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

Multi-State Regulation of the Dihydrogen Phosphate Binding Affinity to a Light- and Heat-Responsive Bis-Urea Receptor

“…It can be seen that stable cis - 1 strongly and preferentially binds H 2 PO 4 – and that CH 3 CO 2 – binding is also substantial. These K a values are in similar range as those previously reported for other successful bis-urea receptors. − …”

Synthesis, Characterization, and Luminescence Properties of a New Series of Eu3+-Containing Macrocycles

“…The bis-isothiocyanate 3 is stable in the presence of H 2 O under these conditions, and the reaction proceeds in good yield. Previous syntheses of macrocyclic thioureas (that lack a metal chelating group) through the reaction of bis-isothiocyanates with diamines under high dilution (2 mM in CHCl 3 ) have resulted in similar yields, 70−79% 12b. In the current work, the synthetic scheme producing 4 − 7 maintains the higher yields particular to the isothiocyanate reaction, while also producing a DTPA-containing macrocycle.…”

Metal template effect on O-alkylation of tetrathiacalix[4]arene with 2-bromoacetamide to afford tetrakis(carbamoylmethoxy)thiacalix [4]arenes with cone and 1,3-alternate conformation

“…Thus, the peak of OCH 2 CON protons at 4.68 and 4.50 ppm were assigned to cone and 1,3-alternate conformers, respectively; the latter one was folded into thecavity formed by the inverted benzene rings and thus shifted 9,[21][22][23] Several examples of the formation of intramolecular hydrogen-bonding among opposing urea groups which can bind anionic species in calix [4]arenes have been reported. [24][25][26] Therefore, intramolecular hydrogen bonding may be foreseen between the NH and CO groups. In order to investigate the existence of intramolecular hydrogen bonding in 4 the reference compound 6 was synthesised in 80% yield by O-alkylation of 5 27 sol.…”