Achieve Full‐Color Emission in Multiple States through Reversible B←N Bond Formation and Multiple Configuration Transitions of a Single Fluorophore

Abstract Multifunctional molecular switches have attracted much attention because of their unique stimulus response behavior and advanced applications. However, precise regulation of the structure for property enrichment is still a great challenge. Herein, the first case of a single‐molecule switch BN‐S with multiple structurally tunable and full‐color fluorescent properties is reported. Interestingly, BN‐S exhibits a butterfly‐like “metamorphosis” crystal growth process accompanied by full‐color fluorescence emission (including white light, CIE = 0.33, 0.33; 456 nm → 610 nm). It is shown that this is related to the reversible B←N bonding and the tunability of the spatial structure of the BN‐S. Thus, BN‐S exhibits superior multicolor tunability in different states (solid, liquid, and film), and its applications in white‐light optical light emitting diodes (OLEDs) and multicolor fluorescent inks also show great promise. This will provide a new strategy for designing and synthesizing the development of multifunctional molecular switching materials and enriching the variety of organoboron luminescent materials.