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On the Low-Lying Excited States of sym-Triazine-Based Herbicides

✍ Scribed by Josep M. Oliva; M. Emilia D. G. Azenha; Hugh D. Burrows; Rita Coimbra; J. Serxio Seixas de Melo; Moisés Canle L.; M. Isabel Fernández; J. Arturo Santaballa; Luis Serrano-Andrés

Publisher
John Wiley and Sons
Year
2005
Tongue
English
Weight
165 KB
Volume
6
Category
Article
ISSN
1439-4235

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✦ Synopsis

Abstract

We report a joint computational and luminescence study on the low‐lying excited states of sym__‐triazines, namely, 1,3,5‐triazine (1) and the ubiquitous herbicides atrazine [6‐chloro‐N^2^‐ethyl‐N^4^‐isopropyl‐1,3,5‐triazine‐2,4‐diamine (2)] and ametryn [6‐methylthio‐N^2^‐ethyl‐N^4^‐isopropyl‐1,3,5‐triazine‐2,4‐diamine (3)]. Geometrical structures, energetics, and transition and state properties of 1 and 2 were computed at the TD‐DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates were determined. The predictions from CASPT2 calculations are in good agreement with the experimental results obtained from the luminescence studies and allow the interpretation of different absorption and emission features.__

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