Hierarchical Self-Assembly Induced by Dilution-Enhanced Hydrophobic Hydration.

Hydrophobic hydration (HH) is crucial in protein chemistry. Its role in the organization of molecules in water, however, remains elusive and difficult to investigate without appropriate model systems. Metal carbonyl vesicles (MCsomes), assembled from hydrophobic Fp(CH2 )6 Azobenzenetrans (Fp head=(PPh3 )(Cp)Fe(CO)(CO-); hydrocarbon tail=(CH2 )6 Azobenzenetrans ; trans:trans configuration) is dispersible in water via HH of the Fp heads. We examined the dependence of this HH on solution conditions by taking advantage of redox activity and fluorescence quenching ability of hydrated Fe elements. A subtle variation in the HH substantially varied the solution behaviour of the MCsomes for hierarchical structural evolutions. This scrutiny resolved a long-standing challenge to explicate the role of HH in self-assembly at molecular levels, an imperative step to understand the biological systems.