Dual Guest [(Chloride)₃-DMSO] Encapsulated Cation-Sealed Neutral Trimeric Capsular Assembly: Meta-Substituent Directed Halide and Oxyanion Binding Discrepancy of Isomeric Neutral Disubstituted Bis-Urea Receptors

Abstract

A logically synthesized ortho-phenylenediamine based chloro-methyl disubstituted neutral organic bis-urea receptor L 1 with the aid of three symmetry-independent units encapsulates an unusual triangular [(chloride)3-DMSO] guest assembly (complex 1a) via formation of DMSO + host + salt cocrystals within its trimeric paddle-wheel shaped cavity sealed by three n-TBA cations and exhibits diverse anion binding properties with oxyanions along with the chloride complex of its isomeric bromo-methyl disubstituted bis-urea receptor L 2 . Receptor L 2 and L 1 both form a similar kind of noncapsular 2:2 host–guest assembly in the presence of excess chloride (complex 2a) and acetate (complex 1b) respectively by noncooperative H-bonding interactions of urea groups which are attributed to the effect of meta-functionalization with respect to the adjacent N–H part of the urea moiety, whereas another planar oxyanion carbonate is doubly encapsulated within the tetrameric capsular cavity of L 1 in the solid state (complex 1c). Moreover, receptor L 2 conforms to a similar kind of cation sealed 2:1 host–guest pseudocapsular complex in the presence of larger coordinating anions such as tetrahedral sulfate (complex 2b) and octahedral hexafluorosilicate (complex 2c). 1H NMR titration experiments are also performed using n-TBA/TEA salts of anions to investigate the solution state anion binding behavior of isomeric L 1 and L 2 and corroborate the results obtained in the solid-state studies.

Supramolecular Chemistry of Anionic Dimers, Trimers, Tetramers, and Clusters

“…Manna and coworkers 40 also synthesized the two disubstituted bisurea-based receptors 23 and 24 (Figure 11). It was found that the ortho -phenylenediamine based chloromethyl disubstituted receptor 23 can form a trimeric capsular assembly that encapsulates an unusual triangular [Cl 3 -DMSO] 3− cluster.…”

Crystal structures of the 2:2 complex of 1,1′-(1,2-phenylene)bis(3-m-tolylurea) and tetrabutylammonium chloride or bromide

“…Furthermore, an orthophenylenediamine bis-urea with para-nitro substitution receptor has also been reported, three of which enclose one PO 4 3anion by 12 hydrogen bonds (Li et al, 2013), whilst the bis-urea isomer with meta-nitro substitution displayed good selectivity for carboxylate anions forming a 2:1 complex between receptor and anion (Moore et al, 2013). Very recently, an ortho-phenylenediamine based 3-chloro-4-methyl disubstituted bis-urea receptor and its isomeric 4-bromo-3methyl disubstituted bis-urea receptor have been reported and their affinity with the common anions such as Cl À , AcO À , CO 3 2-, SO 4 2and SiF 6 2has also been studied (Manna et al, 2016). Especially, the 4-bromo-3-methyl disubstituted bis-urea forms non-capsular 2:2 host-guest assemblies with chloride ions via non-cooperative hydrogen-bonding interactions of the urea moieties.…”

Self-Assemblies of Solvates, Ionic Cocrystals, and a Salt Based on 4-{[(4-Nitrophenyl)carbamoyl]amino}-N-(pyrimidin-2-yl)benzene-1-sulfonamide: Study in the Solid and Solution States

“…Noncovalent self-assemblies of drug-based functionalized drugs have generated diverse interest. − The urea has the prospect of functionalizing with a drug or a functional moiety, as the self-assembly properties of urea derivatives − have largely contributed to supramolecular catalysis − and anion binding. − Urea-based ligands are used to prepare cage-like assemblies and host–guest complexes, making them prominent candidates for derivatives with a drug or another functional moiety to explore new avenues. Urea-containing metal–organic frameworks are useful in catalysis and ion recognition. − The surfactant self-assemblies of urea derivatives have been identified to enhance drug efficacy .…”