Microenvironment-switchable singlet oxygen generation by axially-coordinated hydrophilic ruthenium phthalocyanine dendrimers

Uwe Hahn, Francesca Setaro, Xavier Ragas, Angus Gray-Weale, Santi Nonell, Tomas Torres

Research output: Contribution to journalArticleResearchpeer-review

22 Citations (Scopus)

Abstract

A series of new metallodendrimers built around a ruthenium phthalocyanine core has been prepared. Employing a convergent synthetic strategy, pyridine-containing ligands were prepared and then assembled onto the ruthenium phthalocyanine through axial ligand coordination. The growing shell of oligoethylene glycol chains surrounding the lipophilic core allows solubilisation in water. Photophysical studies show that all the metallodendrimers are strongly phosphorescent and the deactivation pathway of their triplet state depends on the medium in which the compounds are dissolved. On one hand, quenching of the triplet state by the dendritic shell is observed and found to be substantially enhanced in aqueous media. On the other, the dendrimer shields the phthalocyanine from oxygen. This notwithstanding, the phthalocyanines are able to generate singlet oxygen in less polar environments such as in CHCl(3) or THF solution, while in water the generation of singlet oxygen is almost completely switched off.
Original languageEnglish
Pages (from-to)3385 - 3393
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume13
Issue number8
DOIs
Publication statusPublished - 2011

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