High-contrast and reversible mechanochromic luminescence of a D–π–A compound with a twisted molecular conformation

Abstract

By integrating a triphenylamino donor (D) and a (2,2-dicyanovinyl)phenyl acceptor (A) with an anthryl π-spacer, a mechanochromic luminescent (ML) D-π-A compound, TPAANDCV, has been constructed. The single crystals of TPAANDCV display efficient green emission with a good fluorescence quantum yield (Ф F ) of 0.35. Upon grinding the crystals, a dramatic emission-colour variation from green to orange-red has been observed, and such a variation can be erased through annealing or solvent-vapour fuming. Moreover, the emission of the ground sample is also bright with a Ф F value of 0.11. The powder XRD measurements indicate that the emission-colour change upon grinding is caused by a partial conversion of the ordered solid-state structures to an amorphous state. The high-contrast and reversible fluorescent response of TPAANDCV towards mechanical stress, as well as the bright emission of both the unground and ground states, enable TPAANDCV to be a good ML material.

Dicyanomethylenated Acridone Based Crystals: Torsional Vibration Confinement Induced Emission with Supramolecular Structure Dependent and Stimuli Responsive Characteristics

“…The powder X-ray diffraction (PXRD) measurements (Figure ) revealed that the as-crystallized samples and vapor-fumed or heated solids have identical diffraction patterns, indicating that vapor or heating treatment results in the recovery of the original crystalline phases. On the other hand, the ground solids exhibit a few weak peaks or no diffraction peak, suggesting their amorphous or amorphous-like nature. − ,, These observations imply that the well-ordered crystalline states can be destroyed by mechanical force and be restored by thermal or organic vapor stimulus. Additionally, it was found that the DPA-DCNAC-C4 crystal was more sensitive to mechanical stimuli in the grinding process.…”

Multistimuli‐Responsive Materials from Benzothiadiazole‐Based Charge‐Transfer Chromophores: Interdependence of Optical Properties and Aggregation

“…The occurrence of metastable states that, subject to external stimuli, can interconvert or evolve towards the thermodynamically stable state, is a prerequisite for obtaining stimuli‐responsive materials . In this context, mechanochromic dyes, capable of changing their spectral properties when subject to mechanical stress, such as grinding, shearing and pressure, are particularly interesting .…”

Suitability of alkyne donor-π-donor-π-donor scaffolds for electrofluorochromic and electrochromic use

“…32 The length, and hence the type of p-linker, such as alkene and alkyne bridges, are useful handles to adjust the optical and emissive properties. [33][34][35][36][37][38] These properties can be further tuned by taking advantage of the latent reactivity of alkynes with activated methylenes to extend their functionalization via ''click-chemistry''.…”