Mayorga Burrezo Paula, Jiménez Vicente G, Blasi Davide, Ratera Imma, Campaña Araceli G, Veciana Jaume
Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB)/ CIBER-BBN, Campus Universitari de Bellaterra, E-08193, Cerdanyola, Barcelona, Spain.
Department of Organic Chemistry, University of Granada (UGR), C. U. Fuentenueva, 18071, Granada, Spain.
Angew Chem Int Ed Engl. 2019 Nov 4;58(45):16282-16288. doi: 10.1002/anie.201909398. Epub 2019 Sep 24.
Chiroptical properties of two chiral atropisomers of propeller-like trityl-based radical derivatives have been analyzed. A new absolute configuration (AC) assignment has been made, according to the combination of experimental and theoretical data. In this sense, their ACs have been determined through the comparison of the Cotton effects recorded by electronic circular dichroism (ECD) with the theoretical ECD of the open shell structures obtained by TD-DFT calculations. Finally, their circularly polarized luminescence (CPL) responses have been addressed. Remarkably, this is the first description of organic free radicals as intrinsic CPL emitters. Opposite signed CPL has been detected for each pair of conformers, with acceptable luminescent dissymmetry factors (|g |≈0.5-0.8×10 ) considering their pure organic nature. In fact, highly efficient chiral emissions have been demonstrated, according to the comparison of |g | with their respective absorption anisotropy factors (|g |). This pioneering study lays the foundations for the optimization of new magnetically active organic chiral emitters.
对螺旋桨状基于三芳基甲基的自由基衍生物的两种手性阻转异构体的手性光学性质进行了分析。根据实验和理论数据的结合，进行了新的绝对构型（AC）指定。从这个意义上说，通过将电子圆二色性（ECD）记录的科顿效应与通过TD-DFT计算获得的开壳结构的理论ECD进行比较，确定了它们的AC。最后，研究了它们的圆偏振发光（CPL）响应。值得注意的是，这是首次将有机自由基描述为内在CPL发射体。对于每一对构象异构体，都检测到了相反符号的CPL，考虑到它们的纯有机性质，发光不对称因子（|g|≈0.5-0.8×10）是可以接受的。事实上，根据|g|与其各自的吸收各向异性因子（|g|）的比较，已经证明了高效的手性发射。这项开创性的研究为新型磁活性有机手性发射体的优化奠定了基础。
