(Invited) Large π-Extended Carbon Crowns and Cylinders As Conjugated Segments of Single-Walled Carbon Nanotubes

摘要

Carbon exists as a variety of nanometer-sized allotropes, such as OD fullerenes, 1D carbon nanotubes (CNTs), and 2D graphene. So far, it is still a great challenge to construct CNTs with a fixed length and diameter-specified single-chirality. In this talk, we will discuss synthesis and properties of a series of novel large π-extended molecular carbon crowns and cylinders as a finite model of single-walled CNTs, including TCR, HCR, and their C_(60) complexes et al. The nanographene HBC unit can be facilely embedded into cycloparaphenylene rings by Pd-mediated coupling reactions and the structure can be confirmed by crystal structure. Their macrocyclic structures of these nanocarbons have also been characterized using various physical methods, including NMR, STM, PL, crystallographic analysis. The photophysical properties of these molecules are studied in solution and explained by theoretical calculations. In addition, the ring-shaped structure can be inserted into a poly(para-phenylene) backbone as a polymeric segment (PS1) of single-walled CNTs. PS1 is achieved by a rationally designed synthesis of a bifunctionalized cyclo-para-phenylene monomer, followed by inserting these ring-shaped units into the conjugated poly(para-phenylene) chain. All these π-extended nanocarbons can provide new insight for the development of bottom-up syntheses of uniform carbon nanotube segments and potential applications in electron- and hole-transport devices.