Search results for "Ether"

Dual-stimuli pseudorotaxane switches under kinetic control

2021

A series of dumbbell-shaped sec-ammonium salts with bulky (pseudo)stoppers (‘speed bumps’) were tested for their ability to form pseudorotaxanes with a redox-switchable, tetrathiafulvalene (TTF)-decorated [24]crown-8 ether. Depending on the size of the pseudostoppers, fast (less than ten minutes), slow (hours to days) and very slow (no pseudorotaxanes observed) threading has been observed. NMR spectroscopy as well as tandem mass spectrometry indicate the formation of non-threaded face-to-face complexes prior to pseudorotaxanes formation. Both isomers can be distinguished by their substantially different stability in collision-induced dissociation (CID) experiments. Two external stimuli affe…

13C and17O NMR study of methoxy groups in chlorinated Di- and trimethoxybenzenes

1990

13C and 17O NMR data [chemical shifts and 1J(CH) values] for the methoxy groups in isomeric 1,2-, 1,3- and 1,4-dimethoxybenzenes, 1,2,3-trimethoxybenzenes and most of their chlorinated derivatives and some related brominated compounds were measured for CDCl3 solutions. The 17O NMR chemical shifts show up to 60 ppm dispersion. Comparison between the compounds with and without adjacent chlorine atoms (2,6-di- and 2,4,6-tri-substitution) also showed a clear methoxy carbon chemical shift change. The number and position of the chlorine atoms in the aromatic ring give small but observable effects on the 17O NMR chemical shifts of the methoxy group if it is coplanar with the aromatic plane. Simila…

Synthesis and chemico-physical characterization of tin(IV) complexes with some crown ethers

1986

Abstract Some neutral adducts of diorganotin(IV) perchlorates and thiocyanates with three crown-ethers have been synthesised; they are of the type Me 2 SnX 2 L m · n H 2 O where m = 1 or 2, n = 2 or 4, X = ClO 4 or NCS, and L = 18-crown-6, 15-crown-5, and 12-crown-4. The values for m and n have been correlated with the coordinating ability of the two anions and with the steric hindrance by the crown ether molecules. From infrared and Mossbauer data, an octahedral coordination geometry is proposed for all the complexes. The Mossbauer parameters are discussed in terms of the electronegativity of the ligands on the tin(IV) center and of the distortions produced in the coordination polyhedra by…

Emmy Noether. The mother of algebra

2011

Dall’alterità alla città. Regalità, sessualità e agricoltura in Gilgameš, Enkidu e gli Inferi

2021

Analisi antropologica del componimento mitologico sumerico Gilgamesh, Enkidu e gli Inferi

Dural splitting reconstruction in retethering after lipomeningocele repair: Technical note

2021

Background: Tethered spinal cord syndrome (TCS) can occur after the surgical repair of lipomeningoceles (LMCs). In these cases, the tethering results from postoperative adhesions between the spinal cord and the overlying repaired dura. A watertight dural closure using the residual dura and/or the surrounding tissues does not always provide enough space for the spinal cord and risks retethering. Here, we report a 16-year-old patient with secondary TCS following lipomeningocele repair who successfully underwent release of the tethered filum terminale utilizing a novel dural splitting reconstructive technique to attain a water-tight closure without the need for a duroplasty. Methods: A 16-yea…

Recent advances in green industrial networking [Guest Editorial]

2016

The articles in this special section focus on green industrial networking. Due to the explosive increase in energy usage, it is essential that governmental and industrial institutions address this problem. Therefore, the development of green and low-carbon economy has recently become a hot issue in the industry. It is envisioned in such cases to meet the growing demands for industrial networking with limited resources. This is considered one of the challenges that needs to be addressed. Addressing such key problems will hopefully allow us to reach the realization of sustainable development. We believe that network technologies will be critical and will greatly contribute to achieving large-…

Oligo(ether sulfones). 3. Block Copolymers via Condensation Reactions of Telechelic Oligo(ether sulfones) Bearing Phenolic Endgroups and Oligomeric α…

1999

Densities, Refractive Indices, and Excess Molar Volumes of Binary and Ternary Systems Containing Isobutyl Alcohol, Ethanol, 2-Methylpentane, and Meth…

2000

This paper reports experimental densities and refractive indices of binary and ternary systems containing isobutyl alcohol, ethanol, 2-methylpentane, and methyl tert-butyl ether over the whole composition range of mixtures at 298.15 K and atmospheric pressure. From these data, excess molar volumes VE have been calculated. These results are fitted to the Redlich−Kister and Cibulka polynomial equations to derive the binary and ternary coefficients, respectively.

Energetics of Water−Dodecyl Surfactant−Macrocyclic Compound Ternary Systems

1996

Enthalpies of dilution and osmotic coefficients of sodium dodecyl sulfate (NaDS) and dodecyltrimethylammonium bromide (DTAB) in water + 18-crown-6 ether (CR) and water + β-cyclodextrin (CD) at a fixed cosolvent concentration were measured at 298 and 310 K, respectively, as functions of the surfactant concentration (mS). Enthalpies of transfer ΔH (W → W + S) of CR (0.03 m) from water to NaDS and DTAB aqueous solutions as functions of mS were also determined at 298 K. From the enthalpies of dilution the apparent (LΦ,S) and partial (L2,S) molar relative enthalpies of both surfactants were calculated. Despite CR forms inclusion complexes with the anionic surfactant only, the L2,S vs mS profiles…