Magnets microporous solids

In the world of nanoparticles and microporous materials, the interaction forces between nanosized particles and molecules from the surrounding medium, or the forces between particles themselves, may exceed the mechanical forces between bodies of the macroscopic world. This is caused by the high surface-to-volume ratio of nanoparticles and microporous materials. When familiar materials become mainly surface, they acquire new optical, magnetic, electrical, chemical, and transport properties. Thus, dispersions tend to agglomerate, fine particles show increased mechanical strength, and microporous solids develop tremendous sorption and molecular sieving properties. 

Selected signature libraries may be immobilized on a solid matrix such as activated silica resin, cellulose microporous modified membranes [66], Sepharose , magnetic beads based on MagaPhase technology. The affinity support obtained is used for IgM antibodies parting. 

Feuerstein M., Engelhard G., McDaniel P. L., MacDougall J. E. and Gaffney T. R., Solid state nuclear magnetic resonance investigation of cation siting in LiNaLSX zeolites. Microporous and Mesoporous Materials 26 (1998) pp. 27-35... 

We are interested in vanadoborate cluster materials both as precursors to porous solids and as a new class of molecular magnets. We have synthesized a variety of vanadoborate cluster compounds 1-7, primarily by use of two different synthetic routes. The first involves hydrothermal synthesis, using sodium tetraborate ( borax ) as the boron source and the second uses molten boric acid as the reaction medium. In general anionic clusters are found. Herein we report that these have novel electronic and bonding arangements which affect their magnetic behaviour and also that they may be cross-linked together by metal centers such as Cd to form stable microporous phases. 

Some information can be obtained on porous media from conventional NMR spectroscopy, and this is discussed in Section 2. Relaxation time measurements have been widely used to characterize porous solids, and this technique is discussed in Section 3. Pulsed field gradient (PFG) methods may be used to probe the local structure of the pore space and to characterize transport within it, and these are discussed in Section 4. Magnetic resonance imaging (MRI) techniques can also be used to characterize the pore space and to measure transport, and applications are discussed in Section 5. The bulk of this review will be concerned with mesoporous and macroporous materials, as it is for these systems that NMR is particularly useful in characterizing the pore space. However, some applications of NMR techniques to probe the pore space and transport within microporous materials will be mentioned in Section 6. Finally, some general conclusions are given in Section 7. 

Zinc-phosphite and -phosphate based microporous materials are crystalline open framework materials with potential industrial applications. These were characterised by P MAS NMR and for the first time Zn NMR. In this work the local structure around the Zn centres in several representative microporous zinc phosphites and zinc phosphates was characterised by acquiring natural abundance Zn solid-state NMR spectra at ultrahigh magnetic field of 21.1 T. 

Fyfe, C.A., Wong-Moon, K.C., Huang, Y., and Grondey, H. 1995. Structural investigations of S APO-37 molecular sieve by coherence-transfer and dipolar-dephasing solid-state nuclear magnetic resonance experiments. Micropor. Mater. 5 29-37. 

Zr and Mg solid-state NMR was used to examine the local environments around the metal centres in microporous zirconium silicates and an aluminophosphate incorporated with Mg. QCPMG spectra were obtained at different magnetic fields from which the quadrupolar and chemical shift parameters were extracted. ... 

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