In-Situ Infrared Spectroscopic and Scanning Tunneling Microscopy Investigations of the Chemisorption Phases of Uracil, Thymine, and 3-Methyl Uracil on Au(111) Electrodes

Li, Wu-Hu; Haiss, Wolfgang; Floate, Simon; Nichols, Richard J.

doi:10.1021/la9815594

“…8c) and EPW/C 15 FDA show one sharp spike-like wave at more negative potentials as well as a pair of redox peaks due to the one-electron redox reaction of the ferrocene group. Sharp spikelike peaks in CVs similar to those presented above have recently been reported for the adsorption of 2,2 0 -bipyridine, [89][90][91] uracil, [92][93][94] thymine [95] and uridine [96] on single-crystal gold electrode surfaces, and discussed in view of the formation of a 2D condensed phase of organic molecules and its associated phase transition. This result was confirmed by extensive STM experiments.…”

Section: Electrochemistrysupporting

confidence: 78%

Organized Nanostructured Complexes of Polyoxometalates and Surfactants that Exhibit Photoluminescence and Electrochromism

Zhang

¹

,

Liu

²

,

Kurth

³

et al. 2009

Adv Funct Materials

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A variety of functional nanostructured organic/inorganic hybrid materials from the europium‐exchanged derivative of a Preyssler‐type polyoxometalate (POM), [EuP5W30O110]12−, and functional organic surfactants were prepared by the ionic self‐assembly (ISA) route. The effect of organic surfactants on the structure, photoluminescent, electrochemical and electrochromic properties of the POM anions was investigated in detail. All obtained hybrid materials are amphotropic, i.e., exhibit both thermotropic and lyotropic liquid‐crystalline phase behaviour. Investigations of their photophysical properties have shown that the interactions of the various surfactants with the polyanions influence the coordination environments and site symmetry of Eu3+ in different ways. The functional groups in the organic surfactants significantly influence the electrochromic properties and photoluminescence of POMs. Different from normal and pyridine‐containing complexes, no photoluminescence and no electrochromism were observed from the ferrocene‐containing complexes. This may be explained in view of charge transfer between the POM anion and the ferrocenyl group.

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“…The electron tunneling increase is capable of electrically pinpointing each nucleobase. STM observations of nucleobases (28)(29)(30) and DNA oligomers (31-33) had been reported, but those studies failed to identify the chemical species of nucleobases because of the poor chemical selectivity of the STM images. The present approach made it possible to pinpoint particular nucleobases.…”

Section: Resultsmentioning

confidence: 99%

Complementary base-pair-facilitated electron tunneling for electrically pinpointing complementary nucleobases

Ohshiro

¹

,

Umezawa

²

2005

Proc. Natl. Acad. Sci. U.S.A.

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Molecular tips in scanning tunneling microscopy can directly detect intermolecular electron tunneling between sample and tip molecules and reveal the tunneling facilitation through chemical interactions that provide overlap of respective electronic wave functions, that is, hydrogen-bond, metal-coordination-bond, and charge-transfer interactions. Nucleobase molecular tips were prepared by chemical modification of underlying metal tips with thiol derivatives of adenine, guanine, cytosine, and uracil and the outmost single nucleobase adsorbate probes intermolecular electron tunneling to or from a sample nucleobase molecule. We found that the electron tunneling between a sample nucleobase and its complementary nucleobase molecular tip was much facilitated compared with its noncomplementary counterpart. The complementary nucleobase tip was thereby capable of electrically pinpointing each nucleobase. Chemically selective imaging using molecular tips may be coined ''intermolecular tunneling microscopy'' as its principle goes and is of general significance for novel molecular imaging of chemical identities at the membrane and solid surfaces.DNA ͉ nanobioscience ͉ scanning tunneling microscopy E lectron transfer through DNA double strands has attracted much interest (1-4) since Barton and colleagues (5) reported it in the 1990s. The processes of DNA-mediated electron transfer have been explored by spectroscopic methods for detecting photo-induced electron transfer through the DNA strands that are labeled with redox-active probes through intercalation and͞or covalent linkages (6, 7). These experiments have revealed that a DNA strand is capable of mediating electron transfer through the DNA base stacking in the strand (intrastrand pathway) (8-13). On the other hand, the contribution of the electron transfer through the complementary base pair (interstrand pathway) to the overall electron transfer in DNA has been investigated by several researchers (14,15). Here, we report on electron tunneling through the complementary base pair with nucleobase molecular tips for selectively discriminating each of the complementary nucleobases from the other nucleobases (Fig. 1a). The molecular tips are prepared by chemical modification of underlying metal tips typically with self-assembled monolayers (SAMs) of thiols and the outermost single adsorbate probes electron tunneling to or from a sample molecule. Importantly, the tunneling current increases when sample and tip molecules form chemical interactions that provide overlap of their electron wave functions, that is, hydrogen-bond interactions (16-22), metal-coordination-bond interactions (20), and charge-transfer interactions (23). We have thus far demonstrated that this phenomenon can be used for selective observation of chemical species to overcome poor chemical selectivity in conventional scanning tunneling microscopy (STM). We herein found that the electron tunneling between a sample nucleobase and its complementary nucleobase tip was much facilitated compared with its noncomplemen...

