“Janus” Calixarenes: Double-Sided Molecular Linkers for Facile, Multianchor Point, Multifunctional, Surface Modification

Abstract

We herein report the synthesis of novel “Janus” calix[4]arenes bearing four “molecular tethering” functional groups on either the upper or lower rims of the calixarene. These enable facile multipoint covalent attachment to electrode surfaces with monolayer coverage. The other rim of the calixarenes bear either four azide or four ethynyl functional groups, which are easily modified by the copper(I)-catalyzed azide–alkyne cycloaddition reaction (CuAAC), either pre- or postsurface modification, enabling these conical, nanocavity reactor sites to be decorated with a wide range of substrates to impart desired chemical properties. Redox active species decorating the peripheral rim are shown to be electrically connected by the calixarene to the electrode surface in either “up” or “down” orientations of the calixarene.

Controlled Functionalization of Gold Nanoparticles with Mixtures of Calix[4]arenes Revealed by Infrared Spectroscopy

“…37,38 However, this can be prevented by using calix [4]arene-tetra-diazonium compounds whose structure and geometry do not allow any additional grafting. 39,40 These cone-shaped macrocycles can be grafted via multiple C-Au bonds, leading to a remarkably robust ligand shell on surfaces and on AuNPs. 39,41 Furthermore, because the grafting of these calix [4]arenes via C-Au bonds is irreversible, homogeneous mixtures of calixarenes can be grafted.…”

Robust hydrophobic gold, glass and polypropylene surfaces obtained through a nanometric covalently bound organic layer

“…1). 4,[40][41][42][43][44][45][46][47] Calix [4]arenes are macrocycles composed of four phenolic units that are parasubstituted and linked in the ortho position through methylene bridges. These methylene bridges prevent polymerization of the diazonium derivatives, and hence lead solely to formation of monolayers.…”

Anodic Oxidation of Ethynylferrocene Derivatives in Homogeneous Solution and Following Anodic Deposition onto Glassy Carbon Electrodes

“…Recently it has been shown that radical‐based electrografting processes are effective in preparing chemically modified electrodes to which molecules are covalently attached through an ethynyl group . We have previously described an assortment of methods whereby metallocenes derivatized at a cyclopentadienyl ring with a terminal ethynyl group can be covalently attached to carbon surfaces .…”

“…New directions and applications of anodic ethynyl deposition methods have already begun to appear. These include the depositions of a nickel cyclam complex that is an effective catalyst for CO 2 reduction, using the direct oxidation method, and several calixarenes anchored through multiple ethynyl groups, using the lithio activation method . Both Sheridan et al .…”