Template fullerene derivatives

Self-assembled monolayers of Cgo derivatives have been successfully obtained using thiol-functionalized fullerenes [29,79-82]. In a recent report, Echegoyen and collaborators used a LlO-phenanthroline-Cgo (phen-Cgo) adduct to form a self-assembled monolayer on Au(lll) (Schemes) [83]. However, whereas phen-Cgo alone did not form stable monolayers, very well ordered stacks were obtained using 1,10-phenanthroline as a template, within which the fullerene derivative intercalates very efficiently. The geometry of the packing seems to be controlled by the dimensions of the two partners, as the fullerene diameter is about 10 A and the phen-phen distance is approximately 1/3 (3.3 A). 

Polymer-templated fullerene nano-arrays can be produced using ionic interactions between charged polymers and fuUerene derivatives [93]. Schanze, Reynolds and coworkers have reported that the layer-by-layer self-assembly approach can be used to fabricate an active material layer made up of PPE-SOj 15, PPE-EDOT-SOJ 16 and [60]fullerene 17 for photovoltaic cells (EDOT = 3,4-ethylenedioxythiophene) (Figure 9.20) [94]. Multiple, layer-by-layer deposition of the polymers and com-... 

The scope of the tether-directed remote functionalization has been expanded from Cgo to the higher fullerene C70, and the described reactions are completely regioselective, featuring, in the case of C70, the kinetically disfavored addition pattern. The crown ether is a real template, since it can be readily removed by transesterification, giving a much-improved access to certain bis-adducts that are not accessible by the direct route. Cation-binding studies by CV reveal that cyclophane-type crown ethers derived from C60 and C70 form stable complexes with metal cations, and a perturbation of the fullerene reduction potentials occurs because the cation is tightly held close to the fullerene surface. This conclusion is of great importance for future developments of fullerene-based electrochemical ion sensors. 

Template-controlled regioselective biscycloaddition to [60]fullerene with formation of fused heterocyclic derivatives 03BCJ865. 

Hirsch and co-workers subsequently discovered that the yield of hexakis-adducts such as 8 or 9 can be greatly increased and their separation from side products substantially facilitated, if 9,10-dimethylanthracene (DMA) is used as a template (Scheme 7-2) [14, 15]. Anthracene derivatives such as DMA are well known to undergo reversible Diels-Alder additions with fullerenes at ambient temperamre [16-18]. After addition to the fullerene, the template directs diethyl malonate addends in the Bingel addition tegio-selectively into e positions, ultimately yielding the hexakis-adducts with a pseudo-octahedral, all-e addition pattern. The templated activation of e 6-6 bonds (bonds between two six-membered rings) is also efficient starting from C o mono-adducts, and several examples are shown in Scheme 7-2. Thus, bis(alkynyl)methanofullerene 10 [19] reacted with diethyl 2-bromomalonate/DBU (8 equiv) and DMA (12 equiv) to provide hexakis-... 

By modification of the Leigh protocol,electron donor Fc derivatives were added to a macrocycle in a fullerene-stoppered rotaxane (Figure 2.34). " The distance from the Fc units to the fullerene was important to increase the lifetimes of the radical pair species, which arise from 9 to 26 ns when a triethyleneglycol spacer was added between the 1,4-diamide template and Moreover, the addition of a component (hexafluoroisopropanol) able to distnrb the hydrogen bonds in the solution decreased the relative distance between the electron donors and the fullerene, together with the lifetimes of the radical pairs, reduced at 13 ns. This, together with other photophysical... 

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