Practical Synthesis of [n]Cycloparaphenylenes (n=5, 7-12) by H2SnCl4-Mediated Aromatization of 1,4-Dihydroxycyclo-2,5-diene Precursors

Synthesis, Properties, and Design Principles of Donor-Acceptor Nanohoops

We have synthesized a series of aza[8]cycloparaphenylenes containing one, two, and three nitrogens to probe the impact of nitrogen doping on optoelectronic properties and solid state packing. Alkylation of these azananohoops afforded the first donor-acceptor nanohoops where the phenylene backbone acts as the donor and the pyridinium units act as the acceptor. The impact on the optoelectronic properties was then studied experimentally and computationally to provide new insight into the effect of functionalization on nanohoops properties.

π-extended [12]cycloparaphenylenes: from a hexaphenylbenzene cyclohexamer to its unexpected C2-symmetric congener

Based on a π-extended [12]CPP, two different precursors for the bottom-up synthesis of CNTs were synthesized. The congested hexaphenylbenzene mode of connectivity of the two macrocycles reveals an improved oxidative cyclodehydrogenation over previous reported strategies.

The synthesis of π-extended [12]cycloparaphenylene (CPP) derivatives from a kinked triangular macrocycle is presented. Depending on the reaction conditions for reductive aromatization, either a hexaphenylbenzene cyclohexamer or its C₂-symmetric congener was obtained. Their structures were confirmed by NMR spectroscopy or X-ray crystallographic analysis. With the support of DFT calculations, a mechanistic explanation for the unexpected formation of the oval shaped bis(cyclohexadiene)-bridged C₂-symmetric macrocycle is provided. The here employed congested hexaphenylbenzene mode of connectivity in conjunction with a non-strained precursor improves oxidative cyclodehydrogenation toward the formation of ultrashort carbon nanotubes (CNT)s. Thus, this strategy can pave the way for new conceptual approaches of a solution-based bottom-up synthesis of CNTs.