Ferrer-Ugalde A, Cabrera-González J, Juárez-Pérez E J, Teixidor F, Pérez-Inestrosa E, Montenegro J M, Sillanpää R, Haukka M, Núñez R
Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus U.A.B., 08193, Bellaterra, Barcelona, Spain.
Universidad de Málaga, IBIMA, Department of Organic Chemistry, 29071-Malaga, Spain and Andalusian Centre for Nanomedicine and Biotechnology-BIONAND, Parque Tecnológico de Andalucía, 29590-Málaga, Spain.
Dalton Trans. 2017 Feb 14;46(7):2091-2104. doi: 10.1039/c6dt04003a.
Two novel styrene-containing meta-carborane derivatives substituted at the second carbon cluster atom (C) with either a methyl (Me) or a phenyl (Ph) group are introduced herein along with a new set of stilbene-containing ortho- (o-) and meta- (m-) carborane dyads. The latter set of compounds have been prepared from styrene-containing carborane derivatives via a Heck coupling reaction. High regioselectivity has been achieved for these compounds by using a combination of palladium complexes [Pd(dba)]/[Pd(t-BuP)] as a catalytic system, yielding exclusively E isomers. All compounds have been fully characterised and the crystal structures of seven of them were analysed by X-ray diffraction. The absorption spectra of these compounds are similar to those of their respective fluorophore groups (styrene or stilbene), showing a very small influence of the substituent (Me or Ph) linked to the second C atom or the cluster isomer (o- or m-). On the other hand, fluorescence spectroscopy revealed high emission intensities for Me-o-carborane derivatives, whereas their Ph-o-carborane analogues evidenced an almost total lack of fluorescence, confirming the significant role of the substituent bound to the adjacent C in o-carboranes. In contrast, all the m-carborane derivatives display similar photoluminescence (PL) behavior regardless of the substituent attached to the second C, demonstrating its small influence on emission properties. Additionally, m-carborane derivatives are significantly more fluorescent than their o-counterparts, reaching quantum yield values as high as 30.2%. Regarding solid state emission, only stilbene-containing Ph-o-carborane derivatives, which showed very low fluorescence in solution, exhibited notable PL emission in films attributed to aggregation-induced emission. DFT calculations were performed to successfully complement the photoluminescence studies, supporting the experimentally observed photophysical behavior of the styrene and stilbene-containing carborane derivatives. In conclusion, in this work it is proved that it is possible to tailor the PL properties of carborane-stilbene dyads by changing the C substituent and the carborane isomer.
本文介绍了两种新型的含苯乙烯的间碳硼烷衍生物，它们在第二个碳簇原子（C）上分别被甲基（Me）或苯基（Ph）取代，同时还介绍了一组新的含二苯乙烯的邻（o-）和间（m-）碳硼烷二元化合物。后一组化合物是通过含苯乙烯的碳硼烷衍生物经Heck偶联反应制备的。通过使用钯配合物[Pd(dba)]/[Pd(t-BuP)]作为催化体系，这些化合物实现了高区域选择性，仅生成E异构体。所有化合物均已得到充分表征，其中七种化合物的晶体结构通过X射线衍射进行了分析。这些化合物的吸收光谱与其各自的荧光团（苯乙烯或二苯乙烯）的吸收光谱相似，表明连接到第二个C原子的取代基（Me或Ph）或簇异构体（o-或m-）的影响非常小。另一方面，荧光光谱显示Me-o-碳硼烷衍生物具有高发射强度，而它们的Ph-o-碳硼烷类似物几乎完全没有荧光，这证实了连接到o-碳硼烷中相邻C的取代基的重要作用。相比之下，所有m-碳硼烷衍生物无论连接到第二个C的取代基如何，都表现出相似的光致发光（PL）行为，表明其对发射性质的影响较小。此外，m-碳硼烷衍生物的荧光明显强于其o-对应物，量子产率高达30.2%。关于固态发射，只有含二苯乙烯的Ph-o-碳硼烷衍生物在溶液中荧光非常低，但在薄膜中表现出显著的PL发射，这归因于聚集诱导发射。进行了密度泛函理论（DFT）计算，以成功补充光致发光研究，支持实验观察到的含苯乙烯和二苯乙烯的碳硼烷衍生物的光物理行为。总之，在这项工作中证明，通过改变C取代基和碳硼烷异构体，可以调整碳硼烷-二苯乙烯二元化合物的PL性质。
