Syntheses and spectroscopic properties of substituted diazaborepins with large stokes shift. Issue 22 (31st May 2018)

• Record Type: Journal Article
• Authors: Zhang, Tingting; Li, Yujiao; Yan, Jiaying; Liang, Ying; Xu, Binbin; Zheng, Kaibo; Zhang, Nuonuo
• Is Part Of: Tetrahedron. Volume 74:Issue 22(2018)
• Page Start: 2807
• Page End: 2811
• Publication Date: 2018-05-31
• Subjects: Diazaborepin -- BF2-chelated complex -- Seven-membered ring -- Solvatochromic effects -- Photophysical properties; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2018.04.063
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The substituted diazaborepins (DABs ) with halogen (Cl, Br), methoxyl and ethyl ester group on the fifth position of indole unit have large stokes shift, high fluorescence quantum yields and would be used in biomedicine. Their absorption and emission properties were studied in different solvents. Electron-withdrawing group tended to a bathochromic shift of the absorption and fluorescence probably due to its D-π-A structure. Solvatochromic effects were also studied based on Lippert-Mataga equation. DAB-5 with ethyl ester group exhibits more pronounced fluorescence solvatochromic effects than DAB-3 with Br group. The energy gap and simulated stick spectra of DABs based on Density Functional Theory (DFT) and Time-dependent Density Functional Theory (TD-DFT) calculation was obtained. Graphical abstract: Image 1 Highlights: The substituted, BF2 -chelated diazaborepins (DABs ) were synthesized. The DABs almost all exhibited large stokes shift (≥67 nm) in different solvents. DAB-5 exhibits more pronounced fluorescence solvatochromic effects than DAB-3.