Piezochromic Luminescence of Cyano Substituted E/Z Isomeric Derivatives: Different Responses to External Stimuli

Abstract

As an important class of stimuli‐responsive material, piezochromic organic materials have been widely investigated in recent years. To promote their further applications as pressure sensors, realizing a high sensitivity and big color contrast, especially under high external pressure, is of great importance. Herein, two pure cis/trans isomers, E‐ANTCN and Z‐ANTCN, based on anthracene and cyano substituted double bond are achieved. The molecular structures are determined by nuclear Overhauser effect spectroscopy, correlation spectroscopy, and X‐ray diffraction. At ambient conditions, both of them show typical mechanochromic characteristics under grinding−heating or grinding−fuming treatments. E‐ANTCN displays a sensitivity of 0.83 nm GPa−1 and a color contrast of 5 nm in a high‐pressure experiment, while Z‐ANTCN shows a much enhanced sensitivity of 22.64 nm GPa−1 and bigger color contrast of 110 nm, indicating the potential as a good colorimetric sensor for external pressure. The two cyano groups in the same side of double bond in Z‐ANTCN induce more intense intermolecular interactions with a resultant spatial packing mode being mainly responsive for its good sensing performance. This study fills the gap for a piezochromic property and high‐pressure experiment of E/Z isomers and provides useful information for the investigation of molecular structural changes under isotropic and anisotropic treatments.

Modulating the electron-donating ability of aggregation-induced emission molecules for improved photo-responsive properties

“…These results indicate that compound DOPBYN possesses both photoisomerization and photodimerization photoreactions by simple molecular structure regulation, which is a multifunctional photo-responsive molecule compared with other materials comprising the cyanostilbene unit (Table S4, ESI†). 42–45…”

“…These results indicate that compound DOP-BYN possesses both photoisomerization and photodimerization photoreactions by simple molecular structure regulation, which is a multifunctional photo-responsive molecule compared with other materials comprising the cyanostilbene unit (Table S4, ESI †). [42][43][44][45] The distinct photo-triggered fluorescence turn-off behaviors along with the photodimerization process are valuable for information encryption. As depicted in Fig.…”

“…Stimulation-responsive materials whose photophysical properties including absorption and emission can be regulated and controlled upon exposure to external stimuli, including light irradiation, pressure, temperature, electricity, and magnetism, have been widely used in the fields of data storage, optoelectronic devices, and information security. [1][2][3][4][5][6][7] Among these various stimuli sources, light is recognized as a fascinating type because of its variable emission wavelength, intensity, and noninvasive control. The favorable merits render the photoresponsive materials with special attention from researchers.…”

Near‐infrared Piezochromic Materials at High Pressure

“…That is to say, increasing π-π interactions due to the overlapping of anthracene planes intensify excitonic coupling and orbital overlap between neighboring molecules (Figure 3b). Lu et al [29] have reported in 2022 an E/Z isomerism of cyanostilbene derivatives Bis(anthracen-9-yl)phenyl)fumaronitrile (E-ANTCN/Z-ANTCN, Figue 2). Different conformations induce degrees of excited state charge transfer and spatial stacking patterns.…”

Recent Advances in Mechano-responsive Fluorescent Organic and Organometallic Compounds: Structural Diversity, Phase Transformation and Applications

“…In addition, two E/Z isomers of anthracene and cyano-substituted ethylenes (5E and 5Z ; see the structures of these compounds in Table 1) were synthesized. [89] Upon grinding, both compounds exhibited mechanochromic characteristics. The results of powder X-ray diffractometry (PXRD) investigations indicated that, after grinding treatments, the crystals were almost entirely converted into amorphous solids.…”