Cyclodextrin inclusion complexes with thiocholesterol and their self-assembly on gold: A combined electrochemical and lateral force microscopy analysis

• Self-assembled monolayer of inclusion complexes on gold surface
• Lateral force microscopy study of the regions of varying hydrophilicities
• Could find applications in patterning surfaces to be hydrophilic/hydrophobic
• Improved electron transfer barrier properties

The present study is an attempt to understand the properties of an interesting self-assembled monolayer system composed of inclusion complexes of thiocholesterol and cyclodextrins. Cyclodextrins were used as host compound while thiocholesterol was used as the entrant molecule into the cavity of cyclodextrins. The improved electron transfer barrier property towards a redox couple indicates a sturdy inclusion complex monolayer. A very large Rct value, 64.6 kΩ·cm2 for a redox system was obtained in the case of methyl-β-cyclodextrin and thiocholesterol inclusion complex self-assembled monolayer. A rather low value of capacitance 1.2 μF cm− 2 measured in supporting electrolyte further signifies the fact that inclusion complex monolayer is quite impermeable for ionic species. In addition lateral force microscopy combined with force–distance analysis revealed the presence of an interesting mixed hydrophilic/hydrophobic surface.