Vesicular Membrane with Structured Interstitial Water

Abstract

Self-assembled vesicles with structured (tetrahedral order with strong hydrogen bonds) interstitial water are reported. The vesicles, known as MCsome, are assembled from metal carbonyl compounds, FpR (Fp = (Cp)­Fe­(PPh3)­(CO)­(CO−), Cp = cyclopentadiene, R = C3Bithiophene, C6Pyrene or C6) with the Fp heads exposed to water. The R groups are surrounded by the interstitial water with the hydrogen bonding strength variable depending on the hydrophobicity of R groups. The structure of the interstitial water is responsible for the integrity of the membrane and swelling behavior of the vesicles. This constructional role of water opens new concepts for the creation of aqueous assemblies with water-mediated functions.

Aqueous Self-Assembly of Hydrophobic Molecules Influenced by the Molecular Geometry

“…Water takes part in biological assembling processes, which has constructional roles in addition to acting as a solvent. , Hydrophobic molecules can be hydrated, known as hydrophobic hydration, but the hydration water can be easily repelled resulting in the hydrophobic collapse. − This is the conventional concept of hydrophobic effects (HE). , Guided by this effect, most building blocks used for aqueous self-assembly are amphiphiles and require water-soluble groups to maintain the suspension of the assembles in water . However, proteins and synthetic hydrophobic molecules − without water-soluble groups are also able to undergo aqueous self-assembly, which usually trap water within the assemblies. − The trapped inner water was found to be crucial for the colloidal stability. ,− …”