Tuning Solid-State Emissions via Twists and Turns in Polymorphic Self- and Cross-Coupled Dianthrylethenes

Abstract

Tuning solid-state fluorescence in organic materials enriches the fundamentals and practical utilities in the emerging field of optical technology. This report details the innovative synthesis of dianthrylethenes linked to pentylphenylaminophenyl (C5DPA) and 1,4-dimethoxyphenyl (1,4-DMP) as rotors, yielding vibrant, multicolor, highly intense solid-state emitters. Not only typically observed symmetrically substituted olefins, but a classic oxidative dephosphorylation reaction is also introduced herein to conveniently access both unsymmetrically and symmetrically substituted olefins from the one-pot reaction. The flexible C5DPA induces polymorphism in DPAn2, which fluoresces in distinct wavelengths from three discrete molecular packings, and is observed in DPAn2-G, DPAn2-Y, and DPAn2-O crystals. Contrarily, 1,4-DMP-linked rigid analog DMAn2 does not exhibit such variation. Fluorescence switching among polymorphs is achieved upon applying mechanical and thermal stimuli that slide crystal planes and twist/bend anthryl units. The single crystals of the twisted/bent structures elucidate fluorescence switching behavior by varying the supramolecular architecture. Deformation in anthryl core for this new class of olefins controlling the solid-state emission is unique and recognized herein for the first time. The crossed-coupled olefin DPDM is introduced to establish structure-property relationships. This one-pot oxidative dephosphorylation strategy paves the way for designing diverse olefinic luminescent materials, displaying polymorphism-driven structural changes and tailoring the solid-state optical properties.