FaFrit

Whereas tris(trifluoromethyl)silanes tend to decompose violently at room temperature, the corresponding pentafluoroethyl derivatives are thermostable compounds. Preparative synthesis of Li[Si(C₂F₅)₃] enabled efficient nucleophilic transfer of the Si(C₂F₅)₃ unit onto main-group and transition-metal compounds as well as organic scaffolds, as shown by B. Hoge and co-workers in two Communications on page 16156 ff. and on page 16161 ff.

Herein we report the organoplatinum-mediated bottom-up synthesis, characterization, and properties of a novel large π-extended carbon nanoring based on a nanographene hexa-peri-hexabenzocoronene (HBC) building unit. This tubular structure can be considered as an example of the longitudinal extension of the cycloparaphenylene scaffold to form a large π-extended carbon nanotube (CNT) segment. The cyclic tetramer of a tetramesityl HBC ([4]CHBC) was synthesized by the reaction of a 2,11-diborylated hexa-peri-hexabenzocoronene with a platinum complex, followed by reductive elimination. The structure of this tubular molecule was further confirmed by physical characterization. Theoretical calculations indicate that the strain energy of this nanoring is as high as 49.18 kcal mol⁻¹. The selective supramolecular host–guest interaction between [4]CHBC and C₇₀ was also investigated.

A decent slice of a carbon nanotube was synthesized in the form of a large π-extended carbon nanoring based only on hexa-peri-hexabenzocoronene units (see picture). The photophysical properties of the nanoring were investigated by both steady-state and time-resolved fluorescence spectroscopy, and a selective supramolecular host–guest interaction with C₇₀ was identified.

Guest encapsulation underpins the functional properties of self-assembled capsules yet identifying systems capable of strongly binding small organic molecules in solution remains a challenge. Most coordination capsules rely on the hydrophobic effect to ensure effective solution-phase association. In contrast, we show that using non-interacting anions in apolar solvents can maximize favorable interactions between a cationic Pd₂L₄ host and charge-neutral guests resulting in a dramatic increase in binding strength. With quinone-type guests, association constants in excess of 10⁸ m⁻¹ were observed, comparable to the highest previously recorded constant for a metallosupramolecular capsule. Modulation of optoelectronic properties of the guests was also observed, with encapsulation either changing or switching-on luminescence not present in the bulk phase.

Molecular encapsulation: A combination of apolar solvents and weakly interacting anions has been used to maximize the non-covalent interactions between a simple Pd₂L₄ host and various charge-neutral guest molecules, leading to some of the highest association constants ever reported for a coordination capsule system.

Macrocyclic compounds have been extensively studied because of their widespread applications. Most classical macrocyclic compounds are planar molecules. In their Communication on page 14590 ff., L. B. Gan and co-workers report a N,O-heterocycle created on the C₆₀ cage skeleton through a multistep procedure, which includes repeated PCl₅-induced hydroxylamino N−O bond cleavage, and also piperidine-induced peroxo O−O bond cleavage. The fullerene-based macrocycle showed unique reactivity towards fluoride ions and copper salts.