Reversible Photoisomerization in Thin Surface Films from Azo-Functionalized Guanosine Derivatives
Year: 2021
Journal: ACS Omega, Volume 6, JUN 15, page 15421–15430
Authors: Licen, Matjaz; Masiero, Stefano; Pieraccini, Silvia; Drevensek-Olenik, Irena
Organizations: Slovenian Research Agency (ARRS) [P1-0192, J7-9399]; University of Bologna (RFO)
Two novel azo-functionalized guanosme 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 larea isotherms, surface potential measurements, LTV 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 reheated 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 lmoieties are suitable candidates for the lfabrication of photoactive that can provide all beneficial functionalities of DNA-based compounds.
