Reversible photoswitching of stimuli-responsive Si(100) surfaces engineered with an assembled 1-cyano-1-phenyl-2-[4′-(10-undecenyloxy)phenyl]-ethylene monolayer

Abstract

Si(100) surfaces were molecularly engineered by covalent linkage of a monolayer of two stilbene-based chromophores, either 1-cyano-1-phenyl-2-[4 0 -(10-undecenyloxy)phenyl]-ethylene or its chlorine derivative, 1-cyano-1-(4-Cl-phenyl)-2-[4 0 -(10-undecenyloxy)phenyl]-ethylene. The hybrid systems have been probed by monochromatized angle-resolved X-ray photoelectron spectroscopy (AR-XPS) and atomic force microscopy (AFM) measurements. Results indicated robust covalent linkage of stilbene molecules to the functionalized substrate surfaces. AFM lithography and contact angle (CA) analysis confirmed that the adopted molecular architectures proved to be well-suited for reversible cis-trans photoswitching promoted by UV irradiation in the solid state.

Highly Light‐Sensitive Luminescent Cyanostilbene Flexible Dimers

“…[3a,4] Interestingly, their solid state photophysical properties can be tuned in response to a variety of external stimuli, such as heat, light, pressure, solvents, pH or ions. Besides, the cyanostilbene unit shows photochemical activity and it can undergo Z/E isomerization or [2+2]‐cycloaddition reactions. [5o,6] Thus, in recent years, the investigation of this photoreactivity and the associated changes in properties has evolved an interesting topic for developing novel multiresponsive systems.…”

“…Besides, the cyanostilbene unit shows photochemical activity and it can undergo Z/E isomerization or [2+2]‐cycloaddition reactions. [5o,6] Thus, in recent years, the investigation of this photoreactivity and the associated changes in properties has evolved an interesting topic for developing novel multiresponsive systems.…”

“…In order to combine different degrees of packing order and fluidity, the liquid crystal phase has been proposed for cyanostilbene materials. [5g,h,m,o,6b,7] Mesophases offer the possibility to explore the chromophore in different molecular arrangements and correlate them to their physical properties. Furthermore the liquid crystal state has an important role, as the fluid‐like nature has provided interesting phenomena such as photoisomerization‐induced phase transitions,[5g,m] surface relief gratings[5h] and light modulation of the macroscopic properties.…”

“…Furthermore the liquid crystal state has an important role, as the fluid‐like nature has provided interesting phenomena such as photoisomerization‐induced phase transitions,[5g,m] surface relief gratings[5h] and light modulation of the macroscopic properties. [5m,o]…”

“…This study has led to a rich phenomenology in terms of molecular structure and packing arrangements that can be modulated by the number of chromophores (one or two cyanostilbene units), the position of the cyano‐group in the molecule and the length of the terminal alkoxy chains. Crystal polymorphism and bent‐core liquid crystal phases (SmCP, DC‐SmCP, Col r , and B 6 mesophases)[5o,7m,n] have been reported. The emission behavior of these compounds is sensitive toward the state of aggregation and can be modulated using external stimuli such as temperature and light.…”