Computing with Molecules

Reed, Mark A.; Tour, James M.

doi:10.1038/scientificamerican0600-86

Cited by 262 publications

(170 citation statements)

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“…41,42 Despite the well-known issue that B3LYP may be inadequate to account for the dispersion interaction which is a significant contribution to the interaction between CBPQT and TTF/ DNP, 16,19 it should still be adequate in describing the difference between the interactions at different oxidation states, since the variation of the dispersion interaction for different oxidation states should be minor compared to the variation of the electrostatic interaction. At the final geometry, the solvation energy in AN (dielectric constant 35.69, density 0.7857 g/cm 3 at 20°C, 43 probe radius 2.18 Å) is also calculated in B3LYP/ 6-31G** (since the solvation energy is not very sensitive to the choice of basis set 42 ) using the Poisson-Boltzmann continuum-solvation model. 44,45 The following atomic radii are used (in Å): 42 H 1.15, C 1.9, N 1.6, O 1.6, F 1.682, P 2.074, and S 1.7 (which has been changed from 1.9 to reproduce the experimental reduction potentials of TTF).…”

Section: Methodsmentioning

confidence: 99%

Mechanism of Oxidative Shuttling for [2]Rotaxane in a Stoddart−Heath Molecular Switch: Density Functional Theory Study with Continuum-Solvation Model

Jang

Goddard

2006

J. Phys. Chem. B

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The central component of the programmable molecular switch demonstrated recently by Stoddart and Heath is [2]rotaxane, which consists of a cyclobis-(paraquat-p-phenylene) ring-shaped shuttle [(CBPQT 4+ )(PF 6 -) 4 ] encircling a finger and moving between two stations on the finger: tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP). We report here a quantum mechanics (QM) study of the mechanism by which movement of the ring (and in turn the on-off switching) is controlled by the oxidation-reduction process. We use B3LYP density functional theory to describe how oxidation of the [2]rotaxane components (in using PoissonBoltzmann continuum-solvation theory for acetonitrile solution) induces the motions associated with switching (translation of the ring). These calculations support the proposal that oxidation occurs on TTF, leading to repulsion between two positive charge centers (TTF 2+ and CBPQT 4+ ) that drives the CBPQT 4+ ring from the TTF 2+ station toward the neutral DNP station. The theory also supports the experimental observation that the first and second oxidation potentials are nearly the same (separated by 0.09 eV in the QM). This excellent agreement between the QM and experiment suggests that QM can be useful in designing new systems.

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Section: Methodsmentioning

confidence: 99%

Mechanism of Oxidative Shuttling for [2]Rotaxane in a Stoddart−Heath Molecular Switch: Density Functional Theory Study with Continuum-Solvation Model

Jang

Goddard

2006

J. Phys. Chem. B

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“…In addition, oligomeric materials with defined length and constitution have become important subjects of their own [8]. One of the emerging and most challenging areas for monodisperse conjugated oligomers is molecular scale electronics, in which single or small packets of molecules function as the active channels for information transportation, processing, and storage [9,10]. Constructing electronic devices with organic molecules can overcome the fundamental physical restraints in traditional Si-based technologies and can also result in a rapid and low-cost bottom-up manufacturing process for electronic device fabrication.…”

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confidence: 99%

The cationization mechanism study of novel oligo (p-phenyleneethynylene)s

Chen

et al. 2005

J. Am. Soc. Mass Spectrom.

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Two series of new oligo(p-phenyleneethynylene)s (OPEs) O1-O4 and O5-O8, which have been proven to be one of the chief classes of molecules mainly used as the wires and other potential backbones of molecular electronic devices, have been synthesized by stepwise synthetic approach. The characterization of these oligomers was performed on MALDI TOF MS. Different cationization salts have been applied to investigate the ionization processes of these series of oligomers under MALDI conditions. The experimental results show that these oligomers display a strong tendency to undergo radical cationization and varied ionization efficiency with different cationization agents attributable to their difference in cationic diameters. Furthermore, we found that these two series of oligomers differed in ionization properties because of their different end-groups even when the same cationization agent was used. (J Am Soc Mass Spectrom 2005, 16, 1695-1701

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“…The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current-voltage characteristics, similar to the phenomena in a semiconductor diode. molecular electronics ͉ rectification ͉ single-molecule studies T he idea to build an electronic device based on single molecules is today called Molecular Electronics (1)(2)(3)(4). Conceptually and historically, this field starts out from electron transfer physics (5) and chemistry (6,7), where a single electron is transferred within a molecule.…”

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confidence: 99%

A single-molecule diode

Elbing

Ochs

Koentopp

et al. 2005

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

463

390

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We have designed and synthesized a molecular rod that consists of two weakly coupled electronic -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current-voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur-gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current-voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current-voltage characteristics, similar to the phenomena in a semiconductor diode. molecular electronics ͉ rectification ͉ single-molecule studies

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Computing with Molecules

Cited by 262 publications

References 0 publications

Mechanism of Oxidative Shuttling for [2]Rotaxane in a Stoddart−Heath Molecular Switch: Density Functional Theory Study with Continuum-Solvation Model

Mechanism of Oxidative Shuttling for [2]Rotaxane in a Stoddart−Heath Molecular Switch: Density Functional Theory Study with Continuum-Solvation Model

The cationization mechanism study of novel oligo (p-phenyleneethynylene)s

A single-molecule diode

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