Electron transfer processes through organic molecules have been studied extensively i) in the last 30 years using transient spectroscopy in donor-acceptor supramolecular systems1 ii) in the last decade using an electrochemical approach in self assembled monolayers (SAMs) organized at an electrode interface. 2 We report a series of studies of electron transfer processes carried out by measuring current flowing though molecules in metal-molecules-metal junctions. We used two different types of junction: a two electrodes junction and in a four electrodes junction. In the first case, we correlate electron transfer rate with the chemical structure of molecules, by measuring the current flowing through SAMs sandwiched between two electrodes (Fig 1a,b).3,4,5,6 The junctions are based on Hg electrodes: Hg-SAM//SAM-M, where M is a metal surface (Au, Ag, Hg), are easy to assemble and are compatible with SAMs incorporating organic molecules having a range of structures. When photoactive molecules are incorporated into the SAMs, the current flowing through the junction changes upon irradiation of the SAMs. In the second type of junction (Fig 1c,d), that incorporates redox sites, the potentials of the electrodes respect to the potential of the redox center are controlled: The current flowing between the electrodes shows the behaviour of a solid state transistor.
Self Assembled Monolayers organized between two Metal Surfaces. Correlation between Electrical Properties and Molecular Structure.
RAMPI, Maria Anita
2005
Abstract
Electron transfer processes through organic molecules have been studied extensively i) in the last 30 years using transient spectroscopy in donor-acceptor supramolecular systems1 ii) in the last decade using an electrochemical approach in self assembled monolayers (SAMs) organized at an electrode interface. 2 We report a series of studies of electron transfer processes carried out by measuring current flowing though molecules in metal-molecules-metal junctions. We used two different types of junction: a two electrodes junction and in a four electrodes junction. In the first case, we correlate electron transfer rate with the chemical structure of molecules, by measuring the current flowing through SAMs sandwiched between two electrodes (Fig 1a,b).3,4,5,6 The junctions are based on Hg electrodes: Hg-SAM//SAM-M, where M is a metal surface (Au, Ag, Hg), are easy to assemble and are compatible with SAMs incorporating organic molecules having a range of structures. When photoactive molecules are incorporated into the SAMs, the current flowing through the junction changes upon irradiation of the SAMs. In the second type of junction (Fig 1c,d), that incorporates redox sites, the potentials of the electrodes respect to the potential of the redox center are controlled: The current flowing between the electrodes shows the behaviour of a solid state transistor.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
