Highly Efficient Multiphoton-Absorbing Quadrupolar Oligomers for Frequency Upconversion
Highly Efficient Multiphoton-Absorbing Quadrupolar Oligomers for Frequency Upconversion
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DOI：
10.1002/chem.201002227
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发表时间：
2011-02-01
影响因子：
4.3
通讯作者：
Cheah, Kok Wai
中科院分区：
文献类型：
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作者：
Feng, Xin Jiang;Wu, Po Lam;Cheah, Kok Wai
以1，2，4-三氮唑（TAZ）为中心核，以D-pi-A-pi-D为结构单元，合成了两个四极二苯胺基封端的低聚芴PhN-OF（n）-NPh（n=2-5）和PhN-OF（n）-TAZ-OF（n）-NPh（n=1-4（D=给体，A=受体），通过钯催化的9，9-双-7-甲基-2，4-二氧杂环己烷的Suzuki交叉偶联合成。（二苯基氨基）-2-芴基硼酸和相应的（1，2，4-三唑基）芳基卤作为关键步骤。在红外飞秒激光泵浦下，这些低聚物显示出非常强的多光子激发蓝光。这些D-pi-D和D-pi-A-pi-D四极低聚芴与相应的D-pi-A对应物相比表现出上级三光子吸收性质，具有高达2.72 × 10（-77）cm（6）s（2）的最高三光子吸收截面（σ（3））。尽管PhN-OF（n）-NPh和PhN-OF（n）-TAZ-OF（n）-NPh两种四极低聚物具有可比的线性和多光子吸收性质，但只有前者表现出非常强烈和高效的多光子激发频率上转换深蓝激光，其产生了创纪录的0.097%的高激光效率和非常窄的激光光谱半峰全宽。我们的研究结果表明，四极型分子/低聚物是上级的多光子激发频率上转换激光的偶极对应物，也提供了重要的指导方针，设计高效的三光子吸收分子的光致发光和激光应用。
Two series of quadrupolar diphenylamino-endcapped oligofluorenes, PhN-OF(n)-NPh (n=2-5) and PhN-OF(n)-TAZ-OF(n)-NPh (n=1-4), which have an electron-withdrawing 1,2,4-triazole (TAZ) moiety as central core, with D-pi-A-pi-D structural motif (D=donor, A=acceptor), have been synthesized by palladium-catalyzed Suzuki cross-coupling of 9,9-dibutyl-7-(diphenylamino)-2-fluorenylboronic acid and the corresponding (1,2,4-triazole-based) aryl halide as key step. On pumping with infrared femtosecond lasers, these oligomers showed very strong multiphoton-excited blue photo-luminescence. These D-pi-D and D-pi-A-pi-D quadrupolar oligofluorenes exhibit superior three-photon absorption properties compared to the respective D-pi-A counterparts with a highest three-photon absorption cross-section (sigma(3)) of up to 2.72 x 10(-77) cm(6)s(2). Despite the comparable linear and multiphoton absorption properties of the two types of quadrupolar oligomers PhN-OF(n)-NPh and PhN-OF(n)-TAZ-OF(n)-NPh, only the former exhibit remarkably intense and highly efficient multiphoton-excited frequency-upconverted deep blue lasing, which gives rise to record high lasing efficiency of 0.097% and very narrow of full width at half-maximum of the lasing spectra. Our findings suggest that quadrupolar-type molecules/oligomers are superior for multiphoton excited frequency upconverted lasing to their dipolar counterparts and also provide important guidelines to design highly efficient three-photon absorption molecules for photoluminescence and lasing applications.