While pnictaalkenes are well‐established for the light group 15 elements, they become more reactive and exceptionally rare as the group is descended. Herein, we report a combined experimental and theoretical study on the first examples of carbodicarbene (CDC)‐stabilized bismuth complexes, which feature low‐coordinate cationic bismuth centers with C=Bi multiple bond character. Monocations [(CDC)Bi(Ph)Cl][SbF₆] (8) and  [(CDC)BiBr₂(THF)₂][SbF₆] (11), dications [(CDC)Bi(Ph)][SbF₆]₂ (9) and [(CDC)BiBr(THF)₃][NTf₂]₂ (12), and trication [(CDC)₂Bi][NTf₂]₃ (13) have been synthesized via sequential halide abstractions from (CDC)Bi(Ph)Cl₂ (7) and (CDC)BiBr₃ (10). Notably, the dications and trication exhibit C⇉Bi double dative bonds, and thus represent unprecedented bismaalkene cations. In addition, the synthesis of these species highlights a unique non‐reductive route to C–Bi π‐bonding character. The CDC‐[Bi] complexes (7‐13) were compared with related NHC‐[Bi] complexes (1, 3‐6) and show substantially different structural properties. Indeed, the CDC ligand has a remarkable influence on the overall stability of the resulting low‐coordinate Bi complexes, suggesting that CDC is a superior ligand to NHC in heavy pnictogen chemistry. All compounds have been characterized by multiple analytical methods including ¹H and ¹³C NMR, X‐ray crystallography, elemental analysis, and UV‐Vis spectroscopy. In addition, the bonding situation was analyzed with modern charge and energy decomposition analysis.

Emissive β-diketones (bdks) and difluoroboron complexes (BF₂bdks) exhibit multi-stimuli responsive luminescence, including solvatochromism, viscochromism, aggregation induced emission, thermal and mechanochromic luminescence, halochromism and pH sensing. In this study, a series of six-membered heterocycle-substituted (piperidine, morpholine, 1-methyl piperazine) bdk ligands and boron complexes were synthesized, and their luminescent properties were investigated. All the compounds exhibited red-shifted emission in more polar solvents due to intramolecular charge transfer as well as higher emission intensity in more viscous environments. In response to solubility changes in water/tetrahydrofuran mixtures, while the piperazine bdk ligand showed aggregation caused quenching, the piperidine and morpholine bdks displayed enhanced emission upon aggregation. In the solid state, all ligands exhibited mechanochromism. More dramatic halochromism was observed for the piperidine boron dye spin cast film. In solution, for the boron dyes under varying pH values (1–13), different protonated and deprotonated forms were analyzed according to the measured emission spectra.

Covalent probes serve as valuable tools for global investigation of protein function and ligand binding capacity. Despite efforts to expand coverage of residues available for chemical proteomics (e.g., cysteine and lysine), a large fraction of the proteome remains inaccessible with current activity-based probes. Here, we introduce sulfur-triazole exchange (SuTEx) chemistry as a tunable platform for developing covalent probes with broad applications for chemical proteomics. We show modifications to the triazole leaving group can furnish sulfonyl probes with ~5-fold enhanced chemoselectivity for tyrosines over other nucleophilic amino acids to investigate more than 10,000 tyrosine sites in lysates and live cells. We discover that tyrosines with enhanced nucleophilicity are enriched in enzymatic, protein–protein interaction and nucleotide recognition domains. We apply SuTEx as a chemical phosphoproteomics strategy to monitor activation of phosphotyrosine sites. Collectively, we describe SuTEx as a biocompatible chemistry for chemical biology investigations of the human proteome.