The majority of biomolecules are intrinsically atomically precise, an important characteristic that enables rational engineering of their recognition and binding properties. However, imparting similar precision to hybrid nanoparticles has been challenging due to inherent limitations of the existing chemical methods and availability of properly designed functional building blocks. Here we report a new approach to form atomically precise and highly tunable hybrid nanomolecules with well-defined three-dimensionality. Perfunctionalization of atomically precise clusters with pentafluoroaryl-terminated linkers produces size-tunable rigid cluster nanomolecules. These species are amenable to facile modification with a variety of thiol-containing molecules and macromolecules. Assembly proceeds at room temperature within hours under mild conditions, and the resulting nanomolecules exhibit high stabilities due to their full covalency. We further demonstrate how these nanomolecules grafted with saccharides can exhibit dramatically improved binding affinity toward a protein. Ultimately, the developed strategy allows the rapid generation of precise molecular assemblies for investigating multivalent interactions.

Carboranes are boron-rich molecules that can be functionalized through metal-catalyzed cross-coupling. Here, for the first time, we report the use of bromo-carboranes in palladium-catalyzed cross-coupling for efficient B-N, B-O, and unprecedented B-CN bond formation. In many cases bromo-carboranes outperform the traditionally utilized iodo-carborane species. This marked difference in reactivity is leveraged to circumvent multistep functionalization by directly coupling small nucleophiles (-OH, -NH2, and -CN) and multiple functional groups onto the boron-rich clusters.

We report the development of a new class of phosphorescent zwitterionic bis(heteroleptic) Ir(III) compounds containing pyridyl ligands with weakly coordinating nido-carboranyl substituents. Treatment of phenylpyridine-based Ir(III) precursors with C-substituted ortho-carboranylpyridines in 2-ethoxyethanol results in a facile carborane deboronation and the formation of robust and highly luminescent metal complexes. The resulting nido-carboranyl fragments associate with the cationic Ir(III) center through primarily electrostatic interactions. These compounds phosphoresce at blue wavelengths (450-470 nm) both in a poly(methyl methacrylate) (PMMA) matrix and in solution at 77 K. These complexes display structural stability at temperatures beyond 300 °C and quantum yields greater than 40%. Importantly, the observed quantum yields correspond to a dramatic 10-fold enhancement over the previously reported Ir(III) congeners featuring carboranyl-containing ligands in which the boron cluster is covalently attached to the metal. Ultimately, this work suggests that the use of a ligand framework containing a weakly coordinating anionic component can provide a new avenue for designing efficient Ir(III)-based phosphorescent emitters.

For investigation of structure-property relationships in copper phosphine halide complexes, treatment of copper(I) halides with chiral bis(phosphines) gave dinuclear [Cu((R,R)-i-Pr-DuPhos)(μ-X)] [X = I (1), Br (2), Cl (3)], [Cu(μ-((R,R)-Me-FerroLANE)(μ-I)] (5), and [Cu((S,S)-Et-FerroTANE)(I)] (6), pentanuclear cluster CuI((S,S)-Et-FerroTANE) (7), and the monomeric Josiphos complexes Cu((R,S)-CyPF-t-Bu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9); 1-3, 5, and 7-9 were structurally characterized by X-ray crystallography. Treatment of iodide 1 with AgF gave [Cu((R,R)-i-Pr-DuPhos)(μ-F)] (4). DuPhos complexes 1-4 emitted yellow-green light upon UV irradiation at room temperature in the solid state. This process was studied by low-temperature emission spectroscopy and density functional theory (DFT) calculations, which assigned the luminescence to (M + X)LCT (CuX to DuPhos aryl) excited states. Including Grimme's dispersion corrections in the DFT calculations (B3LYP-D3) gave significantly shorter Cu-Cu distances than those obtained using B3LYP, with the nondispersion-corrected calculations better matching the crystallographic data; other intramolecular metrics are better reproduced using B3LYP-D3. A discussion of the factors leading to this unusual observation is presented.

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A nonfunctionalized bis­(imidazole) ligand precursor has been directly metalated using IrCp*­(OAc)2, leading to a mixture of bis­(protic N-heterocyclic carbene) (bisPNHC) complexes (2a,b). Treatment of 2a,b with HCl gas in CH2Cl2 gave a bisPNHC complex (3a), which has been transformed into a hydride bisPNHC complex. Complex 3a underwent ligand and counterion exchange reactions to afford acetonitrile and ethylamine bisPNHC complexes (5 and 6). Furthermore, these bisPNHC complexes have been tested as catalysts in transfer hydrogenation reactions of ketones and unsaturated ketones.

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