Determination of the Relative Ligand Binding Strength in Heteroleptic Ir(III) Complexes by ESI-Q-TOF Tandem Mass Spectrometry
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Altuntas, Esra; Winter, Andreas; Baumgärtel, Anja; Paulus, Renzo M.; Ulbricht, Christoph; Crecelius, Anna; Risch, Nikolaus; Schubert, Ulrich S.
- Abstract:
- An electrospray ionization quadrupole time-of-flight mass spectrometer has been utilized to investigate the relative ligandbinding
strengths in a series of heteroleptic-charged iridium(III) complexes of the general formula [(C^N)2IrIII(S-tpy)](PF6) by
using variable collision energies. Collision-induced dissociation experiments were performed in order to study the stability
of the IrIII complexes that are, for instance, suitable phosphors in light-emitting electrochemical cells. The ratio of signal intensities
belonging to the fragment and the undissociated complex depends on the collision energy applied for the tandem mass spectra
(MS/MS) analysis. By defining the threshold collision energy and the point of complete complex dissociation, it is possible to
estimate the relative complex stabilities depending on the nature of the coordinated ligands [i.e. type of cyclometalating ligand
(C^N), substituents on the S-shaped terpyridine (S-tpy)]. The collision energy values differed as a function of the coordination
sphere of the IrIII centers.
- Year:
- 2012
- Type of Publication:
- Article
- Journal:
- Journal of Mass Spectrometry
- Volume:
- 47
- Pages:
- 37 - 43