Synthesis of biocompatible near infrared phosphorescent complexes and their application in bioimaging as triplet oxygen sensors in live systems are still challenging areas of organometallic chemistry. We have designed and synthetized four novel iridium [Ir(NˆC) 2 (NˆN)] + complexes (NˆC–benzothienyl-phenanthridine based cyclometalated ligand; NˆN–pyridin-phenanthroimidazol diimine chelate), decorated with oligo(ethylene glycol) groups to impart these emitters’ solubility in aqueous media, biocompatibility, and to shield them from interaction with bio-environment. These substances were fully characterized using NMR spectroscopy and ESI mass-spectrometry. The complexes exhibited excitation close to the biological “window of transparency”, NIR emission at 730 nm, and quantum yields up to 12% in water. The compounds with higher degree of the chromophore shielding possess low toxicity, bleaching stability, absence of sensitivity to variations of pH, serum, and complex concentrations. The properties of these probes as oxygen sensors for biological systems have been studied by using phosphorescence lifetime imaging experiments in different cell cultures. The results showed essential lifetime response onto variations in oxygen concentration (2.0–2.3 µs under normoxia and 2.8–3.0 µs under hypoxia conditions) in complete agreement with the calibration curves obtained “in cuvette”. The data obtained indicate that these emitters can be used as semi-quantitative oxygen sensors in biological systems.

Original languageEnglish
Article number2898
Number of pages22
JournalMolecules
Volume26
Issue number10
DOIs
StatePublished - 13 May 2021

    Research areas

  • Ir(III) complexes, NIR emitters, Oxygen sensing, Phosphorescence lifetime imaging, Biocompatible Materials/chemistry, Cricetulus, Humans, Molecular Conformation, Iridium/chemistry, Luminescence, Subcellular Fractions/metabolism, Animals, Proton Magnetic Resonance Spectroscopy, Oxygen/analysis, HeLa Cells, CHO Cells, MITOCHONDRIA, oxygen sensing, CYCLOMETALATED PLATINUM(II), phosphorescence lifetime imaging, EMISSIVE BEHAVIOR, LUMINESCENT RHENIUM(I), CELLS, PHOTOPHYSICAL PROPERTIES, PROBES, NANOPARTICLES, IRIDIUM(III) POLYPYRIDINE COMPLEXES, IN-VIVO

    Scopus subject areas

  • Drug Discovery
  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Molecular Medicine
  • Physical and Theoretical Chemistry
  • Pharmaceutical Science
  • Organic Chemistry

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