Quantifying Hydrogen-Bonding Interactions in the Self-Assembly\nof Photoresponsive Azobenzene Amphiphiles at the Air–Water\nInterface

Amphiphilic\nazobenzene molecules offer ample scope to design functional\nsupramolecular systems in an aqueous medium that can be controlled\nby light. Despite their widespread applications in photopharmacology\nand optoelectronics, the self-assembly pathways and energy landscapes\nof these systems are not well understood. Here, we report combined\nmolecular dynamics (MD) simulation and surface manometry studies on\na specially designed alkylated, meta-substituted azobenzene derivative\nto quantify the hydrogen-bonding interactions in the self-assembled\nmonolayers of its photoisomers. The <i>z</i>-density profile,\nradial distribution function, order parameters, and hydrogen bond\nanalyzed using MD simulations corroborated the experimental observations\nof changes in surface pressure, dipole moment, and thickness of the\nmonolayers. Even a small change in the number of hydrogen bonds in\nthe molecule–molecule and molecule–water interactions\ncauses significant changes in the monolayer properties. These results\nare fundamentally important for engineering photoresponsive molecules\nwith tailored properties for applications in targeted drug delivery\nand other industrial applications.