ABSTRACT
The binding constants (log Kass ) of small synthetic receptor molecules based on indolocarbazole, carbazole, indole, urea and some others, as well as their combinations were measured for small carboxylate anions of different basicity, hydrophilicity and steric demands, that is, trimethylacetate, acetate, benzoate and lactate, in 0.5 % H2 O/[D6 ]DMSO by using the relative NMR-based measurement method. As a result, four separate binding affinity scales (ladders) including thirty-eight receptors were obtained with the scales anchored to indolocarbazole. The results indicate that the binding strength is largely, but not fully, determined by the strength of the primary hydrogen-bonding interaction. The latter in turn is largely determined by the basicity of the anion. The higher is the basicity of the anion the stronger in general is the binding, leading to the approximate order of increasing binding strength, lactate
ABSTRACT
Neutral 1,3-di(1H-indol-7-yl)ureas are selective dihydrogen phosphate receptors in polar solvent mixtures (DMSO-d(6)-25% water).
ABSTRACT
The anion-binding properties of two similar hybrid amide/urea macrocycles containing either a 2,6-dicarboxamidophenyl or a 2,6-dicarboxamidopyridine group are compared. Significant differences in anion affinity and mode of interaction with anions are attributed to the presence of intramolecular hydrogen bonds in the pyridine system. In fact, remarkably, the phenyl macrocycle undergoes amide hydrolysis under neutral conditions in DMSO/water. The anion binding abilities of the receptors are compared to those of acyclic analogues of the macrocycles that show that the phenyl receptor behaves in a similar fashion to acyclic urea-containing receptors (i.e., showing little selectivity amongst oxo anions), whilst the pyridine-containing receptor shows a high affinity and selectivity for carboxylates.
Subject(s)
Amides/chemistry , Macrocyclic Compounds/chemistry , Urea/chemistry , Anions , Benzoates/chemistry , Binding Sites , Crystallography, X-Ray , Dicarboxylic Acids/chemistry , Dimethyl Sulfoxide/chemistry , Hydrogen Bonding , Hydrolysis , Models, Chemical , Molecular Conformation , Picolinic Acids/chemistry , Water/chemistryABSTRACT
A macrocyclic amidourea shows anion dependent binding modes with a variety of different putative anionic guests.
ABSTRACT
A simple bis-urea containing anion receptor, synthesised from ortho-phenylenediamine, has been shown to have excellent selectivity for carboxylates in solution, with a crystal structure elucidation of the benzoate complex showing four hydrogen bonds between the receptor and anion in the solid state.
Subject(s)
Carboxylic Acids/chemistry , Benzoates/chemistry , Dimethyl Sulfoxide , Hydrogen Bonding , Indicators and Reagents , Magnetic Resonance Spectroscopy , Models, Molecular , Phenylurea Compounds/chemistry , SolutionsSubject(s)
Calixarenes/chemistry , Porphyrins/chemistry , Crystallography, X-Ray , Ions , Molecular StructureABSTRACT
Steric interactions in 1,3-dicarboxamidoanthraquinones have been employed to 'twist' isophthalamide-like anion binding sites; the crystal structure of the fluoride complex of a bis-3,5-dichlorophenylamide derivative shows the receptor acting as a 'hydrogen-bonding corner' in a '2 + 2' fluoride containing molecular box.
