Activating catalysts with mechanical force.

Homogeneously catalysed reactions can be 'switched on' by activating latent catalysts. Usually, activation is brought about by heat or an external chemical agent. However, activation of homogeneous catalysts with a mechanical trigger has not been demonstrated.

Highly efficient mechanochemical scission of silver-carbene coordination polymers.

The ultrasound-induced scission of silver carbene coordination complexes with polytetrahydrofuran-functionalized N-heterocyclic carbene ligands is reported. In solution, scission is very efficient, with complete conversion within 10 min when the polymers have a molecular weight of 6.7 kDa.

Template effect of tetrathiafulvalene in the formation of cyclobis(paraquat-p-phenylene).

[reaction: see text] The template effect exerted by tetrathiafulvalene (TTF) in the ring-closure reaction of the trication 5(3+) yielding cyclobis(paraquat-p-phenylene) has been quantitatively evaluated in acetonitrile at 62 degrees C with UV-vis spectrophotometry. The rate of ring closure of the trication 5(3+) largely increases in the presence of the template (a maximum increase of ca. 80 times at [TTF] approximately 0.

Catalysis in the self-assembly of [2]rotaxanes and [2]pseudorotaxanes. Effect of the length of polyethereal side arms and terminal stoppers.

The template effects exerted by compounds 3, 5, 6, and 8 in the ring closure reaction of the trication 1(3+) to yield the [2]pseudorotaxanes 15(4+) and 17(4+) and the [2]rotaxanes 18(4+) and 20(4+) have been quantitatively evaluated in acetonitrile at 62 degrees C by UV/vis spectrophotometry. The rate of ring closure of the trication 1(3+) largely increases in the presence of the templates up to a maximum of ca. 200 times in the case of 5 at a concentration of ca.