Cobalt coordination polymers

A third method of solving the kinetics dilemma is to use organic reactions with functionalized inert coordination compunds. An example of a cobalt(III) polymer which has been prepared in this manner is shown below. 

In metal-containing systems, synthons involving coordinated water or am-mine ligands are possible. For example, hydrogen bonding between coordinated water and pyridine oxide ligands in a R2(8) motif has been observed to link cobalt 4,4 -bipyridine dioxide coordination polymers into sheets [60]. 

Vaucher, S., Fielden, J., Li, M., Dujardin, E. andMann, S. (2002) Molecule-based magnetic nanoparticles Synthesis of cobalt hexacyanoferrate, cobalt pentacyanonitrosylferrate, andchromium hexacyanochromate coordination polymers in water-in-oil emulsion. Nano Lett., 2, 225-229. 

Colloidal metal clusters, which offer a high surface area for better activity, have been stabilized by polymers. Thus, a homogeneous dispersion of a cobalt-modified platinum cluster was stabilized by a coordinating polymer, poly(/V-vinyl-2-pyrrolidone).74 Addition of the cobalt(II) [or iron(III)] doubled the activity and increased the selectivity from 12 to 99% when the catalyst was used to reduce cin-namaldehyde (5.23). 

A second important focus of our work is the development of suitable analytical methods for the solid state and in solution. The physical characterization of metallo-supramolecular systems has mainly relied on crystal structure determination. Studies have also been performed on surface layers 40-42). The classical analytical methods (like FAB mass spectrometry) or most polymer methods (like light scattering, vapor pressure osmometry or membrane osmometry) can not be used. In solution, ESI mass spectrometry (43-45) and NMR (27,46) have been succesfully applied. We have explored whether MALDI-TOF mass spectrometry in the solid state (Schubert, U. S. Lehn, J.-M. Weidl, C. H. Spickermann, J. Goix, L. Rader, J. Mullen, K., unpublished data.) and sedimentation equilibrium analysis in the analytical ultracentrifuge for solutions may be employed. Grid-like cobalt coordination arrays ([2 X 2] Co(n)-Grid) were used as model systems in the analytical ultracentrifuge (47). 

Fig. 16 Views and magnetic properties of the open-framework coordination polymers based on cobalt imidazolates. (a) Evacuated [Co(im)J-0 5Ch. (b) [Co(im)j4- (c) [Co(im)j]j. (d) [Co5(im)j 0.4Mb]j. (e) Plots of temperature dependence of ac susceptibility obtained at 0.1 Oe field for [Co(im)J 0.5Ch. A peak appears at 15 K, which is indicative of the ferromagnetic character of this compound, (f) Plot of the thermal evolution of the for [CoCiml lj at 10 kOe field. The inset shows the hysteresis loop at 1.8 K ( ) and 5.0 K (o). (Co, blue O, red C, brown N, violet H, white. Solvent guest molecules in (d) are represented as spheres) Reprinted from ref 168 [Tian YQ, Cai C-X, Ren X-M, Duan C-Y, Xu Y, Gao S, You X-Z, The SUica-Like Extended Polymorphism of Cobalt(ll) Imidazolate Three-Dimensional Erameworks X-ray Single-Crystal Structures and Magnetic Properties (2003) Chem Eur 1 9 5673]. Copyright WUey-VCH Verlag GmbH Co. KGaA. Reproduced with permission...

Reaction of the coordinating polymers with metals. The reaction of C0CI2 with PP-gr-4-VPy resulted in the bonding of Co(II) to the polymer through a coordinative pyridine-cobalt interaction (11). C0CI2 can be fixed onto PE-gr-PVIA in the same way. The reaction of PE-gr-PAVK with cobalt acetate in alcohol leads to chelate complexes of the type shown below (12) ... 

Therefore, in order to get the advantage of the heavier atoms together with the sensitivity of the organic polymers containing sulfide and sulfone bridges, we have synthesized several cobalt(III) coordination polymers, one of which was briefly described earlier (13,14). The general synthesis for three of the polymers derived from leucinatobis(2,4-pentane-dionato)cobalt(III), Co(leu)(acac)2, is shown in equations (1) - (5) ... 

Linear coordination polymers of cobalt(III) have been prepared from... 

Schareina. T. Schick. C. Abrahams. B.F. Kempe. R. Coordination polymers of bipyridyldicarhorcylates—A cobalt containing 12,3-net with potential reactive sites. Z. Anorg. Allg. Chem. 2001. 627. 1711-1713. 

The second example relates to a functional nanopo-rous material based on the siipramolecular assembly of the CoTCPP tectons, which was fabricated by Suslick et al. with the aid of solvothermal techniques.Its structure is based on peripheral coordination of the porphyrin building blocks to each other, into a three-dimensional coordination polymer, with the aid of external cobalt ion auxiliaries (Fig. 7). The bending of... 

Cheng L, Wang JQ, Gou SH. A new three-dimensional cobalt(II) coordination polymer based on biphenyl-2,2 6,6 -tetracarboxylic acid and 1,2,4-triazole synthesis, crystal structure and magnetic properties. Inorg Chem Commun 2011 14(1) 261. ... 

Bedioui, R, M. Voisin, J. Devynck, and C. Bied-Charreton (1991). Electrochemistry of conducting polypyrrole films containing cobalt porphyrin. 2. New developments and inclusion of metallic aggregates in the coordination polymer. J. Electroanal. Chem. 297, 257-269. 

Figures A schematic representation of supramolecular polymer formation via porphyrin/cobalt coordination (adapted from U. Michelsen and C.A. Hunter. Angew. Chem. Int. Ed. 39 764-767, 2000.).

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