Self-Assembled Monolayers of Molecular Conductors with Terpyridine-Metal Redox Switching Elements: A Combined AFM, STM and Electrochemical Study

Self-assembled monolayers (SAMs) of terpyridine-based transition metal (ruthenium and osmium) complexes, anchored to gold substrate via tripodal anchoring groups, have been investigated as possible redox switching elements for molecular electronics. An electrochemical study was complemented by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) methods. STM was used for determination of the SAM conductance values, and computation of the attenuation factor β from tunneling current–distance curves. We have shown that SAMs of Os-tripod molecules contain larger adlayer structures compared with SAMs of Ru-tripod molecules, which are characterized by a large number of almost evenly distributed small islands. Furthermore, upon cyclic voltammetric experimentation, Os-tripod films rearrange to form a smaller number of even larger islands, reminiscent of the Ostwald ripening process. Os-tripod SAMs displayed a higher surface concentration of molecules and lower conductance compared with Ru-tripod SAMs. The attenuation factor of Os-tripod films changed dramatically, upon electrochemical cycling, to a higher value. These observations are in accordance with previously reported electron transfer kinetics studies

Electrochemical Characterization of Self-Assembled Monolayers Containing Redox Switching Element

Adsorption properties of molecules containing [Ru(terpy)2]2+ and [Os(terpy)2]2+ redox switching element connected to the electrode surface by tripodal thiolate anchoring groups have been studied together with their charge transfer properties in the adsorbed form. STM-based current-voltage measurements confirmed that the conductance of self-assembled monolayer containing [Os(terpy)2]2+ redox switching element is lower than that containing [Ru(terpy)2]2+ element. This observation agrees with previously observed differences in the electron transfer rate constants of these molecules in their adsorbed state

Chronopotentiometry of Papain Modified by Ruthenium Complexes

Catalytic hydrogen evolution reaction is one of known effects observed during the electrochemical studies of proteins. Constant current chronopotentiometric stripping technique is suitable tool for the study of catalytic hydrogen evolution reaction due to the formation of peak H. This contribution compares the catalytic behaviour of nonmodified papain and its artificial derivatives prepared by the interaction of organometallic complexes of ruthenium with free sulfhydryl group of protein. The comparison of the chronopotentiometric behaviour of papain and its derivatives would help to better understand the catalytic hydrogen evolution reaction in these derivatives

Influence of Adsorption on Electrochemical Reduction of Pyridinium Derivatives

Two expanded pyridinium-based compounds 1 and 2 were studied by cyclic voltammetry in two different environments. The nonaqueous solution suppresses the adsorption of the compounds on the electrode surface. Adsorption process in aqueous environment was confirmed by typical shape of the curve as well as by the linear dependence of peak current on the scan rate. The shift of standard redox potential in aqueous solution compared to nonaqueous environment toward more negative potential indicates the adsorption of reactant on the electrode surface. Larger shift observed for flat conjugated molecule 1 confirms its stronger adsorption than for the second molecule

Electrochemical Characterization of Molecular Conductors Containing Redox Switching Element

Electrochemical properties of new molecules containing tripodal anchor and redox switching\nelement have been studied by cyclic voltammetry and DFT quantum mechanical calculations.\nComparison of their redox properties with individual organometallic [Ru(terpy)2]2+t3+ and\n[Os(terpy)2]2+t3+ redox centers shows that covalently bonded tripodal anchor does not\ncompromise the reversibility of a redox process and has no effect on the stability of new\nmolecules. New molecular conductors have smaller HOMO-LUMO gap and both are oxidized\nat only slightly more positive potentials after tripodal substitution making them suitable for the\ndevelopment of molecular conductors with switching abilities

Self-Assembled Monolayers of Molecular Conductors with Terpyridine-Metal Redox Switching Elements: A Combined AFM, STM and Electrochemical Study

Self-assembled monolayers (SAMs) of terpyridine-based transition metal (ruthenium and osmium) complexes, anchored to gold substrate via tripodal anchoring groups, have been investigated as possible redox switching elements for molecular electronics. An electrochemical study was complemented by atomic force microscopy (AFM) and scanning tunneling microscopy (STM) methods. STM was used for determination of the SAM conductance values, and computation of the attenuation factor β from tunneling current–distance curves. We have shown that SAMs of Os-tripod molecules contain larger adlayer structures compared with SAMs of Ru-tripod molecules, which are characterized by a large number of almost evenly distributed small islands. Furthermore, upon cyclic voltammetric experimentation, Os-tripod films rearrange to form a smaller number of even larger islands, reminiscent of the Ostwald ripening process. Os-tripod SAMs displayed a higher surface concentration of molecules and lower conductance compared with Ru-tripod SAMs. The attenuation factor of Os-tripod films changed dramatically, upon electrochemical cycling, to a higher value. These observations are in accordance with previously reported electron transfer kinetics studies

On the Supra‐LUMO Interaction: Case Study of a Sudden Change of Electronic Structure as a Functional Emergence

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Electron Storage System Based on a Two-Way Inversion of Redox Potentials

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