Intra-supramolecular photoinduced electron transfer in redox-active coordination cages
Marcel Krick, TU Dortmund, Dortmund, GermanyMarina Frank, Georg August Universität Göttingen, Göttingen, GermanyJennifer Ahrens, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, GermanyDirk Schwarzer, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, GermanySusanne Löffler, TU Dortmund, Dortmund, GermanyGuido H. Clever, TU Dortmund, Dortmund, Germany
Supramolecular self-assembly is a comfortable way to form complex chemical structures and materials with unique features, starting from easily synthesised building blocks. In the last years, supramolecular cages with promising properties, such as selective recognition, storage, transport of guest molecules or function as molecular reaction flasks attracted attention in this area of research and beyond. Based on bis-monodendate pyridyl ligands, we reported the synthesis and characterization of new interpenetrated coordination cages [Pd4L8] which were found to be strong receptors for halide anions. Additionally, we realized a stimuli-responsive system for the sequential uptake of different guest molecules.
Recently, we extended our work to the implementation of redox functionality and synthesized selfassembled cages consisting of electron-rich phenothiazine ligands. The latter compound is part of some well established systems for photoinduced electron transfer applications, often in combination with electron-poor anthraquinones. In a mixed donor-acceptor-functionalized supramolecular system, we now could observe an intra-supramolecular photoinduced electron transfer between self-assembled ligands with the help of femtosecond pump-pulse experiments. Gaining control over the morphology of the photoactive layer with respect to the intermolecular contacts between the donor, acceptor and electrode materials is a major challenge in the construction of efficient photovoltaic devices. The supramolecular assembly approach shown herein has potential for the development of novel materials for photoactive layers with controlled morphology in future photovoltaic devices.
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