Unraveling the amplified chiroptical responses of rylene-bladed quintuple[6]helicenes

作     者：Yanan Wu Yujian Liu Wei Jiang Zhaohui Wang 

作者机构：Key Laboratory of Organic Optoelectronics and Molecular EngineeringDepartment of ChemistryTsinghua UniversityBeijing100084China 

出 版 物：《Science China Chemistry》 (中国科学（化学英文版）)

年 卷 期：2023年第66卷第8期

页      面：2400-2407页

核心收录：

学科分类：08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 

基　　金：supported by the National Natural Science Foundation of China(22122503,22235005,and 22275112) the Shandong Provincial Natural Science Foundation(ZR2019ZD50)。 

主　　题：chiral molecular carbon imides perylene diimides quintuple helicenes molecular symmetry chiroptical properties 

摘      要：Unraveling the key structural features to maximize the chiroptical properties is of significance for developing high-performance chiral materials.Here we present our first attempt to elucidate and understand the molecular design of excellent chiroptical properties via the combination of multiplicity and the alignment of subhelicenes.Two stereoisomeric PDI-bladed quintuple[6]helicenes,namely D_(5)-CRP and C_(2)-CRP,were revealed to show distinct spatial arrangements of subhelicenes.Circular dichroism(CD)spectra showed that the Cotton effects(Δε)are reaching 1,412 mol-1L cm-1for D_(5)-CRP and 669 mol^(-1)L cm^(-1)for C_(2)-CRP in the visible spectrum.The greatly amplifiedΔεrelative to the smaller analogue NPDH arises from the circular annulation of helicenes and high molecular symmetry that could significantly regulate the transition dipole moments and thereby make them tend to be(anti)parallel,as supported by TDDFT calculations for the rotatory strength(R).Consequently,the maximal dissymmetry factors(|g_(abs)|and|g_(lum)|)of this kind of chiral molecular carbon imides were estimated to be up to 0.021 and 0.012,respectively.This study provides a deep insight into the chiroptical properties of complicated chiral systems.