Modulation of supramolecular gold(I) aggregates by anion's interaction

Abstract

The gold complexes [Au(4-pyridylethynyl)(PTA)] and [Au(4-pyridylethynyl)(DAPTA)] (PTA = 1,3,5-triaza-7-phosphaadamantane; DAPTA = 3,7-diacetyl-1,3,7-triaza-5- phosphabicyclo[3.3.1]nonane) were used as host in molecular recognition processes of sodium hexametaphosphate (HMP) and a single stranded 24-long oligonucleotide. Experiments were performed by absorption titrations and looking at the resulting host:guest adducts by polarized optical, fluorescence and scanning electron microscopy. The resulting information indicates that different type of interactions are present with the two different guest molecules. In the case of HMP, the compounds aggregate giving rise to larger structures, favoring exciton splitting coupling and the formation of head to tail interactions. In the case of oligonucleotide studies, the formation of smaller supramolecular structures is observed, with less contribution of aurophilic contacts and organized in a parallel way (head to head interactions organized by the presence of the oligonucleotide).