Crucial Factors Regulating Intramolecular Charge-Transfer-Based Radiative Efficiency in <i>ortho</i>-Carboranyl Luminophores: Planarity between Substituted Biphenyl Rings

o-Carboranyl compounds contain specific geometries, ranging from planar to orthogonally distorted biphenyl rings. Herein, 13 o-carboranyl compounds, 1HF–13PP, were synthesized and fully characterized to determine the impact of structural formation of the aromatic group appended with the o-carborane to estimate the efficiency of their radiative decay process. All the compounds exhibited significant intramolecular charge transfer (ICT)-based emission in the crystalline state at 298 K. Remarkably, increasing the distorted dihedral angles between biphenyl rings gradually decreased the emission efficiencies. Furthermore, their radiative decay constants decreased linearly with increasing dihedral angles, which demonstrated the inversely proportional relationship between these two factors. These findings distinctly suggest that the planar or distorted geometry of substituted aryl groups can strongly affect the efficiency of the ICT-based radiative process in o-carboranyl luminophores.邻碳硼烷化合物（o-Carboranyl compounds）具有特定的几何构型，涵盖从平面型到正交扭曲的联苯环结构。本文中，研究人员合成了1HF–13PP共计13种邻碳硼烷化合物并完成全面表征，旨在探究连有邻碳硼烷（o-carborane）的芳香基团的结构形成对其辐射衰变过程效率的影响。所有化合物在298 K的晶态下均表现出显著的分子内电荷转移（intramolecular charge transfer, ICT）型发光。值得注意的是，联苯环之间的扭曲二面角逐渐增大时，发光效率逐步降低。此外，辐射衰变常数随二面角增大呈线性降低，证实了二者之间呈反比关系。本研究结果明确表明，取代芳基的平面或扭曲几何构型可显著影响邻碳硼烷发光体中ICT型辐射过程的效率。