Dipole moments of polyenic oligomeric systems. Part II—molecular organic wire resistivities: polyacetylenes, allenes and polyynes

Abstract

Polyacetylenic, allenic and polyynic molecular wire series, containing electron‐donor (D) and electron‐acceptor (A) groups as two terminal units of the oligomeric bridge (D–wire–A), can be well described by means of a one‐dimensional conduction model, which considers a scattering process of electrons through the charge‐transfer conduction bridge. The conduction constants (γi) of the oligomeric structures of the three molecular series under study were determined from the functional dependence between the dipole moment of the oligomers (μn) and the π‐molecular orbital bridge length (L). According to our one‐dimensional molecular organic wire model: where μo is the dipolar moment of the first compound of the oligomeric series without a bridge unit (n = 0) and μ∞ is a limit value for L → ∞. By means of the Landauer theoretical expression for the conductance of a metallic one‐dimensional conductor and our molecular wire conduction constants (γi), we determined the intrinsic resistivities associated with the molecular resistances of these oligomeric wires. Using this approach we determined, for the first time, the linear and non‐linear contributions to the net molecular resistivity. The order of magnitudes of the linear resistivities determined in these oligomeric systems agrees very well with the expected results of experimental measurements for macroscopic wires. Copyright © 2005 John Wiley & Sons, Ltd.

Cyanopolyynes as Organic Molecular Wires in the Interstellar Medium

“…A few years ago, we developed a one-dimensional conduction model for D-W-A molecular systems [15,17]. Our model consider a scattering process of electrons through the internal charge transfer conduction bridge (W) to determine the molecular resistance and the molecular resistivity by means of the linear and non-linear contributions derived from the dipole moments and the -molecular orbital bridge length (L) as fundamental physicochemical parameters.…”

“…Thus, the inner conductance of this molecular wire determines the molecular resistance, and the final charge distribution determines the dipole moment. This model can be applied to any oligomeric molecular system that preserves the orientation of the dipole moment through the main axis of the molecular wire [17]. The molecular wire length and the dipole moment due to the ground-state chargetransfer process induced by the CN group are two fun-damental parameters of the ground electronic state of these cyanopolyynes.…”

“…Whenever this kind of molecular wires has been a subject of long data research, particularly associated to the concept of molecular electronic device [11][12][13][14], previous studies on polyenic systems in our laboratory were based on the electronic conduction properties of conjugated oligomeric compounds of the D-W-A type [14][15][16][17]. These studies have permitted us to focus our attention on these interstellar cyanopolyynes.…”

Comparison of CC Triple and Double Bonds as Spacers in Push–Pull Chromophores

“…The electronic and nonlinear optical properties of D–A‐substituted oligoenes and ‐ynes have been compared in theoretical studies 23,24. D–A‐substituted allenes have also been included in one theoretical comparison 25…”

The Laser Synthesis of Linear Polyynes: The Particle in a Box Revisited

“…The temperature program (80 °C isothermal for 5 min., ramp at 5 °C/min to 130 °C) is a shortened version of that found in the literature (4). A Restek Rtx-1MS column is used (30 m, 0.25 mm i.d., 0.25 μm).…”