THE INTERACTION OF BIS[2-MERCAPTOETHANESULFONATO (2−)-Sl,BIS[L-CYSTEINATO(1−)-S], AND BIS[L-PENICILLAMINATO(1−)-Sl- DIMETHYLTIN (IV), WITH RAT HEMOGLOBIN: A119Sn MöSSBAUER SPECTROSCOPIC STUDY

Abstract

The title compounds, representative of classes of diorganotin (IV) derivatives active against murine leukemia P-388. interact with rat hemoglobin (selected as a model protein) by: i) co-crystallization. with formation of microcrystalline pellets, and: ii) diffusion into hemoglobin crystals from the supernatant solution (as determined for the 2-mercaptoethanesulfonato derivative). The nature of the Me₂Sn^IV species in hemoglobin has been investigated by ¹¹⁹Sn Mössbauer spectroscopy, and a C₂SnS₂ tetrahedral geometry has been assigned by the point-charge model rationalization of the nuclear quadrupole splitting parameter.

Binding into crystalline hemoglobin has been ascribed to Coulomb interactions and to hydrogen bonding between the sulfonate and the aminoacid tails of the organotin (IV) derivatives and functional groups of the globin.     

CHIRAL VARIANTS OF ARYLALKYL SULFUR REAGENTS. (R)-CAMPHOR KETIMINES OF OGIOVANNA AMINOTHIOETHERS AND OXIDES

Abstract

Ketimines la-d derived from ortho-aminosubstituted phenylthioethers were prepared in order to determine the degree of chirality transfer from the chiral auxiliary to the sulfur atom in the formation of the sulfoxide or to the α-carbon atom in the reaction of the anion with alkyl halides or benzaldehyde. Oxidation to the sulfoxide occurred with little or no asymmetric induction. The crystalline benzyl sulfone 4c was deprotonated by alkyllithium or Grignard reagents and reacted with alkyl halides and benzaldehyde, in all cases with little to fair transfer of chirality. The major diastereoisomer from methylation of the anion of 4c with methyl iodide, was isolated, and afforded the enantiomerically pure amine 5 after removal of the chiral auxiliary. An X-ray structure determination of 4d allowed the assignment of the absolute configuration of the asymmetric carbon and revealed that the conformation of the ketimine in the crystal state is not homogeneous.     

THE REACTION OF TERMINAL PHOSPHINIDENE COMPLEXES WITH ELECTRON-RICH ALKYNES: A NEW APPROACH TO THE PHOSPHOLE RING

Abstract

The reaction of electron-rich alkynes such as ethoxyacetylene or propynyldiethylamine with a transient terminal phosphinidene complex such as [PhP?W(CO)₅] directly yields the corresponding phosphole complexes via a formal [2 + 2 + I] cycloaddition involving two molecules of alkyne and one phosphorus center.     

Highly improved crystallization behavior of poly(L‐lactide) induced by a novel nucleating agent: substituted‐aryl phosphate salts

In this work, a novel nucleating agent (NA) based on substituted‐aryl phosphate salts was introduced into poly(L‐Lactide) (PLLA). The nonisothermal and isothermal crystallization behaviors of nucleated PLLA samples were investigated through differential scanning calorimetry (DSC), wide angle X‐ray diffraction, and polarized optical microscope (POM). Furthermore, the effect of annealing treatment on the cold crystallization behaviors of nucleated samples was also investigated. The results show that the crystallization of PLLA, whether for the melt crystallization (including nonisothermal and isothermal crystallization process) or for the cold crystallization (including the cold crystallization occurring during the DSC heating process and during the annealing process), is greatly dependent upon the content of NA. At relatively lower NA content (≤0.1 wt%), the nucleation effect of NA is inconspicuous, however, at higher NA content (≥0.2 wt%), it exhibits great nucleation effect for the crystallization of PLLA. Further results show that the double endothermic peak of PLLA depends on the temperature applied for the crystallization. Copyright © 2012 John Wiley & Sons, Ltd.     

Trends in Kinetic Behavior during Ester-Ester Exchange Reactions in Polyesters by Mass Spectrometry. I

The kinetics of the ester-ester exchange reaction between polyesters from adipic acid and various linear and branched glycols were investigated by mass spectometry using the dimer analysis method (DAM). Rate constants, activation energies, and frequency factors are given for reactions studied in the temperature range of 572–585 K. Correlation of glycol methylene ratios with activation energies and frequency factors shows an alternating trend in kinetic behavior. Reaction systems containing even numbers of methylene groups in the glycol moiety of the reactants exhibited slower reaction rates than systems with odd numbers of methylene groups, while branched reaction systems followed very similar trends when the influence of pendant groups is ignored.     

