Neutral Anion Receptors with Multiple Urea-Binding Sites

Abstract

The synthesis of macrocyclic and acyclic cleft-like anion stoichiometry (K a = 10 7 M -2 ) in DMSO, whereas Clis bound in a 1:1 stoichiometry (K a = 10 3 M -1 ). The macrocyclic receptors receptors in which four hydrogen bond donating urea moieties are present in a preorganized fashion is described. NMR form a 1:1 complex with H 2 PO 4 -(K a = 10 3 M -1 in DMSO) with a 100-fold selectivity for H 2 PO 4 over Cl -. spectroscopy shows the complex formation with H 2 PO 4 and Cl -. Cleft-like receptors bind H 2 PO 4 in a 2:1 guest-host constants ranging from 100 to 4600  Ϫ1 and with a 2Ϫ3[a] Department of Supramolecular Chemistry and Technology, stituents were reduced with Raney Nickel and hydrazine to

A Theoretical ab initio Study of the Capacity of Several Binding Units for the Molecular Recognition of Anions

“…[3] However, the design and synthesis of receptors capable of binding anionic guests is of considerable interest in the context of sensing and removal of environmental contaminants such as nitrate [4] or the radioactive pertechnate produced in the nuclear fuel cycle. [5] Synthetic receptors for anions are usually based on macrocyclic polyammonium/ guanidinium, [6,7] amides, [8,9] urea/thiourea, [10,11] and functionalized calixarenes. [12,13] The binding of anions to neutral receptors is of special significance since it avoids the competing counterion complexes present if cationic hosts are used and improves selectivity due to the dominance of directional interactions, [14] which explains the high specificity of neutral anion binding proteins.…”

“…In this paper we report on a study, using high level ab initio calculations, of the binding capabilities of several aro- matic rings (see Figure 1) with the bromide anion as the target, and we compare them with three molecules that have traditionally been used as binding blocks for building neutral anion receptors, namely urea, [10] thiourea [11] and squaramide, [24] each of which interacts with the anion through two hydrogen bonds. It is worth mentioning that we use two aromatic compounds that have not previously been studied as potential units for binding anions, namely 1,3,5-tricyanobenzene and 1,4,5,8,9,12-hexaazatriphenylene (HAT), and we compare them with two other aromatic rings, s-triazine and hexafluorobenzene, that have already been proposed as anion-binding units.…”

Second‐Sphere Biomimetic Multipoint Hydrogen‐Bonding Patterns to Boost CO2 Reduction of Iron Porphyrins

“…Our choice of introducing urea groups in the second coordination sphere of an iron‐porphyrin catalyst was motivated by their ability to bind oxygen atoms of carbonyl groups as well as carbonates . In some cases, urea groups can even capture atmospheric CO 2 as carbonates/bicarbonate .…”

A Highly Selective Fluorescent Chemosensor for H2PO4– Based on a Calix[4]arene Tetraamide Derivative

“…Furthermore, the 1 H NMR spectral and X-ray crystal studies suggested that multiple hydrogen-bonding interactions occur between 5 and H 2 PO 4 -. tive receptors for anions based on amides have been successfully developed [16,17,[19][20][21][22][23][24] due to their neutral and hydrogen-bond acceptor properties. [24] Compared with amides, sulfonamide-based receptors for anions are rare, even though they have a strong binding ability with anions and are readily available.…”