Atomic force microscopy dendrimer molecules

To characterize dendrimers, analytical methods used in synthetic organic chemistry as well as in macromolecular chemistry can be applied. Mass spectrometry and NMR spectroscopy are especially useful tools to estimate purity and structural perfection. To get an idea of the size of dendrimers, direct visualization methods such as atomic force microscopy (AFM) and transmission electron microscopy (TEM), or indirect methods such as size exclusion chromatography (SEC) or viscosimetry, are valuable. Computer aided simulation also became a very useful tool not only for the simulation of the geometry of a distinct molecule, but also for the estimation of the dynamics in a dendritic system, especially concerning mobility, shape-persistence, and end-group disposition. 

Dendrimers are large molecules, and their solubility is often an issue. Thus, it is not surprising that dendrimers can be good candidates to precipitate upon and thus modify the surface of an electrode. Dendrimers with ferrocenyl peripheral units were shown to display well-defined redox waves with the ferrocenyl units oxidizing independently.176-178 These molecules oxidatively precipitated onto the electrode surface and were characterized electrochemically and by atomic force microscopy.44 It was later shown that cyclodextrin complexation increased the solubility of these molecules.179 Similar results were obtained with dendrimers containing pendant ruthenium tris (bipyridine) and bis(terpyridine) groups.180... 

J. Li, D. R. Swanson and D. Qin et al, Characterizations of coreshell tecto-(dendrimer) molecules by tapping mode atomic force microscopy. Langmuir, 15(21), 7347-7350 (1999). 

Zhang, H., Grim, P.C.M., Foubert, P. et al. (2000) Properties of single dendrimer molecules studied by atomic force microscopy. Langmuir, 16,9009-9014. 

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