Synthesis and characteristics of novel chelate fiber containing amine and amidine groups

A polyacrylonitrile (PAN) fiber was adopted for the backbone of a chelate polymer and poly(acrylo‐amidino ethylene amine) (PAEA) was prepared through a one‐step reaction between the PAN fiber and ethylenediamine (EDA). The maximum removal capacity and degree of substitution were 7.8 meq per gram of dried PAEA and 98%, respectively. The PAEA was tested as an adsorbent in single and two‐component metal aqueous solutions under changing pH. The Cu²⁺ ion accomplished maximum adsorption amount at pH 3 and the order of maximum adsorbed amounts on PAEA is Cu²⁺ > Ag⁺ > Zn²⁺ > Ni²⁺ > Pb²⁺ in molar basis. FT‐IR spectroscopy was employed to characterize the chemical bonding in metal aqueous solutions and surface morphology was examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis of a conformationally locked version of puromycin amino nucleoside

[reaction: see text] A conformationally locked carbocyclic version of puromycin amino nucleoside was synthesized via Mitsunobu coupling of a 3-azido-substituted carbocyclic moiety with 6-chloropurine without interference from the azido group reacting with triphenylphosphine. The requisite 3-azido-substituted carbocyclic pseudosugar was prepared by a double inversion of configuration at C3' (nucleoside numbering) involving a nucleophilic displacement with azide.     

Synthesis and properties of polyketones containing thiophene links

A series of polyketones containing thiophene links was synthesized by the Friedel-Crafts polymerization of these dithienylalkanes with aromatic diacid chlorides or dicarbonyl chlorides comprising thiophene links with diphenyl compounds. The resulting polymers had inherent viscosities in the range of 0.11–0.27 dL/g and showed poor solubilities to common organic solvents except strong acids. These thiophene-based polyketones exhibited fairly good thermal stabilities. The TGA data revealed 5% weight losses at 375–450°C and residual weights at 500°C were 43–79% under nitorgen. It was found that the thermal stabilities of these polymers were superior to those of polymides or polysulfonamides containing thiophene links and almost comparable to common aromatic polyketones     

Spectrofluorimetric determination of copper(II) by its static quenching effect on the fluorescence of 4,5-dihydroxy-1,3-benzenedisulfonic acid

A spectrofluorimetric method has been developed for the determination of trace Cu(II) in real samples with 4,5-dihydroxy-l,3-benzenedisulfonic acid (Tiron) as a fluorimetric reporter. Tiron is very soluble in water and is a good fluorimetric reagent. However, as Tiron was complexed with Cu(II), the fluorescence intensity decreased proportionally to the concentration of Cu(II) by a static quenching effect. The excitation wavelength and the fluorescence wavelength of Tiron were 294 and 350 nm, respectively, as it was caused by a quenching effect from Cu(II) at pH 8.0. The highest sensitivity was shown at Tiron concentration of 5.0x10(-5) M. To enhance the quenching effect, the Cu(II)-Tiron complex solution was heated up to 80 degrees C for 90 min. As for Cu(II), the interference by Co(II) was very serious, which was eliminated by oxalate ion. The linear response to Cu(II) was shown at the concentration range between 5.0x10(-7) and 1.0x10(-5) M. With this proposed method, the detection limit of Cu(II) was 3.83(+/-0.09)x10(-7) M. Recoveries of Cu(II) in the diluted brass samples and the stream water samples were almost 100%. Based on results from the experiment, this proposed technique could be applied to the practical determination of Cu(II) in real samples.