Reversible Photoisomerization in Thin Surface Films from Azo-Functionalized Guanosine Derivatives

Abstract

Two novel azo-functionalized guanosine derivatives were synthesized, and their photoisomerization process was investigated in molecular monolayers at the air–water interface and in the Langmuir–Blodgett (LB) films on solid substrates. Measurements of surface pressure vs area isotherms, surface potential measurements, UV–visible (vis) absorption spectroscopy, Brewster angle microscopy (BAM), and atomic force microscopy (AFM) were performed. Despite not having a typical amphiphilic molecular structure, the derivatives formed stable films on the water surface. They could also undergo repeated photoisomerization in all of the investigated thin-film configurations. The observations suggest that in the films at the air–water interface, the molecules first exhibit a conformational change, and then they reorient to an energetically more favored orientation. In the LB films transferred onto solid substrates, the isomerization process occurs on a similar time scale as in solution. However, the isomerization efficiency is about an order of magnitude lower than that in solution. Our results show that DNA nucleobases functionalized with azobenzene moieties are suitable candidates for the fabrication of photoactive two-dimensional (2D) materials that can provide all beneficial functionalities of DNA-based compounds.

Regular Arrays of Rod‐Shaped Molecular Photoswitches: Synthesis, Preparation, Characterization, and Selective Photoswitching within Mono‐ and Bilayer Systems

“…In contrast to solid surfaces, photoswitching on liquids is usually accompanied by morphological changes to LB films, often reflected in surface tension. [8,9,22] The third approach involves the mechanochemical anchoring of rigid rod-shaped molecules on flat crystal facets of a porous, organic, zeolite-like matrix known as tris(o-phenylenedioxy)cyclotriphosphazene. Molecular guests featuring bulky stoppers incorporated within their structures have been developed to prevent molecules from being completely inserted into the matrix, thus ensuring the formation of surface inclusions.…”

“…The second approach involves the use of Langmuir‐Blodgett (LB) films, mostly consisting of aliphatic amphiphilic compounds, [20,21] assembled at the water‐air interface. In contrast to solid surfaces, photoswitching on liquids is usually accompanied by morphological changes to LB films, often reflected in surface tension [8,9,22] . The third approach involves the mechanochemical anchoring of rigid rod‐shaped molecules on flat crystal facets of a porous, organic, zeolite‐like matrix known as tris( o ‐phenylenedioxy)cyclotriphosphazene.…”

Synthesis, Characterization and Biological Activity of Azo Dye Derived from 2-methoxyaniline and its Complexes

“…[8][9][10][11][12] The azo guanosine derivatives exhibited a remarkable photoisomerization process in liquid that play important role in biological process and high optic data storage. 13 As a result, we are interested in the synthesis and characterization of new azo ligands for guanine and study their antifungal activity.…”