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Synthesis and Characterizations of 5,5′-Bibenzo[rst]pentaphene with Axial Chirality and Symmetry-Breaking Charge Transfer
Advanced Science ( IF 14.3 ) Pub Date : 2022-02-13 , DOI: 10.1002/advs.202200004 Xiushang Xu 1, 2 , Suman Gunasekaran 3 , Scott Renken 3 , Lorenzo Ripani 4 , Dieter Schollmeyer 5 , Woojae Kim 3 , Massimo Marcaccio 4 , Andrew Musser 3 , Akimitsu Narita 1, 2
Advanced Science ( IF 14.3 ) Pub Date : 2022-02-13 , DOI: 10.1002/advs.202200004 Xiushang Xu 1, 2 , Suman Gunasekaran 3 , Scott Renken 3 , Lorenzo Ripani 4 , Dieter Schollmeyer 5 , Woojae Kim 3 , Massimo Marcaccio 4 , Andrew Musser 3 , Akimitsu Narita 1, 2
Affiliation
Exploration of novel biaryls consisting of two polycyclic aromatic hydrocarbon (PAH) units can be an important strategy toward further developments of organic materials with unique properties. In this study, 5,5′-bibenzo[rst]pentaphene (BBPP) with two benzo[rst]pentaphene (BPP) units is synthesized in an efficient and versatile approach, and its structure is unambiguously elucidated by X-ray crystallography. BBPP exhibits axial chirality, and the (M)- and (P)-enantiomers are resolved by chiral high-performance liquid chromatography and studied by circular dichroism spectroscopy. These enantiomers have a relatively high isomerization barrier of 43.6 kcal mol−1 calculated by density functional theory. The monomer BPP and dimer BBPP are characterized by UV-vis absorption and fluorescence spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. The results indicate that both BPP and BBPP fluoresce from a formally dark S1 electronic state that is enabled by Herzberg–Teller intensity borrowing from a neighboring bright S2 state. While BPP exhibits a relatively low photoluminescence quantum yield (PLQY), BBPP exhibits a significantly enhanced PLQY due to a greater S2 intensity borrowing. Moreover, symmetry-breaking charge transfer in BBPP is demonstrated by spectroscopic investigations in solvents of different polarity. This suggests high potential for singlet fission in such π-extended biaryls through appropriate molecular design.
中文翻译:
具有轴向手性和对称破坏电荷转移的 5,5'-二苯并[rst]五苯的合成和表征
探索由两个多环芳烃(PAH)单元组成的新型联芳基化合物可能是进一步开发具有独特性能的有机材料的重要策略。在这项研究中,以高效且通用的方法合成了具有两个苯并[ rst ]戊二烯 (BPP) 单元的5,5'-联苯并[ rst ]戊二烯 (BBPP) ,其结构通过 X 射线晶体学明确阐明。BBPP具有轴向手性,( M )-和( P )-对映体通过手性高效液相色谱分离,并通过圆二色光谱研究。这些对映体具有 43.6 kcal mol -1的相对较高的异构化屏障由密度泛函理论计算。单体BPP和二聚体BBPP通过紫外-可见吸收和荧光光谱、循环伏安和飞秒瞬态吸收光谱进行表征。结果表明,BPP 和 BBPP 都从形式上暗的 S 1 电子态发出荧光,这是由 Herzberg-Teller 强度从相邻的亮 S 2态借来的。虽然 BPP 表现出相对较低的光致发光量子产率 (PLQY),但由于更大的 S 2强度借用,BBPP 表现出显着增强的 PLQY。此外,通过对不同极性溶剂的光谱研究证明了 BBPP 中的对称破坏电荷转移。这表明在这种π中单线态裂变的可能性很高-通过适当的分子设计扩展联芳基。
更新日期:2022-02-13
中文翻译:
具有轴向手性和对称破坏电荷转移的 5,5'-二苯并[rst]五苯的合成和表征
探索由两个多环芳烃(PAH)单元组成的新型联芳基化合物可能是进一步开发具有独特性能的有机材料的重要策略。在这项研究中,以高效且通用的方法合成了具有两个苯并[ rst ]戊二烯 (BPP) 单元的5,5'-联苯并[ rst ]戊二烯 (BBPP) ,其结构通过 X 射线晶体学明确阐明。BBPP具有轴向手性,( M )-和( P )-对映体通过手性高效液相色谱分离,并通过圆二色光谱研究。这些对映体具有 43.6 kcal mol -1的相对较高的异构化屏障由密度泛函理论计算。单体BPP和二聚体BBPP通过紫外-可见吸收和荧光光谱、循环伏安和飞秒瞬态吸收光谱进行表征。结果表明,BPP 和 BBPP 都从形式上暗的 S 1 电子态发出荧光,这是由 Herzberg-Teller 强度从相邻的亮 S 2态借来的。虽然 BPP 表现出相对较低的光致发光量子产率 (PLQY),但由于更大的 S 2强度借用,BBPP 表现出显着增强的 PLQY。此外,通过对不同极性溶剂的光谱研究证明了 BBPP 中的对称破坏电荷转移。这表明在这种π中单线态裂变的可能性很高-通过适当的分子设计扩展联芳基。