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

Abstract

The tripodal hexa-urea receptors functionalized with aromatic terminal groups are able to selectively recognize choline phosphate with dual binding sites.

Molecular Recognition of Zwitterions with Artificial Receptors

“…Lately different scaffolds used in zwitterion recognition have been described: Costa published a receptor based on bis‐squaramides; the group of Moran has published different molecular receptors for the formation of non‐polar host‐guest complexes including a system based in a benzofuran skeleton and two pyridine molecules attached as sulfonamide and carboxamide groups or a receptor based on a chiral chromane . A choline phosphate receptor based on a tripodal hexa‐urea scaffold functionalized with aromatic terminal groups 21 was described by Yang and Wu . The complex is stabilized thanks to the dual binding mode where the phosphate is coordinated by the urea groups and the quaternary ammonium moiety is bound in a ‘composite aromatic box’ through cation‐π and hydrogen bonding interactions.…”

“…[64] A choline phosphate receptor based on a tripodal hexa-urea scaffold functionalized with aromatic terminal groups 21 was described by Yang and Wu. [65] The complex is stabilized thanks to the dual binding mode where the phosphate is coordinated by the urea groups and the quaternary ammonium moiety is bound in a 'composite aromatic box' through cation-π and hydrogen bonding interactions. A binding constants of 1.2 × 10 6 M À 1 in 2% D 2 O-DMSO-d 6 was obtained for this receptor and carnitine.…”

Crystal structure of 4-(3-(pyridin-3-yl)ureido)benzoic acid — adipic acid (2/1), C16H16N3O5

“…As a double hydrogen bond donor, ureido derivatives may form double hydrogen bonds to a Y-type hydrogen bond binding site for example acetate or tetrahedral anions (such as SO4 2− ) [5]. It is more likely that a hydrogen bond may be formed between ureido and ureido, or between ureido and other molecules, etc., which may assemble into supramolecular compounds.…”

Anion-exchange facilitated selective extraction of sulfate and phosphate by overcoming the Hofmeister bias

“…Over the past two decades, several HBD receptors have been developed for the selective recognition of sulfate and phosphates in organic and (semi)aqueous media. 7,8 However, only a limited number of receptors have been demonstrated to selectively separate sulfate and phosphate from aqueous media in the presence of competing anions. 9 Both sulfate and phosphates have higher hydration energies in comparison to chloride, nitrate and other anions (Δ G HE −1080, −465, −350 and −305 kJ mol −1 for SO 4 2− , H 2 PO 4 − , Cl − and NO 3 − , respectively), which makes it challenging for majority of the HBD anion receptors to overcome the Hofmeister bias for sulfate and phosphate separation from water.…”