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Experimental and theoretical studies of pH-responsive iridium(III) complexes of azole and N-heterocyclic carbene ligands.
- Source :
-
Dalton transactions (Cambridge, England : 2003) [Dalton Trans] 2024 May 14; Vol. 53 (19), pp. 8478-8493. Date of Electronic Publication: 2024 May 14. - Publication Year :
- 2024
-
Abstract
- A series of nine luminescent iridium(III) complexes with pH-responsive imidazole and benzimidazole ligands have been prepared and characterized. The first series of complexes were of the form [Ir(ppy) <subscript>2</subscript> (N^N)] <superscript>+</superscript> or [Ir(ppy) <subscript>2</subscript> (C^N)] <superscript>+</superscript> (where ppy is 2-phenylpyridine and N^N is 2-(2-pyridyl)imidazole or 2-(2-pyridyl)benzimidazole and C^N represents a pyridyl-triazolylidene-based N-heterocyclic carbene ligand). For these complexes, the benzimidazole group was either unsubstituted or substituted with electron-withdrawing (Cl) or electron-donating (Me) groups. The second series of complexes were of the form [Ir(phbim) <subscript>2</subscript> (N^N)] <superscript>+</superscript> or [Ir(phbim) <subscript>2</subscript> (C^N)] <superscript>+</superscript> (where phbim is 2-phenylbenzimidazole and N^N is either 2,2'-bipyridine or 1,10-phenanthroline and C^N is either a pyridyl-imidazolylidene or pyridyl-triazolylidene N-heterocyclic carbene ligand). UV-visible and photoluminescence pH titration studies showed that changing the protonation state of these complexes results in significant changes in the photoluminescence emission properties. The p K <subscript>a</subscript> values of prepared complexes were estimated from the spectroscopic pH titration data and these values show that the nature of the pH-sensitive ligands (either main or ancillary ligands) resulted in a significant capacity to modulate the p K <subscript>a</subscript> values for these compounds with values ranging from 5.19-11.22. Theoretical investigations into the nature of the electronic transitions for the different protonation states of compounds were performed and the results were consistent with the experimental results.
Details
- Language :
- English
- ISSN :
- 1477-9234
- Volume :
- 53
- Issue :
- 19
- Database :
- MEDLINE
- Journal :
- Dalton transactions (Cambridge, England : 2003)
- Publication Type :
- Academic Journal
- Accession number :
- 38687288
- Full Text :
- https://doi.org/10.1039/d3dt03766e