Halogen bonding (XB) between (iodoethynyl)benzene donors and quinuclidine in benzene affords binding free enthalpies (ΔG, 298 K) between -1.1 and -2.4 kcal mol(-1), with a strong LFER with the Hammett parameter σpara. The enthalpic driving force is compensated by an unfavorable entropic term. The binding affinity of XB acceptors increases in the order pyridine < C═O < S═O < P═O < quinuclidine. Diverse XB packing motifs are observed in the solid state.

Potassium acyltrifluoroborates (KATs) are increasingly important functional groups,a nd general methods for their preparation are of great current interest. We report abifunctional iminium reagent bearing both atin nucleophile and at rifluoroborate,w hichw as applied in chemoselective Pd 0 -catalyzed Migita-Kosugi-Stille cross-coupling reactions owitha ryl and vinyl halides.T his method gives access to previously inaccessible aromatic and a,b-unsaturated acyltrifluoroborates,i ncluding precursors to amino-acid derived KATs.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme 4. Analysis on the effect of copper. Scheme 5. Direct synthesis of a-aminotrifluoroborates from aryl iodides. Scheme 3. Synthesis of amino acid derived KATs by hydrogenation. Angewandte Chemie Communications

The ability to optically induce biological responses in 3D has been dwarfed by the physical limitations of visible light penetration to trigger photochemical processes. However, many biological systems are relatively transparent to low‐energy light, which does not provide sufficient energy to induce photochemistry in 3D. To overcome this challenge, hydrogels that are capable of converting red or near‐IR (NIR) light into blue light within the cell‐laden 3D scaffolds are developed. The upconverted light can then excite optically active proteins in cells to trigger a photochemical response. The hydrogels operate by triplet–triplet annihilation upconversion. As proof‐of‐principle, it is found that the hydrogels trigger an optogenetic response by red/NIR irradiation of HeLa cells that have been engineered to express the blue‐light sensitive protein Cry2olig. While it is remarkable to photoinduce the clustering of Cry2olig with blanket NIR irradiation in 3D, it is also demonstrated how the hydrogels trigger clustering within a single cell with great specificity and spatiotemporal control. In principle, these hydrogels may allow for photochemical control of cell function within 3D scaffolds, which can lead to a wealth of fundamental studies and biochemical applications.

A one-step synthesis of aliphatic KATs from organocuprates is reported. Organolithium and organomagnesium reagents were readily transmetalated onto Cu(I) and coupled with a KAT-forming reagent to yield the respective aliphatic KAT. The protocol is suitable for primary, secondary and-for the first time-tertiary alkyl substrates. These protocols considerably expand the range of KATs that can be readily accessed in one step from commercially available starting materials.

Acylboron compounds are emerging as versatile functional groups with applications in multiple research fields. Their synthesis, however, is still challenging and requires innovative methods. This Minireview provides an overview on the obstacles of acylboron synthesis and highlights notable advances within the last three years on new strategies to overcome the challenges posed by the formation of acyl–boron bonds.