Configuration-Controllable E/Z Isomers Based on Tetraphenylethene: Synthesis, Characterization, and Applications

Abstract

Configuration-controllable E/Z isomers based on tetraphenylethene were prepared with a facile and effective method. First, compounds 1 and 2, configuration-controllable precursors of E/Z isomers, were synthesized. Then, pure E/Z isomers were obtained via Suzuki reaction, avoiding the difficulties of separation. The conformational changes of E/Z isomers can occur through photoactivation. Importantly, red-shifts of 66 nm from 6 (E-) to 3 (Z-) and 58 nm from 7 (E-) to 4 (Z-) were observed remarkably on the photoluminescence (PL) emission spectra. The Z isomer showed a longer fluorescence lifetime compared with the E isomer. The Z isomers 3 and 4 exhibited piezofluorochromism under grinding, whereas the E isomers 6 and 7 showed no such behaviors. The E isomer has better thermal stability than the Z isomer. Lastly, graphene-like molecules were synthesized with the FeCl3/CH3NO2 system. The E and Z isomers after oxidation showed negligible differences in the PL emission spectra because the effective conjugated lengths of oxidized E and Z isomers were both extended. Furthermore, the fabricated field-effect transistors showed nice performance with mobilities of 0.92 and 1.14 cm–2 V–1 s–1 at low operating voltages, respectively.

Designing highly fluorescent, arylated poly(phenylene vinylene)s of intrinsic microporosity

“…The higher bathochromic shift found for Mono-Np can be attributed to the increase in the conjugation segment promoted by the naphthyl moieties when compared with the phenyl units in TPE. 37 Clearly contrasting with the behavior found for TPE in good solvents, where fluorescence emission is almost negligible (with f F values of 0.002 or 0.0024 and of 0.003 in Table 3), 37,45,46 the phenyl-terminated monomeric model compounds, Mono-t-Bu and Mono-Np, display fluorescence both in solution and in the solid state ( Fig. 3 and Table 3).…”

Stereodefined tetraarylethylenes: Synthesis and applications

“…As displayed in Figure 4A(ii), ( E )‐1,2‐dibromo‐1,2‐diarylethene generated from trans ‐dibromination of diarylethyne could be converted into E ‐[2+2]‐TAEs 11 via the mild SMCC reaction. [ 80 ] Indeed, this synthetic protocol offered a new strategy for synthesizing E ‐[2+2]‐TAEs isomers which are challenging to prepare before, thereby obviating difficulties of separating isomers. It is believed that such transformation would become popular in the synthesis of E ‐[2+2]‐TAEs with the development of mild reaction conditions upon the trans‐dibromination of diarylethyne.…”

“…[ 78 ] Synthetic routes to E ‐TAEs (ii). [ 80 ] (B) Synthesis of tetraborylethylene (i). Synthetic routes to [4+0]‐, [3+1]‐, [2+2]‐, [2+1+1]‐TAEs from vinylboronates (ii).…”

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

“…Accordingly,t he TPE isomers showedd ifferent photophysical properties in terms of, for example,t heir mechanochromism (MC), mechanoluminescence (ML), solvatochromism (SC), and meltingp oints. [47][48][49][50] In 2012, during their syntheses of polycyclic aromatic TPE derivatives, Hu et al obtained am ixture of (Z)-/(E)-BETPEb y using the McMurry couplingr eaction ( Figure 5a). [51] However, they could not separate the Z and E isomersb yu sing column chromatography, because of their similar polarities, which were derived from the weak polarity of the ethynyl group.…”

“…Most of the pure Z / E isomers that have been reported have exhibited large polarity differences. Accordingly, the TPE isomers showed different photophysical properties in terms of, for example, their mechanochromism (MC), mechanoluminescence (ML), solvatochromism (SC), and melting points …”