Synthesis and Characterization of New Schiff Base and Polyoxa-azaCryptands and Their Rare Earth Cryptates with [1 1] Condensation and Reduction Methods

IntroductionWithspecialandnovelstructures,macropolycyclicmoleculespreselltamultitudeofnewproperties'andopenupvastvistasforapplicationsinmanyfields"',suchassupramoleculardevices,luminescentlabels,fluorescentprobesinbiologicalandmedicalapplications,magneticresonanceimagingandcatalyticcleavageofRNA,and.-theyarealsoimportantligands'forrecognizinginorganicandorganiccanons,anionsandneutralmolecules.Becauseofmulti-stepprocessandlowyields',thesynthesisofmacropolycycliccompoundsaresometimesverydifficu…     

X-ray structure and thermal analysis of a 1∶1 complex between sulfathiazole andβ-cyclodextrin

An inclusion complex with the formula (-cyclodextrin) (sulfathiazole) 8.3 H₂O has been crystallized and characterized by physicochemical methods including single crystal X-ray analysis. The complex crystallizes in the monoclinic system, space group P2₁, witha=15.264(4),b= 16.500(6),c=15.559(5) Å,=117.29(3)^o andZ=2. The structure was solved using published co-ordinates for-cyclodextrin in an isomorphous complex. Refinement by block-diagonal leastsquares yieldedR=0.061 for 4706 unique observed reflections. Inclusion of sulfathiazole produces a slight ellipticity in the host conformation, but the guest adopts a conformation similar to that observed in its polymorphs. The guest is held in the macrocyclic cavity predominantly by hydrophobic forces, with the phenyl ring near the host primary hydroxyl side and the thiazole ring near the secondary hydroxyl side. The complex packs in layers parallel to theac-plane. Layers are linked by hydrogen bonding to water molecules which are located outside the cyclodextrin cavity. An extensive network of hydrogen bonds mediated chiefly by water molecules stabilizes the crystal structure.     

Synthesis and optical limiting in copolymers of C_(60) and 1-phenyl-1-butyne

Since the discovery of the methods for mass production of fullerenes', there has beengreat interest in the development of fullerene-containing polymeric materials'-' becausesuitably designed fullerene polymers not only possess good processability but also exhibitinteresting materials properties'-'. We have also attached C,o to polyphenylacetylenechains by a WCI,~catalyzed copolymerization reaction'-'. In this letter, we chose anacetylene monomer, that is, l-phenyl-butyne (PB), which can not …     

Synthesis of sulfonimide-based dendrimers and dendrons possessing mixed 1 → 2 and 1 → 4 branching motifs

The synthesis of dendrimers and a chlorosulfo-dendron possessing a unique combination of 1?→?2 and 1?→?4 branching types is described. The procedure consists of a two-step preparation of 3,5-dinitrobenzene-1-sulfonyl chloride, which was used for the persulfonylation of p-toluidine and 4-(benzylthio)aniline. The obtained tetranitro compounds were reduced to the corresponding tetraamines. The latter were decorated with eight 4-toluene sulfonyl groups each to furnish the corresponding dendrimers. Oxidation of the dendrimer possessing a 4-(benzylthio)phenylene core with N-chlorosuccinimide resulted in the formation of a dendron with a sulfonyl chloride functionality at the focal point.     

Synthesis and Crystal Structure of 2-Amino-1, 1-diferrocenylethanol

2-Aminoalcohols are useful intermediates in organic chemistry, for example, they serve for the synthesis of various heterocycles1, chelate complexes2, and for the ring expansion of cycloalkanones3. 2-Aminoalcohols containing ferrocene as bidentate ligand may be converted into multinuclear compounds. Several methods for the preparation of 2-aminoalcohols have been developed including reduction of the trimethylsilyl cyanohydrins4 or β-nitromethyl alcohols5 and treatment of the epoxides with a…     

1′-Azido- and 1′-amino-1,3-dioxolan-4-ones

1,3-Dioxolanone alcohols, prepared via the addition of chiral lithium enolates of 1,3-dioxolan-4-ones to aldehydes, are suitable intermediates for the synthesis of chiral trisubstituted isoserines or trisubstituted 3-hydroxy-β-lactams. In particular, the methyl ester of 2-methyl-3-(2-furyl)isoserinic acid and two 3-methyl-3-hydroxy-β-lactams bearing either a 2-furyl or a phenyl substituent at C-(4) have been prepared. The (2R,3S) stereochemistry of the isoserine, and the (3R,4S) stereochemistry of the two β-lactams is that required for the synthesis of taxoid analogues having the side-chain with the proper (2′R,3′S) configuration.     

