Self-assembly of dendrimers and macrocycles on the nanometre scale
Poster presentation: International Conference on Nanoscience and Technology: NANO9 meets STM06 (ICN+T 2006), July 30 – August 4, 2006, Basel, Switzerland
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Abstract:
The processing and the manipulation of complex architectures on the nano scale is one of the key issues towards a technology based on smart materials. In order to design efficient functional devices it is important to control the structure of organic materials down to the nanometre scale.
There are different ways to achieve such control, but most often they rely on some degree of programming of the elements to be assembled. The assembly code may be stored in the chemical structure of the elements or in the environment of the elements. Self-assembly of individual molecules can lead to formation of higher ordered structures such as fibers. In nature this phenomenon is abundantly present: formation of DNA double helix, collagen…
We gather information on the self-assembly of organic molecules on a surface, try to control this self-assembly, and examine the structures formed. To investigate the influence of the nature of the molecule on fiber formation, a variety of molecules (different structures and functionalities) were drop casted on a substrate and studied with atomic force microscopy (AFM). The organic molecules studied can be divided into two types: dendrimers [1] and macrocycles [2]. AFM measurements show that both the dendrimer (see figure) as well as the macrocycle can form fibers.
In case of the dendrimer, this is probably due to the interpenetration of branches of interacting dendrimers. The driving force for the formation of the fibers is attributed to the pi-pi and van der Waals interactions among dendrimer branches. For the macrocycle, the rigid core (pi-pi stacking) and alkyl groups guide the fiber formation.
[1] D. Liu, S. De Feyter, M. Cotlet, U.-M. Wiesler, T. Weil, A. Herrmann, K. Müllen and F. C. De Schryver, Macromolecules, 2003, 36, 22, 8489-8498
[2] A. Ziegler, W. Mamdouh, A. Ver Heyen, M. Surin, H. Uji-i, M. M. S. Abdel-Mottaleb, F. C. De Schryver, S. De Feyter, R. Lazzaroni and S. Höger, Chem. Mat., 2005, 17, 23, 56705683
