Stimuli-Responsive Reversible Fluorescence Switching in a Crystalline Donor-Acceptor Mixture Film: Mixed Stack
Sang Kyu Park1, Illhun Cho1, Johannes Gierschner2
1Center for Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, ENG 445, Seoul 151-744 (Korea).
Abstract:
We report on a molecularly tailored 1:1 donor-acceptor (D-A) charge-transfer (CT) cocrystal that manifests strongly red-shifted CT luminescence characteristics, as well as noteworthy reconfigurable self-assembling behaviors. A loosely packed molecular organization is obtained as a consequence of the noncentrosymmetric chemical structure of molecule A1, which gives rise to considerable free volume and weak intermolecular interactions. The stacking features of the CT complex result in an external stimuli-responsive molecular stacking reorganization between the mixed and demixed phases of the D-A pair. Accordingly, high-contrast fluorescence switching (red↔blue) is realized on the basis of the strong alternation of the electronic properties between the mixed and demixed phases. A combination of structural, spectroscopic, and computational studies reveal the underlying mechanism of this stimuli-responsive behavior.
