Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.524039
Title: New luminescent iridium (III) complexes containing NCN cyclometallated ligands : synthesis, photophysical properties and emission tuning
Author: Brulatti, Pierpaolo
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2010
Availability of Full Text:
Access from EThOS:
Access from Institution:
Abstract:
The luminescence properties of cyclometallated iridium(III) complexes render them of interest, for example, as phosphorescent dopants in organic light-emitting devices (OLEDs), as photoactive units in solar energy conversion, and as biosensors. The vast majority comprise three bidentate ligands, archetypal examples being Ir(ppy)3 and [Ir(ppy)2(bpy)]+ (ppy = 2-phenylpyridine; bpy = 2,2'- bipyridine). The work described here explores the chemistry of iridium(III) complexes that contain a terdentate cyclometallating ligand. Most of the complexes studied have the general formula Ir(N^C^N)(N^C)X, where N^C^N represents a terdentate ligand based on 1,3-di(2-pyridyl)benzene; N^C a bidentate ligand such as ppy; and X is a monodentate ligand such as chloride, cyanide, thiocyanate or an acetylide. The synthetic methodology developed involves reaction of the N^CH^N proligand with iridium(III) chloride to give a dimer of the form [Ir(N^C^N)Cl(-Cl)]2, which is cleaved upon treatment with a bidentate N^CH ligand. The one remaining chloride ligand can then be exchanged for other monodentate ligands through silvercatalysed metathesis. Most of these complexes are highly luminescent, with quantum yields in degassed dichloromethane at room temperature between 0.2 and 0.9. The effect of substituents in both the aryl and pyridyl rings of the terdentate and bidentate ligands has been investigated, together with the influence of X. The emission energy has been shown to vary over a very wide range, from the blue to red regions (max = 456 to 667 nm). The trends have been partially rationalised using time-dependent density functional theory and cyclic voltammetry. Some complexes have been incorporated into multi-layer OLEDs that display unusually high efficiency, particularly for the red-emitting devices. Selected rhodium(III) analogues have been prepared, together with related iridium(III) complexes incorporating bidentate N^N (bpy) ligands. A preliminary investigation into the utility of these complexes for the construction of multimetallic assemblies has been made, through the introduction of bridging ligands into position X.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.524039  DOI: Not available
Share: