Click polymerizations with remarkable advantages have been nurtured into powerful polymerization techniques with widespread applications. In this overview, several types of click polymerizations and their applications are briefly summarized. Of these, azide-alkyne click polymerizations (AACPs) are the most widely used due to the easy availability of the monomers and the stability of the products. AACPs catalyzed by Cu(i) and Ru(ii) can offer 1,4- and 1,5-regioregular PTAs, respectively. Meanwhile, 1,4-regioregular PTAs can also be obtained via metal-free click polymerizations of activated alkynes and azides or activated azides and alkynes. 1,5-regioregular PTAs can be produced by organic base-mediated AACP. Thiol-ene click polymerizations are versatile tools for the preparation of polythioethers with linear and hyperbranched structures. Similarly, thiol-yne click polymerizations, as the updated version of the former, can provide polythioethers and poly (vinyl sulfide)s (PVSs) with diverse structures. Novel reversible polymers can be yielded via Diels-Alder click polymerizations. Some new click polymerizations have also been researched for the synthesis of functional polymers with various structures. With these efficient polymerization techniques in hand, polymer scientists have prepared a large number of polymers with unique properties, such as luminescence, photonic patterning, adjustable light refractivity, optical nonlinearity, biodegradability, catalyst activity, self-assembly and self-healing.

Huang Die    Anjun Qin    唐本忠    

RSC Polymer Chemistry Series

2018

This chapter gives a summary of the recent research efforts devoted to the development of transition metal-catalyzed azide-alkyne click polymerizations (AACPs) and their applications in the preparation of linear and hyperbranched polytriazoles (PTAs) with advanced functions. Cu(i)- and Ru(ii)-catalyzed AACPs can yield 1,4- and 1,5-regioregular PTAs, respectively. Various Cu(i) complexes have been applied as catalysts for AACPs. The produced PTAs showed unique properties, such as luminescence, fluorescence imaging, biodegradability, optical nonlinearity, stimulus-responsiveness, thermal stability, self-assembly and catalytic activity.

Huang Die    Anjun Qin    唐本忠    

RSC Polymer Chemistry Series

2018

Multicomponent polymerizations (MCPs) have received widespread attention and are becoming a powerful tool for the synthesis of polymers. The Cu()-catalyzed MCPs are a vibrant branch of multicomponent polymerizations, which inherit the various advantages of multicomponent reactions (MCRs) and click reactions. This chapter will focus on the development of Cu()-catalyzed MCRs in polymer synthesis. Click reaction-mediated multicomponent polymerization has been applied for the synthesis of a library of linear, hyperbranched, core-shell-type, graft and dendronized polymers with high molecular weights and high yields, which show great potential for the construction of functional polymer materials.

Tian Wen    胡蓉蓉    唐本忠    

RSC Polymer Chemistry Series

2018

Cu(i)-catalyzed azide-alkyne click polymerization has been widely applied in diverse areas. However, the removal of metal residues from the products is not a trivial task. To completely surmount this difficulty, the metal-free click polymerization (MFCP) of azides and alkynes is highly demanded. In this chapter, the recent developments of alkyne-azide MFCP are summarized, and the properties and applications of the resultant polytriazoles are introduced. Meanwhile, the opportunities and challenges in this area are also briefly discussed.

Li Baixue    Anjun Qin    唐本忠    

RSC Polymer Chemistry Series

2018

Luminescent materials with high thiophene contents generally suffer from severe emission quenching in the aggregated state, owing to various active nonradiative decay channels. Herein, we report that a series of novel propeller-like luminogens consisting of a thieno[3,2-b]thiophene S,S-dioxide core and different phenyl rotors can behave oppositely. They show faint emission in solutions, but can fluoresce strongly in solid films, displaying prominent aggregation-induced emission (AIE) nature. Crystallographic, computational, and spectroscopic results reveal the synergistic effect of a propeller-like conformation and the oxidation of thieno[3,2-b]thiophene to thieno[3,2-b]thiophene S,S-dioxide greatly enhances emission efficiency of the luminogen in solid film. Calculation and electrochemical experiments reveal that they have much lower LUMO energy levels than the unoxidized counterparts. This work not only presents a feasible approach to create robust luminescent materials from thiophene by oxidation but also provides a new AIE platform with advantages of structural variety, high solid-state emission efficiency, and strong electron affinity for optoelectronic and biological applications.

Bin Chen    Zhang Han    Luo Wenwen    Han Nie    胡蓉蓉    Anjun Qin    Zujin Zhao    唐本忠    

Journal of Materials Chemistry C

2017

The development of new polymerization reactions conducted under monomer non-stoichiometric conditions has great academic and industrial significance. Herein we report such a new route for synthesizing functional polynaphthalenes (PNs). The polycoupling reactions of benzoic acid and its derivatives (1) with 4,4′-(1,6-hexylenedioxy)bis(diphenylacetylene) (2) proceed smoothly in o-xylene in the presence of [Cp*IrCl] and AgCO at 140 °C, generating multisubstituted PNs with high molecular weights (M up to 228 700) in high yields (up to 98%). The effect of monomer stoichiometry on the polymerization was systematically investigated and the best result was obtained at a molar feed ratio of 1 : 2 of 2 : 1. The associated mechanism for the monomer non-stoichiometry enhancement effect was proposed. All the obtained PNs show good thermal stability and excellent optical transparency. They possess good film-forming ability and their thin films exhibit high refractive indices (n = 1.7653-1.6354). Polymers constructed from non-emissive monomers show light emission in solutions due to the generation of fluorophores in situ during the polymerization. The polymer carrying a tetraphenylethene motif is weakly emissive in solution but emits intensely when aggregated, demonstrating a phenomenon of aggregation-induced emission. The efficient solid-state emission and good photosensitivity enable it to be utilized as a material for fabricating two-dimensional fluorescent photopatterns by irradiating its thin films under UV light through copper masks.

