Tetraphenylpyrazine-based AIEgens: facile preparation and tunable light emission

Abstract

Structurally new AIEgens with tunable emission based on tetraphenylpyrazine were rationally designed and readily prepared.

Multifunctional AIEgens: Ready Synthesis, Tunable Emission, Mechanochromism, Mitochondrial, and Bacterial Imaging

“…The isomers are very hard to separate and thus they are often used in a mixture, leading to a complicated situation of mechanistic understanding; [13] (2) many double-bond containing AIEgens, such as Schiff bases and dicynao-substituted compounds, are vulnerable to nucleophiles, such as CN − , HS − , and OH − , [14] making them chemically unstable; and (3) the double bonds easily undergo photoisomerization and photooxidization upon excitation, leading to low photostability. [12] On the other hand, Type II AIEgens are of well-defined structures with more clear AIE mechanism, better chemical and photostabilities. Their syntheses, however, are not readily accessible, and they require multiple steps and strict synthetic conditions.…”

“…Their syntheses, however, are not readily accessible, and they require multiple steps and strict synthetic conditions. [12] Thus, it would be satisfactory to integrate the merits of Types I and II and to develop novel AIEgens.…”

“…[9] While in Type II, they are only consisted of aromatic rings, such as hexaphenylsilole (HPS), [3a,10] borondiiminates, [11] and tetraphenylpyrazine (TPP). [12] The Type I AIEgens are relatively easy to synthesize and functionalize, so that a rich variety of AIEgens have been developed and used for practical applications. However, they suffer from defects of the double bonds: (1) E/Z isomers with different properties in photophysics and sensing are formed during syntheses.…”

Synthesis of Imidazole‐Based AIEgens with Wide Color Tunability and Exploration of their Biological Applications

“…[ 10 ] Although they possess good thermal-, photo-, and chemostabilities, their emission is only tunable from 390 to 460 nm. Similar to the structure of pyrazine, imidazole is a typical fi ve-membered N-heterocycle compound, whose derivatives are widely used as dyes, [ 11 ] catalysts, [ 12 ] drugs,…”

“…For traditional dyes, if too many molecules accumulate in a specifi c site, the concentration quenching effect will come into play which leads to fl uorescence quenching. [ 5 ] However, AIEgens will enjoy such an aggregation process to yield enhanced fl uorescence with high photobleaching resistance, which is highly desirable for biological applications.To date, numerous AIEgens have been developed based on different core structures such as tetraphenylethene (TPE), [ 6 ] hexaphenylsilole (HPS), [ 7 ] distyrylanthracene (DSA), [ 8 ] boron diiminates, [ 9 ] and tetraphenylpyrazine (TPP) [ 10 ] ( Scheme 1 ). However, most of these core structures emit in short wavelength region, normally blue or green.…”