Distinguishing Different Isomers of the Photochromic CMTE Molecule on the Si(100) Surface Studied by STM

Abstract

The adsorption of the cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (CMTE) molecule on the clean Si(100)-2 × 1 surface was studied using scanning tunneling microscopy at room temperature. These molecules belong to the class of photochromic dye molecules that undergo reversible photoisomerization between the open and closed isomers when irradiated with light. This is the first observation of individual photochromic molecules on a surface where it is possible to identify the two photoisomers. By changing the ambient lighting conditions prior to deposition, the relative proportion of the two forms of molecules observed on the silicon surface can be changed. The deduction is that the triangular form corresponds to the closed isomer, and the three-lobed form corresponds to the open isomer.

Chemical manipulation of multifunctional hydrocarbons on silicon surfaces

“…The continuation of work on large molecules, such as 1,4 -paratriphenyldimethylacetone molecule (trima) [478] as well as an investigation of cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene (CMTE), a photochromic dye, on Si(100)-2×1 [479] is also now available.…”

Photochromic Diarylethenes Designed for Surface Deposition: From Self‐Assembled Monolayers to Single Molecules

“…A possible scenario in which the adsorption configuration is heavily influenced by the surface through the formation of a SiÀ S bond that forces the two thiophene rings in different configurations has been proposed. [79] Meanwhile, in a separate study, Coudret and co-workers observed standing waves when a diarylethene derivative was adsorbed on Cu (111) surface. [80] This pointed to interactions with the Cu surface.…”

“…With the aid of calculations, these were assigned to their o and c forms. A possible scenario in which the adsorption configuration is heavily influenced by the surface through the formation of a Si−S bond that forces the two thiophene rings in different configurations has been proposed …”

STM Investigation of the Photoisomerization and Photodimerization of Stilbene Derivatives on HOPG Surface

“…Understanding and controlling conformational changes of molecules adsorbed on surfaces is one of the most actively pursued goals related to fundamental electronic device miniaturization . So far, many isomerization reactions have been studied for molecules adsorbed on surfaces ,− by activating the reactions via photon excitation, by means of tunnel electrons, or with the electrostatic field under the tip of STM. − …”