Based Metal-Organic Framework Induced by an Electric Field.

Herein we report the structural change and radical generation of a cadmium-based metal-organic framework (Cd-MOF) induced by external electric fields. Under a weaker single electric field, different coordination modes of Cd-L lead to 3D → 2D structural change. Under stronger superposed electric fields, Cd-MOF was excited to produce a stable free radical. This study will provide a new avenue for the controlled assembly of MOFs.

Cd-MOF: specific adsorption selectivity for linear alkyne (propyne, 2-butyne and phenylacetylene) molecules.

The selective adsorption of APPT-Cd-MOF 1 for propyne, 2-butyne and phenylacetylene was confirmed by single-crystal analysis. In addition, the selective adsorption performance of Cd-MOF for C3H4/C3H6/C3H8 was investigated. The matching of the functionality and size/shape between porous materials and guest molecules clarified the specific recognition of 1 for linear alkyne molecules.

Rational Design of High-Relaxivity EuII -Based Contrast Agents for Magnetic Resonance Imaging of Low-Oxygen Environments.

Metal-based contrast agents for magnetic resonance imaging present a promising avenue to image hypoxia. EuII -based contrast agents have a unique biologically relevant redox couple, EuII/III , that distinguishes this metal for use in hypoxia imaging. To that end, we investigated a strategy to enhance the contrast-enhancing capabilities of EuII -based cryptates in magnetic resonance imaging by controlling the rotational dynamics. Two dimetallic, EuII -containing cryptates were synthesized to test the efficacy of rigid versus flexible coupling strategies. A flexible strategy to dimerization led to a modest (114 %) increase in contrast enhancement per Eu ion (60 MHz, 298 K), but a rigid linking strategy led to an excellent (186 %) increase in contrast enhancement despite this compound's having the smaller molecular mass of the two dimetallic complexes. We envision the rigid linking strategy to be useful in the future design of potent EuII -based contrast agents for magnetic resonance imaging.

Photochromic Rhenium-Based Molecular Rectangles: Syntheses, Structures, Photophysical Properties, and Electrochemistry.

Two novel fac-Re(CO)3-based rectangles {[(CO)3Re(µ-Cl)2Re(CO)3]2(µ-L)2} (1) and {[(CO)3Re(µ-OC4H9)2Re(CO)3]2(µ-L)2}(2) based on new photochromic dithienylethene-containing ligand 2,7-di(pyridin-4-yl)-9,10-bis(5-chloro-2-methylthien-3-yl)-phenanthrene (L) were prepared. They displayed varying photochromic properties both in solution and in the single-crystal state. Through a judicious choice of the bridging ligands along the short sides of the rectangles, the photophysical and electrochemical properties of the complexes could also be readily tuned.

Syntheses of four porous 3-D Cd(ii) metal-organic frameworks from a new multidentate ligand 5-(imidazol-1-yl)-N'-(pyridin-4-ylmethylene) nicotinohydrazide and their characterization and adsorption properties.

Herein, a new multidentate ligand, 5-(imidazol-1-yl)-N'-(pyridin-4-ylmethylene) nicotinohydrazide (L), with an acylhydrazone group was synthesized and characterized. Subsequently, four porous Cd(ii)-MOFs, i.e. [Cd(L)(NO3)] n (1), [Cd(L)Cl] n (2), [Cd(L)Br] n (3), and [Cd(L)I] n (4), were assembled using the ligand L by a solvothermal method and characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Structural analysis shows that the coordination environments around Cd(ii) in all the four compounds are different due to the different coordinated anions. Among them, the coordination geometries and the arrangement of five-coordinated groups of the compound 1 containing the coordinated NO3 - anions are significantly different from those of the other three compounds containing halides. However, all the four MOFs have similar one-dimensional rhombic channels. In these channels, both the nitrate ions and the halide ions are attached to the inner walls of the pores. The CO2 adsorption properties of 1-4 were studied at 273 K, and the results showed that these compounds exhibit different adsorption capacities for CO2 due to the presence of different ions in their pores.

Three AgI, CuI and CdII coordination polymers based on the new asymmetrical ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole: syntheses, characterization and emission properties.

The new asymmetrical organic ligand 2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole (L, C17H13N5O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft AgI, CuI and CdII metal ions was investigated and three new coordination polymers (CPs), namely, catena-poly[[silver(I)-µ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole] hexafluoridophosphate], {[Ag(L)]PF6}n, catena-poly[[copper(I)-di-µ-iodido-copper(I)-bis(µ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)] 1,4-dioxane monosolvate], {[Cu2I2(L)2]·C4H8O2}n, and catena-poly[[[dinitratocopper(II)]-bis(µ-2-{4-[(1H-imidazol-1-yl)methyl]phenyl}-5-(pyridin-4-yl)-1,3,4-oxadiazole)]-methanol-water (1/1/0.65)], {[Cd(L)2(NO3)2]·2CH4O·0.65H2O}n, were obtained. The experimental results show that ligand L coordinates easily with linear AgI, tetrahedral CuI and octahedral CdII metal atoms to form one-dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π-π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.

