Incorporating Diamondoids as Electrolyte Additive in the Sodium Metal Anode to Mitigate Dendrite Growth.

Owing to the high abundance and gravimetric capacity (1165.78 mAh g ) of pure sodium, it is considered as a promising candidate for the anode of next-generation batteries. However, one major challenge needs to be solved before commercializing the sodium metal anode: The growth of dendrites during metal plating.

Sterically controlled mechanochemistry under hydrostatic pressure.

Mechanical stimuli can modify the energy landscape of chemical reactions and enable reaction pathways, offering a synthetic strategy that complements conventional chemistry. These mechanochemical mechanisms have been studied extensively in one-dimensional polymers under tensile stress using ring-opening and reorganization, polymer unzipping and disulfide reduction as model reactions. In these systems, the pulling force stretches chemical bonds, initiating the reaction.

Monochromatic Photocathodes from Graphene-Stabilized Diamondoids.

The monochromatic photoemission from diamondoid monolayers provides a new strategy to create electron sources with low energy dispersion and enables compact electron guns with high brightness and low beam emittance for aberration-free imaging, lithography, and accelerators. However, these potential applications are hindered by degradation of diamondoid monolayers under photon irradiation and electron bombardment. Here, we report a graphene-protected diamondoid monolayer photocathode with 4-fold enhancement of stability compared to the bare diamondoid counterpart.

Hybrid metal-organic chalcogenide nanowires with electrically conductive inorganic core through diamondoid-directed assembly.

Controlling inorganic structure and dimensionality through structure-directing agents is a versatile approach for new materials synthesis that has been used extensively for metal-organic frameworks and coordination polymers. However, the lack of 'solid' inorganic cores requires charge transport through single-atom chains and/or organic groups, limiting their electronic properties. Here, we report that strongly interacting diamondoid structure-directing agents guide the growth of hybrid metal-organic chalcogenide nanowires with solid inorganic cores having three-atom cross-sections, representing the smallest possible nanowires.

Ultralow effective work function surfaces using diamondoid monolayers.

Electron emission is critical for a host of modern fabrication and analysis applications including mass spectrometry, electron imaging and nanopatterning. Here, we report that monolayers of diamondoids effectively confer dramatically enhanced field emission properties to metal surfaces. We attribute the improved emission to a significant reduction of the work function rather than a geometric enhancement.

Selective preparation of diamondoid phosphonates.

We present an effective sequence for the preparation of phosphonic acid derivatives of the diamondoids diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane. The reactions of the corresponding diamondoid hydroxy derivatives with PCl3 in sulfuric or trifluoroacetic acid give mono- as well as didichlorophosphorylated diamondoids in high preparative yields.

Electronic structure tuning of diamondoids through functionalization.

We investigated the changes in electronic structures induced by chemical functionalization of the five smallest diamondoids using valence photoelectron spectroscopy. Through the variation of three parameters, namely functional group (thiol, hydroxy, and amino), host cluster size (adamantane, diamantane, triamantane, [121]tetramantane, and [1(2,3)4]pentamantane), and functionalization site (apical and medial) we are able to determine to what degree these affect the electronic structures of the overall systems. We show that unlike, for example, in the case of halobenzenes, the ionization potential does not show a linear dependence on the electronegativity of the functional group.

Nanodiamonds in sugar rings: an experimental and theoretical investigation of cyclodextrin-nanodiamond inclusion complexes.

We report on the noncovalent interactions of nanodiamond carboxylic acids derived from adamantane, diamantane, and triamantane with β- and γ-cyclodextrins. The water solubility of the nanodiamonds was increased by attaching an aromatic dicarboxylic acid via peptide coupling. Isothermal titration calorimetry experiments were performed to determine the thermodynamic parameters (K(a), ΔH, ΔG and ΔS) for the host-guest inclusion.

Diamondoid-modified DNA.

We prepared novel C5-modified triphosphates and phosphoramidites with a diamondoid functionally linked to the nucleobase. Using primer extension experiments with different length templates we investigated whether the modified triphosphates were enzymatically incorporated into DNA and whether they were further extended. We found that all three modified nucleotides can be incorporated into DNA using a single-nucleotide incorporation experiment, but only partially using two templates that demand for multiple incorporation of the modified nucleotides.

Experimental and theoretical study of the absorption properties of thiolated diamondoids.

Nanoscale hybrid systems are a new class of molecular aggregates that offer numerous new possibilities in materials design. Diamondoid thiols are promising nanoscale building blocks for such hybrid systems. They allow the incorporation of functional groups and the investigation of their effects on the unique materials' properties of diamondoids.