Ting Han    Zhao Zheng    Haiqin Deng    Ryan tsz kin Kwok    Lam Jacky W. Y.    唐本忠    

Polymer Chemistry

2017

Construction of a donor-acceptor (D-A) structure and extension of π-conjugation are the commonly used strategies to shift the emission of luminophores to the red region. However, molecules with high conjugation and a strong D-A effect tend to show weak emission due to the severe π-π interactions and twisted intramolecular charge transfer (TICT) effects. The turn-on characteristic of AIE luminogens (AIEgens) will also be lost due to the conjugation-enhanced emission in the solution state. Herein, a polyyne-bridged AIE luminogen (2TPE-4E) with long wavelength absorption and red emission has been afforded. Despite its large π-conjugation, 2TPE-4E suffers from no emission quenching resulted from strong π-π interactions and twisted intramolecular charge transfer effects. The strong red emission and the high photostability of 2TPE-4E inspired us to use it for targeted-imaging of cancer cells and monitoring the receptor mediated endocytosis process.

Zhao Zheng    Su Huifang    Zhang Pengfei    Cai Yuanjing    Ryan tsz kin Kwok    Chen Yuncong    He Zikai    Xinggui Gu    He Xuewen    Sung Herman H. Y.    Willimas Ian D.    Lam Jacky W. Y.    Zhang Zhenfeng    唐本忠    

Journal of Materials Chemistry B

2017

Furan-cored AIEgen namely tetraphenylethylene-furan (TPE-F) is developed by diyne cyclization and its fluorescent and chemical properties are investigated and compared with its thiophene analogue. Results show that furan is superior to thiophene in terms of fluorescence, chromism, and charge transport. The mechanism of chromism of TPE-F is investigated and its efficient solid-state photoluminescence and good charge-transporting property enable it to serve as light-emitting material for the construction of electroluminescence devices with excellent performance. This work not only demonstrates an efficient strategy for constructing furan-cored AIEgens but also indicates that they are promising as advanced optoelectronic materials.

Zhao Zheng    Han Nie    Ge Congwu    Cai Yuanjing    Xiong Yu    Qi Ji    Wu Wenting    Ryan tsz kin Kwok    Gao Xike    Anjun Qin    Lam Jacky W. Y.    唐本忠    

Advanced Science

2017

Cancer is the leading cause of death worldwide. With the advantages of low cost, high sensitivity and ease of accessibility, fluorescence imaging has been widely used for cancer detection in the scientific field. Aggregation-induced emission luminogens (AIEgens) are a class of synthesized fluorescent probes with high brightness and photostability in the aggregate state. Herein, a new positively-charged AIEgen, abbreviated as TPE-IQ-2O, is designed and characterized. TPE-IQ-2O not only can distinguish cancer cells from normal cells with high contrast with the aid of the difference in mitochondrial membrane potential as well as the quantity of mitochondria, but it also works as a promising photosensitizer to kill cancer cells through generation of reactive oxygen species upon white light irradiation, thus making it a promising AIE theranostic system.

Gui Chen    Engui Zhao    Ryan tsz kin Kwok    Leung Anakin C.S.    Lam Jacky W. Y.    Jiang Meijuan    Haiqin Deng    Cai Yuanjing    Zhang Weijie    Su Huifang    唐本忠    

Chemical Science

2017

A novel dark through-bond energy transfer (DTBET) strategy is proposed and applied as the design strategy to develop ratiometric Hg sensors with high performance. Tetraphenylethene (TPE) derivatives with aggregation-induced emission (AIE) characteristics are selected as dark donors to eliminate emission leakage from the donors. The TBET mechanism has been adopted since it experiences less influence from spectral overlapping than Förster resonance energy transfer (FRET), making it more flexible for developing cassettes with large pseudo-Stokes shifts. In this work, energy transfer from the TPE derivatives (dark donor) to a rhodamine moiety (acceptor) was illustrated through photophysical spectroscopic studies and the energy transfer efficiency (ETE) was found to be up to 99%. In the solution state, no emission from the donors was observed and large pseudo-Stokes shifts were achieved (>280 nm), which are beneficial for biological imaging. Theoretical calculations were performed to gain a deeper mechanistic insight into the DTBET process and the structure-property relationship of the DTBET cassettes. Ratiometric Hg sensors were rationally constructed based on the DTBET mechanism by taking advantage of the intense emission of TPE aggregates. The Hg sensors exhibited well resolved emission peaks. >6000-fold ratiometric fluorescent enhancement is also achieved and the detection limit was found to be as low as 0.3 ppb. This newly proposed DTBET mechanism could be used to develop novel ratiometric sensors for various analytes and AIEgens with DTBET characteristics will have great potential in various areas including light harvesting materials, environmental science, chemical sensing, biological imaging and diagnostics.

Chen Yuncong    Zhang Weijie    Cai Yuanjing    Ryan tsz kin Kwok    Hu Yubing    Lam Jacky W. Y.    Xinggui Gu    He Zikai    Zhao Zheng    Zheng Xiaoyan    Bin Chen    Gui Chen    唐本忠    

Chemical Science

2017