We explored using a magnetic field to modulate the permeability of polyelectrolyte microcapsules prepared by layer-by-layer self-assembly. Ferromagnetic gold-coated cobalt (Co@Au) nanoparticles (3 nm diameter) were embedded inside the capsule walls. The final 5 mum diameter microcapsules had wall structures consisting of 4 bilayers of poly(sodium styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH), 1 layer of Co@Au, and 5 bilayers of PSS/PAH. External alternating magnetic fields of 100-300 Hz and 1200 Oe were applied to rotate the embedded Co@Au nanoparticles, which subsequently disturbed and distorted the capsule wall and drastically increased its permeability to macromolecules like FITC-labeled dextran. The capsule permeability change was estimated by taking the capsule interior and exterior fluorescent intensity ratio using confocal laser scanning microscopy. Capsules with 1 layer of Co@Au nanoparticles and 10 polyelectrolyte bilayers are optimal for magnetically controlling permeability. A theoretical explanation was proposed for the permeability control mechanisms. "Switching on" of these microcapsules using a magnetic field makes this method a good candidate for controlled drug delivery in biomedical applications.

Dynamic microwave properties of arrays of circular Ni and Ni81Fe19 dots were studied by X-band ferromagnetic resonance (FMR) technique. All of the dots had the same radius 0.5μm, thickness 50–70nm, and were arranged into rectangular or square array with different interdot separations. In the case of perpendicular magnetization multiple (up to 8) sharp resonance peaks were observed below the main FMR peak, and the relative positions of these peaks were independent of the interdot separations. Quantitative description of the observed multiresonance FMR spectra is given using the dipole-exchange spin wave dispersion equation for a perpendicularly magnetized film where in-plane wave vector is quantized due to the finite dot radius, and the inhomogenetiy of the intradot static demagnetization field in the nonellipsoidal dot is taken into account.

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Organized multilayers of nanoparticles (9-, 20-, and 45-nm-diameter silica or 12-nm magnetite) and glucose oxidase (GOx) were assembled in alternation with oppositely charged polyelectrolytes on 420-nm latex particles. Stepwise growth of the multilayer films on latex was confirmed by microelectrophoresis and transmission electron microscopy. The inclusion of silica layers on latex yields a higher surface area, resulting in greater GOx adsorption and thereby increasing the catalytic activity of the bioreactor. The bioactivity was proportional to the core surface area and also to the number of GOx layers in the shells. Also, the presence of magnetic nanoparticles allows self-stirring of the nanoreactors with a rotating magnetic field and enhances its productivity. The ensemble of GOx and fluorescent dyes in the shells demonstrated the correlation between Ru-bpy fluorescence and glucose concentration in solution.

The reactions of the Re(V) starting material [ReO(PPh(3))(2)Cl(3)] with ligands of the type XN(Y)Z [X = Y = 2-pyridylmethyl, Z = -CH(2)CO(2)Et (L(1)Et), -CH(2)CH(2)CO(2)Et (L(2)Et), -CH(2)CH(2)CH(2)CH(2)CH(NHCO(2)Bu(t))CO(2)H (L(3)H); X = 2-pyridylmethyl, Y = 2-(1-methylimidazolyl)methyl, Z = -CH(2)CO(2)Et (L(4)Et)] yielded the Re(III) trichloride complexes of the type [ReCl(3)(L(n)R)]. The complexes are mononuclear, paramagnetic species with a facial geometry of the chloride ligands. The nitrogen donors of the tridentate L(n)()R ligands complete the distorted octahedral coordination spheres of the complexes. Crystal data: [ReCl(3)(L(1)Et)] (1), monoclinic, C2/m, a = 16.088(3) A, b = 9.980(2) A, c = 12.829(2) A, beta = 91.384(3) degrees, Z = 4, D(calc) = 1.967 g/cm(-)(3); [ReCl(3)(L(4)Et)] (4), monoclinic, C2/c, a = 22.880(1) A, b = 7.4926(4) A, c = 22.560(1) A, beta = 94.186(1) degrees, Z = 8, D(calc) = 2.001 g/cm(-3).

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The oxomolybdenum-arsonate system was investigated under hydrothermal conditions in the presence of charge-compensating copper(II)-organonitrogen complex cations as secondary building blocks. A series of materials of the Mo/O/As/Cu/ligand family has been prepared and structurally characterized. The architectures of the products reflect the identity of the arsonate component and the organonitrogen ligand, as well as the reaction conditions. The structural versatility of this emerging class of compounds is manifested by the one-dimensional structures of [[Cu(o-phen)(H(2)O)(2)](2)Mo(6)O(18)(O(3)AsOH)(2)] (1), [[Cu(terpy)](2)Mo(4)O(13)H(AsO(4))(2)].2H(2)O (2.2H(2)O), [[Cu(2,2'-bpy)(H(2)O)](2)Mo(6)O(18)(O(3)AsC(6)H(5))(2)].2H(2)O (4.2H(2)O), and [[Cu(o-phen)(H(2)O)](2)[Mo(6)O(18)(O(3)AsC(6)H(5))(2)]].4H(2)O (5.4H(2)O), by the two-dimensional materials [[Cu(2)(tpyprz)(H(2)O)(2)]Mo(6)O(18)(O(3)AsOH)(2)].2H(2)O (3.2H(2)O), [[Cu(terpy)](2)Mo(6)O(18)(O(3)AsC(6)H(5))(2)].H(2)O (6.H(2)O), and [[Cu(2)(tpyprz)]Mo(6)O(18)(O(3)AsC(6)H(5))(2)].2H(2)O (7.2H(2)O), and the molecular clusters [[Cu(2,2'-bpy)(2)](2)Mo(12)O(34)(O(3)AsC(6)H(5))(4)].2.35H(2)O (8.2.35H(2)O) and [Cu(o-phen)(H(2)O)(3)][Cu(o-phen)(2)Mo(12)O(34) (O(3)AsC(6)H(5))(4)].3H(2)O (9.3H(2)O).

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