Aggregation‐induced multicolor luminescent nanoparticles with adaptive and fixed cores derived from brominated tetraphenylethene‐containing block copolymer

Abstract

Aggregation‐induced emission (AIE)‐active nanoparticles (NPs) exhibiting multicolor fluorescence and high‐quantum yields independent of the environment are important for the further development of next‐generation smart fluorescent materials. In this work, AIE‐active amphiphilic block copolymers were designed and synthesized by RAFT polymerization of a brominated tetraphenylethene (TPE)‐containing acrylate (A‐TPE‐Br). The block copolymer exhibited typical AIE effects in selective solvents, which can be explained by hydrophobic TPE aggregated in the core during micelle formation. Luminescent core–shell NPs with a crosslinked AIE core (fixed structure) were synthesized by the Suzuki coupling reaction of the bromine groups of the assembled block copolymer and boronic acid compounds. The NPs composed of TPE/thiophene crosslinked core showed green emission in both diluted state and solid state, implying the ability to fluoresce regardless of environmental changes and molecular dispersion. Multicolor luminescent NPs capable of changing color from blue to red were synthesized by changing the coupling compounds, such as anthracene for electron‐rich units and benzothiadiazole for electron‐deficient units. The effects of the nature of the donor and acceptor, as well as their combination (TPE/donor/acceptor sequence), on the color and fluorescent intensity of the core crosslinked NPs in the nonpolar and polar solvents, and solid state, were investigated.

Threonine-Based Stimuli-Responsive Nanoparticles with Aggregation-Induced Emission-Type Fixed Cores for Detection of Amines in Aqueous Solutions

“…The particle size and distribution of NP(Fl) determined by DLS in DMF and THF were similar to those in methanol ( Figure S7b ), implying no detectable interparticle aggregation. A similar tendency was observed in AIE-active NPs with fixed tetraphenylethene-based units in the cross-linked cores, which displayed characteristic fluorescence regardless of environmental changes, such as solvent polarities [ 56 , 57 ].…”

“…The UV–vis spectra and fluorescence spectra were recorded on a JASCO (Tokyo, Japan) V-630BIO UV–vis spectrophotometer and a JASCO FP-6100 spectrofluorophotometer, respectively. Fluorescence quantum yields of solutions were determined relative to 9,10-diphenylanthracene (sublimation grade) in cyclohexane [ 56 ]. Dynamic light scattering (DLS) was performed using a Zetasizer Nano (Sysmex/Marvern, Kobe, Japan) with a He-Ne laser (633 nm) at a detection angle of 173°.…”

“…The design and synthesis of core-cross-linked NPs derived from self-assembled block copolymers is one of the most extensively studied topics in the fields of polymer-based nanotechnology and polymeric micelles [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. We have previously developed core-cross-linked NPs with various optoelectronic and conjugated cores, such as electron-rich polythiophene and (di)thiophene [ 47 , 48 , 49 , 53 ], electron-transporting rylene bisimide [ 50 ], fluorescent anthracene [ 51 ], π-conjugated dithiophene [ 49 ], donor-acceptor [ 54 , 55 ], and tetraphenylethylene-based aggregation-induced emission (AIE) units [ 56 , 57 ]. Following micelle formation in selective solvents, an in situ Suzuki coupling reaction was conducted with diboronic acids, leading to the transformation of reactive block copolymers into stable core-cross-linked NPs with optoelectronic cores [ 47 , 48 , 49 , 53 , 54 , 55 , 56 , 57 ].…”

“…We have previously developed core-cross-linked NPs with various optoelectronic and conjugated cores, such as electron-rich polythiophene and (di)thiophene [ 47 , 48 , 49 , 53 ], electron-transporting rylene bisimide [ 50 ], fluorescent anthracene [ 51 ], π-conjugated dithiophene [ 49 ], donor-acceptor [ 54 , 55 ], and tetraphenylethylene-based aggregation-induced emission (AIE) units [ 56 , 57 ]. Following micelle formation in selective solvents, an in situ Suzuki coupling reaction was conducted with diboronic acids, leading to the transformation of reactive block copolymers into stable core-cross-linked NPs with optoelectronic cores [ 47 , 48 , 49 , 53 , 54 , 55 , 56 , 57 ]. In this study, an efficient synthetic method was adopted in which amphiphilic block copolymers, with the hydrophilic segment derived from AThrOH and the cross-linkable hydrophobic segment derived from 4-bromophenyl vinyl sulfide (BPVS), were synthesized by addition-fragmentation chain-transfer (RAFT) polymerization and one-pot core cross-linking of the assembled block copolymers by Suzuki coupling reactions.…”

Aggregation-induced emission-active micelles: synthesis, characterization, and applications

“…3c). 37 Because the hydrophobic TPE gathered in the center of the micelle during its formation, the block copolymer displayed the expected AIE effects in specific solvents. Subsequently, the Suzuki reaction between the boronic acid molecules and bromine groups in the constructed copolymer was used to further synthesize luminescent nanoparticles with an AIE core.…”