Ultrafast Au(III)-Mediated Arylation of Cysteine.

Through mechanistic work and rational design, we have developed the fastest organometallic abiotic Cys bioconjugation. As a result, the developed organometallic Au(III) bioconjugation reagents enable selective labeling of Cys moieties down to picomolar concentrations and allow for the rapid construction of complex heterostructures from peptides, proteins, and oligonucleotides. This work showcases how organometallic chemistry can be interfaced with biomolecules and lead to a range of reactivities that are largely unmatched by classical organic chemistry tools.

Carrier density and delocalization signatures in doped carbon nanotubes from quantitative magnetic resonance.

High-performance semiconductor materials and devices are needed to supply the growing energy and computing demand. Organic semiconductors (OSCs) are attractive options for opto-electronic devices, due to their low cost, extensive tunability, easy fabrication, and flexibility. Semiconducting single-walled carbon nanotubes (s-SWCNTs) have been extensively studied due to their high carrier mobility, stability and opto-electronic tunability.

Organometallic -arylation Reagents for Rapid PEGylation of Biomolecules.

Bioconjugation techniques for biomolecule-polymer conjugation are numerous; however, slow kinetics and steric challenges generally necessitate excess reagents or long reaction times. Organometallic transformations are known to circumvent these issues; yet, harsh reaction conditions, incompatibility in aqueous media, and substrate promiscuity often limit their use in a biological context. The work reported herein demonstrates a facile and benign organometallic Au(III) -arylation approach that enables the synthesis of poly(ethylene glycol) monomethyl ether (mPEG)-protein conjugates with high efficiency.

An Organometallic Gold(III) Reagent for F Labeling of Unprotected Peptides and Sugars in Aqueous Media.

The F labeling of unprotected peptides and sugars with a Au(III)-[F]fluoroaryl complex is reported. The chemoselective method generates F-labeled -aryl bioconjugates in an aqueous environment in 15 min with high radiochemical yields and displays excellent functional group tolerance. This approach utilizes an air and moisture stable, robust organometallic Au(III) complex and highlights the versatility of designer organometallic reagents as efficient agents for rapid radiolabeling.

Superatomic solid solutions.

In atomic solids, substitutional doping of atoms into the lattice of a material to form solid solutions is one of the most powerful approaches to modulating its properties and has led to the discovery of various metal alloys and semiconductors. Herein we have prepared solid solutions in hierarchical solids that are built from atomically precise clusters. Two geometrically similar metal chalcogenide clusters, CoSe(PEt) and CrTe(PEt), were combined as random substitutional mixture, in three different ratios, in a crystal lattice together with fullerenes.

Cyclopropenylidenes as Strong Carbene Anchoring Groups on Au Surfaces.

The creation of stable molecular monolayers on metallic surfaces is a fundamental challenge of surface chemistry. N-Heterocyclic carbenes (NHCs) were recently shown to form self-assembled monolayers that are significantly more stable than the traditional thiols on Au system. Here we theoretically and experimentally demonstrate that the smallest cyclic carbene, cyclopropenylidene, binds even more strongly than NHCs to Au surfaces without altering the surface structure.

Gold-Carbon Contacts from Oxidative Addition of Aryl Iodides.

Aryl halides are ubiquitous functional groups in organic chemistry, yet despite their obvious appeal as surface-binding linkers and as precursors for controlled graphene nanoribbon synthesis, they have seldom been used as such in molecular electronics. The confusion regarding the bonding of aryl iodides to Au electrodes is a case in point, with ambiguous reports of both dative Au-I and covalent Au-C contacts. Here we form single-molecule junctions with a series of oligophenylene molecular wires terminated asymmetrically with iodine and thiomethyl to show that the dative Au-I contact has a lower conductance than the covalent Au-C interaction, which we propose occurs via an oxidative addition reaction at the Au surface.

Nickel Phosphinidene Molecular Clusters from Organocyclophosphine Precursors.

We report a new family of nickel phosphinidene molecular clusters synthesized from the reaction of bis(1,5-cyclooctadiene)nickel(0) ([Ni(cod) ]) with organocyclophosphine and trialkylphosphine. We found that [Ni(cod) ] cleaves the organocyclophosphine P-P bonds to generate phosphinidene groups, establishing the cyclic molecules as valuable precursors for making charge-neutral molecular clusters passivated by two-electron donor capping ligands. The formation of the cluster core structure is controlled by the bulkiness of the precursor and of the capping ligand.

Determination of the structure and geometry of N-heterocyclic carbenes on Au(111) using high-resolution spectroscopy.

N-heterocyclic carbenes (NHCs) bind very strongly to transition metals due to their unique electronic structure featuring a divalent carbon atom with a lone pair in a highly directional sp-hybridized orbital. As such, they can be assembled into monolayers on metal surfaces that have enhanced stability compared to their thiol-based counterparts. The utility of NHCs to form such robust self-assembled monolayers (SAMs) was only recently recognized and many fundamental questions remain.

In Situ Formation of N-Heterocyclic Carbene-Bound Single-Molecule Junctions.

Self-assembled monolayers (SAMs) formed using N-heterocyclic carbenes (NHCs) have recently emerged as thermally and chemically ultrastable alternatives to those formed from thiols. The rich chemistry and strong σ-donating ability of NHCs offer unique prospects for applications in nanoelectronics, sensing, and electrochemistry. Although stable in SAMs, free carbenes are notoriously reactive, making their electronic characterization challenging.

Phonon Speed, Not Scattering, Differentiates Thermal Transport in Lead Halide Perovskites.

Thermal management plays a critical role in the design of solid state materials for energy conversion. Lead halide perovskites have emerged as promising candidates for photovoltaic, thermoelectric, and optoelectronic applications, but their thermal properties are still poorly understood. Here, we report on the thermal conductivity, elastic modulus, and sound speed of a series of lead halide perovskites MAPbX (X = Cl, Br, I), CsPbBr, and FAPbBr (MA = methylammonium, FA = formamidinium).

Stepwise ligand exchange for the preparation of a family of mesoporous MOFs.

A stepwise ligand exchange strategy is utilized to prepare a series of isoreticular bio-MOF-100 analogues. Specifically, in situ ligand exchange with progressively longer dicarboxylate linkers is performed on single crystalline starting materials to synthesize products with progressively larger mesoporous cavities. The new members of this series of materials, bio-MOFs 101-103, each exhibit permanent mesoporosity and pore sizes ranging from ~2.