Stabilities of cubane type [Fe4S4(SR)4]2− clusters in partially aqueous media

The stability of cubane-type [Fe4S4(SR)4]2− clusters in mixed organic/aqueous solvents was examined as an initial step in the development of stable water-soluble cluster compounds possibly suitable for reconstitution of scaffold proteins in protein biosynthesis. The research involves primarily spectrophotometric assessment of stability in 20–80% Me2SO/aqueous media (v/v), from which it was found that conventional clusters tend to be stable for up to 12 h in 60% Me2SO but are much less stable at higher aqueous content. α-Cyclodextrin mono- and dithioesters and thiols were prepared as ligand precursors for cluster binding, which was demonstrated by spectroscopic methods. A potentially bidentate cyclodextrin dithiolate was found to be relatively effective for cluster stabilization in 40% Me2SO, suggesting (together with earlier results) that other exceptionally large thiolate ligands may promote cluster stability in aqueous media.

Graphical AbstractThe solution stabilities of the clusters [Fe4S4(SR)4]2− in Me2SO/water solvent were examined, including new clusters of α-cyclodextrin thiolates.Figure optionsDownload full-size imageDownload as PowerPoint slide