IJUP08 - Universidade do Porto

Steady state and lifetime chemical sensors based on Ruthenium
complexes
Luminescence Intensity (a.u.)
Helena Gonçalves 1 , Joaquim C.G. Esteves da Silva 1 , César Maule 2
and Pedro Jorge 2
1 Department of Chemistry, CIQ-UP, Faculty of Sciences, University of Porto, Portugal.
2 Optoelectronics Unit of INESC Porto, Department of Physics, University of Porto, Portugal.
In recent years molecular recognition and supramolecular host-guest interaction have
attracted much attention [1]. The design of highly selective and sensitive receptors for
metal ions is of great importance in the area of ion transport, chemosensing, biomedical
and environmental applications, especially if the sensor is portable, allowing in situ
measurements. Ru(II) complexes with α-diimine ligands are particularly suited for
luminescence based sensing due to their high quantum yields, long lifetimes and
compatibility with low cost optoelectronics.
In this communication the results of two Ru(II) complexes will be presented. The
first complex, (Ru(Phen)2Dcbpy)Cl2, is constituted by the ligands 1,10-phenantroline
(Phen) and 2,2’-bipyridine-4,4’-dicarboxilic acid (Dcbpy) and the second complex,
(Ru(Ph2phen)2Dcbpy)Cl2, has 4,7-difenil-1,10-Fenantrolina (Ph2phen) and 2,2’-bipyridine-
4,4’-dicarboxilic acid (Dcbpy), which are pH sensitive. It was found that the first complex
has a pKa of 3 and an operation range of 2.5 pH units. Its lifetime at the pKa was τpka=
325 ns changing by ≈172 ns over the full operation range, which is well suited for
frequency domain interrogation (Fig. 1). For the complex second complex it was
determined a pKa of 2 and a range of 2.5 pH units was observed. Its τpka was 470 ns
changing by ≈160 ns over the whole operation range.
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Fig. 1 - Intensity (•) and peak wavelength (°) pH titration curves obtained for (Ru(Phen)2Dcbpy)Cl2
complex.
Acknowledgements: Financial support from Fundação para a Ciência e Tecnologia (Lisboa) (FSE-
FEDER) (Project POCTI/QUI/44614/2007) is acknowledged.
References:
[1] Clarke Y., Xu W., Demas J.N. and DeGraff B. (2000), Lifetime-Based pH sensor system based
on a polymer-supported Ruthenium(II) complex, 72 (15), 3468-3475.
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Peak wavelength (nm)
142