Determination of triplet excitation energies of cyclic enones by time-resolved photoacoustic calorimetry. 1990

D I Schuster, and G E Heibel, and R A Caldwell, and W Tang
Department of Chemistry, New York University, NY 10003.

Energies and lifetimes of triplet states of a series of 2-cyclohexenones have been measured in solution under ambient conditions by time-resolved photoacoustic calorimetry (PAC). The PAC triplet lifetimes are in excellent agreement with lifetimes measured by kinetic absorption spectrophotometry (KAS) using nanosecond flash techniques, indicating that the present data indeed pertain to the enone triplets previously studied using KAS. The data demonstrate that, as previously proposed, the pi pi triplet energies in these systems are indeed correlated with triplet lifetimes, and vary sensibly with the anticipated extent of conformational flexibility of the C = C bond. No evidence supporting formation of metastable trans-cyclohexenones was obtained. The data also demonstrate greater precision and, for lifetimes, greater accuracy than has hitherto been claimed for the PAC technique for study of transients with lifetimes in the 25 ns range.

UI MeSH Term Description Entries
D010777 Photochemistry A branch of physical chemistry which studies chemical reactions, isomerization and physical behavior that may occur under the influence of visible and/or ultraviolet light. Photochemistries
D002151 Calorimetry The measurement of the quantity of heat involved in various processes, such as chemical reactions, changes of state, and formations of solutions, or in the determination of the heat capacities of substances. The fundamental unit of measurement is the joule or the calorie (4.184 joules). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D002627 Chemistry, Physical The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes. Physical Chemistry,Chemistries, Physical,Physical Chemistries
D003512 Cyclohexanones Cyclohexane ring substituted by one or more ketones in any position.
D055598 Chemical Phenomena The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes. Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical

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