Sequential Formation of Heteroternary Cucurbit[10]uril (CB[10]) Complexes

The globular and monocationic guest molecule trimethyl-azaphosphatrane ( AZAP , a protonated Verkade superbase) was shown to form a host:guest 1 : 1 complex with the cucurbit[10]uril (CB[10]) macrocycle in water. Molecular dynamics calculations showed that CB[10] adopts an 8-shape with AZAP occupying the majority of the internal space, CB[10] contracting around AZAP and leaving a significant part of the cavity unoccupied. This residual space was used to co-include planar and monocationic co-guest ( CG ) molecules, affording heteroternary CB[10]⋅ AZAP ⋅ CG complexes potentially opening new perspectives in supramolecular chemistry.     

Iron(II)/copper(I)-mediated stereoselective carbozincation of ynamides. One-pot synthesis of α-allyl-tetrasubstituted-enamides

The iron(II) chloride- and copper(I) iodide-mediated carbozincation of a panel of substituted ynamides is described in this article. The reaction is totally regio- and stereoselective. Experiments showed that the reaction mediated with Fe(II) was more substrate dependent than the reaction performed with Cu(I). Interestingly, in the presence of allylbromide, stereoselective carboallylation can be achieved for the first time in a one-pot procedure, leading to skipped dienamides.     

1,3‐Alternate Tetraamido‐Azacalix[4]arenes as Selective Anion Receptors

Six tetraaza[1.1.1.1]cyclophane derivatives bearing peripheral amide groups were prepared according to two distinct synthetic strategies that depend on the connection pattern between the aryl units. NMR experiments combined with the X‐ray structures of two tetraamide derivatives 4 b and 10 show that these cavitands adopt a 1,3‐alternate conformation both in solution and in the solid state. Consequently, the four amide groups of the aza[1.1.1.1]‐m,m,m,m‐cyclophane isomer 10 can contribute to the same recognition process towards neutral water molecules or anion guests. NMR experiments, mass spectrometry analyses and single‐crystal X‐ray structures confirm the anion‐binding ability of this receptor. Absorption spectrophotometric titrations in nonpolar solvents provided evidence for the selectivity of 10 to chloride anions in the halide series, with a corresponding association constant K_a reaching 2.5×10⁶ m ^?1.     

A Convenient one Pot Synthesls of Oxadiazoles

4,5-Diaryl-3-.styryl-4,5-dihydro[l,2,4] oxadiazoles have been synthesized through a faoile, 1,3-dipolar oyclo-addition of azomethines and phenylaorylonitrile oxide generated in situ, in a single step process.     

EPR and optical absorption studies of X-irradiated cobalt doped sodium chloride crystals

Sodium chloride crystals containing small concentrations of cobalt (< 10 ppm) do not show any EPR line. A thick block of crystal containing ～25 ppm of Co showed two partially resolved lines, with approximate g-values 2.036 and 2.011. These g-values are not close to those of Co⁺⁺ (4.0 to 4.5) in other crystals. On X-irradiation, pure NaCl crystals show a complex EPR spectrum. X-irradiated Co doped NaCl crystals showed an EPR line superimposed on the complex EPR spectrum. Cobalt doped highly pure crystals, on X-irradiation, showed an EPR line superimposed on the F center EPR line. The g-value of the former is 2.049±0.002 and half width is 62±3 gauss. These results combined with those of dielectric loss and optical studies show that X-irradiation of Co doped crystals produces new centers, labelled as S centers, which produce a dielectric loss peak, a decrease in electrical conductivity, an optical band at 210 nm and the EPR line. Possible models of the S centers are discussed.     

Reflection and transmission of electromagnetic waves from a nonlinear anisotropic slab between two linear isotropic media

Summary In this paper, the author has studied the reflection from and transmission through a homogenous nonlinear anisotropic slab (anisotropy being due to an external magnetic field) bounded by two linear isotropic media. Nonlinear equations describing the growth of the two modes of propagation of an electromagnetic wave in the direction of the magnetic field, in an anisotropic nonlinear medium, have been set up and solved; the solutions have been used to obtain expressions for the reflected and transmitted components of the incident wave. The simpler problem of the reflection and transmission from an isotropic nonlinear slab has also been discussed as a special case.     

Facile synthesis,characterization, and antimicrobial studies of some disubstituted 1,2,3-triazoles with sulfonamide functionality

An expedient synthesis of some 1,4-disubstituted 1,2,3-triazoles (3a–3x) having sulfonamide functionality from various terminal alkynes and aromatic azides through Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition has been reported. The structures of newly synthesized compounds were confirmed by IR, ¹H NMR, ¹³C NMR, high-resolution mass spectra and screened for in vitro antimicrobial activity against Staphylococcus aureus (Gram-positive bacteria), Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes (Gram-negative bacteria), Candida albicans, and Aspergillus niger (fungi). Some of the synthesized compounds were found to exhibit good potency against above-tested microbial strains. Moreover, to study the binding interactions, docking simulation of broadly active compound 3x was also performed against E. coli dihydropteroate synthase enzyme.