Divergent Growth of Coordination Dendrimers on Surfaces

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• 作者：Meni Wanunu ; Alexander Vaskevich ; Abraham Shanzer ; and Israel Rubinstein
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：June 28, 2006
• 年：2006
• 卷：128
• 期：25
• 页码：8341 - 8349
• 全文大小：473K
• 年卷期：v.128,no.25(June 28, 2006)
• ISSN：1520-5126

文摘

Divergent growth of surface-initiated dendritic nanostructures on gold surfaces in a highlycontrolled, stepwise manner is demonstrated, using metal-organic coordination as the binding motif. Therepeat unit for dendrimer growth was a branched, C₃-symmetrical ligand building block bearing three bis-hydroxamate groups. The surface initiation sites for dendrimer growth were obtained by the formation ofa mixed monolayer comprising isolated bis-hydroxamate disulfide anchor ligands and octanethiol (OT) atvery low anchor/OT ratios. Following functionalization of the surface with spaced anchors, alternateimmersion in solutions of Zr⁴⁺ ions and the branched ligand afforded surface-confined dendrimers ofincreasing generation, where the number of generations is conveniently controlled by the number ofcoordination binding sequences. The heights of different generation dendrimers are in excellent agreementwith values predicted by molecular models, as well as with thicknesses of branched multilayers preparedby the same procedure on full anchor monolayers. At higher generation numbers, gradual dendrimer overlapand coalescence are observed, eventually resulting in a continuous overlayer and a transition from 3D to1D growth. A mechanism for the development of dendritic coordination nanostructures on surfaces isdiscussed.