Highly stable tetrathiafulvalene radical dimers in [3]catenanes.

Two [3]catenane 'molecular flasks' have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, enabling their spectrophotometric and structural properties to be probed in detail. The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for the encircled TTF units to form stable dimers associated with their discrete oxidation states. These dimerization events represent an affinity umpolung, wherein the inversion in electronic affinity replaces the traditional TTF-bipyridinium interaction, which is over-ridden by stabilizing mixed-valence (TTF)2•+ and radical-cation (TTF•+)2 states inside the 'molecular flasks.' The experimental data, collected in the solid state as well as in solution under ambient conditions, together with supporting quantum mechanical calculations, are consistent with the formation of stabilized paramagnetic mixed-valence dimers, and then diamagnetic radical-cation dimers following subsequent one-electron oxidations of the [3]catenanes.

Model systems for flavoenzyme activity: an investigation of the role functionality attached to the C(7) position of the flavin unit has on redox and molecular recognition properties.

We describe the role functionality attached to the C(7) position of a family of flavin derivatives has in tuning their redox and recognition properties and the subsequent exploitation of two of these derivatives as a three-component electrochemically controllable molecular switch.

Tuneable side-chain supramolecular polymer.

[reaction: see text] A random copolymer containing 1,5-dialkyloxynaphthalene moieties has been synthesized using atom-transfer radical polymerization. We have shown that this polymer has the ability to form complexes with the tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)) and that electrochemical reduction of the cyclophane or the addition of a competing guest for the cavity of the cyclophane results in disassembly of the supramolecular polymer.

The tuneable complexation of gold nanoparticles.

Mixed monolayer protected gold nanoparticles have been fabricated incorporating 1,5-dialkyloxynaphthalene moieties that are capable of forming complexes with the tetracationic cyclophane cyclobis(paraquat-p-phenylene); electrochemical reduction of the cyclophane or the addition of tetrathiafulvalene results in disassembly of the complexes.

A tuneable self-complexing molecular switch.

[reaction: see text] A new self-complexing donor-acceptor system has been synthesized that has the propensity to undergo intramolecular decomplexation under thermal and electrochemical perturbation and upon addition of a competitive guest for the cyclophane's cavity.