We employed oleylphosphonic acid (OLPA) for the synthesis of CsPbBr₃ nanocrystals (NCs). Compared to phosphonic acids with linear alkyl chains, OLPA features a higher solubility in apolar solvents, allowing us to work at lower synthesis temperatures (100 °C), which in turn offer a good control over the NCs size. This can be reduced down to 5.0 nm, giving access to the strong quantum confinement regime. OLPA-based NCs form stable colloidal solutions at very low concentrations (∼1 nM), even when exposed to air. Such stability stems from the high solubility of OLPA in apolar solvents, which enables these molecules to reversibly bind/unbind to/from the NCs, preventing the NCs aggregation/precipitation. Small NCs feature efficient, blue-shifted emission and an ultraslow emission kinetics at cryogenic temperature, in striking difference to the fast decay of larger particles, suggesting that size-related exciton structure and/or trapping-detrapping dynamics determine the thermal equilibrium between coexisting radiative processes.

This perspective aims at celebrating the 100th anniversary of the discovery of the Passerini three component reaction.

Tetra- and octavalent sialoside clusters were prepared in good yields exploiting for the first time the multiple copper-catalyzed cycloaddition of a propargyl thiosialoside with calix[4]arene polyazides. The cycloadducts featured the hydrolytically stable carbon-sulfur bond at the anomeric position and the 1,4-disubstituted triazole ring as the spacer between the sialic acid moieties and the platform. It was demonstrated that these unnatural motifs did not hamper the desired biological activity of the sialoclusters. In fact, they were able to inhibit, at submillimolar concentrations, the hemagglutination and the viral infectivity mediated both by BK and influenza A viruses.