Efficient ligandless palladium-catalyzed Suzuki reactions of potassium aryltrifluoroborates

[reaction: see text] The ligandless palladium-catalyzed Suzuki cross-coupling reaction of potassium aryl- and heteroaryltrifluoroborates with aryl- or heteroaryl halides or triflates proceeds readily with very good yields. The cross coupling can be effected in methanol or water, in the open air, using Pd(OAc)(2) as a catalyst in the presence of K(2)CO(3). A variety of functional groups are tolerated.     

Ionic silica based hybrid material containing the pyridinium group used as an adsorbent for textile dye

The present study reports the development of an ionic silica based hybrid material containing the cationic pyridinium group, which was employed for the removal of the Reactive Red 194 textile dye from aqueous solution. Three hybrid material samples were prepared with planned textural and chemical properties, varying the inorganic precursor molar percentage in the sol-gel synthesis. The obtained samples were defined as Py/Si-90, Py/Si-92 and Py/Si-94, where the number specifies the inorganic molar percentage. The hybrid samples were characterized by elemental, infrared, (13)C and (29)Si NMR, N(2) adsorption-desorption isotherms and thermogravimetric analyses. The dye-removing ability of these adsorbents was determined by the batch contact adsorption procedure. Effects such as pH value and adsorbent dosage on the adsorption capacities were studied. Four kinetic models were applied. The adsorption was best fitted to Avrami fractional-order kinetic model for the three hybrid material samples. The kinetic data were also adjusted to an intra-particle diffusion model resulting three linear regions, indicating that the adsorption kinetics follows multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich and Liu isotherm models. The maximum adsorption capacities were 165.4, 190.3 and 195.9 mg g(-1) for Py/Si-90, Py/Si-92 and Py/Si-94, respectively. Simulated dye-house effluents were used to check the applicability of the proposed adsorbents for effluent treatment. Dye loaded adsorbents were regenerated (>98.2%) by using 0.4 mol L(-1) of NaOH solution as an eluent.     

Poly(vinyl alcohol) physical hydrogels: noncryogenic stabilization allows nano- and microscale materials design

Physical hydrogels based on poly(vinyl alcohol), PVA, have an excellent safety profile and a successful history of biomedical applications. However, highly inhomogeneous and macroporous internal organization of these hydrogels as well as scant opportunities in bioconjugation with PVA have largely ruled out micro- and nanoscale control and precision in materials design and their use in (nano)biomedicine. To address these shortcomings, herein we report on the assembly of PVA physical hydrogels via "salting-out", a noncryogenic method. To facilitate sample visualization and analysis, we employ surface-adhered structured hydrogels created via microtransfer molding. The developed approach allows us to assemble physical hydrogels with dimensions across the length scales, from ～100 nm to hundreds of micrometers and centimeter sized structures. We determine the effect of the PVA molecular weight, concentration, and "salting out" times on the hydrogel properties, i.e., stability in PBS, swelling, and Young's modulus using exemplary microstructures. We further report on RAFT-synthesized PVA and the functionalization of polymer terminal groups with RITC, a model fluorescent low molecular weight cargo. This conjugated PVA-RITC was then loaded into the PVA hydrogels and the cargo concentration was successfully varied across at least 3 orders of magnitude. The reported design of PVA physical hydrogels delivers methods of production of functionalized hydrogel materials toward diverse applications, specifically surface mediated drug delivery.     

Thin-layer chromatography of mycotoxins

TLC has become an extremely powerful, rapid and in most instances inexpensive separation technique in mycotoxicology. This review presents achievements of its applications in this field. General technical aspects of the TLC of mycotoxins that are discussed include extraction and clean-up procedures, adsorbents and solvent systems, detection methods, two-dimensional TLC, high-performance TLC (HPTLC), quantitation and preparative TLC (PLC). Special applications of TLC deal with multi-mycotoxin analyses and with structurally related or individual mycotoxins (aflatoxins, sterigmatocystins, versicolorins, ochratoxins, rubratoxins, patulin, penicillic acid, mycophenolic acid, butenolide, citreoviridin, trichothecenes, cytochalasans, tremorgenic toxins, epipolythiopiperazine-3,6-diones, hydroxyanthraquinones, zearalenone, citrinin, secalonic acids, cyclopiazonic acid, PR toxin, roquefortine, xanthomegnin, viomellein and naphtho-gamma-pyrones).