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 polarised optical, fluorescence and scanning electron microscopy. The resulting information indicates that different types of interactions are present with the two different guest molecules. In the case of HMP, the compounds aggregate giving rise to larger structures, favouring 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 organised in a parallel way (head to head interactions organised by the presence of the oligonucleotide).

Keywords:

• Molecular recognition
• gold(I)
• oligonucleotides
• spectroscopy
• microscopy
• DLS

Acknowledgements

Financial support by the Spanish MINECO and FEDER funds from the European Union are gratefully acknowledged (project AEI/FEDER, UE CTQ2016-76120-P). This work was also supported by the Associated Laboratory for Sustainable Chemistry-Clean Processes and Technologies-LAQV, which is financed by national funds from FCT/MEC (UID/QUI/50,006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265). N.S. is indebted to Erasmus Exchange Program. This research was supported by a Marie Curie Intra-European Fellowship within the 7th European Community Framework Programme (R. G.).