Photochemistry of acetylacetone isolated in parahydrogen matrices upon 266 nm irradiation.
نویسندگان
چکیده
The photochemistry of the chelated enol form of acetylacetone (AcAc) was investigated by UV excitation of the S(2) state at 266 nm in parahydrogen matrices, complemented by experiments in neon and normal hydrogen matrices. Infrared (IR) spectroscopy, combined with theoretical calculations, was used to identify the photoproducts. Isomerization towards various non-chelated forms (no intramolecular H-bond) of AcAc is the dominant channel whereas fragmentation is very minor. The isomerization kinetics is monitored by IR spectroscopy. Among the seven non-chelated conformers of AcAc, only three are formed in parahydrogen matrices, whereas four are observed in normal hydrogen matrices. This difference suggests that an active tunnelling process between conformers occurs in parahydrogen but is quenched in normal hydrogen where guest-host interactions are stronger. Fragmentation and isomerization of excited AcAc are discussed in the light of these new data. The role of the intermediate triplet state in the S(2)→ S(0) relaxation is confirmed, as the importance of phonons in the condensed phase.
منابع مشابه
Hydrogen atom transfer reactions in thiophenol: photogeneration of two new thione isomers.
Photoisomerization reactions of monomeric thiophenol have been investigated for the compound isolated in low-temperature argon matrices. The initial thiophenol population consists exclusively of the thermodynamically most stable thiol form. Phototransformations were induced by irradiation of the matrices with narrowband tunable UV light. Irradiation at λ > 290 nm did not induce any changes in i...
متن کاملConformers, infrared spectrum and UV-induced photochemistry of matrix-isolated furfuryl alcohol.
The infrared spectra of furfuryl alcohol (2-furanmethanol, FFA) were investigated for FFA monomers isolated in low-temperature argon matrices. The structural interpretation of the obtained experimental spectra was assisted by analysis of the molecule's conformational landscape. According to the DFT(B3LYP)/6-311++G(d,p) calculations, five different minimum energy structures were found on the pot...
متن کاملUV-Induced unimolecular photochemistry of diketene isolated in cryogenic inert matrices.
Diketene (C(4)H(4)O(2)) monomers were isolated in cryogenic Ar (15 K) and Xe (30 K) matrices. The infrared (IR) spectra of the freshly deposited matrices show that diketene monomers exclusively adopt the 4-methylene-oxetan-2-one form. In situ photochemical transformations of diketene were induced by tunable UV laser light. Diketene was found to be photostable when exposed to near-UV irradiation...
متن کاملPhotodissociation dynamics of acetylacetone: The OH product state distribution
Acetylacetone in the supersonic jet, which exists predominantly as an enolic form, is found to give rise to the OH fragment after the p – p* transition induced by the UV absorption. The nascent OH product state distributions are determined using a laser-induced fluorescence technique at the excitation wavelengths of 291 and 266 nm. The OH fragment is vibrationally cold, and its rotational state...
متن کاملConformational Space and Photochemistry of r-Terpinene
R-Terpinene is a natural product that is isolated from a variety of plant sources and is used in the pharmaceutical and perfume industries. In the atmosphere, under the influence of sunlight, R-terpinene undergoes a series of photochemical transformations and contributes to the formation of the secondary organic aerosols. In the present work, R-terpinene has been isolated in low-temperature xen...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical chemistry chemical physics : PCCP
دوره 14 10 شماره
صفحات -
تاریخ انتشار 2012