Self-selected formation of single discrete supramolecules with flexible, bidentate ligands in the coordination-driven self-assembly

Journal ArticleFlexible donor ligands like 1,2-bis(3-pyridyl)ethyne or 1,4-bis(3-pyridyl)-1,3-butadiyne selfassemble into discrete 2-D supramolecules instead of infinite networks upon combination with organoplatinum 90, 120, and 180 degree acceptor units. These systems are unique examples of versatile pyridine donors adjusting their bonding directionality to accommodate rigid platinum acceptors in the formation of closed macrocycles. Discrete, nanoscopic 3-D cages are also prepared in high yield via coordination-driven self-assembly from bidentate 3-substituted pyridines and tripod organoplatinum acceptors. Flexible, bidentate 3-substituted pyridine donors and a rigid organopalladium acceptor are also exclusively selfassembled into discrete 2-D macrocycles. Moreover, discrete supramolecules are successfully prepared from ambidentate donor ligands and platinum containing acceptors. Despite the possibility of forming more than one product, ambidentate ligands prefer to self-assemble predominantly into one species. Flexible, ambidentate pyridyl-carboxylate based donor ligands like sodium 3-(3-pyridyl)benzoate, sodium 4-(3-pyridyl)benzoate and potassium 4-(3-pyridyl)ethynylbenzoate self-assemble into discrete [2+2] macrocyclic species instead of infinite networks when combined with a 90 degree organoplatinum acceptor. In each case only one isomeric ensemble is selectively formed in high yield. All products are characterized by electrospray ionization mass spectrometry (ESI-MS), 31P{1H} and 1H NMR spectroscopy. They are the first examples of discrete supramolecules incorporating flexible, bidentate donor ligands. Despite their potential versatility, these flexible donors adjust their bonding directionality to accommodate a rigid acceptor in the formation of one discrete ensemble

Incorporation of flexible pyridine-functionalized ligands into discrete supramolecules via coordination-driven self-assembly

Journal ArticleFlexible, pyridine-functionalized ligands were self-assembled into discrete supramolecules of differing stoichiometries upon combination with various organoplatinum molecules. They are characterized by electrospray ionization mass spectrometry, 31P(iHI and 'H NMR. Despite its inherent flexibility, 3-substituted pyridines 1 and di-pynrdyl substituted 18-membered diaza-crown ligand 8 prefer to self-assemble into closed systems when reacted with platinum-containing acceptors

Простой и эффективный метод диазотирования-иодирования ароматических аминов в водных пастах под действием систем: NaNO[2]/п-толуолсульфокислота и NaNO[2]/NaHSO[4]

Предлагается новый, удобный и эффективный метод получения ароматических иодидов из анилинов реакцией диазотирования-иодирования под действием NaNO[2]/KI/p-TsOH или NaHSO[4] при 20 °С в водной пасте. Разработанный метод отвечает требованиям "зеленой химии", предъявляемым к современным химическим процессам

Cilostazol Prevents Tumor Necrosis Factor-␣-Induced Cell Death by Suppression of Phosphatase and Tensin Homolog Deleted from Chromosome 10 Phosphorylation and Activation of Akt/Cyclic AMP Response Element-Binding Protein Phosphorylation

ABSTRACT This study examines the signaling mechanism by which cilostazol prevents neuronal cell death. Cilostazol (ϳ0.1-100 M) prevented tumor necrosis factor-␣ (TNF-␣)-induced decrease in viability of SK-N-SH and HCN-1A cells, which was antagonized by 1 M iberiotoxin, a maxi-K channel blocker. TNF-␣ did not suppress the viability of the U87-MG cell, a phosphatase and tensin homolog deleted from chromosome 10 (PTEN)-null glioblastoma cell, but it did decrease viability of U87-MG cells transfected with expression vectors for the sense PTEN, and this decrease was also prevented by cilostazol. Cilostazol as well as 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS-1619) and (3S)-(ϩ)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one (BMS 204352), maxi-K channel openers, prevented increased DNA fragmentation evoked by TNF-␣, which were antagonizable by iberiotoxin. TNF-␣-induced increased PTEN phosphorylation and decreased Akt/ cyclic AMP response element-binding protein (CREB) phosphorylation were significantly prevented by cilostazol, those of which were antagonized by both iberiotoxin and paxilline, maxi-K channel blockers. The same results were evident in U87-MG cells transfected with expression vectors for sense PTEN. Cilostazol increases the K ϩ current in SK-N-SH cells by activating maxi-K channels without affecting the ATP-sensitive K ϩ channel. Thus, our results for the first time provide evidence that cilostazol prevents TNF-␣-induced cell death by suppression of PTEN phosphorylation and activation of Akt/CREB phosphorylation via mediation of the maxi-K channel opening. Recent research has shown that the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is implicated in the regulation of several cellular functions, including cell viability from apoptosi

Synthesis and characterization of self-assembled nanoscopic metallarectangles capable of binding fullerenes with size-selective responses

Two new metallarectangles, 4 and 5, were obtained from the self-assembly of areneruthenium-based molecular clips 2 and 3 with a new dipyridyl donor ligand 1 containing a diamide core and ethynyl spacers. The metallarectangles were characterized by multinuclear NMR, electrospray ionization mass spectrometry, and UV-vis spectroscopy, and the molecular structure of 4 was unambiguously determined by single-crystal X-ray diffraction analysis. Because of the presence of an extended ??-electron aromatic surface, the tetracene-containing molecular rectangle 5 was capable of binding C60 and C70 fullerenes as quantified by UV-vis, emission, and 1H NMR experiments, providing an example of a supramolecular host capable of recognizing large guest molecules.close7

m-Iodosylbenzoic acid – a convenient recyclable reagent for highly efficient aromatic iodinations

m-Iodosylbenzoic acid performs iodinations of arenes in the presence of iodine at room temperature in acetonitrile. Separation of pure products is conveniently achieved by scavenging any aryl iodide by ion exchange with IRA-900 (hydroxide form). The reduced form of the reagent, m-iodobenzoic acid, can be easily recovered from the ion exchange resin or from the basic aqueous solution by simple acidification with HCl

Preparation of a chiral Pt-12 tetrahedral cage and its use in catalytic Michael addition reaction

The reaction of chiral cis-(1S,2S)-dch] Pt(NO3)(2) (M) where (1S,2S)-dch = (1S,2S)-1,2-diaminocyclohexane] with a hexadentate ligand (L) in 3 : 1 stoichiometric ratio yielded a 12+4] self-assembled chiral M12L4 molecular tetrahedron (T). The cage T features an internal 3D nanocavity with large open `windows', enabling it to catalyze Michael addition reactions of a series of nitrostyrene derivatives with indole in a 9 : 1 water : methanol mixture