Phosphine-Functionalized Squaramides as Responsive Organogelators: Structure, Gelation, and Metal-Ion Sensing

Area of Science:

• Supramolecular chemistry
• Materials science

Background:

• Low-molecular-weight gelators (LMWGs) are crucial for developing novel soft materials.
• Squaramides are versatile scaffolds for designing functional LMWGs.

Purpose of the Study:

• To design and evaluate phosphine-functionalized squaramides as organogelators.
• To investigate the influence of structural modifications on gelation properties.
• To explore the responsive behavior of these organogels to metal ions.

Main Methods:

• Synthesis and characterization of phosphine-containing squaramides.
• Organogelation studies in various organic solvents.
• Molecular dynamics simulations to elucidate self-assembly mechanisms.
• Metal ion interaction studies to assess responsiveness.

Main Results:

• Subtle structural changes in phosphine-squaramides significantly impact gelation ability.
• Molecular dynamics confirmed phosphine's role in directing fibrillar network formation.
• Organogels demonstrated selective and rapid collapse upon addition of gold precursors (Au³⁺).
• Other metal ions showed minimal or no effect on gel stability.

Conclusions:

• Phosphine-functionalized squaramides are effective organogelators.
• The phosphine moiety is critical for self-assembly and metal-ion-induced gel collapse.
• These findings enable the development of soft materials with tunable responses to specific metal ions via coordination-driven restructuring.