Molecular-based electronics

Besides self-assembly on the surface of metals, another example of self-assembly is the formation of Langmuir-Blodgett monolayers on the surface or at the interface of liquids.47,48 One approach to molecular-based electronic devices that has made use of self-assembled Langmuir-Blodgett films is the crossbar-based defect-tolerant approach to molecular computing 49 Rotaxane molecules that depend on physical dislocations within the molecule to produce switching functionality have been designed such that they will... 

The following sections consider the likely future developments in specific areas of molecular electronics and considers the role that interfacial supramolecular assemblies may play in fabricating molecular-scale and molecular-based electronic devices. 

Membrane characteristics, such as membrane potential and ion permeability, can be controlled by photoirradiation when photoisomerizable chromophores are incorporated into the membrane. The membrane can fabricate an organic-photosensor, which changes the potential in an on-off fashion when light irradiation is used as an input signal. Such an application of organic membranes is of considerable interest in connection with the development of molecular based electronic devices. 

Molecular-based electronic devices used as active components in nanoelectronics were r eeently p roposed [ 1 ]. The b asic function o f su ch d evices i s a t wo-terminal molecular junction that can be electrically switched between high- and low-conductance states. Rational design of the switching molecule can be employed to optimize the switching characteristics because they are mainly dependent on the properties of the molecule. 

In the development and fabrication of molecular-based electronics, it is essential to have a good understanding of the chemistry and electronic struemre of the electroactive polymer interface with other polymers, semi-conductors and metals. A better understanding of the CT interactions at the polymer/metal interface will also facilitate the application of conductive polymer coatings for metal passivation and corrosion prevention [268]. An overview of measurement methods and quantum chemical calculation techniques for smdying the chemical and electronic structure of conjugated... 

The abihty to measure and to control charge transport across nanometer-scale metal-molecule-metal junctions represents a key step toward the realization of molecular-based electronics [190-192]. Various experimental approaches have been employed to study molecular junctions in two- and three-terminal configurations. These include scanning probe microscopies (STM, STS, CP-AFM) [193-208], crossed-wire junctions [209], mechanical [210-215] and electromigration [216,217] break junctions, nanopores [218] and mercury drop electrodes [219]. Approaches in condensed media, and in par-... 

The exertion of precise control over the spatial arrangement of metal-complexes is of considerable interest for the development of molecular-based electronic and magnetic materials. With this in mind, our own work turned towards exploiting the stacked conformation of planar metal-complexes within box-shaped host 1 to generate specific metal-metal interactions. Following the addition of bisacetylacetonato metal-complexes 4 (M = Pt(II), Pd(II), and... 

As holds for other cluster systems, certain magic cluster electron counts exist, which indicates for a certain cluster-halide ratio and interstitial present the filling of all bonding molecular orbitals and therefore the thermodynamically most stable situation. For main group interstitial atoms these are 14 cluster-based electrons whereas for transition-metal interstitials the magic number is 18 [1, 10-12]. All of these phases are synthesized by high-temperature solid-state chemical methods. A remarkable variety of different structure types has been... 

Ames Laboratory (Iowa State University, USA) investigating new solid state phases based on reduced rare earth halides. Since 1993, she has held a position at the University Jaume 1 of Castello (Spain) and became Associate Professor of Physical Chemistry in 1995. During the second semester of 2005, she held a visiting professor position at the Laboratory of Chemistry, Molecular Engineering and Materials of the CNRS-Universtity of Angers (France). Her research has been focussed on the chemistry of transition metal clusters with special interest in multifunctional molecular materials and the relationship between the molecular and electronic structures of these systems with their properties. She is currently coauthor of around 80 research papers on this and related topics. 

Based on the same underlying principles as the molecular-based quantum methods, solid-state DFT represents the bulk material using periodic boundary conditions. The imposition of these boundary conditions means that it becomes more efficient to expand the electron density in periodic functions such as plane waves, rather than atom-based functions as in the molecular case. The efficiency of the calculations is further enhanced by the use of pseudo-potentials to represent the core electrons and to make the changes in the electron density... 

Second, in designing new molecule-based electronic devices, one of the major goals is the precise control of the current flowing between the terminals. Electrochemical molecular junctions allow for control of the potentials of the electrodes with respect to the redox potential of incorporated redox-active molecules with well-defined, accessible, tunable energy states. These junctions represent unique systems able to predict precisely at which applied potential the current flow will take off. Even though the presence of a liquid electrolyte represents a detriment towards possible applications, they provide the concepts for designing molecular devices that mimic electronic functions and control electrical responses. 

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