10.1021/jo902328y.s001
Maria E. Amato
Maria E.
Amato
Francesco P. Ballistreri
Francesco P.
Ballistreri
Salvatore Gentile
Salvatore
Gentile
Andrea Pappalardo
Andrea
Pappalardo
Gaetano A. Tomaselli
Gaetano A.
Tomaselli
Rosa M. Toscano
Rosa M.
Toscano
Recognition of Achiral and Chiral Ammonium Salts by Neutral Ditopic Receptors Based on Chiral Salen-UO<sub>2</sub> Macrocycles
American Chemical Society
2010
phenyl rings
anion
Neutral Ditopic Receptors
Chiral Ammonium Salts
chiral diimine bridge
recognition
chiral quaternary ammonium salts
Lewis acidic uranyl site
MM
TBA
TMA
receptor
CH
cation
NMR
complex
2010-03-05 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Recognition_of_Achiral_and_Chiral_Ammonium_Salts_by_Neutral_Ditopic_Receptors_Based_on_Chiral_Salen_UO_sub_2_sub_Macrocycles/2786419
A mononuclear (<b>M20</b>) and a dinuclear (<b>M40</b>) uranyl chiral macrocyclic complex, incorporating both a salen unit containing two phenyl rings linked to a chiral diimine bridge and the (<i>R</i>)-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), (α-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<sup>−</sup> < Br<sup>−</sup> < Cl<sup>−</sup>), 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.