Synthesis and Catalytic Application of Chiral 1, 1-Binaphthyl Polymers

Polymer-supported reagents and catalysts have attracted considerable attention as they offer alternative methods to separate and reuse expensive and often toxic chemicals1. Traditionally, the polymer-supported chiral catalysts are prepared by anchoring highly enantioselective monomeric catalysts to flexible and sterically irregular polymer supports. Because of the stereo-irregularity and flexibility of the traditional polymeric chiral catalysts, their catalytic sites do not have well-defined…     

X-ray Structure and Thermal Properties of a 1:1 Inclusion Complex Between Permethylated β-Cyclodextrin and Psoralen

The phytoalexin psoralen (7H-furo[3,2-g][1]benzopyran-7-one) has been included in heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB) to yield a solid crystalline complex of formula TRIMEB-psoralen-H₂O. Its X-ray structural elucidation provides an accurate model for cyclodextrin–furocoumarin interaction. Thermal analysis (hot stage microscopy, differential scanning calorimetry, thermogravimetry) indicated complex dehydration in the range 40–100°C followed by melting at 137.1°C. The X-ray analysis showed that the elongated guest molecule induces elliptical distortion in the host molecule, with which it interacts via C-H ?O hydrogen bonding and hydrophobic interactions. The host molecule adopts a very similar conformation to that in the isostructural complex with l-menthol as guest. Water molecules bridge symmetry-related TRIMEB molecules by hydrogen bonding.     

Synthesis and Crystal Structure of a 1-D Copper（Ⅱ） Polymer with 1-Hexylimidazole and Oxalate

A novel Cu（Ⅱ） complex has been prepared by means of self-assembly of CuCl2, 1-hexylimidazole L and oxalic acid （H2OX） in the presence of triethylamine, and structurally characterized by X-ray diffraction analysis. In complex 1, 1-D polymer chains are formed through pentacoordinated Cu（Ⅱ）, oxalate and bridging chlorine atoms. In the crystal packing of 1, the imidazole ring head-to-tail π-πstacking interactions exist between 1-D polymer chains and extend the 1-D polymer chains into 2-D supramolecular layers. The fluorescence emission spectra of L and 1 were described.     

Synthesis of α-activated Δ1 pyrroline and Δ1 piperideine: 1,3 dipolar and anionic reactivities.

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Thermodynamic and acoustic properties of binary mixtures of PEGDME 250 with 1-propanol and 1-butanol at 293, 303 and 313°K

ABSTRACT

The work presented in this paper deals with the study of thermodynamic properties of new working fluids for absorption machines, mainly for characterisation of absorbent–refrigerant pairs that could improve the cycle performance. The study of atomic motion in liquids plays an important role in understanding the solid-like behaviour of liquids. The accurate measurement of the energy changes due to scattering can be used to study the dynamical behaviour of liquids. Measurements of the ultrasonic velocity (u), density (ρ) and viscosity (η) for binary mixtures of polyethylene glycol 250 dimethyl ether with 1-propanol and 1-butanol have been made at three temperatures (T = 293, 303 and 313 K) over the entire composition range in order to investigate the nature of intermolecular interactions between the components of these liquid mixtures. Non-linear variation of derived quantities with the mole fraction supports the molecular interaction occurring between component molecules.     

Laser ionization spectra and electronic structure of Kn and NaKn−1 clusters

Photoionization of small K_n and NaK_n−1 clusters with n ⩽ 34 has been achieved in a crossed laser-molecular-beam experiment. The relative ion peak intensities in mass spectra reveal fragmentation effects which are wavelength-dependent. The vertical ionization profiles in the threshold region give some insight into the electronic structure.     

H atom adsorption and diffusion on Si(110)-(1×1) and (2×1) surfaces

We present a periodic density-functional study of hydrogen adsorption and diffusion on the Si(110)-(1×1) and (2×1) surfaces, and identify a local reconstruction that stabilizes the clean Si(110)-(1×1) by 0.51 eV. Hydrogen saturates the dangling bonds of surface Si atoms on both reconstructions and the different structures can be identified from their simulated scanning tunneling microscopy/current image tunneling spectroscopy (STM/CITS) images. Hydrogen diffusion on both reconstructions will proceed preferentially along zigzag rows, in between two adjacent rows. The mobility of the hydrogen atom is higher on the (2×1) reconstruction. Diffusion of a hydrogen vacancy on a monohydride Si(110) surface will proceed along one zigzag row and is slightly more difficult (0.2 eV and 0.6 eV on (1×1) and (2×1), respectively) than hydrogen atom diffusion on the clean surface.     

