Influence of defects on the electrical characteristics of mercury-drop junctions: self-assembled monolayers of n-alkanethiolates on rough and smooth silver.

This paper compares the structural and electrical characteristics of self-assembled monolayers (SAMs) of n-alkanethiolates, SCn (n = 10, 12, 14), on two types of silver substrates: one used as-deposited (AS-DEP) by an electron-beam evaporator, and one prepared using the method of template-stripping. Atomic force microscopy showed that the template-stripped (TS) silver surfaces were smoother and had larger grains than the AS-DEP surfaces, and reflectance-absorbance infrared spectroscopy showed that SAMs formed on TS substrates were more crystalline than SAMs formed on AS-DEP substrates. The range of current densities, J (A/cm2), measured through mercury-drop junctions incorporating a given SAM on AS-DEP silver was, on average, several orders of magnitude larger than the range of J measured through the same SAM on TS silver, and the AS-DEP junctions failed, on average, 3.

Gating current flowing through molecules in metal-molecules-metal junctions.

We have assembled two junctions that incorporate redox sites between Hg electrodes by different interactions. In the first junction, Hg-SAM-R//R-SAM-Hg, the redox site (R) are covalently linked to each electrode in self assembled monolayers (SAM-R). In the second junction, Hg-SAM//R//SAM-Hg, the redox sites dissolved in solution are trapped by electrostatic interaction at the SAM formed at the electrodes.

Ground- and excited-state electronic structure of an emissive pyrazine-bridged ruthenium(II) dinuclear complex.

The synthesis, characterization, and electrochemical, photophysical, and photochemical properties of the binuclear compounds [(Ru(H8-bpy)2)2((Metr)2Pz)](PF6)2 (1) and [(Ru(D8-bpy)2)2((Metr)2Pz)](PF6)2 (2), where bpy is 2,2'-bipyridine and H2(Metr)2Pz is the planar ligand 2,5-bis(5'-methyl-4'H-[1,2,4]triaz-3'-yl)pyrazine, are reported. Electrochemical and spectro-electrochemical investigations indicate that the ground-state interaction between each metal center is predominantly electrostatic and in the mixed-valence form only a low level of ground-state delocalization is present. Resonance Raman, transient, and time-resolved spectroscopies enable a detailed assignment to be made of the excited-state photophysical properties of the complexes.

Synthesis and characterisation of ruthenium complexes containing a pendent catechol ring.

A series of [Ru(bipy)2L]+ and [Ru(phen)2L]+ complexes where L is 2-[5-(3,4-dimethoxyphenyl)-4H-1,2,4-triazol-3-yl]pyridine (HL1) and 4-(5-pyridin-2-yl-4H-1,2,4-triazol-3-yl)benzene-1,2-diol (HL2) are reported. The compounds obtained have been characterised using X-ray crystallography, NMR, UV/Vis and emission spectroscopies. Partial deuteriation is used to determine the nature of the emitting state and to simplify the NMR spectra.

Complexed nitrogen heterosuperbenzene: the coordinating properties of a remarkable ligand.

Tetra-peri-(tert-butyl-benzo)-di-peri-(pyrimidino)-coronene 1, the parent compound of the nitrogen heterosuperbenzene family N-HSB, is employed as a novel monotopic ligand in the formation of [Pd(eta3-C3H5)(1)]PF6 2 and [Ru(bpy)2(1)](PF6)2 (where bpy = 2,2'-bipyridine 3a and d8-2,2'-bipyridine 3b). These N-coordinated complexes are fully characterized by 1H NMR and IR spectroscopy and ESI-MS. Metal coordination has a profound effect on both the absorption and the emission properties of 1.

Enhancement of luminescence lifetimes of mononuclear ruthenium(II)-terpyridine complexes by manipulation of the sigma-donor strength of ligands.

The synthesis and characterization of mixed ligand 2,2';6',2' '-terpyridine (tpy) ruthenium complexes with 2,6-bis([1,2,4]triazol-3-yl)pyridine, 2,6-bis(5-phenyl-[1,2,4]triazol-3-yl)pyridine, and 2,6-bis([1,2,3,4]tetrazol-5-yl)pyridine are reported. The species are characterized by HPLC, 1H NMR, UV/vis, and emission spectroscopy. The photophysical properties of the complexes are investigated as a function of temperature over the range 80-320 K.