Laser photolysis studies of endothermic triplet energy transfer in solution
| Project/Area Number |
15550004
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Physical chemistry
|
|---|
| Research Institution | Gunma University |
|---|
Principal Investigator |
YAMAJI Minoru Gunma University, Department of Chemistry, Associate Professor, 工学部, 助教授 (20220361)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOBITA Seiji Gunma University, Department of Chemistry, Professor, 工学部, 教授 (30164007)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Project Status |
Completed (Fiscal Year 2004)
|
| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2004: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
|
|---|
| Keywords | triplet energy transfer / Laser flash photolysis / bond dissociation / endothermic energy transfer / reaction dynamics / 速度定数 / 反応経路 / レーザー閃光分解 / ベンゾフェノン / 解離反応 / 活性化エネルギー / ナフチルフエニルケトン / 炭素-イオウ結合解離 |
|---|
| Research Abstract |
A bimolecular rate constant (κ_q) and an efficiency (α_<TET>) of an endoergonic triplet energy transfer from triplet α-naphthyl phenyl ketone(NPK) to α-naphthylmethyl phenyl sulfide(NMPS) in solution, where the energy difference (ΔE_T) is 1.7 kcal mol^<-1>, have been determined by means of nanosecond laser flash photolysis. Base on the Arrhenius plots of the κ_q value for the NPK-NMPS system, an activation energy (ΔE_a) for the endoergonic triplet energy transfer is found to be 2.6 kcal mol^<-1>, which is larger than the endothermic energy gap (ΔE_T=1.7 kcal mol^<-1>). The endoergonic triplet energy transfer in solution is demonstrated to proceed with the aid of thermal activation for the first time.
The triplet-sensitized photoreactions of the title biplanophane system 6, the photoisomer of a 2.11-diaza[3,3](9,10)anthracenoparacyclophane derivative 5, were investigated by stationary and laser flash photolyses using xanthone(XT) and benzophenone(BP) as triplet sensitizers. Upon XT-sensi
… More
tized irradiation of the photoisomer 6, a cyclophane 5 and a novel polycyclic product 7 were obtained via an adiabatic cycloreversion and a formal [2πa+2πa+ 2σs] rearrangement. The maximum quantum yield for formation of the cyclophane 5 (0.69) and the upper-limit efficiency for formation of the polycycle 7 (0.31) were determined by laser photolysis techniques. For BP-sensitized photolysis of the photoisomer 6, an oxetane 8 was formed via a Paterno-Buchi reaction in addition to cyclophane 5 and polycycle 7. Quenching rate constant (κ_q) of the triplet sensitizers by photoisomer 6 was smaller by one order of magnitude for BP (3.4x 10^8 dm^3 mol^<-1> s^<-1>) than for XT (5.0x10^9 dm^3 mol^<-1> s^<-1>) and the triplet energy level of photoisomer 6 was estimated as 71 kcal mol^<-1> based on the relationship between κ_q and triplet donor-acceptor energy gap. The photochemical and the photophysical processes involved in the sensitized photolyses are summarized in an energetic reaction diagram and discussed in detail. Less
|
Report
(3 results)
Research Products
(16 results)
