The application of cis-[Ru"(bpy),(L 1 )(L2)]2' for the photo-triggered release of the molecules L 1 IL2 is weil known in the literature. The photoactive MLCT band of these complexes lies in the visible region. Consequently, the ligands can be released by using light with a wavelength of 400 nm and above.I1I
This strategy was transferred to polymeric structures in order to design novel materials which are degradable via visible and NIR light. In one material, the ruthenium complex cis-[Ru11(bpy),(4AMP),]2 (with 4AMP = 4-aminomethylpyridine) was incorporated into polyureas to form hydrogels.121 In ' another material, cis-[Ru11 3(bpy),Cl,]2' was used to cross-link commercially available poly(4-vinylpyridine) also yielding a ge1.1 1 In both cases, upon irradiation with visible light
the pyridine moiety dissociates rapidly due to a cleavage of the Ru-N band which leads to degradation of the gels. The photocleavage only occurs in directly irradiated regions and enables a spatial control of the degradation. This allows for micro-patterning in multi-photon processes in the NIR. For the gels obtained from poly(4-vinylpyridine) the degradation is reversible as was demonstrated by writing, erasing, re-writing cycles.
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Englisch
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Hauptvortrag / Eingeladener Vortrag auf einer Tagung