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Title: Highly luminescent platinum complexes for light emitting devices and bio-imaging
Author: Murphy, Lisa
ISNI:       0000 0004 2687 4806
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2010
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Intensely luminescent cyclometallated platinum(II) complexes have been prepared containing N^C^N-coordinating ligands, based on 1,3-dipyridylbenzene. Exceptionally high quantum yields ( 0.85, degassed DCM, 298 K) are rationalised in terms of the particularly short Pt-C bond, which raises the energy of the normally deactivating d-d* state. Terdentate ligand functionalisation has been employed to obtain complexes with tuneable emission. Fluorination at the 3,5-aryl positions and/or placing electronreleasing substituents at the 4-pyridyl position gave complexes with blue-shifted emission, whilst retaining a high quantum yield. Substitution of the chloride ancillary ligand for cyanide led to further blue-shifts. In general, these complexes undergo intermolecular interactions in solutions of higher concentration to form excimers. The excimers are emissive in their own right, and display broad, structureless emission bands at lower energy than the isolated molecules (monomers). The influence of substituents in the terdentate ligand and the identity of the coligand on the energy and relative intensity of excimer emission has been elucidated. Some complexes have been used as phosphorescent dopants in the fabrication of high efficiency organic light emitting devices (OLED)s. The colour of a device depends on the monomer-to-excimer emission ratio, which is controlled by varying the dopant concentration. At intermediate concentrations, white OLEDs, with properties approaching pure white light, have been obtained. Preliminary investigations into the utility of the complexes as bio-imaging agents in live cells are reported. The complexes which contain small substituents on the terdentate ligand enter cells rapidly, retaining their phosphorescence. These Pt(II) complexes appear to localise simultaneously in both the nucleus and mitochondria of cells, where their emission characteristics differ: the application of appropriate filter sets allows separate visualisation of the two organelles. A selection of iridium(III) complexes were also investigated as bio-imaging agents. These complexes localise in cytoplasm-based organelles, and do not appear to enter the nucleus. Both classes of organometallic complexes are shown to be suitable candidates for time resolved emission imaging microscopy (TREM).
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available