Published: September 14, 2011 r2011 American Chemical Society 16758 dx.doi.org/10.1021/ja206769a | J. Am. Chem. Soc. 2011, 133, 16758–16761 COMMUNICATION pubs.acs.org/JACS Nanorods versus Nanovesicles from Amphiphilic Dendrofullerenes Antonio Mu~ noz, † Beatriz M. Illescas, † Macarena S  anchez-Navarro, †,‡ Javier Rojo,* ,‡ and Nazario Martín* ,†,§ † Departamento de Química Org  anica, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain ‡ Glycosystems Laboratory, Instituto de Investigaciones Químicas, CSIC - Universidad de Sevilla, Am erico Vespucio, 49. Isla de la Cartuja 41092 Sevilla, Spain § Instituto Madrile~ no de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Campus UAM, Cantoblanco, E-28049, Madrid, Spain b S Supporting Information ABSTRACT: Three new amphiphilic dendrofullerenes endowed with 4, 8, and 16 carboxylic groups have been efficiently prepared by using a click chemistry methodology. These amphiphilic fullerene derivatives aggregate forming micelles, nanorods, or hollow vesicles depending on the concentration and on the solid substrate. T he unique physical and chemical properties of fullerenes have been successfully used in the development of two main scientific areas, biological applications 1 and functional materials. 2 The first research topic requires working with water-soluble biocompatible materials, which has generated the evolution of strategies to overcome the natural hydrophobic character of fullerenes. 3 One of these strategies implies the use of dendritic fullerene derivatives. 4 On the other hand, the most promising applications of fullerene-based materials are related to the development of organic electronic devices, such as field effect transistors (OFETs) or solar cells (SCs). 5 In both fields, the study of self-organization of fullerene derivatives to obtain functional supramolecular architectures is nowadays an impor- tant scientific challenge. 6 Thus, for instance, the investigation of the aggregation of fullerene containing amphiphiles has led to the formation of micelles, vesicles, and other structures. 7 In some cases, this aggregation can be controlled by an external stimulus, such as pH, which could be useful for the design of targeted drug delivery systems. 8 Nakamura and co-workers have reported the formation of bilayer vesicles with small water permeability coefficient from nonpolar/polar/nonpolar amphiphiles consti- tuted by the potassium complexes of penta-substituted fullerene anions. 9 From the point of view of the construction of functional materials, it has been proved that a change in the morphology of the material can give rise to the modification of its physicochem- ical properties. Thus, the chiroselective assembly of a chiral porphyrinÀfullerene dyad has demonstrated a better ambipolar charge-carrier mobility for nanofibers obtained from the enan- tiopure compound than for the spherical aggregates resulting from the racemic dyad. 10 Guldi, Torres, Prato, and co-workers have reported the increased lifetime of the photogenerated charge- separated (CS) state resulting when a phthalocyanineÀC 60 am- phiphilic derivative (ZnPcÀC 60 ) is ordered into one-dimensional nanotubules. The ordered nanotubular structure showed a lifetime of the CS state (τ ∼ 1.4 ms) 6 orders of magnitude longer than that obtained for the monomeric ZnPcÀC 60 dyad (τ ∼ 3.0 ns). 11 Recently, the utility of copper-catalized azideÀalkyne cycload- dition (CuAAC) reaction to obtain highly functionalized fulle- rene derivatives has been demonstrated. 12 In this paper, we report on the synthesis of new amphiphilic dendrofullerenes (Figure 1) by using the above-mentioned click-chemistry meth- odology. The study of the aggregation behavior of such fullerene- based amphiphiles has shown the formation of nanorods, mi- celles, or vesicles depending on the nature of the solid substrate employed for the deposition of the dendrimeric fullerene solu- tions or on the concentration of this solution. The synthesis of fullerene dendrimers was carried out by Huisgen Cu-catalyzed coupling reaction of alkyne functionalized fullerene derivatives (1 and 2, see Supporting Information (SI)) with azide substituted dendrons endowed with a variable number Figure 1. Structure of new amphiphilic dendrofullerenes (DF) (number refers to the content of carboxylic groups). Received: July 20, 2011