Cyclometalated Iridium(III) Complex with Substituted Benzimidazole: pH Directed Organelle-Specific Localization Within Lysosome

Chembiochem. 2024 Dec 16;25(24):e202400597. doi: 10.1002/cbic.202400597. Epub 2024 Nov 4.

Abstract

We report the synthesis and pH dependent emission spectral behaviour of four emissive iridium(III) complexes (Ir1-Ir4) with two isomeric pairs of bis-trifluoromethyl appended benzimidazole ligands. The imidazolyl hydrogen(N-H) has been replaced by phenyl groups (N-Ph) in two ligands to understand the impact of hydrogen bonding on the photophysical properties of the complexes and it indeed plays interesting role in the charge-transfer dynamics. The pH dependent electronic spectral change is observed for two of the complexes. The enhancement of emission intensity is observed at different wavelength for pH<7 and pH>7 for Ir1 and Ir3. The emission sensing of biogenic amines with pka values ranging from 5.80-9.74 is reported along with cellular imaging. The complex Ir1 specifically localizes within lysosome (pH=4.5-5) and thus image this organelle with great precision. The detail electronic spectra and electrochemical behaviour were reported here along with TDDFT results.

Keywords: Emission; Histamine; Iridium; Lysosome; pH.

MeSH terms

  • Benzimidazoles* / chemistry
  • Coordination Complexes* / chemical synthesis
  • Coordination Complexes* / chemistry
  • Density Functional Theory
  • HeLa Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Iridium* / chemistry
  • Lysosomes* / chemistry
  • Lysosomes* / metabolism
  • Molecular Structure

Substances

  • Iridium
  • Benzimidazoles
  • Coordination Complexes
  • benzimidazole

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