Abstract: La(Ⅲ)-chlorophyll-a was synthesized in mixed solution of methanol and acetic acid. The room temperature UV-Vis and variable temperature MCD spectra of La(Ⅲ)-chlorophyll-a, chlorophyll-a and pheophytin-a were studied in tetrahydro-2-methylfuran solvent. The UV-Vis and MCD spectra of La(Ⅲ)-chlorophy-a are very similar to those of chlorophyll-a, but different from those of pheophytin-a. This shows that porphyrin ring of pheophytin-a is coordinated to La(Ⅲ) ion, and gives new complex. All variable temperature MCD spectra show the present of Faraday C term, which may be contributed by the cation radicals. This need to be further verified by EPR spectra. In addition, La(Ⅲ)-chlorophyll-a may have similar monoporphyrin structure with chlorophyll-a from their similar MCD spectra.

Key words: Chlorophyll, La(Ⅲ)-chlorophyll, MCD spectra

摘要： 在甲醇和醋酸体系中合成得到翠绿色的叶绿素镧配合物，研究了它和叶绿素a、脱镁叶绿素a的紫外可见光谱，并首次研究了它们的磁园二色性谱(MCD谱)。叶绿素镧的UV-Vis谱和MCD谱与叶绿素a的相似，但是与脱镁叶绿素a有明显的区别，从而证明了镧离子已配位到叶绿素的卟啉环上，并形成了金属叶绿素镧的配合物。三者的变温MCD谱均含有C项的贡献，对于C项的来源，初步推测为体系中产生的自由基，这有待于EPR谱和更宽温度范围的MCD研究来确认。此外，由MCD谱推断叶绿素镧与叶绿素a具有相似的单层结构。

关键词: 叶绿素a, 叶绿素镧, MCD谱