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On the Low‐Lying Excited States of sym ‐Triazine‐Based Herbicides
Author(s) -
Oliva Josep M.,
Azenha M. Emilia D. G.,
Burrows Hugh D.,
Coimbra Rita,
Seixas de Melo J. Serxio,
Canle L. Moisés,
Fernández M. Isabel,
Santaballa J. Arturo,
SerranoAndrés Luis
Publication year - 2005
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200400349
Subject(s) - excited state , phosphorescence , chemistry , triazine , luminescence , isopropyl , fluorescence , photochemistry , radiative transfer , atomic physics , physics , optics , organic chemistry
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.