The explosively-growing applications of the Cu-catalyzed Huisgen 1,3-dipolar cycloaddition reaction between organic azides and alkynes (CuAAC) have stimulated an impressive number of reports, in the last years, focusing on recoverable variants of the homogeneous or quasi-homogeneous catalysts. Recent advances in the field are reviewed, with particular emphasis on systems immobilized onto polymeric organic or inorganic supports.

We report the synthesis of chiral lanthanide complexes with extended π conjugation for efficient circularly polarized luminescence (CPL) via two-photon excitation (2PE). The pyridine bis-oxazoline (PyBox) core provides the chiral Ln³⁺ environment, while the extension of the conjugated backbone through the pyridine 4-position with a phenylacetylene unit increases the two-photon absorption cross section. This work presents an important step toward the development of chiral systems displaying enhanced nonlinear optical properties, with potential applications in imaging and sensing, as well as in photodynamic therapy due to the selective excitation of molecules within a specific focal volume.

Novel chiral Er complexes based on both enantiomers of extended ⁱPrPyBox (2,6‐Bis[4‐isopropyl‐4,5‐dihydrooxazol‐2‐yl)]pyridine) show strong near‐infrared circularly polarized luminescence (CPL) within the 1400 to 1600 nm spectral region under 450 nm irradiation. CPL activity in this region, despite being particularly rare, would open the way to potential applications in the domain, e.g., of fiber‐optic telecommunications and free‐space long‐distance optical communications employing circularly polarized light. Moreover, the long wavelength excitation is advantageous for applications in the field of (circularly polarized) microscopy and bioimaging.

BACKGROUND: Several essential oils, including citronella (lemongrass, Cymbopogon sp., Poaceae), are well‐known mosquito repellents. A drawback of such products is their limited protection time resulting from the high volatility of their active components. In particular, citronella oil protects for <2 h, although formulations with fixatives can increase this time.RESULTS: We synthesized hydroxylated cyclic acetals of citronellal, the main component of citronella, to obtain derivatives with lower volatility and weaker odour. The crude mixture of isomers obtained in the reaction was tested under laboratory conditions for its repellency against two mosquito species, the major malaria vector Anopheles gambiae and the arbovirus vector Aedes albopictus, and found to be endowed with longer protection time with respect to DEET (N,N‐diethyl‐meta‐toluamide) at the same concentration. Formulated products were tested in a latin square human field trial, in an area at a high density of A. albopictus for 8 h from the application. We found that the performance of the citronellal derivatives mixture is comparable (95% protection for ≤3.5 h) with those of the most widespread synthetic repellents DEET and Icaridin, tested at a four‐fold higher doses.CONCLUSIONS: Modifying the hydrophilicity and volatility of natural repellents is a valuable strategy to design insect repellents with a long‐lasting effect. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The lack of supported versions of the tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) ligand, suitable for flow-chemistry applications at scale, prompted us to develop a new route for the immobilization of such tris-triazole chelating units on highly cross-linked polystyrene resins. With this aim, the preparation of the known TBTA-type monomer 3 was optimized to develop a high-yield synthetic sequence, devoid of chromatographic purifications at any stage. Then, bead-type (P7) and monolithic (M7) functional resins were obtained by the easy and scalable suspension- or mold-copolymerization of 3 with divinylbenzene. Both types of materials were found to possess a highly porous morphology and specific surface area in the dry state and could be charged with substantial amounts of Cu(I) or Cu(II) salts. After treatment of the latter with a proper reducing agent, the corresponding supported Cu(I) complexes were tested in the copper-catalyzed alkyne-azide cycloaddition reaction (CuAAC). The immobilized catalysts proved active at room temperature and, in batch and with catalyst loadings as low as 0.6 mol%, afforded quantitative conversions within 20 h. Independent of the alkyne structure, extended use of the supported catalyst in flow was also possible. In the reaction of benzylazide and propargyl alcohol, this allowed a total turnover number larger than 400 to be reached.