Close-packed planar arrays of nanometer-diameter metal clusters that are covalently linked to each other by rigid, double-ended organic molecules have been self-assembled. Gold nanocrystals, encapsulated a monolayer alkyl thiol molecules, were cast from colloidal solution onto flat substrate form close-packed cluster monolayer. Organic interconnects (aryl dithiols or aryl di-isonitriles) displaced the and adjacent in two-dimensional superlattice quantum dots coupled uniform tunnel junctions....

The recent literature on photochemical and photoelectrochemical reductions of CO 2 is reviewed. different methods achieving light absorption, electron-hole separation, electrochemical reduction are considered. Energy gap matching for to products, including CO, formic acid, methanol, used identify the most promising systems. Different approaches lowering overpotentials high chemical selectivities by employing catalysts described compared.

Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was image these nanostructures measure their current-voltage characteristics as function of the separation between probe tip metal cluster. At room temperature, when positioned over bonded XYL SAM, data showed...

This paper presents a comparison of the theoretical and experimental current-voltage (I-V) characteristics self-assembled monolayer $\ensuremath{\alpha},{\ensuremath{\alpha}}^{\ensuremath{'}}\ensuremath{-}\mathrm{x}\mathrm{y}\mathrm{l}\mathrm{y}\mathrm{l}$ dithiol molecules on gold substrate measured with scanning tunneling microscope probe. Good quantitative agreement is obtained tip-molecule distance as only ``fitting parameter.'' Several other thiol-coupled that we have studied also show...

Realization of heterogeneous electrochemical CO2-to-fuel conversion via molecular catalysis under high-flux conditions requires the assembly large quantities reactant-accessible catalysts on conductive surfaces. As a proof principle, we demonstrate that electrophoretic deposition thin films an appropriately chosen metal–organic framework (MOF) material is effective method for immobilizing needed quantity catalyst. For electrocatalytic CO2 reduction, used contains functionalized Fe-porphyrins...

A relatively simple and straightforward procedure for characterizing molecular wires is to measure the conductance spectrum by forming a self-assembled ordered monolayer (SAM) on metallic surface using high scanning-tunneling microscope resolution (STM) tip as other contact. We find that (dI/dV vs. V) can be understood fairly well in terms of model, provided spatial profile electrostatic potential under bias properly accounted for. The effect particularly striking convert symmetric conductor...

Five Re(bipy)(CO)3Cl complexes were prepared and studied where bipy was 4,4′-dicarboxyl-2,2′-bipyridine (1), 2,2′-bipyridine (2), 4,4′-dimethyl-2,2′-bipyridine (3), 4,4′-di-tert-butyl-2,2′-bipyridine (4), 4,4′-dimethoxy-2,2′-bipyridine (5). From this group, a significantly improved catalyst, Re(bipy-tBu)(CO)3Cl for the reduction of carbon dioxide to monoxide found. The complex shows two one-electron reductions under argon, one reversible at −1445 mV (vs SCE), irreversible −1830 mV. Under CO2...

In this paper, we present a method for computing the resistance of molecular wires and illustrate it with systematic theoretical study particular class organic molecules. These molecules consist one or more benzene rings thiol(-SH) group at ends. This end can attach readily to metallic surfaces, thus allowing molecule function as nanoelectronic interconnect. The conduction through these low bias occurs by tunneling, leading resistances that are typically several tens megaohms. goes up...

With the goal of improving previously reported Mn bipyridine electrocatalysts in terms increased activity and reduced overpotential, a bulky ligand, 6,6'-dimesityl-2,2'-bipyridine (mesbpy), was utilized to eliminate dimerization catalytic cycle. Synthesis, electrocatalytic properties, X-ray diffraction (XRD) studies, infrared spectroelectrochemistry (IR-SEC) Mn(mesbpy)(CO)3Br [Mn(mesbpy)(CO)3(MeCN)](OTf) are reported. Unlike catalysts, these complexes exhibit single, two-electron reduction...

Electrocatalytic properties, X-ray crystallographic studies, and infrared spectroelectrochemistry (IR-SEC) of Mn(bpy-tBu)(CO)3Br [Mn(bpy-tBu)(CO)3(MeCN)](OTf) are reported. Addition Brönsted acids to CO2-saturated solutions these Mn complexes subsequent reduction the lead stable efficient production CO from CO2. Unlike analogous Re catalysts, catalysts require addition for catalytic turnover. Current densities up 30 mA/cm2 were observed during bulk electrolysis using 5 mM Mn(bpy-tBu)(CO)3Br,...

A manganese bipyridine complex, Mn(bpydc)(CO)3Br (bpydc = 5,5′-dicarboxylate-2,2′-bipyridine), has been incorporated into a highly robust Zr(IV)-based metal–organic framework (MOF) for use as CO2 reduction photocatalyst. In conjunction with [Ru(dmb)3]2+ (dmb 4,4′-dimethyl-2,2′-bipyridine) photosensitizer and 1-benzyl-1,4-dihydronicotinamide (BNAH) sacrificial reductant, Mn-incorporated MOFs efficiently catalyze to formate in DMF/triethanolamine under visible-light irradiation. The...

[Re(bpy)(CO)3]− is a well-established homogeneous electrocatalyst for the reduction of CO2 to CO. Recently, substitution more abundant transition metal Mn Re yielded similarly active electrocatalyst, [Mn(bpy)(CO)3]−. Compared catalyst, this catalyst operates at lower applied potential but requires presence weak acid in solution catalytic activity. In study, we employ quantum chemistry combined with continuum solvation and microkinetics examine mechanism by each catalyst. We use cyclic...

