We report on the fluorescence properties of a new class of emissive and stable π-radicals that contain a boron atom at a position distant from the radical center. A fully planarized derivative exhibited an intense red fluorescence with high fluorescence quantum yields (Φ F > 0.67) even in polar solvents. To elucidate the origin of this phenomenon, we synthesized another boron-stabilized radical that contains a bulky aryl group on the boron atom. A comparison of these derivatives, as well as with conventional donor-π-acceptor (D-π-A)-type emissive π-radicals, unveiled several characteristic features in their photophysical properties. A theoretical analysis revealed that the SOMO-LUMO electronic transition generates an emissive D 1 state. Unlike conventional D-π-A-type π-radicals, this state does not undergo significant structural relaxation. The boronstabilized π-radicals demonstrated promising potential for organic light-emitting diodes as an emitting material.

Tricoordinate boron imparts near-infrared absorption/emission and unusual multi-stage changes in the photophysical properties to fluorescein dyes.

We report on the fluorescence properties of a new class of emissive and stable π‐radicals that contain a boron atom at a position distant from the radical center. A fully planarized derivative exhibited an intense red fluorescence with high fluorescence quantum yields (ΦF >0.67) even in polar solvents. To elucidate the origin of this phenomenon, we synthesized another boron‐stabilized radical that contains a bulky aryl group on the boron atom. A comparison of these derivatives, as well as with conventional donor–π–acceptor (D–π–A)‐type emissive π‐radicals, unveiled several characteristic features in their photophysical properties. A theoretical analysis revealed that the SOMO–LUMO electronic transition generates an emissive D1 state. Unlike conventional D–π–A‐type π‐radicals, this state does not undergo significant structural relaxation. The boron‐stabilized π‐radicals demonstrated promising potential for organic light‐emitting diodes as an emitting material.

In biosynthesis multiple kinds of reactive intermediates are generated, transported, and reacted across different parts of organisms, enabling highly sophisticated synthetic reactions. Inspired by such ideal reaction conditions, herein we report a convergent synthetic approach using double intermediates, carbocations and carbanions, at once. By reactions of unsaturated precursors, such as enamines, with a superacid in a flow microreactor, carbocations were generated rapidly and irreversibly, and before decomposition, they were transported to react with rapidly and independently generated carbanions, enabling direct C–C bond formation. Taking advantage of the reactivity of these double reactive intermediates, the reaction took place within a few seconds, enabling synthetic reactions which are not applicable in conventional reactions.

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