Intravesicular and intervesicular interaction by orthogonal multivalent host-guest and metal-ligand complexation

Lim, Choon Woo and Crespo-Biel, Olga and Stuart, Marc C.A. and Reinhoudt, David N. and Huskens, Jurriaan and Ravoo, Bart Jan (2007) Intravesicular and intervesicular interaction by orthogonal multivalent host-guest and metal-ligand complexation. Proceedings of the National Academy of Sciences of the United States of America, PNAS, 104 (17). 6986-6991 . ISSN 0027-8424

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Abstract:	Host vesicles composed of amphiphilic beta-cyclodextrin CD1 recognize metal-coordination complexes of the adamantyl-functionalized ethylenediamine ligand L via hydrophobic inclusion in the beta-cyclodextrin cavities at the vesicle surface. In the case of Cu(II) and L, the resulting coordination complex was exclusively CuL2, and the interaction with the host vesicles was intravesicular, unless the concentration of metal complex and vesicles was high (>0.1 mM). In the case of Ni(II) and L, a mixture was formed consisting of mainly NiL and NiL2, the interaction with the host vesicles was effectively intervesicular, and addition of the guest-metal complex resulted in aggregation of the vesicles into dense, multilamellar clusters even in dilute solution [1 µM Ni(II)]. The metal-L complex could be eliminated by a strong chelator such as EDTA, and the intervesicular interaction could be suppressed by a competitor such as unmodified beta-cyclodextrin. The result from this investigation is that the strongest metal-coordination complex [Cu(II) with L] binds exclusively intravesicularly, whereas the weakest metal-coordination complex [Ni(II) with L] binds predominantly intervesicularly and is the strongest interfacial binder. These experimental observations are confirmed by a thermodynamic model that describes multivalent orthogonal interactions at interfaces.
Item Type:	Article
Copyright:	© 2007 PNAS
Faculty:	Science and Technology (TNW)
Research Group:	Molecular Nanofabrication (MNF)
Link to this item:	http://purl.utwente.nl/publications/58138
Official URL:	http://dx.doi.org/10.1073/pnas.0611123104
Supplementary information URL:	http://www.pnas.org/cgi/content/full/0611123104/DC1
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Metis ID: 241419