Counter Anion Effect on the Photophysical Properties of Emissive Indolizine-Cyanine Dyes in Solution and Solid State

Molecules. 2018 Nov 22;23(12):3051. doi: 10.3390/molecules23123051.

Abstract

Near-infrared emissive materials with tunable Stokes shifts and solid-state emissions are needed for several active research areas and applications. To aid in addressing this need, a series of indolizine-cyanine compounds varying only the anions based on size, dipole, and hydrophilicity were prepared. The effect of the non-covalently bound anions on the absorption and emission properties of identical π-system indolizine-cyanine compounds were measured in solution and as thin films. Interestingly, the anion choice has a significant influence on the Stokes shift and molar absorptivities of the dyes in solution. In the solid-state, the anion choice was found to have an effect on the formation of aggregate states with higher energy absorptions than the parent monomer compound. The dyes were found to be emissive in the NIR region, with emissions peaking at near 900 nm for specific solvent and anion selections.

Keywords: NIR emissive materials; indolizine cyanine; optical materials; solid-state emission; stokes shift.

MeSH terms

  • Anions
  • Carbocyanines / chemistry*
  • Fluorescent Dyes / chemical synthesis*
  • Fluorescent Dyes / chemistry
  • Indolizines / chemical synthesis*
  • Indolizines / chemistry
  • Molecular Structure
  • Solvents
  • Spectroscopy, Near-Infrared

Substances

  • Anions
  • Carbocyanines
  • Fluorescent Dyes
  • Indolizines
  • Solvents