Keggin polyoxometalates based hybrid compounds containing helix/nanocages for colorimetric biosensing

Highlights: • Two new Keggin polyoxometalates (POMs) based hybrid compounds containing helix/nanocages are reported. • Compounds 1 and 2 both exhibit higher peroxidase-like activities and broader applications range than other POMs involved peroxidase-like mimics. • Compounds 1 and 2 both exhibit faster respond time and lower detection limit than other POMs involved peroxidase-like mimics. - Abstract: Two Keggin polyoxometalate (POMs) based hybrid compounds containing helix/nanocages as peroxidase-like mimics have been synthesized and structurally characterized. Single crystal X-ray diffraction analysis reveals that compound 1 exhibits a POM-pillared framework with open nanotube channels (ca. 5.6 × 5.8 Ų), in which SiW₁₂ polyanions are sandwiched between the adjacent Cu-fkz sheets with meso-helix. And an unprecedented twisted octahedral hexamer nanocage (ca. 10 × 10 Ų) is observed in compound 2. Compared with the other POMs involved peroxidase-like mimics, both compounds 1 and 2 exhibit higher peroxidase-like catalytic activities, broader applications range, faster respond time and lower detection limit, which maybe attribute to the maximized synergistic effects of SiW₁₂ clusters, fkz molecules, metal ions and the distinct structure. Based on the facts, compounds 1 and 2 as enzyme mimics might expand their application around physiological pH conditions, and can be used as one kind of effective probe to detect H₂O₂ in live organism.