Broken Symmetry of an Adsorbed Molecular Switch Determined by Scanning Tunneling Spectroscopy

Abstract

An asymmetric turn: Scanning tunneling spectroscopy has been used to analyze the structure of tris[4-(phenylazo)phenyl)]amine on a Au(111) surface. A degenerate marker state serves as a sensitive probe for the structure of the adsorbed molecules.

Reversible Photoswitching and Isomer‐Dependent Diffusion of Single Azobenzene Tetramers on a Metal Surface

“…This approach ensures stable adsorption through the tripod linker and an upright arrangement of the molecular switch unit, and thus electronic decoupling from the surface. When integrating two or three azobenzene groups into one and the same molecule, the flexible structure of these molecules resulted in flat conformations on the surface, as all azobenzene moieties were adsorbed planar. Hence, a vertical orientation and/or the electronic decoupling of the switching units from the surface was not achieved, and molecular architectures that contain several switching units and maintain their three‐dimensional conformation upon adsorption at a surface were not realized so far.…”

Switching of an Azobenzene-Tripod Molecule on Ag(111)

“…TPAPA comprises three AB units connected via an amino linker in a 3-fold symmetric fashion. − We demonstrate that each of the AB subunits may be reversibly and selectively switched between two states by injecting electrons. Switching may also be triggered by passing current through the central amino nitrogen atom.…”

“…Models are overlaid over some molecules to show their orientations, which are similar to TPAPA on Au(111). 23 In the interior of the island it is a priori not clear which set of protrusions belongs to a given molecule. The molecules at island edges, however, provide a clear indication of the position of the outer phenyl rings.…”

“…This distinct depression at the position of the N−N azo-bridge is in qualitative agreement with previous STM data from AB on metal substrates. 3,8,17,23,27,40 The average intermolecular distance extracted from STM images is (1.7 ± 0.2) nm, and the molecular lattice is rotated by (8 ± 2)°with respect to the compact directions of Ag(111). We note in passing that most islands observed were almost enantiopure.…”

Computational design of a molecular triple photoswitch for wavelength-selective control

“…The switching behavior and the photochromic characteristics of four para -bisazobenzene derivatives connected by aryl–aryl linkers between two AB moieties were studied in an effort to optimize the photoswitching efficiency of linear multi-azobenzenes 19. Furthermore, other multi-photochromic compounds containing multiple switching subunits such as cyclo -trisazobenzene,24–26 tris -[4-(phenylazo)-phenyl]-amine27,28 on a surface, and other multi-photochromic compounds29–36 have been addressed to explore new multi-photochromic effects and light-induced functionalities as well. More recently, orthogonal and reversible control of two distinct types of photoswitches in a multifunctional molecular system has been reported, giving rise to impressive dual functionality 36,37.…”