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1.
Front Neurol ; 12: 759099, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34721280

RESUMO

Background and Purpose: To determine the feasibility of time-resolved angiography with stochastic trajectories (TWIST) in the diagnosis of spinal dural arteriovenous fistula (SDAVF) and perimedullary arteriovenous fistula (PAVF). Methods: A total of 11 negative patients with TWIST examination were retrospective analyzed and then 18 patients with suspected spinal vascular diseases underwent TWIST. For negative patients, Adamkiewicz artery (AKA), great anterior radiculomedullary vein (GARV) and anterior spinal artery (ASA) were retrospective analyzed. In patients, the results of TWIST were compared with those of DSA. Results: The displaying rates of the ASA, AKA and GARV in 11 negative patients were 100, 90.9, and 90.9%, respectively. The AKA and GARV were separated on TWIST. Of 18 patients, 11 and three were diagnosed with SDAVF and PAVF, respectively. The spinal cord vascular malformation diagnosed on TWIST was consistent with DSA with an excellent intermodality agreement (Kappa = 0.92, p < 0.001). The feeding artery and side of all 11 SDAVF patients were displayed on TWIST and the results were consistent with DSA. For PAVF patients, the feeding artery in two patients and the sides as displayed on TWIST were consistent with DSA. Conclusions: TWIST enables the differentiation of the spinal artery and vein and the differential diagnosis of SDAVF and PAVF.

2.
Angew Chem Int Ed Engl ; 60(28): 15466-15471, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-33871131

RESUMO

A Cp*-Rh based D-shaped binuclear metallacycle and a template-free molecular Borromean ring (BR) were obtained in high yield using the semi-rigid thioether dipyridyl ligand 1,4-bis[(pyridin-4-ylthio)methyl]benzene (Bptmb). The topological transformation from a binuclear metallacycle and a BR to tetranuclear metallacycles was realized via the controlled oxidation of thioethers. The strategy used in this work can be regarded as a new form of stimuli-responsive post-synthesis modification (PSM).

3.
Dalton Trans ; 49(28): 9688-9693, 2020 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32613982

RESUMO

The supramolecular assembly, used as a molecular reactor, is of great significance in host-guest chemistry. In this work, we used a tetratopic pyridyl ligand as a building block to hierarchically combine a slightly twisted cuboid with half-sandwich rhodium fragments. The cuboid directionally self-assembled hydrophobic pockets that can encapsulate conjugated molecules like anthracene (ANT) as guests in solutions, by supramolecular interactions including hydrogen bonding and hydrophobic interactions. The array of the ANT molecules in the confined pockets was subjected to a [4 + 4] photocycloaddition reaction under UV light irradiation as an external stimulus in a methanol solution. Furthermore, the mechanism underlying the process was proposed. The cuboid was fully characterized by 1H NMR, single-crystal X-ray diffraction (SCXRD), and mass spectrometry (MS), and its host-guest and cycloaddition processes were monitored by 1H NMR spectroscopy and UV-visible spectrophotometry.

4.
Dalton Trans ; 46(46): 16321-16326, 2017 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-29143044

RESUMO

The development of an earth-abundant, first-row water oxidation catalyst that operates at a high TOF and a low overpotential remains a fundamental chemical challenge. Cobalt complexes are important members of water oxidation catalysts. Herein, we report a cobalt-based robust homogeneous water oxidation catalyst, which can electrocatalyze water oxidation at a high pH and a low overpotential (η = 520 mV) in phosphate buffer. This homogeneous system exhibits a high turnover frequency (about 5 s-1) of catalyzing water oxidation to produce oxygen at η = 720 mV. We speculate the mechanism of the reaction that O-O bond formation prefers a HO-OH coupling in catalytic water oxidation.

5.
Dalton Trans ; 44(1): 351-8, 2015 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-25382024

RESUMO

A new azo-complex [(L)Cu(II)(NO3)] [L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)], was prepared via a one-pot synthetic method at 60 °C and was structurally characterized by IR, EA, PXRD and single crystal X-ray diffraction. In addition, TGA studies indicated that the complex was stable in air. The redox properties were determined by cyclic voltammetry, which revealed that the complex could be utilized as a catalyst for water oxidation under mild conditions. Subsequently, the complex was employed as a catalyst to take part in water oxidation reaction in the presence of a Ce(IV) salt utilized as an oxidant at pH 11 in PBS (Phosphate Buffered Saline) solution. The results suggested that the catalyst exhibited a high stability and activity toward water oxidation reaction under these conditions with an initial TOF of 4.0 kPa h(-1). Calculation methodology was performed to study the mechanism of the reaction, which revealed that in this catalytic process, the initial oxidation of Cu(II) to Cu(III) occurred by the formation of an intermediate "Cu(III)-O-O-Cu(III)". The formation of this intermediate, resulted in a release of oxygen and closing of the catalytic cycle.


