A Donor–Acceptor [2]Catenane for Visible Light Photocatalysis

Abstract

Colored charge-transfer complexes can be formed by the association between electron-rich donor and electron-deficient acceptor molecules, bringing about the narrowing of HOMO−LUMO energy gaps so that they become capable of harnessing visible light. In an effort to facilitate the use of these widespread, but nonetheless weak, interactions for visible light photocatalysis, it is important to render the interactions strong and robust. Herein, we employ a well-known donor−acceptor [2]catenaneformed by the mechanical interlocking of cyclobis(paraquat-p-phenylene) and 1,5-dinaphtho [38]crown-10in which the charge-transfer interactions between two 4,4′-bipyridinium and two 1,5dioxynaphthalene units are enhanced by mechanical bonding, leading to increased absorption of visible light, even at low concentrations in solution. As a result, since this [2]catenane can generate persistent bipyridinium radical cations under continuous visiblelight irradiation without the need for additional photosensitizers, it can display good catalytic activity in both photo-reductions and -oxidations, as demonstrated by hydrogen productionin the presence of platinum nanoparticlesand aerobic oxidation of organic sulfides, such as L-methionine, respectively. This research, which highlights the usefulness of nanoconfinement present in mechanically interlocked molecules for the reinforcement of weak interactions, can not only expand the potential of charge-transfer interactions in solar energy conversion and synthetic photocatalysis but also open up new possibilities for the development of active artificial molecular shuttles, switches, and machines.

Distinctive features and challenges in catenane chemistry

“…19a ). 90 Our group has reported the use of a catenane-coordinated copper( i ) for catalytic C–O cross-coupling reactions. 91 The copper is kinetically stabilised by the catenane ligands with a coordinatively saturated resting state, but the coordination sphere can also be accessed by the substrates due to the dynamic co-conformation changes of the catenane ligands.…”

Systems chemistry of peptide-assemblies for biochemical transformations

“…Self-assembly of molecules has long been studied for developing new emerging properties. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Efforts have been directed in recent years, illustrating the functions of advanced enzymes by various supramolecular structures based on amino acids, lipids and nucleic acids. [45][46][47] The successful utilization of self-assembled nano and microreactors has been shown to generate catalytic sites that promote an impressive set of advanced biochemical transformations.…”

Mechanical Interlocking Enhances the Electrocatalytic Oxygen Reduction Activity and Selectivity of Molecular Copper Complexes

“…These favorable features concerning the kinetic aspect of catalysis thus pave the way to the development of mechanical interlocking as a new paradigm in designing transition metal catalysts. In fact, catenanes are promising scaffolds for catalyst developments, [42][43][44] and other aspects of MIMs such as large-amplitude co-conformational change and mechanostereochemistry have been exploited in switchable and stereoselective catalysis as well. [45][46][47][48] kinetic features of peptide backbones in enzymes (see SI Section 1).…”