The homogeneous CO(2) reduction activity of several nickel cyclam complexes was examined by cyclic voltammetry and controlled potential electrolysis. CO production with high efficiency from unsubstituted Ni(cyclam) verified, while the found to be attenuated methyl substitution amines on ring. Reactivity also probed using density functional theory (DFT) calculations. relative binding energies Ni(I) state obtained DFT were match well experimental results shed light possible importance isomeric...

Earth-abundant manganese bipyridine (bpy) complexes are well-established molecular electrocatalysts for proton-coupled carbon dioxide (CO2) reduction to monoxide (CO). Recently, a bulky ligand, 6,6'-dimesityl-2,2'-bipyridine (mesbpy), was utilized significantly lower the potential necessary access doubly reduced states of these catalysts by eliminating their ability dimerize after one-electron reduction. Although this Mn mesbpy catalyst binds CO2 at very low potentials, resulting Mn(I)-COOH...

A complete mechanism for the proton-dependent electrocatalytic reduction of CO2 to CO by fac-Re(bpy)(CO)3Cl that is consistent with experimental observations has been developed using first principles quantum chemistry. Calculated one-electron potentials, nonaqueous pKa's, reaction free energies, and barrier heights provide deep insight into complex as well origin selectivity this catalyst. Protonation then a metastable Re-CO2 intermediate anion precedes Brønsted-acid-catalyzed C-O cleavage...

The homogeneous electrochemical reduction of CO2 by the molecular catalyst [Ni(cyclam)](2+) is studied electrochemistry and infrared spectroelectrochemistry. kinetics are probed varying substrate proton concentrations. Products observed in spectra obtained from spectroelectrochemical experiments. two major species a Ni(I) carbonyl, [Ni(cyclam)(CO)](+), Ni(II) coordinated bicarbonate, [Ni(cyclam)(CO2OH)](+). rate-limiting step during electrocatalysis determined to be CO loss deactivated...

The hydricity ΔG°H– of a metal hydride is an important parameter for describing the reactivity such complexes. Here, we compile comprehensive data set consisting 51 transition-metal complexes [M-H](n−1)+ with known values in acetonitrile which one-electron reduction parent complex [M]n+ reversible. Plotting as function respective E1/2(Mn+/(n–1)+) yields robust linear correlation. While this correlation has been previously noted limited sets, our analysis demonstrates that trend extends over...

The use of infrared spectroelectrochemistry (IR-SEC) as a characterization method for molecular electrocatalysts allows researchers to identify key intermediates and products during the course an electrochemical reaction. Since such reactions are driven by application potential, properly designed cells allow examination stepwise formation active species their subsequent reactivity with substrate. These results can be compared independently verified concomitant generation similar chemical...

In order to help develop robust and deployable molecular electrocatalysts for the reduction of CO2 CO, we must understand effects tuning their structure catalytic conditions. To this end, quantify how modifications catalyst fac-Re(4,4′-R-bpy)(CO)3X (bpy = 2,2′-bipyridine, R OCH3, CH3, tBu, H, CN, CF3; X Cl, Br, py(OTf), or CH3CN(OTf)) with without an added proton source (phenol, acetic acid, 2,2,2-trifluoroethanol) affect stability, activity, overpotential. Through cyclic voltammetry...

In the interpretation of scanning-tunneling spectroscopy data on molecular nanostructures tunneling conductance is often assumed to be proportional local density states molecule. This precludes possibility observing negative differential resistance (NDR). We report here observation NDR in current-voltage $(I\ensuremath{-}V)$ characteristics a self-assembled monolayer $4\ensuremath{-}p\ensuremath{-}\mathrm{terphenylthiol}$ molecules Au(111) surface measured using platinum tip. argue that...

Intramolecular electron transfers within the mixed valence states of ligand bridged hexaruthenium clusters Ru3(μ3-O)(μ-CH3CO2)6(CO)(L)(μ-L')Ru3(μ3-O)(μ-CH3CO2)6(CO)(L) (L' = 1,4-pyrazine; L 4-dimethylaminopyridine (1), pyridine (2), 4-cyanopyridine (3), or L' 4,4'-bipyridine; (4), (5), (6)) were examined. Two discrete and reversible single reductions are evident by cyclic voltammetry in redox chemistry 1−5, intercluster charge-transfer complexes well-defined. The splitting reduction waves,...

Single-electron reductions of linked triruthenium clusters the general type Ru 3 -pyrazine-Ru produced mixed valence systems showing spectroscopic characteristics rapid intramolecular electron transfer. Reflectance infrared spectroelectrochemistry was used to characterize vibrational spectra that contained one carbon monoxide ligand on each cluster. Infrared in CO stretching region showed two resolved, partially coalesced, and coalesced ν(CO) bands for with rate constants transfer k e...

The effective design of an artificial photosynthetic system entails the optimization several important interactions. Herein we report stopped-flow UV-visible (UV-vis) spectroscopy, X-ray crystallographic, density functional theory (DFT), and electrochemical kinetic studies Re(bipy- t Bu)(CO) 3 (L) catalyst for reduction CO 2 to CO. A remarkable selectivity over H + was observed by UV-vis spectroscopy [Re(bipy- ] -1 . reaction with is about 25 times faster than water or methanol at same...