Abstract:The reactivity of the bifunctionalized ligand NC(Br)N-I 1 [IC6H2(CH2NMe2)2-3,5-Br-4] has been studied as a versatile synthon for organic and/or organometallic synthesis. Chemoselective metalation (M ) Pd, Pt, Li) at the Caryl-I or Caryl-Br bonds was achieved by choosing the appropriate metal precursors. In this way a series of Pt II and Pd II complexes were prepared that have a second functional group available for further reactions. These Pt II and Pd II complexes were subjected to a wide range of organic and organometallic reactions, revealing the remarkable stability of their M-C σ-bond and opening an easy route for the synthesis of mono-and (hetero)bimetallic building blocks. The scope of the chemistry of such building blocks shows that they are good candidates for use in the synthesis of dendrimers, bioorganometallic systems, or polymetallic materials. The X-ray crystal structures of the most representative complexes (2, 3a, 19, 20, and 24) are also reported.

Water-and acid-resistant arylplatinum(II) complexes have been covalently bonded to the N-terminus of L-valine, thus providing organometallic biomolecules with excellent stability properties. Owing to the 195 Pt nucleus (I ) 1 / 2 ), these building blocks are potentially versatile biomarkers (e.g., MRI). Moreover, they display efficient in vitro biosensor characteristics since they detect SO 2 gas selectively and fully reversibly by an instantaneous change of the spectroscopic properties including a diagnostic 195 Pt NMR signal.

Tailoring the properties of magnetic vortices through the preparation of structured multilayers is discussed. The dependence of the vortex core radius r on the effective anisotropy is derived within a simple model, which agrees with our simulations. As the perpendicular anisotropy increases, r also increases until a perpendicular magnetization appears in the disk rim. Co/Pt multilayer disks were studied; x-ray microscopy confirms qualitatively the predicted behavior. This is a favorable system for implementing vortex-based spin-transfer nano-oscillator devices, with enhanced rf power resulting both from the increase in the core size and synchronization afforded by the coupling of the Co layers.

Systematic measurements of giant magneto-impedance (GMI) and its relaxation (magneto-impedance aftereffect) have been carried out in a series of Co-rich amorphous ribbons ranging in magnetostriction values from −3.5 to +3.5 ppm. The value of GMI is a maximum for the alloy with the lowest value of magnetostriction, corresponding to a maximum of the transverse permeability. The impedance relaxation between two fixed times depends on the magnetostriction constant (λs) of the samples, and the observed trend is consistent with the theories which predict a direct relationship of the conventional permeability aftereffect (MAE) with the square of λs. Furthermore, the variation of the impedance aftereffect with the driving current resembles the behavior of MAE, and a connection between both effects can be established.

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Tailoring magnetic flux distribution is highly desirable in a wide range of applications such as magnetic sensors and biomedicine. In this paper we study the manipulation of induced currents in passive devices in order to engineer the distribution of magnetic flux intensity in a given region. We propose two different approaches, one based on especially designed wire loops (Lenz law) and the other based on solid conductive pieces (eddy currents). The gain of such devices is mainly determined by geometry giving perspective of high amplification. We consistently modeled, simulated, and executed the proposed devices. Doubled magnetic flux intensity is demonstrated experimentally for a moderate aspect ratio.

SummaryThis paper reports on the development of a magneto-optical scanning near-field optical microscope and the experimental near-field study of the domain structure for a model magnetic particle of 16 × 16 µ m 2 of a Co 70.4 Fe 4.6 Si 15 B 10 amorphous thin film, deposited on a silicon substrate. We present the topographic, optical and magneto-optical differential susceptibility (MODS) images of the particle. Imaging by using the local MODS reveals the domain structure. These images are also used for positioning the tip in order to acquire local hysteresis loops, with submicrometre spatial resolution.

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