Nanoscopic Assemblies between Supramolecular Redox Active Metallodendrons and Gold Nanoparticles: Synthesis, Characterization, and Selective Recognition of H2PO4-, HSO4-, and Adenosine-5‘-Triphosphate (ATP2-) Anions

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Abstract
Tri- and nonaferrocenyl thiol dendrons have been synthesized and used to assemble dendronized gold nanoparticles either by the ligand-substitution method from dodecanethiolate−gold nanoparticles (AB3 units) or Brust-type direct synthesis from a 1:1 mixture of dodecanethiol and dendronized thiol (AB9 units). The dendronized colloids are a new type of dendrimers with a gold colloidal core. Two colloids containing a nonasilylferrocenyl dendron have been made; they bear respectively 180 and 360 ferrocenyl units at the periphery. These colloids selectively recognize the anions H2PO4- and adenosine-5‘-triphosphate (ATP2-) with a positive dendritic effect and can be used to titrate these anions because of the shift of the CV wave even in the presence of other anions such as Cl- and HSO4-. Recognition is monitored by the appearance of a new wave at a less positive potential in cyclic voltammetry (CV). The anion HSO4- is also recognized and titrated by the dendronized colloid containing the tris-amidoferrocenyl units, because of the progressive shift of the CV wave until the equivalence point. These dendronized colloids can form robust modified electrodes by dipping the naked Pt electrode into a CH2Cl2 solution containing the colloids. The robustness is all the better as the dendron is larger. These modified electrodes can recognize H2PO4-, ATP2- and HSO4-, be washed with minimal loss of adsorbed colloid, and be reused.