Introduction. Fullerenes are fascinating carbon nanostructures that are not only aesthetically appealing but also have outstanding structural, magnetic, superconducting, electrochemical, and photochemical properties with great potential in both material science and applications. 1, 2 However, the poor compatibility of pristine fullerenes with other materials severely limits their derivatization and utilization. Despite the diverse routes to functionalize fullerenes, 1c only a few are highly efficient and specific. 3 This is especially the case for polymers. 4-6 The often unavoidable multiple addition and the reactive nature of fullerene to various reaction intermediates always leads to a mixture of homopolymer, monoadducts, and multiadducts, which, unlike small molecules, are often difficult to purify. Moreover, the reduced chain end reactivity in polymers (such as azides6) might sometimes require drastic reaction conditions (high temperature, long time, etc.), which could lead to potential polymer backbone degradation. 6c Also, some derivatives are unstable either by themselves (eg, retro-DA reaction) 1c or with singlet oxygen generated by [60] fullerene (eg, azafulleroid). 7 All of these can complicate the study of the physics of fullerene polymers. Our interest lies in the area of self-assembly in solution including crystallization of the polymer moiety to form a single crystal with two-dimensional arrays of the fullerene on the crystal surface. Thus, as part of our effort to manipulate fullerenes within the polymer paradigm, we wish to develop a strategy to create stable, well-defined fullerene materials under mild reaction conditions.

The concept of “click chemistry” has received enormous attention and has generated a considerable impact in material science since its reinvention in 2001. 8 The idea is to generate materials from a simple set of “click” reactions that are of high efficiency and technical simplicity, as demonstrated by the Cu-(I)-catalyzed [3+ 2] Huisgen cycloaddition reaction between an azide and a terminal alkyne to form a 1, 4-substituted 1, 2, 3-triazole. 9 Taking advantage of this reaction, we should be able to use terminal alkyne-functionalized fullerenes (thus named “Fulleryne” for the sake of simplicity), instead of pristine fullerene, to introduce fullerene into polymers in a “click” fashion (Scheme 1).