E/Z isomerization effects on aggregation-enhanced emission of tetraphenylethene derivatives assisted by host–guest recognition

Abstract

Pure stereoisomers of tetraphenylethene derivatives functionalized with dibenzylamine groups, E and Z conformers, were successfully synthesized. Their aggregation-enhanced emissions, which occurred through host-guest recognition with a dibenzo-24-crown-8 based tetraphenylethene under an acid condition, showed recognizable isomerization effects. Scheme 1 Synthetic routes of E-2DBA-TPE, Z-2DBA-TPE and 4DB24C8-TPE. Inset: photographs of solid powders of E-2DBA-TPE and Z-2DBA-TPE under UV irradiation at 365 nm. Electronic supplementary information (ESI) available: Synthesis and characterization of 4DB24C8-TPE, E-2DBA-TPE and Z-2DBA-TPE, DLS plots, SEM and TEM images of E/Z supramolecular polymers. See

Isomeric Pair of E/Z Tetraphenylethene-Cored Luminogens Showing Distinguishing Mechanoresponsive Luminescence Turn-On and Two-Color Behavior

“…Syntheses and EZI Conformation Changes. As shown in Scheme S1, a mixture of E/Z stereoisomers of TPE2PCHO, 26 prepared by the Suzuki cross-coupling reaction without isomeric separation, was subjected to Knoevenagel condensation with malonodinitrile in the presence of a catalytic amount of piperidine (5.0% equiv). It is noted that the dicyanovinyl functionalization can enable the macroscopic separation of pure E and Z stereoisomers of TPE2PD as yellow and orange powders, respectively, because they have distinguishing R f values (0.32 vs 0.41 in thin-layer chromatography using a CH 2 Cl 2 /petroleum ether mixture (v/v = 4:3) as the developing agent).…”

“…Cis–trans isomerization is an interesting and important phenomenon in chemistry. − Efficient control of the cis–trans process promises innovative switchable optoelectronic device applications. , For example, azobenzene derivatives are one of the main focuses as reversible responsive materials, where the cis–trans isomerization is generally triggered by light and/or heat stimuli . In fact, TPE derivatives are commonly synthesized via a one-step Ti-catalyzed McMurry coupling reaction, and the final products are always collected as a stereoisomeric mixture containing both E and Z conformers.…”

“…In fact, TPE derivatives are commonly synthesized via a one-step Ti-catalyzed McMurry coupling reaction, and the final products are always collected as a stereoisomeric mixture containing both E and Z conformers. The separation of the pure TPE E / Z isomers is still highly challenging, which is the main obstacle to further elucidating their fundamental properties. ,− …”

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

“…In 2017, Li et al synthesized pure (Z)-/(E)-TPE isomers by incorporating polar benzaldehyde and dibenzylamine groups into the TPE framework ( Figure 14). [74] They successfully separated (Z)-2CHO-TPE and (E)-2CHO-TPE by using column chromatography,a nd their further in situ treatment with benzylamine produced the corresponding imine compounds, which were subsequently reduced with sodium borohydridet oa fford (Z)-2DBA-TPE and (E)-2DBA-TPE, respectively.T he geometries of the Z and E isomersw ere confirmed by using NOESY and COSY NMR spectroscopy. ( E)-2DBA-TPE showed am uch larger hypochromics hift and better supramolecularp olymerization than (Z)-2DBA-TPE.…”

“…In 2017, Li et al. synthesized pure ( Z )‐/( E )‐TPE isomers by incorporating polar benzaldehyde and dibenzylamine groups into the TPE framework (Figure ) . They successfully separated ( Z )‐2CHO‐TPE and ( E )‐2CHO‐TPE by using column chromatography, and their further in situ treatment with benzylamine produced the corresponding imine compounds, which were subsequently reduced with sodium borohydride to afford ( Z )‐2DBA‐TPE and ( E )‐2DBA‐TPE, respectively.…”