Dipartimento di Chimica, Università degli Studi di Roma La Sapienza, p.le Aldo Moro 5, I-00185 Roma, Italy.
Phys Chem Chem Phys. 2011 Mar 14;13(10):4452-62. doi: 10.1039/c0cp01921f. Epub 2011 Jan 24.
Specific and reversible binding of guest molecules from a solution to a surface pre-treated with host molecules is a recent and active field of research. Self-assembled monolayers may result from supramolecular interactions, adding distinct functionalities to the surface. In this frame, the first compared study is given here of the anchoring on the technologically relevant Cu surface of calix[4]arene receptors and calix[6]arene-based rotaxanes and pseudorotaxanes. These molecules, which belong to the most representative classes of compounds in supramolecular chemistry, have been chosen for their synthetic accessibility and versatility, which make them useful building blocks for the synthesis of new advanced supramolecular structures. Covalent functionalisation of calix[4,6]arenes on Cu was reached via a dip-coating procedure, optimizing the various synthetic aspects in order to obtain good coverages and copper passivation. Molecular adhesion has been demonstrated by the presence and relative quantitation of XPS signals from specific elements in the molecules. We have successfully tested the combination of different functionalities by producing a mixed film, prepared by ligand exchange of calix[4]arene with undecanethiol. The availability of the calix[4]arene cavity to reversibly host further species after anchoring on Cu has been demonstrated by a sequence of uptake and release cycles with pyridinium salts. Rotaxane and pseudorotaxane species, composed of a calix[6]arene wheel functionalized with N-phenylurea groups on the upper rim, and a viologen-containing axle, have been anchored on Cu via the SH-termination of the axle. XPS demonstrated the successful self-assembly of fully threaded rotaxanes and pseudorotaxanes from their solutions and the controlled release upon biasing of full rotaxanes and of the pseudorotaxane wheel.
客体分子从溶液中特异性且可逆地结合到经主体分子预处理的表面是一个新兴且活跃的研究领域。自组装单层膜可能源于超分子相互作用，为表面增加独特的功能。在这种情况下，本文首次比较了杯[4]芳烃受体和杯[6]芳烃基轮烷及类轮烷在技术上相关的 Cu 表面上的锚定。这些分子属于超分子化学中最具代表性的化合物类别，由于其合成的可及性和多功能性而被选择，这使它们成为合成新型先进超分子结构的有用构建块。通过浸涂程序实现杯[4,6]芳烃在 Cu 上的共价功能化，优化了各种合成方面以获得良好的覆盖率和铜钝化。通过 XPS 信号中特定元素的存在和相对定量证明了分子的粘附。我们通过用十一硫醇交换杯[4]芳烃成功地测试了不同功能的组合。在将杯[4]芳烃固定在 Cu 上之后，通过一系列摄取和释放循环来证明了杯[4]芳烃腔对进一步物种的可逆容纳能力，这些循环涉及吡啶盐。由上边缘带有 N-苯基脲基团的杯[6]芳烃轮和含有二茂铁的轴组成的轮烷和类轮烷物种通过轴的 SH 端固定在 Cu 上。XPS 证明了从溶液中完全组装的轮烷和类轮烷的成功自组装，以及在偏压下全轮烷和类轮烷轮的受控释放。
