文摘
Construction of GdIII photosensitizers is important for designing theranostic agents owing to the unique properties arising from seven unpaired f electrons of the Gd3+ ion. Combining these with the advantages of porpholactones with tunable NIR absorption, we herein report the synthesis of GdIII complexes Gd-1–4 (1, porphyrin; 2, porpholactone; 3 and 4, cis- and trans-porphodilactone, respectively) and investigated their function as singlet oxygen (1O2) photosensitizers. These Gd complexes displayed 1O2 quantum yields (ΦΔs) from 0.64–0.99 with the order Gd-1<Gd-2<Gd-3<Gd-4. The gradually enhanced 1O2 sensitization after β-oxazolone moiety replacement was ascribed to the narrowing of the energy gap (ΔE) between the lowest triplet states (T1) of the ligand and the energy level of the 1Δg→3Σg transition of 1O2. In particular, Gd-4 is capable of excitation in the visible to NIR region (400–700 nm) with a quantum yield near unity. These Gd complexes were first demonstrated as efficient photosensitizers in photocatalysis such as oxidative C−H bond functionalization of secondary or tertiary amines, and the oxygenation of the natural product cholesterol. Finally, after glycosylation, these water-soluble Gd complexes showed potential applications in photodynamic therapy (PDT) in HeLa cells. This work revealed that GdIII complexes of “bioinspired” β-modified porpholactones are efficient NIR photosensitizers and form a chemical basis to construct appealing photocatalysts and theranostic agents based on lanthanides.