Synthesis, light emission, nanoaggregation, and restricted intramolecular rotation of 1,1-substituted 2,3,4,5-tetraphenylsiloles
Synthesis, light emission, nanoaggregation, and restricted intramolecular rotation of 1,1-substituted 2,3,4,5-tetraphenylsiloles
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DOI：
10.1021/cm021715z
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发表时间：
2003-04-08
影响因子：
8.6
通讯作者：
Tang, BZ
中科院分区：
文献类型：
--
作者：
Chen, JW;Law, CCW;Tang, BZ
制备了一系列10个具有不同1，1-取代基的2，3，4，5-四苯基硅杂环戊二烯[XYSi（CPh）（4）]，其中3个，即，对1，1，2，3，4，5-六苯基硅杂环戊二烯[X = Y = Ph（3）]、1-乙炔基-1，2，3，4，5-五苯基硅杂环戊二烯[X = Ph，Y = CdropCH（15）]和1，1-双（苯乙炔基）-2，3，4，5-四苯基硅杂环戊二烯[X = Y = CdropCPh（18）]进行了晶体学表征。1，1-取代基的诱导效应影响了噻咯的基态和激发态：随着其电负性的增加，噻咯的吸收和发射光谱发生红移。建立了一种简单可靠的薄层色谱法测定硅杂环戊二烯类化合物的固体发光光谱。当在室温下以分子形式溶解在普通溶剂中时，所有的噻咯几乎都不发射（“关闭”）。当添加不良溶剂时，噻咯分子聚集成纳米聚集体，这将发射“打开”并将光致发光量子产率提高高达2个数量级（聚集诱导发射）。提高溶液的粘度和降低溶液的温度也能显著提高噻咯的发光强度。溶液的增稠和冷却实验表明，聚集诱导的发光是由周围的芳香环的限制性的分子内旋转轴上的单键连接到中心的silole核心。
A series of ten 2,3,4,5-tetraphenylsiloles with different 1,1-substituents [XYSi(CPh)(4)] were prepared, and three of these, i.e., 1,1,2,3,4,5-hexaphenylsilole [X = Y = Ph (3)], 1-ethynyl-1,2,3,4,5-pentaphenylsilole [X = Ph, Y = CdropCH (15)], and 1,1-bis(phenylethynyl)-2,3,4,5-tetraphenylsilole [X = Y = CdropCPh (18)], were characterized crystallographically. The ground-and excited-states of the siloles were influenced by the inductive effect of the 1,1-substituents: with an increase in their electronegativity, the absorption and emission spectra of the siloles bathochromically shifted. A simple and reliable TLC-based method was developed for measurement of the solid-state luminescence spectra of the siloles. When molecularly dissolved in common solvents at room temperature, all the siloles were practically nonemissive ("off"). When poor solvents were added, the silole molecules clustered into nanoaggregates, which turned the emission "on" and boosted the photoluminescence quantum yields by up to 2 orders of magnitude (aggregation-induced emission). The silole emission could also be greatly enhanced by increasing the viscosity and decreasing the temperature of the silole solutions. The solution thickening and cooling experiments suggest that the aggregation-induced emission is caused by the restricted intramolecular rotations of the peripheral aromatic rings upon the axes of the single bonds linked to the central silole cores.