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Experimental and Theoretical Studies on Photodegradation of Fungicide Diniconazole
Toshiyuki KATAGI
J. Pestic. Sci.
27, 111-117 (2002)
The fungicide diniconazole [(E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol] underwent (E)/(Z) isomerization and subsequent cyclization of its (Z)-isomer to form an isoquinoline derivative on exposure to UV light ([lambda]D250 nm) in methanol. The molecular geometry of the (Z)-isomer estimated from the semi-empirical AM1 molecular orbital calculations based on measurements of nuclear spin-lattice relaxation times was successfully utilized to simulate the electronic transitions of the fluorescent difluorinated derivative of the (Z)-isomer by CNDO/S calculations taking configuration interactions into consideration. The photolysis index for one-electron transition ([DELTA]Mij) strongly suggested that photo-induced cyclization proceeds via an excited singlet state.
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