Supramolecular Chirogenesis Engineered by Pt(II)···Pt(II) Metal-Metal Interactions

Supramolecular chirogenesis represents an effective way to induce chirality at the supramolecular level. For the previous host-guest chirogenic systems, metal–ligand coordination, hydrogen bonding, π-π stacking and hydrophobic interactions have been mainly employed as the non-covalent driving forces. In this study, Pt(II)···Pt(II) metal-metal interactions have been engineered to induce supramolecular chirogenesis, by forming non-covalent clipping structures between chiral platinum receptors and achiral platinum guests together. It results in the emergence of Cotton effects in the metal-metal-to-ligand charge transfer region, ascribed to chirality transfer from trans-1,2-diamide cyclohexane unit on chiral receptors to Pt(II)---Pt(II) non-covalent interacting sites. Supramolecular chirogenesis can be further transferred from organic to aqueous solutions, with higher resistance to concentration and temperature variations in the latter medium. Overall, the current study provides new avenues toward supramolecular chirality systems with tailored properties.

Chiral recognition and enantiomer excess determination based on emission wavelength change of AIEgen rotor

Chiral recognition, such as enantioselective interactions of enzyme with chiral agents, is one of the most important issues in the natural world. But artificial chiral receptors are much less efficient than natural ones. For tackling the chiral recognition and enantiomer excess (ee) analysis, up until now all the fluorescent receptors have been developed based on fluorescence intensity changes. Here we report that the chiral recognition of a large number of chiral carboxylic acids, including chiral agrochemicals 2,4-D, is carried out based on fluorescent colour changes rather than intensity changes of AIEgen rotors. Moreover, the fluorescence wavelength of the AIEgen rotor linearly changes with ee of the carboxylic acid, enabling the ee to be accurately measured with average absolute errors (AAE) of less than 2.8%. Theoretical calculation demonstrates that the wavelength change is ascribed to the rotation of the AIEgen rotor upon interaction with different enantiomers.

Imprinted micelles for chiral recognition in water: shape, depth, and number of recognition sites

Molecular imprinting within cross-linked micelles yielded chiral receptors with excellent enantio- and diastereoselectivity for amino acid derivatives.