posted on 2015-12-30, 00:00authored byTamara Kosikova, Nurul
Izzaty Hassan, David B. Cordes, Alexandra M. Z. Slawin, Douglas Philp
Within a small, interconnected reaction
network, orthogonal recognition
processes drive the assembly and replication of a [2]rotaxane. Rotaxane
formation is governed by a central, hydrogen-bonding-mediated binding
equilibrium between a macrocycle and a linear component, which associate
to give a reactive pseudorotaxane. Both the pseudorotaxane
and the linear component undergo irreversible, recognition-mediated
1,3-dipolar cycloaddition reactions with a stoppering maleimide group,
forming rotaxane and thread, respectively. As a result of these orthogonal
recognition-mediated processes, the rotaxane and thread can act as
auto-catalytic templates for their own formation and also operate
as cross-catalytic templates for each other. However, the interplay
between the recognition and reaction processes in this reaction network
results in the formation of undesirable pseudorotaxane complexes,
causing thread formation to exceed rotaxane formation in the current
experimental system. Nevertheless, in the absence of competitive macrocycle-binding
sites, realization of a replicating network favoring formation of
rotaxane is possible.