Analysis of Metallo-Supramolecular Systems Using Single-Molecule Force Spectroscopy

• Published in: Advanced functional materials 2003-08, Vol.13 (8), p.615-620
• Main Authors: Kudera, M., Eschbaumer, C., Gaub, H.E., Schubert, U.S.
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Rupture forces; Supramolecular chemistry
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200304359

Single‐molecule force spectroscopy has been used for the investigation of the rupture behavior of individual metallo‐supramolecular systems. For this purpose, a specifically designed unsymmetrical α,ω‐functionalized poly(ethylene oxide) has been employed for mono‐termination with a terpyridine ligand and subsequently for the attachment onto atomic force microscopy (AFM) tips and microscope slide substrates. Metallo‐supramolecular complexes were formed by the use of ruthenium(III)–ruthenium(II) chemistry. Vertical stretching with the AFM cantilever ruptured the coordinative bonds. The rupture force of individual bisterpyridine ruthenium(II) complexes was determined to be 95 pN at a force loading rate of 1 nN s–1. Simultaneous rupturing of multiple parallel metallo‐supramolecular bonds was also observed. Monte Carlo simulations corroborated the experimental observations. The presented results lay the basis for the application of such metallo‐supramolecular systems in advanced functional nanomaterials. Metallo‐supramolecular complexes have been investigated on the molecular level using single‐molecule force spectroscopy (see Figure and cover). The rupture force of an individual bisterpyridine ruthenium(II) complex was found to be 95 pN and thus comparable to biotin–streptavidin binding forces. Such systems are therefore particularly suited for the construction of functional nanomaterials.