Construction of nonlinear response systems utilizing molecular machines

Construction of nonlinear response systems is of importance for switching and amplification of guest affinity and selectivity. In nature the phenomena are ubiquitous, however, the methodology for the design of such artificial systems has not been developed so far. In nonlinear response systems, the guest binding information must be efficiently transmitted to the other binding sites through the positive homotropic allosteric interaction. Here, we show a new concept utilizing a molecular machinery approach to realize the nonlinear response. In our scheme, rotating modules are used for the allosteric interaction, where the guest binding information in a binding site is passed to the other binding sites in unison through "rotation". With this concept, we rationally designed a variety of double decker porphyrin host molecules as well as the other host molecules bearing rotational axle. These studies open up a new field for designing intelligent molecular machinery systems which can respond to outer stimuli.