Controlled Polymerization of Norbornene Cycloparaphenylenes Expands Carbon Nanomaterials Design Space

Abstract

Carbon-based materials—such as graphene nanoribbons, fullerenes, and carbon nanotubes—elicit significant excitement due to their wide-ranging properties and many possible applications. However, the lack of methods for precise synthesis, functionalization, and assembly of complex carbon materials has hindered efforts to define structure–property relationships and develop new carbon materials with unique properties. To overcome this challenge, we employed a combination of bottom-up organic synthesis and controlled polymer synthesis. We designed norbornene-functionalized cycloparaphenylenes (CPPs), a family of macrocycles that map onto armchair carbon nanotubes of varying diameters. Through ring-opening metathesis polymerization, we accessed homopolymers as well as block and statistical copolymers constructed from “carbon nanohoops” with a high degree of structural control. These soluble, sp 2 -carbon-dense polymers exhibit tunable fluorescence emission and supramolecular responses based on composition and sequence. This work represents an important advance toward bridging the gap between small molecules and functional carbon-based materials.

Photoinduced electron transfer in host–guest complexes of double nanohoops

“…The variability in the size of nanohoops has led to their wide application in supramolecular chemistry [5,6]. A change in size dramatically affects their photophysical properties [7][8][9]. The first host-guest complex of CPP was reported by Iwamoto et al in 2011 [10].…”

Fullerene Wires Assembled Inside Carbon Nanohoops

“…In addition, the norbornene‐embedded CPP polymers are potential hosts for fullerenes or metallofullerenes and the corresponding complexes are of interest as organic materials for applications in electronics and spintronics. [50] …”

Synthesis and metalation of polycatechol nanohoops derived from fluorocycloparaphenylenes

“…8 Recently, spurred by new advances in the synthetic chemistry of CPPs, 4,[9][10][11] functionalized CPPs have also been explored as monomers for the synthesis of novel polymers via crosscoupling 12,13 and ring-opening metathesis polymerization strategies. 14 However, despite tremendous strides in CPP-based materials chemistry, the initial vision of using CPPs for the bottom-up synthesis of well-dened nanotubular structures has yet to be fully realized. For example, CPP-templated carbon nanotubes still display a distribution of diameters, chiralities, and wall thicknesses.…”