EnSurf · Enantioselectivity at surfaces: covalent grafting as new tool for chiral surface modifications

Enantioselectivity at surfaces: covalent grafting as new tool for chiral surface modifications

The term chirality is derived from the Greek word for hand and describes objects which are non-superimposable with their mirror image. Two object related by this mirror symmetry are called enantiomers. Chiral objects can be found everywhere, ranging from artificial objects like screws to the shell of snails down to the molecular level, including all molecules of life, e.g. sugars, DNA and amino acids, which naturally appear only as one of the two possible mirror structures. When chiral molecules interact, their handedness can significantly affect the interaction and as a result opposite enantiomers of the same molecule can, for example, have different smells or in the case of pharmaceuticals different effects. Therefore, the production of enantiopure molecules is particularly important in the pharmaceutical industry, which can be achieved for example by the separation of a racemic mixture via crystallization or separation using high-performance liquid chromatography (HPLC). In HPLC, the creation of homochiral surfaces and the interaction of chiral molecules with these surfaces play are major role. One approach to design and fabricate chiral surfaces is the adsorption and self-assembly of chiral or prochiral molecules on surfaces. Homochiral surfaces can be fabricated either by the adsorption of enantiopure chiral molecules, or by creating a bias in the adsorption of prochiral molecule. Characterization and visualization of these surfaces is possible with sub-molecular resolution by scanning probe microscopy, in particular scanning tunneling microscopy (STM). However, in STM studies dealing with chiral induction, the chiral dopants used are generally enantiopure chiral molecules, i.e. molecular point chirality is required for the fabrication of homochiral surfaces. The overall objectives of this project were the exploration of new methods for chiral induction at surfaces and interfaces. We showed that chiral symmetry breaking based on lateral geometric nanoconfinement can be used to create enantioselectivity in molecular self-assembly under nanoconfinement. Thus, we introduced a new method for chiral symmetry breaking, in which the enantiomorph can be chosen freely during the nanoconfinement creation without the need for any molecular point chirality. In addition to enantioselectivity, the selective formation of concomitant polymorphs could be achieved in lateral nanoconfinement conditions.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз