Double Heterohelicenes Composed of Benzo[<i>b</i>]- and Dibenzo[<i>b</i>,<i>i</i>]phenoxazine: A Comprehensive Comparison of Their Electronic and Chiroptical Properties

Heterohelicenes are potential materials in molecular electronics and optics because of their inherent chirality and various electronic properties originating from the introduced heteroatoms. In this work, we comprehensively investigated two kinds of double NO-hetero[5]­helicenes composed of 12H-benzo­[b]­phenoxazine (BPO) and 13H-dibenzo­[b,i]­phenoxazine (DBPO). These helicenes exhibit good electron-donor properties reflecting the electron-rich character of their monomers and were demonstrated to work as p-type semiconductors. The enantiomers of these helicenes show the largest class of dissymmetry factors for circularly polarized luminescence (CPL) (|gCPL| > 10–2) among helicenes reported to date. Interestingly, the signs of CPL are opposite for BPO and DBPO double helicenes of the same helicity. The origin of the large gCPL values and the inversion of the CPL sign was addressed by analysis of the transition electronic dipole moments and transition magnetic dipole moments based on TD-DFT calculations.杂螺烯（Heterohelicenes）因固有手性以及引入杂原子所赋予的多样电子特性，成为分子电子学与光学领域的潜在功能材料。本研究系统探究了两类由12H-苯并[b]吩恶嗪（BPO）和13H-二苯并[b,i]吩恶嗪（DBPO）构成的双N,O-杂[5]螺烯。这类螺烯展现出优异的给电子特性，这与其单体的富电子属性相符，且已被证实可作为p型半导体使用。此类螺烯的对映异构体在迄今报道的螺烯中，拥有最大范围的圆偏振发光（CPL）不对称因子（|gCPL| > 10⁻²）。值得注意的是，相同螺旋手性的BPO与DBPO双螺烯，其CPL信号符号恰好相反。本研究通过基于含时密度泛函理论（TD-DFT）的跃迁电偶极矩与跃迁磁偶极矩分析，阐明了大gCPL值的来源以及CPL信号符号反转的机制。