Substituent effect on emission of flavonolate-boron difluoride complexes: The role of π-system for dual-state (solution and solid) emission

Dual-State Emission (DSE) in Organic Fluorophores: Design and Applications

“…Although for compounds 42a and 42b modest quantum yields of Φ F = 2.0%−5.2% in solution and Φ F = 21.0%−39% in the solid state were measured, 144,145 better results were observed for flavonolate-boron difluoride derivatives (43a−43d) with quantum yields ranging from Φ F = 13% to Φ F = 86% in solution and Φ F = 2% to Φ F = 45% in the solid state (Figure 19). 146 The D−A complexes 44a−44d (Scheme 9) reported by Chujo and co-workers also display DSE properties with quantum yields ranging from Φ F = 17% to Φ F = 80% in solution and Φ F = 25% to Φ F = 81% in the solid state. 147 In this category, Okamoto and co-workers reported a methodology to prepare a family of N,O-coordinated BF 2 complexes (45a−45g) with head-to-tail stackings as the primary arrangements observed on their X-ray structures.…”

“…Molecular structures and photographs under UV lamp in solution and in the solid state of flavonolate–boron difluoride derivatives ( 43a – 43d ). Reprinted with permission from ref . Copyright 2021 Elsevier.…”

D–A–D structured triphenylamine fluorophore with bright dual-state emission for reversible mechanofluorochromism and trace water detection

“…Recently, there is growing interest in developing dual-state emission (DSE) materials that show strong fluorescence in both dilute solutions and the solid state (nanoparticles, solid powders, crystals, and thin film), to bridge the gap between ACQ and AIE materials. [20][21][22][23][24][25][26][27][28] Nevertheless, available DSE materials are still very rare, and the design principle is not well understood. An understanding of the synthesis and the working mechanisms of new DSE materials is essential to facilitate widespread applications.…”

Alkyl-Engineered Dual-State Luminogens with Pronounced Odd–Even Effects: Quantum Yields with up to 48% Difference and Crystallochromy with up to 22 nm Difference

“…On the other side, the development of OLMs has enabled wide applications in sensors, bioimaging, electronics, and smart devices. − Among the OLMs, dual-state luminogens (DSEgens) have been of particular interest in recent years as these materials can luminesce in both dilute solutions and the solid state . It is understood that conventional aggregation-caused quenching luminogens which only luminesce in dilute solutions or the trending aggregation-induced emission luminogens which only luminesce in the aggregated state are usually employed in their respective emissive state, namely, dilute solutions or aggregates. − In contrast, DSEgens are demonstrated to be applicable in both a molecularly dispersed state and an aggregated/solid state attributed to their DSE features. , It is clear that the emission intensity is a crucial property of a DSEgen. To obtain DSEgens with bright emission, molecules are often engineered into an extended π system with sufficient electron transfer. − Aryl units, especially those with electron-donating and electron-withdrawing properties, are often employed to tune the photophysical properties. ,− By contrast, the use of the alkyl chain receives much less attention due to its low electronic effect.…”

“…19−22 In contrast, DSEgens are demonstrated to be applicable in both a molecularly dispersed state and an aggregated/solid state attributed to their DSE features. 23,24 It is clear that the emission intensity is a crucial property of a DSEgen. To obtain DSEgens with bright emission, molecules are often engineered into an extended π system with sufficient electron transfer.…”