Structure‐Dependent cis/trans Isomerization of Tetraphenylethene Derivatives: Consequences for Aggregation‐Induced Emission

Abstract

The isomerization and optical properties of the cis and trans isomers of tetraphenylethene (TPE) derivatives with aggregation-induced emission (AIEgens) have been sparsely explored. We have now observed the tautomerization-induced isomerization of a hydroxy-substituted derivative, TPETH-OH, under acidic but not under basic conditions. Replacing the proton of the hydroxy group in TPETH-OH with an alkyl group leads to the formation of TPETH-MAL, for which the pure cis and trans isomers were obtained and characterized by HPLC analysis and NMR spectroscopy. Importantly, cis-TPETH-MAL emits yellow fluorescence in DMSO at -20 °C whereas trans-TPETH-MAL shows red fluorescence under the same conditions. Moreover, the geometry of cis- and trans-TPETH-MAL remains unchanged when they undergo thiol-ene reactions to form cis- and trans-TPETH-cRGD, respectively. Collectively, our findings improve our fundamental understanding of the cis/trans isomerization and photophysical properties of TPE derivatives, which will guide further AIEgen design for various applications.

Porous Hydrogen-Bonded Organic Frameworks

“…To expand application scope of planar rigid cores, tetrasubstituted ZnTDPP (zinc 5,10,15,20-tetrakistetra(4-cyanophenyl)porphyrin) and tetraphenylethylene (TPE) scaffolds were employed in order to explore porous materials with new functions [ 80 , 81 ]. It is well known that porphyrin and TPE derivatives have been extensively investigated in optoelectronic materials such as dye sensitized solar cells (DSSCs) [ 82 ] with high efficiency and aggregate induced emission (AIE) materials [ 83 ]. However, they were barely reported for the construction of HOF materials.…”

Identification of Potent Caspase‐8 Inhibitors from a Library of Fluorescent Natural Products Screened by an AIEgen‐Based Light‐Up Probe

“…During the design of the probe intended to target caspase‐8, an AIEgen based on the tetraphenylethylene–thiophene (TPETH) system was employed because it possessed a large Stokes shift of 200 nm and so could avoid interference from the innate fluorescence of the screened natural products . The DIETDC peptide sequence was used.…”

Recent Advances in the Z/E Isomers of Tetraphenylethene Derivatives: Stereoselective Synthesis, AIE Mechanism, Photophysical Properties, and Application as Chemical Probes

“…In 2016, Zhang et al elaborately designed severalT PE-based Z/E isomers, as shown in Scheme 4. [57] First, they synthesized TPETH-OH isomers, which wereo btained as am ixture and could not be separated by using column chromatography. However,t he isomersc ould be isolated by using reverse-phase HPLC with MeCN/water and 0.1% trifluoroacetic acid (TFA) as an eluent.…”

“…In 2016, Zhang et al. elaborately designed several TPE‐based Z / E isomers, as shown in Scheme . First, they synthesized TPETH‐OH isomers, which were obtained as a mixture and could not be separated by using column chromatography.…”