Remarkably efficient activation of glycosyl trichloro- and (N-phenyl)trifluoroacetimidates with bismuth(III) triflate

Easily handled and nontoxic Bi(OTf)₃ is a powerful activator for trichloro- and (N-phenyl)trifluoroacetimidate glycosyl donors. This catalyst allows glycosidations to be performed at low temperatures in very short times. Rewarding yields were obtained from a wide range of donors of varying reactivity.     

Engineering of CH3NH3PbI3 Perovskite Crystals by Alloying Large Organic Cations for Enhanced Thermal Stability and Transport Properties

The number of studies on organic–inorganic hybrid perovskites has soared in recent years. However, the majority of hybrid perovskites under investigation are based on a limited number of organic cations of suitable sizes, such as methylammonium and formamidinium. These small cations easily fit into the perovskite's three‐dimensional (3D) lead halide framework to produce semiconductors with excellent charge transport properties. Until now, larger cations, such as ethylammonium, have been found to form 2D crystals with lead halide. Here we show for the first time that ethylammonium can in fact be incorporated coordinately with methylammonium in the lattice of a 3D perovskite thanks to a balance of opposite lattice distortion strains. This inclusion results in higher crystal symmetry, improved material stability, and markedly enhanced charge carrier lifetime. This crystal engineering strategy of balancing opposite lattice distortion effects vastly increases the number of potential choices of organic cations for 3D perovskites, opening up new degrees of freedom to tailor their optoelectronic and environmental properties.     

Biodegradable Passion Fruit‐Like Nano‐Architectures as Carriers for Cisplatin Prodrug

Accumulation of inorganic nanostructures in the excretory system organs increases their likelihood of toxicity and interference with common medical diagnoses. Thus, one of the major concerns regarding their clinical translation is related to their persistence in organisms. Here the authors demonstrate that nano‐architectures composed by hollow silica nanocapsules embedding arrays of ultrasmall gold nanoparticles undergo biodegradation in cellular environment affording small, potentially clearable building blocks. Furthermore, the authors present their exploitation in glutathione‐triggered release of covalently loaded cisplatin prodrug. This endogenously triggered release leads to high cytotoxicity to human pancreatic carcinoma cells, setting the way for promising applications to synergistic dual chemo/radio‐therapy and radio‐imaging.     

Synthesis and structure of some azo coupled cyclic beta-enaminones

The reaction of 3-phenylaminocyclopent-2-en-1-one with 4-methyl, 4-methoxy and 4-chlorobenzenediazonium tetrafluoroborates was used to prepare the azo coupling products 3a-c. It was found that these compounds are present in both CDCl(3) solution and solid phase practically exclusively as (E)-3-phenylamino-2-(4-subst.phenyldiazenyl)cyclopent-2-en-1-ones with N--H...N intramolecular hydrogen bond. The substitution of the phenyl residue of the diazonium salt has no effect on the position of the tautomeric equilibrium. On the other hand, the compounds 4a, b formed by the reaction of 3-phenylamino-1H-inden-1-one with 4-methylbenzene- or benzenediazonium tetrafluoroborates exist in CDCl(3) solution and in solid phase as hydrazone compounds. In the solution they occur as a mixture of three forms, out of which two were identified as E/Z isomers with different types of hydrogen bonds. Compound 5 formed by the reaction of 3-amino-5,5-dimethylcyclohex-2-en-1-one with 4-methoxybenzenediazonium tetrafluoroborate is converted into a stable hydrochloride 5.HCl on standing in CHCl(3) solution; this product exhibits a high degree of delocalization of the positive charge. Its structure was studied by means of X-ray.     

