Department of Chemistry & Biochemistry and the Materials Science Institute, University of Oregon, Eugene, OR, USA.
Department of Physical Chemistry, University of Málaga, Málaga, Spain.
Nat Chem. 2018 Nov;10(11):1134-1140. doi: 10.1038/s41557-018-0133-5. Epub 2018 Sep 17.
Many qualitative structure-property correlations between diradical character and emerging molecular properties are known. For example, the increase of diradical character further decreases the singlet-triplet energy gap. Here we show that inclusion of thiophenes within a quinoidal polycyclic hydrocarbon imparts appreciable diradical character yet retains the large singlet-triplet energy gap, a phenomenon that has no precedent in the literature. The low aromatic character of thiophene and its electron-rich nature are the key properties leading to these unique findings. A new indenoindenodibenzothiophene scaffold has been prepared and fully characterized by several spectroscopies, magnetic measurements, solid-state X-ray and state-of-the-art quantum chemical calculations, all corroborating this unique dichotomy between the diradical input and the emerging magnetic properties. New structure-property relationships such as these are not only extremely important in the field of diradical chemistry and organic electronics, but also provide new insights into the versatility of π-electron chemical bonding.
已知许多自由基特征与新兴分子性质之间存在定性的结构-性质相关性。例如，自由基特征的增加进一步降低了单重态-三重态能隙。在这里，我们表明，将噻吩包含在准轮烯多环碳氢化合物内赋予了相当程度的自由基特征，但仍保留了较大的单重态-三重态能隙，这一现象在文献中尚无先例。噻吩的低芳香性及其富电子性质是导致这些独特发现的关键性质。已经制备了一种新的茚并[1,2-b]吲哚并[2,3-b]噻吩骨架，并通过多种光谱、磁性测量、固态 X 射线和最先进的量子化学计算进行了全面表征，所有这些都证实了自由基输入和新兴磁性之间的这种独特二分法。这样的新结构-性质关系不仅在自由基化学和有机电子学领域非常重要，而且还为π-电子成键的多功能性提供了新的见解。
