Balancing Attraction and Repulsion: The Influence of London Dispersion in [10]Cycloparaphenylene-Fullerene Complexes.

Herein we present a systematic study of the influence of different alkyl chains in malonyl ester fullerene adducts with [10]cycloparaphenylene ([10]CPP]) and a tert-butyl (tBu) ester-substituted [10]CPP analogue. The association constants between the nanoring hosts and the fullerene guests were determined by fluorescence quenching experiments. The trends in association were rationalized by an interplay of repulsion arising from an extended volume and London dispersion as an attractive counterpart.

Cycloparaphenylenes via [2+2+2] cycloaddition.

The [2+2+2] cycloaddition (CA) offers great potential as an atom economic method for the formation of substituted aromatic rings. In this article, we highlight the application of this versatile method in synthetic approaches towards substituted cycloparaphenylenes (CPPs). The [2+2+2] CA can take over different tasks within the synthesis depending on the targeted CPP. These approaches were divided into three key steps: aromatization (which finalises the CPP), macrocyclization (the formation of a strain-reduced macrocycle) and the [2+2+2] CA. Based on this analysis the strategies were categorised into four classes based on which task the [2+2+2] CA fulfills. We point out the benefits and drawbacks of each synthesic strategy and summarize our findings to provide the reader with an easy insight into this research field.

Robust coherent spin centers from stable azafullerene radicals entrapped in cycloparaphenylene rings.

Molecular entities with robust spin-1/2 are natural two-level quantum systems for realizing qubits and are key ingredients of emerging quantum technologies such as quantum computing. Here we show that robust and abundant spin-1/2 species can be created in situ in the solid state from spin-active azafullerene C59N cages supramolecularly hosted in crystals of [10]cycloparaphenylene ([10]CPP) nanohoops. This is achieved via a two-stage thermally-assisted homolysis of the parent diamagnetic [10]CPP⊃(C59N)2⊂[10]CPP supramolecular complex. Upon cooling, the otherwise unstable C59N˙ radical is remarkably persistent with a measured radical lifetime of several years. Additionally, pulsed electron paramagnetic resonance measurements show long coherence times, fulfilling a basic condition for any qubit manipulation, and observed Rabi oscillations demonstrate single qubit operation. These findings together with rapid recent advances on the synthesis of carbon nanohoops offer the potential to fabricate tailored cycloparaphenylene networks hosting C59N˙ centers, providing a promising platform for building complex qubit circuits.

Directed C-H Bond Oxidation of Bridged Cycloalkanes Catalyzed by Palladium(II) Acetate.

We have developed a synthesis of 1,2-substituted adamantane carboxylic acids and further bridged cycloalkanes (cage compounds) by palladium acetate-catalyzed C-H bond oxidation. Acetoxylation of cycloalkane framework was performed using picolylamide as a directing group. Modification of the substrate, ligand design and variation of reaction conditions enabled us to study the mechanism of acetoxylation of aliphatic compounds. Post-functionalization reactions and cleavage of the directing group were developed. For the first time the synthesis and characterization of a ß-C3 -tri-substituted adamantane derivatives was achieved.