2001 Fiscal Year Final Research Report Summary
Studies on meta effect appears in dioxetane chemiluminescence and ester photolysis
| Project/Area Number |
11440212
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
物質変換
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| Research Institution | University of Tsukuba |
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Principal Investigator |
FUJIMORI Ken University of Tsukuba, Chemistry, Associate Professor, 化学系, 助教授 (90015983)
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| Co-Investigator(Kenkyū-buntansha) |
村田 重夫 物質工学工業技術研究所, COE特別研究室・反応機構斑, 主任研究官
MATSUMOTO Masakatsu Kanagawa University, Chemistry, Professor, 理学部, 教授 (10260986)
MORIHASHI Kenji University of Tsukuba, Chemistry, Associate Professor, 化学系, 助教授 (90182261)
岩井 伸一郎 物質工学工業技術研究所, COE特別研究室・反応機構斑, 研究官
加藤 隆二 物質工学工業技術研究所, COE特別研究室・反応機構斑, 主任研究官
MURATA S. NIMIC, COE Laboratory, Senior Researcher
IWAI S. NIMIC, COE Laboratory, Researcher
KATOH R. NIMIC, COE Laboratory, Senior Researcher
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| Project Period (FY) |
1999 – 2000
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| Keywords | meta effect / photosolvolvsis / photolysis / homolysis / heterolysis / dioxetane / excited triplet state / chemiluminescence |
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| Research Abstract |
Photolysis of m- and p-methoxybenzyl acetates (I_m and I_p) in methanol has been investigated and found the followings : (a) Photochemical C-O bond fission of I_m occurs from the excited singlet state, while that of I_p occurs from the triplet state ; (b) Φ_r apparently lower for I_m photolysis than for I_p is due to internal return of intimate pairs, I.e., the C-O bond fission quantum yield is 1 for I_m while 0.8 for I_p. c C-O bond cleavage of the excited singlet state of I_m occurs so readily that photolysis produce a singlet radical pair and ion pair origin products accompanied by extremely low fluorescence. Because C-O bonding splits slowly in the excited singlet state of I_p, intersystem crossing becomes the major pathway for excited singlet state reactions, resulting in a moderate yield of fluorescence and a high yield of the triplet state, and eventually yielding free radical origin products. The major factor determining I photolysis products is the relative rate of C-O bond cleavage in the excited singlet state versus intersystem crossing. The reason why C-O bond cleavage of excited singlet state of I_m is very fast while that of I_p is slow has been studied by quantum mechanical theory.
When 3-methoxy-3-(w- and p-methoxyphenyl)-4,4-adamantiliden-l ,2-dioxetane (II_m, II_p) is photolyzed in a glassy matrix at 77K, adamantanone adjacent to S_l state of methyl methoxybenzoate plays as an external machine to alter electron spin multiplicity of the ester from S_l to T_l, by the energy return, mechanism, p-orbital overlapping between the ester and adamantanone is necessary to work the energy return mechanism between methyl m-methoxybenzoate and adamantanone. Intimate pair ofmethyl p-ethoxybenzoate and adamantanone generated through photolysis of II_p in glassy matrix at 77K forms exciplex. Energy transfer business that occurs immediately after the II_p fragmentation between two carbonyl fragments determines fate of ehemiluminescenee.
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Research Products
(2 results)
