Electrochemical Scanning Tunneling Spectroscopy of Redox-Active Molecules Bound by Au−C Bonds

Ricci, Alejandra Marcela; Calvo, Ernesto J.; Martı́n, Santiago; Nichols, Richard J.

doi:10.1021/ja907867b

Cited by 60 publications

(59 citation statements)

References 34 publications

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“…Our group has contributed with similar studies of Au-C and Au-S short-tethered Os bipyridine-pyridine chloride complex in the STM Btunneling gap^configuration with similar sequential two-step ET mechanism between the molecule and the tip and substrate metal contacts with partial vibration relaxation [23]. The Os[(bpy) 2 (PyCH 2 NH 2 CO-]ClO 4 attached to Au electrodes by self-assembling mercapto alkanoic or mercaptobenzoic acids with post-functionalization via amide formation with primary amines in the metal complex has been reported by Ricci et al [23][24][25][26][27][28].…”

Section: (Os Andmentioning

confidence: 88%

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Electrochemical gating of single osmium molecules tethered to Au surfaces

Herrera

Adam

Ricci

et al. 2015

J Solid State Electrochem

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The electrochemical study of electron transport between Au electrodes and the redox molecule Os[(bpy) 2 (PyCH 2 NH 2 CO-]ClO 4 tethered to molecular linkers of different length (1.3 to 2.9 nm) to Au surfaces has shown an exponential decay of the rate constant k ET 0 with a slope β = 0.53 consistent with through bond tunneling to the redox center. Electrochemical gating of single osmium molecules in an asymmetric tunneling nano-gap between a Au(111) substrate electrode modified with the redox molecules and a Pt-Ir tip of a scanning tunneling microscope was achieved by independent control of the reference electrode potential in the electrolyte, E ref − E s , and the tipsubstrate bias potential, E bias . Enhanced tunneling current at the osmium complex redox potential was observed as compared to the off resonance set point tunneling current with a linear dependence of the overpotential at maximum current vs. the E bias . This corresponds to a sequential two-step electron transfer with partial vibration relaxation from the substrate Au(111) to the redox molecule in the nano-gap and from this redox state to the Pt-Ir tip according to the model of Kuznetsov and Ulstrup (J Phys Chem A 104: 11531, 2000). Comparison of short and long linkers of the osmium complex has shown the same two-step ET (electron transfer) behavior due to the long time scale in the complete reduction-oxidation cycle in the electrochemical tunneling spectroscopy (EC-STS) experiment as compared to the time constants for electron transfer for all linker distances, k ET 0 .

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Section: (Os Andmentioning

confidence: 88%

“…The Os[(bpy) 2 (PyCH 2 NH 2 CO-]ClO 4 attached to Au electrodes by self-assembling mercapto alkanoic or mercaptobenzoic acids with post-functionalization via amide formation with primary amines in the metal complex has been reported by Ricci et al [23][24][25][26][27][28].…”

Section: (Os Andmentioning

confidence: 99%

Electrochemical gating of single osmium molecules tethered to Au surfaces

Herrera

Adam

Ricci

et al. 2015

J Solid State Electrochem

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“…21 Electrochemically gated molecular junctions have also been realized to achieve conductivity modulation of organic and metal complexes. 22,23 For example, with a ferrocene unit terminated with two cysteamine groups, Tao et al showed that with an electrochemical gate set at 0.6 V the current increases by one order of magnitude. This gate effect is ascribed to oxidation of the molecule when its HOMO is raised to the Fermi level of the electrode.…”

Section: Functional Molecular Junctions With Metal Complexesmentioning

confidence: 99%

Metal complexes in molecular junctions

Rigaut

2013

Dalton Trans.

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“…Conductance switching in molecular junctions has been demonstrated previously using various means including light, 1, 2 bias pulses, 3 electrostatic-, 4,5 and electrochemical gating. 6,7 The concept of "electrochemical gating" which provides the opportunity to overcome the technical challenges of incorporating a gate electrode in a solid-state molecular device, has been employed in electrochemically active molecular systems, including viologens, [8][9][10] oligoaniline, 11 ferrocene, [12][13][14] transition metal complexes, 7,15,16 perylenebisimides, [17][18][19] redox-active proteins, 20,21 quinones 22,23 and tetrathiafulvalene, 24 as well as redox-inactive molecules. 25 In the case of redox-inactive molecules, or more generally when the electrode potential does not overlap with the molecule's redox potential, the effect of the gate is simply to shift the molecular levels up or down in energy relative to the Fermi level.…”

mentioning

confidence: 99%

Electrochemical Control of Single-Molecule Conductance by Fermi-Level Tuning and Conjugation Switching

et al. 2014

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Controlling charge transport through a single molecule connected to metallic electrodes remains one of the most fundamental challenges of nanoelectronics. Here we use electrochemical gating to reversibly tune the conductance of two different organic molecules, both containing anthraquinone (AQ) centers, over >1 order of magnitude. For electrode potentials outside the redox-active region, the effect of the gate is simply to shift the molecular energy levels relative to the metal Fermi level. At the redox potential, the conductance changes abruptly as the AQ unit is oxidized/reduced with an accompanying change in the conjugation pattern between linear and cross conjugation. The most significant change in conductance is observed when the electron pathway connecting the two electrodes is via the AQ unit. This is consistent with the expected occurrence of destructive quantum interference in that case. The experimental results are supported by an excellent agreement with ab initio transport calculations.

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Electrochemical Scanning Tunneling Spectroscopy of Redox-Active Molecules Bound by Au−C Bonds

Cited by 60 publications

References 34 publications

Electrochemical gating of single osmium molecules tethered to Au surfaces

Electrochemical gating of single osmium molecules tethered to Au surfaces

Metal complexes in molecular junctions

Electrochemical Control of Single-Molecule Conductance by Fermi-Level Tuning and Conjugation Switching

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