New chiral metal-mesogenic nanosystems “silver - thiocholesterol” and their adsorption properties

ABSTRACT

New chiral matrices for thin film chromatography were obtained using hybrid metal-mesogenic nanosystems «silver – thiocholesterol» with different metal to ligand ratio, immobilized on silica gel particles. It was shown, that heteroatomic derivative of cholesterol – thiocholesterol and its composition with small silver nanoparticles formed in the system by the chemical reduction of silver ions possess liquid crystalline cholesteric mesophase. Molar ratio between thiocholesterol ligand molecules (L) and silver (Ag) insignificantly influenced on the size of silver nanoparticles formed in the system: for molar ratio Ag : L = 1:5 the main diameter of nanoparticles was equal to (2,7 ± 0,4) nm, for molar ratio Ag : L = 1:2 – (2, 2 ± 0,4) nm, for molar ratio Ag : L = 1:0,5 – (2,1 ± 0,6) nm. The new chiral matrices for thin film chromatography possess enantioselectivity related to optical isomers of 2,2′-diamino-1,1′-binaphtol (DABN) and trifluoroantranylethanol (TFAE). We have succeeded to select optical isomers of TFAE with selecting factor equal to 1,56.

KEYWORDS:

• hybrid metal-mesogenic nanosystems
• thiocholesterol
• silver nanoparticles
• thin layer chromatography
• chiral matrices
• modified silica gel

Acknowledgments

The authors thanks the collaborators from Department of Chemistry, Moscow State University, Chair of analytical chemistry - Dr. E.N. Shapovalova, Dr. N.B. Rozhmanova, and Prof. O.A. Shpigun for fruitful discussions and participation in analytical experiments and Dr. S. Abramchuk for TEM measurements.

The work is financially supported by RFBR grant 13-03-00792-a.