Charge-Transfer Character Drives Mobius Antiaromaticity in the Excited Triplet State of Twisted [28]Hexaphyrin
Charge-Transfer Character Drives Mobius Antiaromaticity in the Excited Triplet State of Twisted [28]Hexaphyrin
复制标题
DOI：
10.1021/acs.jpclett.8b00740
复制
发表时间：
2018-05-17
影响因子：
5.7
通讯作者：
Kobori, Yasuhiro
中科院分区：
文献类型：
--
作者：
Ema, Fumitoshi;Tanabe, Mana;Kobori, Yasuhiro
Mobius芳香族分子由于其轨道环共轭沿着扭曲Mobius拓扑结构而成为新型功能材料的研究热点。为了研究Mobius芳香族[28]六卟啉的最低激发三重态（T-1）的电子性质，我们采用时间分辨电子顺磁共振（TREPR）方法，在77 K下进行了磁光选择测量. EPR参数的分析表明，T-1态具有分子内电荷转移（CT）特性和位于Mobius带环一侧的局域激发特性。我们还证明了正交未配对轨道之间的CT字符触发快速三重态失活的自旋轨道耦合。这种失活可以是一个重要的晴雨表，以代表“反芳香性”，因为正交CT字符和不稳定性之间的连接，在T-1状态的削弱自旋-自旋交换耦合。
Mobius aromatic molecules have attracted great attention as new functional materials because of their it-orbital cyclic conjugations lying along the twisted Mobius topology. To elucidate the electronic character of the lowest excited triplet (T-1) state of a Mobius aromatic [28]hexaphyrin, we employed a time-resolved electron paramagnetic resonance (TREPR) method with applied magnetophotoselection measurements at 77 K. Analyses of the EPR parameters have revealed that the T-1 state possesses intramolecular charge-transfer (CT) character together with local excitation character residing at one side in the Mobius strip ring. We have also demonstrated that the CT character between orthogonal unpaired orbitals triggers quick triplet deactivation by spin-orbit coupling. This deactivation can be an important barometer to represent the "antiaromaticity" because of a connection between the orthogonal CT character and instability by a weakened spin-spin exchange coupling in the T-1 state.