Molecular Aggregation to and from Disaggregation of an Organic Emitter for Strategic Emission Modulation

“Aggregation‐caused fluorescence quenching” is a well‐established phenomenon by now. The procedure from aggregation to disaggregation usually causes a revival of emission signals, and thus affords an interesting new path to design “turn‐on” optical probes. For this purpose, the photophysics, energetics and dynamics of supra‐molecular encapsulation induced disaggregation of a self‐assembled bis‐indole derivative, 3,3’‐bisindolyl(phenyl)methane (BIPM), and its further reaggregation are reported herein. Compared to disaggregation strategies, its reverse process, reaggregation, has received much less attention so far. The gamma‐cyclodextrin (γ‐CD) molecules were found to be effective in disaggregating the BIPM associations and emission enhancement, whereas, the incorporation of guanidine hydrochloride (Gnd‐HCl) into the aqueous solution of disaggregated BIPM monomers in γ‐CD environment resulted in probe reaggregation leading to quenching of the restored emission. Here, γ‐CD and Gnd‐HCl can be considered as the molecular modulators of BIPM fluorescence based on the disaggregation–reaggregation mechanisms. The spectroscopic and thermodynamic findings associated with the disaggregation‐reaggregation processes might be insightful in reversible controlling of molecular aggregation and the associated optical properties for diverse applications.