文献类型：期刊文献

英文题名：Interplay of Steric Effects and Aromaticity Reversals to Expand the Structural/Electronic Responses of Dihydrophenazines

作者：Jin, Xin[1,2];Li, Sifan[1,2];Guo, Lifang[1,2];Hua, Jianli[1,2];Qu, Da-Hui[1,2];Su, Jianhua[1,2];Zhang, Zhiyun[1,2];Tian, He[1,2]

机构：[1]East China Univ Sci & Technol, Frontiers Sci Ctr Mat & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Key Lab Adv Mat, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Frontiers Sci Ctr Mat & Dynam Chem, Feringa Nobel Prize Scientist Joint Res Ctr, Joint Int Res Lab Precis Chem & Mol Engn, Shanghai 200237, Peoples R China

年份：2022

卷号：144

期号：11

起止页码：4883

外文期刊名：JOURNAL OF THE AMERICAN CHEMICAL SOCIETY

收录：;EI(收录号：20221211820274);WOS:【SCI-EXPANDED(收录号:WOS:000777169400025)】；

基金：This work was supported by NSFC/China (21788102, 22175063, 21905090, and 21790361), Shanghai Municipal Sci. & Tech. Major Project (2018SHZDZX03), the 111 Project (B16017), Shanghai Committee of Sci. & Tech. (17520750100), Natural Science Foundation of Shanghai (19ZR1412200), and the Program for Eastern Scholar Distinguished Professor. Z.Z. thanks Prof. J. Q. Chen and M. Lv for the measurements of the femtosecond transient absorption spectra. Z.Z. dedicates this paper to Prof. P.-T. Chou on the occasion of his 65th birthday.

语种：英文

外文关键词：Aromatization - Red Shift - Excited states - Musculoskeletal system

摘要：To gain insights into the coupling of conformationaland electronic variables, we exploited steric hindrance to modulate apolycyclic skeleton with a bent conformation in the S0state and atwisted conformation in the S1stateundertheguidanceofphotoexcited aromaticity reversals. Polycyclic 5,10-dihydrophenazine(DHP) adopted a bent structure in S0but involved a bent-to-planartransformation in S1due to the excited-state aromaticity of the 8 pi-electron central ring. TheN,N '-locations and 1,4,6,9-sites of theDHPskeleton provided a versatile chemical handle forfine-tuningintramolecular steric hindrance. Specifically,N,N '-diphenyl-5,10-dihydrophenazine (DPP-00) and its derivativesDPP-10-DPP-22were synthesized with different numbers of methyl groups on the1,4,6,9-sites. X-ray crystal analyses suggested that theDHPskeletonsofDPP-00-DPP-22had more bending configurations along the NmiddotmiddotmiddotN axis with an increase in the number of methyl groups. Following the bending-promoted interruption of pi-conjugation, theabsorption spectra ofDPP-00-DPP-22significantly blue-shifted from 416 to 324 nm. By contrast, the emission bands exhibited areverse shift to longer wavelengths from 459 to 584 nm as the number of methyl substituents increased. Theoretical calculationsrevealed that introducing methyl groups caused the planarDHPskeleton in S1to further twist along the NmiddotmiddotmiddotN axis, resulting in atwisted high-strain conformation. The greater Stokes shift of the more steric-hindered structure can be attributed to the release oflarger strain and aromatic stabilization energy. This research highlighted the potential promise associated with the interplay of stericeffects and aromaticity reversals in a singlefluorophore.