A ligand-chirality controlled supramolecular hydrogel

We report a novel example of ligand-chirality finely controlled in situ supramolecular hydrogel formation based on the coordination of phenylalanine (Phe) to Cu(II) with higher selectivity over other metal ions. As decreasing both enantiomeric excesses (ee%) of ligand Phe towards its D-and L-forms, the gelation ability of Phe-Cu(II) supramolecular metallogelator was found to be weakened and eventually disappeared, which likely resulted from the stereoselectivity of the ligand Phe. Intermolecular hydrogen bonding, hydrophobic and/or pi-pi stacking interactions were also found to be essential for forming the metallogel. We believe that the present work can open up a new entry for developing novel and promising chiral sensing and recognition platforms, i.e. visually sensing chiral molecules by naked eyes due to the feature of a sol-to-gel transition induced smartly by varying the ligand chirality.CAS [09i4281c10]; NSF of China [20835005

Anion-triggered melamine based self-assembly and hydrogel

We found that melamine in its protonated form could be triggered by oxoanions such as NO3-, PO43-, ATP, and SO42- to form superstructures and to gelate a large amount of water molecules, presumably resulting from the electrostatic and hydrogen bonding interactions operating in a synergistic manner; the gelation can be reversibly switched off/on by increasing/decreasing pH or temperature.CAS [09i4281c10]; NSF of China [20835005