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“…New experimental and theoretical perspectives became available when single-crystal electrodes were employed as substrate materials. This step offers the advantage to combine classical electrochemical experiments with the power of structure sensitive in situ techniques, such as scanning probe microscopies (STM, AFM) [23,452,453], vibrational spectroscopies (IRAS [454], SEIRAS [28], SFG [30],. .…”

Section: General Aspectsmentioning

confidence: 99%

“…The phenomenological kinetics of film formation and dissolution, as monitored by i-t, q M -t, or C -t transients after single or multiple potential step protocols, have been described by models that involve (hole) nucleation and growth mechanism [183,219,221,466]. The results of these ''macroscopic'' electrochemical experiments are still scarcely complemented by structural studies, such as IR-or Raman Spectroscopies or the use of UHV techniques after emersion of the electrode [454,463,[472][473][474][475][476]. Remarkable progress in developing a ''true'' atomistic/molecular picture of potentialinduced 2D organic phase formation on adsorbate-modified single-crystal electrodes was achieved by the application of in situ STM and AFM.…”

Section: General Aspectsmentioning

confidence: 99%

Phase Transitions in Two‐dimensional Adlayers at Electrode Surfaces: Thermodynamics, Kinetics, and Structural Aspects

Wandlowski¹

2002

Encyclopedia of Electrochemistry

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The sections in this article are Introduction Thermodynamic Aspects Phase Transitions and Order Parameter Adsorption Isotherms and Lateral Interactions Kinetics of 2 D Phase Formation and Dissolution Diffusion, Adsorption, Autocatalysis Nucleation and Growth Mechanisms Nucleation Growth Coupling of Nucleation and Growth Dissolution of 2 D Condensed Monolayers Examples Phase Transitions in Anionic Adlayers Introduction Phase Formation in Halide Adlayers Phase Transitions in Adlayers of Oxoanions Phase Transitions in UPD —Adlayers Introduction Underpotential Deposition of Copper Ions on Au ( hkl ) Underpotential Deposition of Copper Ions on Pt ( hkl ) Underpotential Deposition of Lead on Ag ( hkl ) Phase Transitions in Organic Monolayers General Aspects Thermodynamic Aspects Kinetic Aspects Case Study I—Coumarin at the Mercury–Aqueous Electrolyte Interface Case Study III —2,2 ′ ‐Bipyridine (2,2 ′ ‐ BP ) on Au ( hkl ) Conclusion and Outlook Acknowledgment

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In-Situ Infrared Spectroscopic and Scanning Tunneling Microscopy Investigations of the Chemisorption Phases of Uracil, Thymine, and 3-Methyl Uracil on Au(111) Electrodes

Cited by 74 publications

References 42 publications

Organized Nanostructured Complexes of Polyoxometalates and Surfactants that Exhibit Photoluminescence and Electrochromism

Organized Nanostructured Complexes of Polyoxometalates and Surfactants that Exhibit Photoluminescence and Electrochromism

Complementary base-pair-facilitated electron tunneling for electrically pinpointing complementary nucleobases

Phase Transitions in Two‐dimensional Adlayers at Electrode Surfaces: Thermodynamics, Kinetics, and Structural Aspects

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