[Ag-Ag]2+ Unit-Encapsulated Trimetallic Cages: One-Pot Syntheses and Modulation of Argentophilic Interactions by the Uncoordinated Substituents.

Four [Ag-Ag]2+ unit-encapsulated trimetallic cages 1-4 were synthesized from one new tripodal ligand L and silver salts in different solvent systems by a one-pot method. The formation of coordination cages occurred simultaneously with the condensation of amino groups and ketone. The remarkable structural feature of cages 1-4 is their spontaneous incorporation of [Ag-Ag]2+ cationic units. Moreover, the argentophilic interactions are modulated by the uncoordinated amino substituents. The study herein shows that modification and subtle changes of the cage structures could be realized by a one-pot synthetic method.

Visual Recognition and Removal of C2H2 from C2H4/C2H2 Mixtures by a CuI-MOF.

A CuI-MOF was found to be a highly selective visual sensor for recognizing C2H2. Gas chromatography studies indicated that it can be used to effectively remove minor amounts of C2H2 from C2H4/C2H2 mixtures (98:2) and produce highly pure C2H4 (nearly 100%).

Characterization and gas adsorption of a novel three-dimensional metal-organic framework (MOF) generated from a new polydentate fluorene-bridged ligand.

A polydentate ligand bridged by a fluorene group, namely 9,9-bis(2-hydroxyethyl)-2,7-bis(pyridin-4-yl)fluorene (L), has been prepared under solvothermal conditions in acetonitrile. Crystals of the three-dimensional metal-organic framework (MOF) poly[[[µ3-9,9-bis(2-hydroxyethyl)-2,7-bis(pyridin-4-yl)fluorene-κ3N:N':O]bis(methanol-κO)(µ-sulfato-κ2O:O')nickel(II)] methanol disolvate], {[Ni(SO4)(C27H24N2O2)(CH3OH)]·2CH3OH}n, (I), were obtained by the solvothermal reaction of L and NiSO4 in methanol. The ligand L forms a two-dimensional network in the crystallographic bc plane via two groups of O-H...N hydrogen bonds and neighbouring two-dimensional planes are completely parallel and stack to form a three-dimensional structure. In (I), the NiII ions are linked by sulfate ions through Ni-O bonds to form inorganic chains and these Ni-containing chains are linked into a three-dimensional framework via Ni-O and Ni-N bonds involving the polydentate ligand L. With one of the hydroxy groups of L coordinating to the NiII atom, the torsion angle of the hydroxyethyl group changes from that of the uncoordinated molecule. In addition, the adsorption properties of (I) with carbon dioxide were investigated.

Unique Eu(II) Coordination Environments with a Janus Cryptand.

Two new Eu(II)-containing cryptates were prepared with a new nitrogenous cryptand functionalized with three benzo groups. The introduction of three aromatic rings into the ligand backbone imparts lopsided geometrical features on the resulting Eu(II) coordination environments. In both complexes, the interactions between Eu and the amines on the aromatic side of the molecule are weaker than those on the nonaromatic side, resulting in one discrete unit with two distinct faces. One of the new complexes is, to the best of our knowledge, the first direct observation of a bis-aquo Eu(II)-containing cryptate with two nonadjacent inner-sphere water molecules. In addition to solid-phase structure, the electronic UV-visible and emission spectra of the new complexes were studied in acetonitrile. Experimental results show that the decreased Lewis basicity of the aromatic face hypsochromically shifts absorbances and emissions from a structurally related compound without the benzo groups.

[Dy(acac)3(dppn)]·C2H5OH: construction of a single-ion magnet based on the square-antiprism dysprosium(III) ion.

The present work reports a new mononuclear Dy(III) complex [Dy(acac)3(dppn)]·C2H5OH (1) (acac = acetylacetone, dppn = benzo[i]dipyrido-[3, 2-a:2',3'-c]phenazine). X-ray crystallography analysis reveals that compound 1 is a discrete molecular complex and the Dy(III) center lies in a square-antiprism coordination environment. Furthermore, complex 1 shows single-ion magnet (SIM) behavior. Compared to the reported complexes [Dy(dppz)(acac)3]·CH3OH, [Dy(dpq)(acac)3] and [Dy(phen)(acac)3], complex 1 exhibits a different energy barrier, which might be raised from the different coordination environment caused by the different auxiliary co-ligand dppn. The energy barrier variations of these Dy(III)-complexes are consistent with their square antiprism structural features.

