On the low-lying excited states of sym-triazine-based herbicides.
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-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I 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.
Oliva
Josep M
JM
Instituto de Química Física Rocasolano, Consejo Superior de Investigaciones Cientfficas Serrano 119, 28006 Madrid Spain.
Azenha
M Emilia D G
ME
Burrows
Hugh D
HD
Coimbra
Rita
R
Seixas de Melo
J Serxio
JS
Moisés Canle
L
L
Fernández
M Isabel
MI
Santaballa
J Arturo
JA
Serrano-Andrés
Luis
L
D000042:Absorption; D001280:Atrazine / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D006540:Herbicides / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000737:chemistry; D008956:Models, Chemical; D008962:Models, Theoretical; D015394:Molecular Structure; D009991:Oscillometry; D011312:Pressure; D012984:Software; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013696:Temperature; D014227:Triazines / Q000737:chemistry
D006540:Herbicides; D007202:Indicators and Reagents; D014227:Triazines; D001280:Atrazine