Molecular Spectroscopic Study of Metallofullerenes

电子自旋共振(ESR)谱是表征面内金属富勒烯的有力手段。在我的演讲中介绍了几个金属富勒烯的ESR测量实例。除了传统的CW-ESR技术外，脉冲ESR技术进一步发展了对金属富勒烯性质的研究，大量地获得了各种稀土金属的富勒烯[1-3]。其中Gd原子的电子结构被描述为4f^75d^16s^2，预期为基态高自旋态。我们用X和W波段的ESR波谱仪研究了Gd@C&lt；82&gt；。X-波段ESR谱表现出与具有大精细结构的高自旋体系相对应的复杂模式。由于存在较大的零场分裂参数D和E，给出了非对称的光谱特征，阻碍了我们进行简单的光谱模拟。为了简化Gd@C&lt；82&Gt；的光谱，进行了W波段的ESR测量。我向大家介绍…此外，W波段的ESR测量结果和对Gd@C_&lt；82&Gt；的电子结构的讨论表明，顺磁性金属富勒烯是构成分子磁体的良好材料。用更大的π共轭分子包覆金属富勒烯是非常有兴趣的，这可能导致超分子磁体以3D方式延伸。Tashiro et al.合成了金属卟啉环状二聚体[4]，并报道了环状二聚体锌与C_(60)包合物在苯溶液中的大结合常数为6.7×10~(-5)M~(-1)。用脉冲ESR方法研究了金属卟啉与金属富勒烯形成的环状二聚体包合物的电子自旋态。通过脉冲电子自旋共振章动测量，得到了铜-卟啉与La@C&lt；82&gt；的环状二聚体的S=3/2耦合自旋态的直接实验证据。包合物的自旋状态预计会有很大的变化，因为金属在卟啉和富勒烯上的结合。较少

Electron spin resonance (ESR) spectroscopy has been a powerful technique for the characterization endohedral metallofullerenes. Several examples of the ESR measurement for metallofullerenes are introduced in my talk. Besides a conventional cw-ESR technique, a pulsed-ESR technique developed the further investigation for the properties of metallofullerenes.Various metallofullerenes of lanthanide metals were abundantly obtained [1-3]. Among them the electronic structure of Gd atom is described as 4f^75d^16s^2, and the ground high spin state is expected. We examined Gd@C_<82> by means of X- and W-band ESR spectrometers. The spectrum of X-band ESR exhibited a complex pattern corresponding to that for the high-spin system with large fine structure. The un-symmetric spectral feature was given because of the large zero-field splitting parameters D and E, and prevented us from an easy spectral simulation. The W-band ESR measurement was performed to simplify the spectrum of Gd@C_<82>. I present … More the result of the W-band ESR measurement and the discussion of the electronic structure of Gd@C_<82>.A paramagnetic metallofullerene is a nice building block for a molecular magnet. Wrapping of a metallofullerene with larger π-conjugated molecular envelopes is of great interest, which may lead to an extension of the super-molecular magnet in a 3D-fashion. Tashiro et al. have synthesized a cyclic dimmer of metalloporphyrin [4], and reported the big association constant of 6.7 x 10^5 M^<-1> for the inclusion complex of a cyclic dimmer of zinc porphyrin with C_<60> in benzene solution. The electron spin state of an inclusion complex of a cyclic dimmer of metalloporphyrin with metallofullerene was investigated by means of pulsed-ESR measurement. The direct experimental evidence of the coupled spin state of S=3/2 was obtained for the cyclic dimmer of copper-porphyrin with La@C_<82> by the nutation measurement of pulsed-ESR. A big variety would be expected for the spin state of the inclusion complex in terms of the combination of metals on a porphyrin and a fullerene. Less