Association-Assisted Kinetics of Pentanol-1 and Heptanol-1 Oxyethylation: Kinetic Parameters of Reactions and Association Parameters of Alcohols in the Series Butanol-1–Heptanol-1

The kinetics of pentanol-1 and heptanol-1 oxyethylation in the absence and in the presence of solvents (dodecane, p-xylene, and 1,4-dioxane) is studied under the conditions of base catalysis at 80–150°C and the concentrations of the catalyst (the corresponding sodium alkoxide) and ethylene oxide in the starting mixture of 1 and 10^–3–10^–1 mol/l, respectively. The experimental results are adequately described by the rate law that takes into account the association of alcohol molecules via hydrogen bonds. A hypothesis is advanced that an associate consisting of n alcohol molecules acts as a kinetically independent species in this reaction. The kinetic and association parameters for alcohols in the C₄–C₇ series are compared with the published data.     

Excess Molar Volumes for Binary Mixtures of 1-Alkanol and 1-Alkene. II. The System 1-Alkanol + 1-Octene at 15 and 35°C

Excess molar volumes V ^E measured at 15 and 35°C for the (1-propanol + 1-octene), (1-butanol + 1-octene), (1-octanol + 1-octene), and (1-decanol + 1-decene) systems are reported. These data and the measurements reported before at 25°C for this series of mixtures were used to calculate the excess molar isobaric thermal expansion A _p ^E = ( V ^E/ T)_p at 25°C. In the above series of mixtures the A _p ^E values change from positive over the whole concentration range in the systems formed by 1-propanol and 1-butanol, to positive-negative for longer chain alkanols, the positive values occurring in the alkene-rich region. For systems characterized by the sigmoid shape, the positive region of A _p ^E values decreases with increasing length of the 1-alkanol molecule. The modified model of associated mixtures proposed by Treszczanowicz and Benson predicts qualitatively the changes in the shape of the A _p ^E curves. The model allows interpretation of the above results as a balance between the contributions due to self-association of alkanol, nonspecific interactions, and free volume.     

Synthesis of substituted dihydro-1H-pyrazoles and 1H-pyrazoles via formal [4+1] annulation of α-arylhydrazonoketones and dimethyl sulfonium methylides

A formal [4+1] annulation of readily available α-arylhydrazonoketones and dimethyl sulfonium methylides is described, which involving tandem ylide-mediated addition and nucleophilic cyclization reactions. This transformation features mild reaction conditions, simple execution, good to high yields, and provides straightforward synthesis of substituted dihydro-1H-pyrazoles and 1H-pyrazoles via C-C and C-N bond formation.     

Preparation and properties of the systems Co1−xRhxS2, Co1−xRuxS2, and Rh1−xRuxS2

Members of the systems Co_1−xRh_xS₂ (0 ≤ x ≤ 0.6) were prepared, and their crystallographic and magnetic properties studied. The observed ferromagnetic moments for compositions where x ≤ 0.2 indicate a ferromagnetic alignment between Co(3d⁷) and Rh(4d⁷) electrons. This is the first observation of localized behavior of 4d electrons in the pyrite structure. Members of the systems Co_1−xRu_xS₂ (0 ≤ x ≤ 1) and Rh_1−xRu_xS₂ (0.5 ≤ x ≤ 1) were also prepared and their crystallographic and magnetic properties studied. From comparison with the Co_1−xRh_xS₂ system, it appears that the 4d electrons of Rh(4d⁷) are localized in the presence of Co(3d⁷) but are delocalized in the presence of Ru(4d⁶). The magnetic susceptibility of the Co_1−xRu_xS₂ system is sensitive to the homogeneity of the products and indicates that Ru(4d⁶) behaves as a diamagnetic ion.     

Syntheses and Bioactivity of 4＂-Sulfonate-5-triphenyl silyl Avermectin B1a and Ivermectin B1a Derivatives

Fourteen new derivatives of avermectin B1a, and ivermectin B1a were synthesized from C5-O-triphenyl silylavermectin B1a and ivermectin B1a (yield from 40% to 83%). Their chemical structures were characterized by means of IR. ^1H NMR, ^13C NMR and FAB-MS spectrometries. Some of them show excellent insecticidal activity.