Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole

Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

Aggregation-Induced Emission: Together We Shine, United We Soar!

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure–property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).

Aggregation-induced emission

The Huisgen 1,3-dipolar cycloaddition reaction of organic azides and alkynes has gained considerable attention in recent years due to the introduction in 2001 of Cu(1) catalysis by Tornoe and Meldal, leading to a major improvement in both rate and regioselectivity of the reaction, as realized independently by the Meldal and the Sharpless laboratories. The great success of the Cu(1) catalyzed reaction is rooted in the fact that it is a virtually quantitative, very robust, insensitive, general, and orthogonal ligation reaction, suitable for even biomolecular ligation and in vivo tagging or as a polymerization reaction for synthesis of long linear polymers. The triazole formed is essentially chemically inert to reactive conditions, e.g. oxidation, reduction, and hydrolysis, and has an intermediate polarity with a dipolar moment of ∼5 D. The basis for the unique properties and rate enhancement for triazole formation under Cu(1) catalysis should be found in the high ∆G of the reaction in combination with the low character of polarity of the dipole of the noncatalyzed thermal reaction, which leads to a considerable activation barrier. In order to understand the reaction in detail, it therefore seems important to spend a moment to consider the structural and mechanistic aspects of the catalysis. The reaction is quite insensitive to reaction conditions as long as Cu(1) is present and may be performed in an aqueous or organic environment both in solution and on solid support.

Cu-catalyzed azide-alkyne cycloaddition.

Aggregation-induced emission: phenomenon, mechanism and applications.

Development of advanced polymeric materials with both liquid crystallinity and light emissivity is of scientific interest and technological importance. In this study, we studied light emission from tetrahydrofuran solutions of a liquid crystalline polyacetylene, poly(11-{[(4'-heptoxy-4- biphenylyl)carbonyl]oxy}-1-undecyne), in the electrical field. The field exerts little effect on the photoluminescence of the polymer solution with a low concentration (0.10 mM). The photoluminescence of a concentrated solution (11.3 mM) is, however, noticeably quenched under an electrical field with a field strength of > 300 kV/m. When the field strength is increased to >= 367 kV/m, the bimodal emission spectrum of the solution changes to a monomodal one. Thus, both the emission intensity and spectral profile of the luminescence of the concentrated solution can be tuned by the electrical field, which is probably caused by the aggregate dissociation and mesogen realignment induced by the external stimulus.

Liquid crystalline polyacetylenes with tunable luminescent properties

Booming AIE universe has set off an upsurge in recent years, driving much innovation in academic, industrial and medical world. Superb reliability and biocompatibility equip AIE dots with tremendous potential for fluorescence bioimaging and even clinical translation. The utilization on non-human primates imaging are vital for AIE dots assisted clinical theranostics, which still remains unexplored yet. Additionally, fluorescence bioimaging in second near-infrared window (NIR-II, 900-1700 nm) is widely recognized as an effective technology for deep-penetration mammals optical imaging. Here, we designed a novel AIEgen with a large molar extinction coefficient of nearly 5×10e4 /(mM cm) at 770 nm and the PEGylated AIE dots possessed an extremely high NIR-II photoluminescence quantum yield (PLQY) as 13.6%, exhibiting bright fluorescence beyond 1100 nm and even 1500 nm (near-infrared IIb, NIR-IIb). Assisted by the AIE dots, large-depth cerebral vasculature (beyond 600 μm) as well as real-time blood flowing were monitored through the skull and high-spatial-frequency non-invasive NIR-IIb (beyond 1500 nm) imaging gave a precise presentation of gastrointestinal tract in marmosets. Importantly, after intravenous or oral administration, the definite excretion of AIE dots from the body was demonstrated. It was the first attempt for AIE dots assisted NIR-II fluorescence imaging in non-human primates and we wished this work could promote the development of AIE dots for clinical application.

https://biorxiv.org/content/10.1101/2020.05.26.113316v1.full.pdf

An exploratory rehearsal on AIE dots assisted NIR-II fluorescence non-human primates imaging

Hyperbranched Polyphenylenes: Synthesis, Light Emission, and Optical Limiting Properties

Development of new methods for the construction of regioselective hyperbranched macromolecules: Synthesis of functional hyperbranched poly(aroylarylene)s

Poly(phenylacetylene)s bearing monosaccharide pendant groups are synthesized in high yields by [Rh(nbd)Cl]2 catalyst. The polymers have high molecular weights and give satisfactory spectroscopic data corresponding to their molecular structures. They are thermally quite stable (≥ 300°C) and show strong circular dichroism signals in the visible spectral region owing to the helicity of the polyene backbone. The monosaccharide-containing polyacetylenes are cytophilic and can stimulate the growth of living cells.

Jacky Wing Yip Lam

Papers

Liquid crystalline polyacetylenes with tunable luminescent properties

An exploratory rehearsal on AIE dots assisted NIR-II fluorescence non-human primates imaging

Hyperbranched Polyphenylenes: Synthesis, Light Emission, and Optical Limiting Properties

Development of new methods for the construction of regioselective hyperbranched macromolecules: Synthesis of functional hyperbranched poly(aroylarylene)s

Synthesis, helicity, and biological properties of monosaccharide-containing poly(phenylacetylene)s