Cyclotriveratrylene Dendrimers
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Cyclotriveratrylene Dendrimers Sanchez-Montes Karla E.,1 Klimova Tatiana,2 Martínez-Klimov Mark E.,2 Martínez-García Marcos. 1* 1
Instituto de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, Circuito Exterior, Coyoacán, C.P. 04510, México D.F. E-mail: [email protected] 2 Facultad de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, Circuito Interior, Coyoacán, C.P. 04510, México D.F. ABSTRACT Dendrons with dodecyl ended groups joined benzyloxy moieties were attached to a cyclotriveratrylene core. The dendrimers were used in Diederich cyclopropanation reaction with the fullerene C60. The structure of the synthesized dendrimers was confirmed by 1H- and 13C-NMR, MALDI-TOF mass spectrometry and elemental analysis. Keywords: Cyclotriveratrylene; dendrimers; fullerene C60
INTRODUCTION The cup-shape cyclotriveratrylene derivatives (CTV) are among the key structures, they have been exploited for many years for the design of molecular hosts1. They still represent interesting starting compounds for the construction of new macromolecular architectures such as solid inclusion complexes2, biosensors, chiroptical properties3 chiral scaffolds for triple helix formation4, organo- or metallo-gels5, H2 storage targets6 or more recently, coordination polymer networks7 and self- assembled monolayers on gold surface8 and dendrimers9. The tree or six p-hydroxybenzyl substituent present on the wider rim of cyclotriveratrylenes are able suffer modification to obtain dendrimers without steric restrictions. Now we report the synthesis of cyclotriveratrylene-dendrimers with three and six fullerenes in the dendritic branches. EXPERIMENT Materials and equipments Solvents and reagents were purchased as reagent grade and used without further purification. Acetone was distilled over calcium chloride. Tetrahydrofuran was distilled from sodium and benzophenone. Column chromatography was performed on Merck silica gel 60Å (70-230 mesh). 1H- and 13C-NMR were recorded on a VarianUnity-300 MHz with tetramethylsilane (TMS) as an internal reference. Infrared (IR) spectra were measured on a spectrophotometer Nicolet FT-SSX. Elemental analysis was determined by Galbraith Laboratories Inc. (Knoxville, TN, USA). FAB+ mass spectra were taken on a JEOL JMS AX505 HA instrument. Electrospray mass spectra were taken on a Bruker Daltonic, Esquire 6000. MALDI-TOF mass spectra were taken on a Bruker Omni FLEX. Synthesis of dendrimers 69
A mixture of 12 or 14 (0.36 mmol), cesium carbonate (0.36 mmol) in N,Ndimethylformamide anhydrous (8 ml) was heated to reflux and stirred vigorously under nitrogen after 20 min. The cyclotriveratrylene 3 (0.07 mmol) dissolved in N,Ndimethylformamide anhydrous (10 ml) was added dropwise and the reaction was continued for 31 h at reflux. The mixture was allowed to cool and the precipitate was filtered. The filtrate was evaporated to dryness under reduced pressure and the residue was chromatographed on silica gel with ethyl hexane as the eluent to afford the cyclotriveratrylene-dendrim
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