Synthesis and antifungal activity of slow-release pyridinylcarbonyl chitooligosaccharide copper complexes.

ABSTRACT

Copper fungicides are fungicides have a wide application, but their toxicity to plant growth and the damage they cause to the environment cannot be ignored. As such, the novel, low toxicity biogenic copper fungicide has strong industrial application prospects. Herein, pyridinylcarbonyl chitooligosaccharide ligands (pCOSx) and their copper complexes (pCOSx-Cu) were synthesized. The results showed that a p-π-π conjugated system was formed in pCOSx, resulting in the formation of a slowly dissociated coordination bond between the nitrogen atom of pyridyl and Cu2+ in pCOSx-Cu. The cumulative release rate of Cu2+ is positively correlated with the electron donating ability of pyridyl. Compared with the commercial copper fungicide thiodiazole­copper, pCOSx-Cu exhibited better antifungal activity, lower phytotoxicity and better biocompatibility. This work demonstrated that it was feasible to construct a conjugated system in a chitooligosaccharide copper complex to improve slow-release performance, which laid a foundation for the in-depth study of green copper fungicides. CHEMICAL COMPOUNDS Chitooligosaccharide (PubChem CID 3086191); Nicotinoyl chloride hydrochloride (PubChem CID 88438); Isonicotinoyl chloride hydrochloride (PubChem CID 12262826); 2-chloronicotinoyl chloride (PubChem CID 2774541); Trimethylchlorosilane (PubChem CID 6397); Tetrabutylammonium fluoride (PubChem CID 2724141); Copper (II) acetate monohydrate (PubChem CID 165397).