Variations in the fuel structure control the rate of the back and forth motions of a chemically fuelled molecular switch.

This work deals with the use of 2-cyano-2-arylpropanoic acids as chemical fuels for an acid-base operated molecular switch that consists of a Sauvage-type catenand composed of two identical macrocycles incorporating a phenanthroline unit. When used as a base promoter of the decarboxylation of propanoic acid derivatives, the switch undergoes large amplitude motion from the neutral catenand to a protonated catenate and back again to the neutral state. The rate of back proton transfer, which determines the rate of the overall process, was markedly affected by -substituents in the order Cl > H > CH > OCH ( = +5.

Formation of Imidazo[1,5-a]pyridine Derivatives Due to the Action of Fe on Dynamic Libraries of Imines.

An imidazo[1,5-a]pyridine derivative was unexpectedly obtained through the action of Fe on a dynamic library of imines generated in situ via condensation of benzaldehyde and 2-picolylamine. The reaction product was easily isolated as the only nitrogen-containing product eluted from the chromatographic column. A reaction mechanism is proposed, in which combined kinetic and thermodynamic effects exerted by Fe on the various steps of the complex reaction sequence are discussed.