Synthesis and Photophysical Analysis of Amphiphilic Azobenzene Surfactants for Photomechanical Actuation

2025/09/26 by Awatef Ayadi, Jongseong Park, Orein F. Jafter +1 · 1 voice
Materials Science · Chemistry · #Photochromic and Fluorescence Chemistry #Polydiacetylene-based materials and applications #Advanced Polymer Synthesis and Characterization

paper · pdf · doi:10.1002/ejoc.202500250

Abstract

Photoswitchable amphiphiles are promising candidates for investigating light‐responsive mechanical behavior in soft and biological systems, with potential applications in dynamic materials and adaptive interfaces. Azobenzene is the most studied photoactuator, but research typically focuses on its standard backbone, limiting control over its photophysical and kinetic properties. Modifying its conjugated core offers new opportunities for tuning its behavior. Here, the synthesis and characterization of water‐soluble azobenzene derivatives featuring a hexaethylene glycol (OCH 2 CH 2 ) 6 unit terminated with a sodium sulfate (OSO 3 Na) group, alongside subtle electronic modifications to the conjugated backbone, are reported. Their steady‐state photophysical properties and reversible photoisomerization kinetics in aqueous environments under real‐time observation are demonstrated. Despite similar activation parameters for the thermal cis – trans isomerization in some derivatives, their half‐lives vary significantly, underscoring the overlooked role of the transmission coefficient in isomerization kinetics. Finally, these photo‐responsive amphiphiles are showcased as dynamic surfactants in oil‐in‐water and water‐in‐oil emulsions, visualizing their behavior through operando microscopy. These findings underscore their potential for tunable emulsions and adaptive soft matter applications.

Citations

• Self-Consistent Molecular-Orbital Methods. IX. An Extended Gaussian-Type Basis for Molecular-Orbital Studies of Organic Molecules
• Thermal half-lives of azobenzene derivatives: virtual screening based on intersystem crossing using a machine learning potential
• Semiempirical GGA‐type density functional constructed with a long‐range dispersion correction
• 6‐31G* basis set for third‐row atoms
• A survey of Hammett substituent constants and resonance and field parameters

Discussions

• Small electronic tweaks → big differences: cis-state half-lives diverge despite similar activation barriers. Their dual solubility makes them photomechanical surfactants, showing distinct behavior in [bsky, 7 points, 0 comments]

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