Microwave-Assisted Synthesis of Dendritic Viologen-Arranged Molecules with an ω-Mercaptoalkyl Group and Their Self-Assembled Monolayers Complexed with Various Anions

We report unique self-assembled monolayers (SAMs) consisting of dendritic viologen-arranged molecules with an ω-mercaptodecyl group (An, n (dendritic generation) = 0–3) at the apex of the dendritic structure, which can accommodate a specific amount of metal anionic complexes defined by the dendritic structure. Dendritic molecules from several generations were successfully synthesized via microwave heating, thus providing easy access to third-generation molecules without requiring protection/deprotection processes during generation growth. SAMs of the dendritic molecules were fabricated by soaking gold substrates in solutions of the molecules in an acetonitrile/ethanol mixture at room temperature. Counter anions of the viologen units in the SAMs could be exchanged easily for various metal anionic complexes, such as PtCl42–, CuCl42–, and PdCl42–, by immersing the SAMs in aqueous solutions of the ions. X-ray photoelectron spectroscopy of the SAMs revealed that the amount of the metal anionic complexes accomm...