The kinetics of an alkylation reaction are used to probe the effect of an electron-withdrawing pyridinium group on the nucleophilicity of a free pyridine in a photoresponsive dithienylcyclopentene (DTCP) derivative in order to demonstrate effective and reversible control over chemical reactivity. The kinetic data support the hypothesis that the ring-open isomer of the DTCP (1o) is more reactive than its ring-closed counterpart (1c) due to ...
