Microenvironment-switchable singlet oxygen generation by axially-coordinated hydrophilic ruthenium phthalocyanine dendrimers
作者:Uwe Hahn、Francesca Setaro、Xavier Ragàs、Angus Gray-Weale、Santi Nonell、Tomas Torres
DOI:10.1039/c0cp01015d
日期:——
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 CHCl3 or THF solution, while in water the generation of singlet oxygen is almost completely switched off.
一系列以钌酞菁核心为基础的新金属树枝状聚合物已经被制备。采用汇聚合成策略,制备了含有吡啶的配体,然后通过轴向配体配位将其组装到钌酞菁上。围绕亲脂性核心生长的低聚乙烯醇链的外壳使其在水中能够溶解。光物理研究表明,所有金属树枝状聚合物都具有强烈的磷光,其三重态的去激发途径取决于化合物溶解的介质。一方面,观察到树枝状聚合物外壳对三重态的猝灭,且在水相中的猝灭效果显著增强。另一方面,树枝状聚合物能够屏蔽酞菁免受氧气的影响。尽管如此,酞菁仍能在如CHCl3或THF溶液等较少极性的环境中产生单态氧,而在水中单态氧的生成几乎完全被抑制。