Issue 68, 2016

Phototransformation of tetrazoline oxime ethers – part 2: theoretical investigation

Abstract

The competitive photoisomerization and photodegradation reactions of a tetrazoline oxime ether showing important fungicidal activity are investigated by Time Dependent-Density Functional Theory (TD-DFT) and Complete Active Space Self-Consistent Field (CASSCF) calculations of ground state and excited state (singlet, S and triplet, T) potential energy surfaces. Two key experimental results reported previously are explained in this study: (1) why only E isomers undergo N–O bond scission and photodegradation and (2) what is the mechanism for deactivation of the Z isomers. In addition, the reactive pathway that involves intersystem crossing is shown to be competitive with reactions in the singlet state. Our results demonstrate that the photoreactivity (photodegradation or photoisomerization) of the eight conformers studied here is clearly related to the differences between the respective electronic configurations of the lowest singlet excited state. It is shown that the addition of a bulky substituent on the pyridyl group prevents E isomers from being photodegraded.

Graphical abstract: Phototransformation of tetrazoline oxime ethers – part 2: theoretical investigation

Supplementary files

Article information

Article type
Paper
Submitted
24 Mar 2016
Accepted
27 Jun 2016
First published
28 Jun 2016

RSC Adv., 2016,6, 63965-63972

Phototransformation of tetrazoline oxime ethers – part 2: theoretical investigation

M. Fréneau, N. Hoffmann, J. Vors, P. Genix, C. Richard and P. de Sainte Claire, RSC Adv., 2016, 6, 63965 DOI: 10.1039/C6RA07712A

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