Disaggregation-induced resurgence of quenched emission of a self-assembled bis-indole system: photophysics, energetics, and dynamics

Abstract

Disaggregation-induced emission enhancement was studied using a self-aggregated bis-indole derivative, 3,3′-bisindolyl(phenyl)methane (BIPM), and β-CD molecules were employed for the emission recovery. In our recent study, BIPM molecules were found to exhibit weak emission efficiency in pure water due to aggregation-caused quenching (ACQ) effects. In the present study, we employed a simple, effective, biologically benign, and sustainable strategy in an attempt to disaggregate the BIPM self-aggregates into monomers to restore their emission efficiency. The β-CD molecules were found to be effective in disaggregating the BIPM associations through tugging the monomers from their self-associations and encapsulating them into supramolecular nanocavities. The changes in the photophysical, dynamical, and thermodynamic properties associated with the disaggregation of the probe assemblies were studied by employing steady-state and time-resolved spectroscopy, isothermal titration calorimetry, and transmission electron microscopy with support from computational studies. The detailed photophysical and thermodynamic investigations on the disaggregation of the BIPM self-associations might provide significant insights towards its suitability for diverse biological and pharmaceutical applications.