Follow-Up of 58 Traumatic Carotid-Cavernous Fistulas after Endovascular Detachable-Balloon Embolization at a Single Center

BACKGROUND AND PURPOSE: This study evaluated the clinical value of detachable-balloon embolization for traumatic carotid-cavernous fistula (TCCF), focusing on the frequency, risk factors, and retreatment of recurrence. METHODS: Fifty-eight patients with TCCF underwent transarterial detachable-balloon embolization between October 2004 and March 2011. The clinical follow-up was performed every 3 months until up to 3 years postprocedure. Each patient was placed in either the recurrence group or the nonrecurrence group according to whether a recurrence developed after the first procedure. The relevant factors including gender, fistula location, interval between trauma and the interventional procedure, blood flow in the carotid-cavernous fistula, number of balloons, and whether the internal carotid artery (ICA) was sacrificed were evaluated. RESULTS: All 58 TCCFs were successfully treated with transarterial balloon embolization, including 7 patients with ICA sacrifice. Recurrent fistulas occurred in seven patients during the follow-up period. Univariate analysis indicated that the interval between trauma and the interventional procedure (p=0.006) might be the main factor related to the recurrence of TCCF. The second treatments involved ICA sacrifice in two patients, fistula embolization with balloons in four patients, and placement of a covered stent in one patient. CONCLUSIONS: Detachable balloons can still serve as the first-line treatment for TCCFs and recurrent TCCFs despite having a nonnegligible recurrence rate. Shortening the interval between trauma and the interventional procedure may reduce the risk of recurrence.

Value of percutanous catheter fragmentation in the management of massive pulmonary embolism / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Acute massive pulmonary embolism (PE) is a clinical emergency requiring rapid and supportive measures. Percutanous mechanical thrombectomy is considered as a treatment option. The purpose of this study was to evaluate the clinical efficacy and safety of peructaneous mechanical catheter fragmentation in the management of acute massive PE.</p><p><b>METHODS</b>From January 2003 to June 2007, 28 patients (20 men, 8 women; mean age 64 years) with acute massive PE initially diagnosed by computed tomography and confirmed by pulmonary angiography were treated with inferior vena caval filter placement and percutaneous catheter fragmentation. Twenty-six patients received thrombolytic agents after embolus fragmentation.</p><p><b>RESULTS</b>Technical success was achieved in all patients. The improvement of clinical status and restoration of blood flow in the main branches of the pulmonary artery were seen in 27 patients. Only one case did not benefit from the percutaneous therapy and died from the failure of the surgery. Oxygen saturation increased from (86.2 +/- 4.5)% to (96.1 +/- 3.2)% (P < 0.001) after the interventional procedure. The post-procedure mean pulmonary artery pressure decreased from (34.2 +/- 4.8) mmHg to (25.2 +/- 5.1) mmHg (P < 0.001). During clinical follow-up (range, 1 - 5 years), no patients had recurrence of PE.</p><p><b>CONCLUSION</b>Percutaneous catheter fragmentation combined with thrombolysis is an effective and safe therapy in the clinical management of acute massive PE.</p>

[Ag(2)(C(33)H(26)N(2)O(2))(H(2)O)(2)(SO(3)CF(3))(2)].0.5C(6)H(6): a luminescent supramolecular silver(I) complex based on metal-carbon and metal-heteroatom interactions.

A novel fulvene-type bidentate ligand 1 has been synthesized by an aroylation reaction of cyclohexyl-substituted cyclopentadienyl anions. Compound 1 crystallizes in the triclinic space group P(-)1, with a = 7.0419(5) A, b = 11.9360(8) A, c = 15.6470(11) A, alpha = 85.1440(10) degrees, beta = 78.1140(10) degrees, gamma = 74.5360(10) degrees, V = 1239.76(15) A(3), and Z = 2. The coordination chemistry of 1 was investigated, and a novel Ag-containing coordination polymer (2), linked by both Ag-heteroatom and Ag-carbon interactions, has been synthesized. The coordination polymer has been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Compound 2 crystallizes in the triclinic space group P(-)1, with a = 7.1654(5) A, b = 15.7277(11) A, c = 18.8157(13) A, alpha = 73.5150(10) degrees, beta = 89.0410(10) degrees, gamma = 89.0970(10) degrees, V = 1355.19(14) A(3), and Z = 2. The solid-state structure of 2 features a one-dimensional double-chain motif. These double chains are in turn cross-linked to each other via strong interchain O-H...O hydrogen bonds, forming a novel two-dimensional network with remarkably large cavities (effective cross section of ca. 21 x 15 A) that are occupied by benzene guest molecules. Both compounds 1 and 2 are luminescent in the solid state, and a large blue-shift in the emission between the free ligand 1 and the ligand incorporated into complex 2 is observed.