A Tripodal Molecule on a Gold Surface: Orientation-Dependent Coupling and Electronic Properties of the Molecular Legs

Abstract

The realization of molecular electronics demands a detailed knowledge of the correlation between chemical groups and electronic function. It has become obvious during the last years that the conformation of a molecule and its coupling to the connecting electrodes plays a crucial role in its conductance behavior and its electronic function, e.g., as a switch. Knowledge about these relationships is therefore essential for future design of molecular electronic building blocks. We present a new three-dimensional molecule, consisting of three identical molecular wires connected to a headgroup. Due to the well-defined spatial arrangement of the molecule in a nonplanar geometry, it is possible to investigate the conductance behavior of these wires with respect to their position and coupling to the surface electrode with the submolecular resolution of a scanning tunneling microscope. The experimental findings are supported by calculations of the electronic structure and conformation of the molecule on the surface by density functional theory with dispersion corrections.

Importance of the Anchor Group Position (Para versus Meta) in Tetraphenylmethane Tripods: Synthesis and Self‐Assembly Features

“…[27,28] Structures tabilization by Vand er Waals forcesi nm onolayers,a nd efficient packing in SAMs,h ave been reported for backbones consisting of C 3 tetrahedral symmetric units equipped with Si or Cc ores. [13,15,29] Our initial attempts toward tripodal modelc ompounds were based on coordinationc omplexes comprising both neutral M III complexes [30,31] and charged tris(bipyridine)-Ru II derivatives, [32] but our recentm olecular designscomprise purely organic scaffolds such as 9,9'-spirobifluorenes. [33] Active-tail groups have been introduced to demonstrate the presenceo ftripodalm olecules on electrodes.…”

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

“…Particularly prominent examples of metal–molecule contacting groups include thiols [46–47], selenols [48–49], dithiocarbamates [50–51], carbodithioates [52], amines [53–54], esters [55], cyano [56–57], isocyanides [58], nitriles [59], carboxylic acids [24,55,60], dithiocarboxylic acids [52], isothiocyanates [61], dimethylphosphine [62], 4-(methylthio)phenyl groups [63], dihydrobenzo[ b ]thiophenes [64], thienyl rings [65], diphenylphosphine group [66], trimethylsilylethynyl groups [67–69] and fullerenes [60,70–71]. However, many of these groups have significant limitations including chemical degradation at working temperatures [72–73], associated polymerization phenomena [74], small binding energies [74], unexpectedly high contact resistance [75–80], and multiple conductance values due to the variability in the binding geometries [81–86]. …”

Electrochemical TERS Elucidates Potential‐Induced Molecular Reorientation of Adenine/Au(111)

“…The adsorption geometry of (re)active molecules is acrucial parameter that determines surface reactivity or device functionality in al arge variety of applications,s uch as heterogeneous catalysis,e lectrochemical (EC) energy conversion, biotechnology,and molecular electronics.F or example,ithas been suggested that the spatial tilt of p-bonds with respect to the substrate strongly influences the catalytic activity or electron conductance of adsorbates. [1][2][3] Accessing adsorbate orientation in relation to specific surface sites in situ or in operando is afirst crucial step toward controlling interfacial geometries for improved device architecture. However,s uitable in situ techniques to study molecular orientation at well-defined adsorption sites are still scarce.…”