Chemically Controlled Conductivity: Torsion‐Angle Dependence in a Single‐Molecule Biphenyldithiol Junction

Vonlanthen, David; Mishchenko, Artem; Elbing, Mark; Neuburger, M. L.; Wandlowski, Thomas; Mayor, Marcel

doi:10.1002/anie.200903946

Cited by 152 publications

(206 citation statements)

References 45 publications

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“…[136][153]- [157] Single molecules in electronic circuits can be integrated in various experimental setups to measure their conductance. Such measurements enable basic investigations of the correlation between the molecular structure and transport properties.…”

Section: Biphenylic Compoundsmentioning

confidence: 99%

“…In particular the electron density in the phenyl rings [267] and the torsion angle between both phenyl rings play an important role in the transport properties through a biphenylic system. [157][177] [179] The systematic variation of the torsion angle ( in biphenyl subunits with almost negligible alterations in electronic properties of the phenyl rings was found to show a linear correlation of the single molecule conductance with the cos 2 of the torsion angle. [179] A new approach towards novel molecular switches and memory devices based on structures is introduced here.…”

Section: Switchable Conducting Azo Biphenylsmentioning

confidence: 99%

“…[157] (B) The interplanar torsion angle can by varied between by altering the conformation of the azo functionality.…”

Section: Figure 55 (A)mentioning

confidence: 99%

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Shape‐Switchable Azo‐Macrocycles

et al. 2009

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The synthesis of four shape‐switchable macrocycles comprising different peripheral substituents is described. The macrocycles 1–4 consist of m‐terphenyl semicircles interlinked by two azo joints. These macrocycles were assembled from nitro‐functionalized m‐terphenyl moieties through reductive dimerization. The semicircles were assembled through Suzuki cross‐coupling reactions. The molecular weights of the macrocycles were determined by vapour pressure osmometry, because mass spectrometry failed in the cases of 2 and 3. The E → Z photoisomerization reactions were analysed by UV/Vis spectroscopy complemented by 1H NMR studies. A very slow thermal back‐reaction indicated considerable stabilization of the Z isomer. The reduced efficiency of the thermal back‐reaction probably arises from the reduced degree of freedom due to the mechanical interlinking of the two azo groups. The photostationary state consisted of all‐Z (85 %) and all‐E isomers (15 %). The E → Z transformation induced by irradiation displayed simple exponential kinetics, which indicates pairwise switching of the two azo groups in a macrocycle, at least on the timescale under investigation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Biphenylic Compoundsmentioning

confidence: 99%

Section: Switchable Conducting Azo Biphenylsmentioning

confidence: 99%

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Shape‐Switchable Azo‐Macrocycles

et al. 2009

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“…The design of both is based on our recent findings in molecular electronics which showed a considerable delocalization of the π-system in rod-like oligo phenylene ethynylene (OPE) [8,9] on the one hand and a partition of the π-system by conjugation interrupting subunits like e.g. platinum complexes [10], perpendicular torsion angles [11,12] 3 -carbon which disables conjugation between the neighboring aromatic subunits. In contrast to that, the π-system of the rod-like OPE 2 extends over all three phenyl rings.…”

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confidence: 99%

Quantum interference distinguishes between constitutional isomers

et al. 2010

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Matter waves, as introduced by de Broglie in 1923 [1], are a fundamental quantum phenomenon, describing the delocalized center of mass motion of massive bodies and we show here their sensitivity to the molecular structure of constitutional isomers.In quantum textbooks, matter wave phenomena are often associated with the equation λ dB = h/(mv), where the de Broglie wavelength λ dB is only determined by Plancks constant h and the particles momentum p = mv. It is a common conjecture that this relation still holds for bodies of arbitrary mass, size and complexity. But what is the role of the detailed internal molecular composition if λ dB does not include any such information?As already shown before [2], the centre of mass motion can be well described by quantum delocalization and interference of each entire molecule with itself -even if the internal atoms may populate a thermal mixture of vibrational and rotational modes at a temperature of about T = 500 K. The conceptual separation of the internal and external degrees of freedom allows us to discuss two different cases:If the interaction between the molecule and its environment makes it possible, even only in principle, to retrieve position information, the initially delocalized particle will be localized and quantum interference can no longer occur [3].The second case is of particular relevance for our present experiment: All individual atoms in a given molecular structure will add up to determine its global properties, and in particular also its electrical susceptibility. The susceptibility can couple to an external electric field and thus influence the center of mass motion of the entire particle. In this way, the internal structure becomes influential for the external motion, even though the molecule remains still widely delocalized and capable of showing de Broglie interference.First experiments along this line were recently able to apply this idea to near-field interferometry for measuring the static [4] and optical [5] polarizability α stat and α opt as well as the total electric susceptibility χ tot of molecules. The latter may also contain additional information about static or time varying electric dipole moments [6]. It has therefore been suggested that different molecular conformations might eventually also be distinguished in quantum interference experiments [7].For demonstration purposes we here compare two tailor-made model compounds 1 and 2. The design * http://www.quantumnano.at; markus.arndt@univie.ac.at † marcel.mayor@unibas.ch of both is based on our recent findings in molecular electronics which showed a considerable delocalization of the π-system in rod-like oligo phenylene ethynylene (OPE) [8,9] on the one hand and a partition of the π-system by conjugation interrupting subunits like e.g. platinum complexes [10], perpendicular torsion angles [11,12] or sp 3 -carbon atoms on the other hand. The constitutional isomers 1 and 2 both have the chemical formula C 49 H 16 F 52 and an identical molecular weight of 1592 g mol −1 , but different polari...

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“…6) [104,123]. While the molecules are not exactly the same (various lateral substituents are used to impose the tilt through stearic hindrance), the intrinsic role of these substituents on the electron transport properties of the molecule is negligible compared to the configurational change of the bi-phenyl backbone [104,123].…”

Section: B Configurational Switch and Memorymentioning

confidence: 99%

Molecular Nanoelectronics

Vuillaume

2010

Proc. IEEE

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Abstract-Molecular electronics is envisioned as a promising candidate for the nanoelectronics of the future. More than a possible answer to ultimate miniaturization problem in nanoelectronics, molecular electronics is foreseen as a possible way to assemble a large numbers of nanoscale objects (molecules, nanoparticules, nanotubes and nanowires) to form new devices and circuit architectures. It is also an interesting approach to significantly reduce the fabrication costs, as well as the energetical costs of computation, compared to usual semiconductor technologies. Moreover, molecular electronics is a field with a large spectrum of investigations: from quantum objects for testing new paradigms, to hybrid molecular-silicon CMOS devices. However, problems remain to be solved (e.g. a better control of the molecule-electrode interfaces, improvements of the reproducibility and reliability, etc…).

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Chemically Controlled Conductivity: Torsion‐Angle Dependence in a Single‐Molecule Biphenyldithiol Junction

Cited by 152 publications

References 45 publications

Shape‐Switchable Azo‐Macrocycles

Shape‐Switchable Azo‐Macrocycles

Quantum interference distinguishes between constitutional isomers

Molecular Nanoelectronics

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