Magic-Angle\nExciton Coupling in a Molecular Solid:\nOptical Consequence of Null–Coulombic Coupling

Instances of magic angle excitonic coupling and its optical\nconsequences\nare infrequently documented in the literature, yet they hold fundamental\nsignificance in understanding excited state electronic processes within\nmolecular aggregates. Weak/null long-range dipolar Coulombic coupling\nis the characteristic of chromophore arrays positioned in a magic\nangle configuration. This study presents a rare example of such phenomena\nin CF<sub>3</sub>DPT solids, resulting in a high fluorescence quantum\nefficiency of 62 ± 3% in the aggregated solid state. Supported\nby computational calculations, we validate our experimental findings\nof null–Coulombic coupling and significant charge transfer\n(CT) coupling within the solid state.