Fiber optic lifetime pH sensing based on ruthenium(II) complexes with dicarboxybipyridine

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Helena M R Goncalves (Author) Other; Cesar D Maule (Author) Other; Pedro A S Jorge (Author) FCUP; Joaquim Esteves G E da Silva (Author) FCUP

Journal

Title: Analytica Chimica Acta

Vol. 626

Pages: 62-70

ISSN: 0003-2670

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 38 Citations

Scopus - 39 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-003-W5A

DOI: 10.1016/j.aca.2008.07.044

Abstract (EN): The complexes of ruthenium(II) with phenanthroline (Phen), diphenylphenanthroline (Ph(2)Phen) and with 4,4'-dicarboxy-2,2'-bipyridine acid (Dcbpy) ([Ru(Phen)(2)Dcbpy]Cl(2) and [Ru(Ph(2)Phen)(2)Dcbpy]Cl(2)) were synthesized and the variation of the correspondent fluorescence intensity and lifetime with the pH characterized, Luminescence Intensity, emission wavelength and excited state lifetime all show a typical sigmoid variation with pH in the range 3-9, demonstrating the suitability of this complex for luminescence sensing applications. In aqueous solutions (28% ethanol) the complexes [Ru(Phen)(2)Dcbpy]Cl(2) and [Ru(Ph2Phen)2Dcbpy]Cl2 show, respectively, the following properties: apparent pK(a) of 3.6 +/- 0.4 and 3.7 +/- 0.4; lifetimes of the protonated species 0.46 +/- 0.01 mu s and 0.38 +/- 0.02 mu s and ionised species 0.598 +/- 0.001 mu s and 0.61 +/- 0.08 mu s. The [Ru(Phen)(2)Dcbpy]Cl(2) complex was immobilised in the tip of optical fibers using a hybrid sol-gel procedure based on tetraethoxysilan and phenyltriethoxysilan enabling pH sensitive fiber probes. The immobilised complex shows the following lifetimes: protonated species 1.05 +/- 0.04 mu s and ionised species 1.16 +/- 0.04 mu s. These characteristics show that these ruthenium(II) complexes are good indicators for pH sensing, either in aqueous solution or immobilised in sol-gel, and are well suited for intensity and/or frequency domain interrogation.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9