Tetraphenylethene-Containing Alkynone Derivatives: Design and Synthesis, Aggregation-Induced Emission Characteristics, and the Selective Fluorescence Detection of Pd²⁺

聚集誘導發光（AIE）材料吸引了許多光電器件和生物熒光技術領域的科學家的關注.對聚集誘導發光化合物構效關係的深入理解對於設計新材料至關重要.在本工作中，基於經典的AIE基元四苯基乙烯，設計並合成了一系列具有AIE性質，含不同電子給體/受體取代基的炔酮衍生物.對這一系列化合物的光物理性質進行了系統研究並分別探討了取代基團對發光波長、發光效率和AIE性質的影響.它們的聚集態最大發射波長位於511～565 nm，在四氫呋喃/水混合溶液中的熒光量子產率可達31%.在末端苯環上的電子給體/受體取代基團會降低聚集態的發光效率，而引入硝基取代基則會在發射波長紅移的同時，顯著猝滅熒光.最為重要的是，這些化合物結構中的炔酮基元可以在一系列金屬離子中選擇性地與Pd<sup>2+</sup>配位，猝滅納米聚集體的發光，並有望作為一個有效的Pd<sup>2+</sup>熒光傳感. Organic luminescent materials with aggregation-induced emission (AIE) characteristics have attracted much attention among the scientists in the fields of optoelectronic devices and fluorescence biotechnology. AIE materials overcomes the aggregation-caused quenching problem of traditional organic fluorescent compounds, which possess high fluorescence quantum efficiency in the aggregated states. Thanks to the great research effort of worldwide scientists, a large variety of AIE materials have been developed and the underlying mechanism has been rapidly explored. The deep understanding of the structure-property relationship of AIE compounds is still in an urgent demand for the design of new materials. In this work, based on the classical propeller-shaped AIEgen, tetraphenylethene (TPE), we designed and synthesized a series of electron donor/acceptor-containing alkynone derivatives with AIE feature such as cyano, nitro, butyl and butoxyl groups-substituted alkynone derivatives. Their chemical structures have been fully characterized by 1H NMR, 13C NMR, IR, and HRMS spectra, providing satisfactory analysis results. Their photophysical properties are systematically studied and the effect of substitution groups on the emission maximum, emission efficiency, as well as AIE property are discussed, respectively. Their emission maxima are located at 511~565 nm with the fluorescence quantum yields of up to 31% in the aggregated states in THF/water mixtures with high water content. The fluorescence intensity of the unsubstituted TPE-containing alkynone derivative in THF/H2O with φw=90% water content is 157 times higher than that in THF solution. It is suggested that both electron-donating and electron-withdrawing substitution groups on the terminal phenyl ring decrease the emission efficiency of the aggregated state and the introduction of nitro group dramatically quenches the emission while redshifts the emission maximum. Most importantly, the alkynone groups in these compounds can selectively coordinate with Pd2+ among a large variety of metal ions, which quench the emission of the nanoaggregates and possess high sensitivity towards Pd2+, demon-strating the potential application as an efficient Pd2+ fluorescent sensor. © 2016 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.