Orthogonal Recognition Processes Drive the Assembly and Replication of a [2]Rotaxane

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.