New fluorous ponytailed 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium halide salts

It is possible that fluorous compounds could be utilized as directing forces in crystal engineering for applications in materials chemistry or catalysis. Although numerous fluorous compounds have been used for various applications, their structures in the solid state remains a lively matter for debate. The reaction of 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridine with HX (X = I or Cl) yielded new fluorous ponytailed pyridinium halide salts, namely 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium iodide, C₈H₉F₃NO⁺·I⁻, (1), and 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium chloride, C₈H₉F₃NO⁺·Cl⁻, (2), which were characterized by IR spectroscopy, multinuclei (¹H, ¹³C and ¹⁹F) NMR spectroscopy and single‐crystal X‐ray diffraction. Structure analysis showed that there are two types of hydrogen bonds, namely N—H…X and C—H…X. The iodide anion in salt (1) is hydrogen bonded to three 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations in the crystal packing, while the chloride ion in salt (2) is involved in six hydrogen bonds to five 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations, which is attributed to the smaller size and reduced polarizability of the chloride ion compared to the iodide ion. In the IR spectra, the pyridinium N—H stretching band for salt (1) exhibited a blue shift compared with that of salt (2).     

Functionalization of polyesters with maleic anhydride by reactive extrusion

Maleic anhydride (MAn) was grafted onto aliphatic and aromatic/aliphatic copolyesters by reactive extrusion in the presence of a free radical initiator using a twin‐screw extruder. The grafting reaction was confirmed by spectroscopic analyses. The presence of succinic anhydride groups was shown by FT‐IR spectroscopy, and NMR spectra indicate that the grafts consist of single succinic anhydride units. The 2D ¹H‐NMR spectra (COSY) indicate that grafting reactions take place at aliphatic dicarboxylic acid units of copolyesters. The graft content was determined by a nonaqueous titration method. The effects of concentration of initiator and monomer and reaction temperature on the graft content and intrinsic viscosity were studied. The low percentage grafting in poly(lactic acid) was observed due to the presence of limited free radical sites in the polymer backbone. Temperature and monomer and initiator concentrations affect the graft content, and the desired graft content with minimal degradation can be obtained by controlling these factors. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1693–1702, 1999     

Synthesis, structure and catalytic properties of [Cp*Cr(C6F5)(Bn)(THF)] toward ethylene in the presence of AlEt3

Treatment of [Cp*CrCl(C₆F₅)]₂ with BnMgCl (Bn = benzyl) in Et₂O/THF affords [Cp*Cr(C₆F₅)(Bn)(THF)] (1) which has been isolated in 72% yield. This compound whose magnetic moment is equal to of 4.037 μ_B has been characterized by NMR and single crystal X-ray analysis. Compound 1 alone does not polymerize ethylene when dissolved in toluene. However, addition of excess AlEt₃ to a solution of 1 in toluene leads to a catalytically active system which readily oligomerizes ethylene under standard conditions. Oligomerization experiments carried out with [1] = 10⁻³ M and [AlEt₃] = 9 × 10⁻² M for 15 min lead to the production of ethylene oligomers with an activity of 280 kg mol Cr⁻¹ h⁻¹. The experimental molecular weight distribution observed at intermediate times during the reaction is satisfactorily accounted for by the Poisson distribution formula, which is indicative of a living polymerization system. These observations are in agreement with a catalytic cycle in which the growing alkyl chain is transferred from chromium to aluminum via a bimetallic complex in which the chromium and aluminum centers are bridged by an alkyl group and the growing polymer chain.     

Radioimmunoassay of Human Follicle Stimulating Hormone /HFSH/

A method for determining Human FSH in blood/serum by RIA is described. The radioiodination of FSH with¹²⁵I is carried out under carefully controlled conditions such as, amount of initial activity of¹²⁵I take for iodination, the reaction volume, and the reaction time, etc. The tracer FSH obtained thus is with minimum damage and optimum specific activity which is ideally suited for RIA. The shelf-life of the tracer is enhanced by the addition of benzyl alchol. The tracer can be conveniently stored at+4–6°C upto 10 weeks, avoiding the repeated freezing and thawing process. Antiserum to FSH is raised in rabbits by repeated injections via intramuscular route. The method utilizes polyethylene glycol /PEG/ as the separation system. Using this method, a number of control samples of men and women of reproductive age group are screened. This sensitive assay has a good validity and has an inter-assay variation less than 15%.     

A rapid radioimmunoassay procedure for thyroxin

A sensitive thyroxin /T₄/ radioimmunoassay procedure with a short incubation time /10 min/ similar to a conventional stat test in clinical chemistry is described. The assay parameters such as concentration of antisera and¹²⁵I-T₄, and incubation temperature that affect the kinetics of antigen-antibody reaction have been studied. Within- and between-assay variations were less than 7% CV. Analysis of 45 serum samples by the proposed method and by a conventional assay gave similar results /Y=1.05X–0.187; r=0.990/.     

Synthesis of 2,3-dimethyltetra-cyclo(5.5.1.04,13.010,13)trideca-2,5-dien-9-one,a new derivative of all-cis-(5.5.5.5)fenestrane

Intramolecular arene-olefin photoreaction of methyl-6-methyl-2-phenylhept-5-enoate (9a) leads to the tetracyclic product 10a, from which the fenestra-dienone, 2, has been obtained. Mechanistic aspects of the photoreaction are discussed.     

Gelatin Nanoparticles with Enhanced Affinity for Calcium Phosphate

Gelatin nanoparticles can be tuned with respect to their drug loading efficiency, degradation rate, and release kinetics, which renders these drug carriers highly suitable for a wide variety of biomedical applications. The ease of functionalization has rendered gelatin an interesting candidate material to introduce specific motifs for selective targeting to specific organs, but gelatin nanoparticles have not yet been modified to increase their affinity to mineralized tissue. By means of conjugating bone‐targeting alendronate to biocompatible gelatin nanoparticles, a simple method is developed for the preparation of gelatin nanoparticles which exhibit strong affinity to mineralized surfaces. It has been shown that the degree of alendronate functionalization can be tuned by controlling the glutaraldehyde crosslinking density, the molar ratio between alendronate and glutaraldehyde, as well as the pH of the conjugation reaction. Moreover, it has been shown that the affinity of gelatin nanoparticles to calcium phosphate increases considerably upon functionalization with alendronate. In summary, gelatin nanoparticles have been developed, which exhibit great potential for use in bone‐specific drug delivery and regenerative medicine.

     

Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of conjugated 3-(benzylidene/salicylidene)-β-diketones (having no enolisable γ-carbon proton) and their reactions

Transition Metal Chemistry - The synthesis and structural characterization of new metal(II) chelates (M = CoII, NiII, CuII and ZnII) of neutral conjugated bidentate β-diketone ligands, having...     

Biogenic Synthesis of Rod Shaped ZnO Nanoparticles Using Red Paprika (Capsicum annuum L. var. grossum (L.) Sendt) and Their in Vitro Evaluation

Journal of Cluster Science - Metal oxide nanoparticles (NPs) have gained attention in biomedicine due to their broad spectrum of applications, such as targeted drug delivery, their use as...