厦门大学学报（自然科学版）2025，Vol.64Issue(5)：782-789,8.DOI:10.6043/j.issn.0438-0479.202404017
五吲哚心环烯衍生物位置异构体的合成及光电性质
Synthesis and photoelectric properties of pentaindolylcorannulene derivative positional isomers
摘要
Abstract
[Objective]Isomers are extensively prevalent in nature.Despite sharing the same molecular formula,they possess distinct molecular structures,resulting in diverse physical and chemical properties.In recent years,nitrogen-modified corannulene derivatives have attracted extensive research interest.However,the isomerization of azacorannulene derivatives has not been reported.Herein,we synthesized two different positional isomers of pentaindolylcorannulene derivatives 1 and 2 through modifying the edges of corannulene with different reaction sites of indole.Furthermore,we also studied the differences in their structures and properties.[Methods]The nucleophilic substitution reaction(SNAr)of 1,3,5,7,9-pentachlorocorannulene with indole was used to generate pentaindolylcorannulene derivative 1,and Suzuki coupling reaction of 1,3,5,7,9-pentakis(Bpin)corannulene with 7-bromoindole generated pentaindolylcorannulene derivative 2.Their molecular structures were characterized using matrix-assisted laser desorption ionization time-of-flight mass spectra(MALDI-TOF-MS)and nuclear magnetic resonance(NMR)spectroscopy.The photophysical properties were studied through ultraviolet-visible(UV-Vis)absorption and fluorescence emission spectra.The electrochemical properties were investigated by cyclic voltammetry,in conjunction with the theoretical calculation of frontier molecular orbital.[Results]Pentaindo-lylcorannulene derivatives 1 and 2 were respectively synthesized through one step five-fold nucleophilic substitution reaction and Suzuki coupling reaction.The molecular structures of compounds 1 and 2 with C5 symmetry were characterized by MS and NMR.UV-Vis absorption spectra showed that the maximum absorption wavelengths of compounds 1 and 2 were located at 368 and 354 nm,respectively,attributed to n-π*electron transitions.Based on the fluorescence decay curve,the fluorescence lifetimes of the two compounds were 0.54 and 3.62 ns,respectively.The fluorescence quantum yield of compound 1 was only 0.35％,while that of compound 2 reached 6.31％,approximately 18 times that of compound 1.The hydrogen bond between compound 2 and N,N-dimethylformamide(DMF)increased molecular rigidity,effectively inhibited non-radiative decay process after excitation,thereby prolonging fluorescence lifetime and enhancing fluorescence quantum yield.Cyclic voltammetry scan results revealed first oxidation potentials of 0.84 and 0.52 V for compounds 1 and 2,respectively.This indicates that the highest occupied molecular orbital(HOMO)energies were-5.64 and-5.32 eV,respectively.Consequently,compound 2 displayed a higher susceptibility to oxidation than compound 1.Theoretical calculation of molecular frontier orbit showed that the HOMO level and the lowest unoccupied molecular orbital(LUMO)level of compounds 1 and 2 were separated.The HOMO level was predominantly localized on the indole group,while the LUMO level was distributed across the central corannulene skeleton.Furthermore,theoretical calculations confirmed that compound 2 exhibited greater electron-donating propensity than compound 1.[Conclusion]The molecular structure of compound 1 with C-N bond modification is more conjugated,leading to a red shift in its absorption and emission wavelengths.Due to the hydrogen bond between compound 2 and DMF,the solubility of compound 2 is poor in organic solvents.The formation of these hydrogen bonds enhances molecular rigidity,effectively suppressing non-radiative decay process following excitation,thereby extending fluorescence lifetime and increasing fluorescence quantum yield.Compound 2 has a higher HOMO energy than compound 1,indicating a tendency to lose electrons more easily.This study provides valuable insights into the isomerization of corannulene derivatives.关键词
位置异构体/心环烯衍生物/吲哚Key words
positional isomer/corannulene derivative/indole分类
化学化工引用本文复制引用
吴学苗,申立春,张前炎,谢素原..五吲哚心环烯衍生物位置异构体的合成及光电性质[J].厦门大学学报（自然科学版）,2025,64(5):782-789,8.基金项目
国家自然科学基金(22271238) （22271238）
