Structural Engineering of Luminogens with High Emission Efficiency Both in Solution and in the Solid State

Abstract

Developing molecules with high emission efficiency both in solution and the solid state is still a great challenge, since most organic luminogens are either aggregation‐caused quenching or aggregation‐induced emission molecules. This dilemma was overcome by integrating planar and distorted structures with long alkyl side chains to achieve DAπAD type emitters. A linear diphenyl–diacetylene core and the charge transfer effect ensure considerable planarity of these molecules in the excited state, allowing strong emission in dilute solution (quantum yield up to 98.2 %). On the other hand, intermolecular interactions of two distorted cyanostilbene units restrict molecular vibration and rotation, and long alkyl chains reduce the quenching effect of the π–π stacking to the excimer, eventually leading to strong emission in the solid state (quantum yield up to 60.7 %).

Integrating Time‐Resolved Imaging Information by Single‐Luminophore Dual Thermally Activated Delayed Fluorescence

“…Such an alternation of the intensity of the two bands leads to as trong transfer of luminescence color (white-blue-green) observed by the naked eye (Figure 3d;C IE diagram in Figure S11). According to literature data, [19] this phenomenon reflects ac hange of the molecular aggregation states,t he process of which can be monitored by ad ynamic light scattering experiment (DLS, Figure S12). Naturally,there are still prompt fluorescence and delayed fluorescence components in the dual emission of the aggregated state (Fig-ures S13-S15).…”

Dual‐Phase Thermally Activated Delayed Fluorescence Luminogens: A Material for Time‐Resolved Imaging Independent of Probe Pretreatment and Probe Concentration

“…However, these peaks disappeared in the XRD spectrum of the sample prepared from DMF with 95 % water, suggesting that the structure became more amorphous and lead to a CT nature made up of hydrogen bonding interactions in the aggregated state. It is known that the formation of π–π stacking in molecules can often deteriorate the emission in aggregated states by facilitating non‐radiative pathways . Therefore, we can conclude that the reduction of the emission with a red‐shift in our case originated from the π–π stacking between molecules, while the restoration of the emission with a blue‐shift upon a further molecular aggregation results from the intermolecular hydrogen bonding.…”

Dual‐Phase Thermally Activated Delayed Fluorescence Luminogens: A Material for Time‐Resolved Imaging Independent of Probe Pretreatment and Probe Concentration

“…However,these peaks disappeared in the XRD spectrum of the sample prepared from DMF with 95 %w ater, suggesting that the structure became more amorphous and lead to aCTnature made up of hydrogen bonding interactions in the aggregated state.I ti s known that the formation of p-p stacking in molecules can often deteriorate the emission in aggregated states by facilitating non-radiative pathways. [19] Therefore,w ec an conclude that the reduction of the emission with ar ed-shift in our case originated from the p-p stacking between molecules,w hile the restoration of the emission with ab lueshift upon af urther molecular aggregation results from the intermolecular hydrogen bonding.…”

“…Tr aditional luminescent probes generally require low concentrations to avoid aggregation for bioimaging, [19,21] because of their ACQe ffect. Nevertheless,incontrast, those AIE type probes need high concentrations to form aggregates for imaging.…”