Vinylene-Bridged Cyclic Dipyrrin and BODIPY Trimers

Int J Mol Sci. 2020 Oct 28;21(21):8041. doi: 10.3390/ijms21218041.

Abstract

Vinylene-bridged cyclic boron-difluoride complex of dipyrrin (BODIPY) trimers were successfully prepared from expanded dimethyl-vinylene bridged hexaphyrin(2.1.2.1.2.1) Me-Hex that has the structure of alternate dipyrrins and vinylene bridges. The hexaphyrin(2.1.2.1.2.1) Me-Hex can coordinate with boron ions to afford five kinds of cyclic BODIPYs given by step-by-step boron complexations. Crystal structures of all cyclic BODIPYs except for 3BF2-Me-Hex(b) formed non-planar structures. The theoretical calculation predicted that mono-/bis-boron cyclic BODIPYs show the intramolecular charge transfer (ICT) characteristics, whereas tri-boron cyclic BODIPYs have no ICT characteristics. Reflecting these electronic properties, tri-boron cyclic BODIPYs exhibit weak fluorescence in the red region, but mono-/bis-boron cyclic BODIPYs exhibit no emission. Vinylene bridged cyclic dipyrrin trimer Me-Hex is the novel porphyrinoid ligand allowed to control the boron coordination under different reaction conditions to form various boron complexes.

Keywords: boron complex; expanded porphyrin; molecular configuration.

MeSH terms

  • Boron Compounds / chemistry*
  • Crystallography, X-Ray
  • Dioxoles / chemistry*
  • Fluorescence*
  • Fluorescent Dyes / chemistry*
  • Models, Molecular
  • Molecular Structure

Substances

  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Boron Compounds
  • Dioxoles
  • Fluorescent Dyes
  • boron difluoride
  • vinylene carbonate