Lionetti Davide, Day Victor W, Blakemore James D
Department of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, Kansas 66045, USA.
Dalton Trans. 2017 Sep 12;46(35):11779-11789. doi: 10.1039/c7dt02577g.
A new tripodal ligand featuring three appended pyrene moieties has been prepared for studies of noncovalent binding of lanthanide metal complexes to graphitic carbon surfaces. The ligand tightly binds lanthanide(iii) ions by encapsulation within a heptadentate coordination environment; the cerium, neodymium, samarium, and europium complexes (all with formal metal oxidation state of +3) have been synthesized and characterized. These compounds are readily immobilized on graphitic electrodes-this is driven by the presence of the pyrene moieties, as complexes of an analogous ligand without pyrene groups are not stably adherent to the surface. X-ray photoelectron spectra confirm the molecular identity of the pyrene-appended metal complexes upon immobilization, with unique signals appearing for the metal centers as well as all for all symmetry-related nitrogen atoms on the ligand. Consistent with these surface characterization data and studies of a soluble model compound, the surface-immobilized cerium(iii) complex is reversibly oxidized to cerium(iv) near -0.34 V vs. Fc. Based on electrochemical data, this complex is stable for minutes to hours on the surface.
已制备出一种带有三个附加芘基团的新型三脚架配体，用于研究镧系金属配合物与石墨碳表面的非共价结合。该配体通过在七齿配位环境中包封来紧密结合镧系（III）离子；已合成并表征了铈、钕、钐和铕配合物（所有配合物中金属的形式氧化态均为 +3）。这些化合物很容易固定在石墨电极上——这是由芘基团的存在驱动的，因为没有芘基团的类似配体的配合物不能稳定地附着在表面。X射线光电子能谱证实了固定后芘附加金属配合物的分子结构，金属中心以及配体上所有对称相关氮原子都出现了独特的信号。与这些表面表征数据以及对可溶性模型化合物的研究一致，表面固定的铈（III）配合物在相对于Fc约 -0.34 V处可逆氧化为铈（IV）。基于电化学数据，该配合物在表面可稳定存在数分钟至数小时。
