Photostabilization of the herbicide norflurazon by using organoclays.
Photostable formulations of the herbicide norflurazon [4-chloro-5-(methylamino)-2-(alpha,alpha, alpha-trifluoro-m-tolyl)pyridazin-3-(2H)-one] were achieved by adsorbing it on pillared clay or on montmorillonite preadsorbed with the organic cation thioflavin T (TFT). Diffuse reflectance Fourier transform infrared spectra showed the existence of strong interactions between the aromatic moieties of preadsorbed TFT and the herbicide, particularly after irradiation. The photostabilization of norflurazon obtained with TFT-clay was mainly due to energy transfer from the herbicide to the organic cation via pi-pi interactions. An additional mechanism is the lower production of radicals from the clay when the clay mineral surface is covered with the organic cation. These radicals are responsible for the enhanced photodegradation observed when norflurazon was irradiated in the presence of untreated montmorillonite.
Undabeytia
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T
Seagram Center for Soil and Water Sciences, Department of Agricultural Botany, Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
Nir
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S
Tel-Or
E
E
Rubin
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B
D000538:Aluminum Silicates / Q000737:chemistry* / Q000528:radiation effects; D001546:Bentonite / Q000737:chemistry; D000077215:Clay; D006540:Herbicides / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D010777:Photochemistry; D011724:Pyridazines / Q000737:chemistry* / Q000528:radiation effects; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared
D000538:Aluminum Silicates; D006540:Herbicides; D011724:Pyridazines; D001546:Bentonite; C008677:norflurazone; D000077215:Clay