Brandès Stéphane, David Gabriel, Suspène Clément, Corriu Robert J P, Guilard Roger
LIMSAG, UMR 5633, Université de Bourgogne, UFR Sciences et Techniques, 9 avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France.
Chemistry. 2007;13(12):3480-90. doi: 10.1002/chem.200601166.
We report the exceptional reactivity towards dioxygen of a nanostructured organic-inorganic hybrid material due to the confinement of copper cyclam within a silica matrix. The key step is the metalation reaction of the ligand, which can occur before or after xerogel formation through the sol-gel process. The incorporation of a Cu(II) center into the material after xerogel formation leads to a bridged Cu(I)/Cu(II) mixed-valence dinuclear species. This complex exhibits a very high affinity towards dioxygen, attributable to auto-organization of the active species in the solid. The remarkable properties of these copper complexes in the silica matrix demonstrate a high cooperative effect for O(2) adsorption; this is induced by close confinement of the two copper ions leading to end-on mu-eta(1):eta(1)-peroxodicopper(II) complexes. The anisotropic packing of the tetraazamacrocycle in a lamellar structure induces an exceptional reactivity of these copper complexes. We show for the first time that the organic-inorganic environment of copper complexes in a silica matrix fully model the protecting role of protein in metalloenzymes. For the first time an oxygenated dicopper(II) complex can be isolated in a stable form at room temperature, and the reduced Cu(2) (I,I) species can be regenerated after several adsorption-desorption cycles. These data also demonstrate that the coordination scheme and reactivity of the copper cyclams within the solid are quite different from that observed in solution.
我们报道了一种纳米结构的有机-无机杂化材料对氧气具有异常的反应活性，这是由于环四胺铜被限制在二氧化硅基质中。关键步骤是配体的金属化反应，该反应可在通过溶胶-凝胶法形成干凝胶之前或之后发生。在干凝胶形成后将Cu(II)中心掺入材料中会导致形成桥联的Cu(I)/Cu(II)混合价双核物种。这种配合物对氧气表现出非常高的亲和力，这归因于固体中活性物种的自组装。这些二氧化硅基质中的铜配合物的显著性质表明对O(2)吸附具有很高的协同效应；这是由两个铜离子的紧密限制导致端基μ-η(1):η(1)-过氧二铜(II)配合物引起的。四氮杂大环在层状结构中的各向异性堆积导致这些铜配合物具有异常的反应活性。我们首次表明，二氧化硅基质中铜配合物的有机-无机环境完全模拟了金属酶中蛋白质的保护作用。首次可以在室温下以稳定的形式分离出氧化的二铜(II)配合物，并且在几个吸附-解吸循环后可以再生还原的Cu(2)(I,I)物种。这些数据还表明，固体中环四胺铜的配位方案和反应活性与溶液中观察到的有很大不同。
