ASSIGNMENTS IN NATURAL-ABUNDANCE C-13 NUCLEAR MAGNETIC-RESONANCE SPECTRUM OF CHLOROPHYLL A AND A STUDY OF SEGMENTAL MOTION IN NEAT PHYTOL
ASSIGNMENTS IN NATURAL-ABUNDANCE C-13 NUCLEAR MAGNETIC-RESONANCE SPECTRUM OF CHLOROPHYLL A AND A STUDY OF SEGMENTAL MOTION IN NEAT PHYTOL
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DOI：
10.1021/ja00804a003
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发表时间：
1973-01-01
影响因子：
15
通讯作者：
ALLERHAND, A
中科院分区：
文献类型：
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作者：
GOODMAN, RA;OLDFIELD, E;ALLERHAND, A
我们记录了叶绿醇、乙酸植酯和叶绿素 a 的质子解耦自然丰度 13C 光谱（15.18 MHz）。植醇的 20 个碳产生 19 个峰。我们利用 Grant 和 Paul 的化学位移参数，将植醇的 18 个单碳共振中的 16 个分配给特定的碳，与植醇和植醇-植醇混合物的光谱进行比较，以及纯植醇的各个碳的 13C 自旋晶格弛豫时间 (Tí)。甚至一些由植醇分子中心附近结构非常相似的碳引起的相距小于 0.1 ppm 的共振也被专门指定。通过使用单频偏共振质子去耦并与植醇的光谱进行比较，确定了乙酸植醇的 13C 共振。然后使用乙酸植酯作为模型来识别和分配溶解在氯仿-甲醇混合物中的叶绿素a的13C光谱中的所有植基碳共振。纯植醇 (at52) 的 Tí 值产生了有关支化植醇链中片段运动的信息。将观察到的行为与无支链 1-癸醇分子的行为进行比较。虽然纯 1-癸醇的碳的有效旋转相关时间朝着分子的羟基端单调增加，但在植醇的情况下，由于支化和烯键的存在，存在单调行为的局部偏差。
We have recorded the proton-decoupled natural-abundance 13C spectra (at 15.18 MHz) of phytol, phytyl acetate, and chlorophyll a. The 20 carbons of phytol yield 19 peaks. We have assigned 16 out of the 18 single-carbon resonances of phytol to specific carbons with the use of the chemical shift parameters of Grant and Paul, comparisons with the spectrum of pristane and of a phytol-pristane mixture, and 13C spin-lattice relaxation times (Tí) of individual carbons of neat phytol. Even some resonances separated by less than 0.1 ppm arising from structurally very similar carbons near the center of the phytol molecule were specifically assigned. The 13C resonances of phytyl acetate were assigned with the use of single-frequency off-resonance proton decoupling and a com-parison with the spectrum of phytol. Phytyl acetate was then used as a model for identifying and assigning all the phytyl carbon resonances in the 13C spectrum of chlorophyll a dissolved in a chloroform-methanol mixture. The Tí values of neat phytol (at52) yielded information about the segmental motions in the branched phytyl chain. The observed behavior is compared with that of the unbranched 1-decanol molecule. While the effective rota-tional correlation time of the carbons of neat 1-decanol increases monotonically toward the hydroxyl end of the molecule, in the case of phytol there are localized deviations from monotonic behavior, as a result of branching and the presence of an olefinic bond.