Remote control supramolecular switch using ring-substituted peri-naphthoindigo derivative

Abstract

Unlike artificial self-assemblies, many biological systems often rely on indirect input for their adaptive structures and function. To reduce the stark differences with the natural counter part, artificial self-assemblies should also operate with the help of indirect input for adaptation. In this article we have emphasised the same using a new ring substituted peri-naphthoindigo (BuPNI) dye. The dye showed improved solubilty in non-polar solvents and different aggregation behaviour then the partent PNI. The new dye underwent self-assembly process in non-polar solvents (MCH, toluene), and the aggregation behaviour was tuned with the help of different guests like TFA, C60-fullerene and TfOH. By interacting with the donor-acceptor pairs of the dye, TFA changed the intermolecular arrangement. The rearrangment was found to be different when TfOH was used as guest. Similarly, C60-fullerene interacted with the aggregated dye and produced charge-transfer complex in the excited state. The guest-induced supramolecular rearrangement was also studied remotely by making change in an adjacent layer via diffusion method. Placing an acid-induced rearranged aggragate in an organic solvent over an aquesous solution allowed expulsion of the acid via diffusion, which in turn freed the chromophore and regenerated the original aggregate. Situation was reversed by the addition of the acid in the aqueous layer. Contrary to the typical processes of acid-induced supramolecular rearrangements, which were spectrocopically reversible but not chemically, our concept is fully reversible as it did not produce unwated waste (salt) in the reverse step