Analytical and preparative enantioseparation and main chiroptical properties of Iridium(III) bis(4,6-difluorophenylpyridinato)picolinato.
Almost all Iridium(III) complexes employed both as dopants in PhOLEDs and as pharmaceuticals and fluorescence bioprobes are racemic mixtures. In this study the single enantiomers of the most stable diastereomeric 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 into stable optically active Λ and Δ isomers employing cellulose based chiral stationary phase both in normal and polar phase mode. Their chirality was confirmed and their absolute configuration assigned employing several methods (DFT and TDDFT calculations, CD and VCD). The CPL spectroscopy of the isolated enantiomers of FIrpic was also recorded due to its possible value in the OLEDs field. The chromatographic method was applied for a semipreparative purpose demonstrating that polar organic solvent chromatography (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 thermal stress by liquid chromatography coupled to high-resolution mass spectrometry (LC-QTOF) on both chiral and achiral columns. No racemization and/or isomerization was observed; however, the dissociation of the ancillary ligand was demonstrated employing LC-QTOF.
Department of Biological and Environmental Sciences and Technologies, University of Salento, Via per Monteroni, 73100 Lecce, Italy; CNR-NANOTEC, Campus Ecotekne of the University of Salento, Via per Monteroni, 73100 Lecce, Italy.
Cinzia
C
Citti
Department of Life Sciences, University of Modena & Reggio Emilia, Via Campi 103, 41125 Modena, Italy; Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University, Richmond, VA 23298, United States.
Umberto M
UM
Battisti
Department of Biological and Environmental Sciences and Technologies, University of Salento, Via per Monteroni, 73100 Lecce, Italy; CNR-NANOTEC, Campus Ecotekne of the University of Salento, Via per Monteroni, 73100 Lecce, Italy.
Giuseppe
G
Ciccarella
CNR-NANOTEC, Campus Ecotekne of the University of Salento, Via per Monteroni, 73100 Lecce, Italy.
Vincenzo
V
Maiorano
CNR-NANOTEC, Campus Ecotekne of the University of Salento, Via per Monteroni, 73100 Lecce, Italy.
Giuseppe
G
Gigli
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy; CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Via della Vasca Navale, 84, 00146 Roma, Italy.
Sergio
S
Abbate
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy.
Giuseppe
G
Mazzeo
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy; JASCO Europe, Via Cadorna 1, 23894 Cremella, LC, Italy.
Ettore
E
Castiglioni
Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy; CNISM Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Via della Vasca Navale, 84, 00146 Roma, Italy. Electronic address: giovanna.longhi@unibs.it.
Giovanna
G
Longhi
CNR-NANOTEC, Campus Ecotekne of the University of Salento, Via per Monteroni, 73100 Lecce, Italy; Department of Life Sciences, University of Modena & Reggio Emilia, Via Campi 103, 41125 Modena, Italy. Electronic address: giuseppe.cannazza@unimore.it.
Giuseppe
G
Cannazza
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002942:Circular Dichroism; D056831:Coordination Complexes / Q000737:chemistry* / Q000302:isolation & purification; D007495:Iridium; D008024:Ligands; D013237:Stereoisomerism
D056831:Coordination Complexes; D008024:Ligands; C000612961:ridium(III) bis(4,6-difluorophenylpyridinato)picolinato; D007495:Iridium
Absolute configuration; Chemical stability; Chiral chromatography; FIrpic; Stereochemical stability