Luminogenic materials constructed from tetraphenylethene building blocks: Synthesis, aggregation-induced emission, two-photon absorption, light refraction, and explosive detection
作者:Rongrong Hu、Jose Luis Maldonado、Mario Rodriguez、Chunmei Deng、Cathy K. W. Jim、Jacky W. Y. Lam、Matthew M. F. Yuen、Gabriel Ramos-Ortiz、Ben Zhong Tang
DOI:10.1039/c1jm13556b
日期:——
Luminogenic molecules [(TPE)3 (1), TPE-C = C-TPE-C = C-TPE (2), and TPE-C≡C-TPE-C≡C-TPE (3)] and their polymers P1–P3 are constructed from tetraphenylethene (TPE) building blocks in high yields by Suzuki, Witting, and Sonogashira coupling reactions. All the compounds are soluble and enjoy high thermal stability, losing little of their weights when they are heated to 290–528 °C under nitrogen or 288–436 °C in air. Analyses by UV spectroscopy and cyclic voltammetry as well as theoretical calculations show that the conjugation of the luminophores is in the order of 2 > 3 > 1, P2 > P3 > P1, and P1–P3 > 1–3. All the molecules and polymers are weakly emissive in solutions. They, however, become strong emitters in the aggregate state with fluorescence quantum yields up to 90%. Both 1–3 and P1–P3 exhibit the feature of aggregation-enhanced two-photon excited fluorescence. Large two-photon absorption cross sections (up to ∼900 GM) are observed in the nanoaggregates of the polymers. Thin solid films of the polymers show high refractive indices (RI = 1.7649 − 1.6873) in a wide wavelength region of 400–1700 nm, high modified Abbé numbers (vD′ up to 3436), and low optical dispersions (D′ down to 2.9 × 10−4). The light emissions of the polymers can be quenched exponentially by picric acid with large quenching constants, suggesting that they can be utilized as efficient chemosensors for explosive detection.
发光分子[(TPE)3 (1),TPE-C=C-TPE-C=C-TPE (2)和TPE-C≡C-TPE-C≡C-TPE (3)]及其聚合物P1–P3由四苯乙烯(TPE)单元以高产率通过铃木、维廷和园田耦合反应构建而成。所有化合物均可溶,并具有高热稳定性,在氮气下加热至290–528 °C或在空气中加热至288–436 °C时,仅损失少量重量。通过紫外光谱、循环伏安法以及理论计算的分析表明,发光单元的共轭程度顺序为2 > 3 > 1,P2 > P3 > P1,以及P1–P3 > 1–3。所有分子和聚合物在溶液中发射强度较弱。然而,它们在聚集态中变为强发射体,荧光量子产率可高达90%。1–3和P1–P3均表现出聚集增强的双光子激发荧光特征。在聚合物的纳米聚集体中观察到较大的双光子吸收截面(达约900 GM)。聚合物的薄固体薄膜在400–1700 nm的宽波长区域内显示出高折射率(RI = 1.7649 − 1.6873)、高修正阿贝数(vD′高达3436)和低光学色散(D′低至2.9 × 10−4)。聚合物的光发射可被硝基苯酸以指数方式淬灭,且淬灭常数较大,表明它们可以作为高效的化学传感器用于爆炸物检测。