Supra-herbicide based on sunlight-opened macrocycle gate with reduced toxicity.

Scheme 1. Scheme of NP5-PQ supra-herbicide fabrication, light-controlled release properties (a) and recovery of herbicidal activity (b). [Display omitted] • The supra-herbicide could reduce the toxicity of PQ via molecular shielding effect. • Under the exposure of sunlight, PQ released and the herbicidal activity was recovered owing to the fracture of NP5 macrocycles. • This is first example of supra-herbicide based on sunlight-opened macrocycle gate, which could reduce the toxicity of PQ without losing herbicidal activity. Supramolecular herbicide was fabricated through the host–guest complexation of prism[5]arene (NP5) and paraquat (PQ). For the supra-herbicide, the toxicity of PQ could be reduced by molecular shielding effect. Under exposure to sunlight, NP5 gate was opened to release PQ and the herbicidal activity was recovered. [ABSTRACT FROM AUTHOR]