In this work,azulene is introduced into nano-graphene with coronene center to enhance the second-order nonlinear optical(NLO)properties.The sum-over-states(SOS)model based calcu-lations demonstrate that dipolar contributions are larger than octu-polar contributions to the static first hyperpolarizability(<β0>)in most nano-graphenes except those with high symmetry(e.g.,a C2v nano-graphene has octupolar contributions ΦJ=3 up to 59.0％of the<β0>).Nano-graphenes containing two parallel orientating azulenes(i.e.,Out-P and Out-Ps)have large dipole moments,while their ground state is triplet.Introducing B/N/BN atoms into the positions with a high spin density transfers the ground state of Out-P and Out-Ps to closed-shell singlet,and the Out-Ps-2N has a large<β0>of 1621.67×10-30 esu.Further addition of an electron donor(NH2)at the pentagon end enhances the<β0>to 1906.22×10-30 esu.The two-dimensional second-order NLO spectra predicted by using the SOS model find strong sum frequency generations and difference frequency generations,especially in the near-infrared and visible regions.The strategies to stabilize the electronic structure and improve the NLO properties of azulene-defect carbon nanomaterials are proposed,and those strategies to engineer nano-graphenes to be semiconducting while maintaining the π-framework are exten-dable to other similar systems.

CHEN Kaichun;ZHENG Xuelian;YANG Cuicui;TIAN Wei Quan;LI Weiqi;YANG Ling

Chongqing Key Laboratory of Theoretical and Computational Chemistry,College of Chemistry and Chemical Engineering,Chongqing University,Huxi Campus,Chongqing 401331,P.R.China;School of Physics,Harbin Institute of Technology,Harbin 150001,P.R.China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,P.R.China;MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage,Institute of Theoretical and Simulational Chemistry,School of Chemistry and Chemical Engineering,Harbin Institute of Technology,Harbin 150001,P.R.China

高等学校化学研究（英文版）

[1]CHEN Kaichun;ZHENG Xuelian;YANG Cuicui;TIAN Wei Quan;LI Weiqi;YANG Ling-.Theoretical Studies on the Electronic Structure of Nano-graphenes for Applications in Nonlinear Optics)[J].高等学校化学研究（英文版）,2022(02):579-587

graphenes,azulene,coronene,octu,hyperpolarizability,octupolar,orientating,azulenes,dable

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