Abstract

By introducing phenyl, 1-naphtyl, 2-thienyl, 2-furanyl and 3-pyridyl rings into 4,7-di(thiophene-2-yl)-benzo[c][2,1,5]thiadiazole structure 2, five new asymmetric derivatives were prepared. For these compounds, HOMO/LUMO and gap energy levels were estimated by UV-Vis and cyclic voltammetry experiments in aprotic solvents. The results showed significant effects of aryl groups on gap data, were this parameter was mainly tuned by changes in the HOMO level of structure 2. These properties were examined also by electronic structure calculations and the estimations obtained described the experimental trends. Quantum chemical modeling exhibited homogeneous distribution of HOMO and LUMO energy levels in all studied compounds and suggest that planarity in the system is crucial to diminish the gap. The calculations also explain that, a conformational change (predicting a 54.2° dihedral angle between the 1-naphtyl substituent and the rest of the molecule) was responsible for the unexpected increase in gap of compound bearing a 1-naphtyl substituent; the latter phenomenon was corroborated by X-Ray information, which reveals a dihedral angle of 46.8°.

摘要

通过将苯基、1-萘基、2-噻吩基、2-呋喃基和 3-吡啶基环引入 4,7-二(噻吩-2-基)-苯并[c][2,1,5]噻二唑结构2 , 五制备了新的不对称衍生物。对于这些化合物，HOMO/LUMO 和间隙能级通过 UV-Vis 和非质子溶剂中的循环伏安实验进行估计。结果表明芳基对间隙数据有显着影响，这些参数主要通过结构2的 HOMO 能级的变化来调整. 还通过电子结构计算检查了这些特性，并且获得的估计描述了实验趋势。量子化学模型显示所有研究化合物中 HOMO 和 LUMO 能级的均匀分布，并表明系统中的平面性对于缩小间隙至关重要。计算还解释说，构象变化（预测 1-萘基取代基与分子其余部分之间的二面角为 54.2°）是导致带有 1-萘基取代基的化合物间隙意外增加的原因；后一种现象得到了 X 射线信息的证实，该信息揭示了 46.8° 的二面角。