Regio- and stereoselective lithiation and electrophilic substitution reactions of N-Alkyl-2,3-diphenylaziridines: solvent effect

[structure: see text]. The lithiation reaction of cis- and trans-N-alkyl-2,3-diphenylaziridines has been investigated. While cis-diphenylaziridines do not undergo any lithiation upon treatment with organolithiums, the lithiation reaction of the trans counterparts is completely alpha-regioselective and the stereochemical course of the lithiation-trapping sequence is solvent dependent: inversion of configuration in coordinating solvents (THF or toluene/crown ether) and retention in hexane, ether, or toluene. The preparation of stereodefined functionalized N-alkyl-2,3-diphenylaziridines is described.     

Investigation into the reactivity of the coordinatively unsaturated phosphonodithioato [Ni(MeOpdt)2] towards 2,4,6-tris(2-pyridyl)-1,3,5-triazine: goals and achievements

The reaction between the coordinatively unsaturated phosphonodithioato complex [Ni(MeOpdt)2] (1) [MeOpdt = (MeO)(4-MeOC(6)H(4))PS2-] and tptz [2,4,6-tris(2-pyridyl)-1,3,5-triazine] has been investigated. Spectrophotometric and conductometric titrations showed the formation of a neutral and an ionic species, i.e. [Ni(MeOdtp)2(tptz)] (2) and [Ni(tptz)2](MeOdtp)2 (3), in correspondence to 1 : 1 and 2 : 1 tptz : ratios, respectively. XRD studies confirmed the formation of both complexes isolated in the compounds 2.MeOH and 3.4H(2)O. In the neutral complex 2 the central Ni(II) ion features a distorted octahedral coordination, achieved through three N-atoms of tptz and three S-atoms belonging to two MeOpdt anions, one of which unexpectedly acts as a monodentate S-donor. In 3.4H(2)O, the two phosphonodithioato anions are non-coordinating and counterbalance the charge of the [Ni(tptz)2](2+) distorted octahedral complex. From the reaction 2 of with I2 and Br2, crystals of [Ni(tptz)2](I3)2 (5) and [Ni(tptz)Br(micro-Br)]2 (6) have been obtained. The dinuclear complex 6 features a structure showing tubular canals with openings of about 6 x 6 A.     

Synthesis and characterization of positively capped CdTe quantum wires that exhibit strong luminescence in aqueous media

The novelty of the current work lies in the versatile synthesis of highly luminescent water-soluble CdTe quantum rods (QR) which to the best of our knowledge are the first known water-soluble QR carrying positively charged stabilizer.     

Template Assembly of Polyiodide Networks at Complexed Metal Cations: Synthesis and Structures of [Pd2Cl2([18]aneN2S4)]1.5I5(I3)2 and [K([15]aneO5)2]I9

The cations [Pd ₂ Cl ₂ L] ²⁺ and [KL ₂ ^{′ +} (L = [18]aneN₂S₄, L′ =[15]aneO₅) have been used as templates for the synthesis of unique three-dimensional polyiodide networks. The metal cations in [Pd₂Cl₂L]_1.5I₅(I₃)₂ are linked into infinite chains by pairwise hydrogen bonding; the resulting cationic polymers run through channels formed by the extended polyiodide network. [KL₂^′]I₉ shows a three-dimensional network of puckered cubic cages of I₉⁻ ions whose cavities are occupied by the metal cations (section from the structure shown on the right).     

Bond-based peridynamic modelling of singular and nonsingular crack-tip fields

A static meshfree implementation of the bond-based peridynamics formulation for linearly elastic solids is applied to the study of the transition from local to nonlocal behavior of the stress and displacement fields in the vicinity of a crack front and other sources of stress concentration. The long-range nature of the interactions between material points that is intrinsic to and can be modulated within peridynamics enables the smooth transition from the square-root singular stress fields predicted by the classical (local) linear theory of elasticity, to the nonsingular fields associated with nonlocal theories. The accuracy of the peridynamics scheme and the transition from local to nonlocal behavior, which are dictated by the lattice spacing and micromodulus function, are assessed by performing an analysis of the boundary layer that surrounds the front of a two dimensional crack subjected to mode-I loading and of a cracked plate subjected to far-field tension.     

Intramolecular cyclization of 4,7‐bis(2‐bromo­acetyl)‐1‐thia‐4,7‐di­azacyclo­nonane

The reaction of 1‐thia‐4,7‐di­azacyclo­nonane with bromo­acetyl bromide in CHCl₃ affords the unexpected salt 4‐(2‐bromo­acetyl)‐8‐oxo‐1‐thionia‐4,7‐di­aza­bi­cyclo­[5.2.2]­un­decane bromide, C₁₀H₁₆BrN₂O₂S⁺·Br⁻. Two units of the salt are linked by S⋯Br contacts about a crystallographic inversion centre, thus forming dimers that are linked by Br⋯Br contacts into extended ribbons. S⋯O contacts between these ribbons generate a two‐dimensional sheet.     

An easy access to unsymmetrically substituted 4,4′-bi-1,2,3-triazoles

A convenient synthesis of 4-alkynyl-1,2,3-triazoles and novel unsymmetrically substituted 4,4′-bi-1,2,3-triazole derivatives has been devised starting from easily available 1-trimethylsilyl-1,3-butadiyne. The starting compound was reacted with several azides, leading to 4-(silylalkynyl)-1,2,3-triazoles, which were easily transformed into 4-arylalkynyl-1,2,3-triazoles by a Pd catalyzed coupling reaction with aryl halides, or into novel 4,4′-bi-1,2,3-triazole derivatives by a subsequent cyclization reaction with azides.     

Identification of genotoxic compounds in the airborne particulate matter endowed by small aerodynamic diameter in the city of Catania (Italy)

Airborne particulate matter (PM) is one of the most important polluting factors in the atmosphere containing solid particles generated during the combustion processes. PM, due to the particle size, is easily inhaled and constitutes a potential hazard for the human health. We previously documented, using in vitro cell culture systems, cytogenetic damages caused by exposure to a non-fractionated PM in two different areas from the city of Catania (Sicily, Italy). In the present work, the PM was fractionated in six different sub-fractions, and the relative extractable organic matters (EOM) were analyzed in order to quantify the presence of Polycyclic Aromatic Hydrocarbons (PHAs), a well known class of genotoxic agents. More than 70% of the total EOM was found in the PM with aerodynamic diameters less than 3.5 microm (PM35), and about 60% of the total EOM was detected between PM0.14 and PM1.2. Also the large amount of all the analyzed PAHs were found between the PM0.14 and PM1.2. The obtained data indicates that the genotoxic effect previously shown on mammalian cells (Chinese hamster epithelial liver cells) should be due, in the large part, to the PM with smaller particle size, namely less than PM1.2.     

Synthesis of 1,3-dihydrobenzo[c]furans from ortho-lithiated aryloxiranes

A general method for the synthesis of hydroxyalkyl 1,3-dihydrobenzo[c]furans from ortho-lithiated aryloxiranes and carbonyl compounds is described.