Yong-Sik Yoo

Carbohydrate-coated nanocapsules from amphiphilic rod-coil molecule: binding to bacterial type 1 pili.

Stable carbohydrate-coated nanocapsules designed as multivalent nanoscaffolds for selective interactions with receptors are able to encapsulate guest molecules within their interior and to bind efficiently to FimH adhesin of bacterial type 1 pili.

1,1′-Disubstituted ferrocene containinghexacatenar thermotropic liquid crystals

The preparation and characterization of ferrocene containing hexacatenar metallomesogens 4a–h based on alkoxy terminal groups with hexyloxy (4a), octyloxy (4b), decyloxy (4c), dodecyloxy (4d), tetradecyloxy (4e), hexadecyloxy (4f), octadecyloxy (4g) and eicosyloxy (4h) chains are described. The introduction of alkyl chains of different lengths induces a rich variety of self-assembled liquid crystalline structures. In the crystalline state, the ferrocene containing hexacatenar metallomesogens 4a–h organize into a microphase-separated monolayer lamellar structure. In contrast, a dramatic phase change after crystalline melting of the metallomesogens is observed with variation of the chain length. The ferrocene containing hexacatenar metallomesogens 4b and c display a bicontinuous cubic mesophase with Ia3d symmetry, while the ferrocene containing hexacatenar metallomesogens 4d–g exhibit a hexagonal columnar mesophase. Further increasing the length of the alkyl chain as in the case of 4h suppresses liquid crystallinity and induces only a crystalline phase. This unique behavior in the ferrocene containing metallomesogenic molecules can be understood to originate from the anisotropic aggregation of ferrocene containing aromatic segments and consequent entropic penalties associated with chain stretching.

Calamitic smectic liquid crystalline supramolecular architecture from octaalkoxy-substituted PdII–η1-benzylideneaniline complexes

Octaalkoxy substituted PdII–η1-benzylideneaniline complexes with a more disc-like shape can give rise to a calamitic smectic phase and low melting transition temperatures comparable to those of the corresponding free ligands.

3-D Organic nanostructures from self-assembly of branched aromatic rods

Self-assembling molecules based on branched aromatic rods, which are prepared by repeating of aromatic coupling reaction and substitution, and flexible dibranched ether-type coils were synthesized. Aggregation behavior could be investigated by optical polarized microscopy, differential scanning calorimetry, and X-ray diffraction. In contrast to the molecule 1 which shows an isotropic liquid state, the more elongated molecules 2 and 3 are observed to organize into a 3-D primitive monoclinic lattice with three distinct nanoscale dimensions, in which rods are tilted with respect to the layer normal.