In order to comparing and explaining the experimental infrared, electronic absorption and emission spectra of tris (4-methyl-1-(1-methyl-1H-benzo [d] imidazol-2-yl) −4H-benzo [d] imidazo[1,5-a]imidazol-3-yl) methyl (L6), density functional theory calculations were performed to systematically study the spectral properties of several species with different electronic states (L6⁺, L6 and HL6⁺), as well as the axial substituted derivative with methoxy group (L6-OCH₃). The main peaks in the vibrational, electronic absorption and emission spectra were assigned in detail. Roles of molecular electronic states and axial substitution on the spectral properties are revealed. The calculated spectra are compared with experimental results to distinguish the nature of L6 in crystal and solvent. This work combing experiment and theoretical calculations would be good example for clarifying molecular electronic states and, thus, promising the practice application of such kind of novel molecules.

中文翻译：

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Tris (4-methyl-1-(1-methyl-1H-benzo [d] imidazol-2-yl)-4H-benzo [d]imidazo[1,5-a]imidazol-的红外、电子吸收和发射光谱- 3-yl) 甲基：分子电子态和轴向取代的作用

为了比较和解释三(4-甲基-1-(1-甲基-1H-苯并[d]咪唑-2-基)-4H-苯并[d]咪唑[ 1,5-a]咪唑-3-基）甲基（L6），进行密度泛函理论计算以系统地研究具有不同电子态（L6 ⁺，L6 和HL6 ⁺）的几种物种的光谱特性，以及带有甲氧基的轴向取代衍生物 (L6-OCH ₃）。详细指定了振动、电子吸收和发射光谱中的主峰。揭示了分子电子态和轴向取代对光谱特性的作用。将计算出的光谱与实验结果进行比较，以区分 L6 在晶体和溶剂中的性质。这项结合实验和理论计算的工作将为阐明分子电子状态提供很好的例子，从而有望为此类新型分子的实践应用提供支持。