The influence of a single thiol group on the electronic and optical properties of the smallest diamondoid adamantane.

At the nanoscale, the surface becomes pivotal for the properties of semiconductors due to an increased surface-to-bulk ratio. Surface functionalization is a means to include semiconductor nanocrystals into devices. In this comprehensive experimental study we determine in detail the effect of a single thiol functional group on the electronic and optical properties of the hydrogen-passivated nanodiamond adamantane.

[123]Tetramantane: parent of a new family of sigma-helicenes.

We present a new type of sigma-helical structure based on a diamondoid (nanodiamond) framework, C(2)-symmetric [123]tetramantane, whose (+) and (-) isomers could be enantioseparated by HPLC techniques. Bromination of the enantiopure hydrocarbon led to the isolation of (+)-7-bromo-[123]tetramantane, which could be crystallized and subjected to X-ray structure analysis. Using the anomalous dispersion, we have identified this compound as the P isomer for the hydrocarbon moiety.

Reactivities of the prism-shaped diamondoids [1(2)3]tetramantane and [12312]hexamantane (cyclohexamantane).

Various functional groups have been incorporated into the structures of the naturally occurring diamondoids [1(2)3]tetramantane and [12312]hexamantane (cyclohexamantane), which represent hydrogen-terminated prism-shaped nanodiamonds. The selectivities of the C-H substitutions in [1(2)3]tetramantane depend on the reagent employed and give products substituted at either central (through bromination) or peripheral (through nitroxylation and photo-oxidation) positions. The hydrogen-coupled electron-transfer mechanism of C-H nitroxylation with the model electrophile NO(2)(+).

Origin of the monochromatic photoemission peak in diamondoid monolayers.

Recent photoemission experiments have discovered a highly monochromatized secondary electron peak emitted from diamondoid self-assembled monolayers on metal substrates. New experimental data and simulation results are presented to show that a combination of negative electron affinity and strong electron-phonon scattering is responsible for this behavior. The simulation results are generated using a simple Monte Carlo transport algorithm.

Near-edge X-ray absorption fine structure spectroscopy of diamondoid thiol monolayers on gold.

Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications.

Reactivity of [1(2,3)4]pentamantane (Td-pentamantane): a nanoscale model of diamond.

To model the chemical properties of the hydrogen-terminated nanodiamond {111} and {110} surfaces, the functionalizations of the higher diamondoid [1(2,3)4]pentamantane were studied. [1(2,3)4]Pentamantane reacts selectively with neat bromine to give the medial 2-mono- and 2,4-disubstitution products. In contrast, oxidation with nitric acid as well as single-electron-transfer oxidation involving the [1(2,3)4]pentamantane radical cation results in apical C7-substitutions.

Functionalized nanodiamonds: triamantane and [121]tetramantane.

The selective functionalizations of the fundamental hydrogen-terminated nanodiamonds triamantane 1, as well as the most symmetrical representative of the tetramantanes (C(2h)-[121]tetramantane 2) were elaborated. Electrophilic reagents (Br2, HNO3) predominantly attack the medial C-H positions of the cages; bromination of 2 gave the medial 2-bromo derivative almost exclusively. Highly selective apical substitution in 1 and 2 is possible either under single-electron-transfer oxidations via hydrocarbon radical cations or through photoacetylation with diacetyl.

Functionalized nanodiamonds part 3: thiolation of tertiary/bridgehead alcohols.

[reaction: see text] Treatment of acyclic as well as polycyclic tertiary mono- and dihydroxy hydrocarbon derivatives with thiourea in the presence of hydrobromic and acetic acid represents a convenient one-step route to the respective tertiary thiols and dithiols. This procedure was used for the preparation of diamondoid thiols of diamantane, triamantane, [121]tetramantane, and others that are prospective nanoelectronic materials.

Functionalized nanodiamonds part I. An experimental assessment of diamantane and computational predictions for higher diamondoids.

The structures, strain energies, and enthalpies of formation of diamantane 1, triamantane 2, isomeric tetramantanes 3-5, T(d)-pentamantane 6, and D(3d)-hexamantane 7, and the structures of their respective radicals, cations, as well as radical cations, were computed at the B3LYP/6-31G* level of theory. For the most symmetrical hydrocarbons, the relative strain (per carbon atom) decreases from the lower to the higher diamondoids. The relative stabilities of isomeric diamondoidyl radicals vary only within small limits, while the stabilities of the diamondoidyl cations increase with cage size and depend strongly on the geometric position of the charge.