Research on the structure and properties of organometals at the boundary surface of polymers or nanoparticles using novel diffusion and surface layer resolved NMR methods

High resolution Magic Angle Spinning (hr-MAS) NMR and Diffusion Ordered SpectroscopY (DOSY) NMR are explored as innovative research and analysis tools in inorganic and metallorganic chemistry.
Hr-MAS NMR enables one to perform advanced structural characterizations of molecules grafted onto insoluble polymer supports, directly in situ, at the boundary between liquid and material, which yields NMR spectra having essentially high resolution spectral features as obtained in homogeneous solution. Organotin derivatives grafted onto insoluble, cross-linked polystyrenes (P-H) of the type (P-H)(1-t)(P-(CH2)nSnBuX2)t and (P-H)(1-2t)([P-(CH2)nSnBuY]2O)t (n = 4, 6; X = Ph, Cl; Y = Cl, OH; t = functionalization degree) will be investigated with the goal to find out to which extent 1H, 13C and 119Sn, 1D or 2D hr-MAS NMR techniques can force a breakthrough in the well-known issue of insufficient structure characterization of such materials, which, as a consequence of their insolubility, can be characterized only to a limited extent by a few solid-state analytical methods (CP-MAS NMR, IR, TGA).

DOSY NMR discriminates between structural units in mixtures on the basis of their different translational diffusion rates. Differences in diffusion time constants are unravelled simultaneously in DOSY NMR spectra for all structural units in a mixture without any need to preliminary separation; this enables one to detect directly intermolecular interactions between macromolecular structures and substrates in solution. The potentials of this class of techniques will be explored with the determination of diffusion time constants, for the cationic model nanocluster [(BuSn)12O14(OH)6]2+ interacting with different anions as well as for tin- and titanium dioxide based nanostructures which are treated with chelating organic ligands in solution in order, for applications, to design perfectly tailored metal oxide particles using cheap sol-gel processes. In this way, it is expected to get better insight into the chemical mechanisms which determine the formation of such particles, which should lead to the optimalization of the associated synthetic procedures.