| Autor: |
Padden, K. M., Krebs, J. F., Trafford, K. T., Yap, G. P. A., Rheingold, A. H., Borovik, A. S., Scarrow, R. C. |
| Zdroj: |
Chemistry of Materials; November 19, 2001, Vol. 13 Issue: 11 p4305-4313, 9p |
| Abstrakt: |
Template copolymerization methods have been used to make materials for a wide variety of applications where site-specific analyte binding is desired. The structure of the binding site is often crucial to the efficient function of the material. We have immobilized cobalt-containing template complexes in porous organic hosts, allowing the use of spectroscopy to conveniently probe the site structure. Reported herein are results from X-ray diffraction and X-ray absorption spectroscopy (XAS) studies for a series of monomers {[CoIII1(dmap)2][PF6] and [CoIII2(1-MeIm)][PF6], where 1 is the ligand bis[2-hydroxy-4-(4-vinylbenzylmethoxy)benzaldehyde]ethylenediimine and 2 is bis[2-hydroxy-4-(4-vinylbenzylmethoxy)benzyliminopropyl]methyl amine} and related copolymers. Copolymerization of the 6-coordinate complex [CoIII1(dmap)2][PF6] with an organic cross-linker forms immobilized 6-coordinate cobalt sites in P-1[CoIII(dmap)2]. Similar findings were obtained for the formation of immobilized cobalt sites in P-2[CoIII(1-MeIm)]. Demetalation of P-1[CoIII(dmap)2] and P-2[CoIII(1-MeIm)] affords immobilized sites that contain tetra- or pentadentate ligands, respectively. Rebinding of CoII ions affords P-1[CoII] with sites containing cobalt complexes having square planar coordination geometry, whereas P-2[CoII] has immobilized square pyramidal cobalt complexes. XAS studies support these coordination geometry assignments and show that the rigidity of the porous host maintains site architecture even after chemical modification. |
| Databáze: |
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