1214990-63-2Relevant academic research and scientific papers
Recognition of achiral and chiral ammonium salts by neutral ditopic receptors based on chiral salen-UO2 macrocycles
Amato, Maria E.,Ballistreri, Francesco P.,Gentile, Salvatore,Pappalardo, Andrea,Tomaselli, Gaetano A.,Toscano, Rosa M.
supporting information; experimental part, p. 1437 - 1443 (2010/06/11)
(Figure Presented) A mononuclear (M20) and a dinuclear (M40) uranyl chiral macrocyclic complex, incorporating both a salen unit containing two phenyl rings linked to a chiral diimine bridge and the (R)-BINOL unit, behaves as an efficient ditopic receptor for achiral and chiral quaternary ammonium salts. Binding affinities in chloroform solution have been measured for 1:1 complexes of many quaternary salts encompassing tetramethylammonium (TMA), tetraethylammonium (TEA), tetrabutylammonium (TBA), and acetylcholine (ACh), as well as trimethylanilinium (TriMAn), benzyltrimethylammonium (BnTriMA), (a-methylbenzyl)trimethylammonium and pyrrolidinium cations. The anion of the salt is bound by the hard Lewis acidic uranyl site, with an increasing binding efficiency on increasing the anion hardness (I- - -), whereas CH-π or π-π attractions by binapthyl moiety, or the salicylaldehyde unit, or the phenyl rings of diimine bridge ensure the recognition of the cation partner. Optimized structures of receptor-anion-cation ternary complexes obtained by MM calculations are supported by 2D-ROESY NMR measurements.
