Experimental and theoretical UV characterizations of acetylacetone and its isomers.
Cryogenic matrix isolation experiments have allowed the measurement of the UV absorption spectra of the high-energy non-chelated isomers of acetylacetone, these isomers being produced by UV irradiation of the stable chelated form. Their identification has been done by coupling selective UV-induced isomerization, infrared spectroscopy, and harmonic vibrational frequency calculations using density functional theory. The relative energies of the chelated and non-chelated forms of acetylacetone in the S0 state have been obtained using density functional theory and coupled-cluster methods. For each isomer of acetylacetone, we have calculated the UV transition energies and dipole oscillator strengths using the excited-state coupled-cluster methods, including EOMCCSD (equation-of-motion coupled-cluster method with singles and doubles) and CR-EOMCCSD(T) (the completely renormalized EOMCC approach with singles, doubles, and non-iterative triples). For dipole-allowed transition energies, there is a very good agreement between experiment and theory. In particular, the CR-EOMCCSD(T) approach explains the blue shift in the electronic spectrum due to the formation of the non-chelated species after the UV irradiation of the chelated form of acetylacetone. Both experiment and CR-EOMCCSD(T) theory identify two among the seven non-chelated forms to be characterized by red-shifted UV transitions relative to the remaining five non-chelated isomers.
Coussan
S
S
Laboratoire Physique des Interactions Ioniques et Moléculaires, UMR 6633, Université de Provence-CNRS, Centre St-Jérôme, 13397 Marseille Cedex 20, France. coussan@up.univ-mrs.fr
Ferro
Y
Y
Trivella
A
A
Rajzmann
M
M
Roubin
P
P
Wieczorek
R
R
Manca
C
C
Piecuch
P
P
Kowalski
K
K
Włoch
M
M
Kucharski
S A
SA
Musiał
M
M
D008956:Models, Chemical; D015394:Molecular Structure; D010422:Pentanones / Q000737:chemistry* / Q000528:radiation effects*; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013237:Stereoisomerism; D014466:Ultraviolet Rays
D010422:Pentanones; C008790:acetylacetone