Light controlled oxidation by supramolecular Zn(ii) Schiff-base complexes

Abstract

The application of supramolecular host–guest chemistry for controlled photoreactivity and molecular sensing is a highly important field of modern inorganic and physical chemistry. One key aspect is the formation of the triplet state after photoexcitation. Applications of zinc ion Schiff-base derivatives for this purpose are rarely reported in the literature and there is still a lack of investigation into the triplet state formation of these supramolecular complexes. In this paper, triplet state formation and photosensitization is demonstrated for Zn(II) salicylaldiminato-functionalized calixarene complexes. We show that the photoinduced triplet state formation and the photoreactivity is a direct consequence of the Zn²⁺ complexation. Herein, the photochemical reactivity, as well as the mechanistic details of the photooxidation were deduced from a comprehensive set of steady state and time resolved spectroscopic as well as radiation chemistry data, respectively. The metal center (Zn²⁺) controlled photoreactivity observed here may lead to novel applications in the direction of photodynamical therapy or may open new avenues in catalysis, selective reactions and sensor applications.