Theoretical and Experimental Insights into the Self-Assembly and Ion Response Mechanisms of Tripodal Quinolinamido-Based Supramolecular Organogels

The exploration and understanding of self-assembly and stimuli-responsive mechanisms of supramolecular systems are of fundamental importance for researchers to plan syntheses reasonably. Herein, the self-assembly and ions responsive mechanisms of a tripodal quinolinamido-based supramolecular organogel (TBT-gel) were investigated through experiments and theoretical calculations including independent gradient model (IGM), localized orbitals locator (LOL) and hole-electron theory. According to these studies, the self-assembly mechanism of TBT-gel was based on strong threefold H-bonding and pi-pi interactions, which induced the TBT forming helical, one-dimensional supramolecular polymer. After addition of Fe3+ into the TBT-gel, the one-dimensional supramolecular polymer had been crosslinked by the Fe3+ through coordination interaction and formed a metallogel (TBT-Fe-gel). Interestingly, the TBT-gel showed selective fluorescent response for Fe3+ and F- based on a competitive coordination mechanism. Moreover, the study on fluorescence responsive mechanism of TBT-gel for Fe3+ and F- implied the ICT mode governs both the electron excitation and de-excitation processes. The calculated results were in agreement with the corresponding experimental results. Notably, the quantum chemical calculations provided a deep understanding and visualized presentation of the assembly and stimuli-responsive mechanisms.

Automated summary

The self-assembly and stimuli-response mechanisms of the TBT-gel were investigated, revealing that it is based on strong hydrogen bonding, pi-pi interactions, and coordination interactions with Fe3+. The TBT-gel exhibited selective fluorescent response for Fe3+ and F- based on competitive coordination mechanisms, and the fluorescence response mechanism was governed by the ICT mode. The quantum chemical calculations provided a deep understanding and visualization of the assembly and stimuli-responsive mechanisms.