Synthesis and Characterisation of New Cationic Fluorinated Iridium(III) Complexes via Quaternisation of Tetrazole-based Ancillary Ligands: A Convenient Approach for Fine-tuning Photophysical Properties and Antimicrobial Activity.

Authors

Amit Kumar, Praveen B Managutti, Rasha Wadia Mohd, Naiem Ahmad Wani, Navin Subba, Osama K Abou-Zied, Massimiliano Massi, Emilia Oueis, Janah Shaya, Andrew B Lowe

Published in

Chemistry (Weinheim an der Bergstrasse, Germany). Pages e71378. Jul 20, 2026. Epub Jul 20, 2026.

Abstract

Herein we report the synthesis and characterisation of heteroleptic cationic Ir(III) complexes, [Ir(ppy)₂(PyTz-R)][PF₆] and [Ir(ppy)₂(iQTz-R)][PF₆], (ppy: 2-phenylpyridine, PyTz: 2-(1H-tetrazol-5-yl)pyridine, iQTz: 1-(1H-tetrazol-5-yl)iso-quinoline and R: ─CH₃, ─CHF₂, ─CH₂CF₃ or ─CH₂Ph-p-CF₃). The parent Ir(ppy)₂(PyTz) and Ir(ppy)₂(iQTz) complexes were converted to the cationic derivatives by regiospecific tetrazole quaternisation adopting "chemistry-on-a-complex" and "ligand-first" approaches. Structures were confirmed by NMR/FTIR spectroscopies, mass spectrometry, and single-crystal X-ray crystallography. DFT was used to probe electronic changes upon quaternisation. Absorption spectra were broadly similar across all complexes (strong UV bands with weaker 300-450 nm MLCT features), whereas cationisation markedly altered emission: the neutral complexes showed vibronically structured emission (iQTz red-shifted vs PyTz), while all cationic derivatives displayed broad, structureless, further red-shifted profiles. The bathochromic shift increased with the electron-withdrawing strength of the R group (─CHF₂ > ─CH₂CF₃ > ─CH₂Ph-p-CF₃ ≈ ─CH₃). The photoluminescence quantum yields for the cationic complexes were determined to be in the range of 3.3-11.2%. The thermal stability of the complexes was evaluated by thermogravimetric analysis. Finally, the cationic complexes were qualitatively assessed for potential antimicrobial activity against E. coli and S. aureus, with activity observed against S. aureus in well-diffusion experiments.

PMID:
42478103
Bibliographic data and abstract were imported from PubMed on 21 Jul 2026.

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