Synthesis, characterization and reactivity of new complexes of titanium and zirconium containing a potential tridentate amidinato-cyclopentadienyl ligand

Group 4 metal complexes [M(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, pyrazine, pyrimidine, thiazole, M = Ti; R = pyridine, thiazole; M = Zr) containing the tetramethylcyclopentadienyl-dialkylsilyl bridged amidinato as pendant ligand, were synthesized and characterized by elemental analysis, solution (1)H, (13)C and (15)N NMR spectroscopy and experimental (13)C and (15)N CPMAS in the solid state. The crystal structures of [Ti(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, pyrazine, pyrimidine, thiazole) were determined by single crystal X-ray diffraction studies. All compounds exhibit a distorted tetrahedral geometry, with the ansa-monocyclopentadienyl-amido ligands acting in a bidentate mode. The [M(eta(5)-C(5)Me(4)SiMe(2)-eta(1)-N-2R)(NMe(2))(2)] (R = pyridine, thiazole; M = Zr, Ti) complexes are ethylene polymerization catalysts in the presence of MAO and they are active precursors in regioselective catalytic hydroamination operating with an anti-Markovnikov mechanism.     

Evaluation of 2-methyl-3-hydroxy-4-pyridinecarboxylic acid as a possible chelating agent for iron and aluminium

In view of a possible application to Fe and Al chelation therapy, 2-methyl-3-hydroxy-4-pyridinecarboxylic acid (DT2) was synthesised, and its complex formation, electrochemical and cytotoxic properties were studied. The complexing properties of DT2 towards Fe(III) and Al(III) were investigated in aqueous 0.6 m (Na)Cl at 25 degrees C by means of potentiometric titrations, UV-vis spectrophotometry, and 1H NMR spectroscopy. DT2 is a triprotic acid (H3L+) having pKa1 = 0.47, pKa2 = 5.64 and pKa3 = 11.18. The metal-ligand complexes observed in solution and their corresponding stability constants (log beta values) are the following: FeLH (19.38), FeL (16.01), FeLH(-1) (12.28), FeL2H2 (37.29), FeL3H3 (53.41), FeL3H2 (47.99), FeL3H (41.21) and FeL3 (34.1); AlLH (17.43), AlL2H2 (33.74), AlL2H (27.6), AlL3H3 (48.72), AlL3H2 (42.67), AlL3H (35.8) and AlL3 (27.92). The complex formation between DT2 and Fe(II) was studied by UV-vis: the weak complex FeLH (log beta = 15.8) was detected. DT2 shows a lower complexation efficiency with Fe(III) and Al(III) than that of other available chelators, but higher than that of its non-methylated analogue 3-hydroxy-4-pyridinecarboxylic acid (DT0). The electrochemical behaviour of DT2 was investigated by means of cyclic voltammetry, indicating that the oxidation of the ligand proceeds through a two electron process with a CECE mechanism. Voltammetric curves suggest that the oxidation or the reduction of DT2 in vivo is unlikely. According to the thermodynamic data, also the Fe(III)-DT2 complexes do not undergo redox cycling at physiological pH. Amperometric titrations of solutions containing Fe(III) and DT2 at pH = 5 indicated the same Fe(III) : ligand stoichiometric ratio as calculated from potentiometric data. The toxicity of DT2 and of other simple hydroxypyridinecarboxylic acids was investigated in vitro and no cytotoxic activity was observed (IC50 > 0.1 mM) on cancer cell lines and also on primary human cells, following a three day exposure.     

Experimental falsification of Leggett's nonlocal variable model

Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also, some models based on nonlocal variables, if subject to apparently "reasonable" constraints, may fail to reproduce quantum physics. In this Letter, we introduce a family of inequalities, which use a finite number of measurement settings, and which therefore allow testing Leggett's nonlocal model versus quantum physics. Our experimental data falsify Leggett's model and are in agreement with quantum predictions.     

A ketone oximate based cyclic cationic [Ni(II)4] inverse metallacrown from simultaneous chelation and bridging of two ligands

The Ni(4) inverse metallacrown (NHEt(3)) [Ni(4)(bmo)4(Hael)2(ael)2](ClO(4))3 [(NHEt(3)).1.(ClO(4))3], with the inverse 12-MC-4 motif, has been assembled via simultaneous chelation and bridging of butan-2,3-dionemonoxime (Hbmo) and 2-amino ethanol (Hael).