Stretching-Induced Conductance Increase in a Spin-Crossover Molecule

Abstract

We investigate transport through mechanically triggered single-molecule switches that are based on the coordination sphere-dependent spin state of Fe(II)-species. In these molecules, in certain junction configurations the relative arrangement of two terpyridine ligands within homoleptic Fe(II)-complexes can be mechanically controlled. Mechanical pulling may thus distort the Fe(II) coordination sphere and eventually modify their spin state. Using the movable nanoelectrodes in a mechanically controlled break-junction at low temperature, current-voltage measurements at cryogenic temperatures support the hypothesized switching mechanism based on the spin-crossover behavior. A large fraction of molecular junctions formed with the spin-crossover-active Fe(II)-complex displays a conductance increase for increasing electrode separation and this increase can reach 1-2 orders of magnitude. Theoretical calculations predict a stretching-induced spin transition in the Fe(II)-complex and a larger transmission for the high-spin configuration.

Fragmentation and Distortion of Terpyridine-Based Spin-Crossover Complexes on Au(111)

“…Similar complexes have been investigated in controlled break-junction experiments. 41,52 Complex 1 was deposited on Au(111) using ESI. Prior to deposition, the molecular ion beam was analyzed by an in-line quadrupole mass spectrometer.…”

Enhanced Separation Concept (ESC): Removing the Functional Subunit from the Electrode by Molecular Design

“…Numerous systems have been reported being addressed by various stimuli like e.g. light,, mechanical manipulation,, electrochemical gating,, the applied voltage, or the electrical current , . We became recently interested in E ‐field triggered molecular junctions and developed a variety of model compounds sensing this parameter.…”

Constructive Quantum Interference in Single‐Molecule Benzodichalcogenophene Junctions

“…When as ingle molecule is connected to source and drain electrodes, the electrical conductance of the resulting device is controlled by the quantumi nterference (QI) pattern within the molecule, created by de Brogliew aves of electrons injected into the molecule by the source. [1] Stimulated by the desire to develop molecular-scale diodes, [2][3][4] transistors, [5,6] switches [7][8][9][10] and thermoelectric devices [11][12][13] with improvedp erformance, recente ffort has been devoted to exploiting such wave patterns within heterocyclic aromatic molecules.P olyaromatic hydrocarbons( PAHs) and their derivatives are particularly attractive, becauset hey contain multiple interfering pathways, which promote QI and can be influenced by external electrostatic or electrochemical gating, [14] by varyingt heir connectivities to external electrodes [15,16] or by heteroatom substitution. [17] When the core of ag raphene-like PAHi sw eakly coupled to external electrodes by atoms i and j,t he single-molecule electrical conductance s i,j depends on the choice of connecting atoms i, j.…”