title: Reversible intramolecular triplet-triplet energy transfer in benzophenone-N-methylphthalimide dyad.
abstract: In the present paper, we synthesized a series of benzophenone (BP)-N-methylphthalimide (MePI) dyads (Cn, n = 3, 6, and 9, where n denotes the number of methylene in the linker) and investigated the photochemical properties and intramolecular triplet-triplet energy transfer from BP(T1) to MePI. Formation of two different intramolecular complexes was found, that is, a ground-state complex and a singlet exciplex. The formation of the triplet-equilibrium between MeBP and MePI was observed. The triplet-equilibrium constant (1.0 and 1.1 for C6 and C9, respectively) and forward ((3.8 +/- 1.3) x 107 and (3.9 +/- 1.2) x 107 s-1 for C6 and C9, respectively) and back ((3.8 +/- 1.3) x 107 and (3.6 +/- 1.2) x 107 s-1 for C6 and C9, respectively) energy transfer rates were estimated from the result of transient absorption measurements. From the van't Hoff plots, enthalpy and entropy change for the equilibrium formation were estimated.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Sung Sik
authors.initials: SS
authors.lastname: Kim
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D001577:Benzophenones / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D004735:Energy Transfer; D007700:Kinetics; D007834:Lasers; D015394:Molecular Structure; D010777:Photochemistry; D010782:Photolysis; D010797:Phthalimides / Q000138:chemical synthesis / Q000737:chemistry* / Q000528:radiation effects; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013997:Time Factors
chemical_list: D001577:Benzophenones; D010797:Phthalimides; C527964:benzophenone-N-methylphthalimide; C047723:benzophenone