Tuning brightness and oxygen sensitivity of Ru(II) and Ir(III) luminophores


Ruggi, Albert (2011) Tuning brightness and oxygen sensitivity of Ru(II) and Ir(III) luminophores. thesis.

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Abstract:The design of luminophores with high brightness is of crucial importance for many
applications like the realization of Organic Light Emitting Diodes (OLEDs), and for
biomedical imaging. However, despite the great number of works dedicated to the definition
of the possible strategies for the realization of bright compounds, we are still far from a
"perfect" luminophore for biological applications. The design of highly bright luminophores
for biological imaging still constitutes a major challenge: the necessity of conjugating a high
brightness (the product of the quantum yield and the molar extinction coefficient) with a low
degree of oxygen quenching (which is necessary in order to keep a high luminescence in the
oxygen-rich bio-environment) is still an open problem. Semiconductor Quantum Dots (QDs)
are so far, the best candidates for biological applications since they show quantum yields
closed to the unity and low oxygen sensitivity. However, despite the brilliant performances
shown by QDs, their in vivo toxicity is still a major concern, especially from the perspective
of a human application.
Transition metal complexes are ideal candidates for the realization of bright luminophores,
considering their high stability in biological environment and the possibility of tuning their
optical properties by conveniently changing the structure of the ligands. Ruthenium(II) and
iridium(III) complexes, in particular, are among the most studied transition metal complexes
and the large amount of literature available makes them ideal candidates for further
improvement. Two possible strategies can be followed in order to improve the optical
properties of a luminophore: the decrease of its oxygen quenching degree and the
amplification of its brightness. The first strategy is quite promising especially in order to
improve the optical properties of Ir(III)-complexes, which show a pronounced oxygen
sensitivity. Conversely, the brightness amplification via multiple labelling is particularly
attractive for Ru(II)-complexes, which are barely sensitive to oxygen quenching but show
also a low emission quantum yield. In this thesis both strategies have been applied in order to
realise highly bright luminescent compounds based on Ru(II) or Ir(III) complexes. Moreover,
since there is only a limited amount of literature concerning the tunability of the oxygen
quenching of Ir(III)-complexes, a systematic study has been conducted in order to clarify the
structure-quenching relationship.
Item Type:Thesis
Science and Technology (TNW)
Research Group:
Link to this item:http://purl.utwente.nl/publications/77609
Official URL:https://doi.org/10.3990/1.9789036532013
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