Synthesis, Resolution, and Absolute Configuration of a Phosphine-Based Hemicryptophane Cage with an Endo Phosphorus Lone Pair and Formation of the Corresponding Gold Complex.

The synthesis, characterization, and chiroptical properties of a new class of hemicryptophanes combining a phosphine moiety and a cyclotriveratrylene unit are reported. The synthesis was short and efficient. The racemic mixture of the cage was resolved by chiral high-performance liquid chromatography (HPLC), giving access to enantiopure molecular cages, whose absolute configurations could be assigned by electronic circular dichroism (ECD) spectroscopy. These new phosphines were then reacted with gold in order to make the corresponding enantiopure gold complexes. The X-ray structure reveals an endohedral functionalization of the cage with the gold metal entrapped in the heart of the cavity, leading to a Vbur of 58%. Moreover, the chirality of the cyclotriveratrylene unit was found to control the chiral arrangement of the aryl group linked to the phosphorus atom, located at the opposite side of the cavity.

Singlet Oxygen Responsive Molecular Receptor to Modulate Atropisomerism and Cation Binding.

In switchable molecular recognition, 1 O2 stimulus responsive receptors offer a unique structural change that is rarely exploited. The employed [4+2] reaction between 1 O2 and anthracene derivatives is quantitative, reversible and easily implemented. To evaluate the full potential of this new stimulus, a non-macrocyclic anthracene-based host was designed for the modular binding of cations. The structural investigation showed that 1 O2 controlled the atropisomerism in an on/off fashion within the pair of hosts. The binding studies revealed higher association constants for the endoperoxide receptor compared to the parent anthracene, due to a more favoured preorganization of the recognition site. The fatigue of the 1 O2 switchable hosts and their complexes was monitored over five cycles of cycloaddition/cycloreversion.

Tetrameric self-assembling of water-lean solvents enables carbamate anhydride-based CO2 capture chemistry.

Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO2-containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO2.