POLY(10-UNDECENOIC ACID) AND SOME OF ITS DERIVATIVES

Commercially available 10-undecenoic acid was esterified with 2,5-dimethylphenol. After the supply of ester was properly complexed, it was polymerized in quantities and in high yield to high molcular polymers. The polymeric esters were hydrolyzed with base to the acid salt, which were converted to the acids. Reactions with 1,1′-carbonyldiimidazole gave polyethylene-based polymeric imidazolids.     

Recent Advances of AIE-Active Conjugated Polymers: Synthesis and Application

Conjugated polymers (CPs) have long been recognized as an important class of materials. The highly conjugated backbone of the CPs will facilitate the rapid exciton migration and result in amplification of fluorescence signals. However, CPs are likely to aggregate and form excimers in solid states, directly leading to the fluorescence quenching, namely aggregation-caused quenching (ACQ), hence inhibiting their prospective utilizations in a large degree. Since the effect of aggregation-induced emission (AIE) is opposite to that of notorious ACQ, the AIE has raised great attention from scientists. CPs with AIE or aggregation-enhanced emission (AEE) features may help to solve the ACQ problem and meanwhile impart polymers with new properties and practical applications. In this review, we summarize the recent progress on the preparation of CPs with AIE or AEE characteristics, where AIE-active luminogens are located at polymer backbones or pendants. Their potential applications including fluorescent sensors, biological probes, and active layers for the fabrication of light-emitting diodes are also described.     

Electron Spin Resonance Study on Grafting of Tetrafluoroethylene onto Polyethylene

An ESR study has been made on the course of grafting of tetrafluoroethylene onto polyethylene. Alkyl and allyl radicals trapped in the polymers were measured under various grafting conditions. It was observed that alkyl radicals decay very rapidly when monomers are in contact with the irradiated polymer, while allyl radicals decay very slowly even in the presence of monomers as in the decay of radicals in irradiated polymers without monomers. The effect of pre-irradiation temperature on grafting was also studied, and the rate of grafting was found to be much faster for lower pre-irradiation temperatures. From these experimental results it was concluded that alkyl radicals play an important Tole in the initiation reaction of grafting.     

Anti‐static Agent Containing Zinc Oxide and its Modification for PA6 Fiber

A new anti‐static agent was synthesized from zinc oxide‐adipic acid‐polyethylene glycol and caprolactam by three‐step reactions. The antistatic agent (called poly(ether ester amide zinc oxide) or PEEAZ) was analyzed by IR and DSC. The results showed that zinc oxide existed in the main chain of PEEAZ. The glass temperature and melt temperature of poly(ether ester amide zinc oxide) (referred to as PEEAZ in the following) decreased with increasing poly(ether ester zinc oxide) increasing in PEEAZ. Antistatic PA6 fiber was obtained by adding PEEAZ 2–8% (wt/wt) to PA6 during blend spinning. The specific resistance and the static half‐value period of PA6 fiber was less than 10⁹Ω · cm and 60 sec, respectively. Excellent antistatic property remained after being washed 30 times.     

LIQUID CRYSTALLINE POLYMERS. IV. THERMOTROPIC LIQUID CRYSTALLINE POLY(ARYLIDENE-ETHER)S AND COPOLYMERS CONTAINING N-METHYLPIPERIDONE LINKED TO THE MAIN CHAIN THROUGH SPACERS OF VARIOUS LENGTHS

Two novel series of poly(arylidene-ether)s and copoly(arylidene-ether)s were synthesized from N-methylpiperidone and/or cyclohexanone respectively. The first series (homopolymers) was derived from 4,4′-diformyl-α,ω-diphenoxyalkane or 4,4′-diformyl-2,2′ dimethoxy-α,ω-diphenoxyalkane with N-methylpiperidone. The second series (copolymers) was derived from the diphenoxyalkanes (I–VIII) with N-methylpiperidone and cyclohexanone. The inherent viscosities of the polymers thus prepared were in the range of 0.37–0.98 dI/g. The majority of the polymers and copolymers are soluble in chlorinated hydrocarbons. DSC measurements and microscope observation under polarized light demonstrate that this type of poly(arylidene-ether)s form nematic mesophase over a wide temperature range in contrast to the corresponding copoly(arylidene-ether)s. All of the polymers and copolymers exhibited thermotropic liquid crystalline properties. In most cases, the mesophase extends up to 315°C, where thermal decomposition prevents further observation. The morphology of polymer IXb and copolymer XIb as a selected example was examined by scanning electronic microscope.