Assuntos
Compostos Azo/química , Complexos de Coordenação/química , Cobre/química , Naftalenos/química , Água/química , Catálise , Modelos Moleculares , Oxirredução
6.
Chem Asian J ; 10(1): 239-46, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25303729

RESUMO

The binuclear [η(6) -(cymene)Ru(L)]2 (OTf)2 (TfO(-) =trifluoromethanesulfonate) and tetranuclear [η(6) -(cymene)Ru(L)]4 (NO3 )4 metallacycles were prepared by treating the pyridyl-substituted 8-hydroxyquinoline ligand (E)-2-[2-(pyridin-3-yl)vinyl]quinolin-8-ol (HL) with [(p-cymene)Ru(µ-Cl)Cl]2 in the presence of AgOTf or AgNO3 . The molecular structures of these complexes were confirmed by single-crystal X-ray diffraction, which revealed that both complexes have macrocycle frameworks induced by the TfO(-) and NO3 (-) counteranions, respectively. The electrochemical properties of the two metallacycles were investigated by cyclic voltammetry, which showed that they have great potential as catalysts for water oxidation. Good efficiency was obtained by utilizing the nitrate complex as a water oxidation catalyst in the presence of a Ce(IV) salt as an oxidant at high pH values.

7.
Dalton Trans ; 43(32): 12221-7, 2014 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-24828473

RESUMO

Herein we report the molecular structures and electronic properties of ionic, hydrophobic half-sandwich complexes with formula [η(5)-Cp*Ir(L)(Cl)](OTf) (), [η(5)-Cp*Rh(L)(Cl)](OTf) (), [η(5)-Cp*Ir(L)(H2O)](OTf)2 () and [η(5)-Cp*Rh(L)(H2O)](OTf)2 (), where L is 1-(2-pyridylazo)-2-naphthol. The electrochemical properties of these complexes have been investigated, and they displayed good electronic properties for use as water oxidation catalysts. Interestingly, the color of their solutions is unambiguously transformed from brown to green at pH = 12; the color changes of , and are especially apparent. For this reason, their use as pH sensors for detecting solution pH values can be explored.

8.
Dalton Trans ; 43(17): 6561-6, 2014 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-24626311

RESUMO

Herein we report the molecular structures and electronic properties of ionic, hydrophobic, half-sandwich complexes of the formula [η(5)-Cp*Rh(L)(MeOH)] (1) and [η(6)-CyRu(L)(H2O)] (2), where L is azo-dye compound of (p-(2-hydroxy-1-naphthylazo)benzenesulfonic acid sodium salt). Both these complexes have been investigated electrochemically and found to display good electronic properties for use as water-oxidation catalysts potentially.

9.
J Am Chem Soc ; 136(7): 2825-32, 2014 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-24471709

RESUMO

One-pot reactions of carborane carboxylic acids (L), [Cp*IrCl2]2, and silver salt are reported, which lead to regioselective B-H or C-H bond activation at ambient temperature in good yields. This process is demonstrated for three carborane (o-, m-, p-) dicarboxylates, and metal-mediated B-H functionalization of a p-carborane derivative is accomplished for the first time. Two metal-induced self-assembly routes to tetra-nuclear metallacycles 3 and 5 were performed through B(4, 7)/H and B(2, 10)/H activation, respectively, and the two metallacycles were found to be stable and to exist in solution as discrete complexes. Different activation modes in the carborane cage were ascribed to the characteristic structure of the products and the electronic density differences. The analogous reaction of o-carborane monocarboxylate with the same metal precursor gave the C-H activation complex 6, indicating that the B-H bond is more stable than the C-H bond in this carborane cage. The selective activation was confirmed by DFT calculation results. In this study, a facile and efficient synthetic route has been developed through specific B-H bond activation to construct carborane-based metallacycles that are unavailable by conventional methods.

10.
Chemistry ; 17(6): 1863-71, 2011 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-21254267

RESUMO

A series of binuclear complexes [{Cp*Ir(OOCCH(2)COO)}(2)(pyrazine)] (1b), [{Cp*Ir(OOCCH(2)COO)}(2)(bpy)] (2b; bpy=4,4'-bipyridine), [{Cp*Ir(OOCCH(2)COO)}(2)(bpe)] (3b; bpe=trans-1,2-bis(4-pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)(2)(OOC-C=C-COO)(pyrazine)}(2)] (1c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpy)}(2)] (2c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpe)}(2)] (3c), and [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](pyrazine)}(2)] (1d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpy)}(2)] (2d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpe)}(2)] (3d) were formed by reactions of 1a-3a {[(Cp*Ir)(2)(pyrazine)Cl(2)] (1a), [(Cp*Ir)(2)(bpy)Cl(2)] (2a), and [(Cp*Ir)(2)(bpe)Cl(2)] (3a)} with malonic acid, fumaric acid, or H(2)ADB (azobenzene-4,4'-chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self-assembled by activation of C-H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3c was converted to [2+2] cycloaddition complex 4. The molecular structures of 2b, 1c, 1d, and 4 were characterized by single-crystal x-ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1c, 1d, and 4. All complexes were well characterized by (1)H NMR and IR spectroscopy, as well as elemental analysis.

11.
Chem Soc Rev ; 38(12): 3419-34, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20449060

RESUMO

Over the past decade, supramolecular compounds with organometallic Ir, Rh, Ru based half-sandwich complexes have received considerable attention as materials with a variety of potential applications. The major emphasis of this tutorial review lies on the self-assembly of such organometallic half-sandwich molecular rectangles, prisms and cages with half-sandwich corners and two different rigid bifunctional ligands using an approach of stepwise construction. Synthetic methods and the structural and functional properties of the target complexes are discussed in detail.


Assuntos
Irídio/química , Compostos Macrocíclicos/síntese química , Compostos Organometálicos/síntese química , Rênio/química , Rutênio/química , Compostos Macrocíclicos/química , Estrutura Molecular , Compostos Organometálicos/química
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