镧系金属富勒烯和π-扩展四硫富瓦烯的给体-受体轭合物。

Donor-acceptor conjugates of lanthanum endohedral metallofullerene and pi-extended tetrathiafulvalene.

机构信息

Departamento de Química Orgánica I, Facultad de Química, Universidad Complutense, E-28040 Madrid, Spain.

出版信息

J Am Chem Soc. 2010 Jun 16;132(23):8048-55. doi: 10.1021/ja100665q.

PMID:20491484

Abstract

Stable donor-acceptor conjugates (2, 3) involving an endohedral metallofullerene, La(2)@I(h)-C(80), and pi-extended tetrathiafulvalene (exTTF) have been synthesized by highly regioselective 1,3-dipolar cycloadditions of exTTF-containing azomethine ylides to the endofullerene, yielding exclusively [5,6] metallofulleropyrrolidines with C(1) symmetry in high yields (68-77%). The cyclic voltammograms (CVs) of the conjugates reveal the redox active character of the system due to the presence of both donor and acceptor groups, that is, exTTF and La(2)@I(h)-C(80), respectively. Furthermore, the electrochemically reversible character of the endofullerene confirms the presence of the [5,6] adduct. Despite the relatively close proximity between the exTTF and the endohedral metallofullerene (EMF), only a weak electronic interaction was observed in the ground state, as evidenced by absorption spectroscopy and CV measurements of 2 and 3. On the other hand, in the excited state the fast formation of a radical ion-pair state (i.e., 6.0 x 10(10) s(-1)), that is, the reduction of the electron accepting La(2)@C(80) and the oxidation of exTTF, evolves with lifetimes as long as several ns (3.0 x 10(8) s(-1)) in toluene. Transient absorption spectroscopy experiments confirmed these observations.

摘要

稳定的给体-受体轭合物（2、3）涉及金属富勒烯内包物 La(2)@I(h)-C(80)和 π-扩展四硫富瓦烯（exTTF），通过 exTTF 含亚胺叶立德与内包 fullerene 的高区域选择性 1,3-偶极环加成反应合成，产率高达 68-77%（68-77%），生成具有 C(1)对称性的[5,6]金属富勒吡咯烷。共轭物的循环伏安（CV）图由于存在供体和受体基团（即 exTTF 和 La(2)@I(h)-C(80）），显示出该体系的氧化还原活性特征。此外，内包 fullerene 的电化学可逆性特征证实了[5,6]加合物的存在。尽管 exTTF 和内包金属富勒烯（EMF）之间的距离相对较近，但在基态下仅观察到较弱的电子相互作用，这可通过吸收光谱和 2 和 3 的 CV 测量来证明。另一方面，在激发态下，自由基离子对态（即，La(2)@C(80)的还原和 exTTF 的氧化）的快速形成以长达几个纳秒（3.0 x 10(8) s(-1)）的寿命在甲苯中发展。瞬态吸收光谱实验证实了这些观察结果。