Crystal structure and biological activity studies of two different types of herbicide safeners

Two heterocyclic compounds, imidazolidine-1,3-diylbis((5-methyl-3-phenylisoxazol-4-yl)methanone) (I) and (5-methylisoxazol-3-yl)(1-oxa-4-azaspiro[4.5]decan-4-yl)methanone (II), were characterized by X-rays. Compound I was crystallized in monoclinic system, space group Cc, a= 9.81000(12) Å, b= 15.21199(16) Å, c= 14.25369(17) Å, β= 90.3862 (12)degree, Z= 4, V= 2127.02(4) Å3, F(000) = 928.0, Dc= 1.382 Mg/m3, crystal size: 0.150 x 0.130 x 0.120 mm. Compound II was crystallized in the monoclinic system, space group P21/n, a = 5.6113(5) Å, b = 11.2280(10) Å, c = 20.675(2) Å, β = 95.543(10)degree, Z = 4, V = 1296.5(2) Å3, F(000) = 536.0, Dc = 1.282 Mg/m3, crystal size: 0.130 x 0.120 X 0.110 mm. Bioactivity assays showed that both compounds have good safety activity against nicosulfuron injury to corn, comparable to the commercial safener isoxadifen-ethyl. The molecular docking model indicated that two types of herbicide safeners competed with nicosulfuron for the acetolactate synthase active site and that this is the protective mechanism of safeners.. KEYWORDS :1,3-Disubstituted imidazolidine, Aryl-substituted formyloxazolidines, Single-crystal structure, Herbicide safener activity.