Self-assembly of chiroptical ionic co-crystals from silver nanoclusters and organic macrocycles.

Atomically precise nanoclusters can be assembled into ordered superlattices with unique electronic, magnetic, optical and catalytic properties. The co-crystallization of nanoclusters with functional organic molecules provides opportunities to access an even wider range of structures and properties, but can be challenging to control synthetically. Here we introduce a supramolecular approach to direct the assembly of atomically precise silver nanoclusters into a series of nanocluster‒organic ionic co-crystals with tunable structures and properties.

The role of metal accessibility on carbon dioxide electroreduction in atomically precise nanoclusters.

Atomically precise nanoclusters (NCs) can be designed with high faradaic efficiency for the electrochemical reduction of CO to CO (FE) and provide useful model systems for studying the metal-catalysed CO reduction reaction (CORR). While size-dependent trends are commonly evoked, the effect of NC size on catalytic activity is often convoluted by other factors such as changes to surface structure, ligand density, and electronic structure, which makes it challenging to establish rigorous structure-property relationships. Herein, we report a detailed investigation of a series of NCs [AuAg(C[triple bond, length as m-dash]CR)Cl(PPh), AuAg(C[triple bond, length as m-dash]CR)Cl, and Au(C[triple bond, length as m-dash]CR)/AuAg(C[triple bond, length as m-dash]CR)] with similar sizes and core structures but different ligand packing densities to investigate how the number of accessible metal sites impacts CORR activity and selectivity.

A Double Open-Shelled Au Nanocluster with Increased Catalytic Activity and Stability.

Atomically precise metal nanoclusters (NCs) are an intriguing class of crystalline solids with unique physicochemical properties derived from tunable structures and compositions. Most atomically precise NCs require closed-shells and coordinatively saturated surface metals in order to be stable. Herein, we report Au(C≡CBu) and AuAg(C≡CBu), which feature open electronic and geometric shells, leading to both paramagnetism (23 valence e) and enhanced catalytic activity from a single coordinatively unsaturated surface metal.

Lifetime dynamics of plasmons in the few-atom limit.

Polycyclic aromatic hydrocarbon (PAH) molecules are essentially graphene in the subnanometer limit, typically consisting of 50 or fewer atoms. With the addition or removal of a single electron, these molecules can support molecular plasmon (collective) resonances in the visible region of the spectrum. Here, we probe the plasmon dynamics in these quantum systems by measuring the excited-state lifetime of three negatively charged PAH molecules: anthanthrene, benzo[ghi]perylene, and perylene.

Multicolor Electrochromic Devices Based on Molecular Plasmonics.

Polycyclic aromatic hydrocarbon (PAH) molecules, the hydrogen-terminated, sub-nanometer-scale version of graphene, support plasmon resonances with the addition or removal of a single electron. Typically colorless when neutral, they are transformed into vivid optical absorbers in either their positively or negatively charged states. Here, we demonstrate a low-voltage, multistate electrochromic device based on PAH plasmon resonances that can be reversibly switched between nearly colorless (0 V), olive (+4 V), and royal blue (-3.

Molecular Plasmonics.

Graphene supports surface plasmons that have been observed to be both electrically and geometrically tunable in the mid- to far-infrared spectral regions. In particular, it has been demonstrated that graphene plasmons can be tuned across a wide spectral range spanning from the mid-infrared to the terahertz. The identification of a general class of plasmonic excitations in systems containing only a few dozen atoms permits us to extend this versatility into the visible and ultraviolet.