Cyclodextrins as pharmaceutical solubilizers.

Supramolecular Chirality in Self-Assembled Systems

Chirality-Sensing Supramolecular Systems

Supramolecular chemistry has expanded dramatically in recent years both in terms of potential applications and in its relevance to analogous biological systems. The formation and function of supramolecular complexes occur through a multiplicity of often difficult to differentiate noncovalent forces. The aim of this Review is to describe the crucial interaction mechanisms in context, and thus classify the entire subject. In most cases, organic host-guest complexes have been selected as examples, but biologically relevant problems are also considered. An understanding and quantification of intermolecular interactions is of importance both for the rational planning of new supramolecular systems, including intelligent materials, as well as for developing new biologically active agents.

Binding Mechanisms in Supramolecular Complexes

This review highlights the past six year advances in the blossoming field of cucurbit[n]uril chemistry. Because of their exceptional recognition properties in aqueous medium, these pumpkin-shaped macrocycles have been generating some tremendous interest in the supramolecular community. They have also become key units in various self-organizing and stimulus-controlled assemblies, as well as in advanced materials and drug carriers. The scope of this review is limited to the main family of cucurbit[n]urils (n = 5, 6, 7, 8, 10). The reader will find an overview of their preparation, their physicochemical and biological properties, as well as their recognition abilities towards various organic and inorganic guests. Detailed thermodynamic and kinetic considerations, as well as multiple applications including supramolecular catalysis are also discussed.

Cucurbituril chemistry: a tale of supramolecular success

For the first time, achiral cucurbiturils (CBs) were endowed with significant enantiomeric and distereomeric discrimination by incorporating a strong chiral binder. Calorimetric, nuclear magnetic, light-scattering, and mass spectral studies revealed that (S)-2-methylbutylamine (as a strong binder) can be discriminated by two enantiomeric supramolecular hosts, composed of CB[6] and (R)- or (S)-2-methylpiperazine, with an unprecedented 95% enantioselectivity in aqueous NaCl solution. This is the highest enantioselectivity ever reported for a supramolecular system derived from an achiral host. Similarly, CB[7], with a larger cavity, exhibited diastereoselectivities up to 8 times higher for diastereomeric dipeptides, as demonstrated for L-Phe-L-Leu-NH3+ versus L-Phe-D-Leu-NH3+.

Chiral recognition in cucurbituril cavities.

The achiral syn folded conformer (face-to-face) of the ethane-bridged bis(Zn porphyrin) gradually transforms into the chiral extended anti form in the presence of enantiopure guest molecules (alcoh...

Temperature Effect on Supramolecular Chirality Induction in Bis(zinc porphyrin)

Critical difference in chiral recognition of N-Cbz-D/L-aspartic and -glutamic acids by mono- and bis(trimethylammonio)-beta-cyclodextrins.

Complexation mechanism, binding properties and thermodynamic parameters of supramolecular chirality induction in the achiral host molecule, syn (face-to-face conformation) ethane-bridged bis(zinc porphyrin), upon interaction with chiral monoamine and monoalcohol guests have been studied by means of the UV-vis, CD, (1)H NMR, and ESI MS techniques. It was found that the chirogenesis process includes three major equilibria steps: the first guest ligation to a zinc porphyrin subunit of the host (K(1)), syn to anti conformational switching (K(S)), and further ligation by a second guest molecule to the remaining ligand-free zinc porphyrin subunit (K(2)), thus forming the final bis-ligated species possessing supramolecular chirality. The validity of this equilibria model is confirmed by the excellent match between the calculated and experimentally observed spectral parameters of the bis-ligated species. The second ligation proceeds in a cooperative manner as K(2) > K(1) for all supramolecular systems studied, regardless of the structure of the chiral ligand used. The binding properties are highly dependent on the nature of the functional group (amines are stronger binders than alcohols) and on the structure of the chiral guests (primary and aliphatic amines have overall binding constant values greater than those of secondary and aromatic amines, respectively).

Supramolecular chirogenesis in zinc porphyrins: equilibria, binding properties, and thermodynamics.

The complexation behavior, binding properties, and spectral parameters of supramolecular chirality induction in the achiral host molecule, syn (face-to-face conformation) ethane-bridged bis(zinc po...

Supramolecular Chirogenesis in Zinc Porphyrins: Interaction with Bidentate Ligands, Formation of Tweezer Structures, and the Origin of Enhanced Optical Activity

Yoshihisa Inoue

Papers

Chiral recognition in cucurbituril cavities.

Temperature Effect on Supramolecular Chirality Induction in Bis(zinc porphyrin)

Critical difference in chiral recognition of N-Cbz-D/L-aspartic and -glutamic acids by mono- and bis(trimethylammonio)-beta-cyclodextrins.

Supramolecular chirogenesis in zinc porphyrins: equilibria, binding properties, and thermodynamics.

Supramolecular Chirogenesis in Zinc Porphyrins: Interaction with Bidentate Ligands, Formation of Tweezer Structures, and the Origin of Enhanced Optical Activity