pH‐Controlled Transition from Disaggregation to Reaggregation of Bis‐indolyl(phenyl)methane−β‐CD Conjugate Appended with Multi‐logic Operations

Abstract A multifunctional molecular logic system is designed based on the pH‐responsive emission properties of bis‐indolyl(phenyl)methane (BIPM)−β‐CD conjugates in aqueous medium. In our previous studies, BIPM molecules in water were found to form large molecular self‐aggregates that disaggregated in presence of β‐CD molecules through inclusion complexation. In the present study, transition from the disaggregated to reaggregated form of bis‐indolyl(phenyl)methane−β‐CD conjugate was followed through alteration of the local pH from 7 to 13.2. The BIPM molecules are expected to reaggregate at high alkaline medium due to the expulsion of probes from the nano‐cages of β‐CD. The pH dependent emission spectroscopic changes are harvested to design a multi‐functional molecular logic system that can mimic the functions of several fundamental logic gates and an ‘erase‐read‐write‐read’ memory unit. A macro‐molecular security system with three chemical inputs is also presented that can authenticate all‐active‐all‐possible (3³) three‐character passwords with their respective unique fluorescence trajectories. Designing of molecular logic system based on the pH‐responsive emission properties of the aggregated and disaggregated forms of an organic probe is rather uncommon and the multifunctional logic, memory and security applications of the present system will carry significant importance in the molecular logic research.