1998 Fiscal Year Final Research Report Summary
Development and application of new NMR technique
| Project/Area Number |
09660110
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bioproduction chemistry/Bioorganic chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
FURIHATA Kazuo The University of Tokyo, Graduate School of Agricultural and Life Sciences, Assistant Professor, 大学院・農学生命科学研究科, 助手 (20219091)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIMURA Eturou The University of Tokyo, Graduate School of Agricultural and Life Sciences, Asso, 大学院・農学生命科学研究科, 助教授 (10130303)
OOKUBO Akira The University of Tokyo, Graduate School of Agricultural and Life Sciences, Asso, 大学院・農学生命科学研究科, 助教授 (20111479)
YAMAZAKI Sunao The University of Tokyo, Graduate School of Agricultural and Life Sciences, Prof, 大学院・農学生命科学研究科, 教授 (00011982)
SETO Haruo The University of Tokyo, Institute of Molecular and Cellular Biosciences, Profes, 分子細胞生物学研究所, 教授 (10013335)
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| Project Period (FY) |
1997 – 1998
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| Keywords | HMBC / Constant-time-HMBC (CT-HMBC) |
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| Research Abstract |
We present a new version of the HMBC technique named constant HMBC (CT-1-HMBC) which enables to improve the separation of carbon signals in the F dimension.
One of the problems of HMBC is that J-modulation due to ^1H-^1H coupling causes line broadening of the ^<13>C-signals in the Fl dimension through couplings of the ^<13>C-signals to their relevant protons during t period. This undesirable effect together with poor separation of ^<13>C-signals may sometimes result in the difficulty for analysis of cross peaks. In order to overcome this problem, we have developed a new technique, constant HMBC (CT-HMBC).
We propose two types of the CT-HMBC experiments, CT-HMBC-1 and CT-HMBC-2. The purpose of employing the constant time method is to keep the effect of the homonuclear 1H-1H J modulation constant during the 2D evolution time (t _1). The CT-HMBC-1 is an analog of the conventional HMBC slightly modified by introduction of the constant time period. Due to this modification, the effect of ^1H-^1H J-modulation remains unchanged during the constant time period.
In the of CT-HMBC-2 pulse sequence, both the effects of ^1H-^1H and ^<13>C-^1H J modulation are fixed. In both methods, the appropriate constant time period (*_3) has to be set by estimation to get satisfactory results. Constant period (*_3) depends on the digital resolution of the t1 dimension. Longer time duration (*_3), will cause the decrease in the sensitivity due to T_<2->.
On the other hand, CT-HMBC-1 spectra can be obtained with good sensitivity comparable to those taken by conventional HMBC experiments. Therefore, the CT-HMBC-1 experiment is highly recommended for structural studies of complicated organic compounds.
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