“Click” Chemistry Mildly Stabilizes Bifunctional Gold Nanoparticles for Sensing and Catalysis

A large family of bifunctional 1,2,3‐triazole derivatives that contain both a polyethylene glycol (PEG) chain and another functional fragment (e.g., a polymer, dendron, alcohol, carboxylic acid, allyl, fluorescence dye, redox‐robust metal complex, or a β‐cyclodextrin unit) has been synthesized by facile “click” chemistry and mildly coordinated to nanogold particles, thus providing stable water‐soluble gold nanoparticles (AuNPs) in the size range 3.0–11.2 nm with various properties and applications. In particular, the sensing properties of these AuNPs are illustrated through the detection of an analogue of a warfare agent (i.e., sulfur mustard) by means of a fluorescence “turn‐on” assay, and the catalytic activity of the smallest triazole–AuNPs (core of 3.0 nm) is excellent for the reduction of 4‐nitrophenol in water.     

Elementary Steps of Gold Catalysis: NMR Spectroscopy Reveals the Highly Cationic Character of a “Gold Carbenoid”

What are you? Even though the metal‐induced ring opening of 3,3‐disubstituted cyclopropenes is known to serve as a genuine carbene generator, the use of Au^I in this reaction leads to a reactive intermediate with highly cationic character. This result has important implications for gold catalysis in general, which in the past has been commonly attributed to the intervention of gold carbenes.

     

Gold Nanoparticle–Fluorophore Complexes: Sensitive and Discerning “Noses” for Biosystems Sensing

Gold nanoparticles (NPs) efficiently quench adsorbed fluorophores. Upon disruption of such complexes by an analyte, fluorescence turn‐on is observed. By judicious choice of the functionalized NP and the fluorophore, these complexes display different responses to analytes, thus leading to versatile yet simple array‐based sensor platforms. Using this strategy, we can identify proteins in buffer and serum, distinguish between both different species and different strains of bacteria, and differentiate between healthy, cancerous, and metastatic human and murine cells.     

Hydrogen‐Bond‐Assisted “Gold Cold Fusion” for Fabrication of 2D Web Structures

Keeping their cool : Fabrication of a 2D weblike nanonetwork of gold was successfully demonstrated through a two‐step procedure including complexation of gold precursors to a weblike supramolecular assembly of surfactant followed by in situ reduction of the precursors to gold. Molecular assemblies stabilized by hydrogen bonding provided a sound template, leading to the highly integrated structure of gold through room‐temperature (cold) nanostructure fusion.

     

“Dumbbell”‐ and “Clackers”‐Shaped Dimeric Derivatives of Monocarba‐closo‐dodecaborate

We designed, synthesized, and characterized two types of dimeric forms of monocarba‐closo‐dodecaborate, namely, a “dumbbell”‐shaped dianion having a C?C bond and a “clackers”‐shaped monoanion having an iodonium linker. The unique architectures of these anionic molecules were established by X‐ray analysis. Spectroscopic analysis, DFT calculations, and reactivity experiments revealed high anionic and chemical stability of both anions, which are crucial properties for weakly coordinating anions.