tAlmost all Iridium(III) complexes employed both as dopants in PhOLEDs and as pharmaceuticals andfluorescence bioprobes are racemic mixtures. In this study the single enantiomers of the most stablediastereomeric form fac-trans-N–N, bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III)(FIrpic) were separated and analysed. The data obtained showed that the complex can be separated intostable optically active and isomers employing cellulose based chiral stationary phase both in normaland polar phase mode. Their chirality was confirmed and their absolute configuration assigned employ-ing several methods (DFT and TDDFT calculations, CD and VCD). The CPL spectroscopy of the isolatedenantiomers of FIrpic was also recorded due to its possible value in the OLEDs field. The chromatographicmethod was applied for a semipreparative purpose demonstrating that polar organic solvent chromatog-raphy (POSC) could be used to avoid the low-solubility issues associated with these Iridium(III) complexes.Finally, the chemical and stereochemical stability of the single isomers was evaluated under thermalstress by liquid chromatography coupled to high-resolution mass spectrometry (LC-QTOF) on both chiraland achiral columns. No racemization and/or isomerization was observed; however, the dissociation ofthe ancillary ligand was demonstrated employing LC-QTOF.

Analytical and preparative enantioseparation and main chiroptical properties of Iridium(III) bis(4,6-difluorophenylpyridinato)picolinato

ABBATE, Sergio;MAZZEO, Giuseppe;LONGHI, Giovanna
;
2016-01-01

Abstract

tAlmost all Iridium(III) complexes employed both as dopants in PhOLEDs and as pharmaceuticals andfluorescence bioprobes are racemic mixtures. In this study the single enantiomers of the most stablediastereomeric form fac-trans-N–N, bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III)(FIrpic) were separated and analysed. The data obtained showed that the complex can be separated intostable optically active and isomers employing cellulose based chiral stationary phase both in normaland polar phase mode. Their chirality was confirmed and their absolute configuration assigned employ-ing several methods (DFT and TDDFT calculations, CD and VCD). The CPL spectroscopy of the isolatedenantiomers of FIrpic was also recorded due to its possible value in the OLEDs field. The chromatographicmethod was applied for a semipreparative purpose demonstrating that polar organic solvent chromatog-raphy (POSC) could be used to avoid the low-solubility issues associated with these Iridium(III) complexes.Finally, the chemical and stereochemical stability of the single isomers was evaluated under thermalstress by liquid chromatography coupled to high-resolution mass spectrometry (LC-QTOF) on both chiraland achiral columns. No racemization and/or isomerization was observed; however, the dissociation ofthe ancillary ligand was demonstrated employing LC-QTOF.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11379/488032
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