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.
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
S
S
Coussan
Y
Y
Ferro
A
A
Trivella
M
M
Rajzmann
P
P
Roubin
R
R
Wieczorek
C
C
Manca
P
P
Piecuch
K
K
Kowalski
M
M
Włoch
S A
SA
Kucharski
M
M
Musiał
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