Achieving In Situ Dynamic Fluorescence in the Solid State through Synergizing Cavities of Macrocycle and Channels of Framework

Abstract

To achieve in situ dynamic fluorescence in the solid state and unveil the mechanism remain a formidable challenge. Herein, through synergizing the cavities of macrocycles for dynamic complexing and the channels of frameworks for facile transit, we construct intrinsic channels from an emissive cyclophane and realize precisely tunable emission in the solid state through the sequential guests’ exchange. Specifically, two design criteria involve (1) The twisted cyanostilbene units not only endow the systems with solid-state fluorescence but also tailor the π–π interactions in the complex to generate the desired emission and (2) the large cavity of cyclophane results in the formation of ternary complexes with controllable binding affinity which further assemble into robust channels for the guests’ exchange in the bulky state. This strategy unifies the advantages of both macrocycle and framework in one system, achieving visualization, recyclability, and easy processability simultaneously. The present study paves an easy, efficient, and general platform for constructing dynamic optical materials.

Recent advances in tunable solid-state emission based on α-cyanodiarylethenes: from molecular packing regulation to functional development

“…Notably, complexation forms include guests (single molecule or dimers) within or between hosts. 42,43 (3) Porous molecular crystals formed by CAE self-assembly respond to included guests. 44 These crafted assemblies possess well-defined molecular entities, rendering them ideal platforms for elucidating the interplay between intermolecular electronic energy transfer and photophysical properties.…”

“…12(c)). 42 Cocrystallization of the compound with benzene ( Ben ) resulted in a channel structure built by the macrocycle that capable of accommodating benzene molecules. Subsequently, we selected to exchange the guest molecules with toluene ( Tol ), thiophene ( Thi ), naphthalene ( Nap ), and pyrene ( Py ) via diffusion.…”

Construction of 1,3,5-Triazine-Based Prisms and Their Enhanced Solid-State Emissions

“…The stacking pattern of molecules is one of the most important factors affecting the optical behavior of molecules. The strategies, including cocrystal, host–guest interaction, and steric hindrance, were employed to enhance solid-state emission by controlling of molecular packing . In this regard, 1,3,5-triazine motifs with good thermal stability and electrophilic properties − are often used as acceptor units in phosphor emitters, − organic light-emitting diodes (OLED), , and fluorescence sensing. − However, owing to the high planarity of the triazine ring, fluorescence is severely quenched in the solid state because of strong π–π stacking interactions, which considerably affects the luminescent properties of the materials.…”

“…The stacking pattern of molecules is one of the most important factors affecting the optical behavior of molecules. The strategies, including cocrystal, 39 host−guest interaction, 40 and steric hindrance, 41 were employed to enhance solid-state emission by controlling of molecular packing. 42 In this regard, 1,3,5-triazine motifs with good thermal stability and electrophilic properties 43−45 are often used as acceptor units in phosphor emitters, 45−47 organic lightemitting diodes (OLED), 48,49 and fluorescence sensing.…”