Chirality is one of the most intriguing property of matter related to the lack of mirror symmetry. Molecules can exist in the two mirror-image structures due to the occurrence of at least one chiral center or a chiral structural arrangement. The transmission of chirality from the molecular up to the macroscopic scale has major implication in life sciences but it is relevant for many applications ranging from catalysis to spintronic. However, its control at nano- and meso-scale is still an open issue that limits its technological application. Here, we demonstrate by a simple approach how chirality can be specifically transferred to a supramolecular system. We describe the formation of stripe features consists of chiral aggregates of a porphyrin derivative on solid substrate in a sub-micrometer-order precision using a modified protocol of a soft lithography. Different from the conventional methods, the polymeric stamp is swelled with an ethanol solution of a chiral inducer reagent and upon contact with a porphyrin aqueous solution J-aggregates are formed. By slow evaporation of the solvent, the solution remains into the protrusions between the substrate surface and stamp, whereas the remaining surface becomes dry. Removal of the stamp results in the formation of a patterned solid features made of porphyrin chiral aggregates. The proposed method successfully allows the fabrication of an ordered distribution of sub-micrometric porphyrin structures in precise and controllable position with programmed chirality, providing a fundamental breakthrough toward the exploitation of chiral materials in technological applications.

Lithographic control of chirality in supramolecular aggregates

ROMEO, Andrea;MONSU' SCOLARO, Luigi;
2016-01-01

Abstract

Chirality is one of the most intriguing property of matter related to the lack of mirror symmetry. Molecules can exist in the two mirror-image structures due to the occurrence of at least one chiral center or a chiral structural arrangement. The transmission of chirality from the molecular up to the macroscopic scale has major implication in life sciences but it is relevant for many applications ranging from catalysis to spintronic. However, its control at nano- and meso-scale is still an open issue that limits its technological application. Here, we demonstrate by a simple approach how chirality can be specifically transferred to a supramolecular system. We describe the formation of stripe features consists of chiral aggregates of a porphyrin derivative on solid substrate in a sub-micrometer-order precision using a modified protocol of a soft lithography. Different from the conventional methods, the polymeric stamp is swelled with an ethanol solution of a chiral inducer reagent and upon contact with a porphyrin aqueous solution J-aggregates are formed. By slow evaporation of the solvent, the solution remains into the protrusions between the substrate surface and stamp, whereas the remaining surface becomes dry. Removal of the stamp results in the formation of a patterned solid features made of porphyrin chiral aggregates. The proposed method successfully allows the fabrication of an ordered distribution of sub-micrometric porphyrin structures in precise and controllable position with programmed chirality, providing a fundamental breakthrough toward the exploitation of chiral materials in technological applications.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3110561
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