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Configuration‐ and Conformation‐Dependent Electronic‐Structure Variations in 1,4‐Disubstituted Cyclohexanes Enabled by a Carbon‐to‐Silicon Exchange
Author(s) -
Emanuelsson Rikard,
Löfås Henrik,
Wallner Andreas,
Nauroozi Djawed,
Baumgartner Judith,
Marschner Christoph,
Ahuja Rajeev,
Ott Sascha,
Grigoriev Anton,
Ottosson Henrik
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201402610
Subject(s) - cyclohexanes , conformational isomerism , chemistry , cyclohexane , molecule , electronic structure , computational chemistry , stereochemistry , crystallography , organic chemistry
Cyclohexane, with its well‐defined conformers, could be an ideal force‐controlled molecular switch if it were to display substantial differences in electronic and optical properties between its conformers. We utilize σ conjugation in heavier analogues of cyclohexanes (i.e. cyclohexasilanes) and show that 1,4‐disubstituted cyclohexasilanes display configuration‐ and conformation‐dependent variations in these properties. Cis ‐ and trans ‐1,4‐bis(trimethylsilylethynyl)cyclohexasilanes display a 0.11 V difference in their oxidation potentials (computed 0.11 V) and a 0.34 eV difference in their lowest UV absorption (computed difference between first excitations 0.07 eV). This is in stark contrast to differences in the corresponding properties of analogous all‐carbon cyclohexanes (computed 0.02 V and 0.03 eV, respectively). Moreover, the two chair conformers of the cyclohexasilane trans isomer display large differences in electronic‐structure‐related properties. This enables computational design of a mechanically force‐controlled conductance switch with a calculated single‐molecule ON/OFF ratio of 213 at zero‐bias voltage.