Tetra-2,3-pyrazinoporphyrazines with Externally Appended Thienyl Rings: Synthesis, UV鈥揤isible Spectra, Electrochemical Behavior, and Photoactivity for the Generation of Singlet Oxygen

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• 作者：Giorgia De Mori ; Zhen Fu ; Elisa Viola ; Xiaohui Cai ; Claudio Ercolani ; Maria Pia Donzello ; Karl M. Kadish
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：September 5, 2011
• 年：2011
• 卷：50
• 期：17
• 页码：8225-8237
• 全文大小：1137K
• 年卷期：v.50,no.17(September 5, 2011)
• ISSN：1520-510X

文摘

A series of pyrazinoporphyrazine macrocycles carrying externally appended 2-thienyl rings, represented as [Th₈TPyzPzM], where Th₈TPyzPz = tetrakis-2,3-[5,6-di(2-thienyl)pyrazino]porphyrazinato anion and M = Mg^II(H₂O), Zn^II, Co^II, Cu^II, or 2H¹, were prepared and isolated as solid air-stable hydrated species. All of the compounds, completely insoluble in water, were characterized by their UV鈥搗isible spectra and electrochemical behavior in solutions of dimethylformamide (DMF), dimethyl sulfoxide, and pyridine. Molecular aggregation occurs at concentrations of ca. 10^鈥? M, but monomers are formed in more dilute solutions of 10^鈥? M or less. The examined octathienyl compounds [Th₈TPyzPzM] behave as electron-deficient macrocycles, and UV鈥搗isible spectral measurements provide useful information about how the peripheral thienyl rings influence the electronic distribution over the entire macrocyclic framework. Cyclic voltammetric and spectroelectrochemical data confirm the easier reducibility of the compounds as compared to the related phthalocyanine analogues, and the overall redox behavior and thermodynamic potentials for the four stepwise one-electron reductions of the compounds are similar to those of the earlier examined octapyridinated analogues [Py₈TPyzPzM]. Quantum yields (桅_螖) for the generation of singlet oxygen, ¹O₂, the cytotoxic agent active in photodynamic therapy (PDT), and fluorescence quantum yields (桅_F) were measured for the Zn^II and Mg^II complexes, [Th₈TPyzPzZn] and [Th₈TPyzPzMg(H₂O)], and the data were compared to those of corresponding octapyridino macrocycles [Py₈TPyzPzZn] and [Py₈TPyzPzMg(H₂O)] and their related octacations [(2-Mepy)₈TPyzPzZn]⁸⁺ and [(2-Mepy)₈TPyzPzMg(H₂O)]⁸⁺. These measurements were carried out in DMF and in DMF preacidified with HCl (ca. 10^鈥? M). All of the examined Zn^II compounds behave as excellent photosensitizers (桅_螖 = 0.4鈥?.6) both in DMF and DMF/HCl solutions, whereas noticeable fluorescence activity (桅_F = 0.36鈥?.43) in DMF/HCl solutions is shown by the Mg^II derivatives; these data might provide perspectives for applications in PDT (Zn^II) and imaging response and diagnosis (Mg^II).