MNPs

ESR studies on the initial free radicals were carried out by using MNP(2-methyl-2-nitrosopropane) or DMPO (5,5-dimethylpyrroline N-oxide) as the spin-trapping agent. The reactions are shown as ... 

The spin adducts of free radicals and MNP or DMPO were observed by means of an ESR spectrometer. The data of hyperfine splitting constants were compiled in Tables 9 and 10 [40-42,44,45]. ESR studies on the initial free radicals revealed that the monoalkylamino radical RHN-, dialkylamino radical R2N-, and aminomethyl radical -CH2N< or aminoethylidene radical >N( CHCH3) were obtained from the corresponding primary, secondary, and cyclic tertiary amine. In case of a tertiary diamine such as TMEDA, formation of... 

Table 9 Hyperfine Splitting Constants of Spin Adduct Formed APS/Amine/MNP or DMPO System ...

Tabie 10 Hyperfine Splitting Constants of Spin Adducts Obtained from APS/Amine/MNP Systems... 

System Radical trapped by MNP Hyperfine splitting constant (0.1 mT) ap ap a," ... 

The initial radicals formed from the reaction of Ce(IV) ion and reductant systems can be trapped by MNP. The spin adducts of the initial radicals and MNP were observed by means of an ESR spectrometer. The structure of the initial radicals and the hypeiTme splitting constants of the spin adduct of the radical with MNP and tt-phenyl-N-/er/-butylnitrone (PBN) are compiled in Tables 5 and 6, respectively. 

The formation of spin adducts from radicals and MNP is as follows ... 

Table 5 HyperTme Splitting Constants of CAN-Reductant-MNP Systems [20,36,38,40]...

Reductant Radical trapped by MNP Hyperfme splitting constant (mT) a N a ... 

Based on the ESR studies of Ce(IV) ion-BzyAcAc-MNP, Ce(IV) ion BzAc-MNP systems as mentioned before, the grafting reaction of P(St-CH2-AcAc) will take place on the methene carbon of 1,3-dikeone via the abstraction of hydrogen by the Ce(I V) ion to form radicals and then initiate monomer graft copolymerization. The initiation mechanism of graft copolymerization is proposed in Scheme (10). 

However, it may seem that we have ignored the m, n, and p odd combinations that are also possible. For example, in jamesonite, Fe"Pb4Sb5Si4 [80], the mnp values are 034 (or 068), respectively (assuming one Fe(II) = 2 Cu(I)). We have successfully substituted europium into the structure to create a congru-ently melting, semiconducting FePb2Fu2Sb6Si4 [79]. This has a value of A B =... 

Biphenyl-2,2 -dicarboxylate was formed by Ph. chrysosporium in a reaction mixture with manganese peroxidase, Oj, and unsaturated lipid, and it was suggested that a MnP-mediated lipid peroxidation was involved (Moen and Hammel 1994). 

Figure 20. Selective cell targeting via specific monoclonal antibodies and/or antibody fragments directed against cancer cells and linked to the free amino groups of L-cysteine-coated metallic-core magnetic nanoparticles (MNP) (MNP = Co, Fe/Co, size 8-10 nm).

The NiAs structure and distorted variants. The images for MnP and NiP show the same section as the image for NiAs in the upper left. 

The structure of MnP is a distorted variant of the NiAs type the metal atoms also have close contacts with each other in zigzag lines parallel to the a-b plane, which amounts to a total of four close metal atoms (Fig. 17.5). Simultaneously, the P atoms have moved up to a zigzag line this can be interpreted as a (P-) chain in the same manner as in Zintl phases. In NiP the distortion is different, allowing for the presence of P2 pairs (P ). These distortions are to be taken as Peierls distortions. Calculations of the electronic band structures can be summarized in short 9-10 valence electrons per metal atom favor the NiAs structure, 11-14 the MnP structure, and more than 14 the NiP structure (phosphorus contributes 5 valence electrons per metal atom) this is valid for phosphides. Arsenides and especially antimonides prefer the NiAs structure also for the larger electron counts. 

The symmetry reduction to the mentioned hettotypes of diamond is necessary to allow the substitution of the C atoms by atoms of different elements. No splitting of Wyckoff positions, but a reduction of site symmetries in necessary to account for distortions of a structure. Let us consider once more MnP as a distorted variant of the nickel arsenide type (Fig. 17.5, p. 197). Fig. 18.4 shows the relations together with images of the structures. 

By the addition of, , 0 to the coordinates listed in Fig. 18.4 for the space group Cmcm, we obtain ideal values for an undistorted structure in Pmcn. However, due to the missing distortion the symmetry would still be Cmcm. The space group Pmcn is only attained by the shift of the atoms from the ideal positions. First of all, the deviations concern the y coordinate of the Mn atom (0.214 instead of ) and the z coordinate of the P atom (0.207 instead of ). These are rather small deviations, so we have good reasons to consider MnP as being a distorted variant of the NiAs type. 

MnAs exhibits this behavior. It has the NiAs structure at temperatures exceeding 125 °C. When cooled, a second-order phase transition takes place at 125 °C, resulting in the MnP type (cf. Fig. 18.4, p. 218). This is a normal behavior, as shown by many other substances. Unusual, however, is the reappearance of the higher symmetrical NiAs structure at lower temperatures after a second phase transition has taken place at 45 °C. This second transformation is of first order, with a discontinuous volume change AV and with enthalpy of transformation AH. In addition, a reorientation of the electronic spins occurs from a low-spin to a high-spin state. The high-spin structure (< 45°C) is ferromagnetic,... 

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