Modifying the reactivity of substrates by encapsulation is a fundamental principle of capsule catalysis. Here we show an alternative strategy, wherein catalytic activation of otherwise inactive quinone "co-factors" by a simple Pd 2 L 4 capsule promotes a range of bulk-phase, radical-cation cycloadditions. Solution electron-transfer experiments and cyclic voltammetry show that the cage anodically shifts the redox potential of the encapsulated quinone by a significant 1 V. Moreover, the capsule also protects the reduced semiquinone from protonation, thus transforming the role of quinones from stoichiometric oxidants into catalytic single-electron acceptors. We envisage that the host−guest-induced release of an "electron hole" will translate to various forms of non-encapsulated catalysis that involve other difficult-to-handle, highly reactive species.

External effector binding allosterically regulates the catalytic properties of a simple Pd2L4 capsule.

The syntheses of two novel mechanically chiral rotaxanes containing urea and squaramide motifs (in yields of 33 % and 22 %, respectively) are presented. 1 H NMR spectroscopic titrations reveal shuttling of the macrocycle -detect-able by modulation of the expression of mechanical chirality in the NMR spectrum -is possible through the addition of achiral chloride anions, a process which is reversed by the addition of sodium cations.

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Coordination cages have emerged as an interesting and diverse subset of supramolecular systems that utilise the assembly of ligands and metals to create constructs with hollow interiors. This inner space provides opportunities for many applications; however, exploiting it for catalysis is arguably the most interesting and challenging of academic pursuits. In this chapter, we will outline how coordination cage catalysis emerged and followed on from earlier examples of supramolecular methods and highlight the remarkable progress that has been made in the past two decades. This chapter is not intended as a comprehensive review; rather it has been limited to select examples that serve to represent both what has been achieved and what is the current state of the art.