Rational Control of Charge Transfer Excitons Toward High‐Contrast Reversible Mechanoresponsive Luminescent Switching

Abstract

A practicable strategy to rationally obtain the reversible mechanochromic luminescent (MCL) material with high‐contrast ratio (green versus red) has been established. By introducing a volatile third party (small‐sized solvent molecules) into the lattice of charge transfer (CT) cocrystal of mixed‐stacking 1:1 coronene (Cor.) and napthalenetetracarboxylic diimide (NDI), a noteworthy reconfigurable molecular assembly is ingeniously achieved owing to the loosely packing arrangement as well as weakened intermolecular interactions. Accordingly, the CT excited state, strongly corresponding to the molecular stacking modes, can be intentionally tailored through external stimulus (heating, grinding, or solvent), accompanying distinct changes in photophysical properties. Subsequently, a high‐contrast reversible MCL with highly sensitive and good reproducibility is realized and the underlying mechanism is thoroughly revealed.

Full‐Color Emissive D‐D‐A Carbazole Luminophores: Red‐to‐NIR Mechano‐fluorochromism, Aggregation‐Induced Near‐Infrared Emission, and Application in Photodynamic Therapy

“…[4] On the other hand, to prepare highly-efficient mechano-luminochromic materials, noteworthy aggregativestate emission and high color contrast (especially for Δλ em,max > 100 nm) before and after exposing to mechanical stimuli are considered as two essential factors. [5] The light emissions in the solution state of numerous conventional luminogenic molecules are partially or completely quenched upon aggregation due to the ubiquitous aggregation-caused quenching (ACQ) effect, which is a thorny obstacle for high-tech applications of mechanical force-responsive luminescence materials and biological applications of emissive materials. [6] Fortunately, in 2001, an interesting phenomenon of aggregation-induced emission (AIE) was observed by Tang et al [7] Next, in 2002, Park et al described an "aggregation-induced emission enhancement" (AIEE) effect caused by intramolecular planarization and J-type aggregate formation.…”

Tuning Solid-State Emission of 9-Anthraldehyde through Cocrystal Engineering

“…Charge-transfer (CT) cocrystals, in particular, often exhibit unique physicochemical properties [23][24][25][26][27][28]. Lei et al, designed a hybrid CT heterogeneous microtubule with efficient white light emission [29], which is a promising development.…”

Optical and electrical modulation in ultraviolet photodetectors based on organic one‐dimensional photochromic arrays

“…Stimuli‐responsive materials are of particular interest due to their tunable and reversible physicochemical characteristics under external stimuli, such as pH, 1,2 temperature, 3,4 electricity, 5,6 or light 7–9 . Among them, light is an attractive stimulus for constructing functional devices because of its spatiotemporal controllability.…”