Hydrogenation of Graphene by Reaction at High Pressure and High Temperature.

The chemical reaction between hydrogen and purely sp(2)-bonded graphene to form graphene's purely sp(3)-bonded analogue, graphane, potentially allows the synthesis of a much wider variety of novel two-dimensional materials by opening a pathway to the application of conventional chemistry methods in graphene. Graphene is currently hydrogenated by exposure to atomic hydrogen in a vacuum, but these methods have not yielded a complete conversion of graphene to graphane, even with graphene exposed to hydrogen on both sides of the lattice. By heating graphene in molecular hydrogen under compression to modest high pressure in a diamond anvil cell (2.6-5.0 GPa), we are able to react graphene with hydrogen and propose a method whereby fully hydrogenated graphane may be synthesized for the first time.

Scanning tunnelling microscopy of suspended graphene.

Suspended graphene has been studied by STM for the first time. Atomic resolution on mono- and bi-layer graphene samples has been obtained after ridding the graphene surface of contamination via high-temperature annealing. Static local corrugations (ripples) have been observed on both types of structures.

Self-assembled metallic nanowires on a dielectric support: Pd on rutile TiO2(110).

Palladium nanoparticles supported on rutile TiO(2)(110)-1 x 1 have been studied using the complementary techniques of scanning tunneling microscopy and X-ray photoemission electron microscopy. Two distinct types of palladium nanoparticles are observed, namely long nanowires up to 1000 nm long, and smaller dotlike features with diameters ranging from 80-160 nm. X-ray photoemission electron microscopy reveals that the nanoparticles are composed of metallic palladium, separated by the bare TiO(2)(110) surface.

Molecular routes for spin cluster qubits.

We report on real molecular complexes and propose strategies that explore the possibility of implementation of specific quantum computation architectures with molecular spin systems. We focus on Cr3+ carboxylate derivatives and use the Loss-DiVincenzo scheme as reference.

A family of manganese rods: syntheses, structures, and magnetic properties.

The reaction of the mixed-valent metal triangles [Mn(3)O(O(2)CR)(6)(py)(3)] (R = CH(3), Ph, C(CH(3))(3)) with the tripodal ligands H(3)thme (1,1,1-tris(hydroxymethyl)ethane) and H(3)tmp (1,1,1-tris(hydroxymethyl)propane) in MeCN, produces a family of manganese rodlike complexes whose structures are all derived from a series of edge-sharing triangles. Variable temperature direct current (dc) magnetic susceptibility data were collected for all complexes in the 1.8-300 K temperature range in fields up to 7.0 T. Complex 1, [Mn(12)O(4)(OH)(2)(PhCOO)(12)(thme)(4)(py)(2)], has an S = 7 ground state with the parameters g = 1.98 and D = -0.13 K. Complex 2, [Mn(8)O(4)((CH(3))(3)CCO(2))(10)(thme)(2)(py)(2)] has a ground state of S = 6, with g = 1.81 and D = -0.36 K. Complex 3, [Mn(7)O(2)(PhCO(2))(9)(thme)(2)(py)(3)], has a spin ground states of S = 7 with the parameters g = 1.78 and D = -0.20 K. The best fit for complex 4, [Mn(6)((CH(3))(3)CCO(2))(8)(tmp)(2)(py)(2)], gave a spin ground state of S = 3 with the parameters g = 1.73 and D = -0.75 K, but was of poorer quality than that normally obtained. The presence of multiple Mn(2+) ions in the structure of 4 leads to the presence of low-lying excited states with energy levels very close to the ground state, and in the case of complex 5, [Mn(6)(CH(3)CO(2))(6)(thme)(2)(H(2)tea)(2)], no satisfactory fit of the data was obtained. DFT calculations on 4 and 5 indicate complexes with spin ground states of S = 4 and S = 0 respectively, despite their topological similarities. Single-crystal hysteresis loop and relaxation measurements show complex 1 to be a SMM.

A centred, elongated "ferric tetrahedron" with an S= 15/2 spin ground state.

The reaction of anhydrous FeCl(3) with 1H-benzotriazole-1-methanol (Bta-CH(2)OH) in MeOH produces the pentanuclear complex [Fe(5)O(2)(OMe)(2)(Bta)(4)(BtaH)(MeOH)(5)Cl(5)], containing a distorted tetrahedron of four Fe ions centred on a fifth. The central Fe is antiferromagnetically coupled to the peripheral Fe ions resulting in an S= 15/2 spin ground state.

From local adsorption stresses to chiral surfaces: (R,R)-tartaric acid on Ni(110).

The chiral molecule (R,R)-tartaric acid adsorbed on nickel surfaces creates highly enantioselective heterogeneous catalysts, but the nature of chiral modification remains unknown. Here, we report on the behavior of this chiral molecule with a defined Ni(110) surface. A combination of reflection absorption infrared spectroscopy, scanning tunneling microscopy, and periodic density functional theory calculations reveals a new mode of chiral induction. At room temperatures and low coverages, (R,R)-tartaric acid is adsorbed in its bitartrate form with two-point bonding to the surface via both carboxylate groups. The molecule is preferentially located above the 4-fold hollow site with each carboxylate functionality adsorbed at the short bridge site via O atoms placed above adjacent Ni atoms. However, repulsive interactions between the chiral OH groups of the molecule and the metal atoms lead to severely strained adsorption on the bulk-truncation Ni(110) surface. As a result, the most stable adsorption structure is one in which this adsorption-induced stress is alleviated by significant relaxation of surface metal atoms so that a long distance of 7.47 A between pairs of Ni atoms can be accommodated at the surface. Interestingly, this leads the bonding Ni atoms to describe a chiral footprint at the surface for which all local mirror symmetry planes are destroyed. Calculations show only one chiral footprint to be favored by the (R,R)-tartaric acid, with the mirror adsorption site being unstable by 6 kJ mol(-1). This energy difference is sufficient to enable the same local chiral reconstruction and motif to be sustained over 90% of the system, leading to an overall highly chiral metal surface.