Crystal structure of pyrogallol[4]arene complex with phosphocholine: A molecular recognition model for phosphocholine through cation–π interaction

Selective recognition of choline phosphate by tripodal hexa-urea receptors with dual binding sites: crystal and solution evidence

Two tripodal hexa-urea receptors functionalized with aromatic terminal groups are capable of binding choline phosphate (CP). Crystal structures of the host-guest complexes reveal that the zwitterion CP is efficiently encapsulated in the tripodal hosts in a dual-site binding mode. The phosphate tail of CP is coordinated by the urea groups and the quaternary ammonium head is bound in a 'composite aromatic box' through cation-π and hydrogen-bonding interactions. Such a partial aromatic binding environment for the Me3N-+ cation mimics that of most enzymes catalyzing the conversion of quaternary ammonium substrates. Moreover, NMR, ESI-MS, and fluorescence studies demonstrate the selective binding and sensing of CP over other competing species such as ADP, ATP, choline and derivatives.

Process Development for Separation of Conformers from Derivatives of Resorcin[4]arenes and Pyrogallol[4]arenes

Macrocyclic compounds, such as resorcin[4]arenes and pyrogallol[4]arenes, have proven to be useful building blocks in the construction of supramolecular organic frameworks (SOFs) because of their unique bowl-like shape and ability to interact through variety of intermolecular interactions. Herein, we report the synthesis and crystal structures of two functionalized resorcin[4]arenes and pyroagllol[4]arenes, 4-hydroxyphenylresorcin[4]arenes, and 4-hydroxyphenylpyrogallol[4]arenes. These phenyl-functionalized macrocycles usually have different conformers, such as cone, boat, chair, saddle, and diamond. The successful separation of predominant conformers from the crude product was carried out with solvent-extraction technique. The shape and molecular arrangement of these conformers in the individual crystal structure was verified with single-crystal X-ray diffraction studies.

Engineering supramolecular organic frameworks (SOFs) of C-alkylpyrogallol[4]arene with bipyridine-based spacers

Supramolecular organic frameworks (SOFs) based on pyrogallol[4]arene and 4,4′-bipyridine-type spacer molecules have been investigated.