Enantioselective Molecular Recognition of Chiral Organic Ammonium Ions and Amino Acids Using Cavitand–Salen‐Based Receptors

Abstract

Keywords: Amino acids / Enantioselectivity / Chirality / Molecular recognition / CavitandsTwo new receptors, a cavitand-salen (2) and a uranyl-cavitand-salen (3), for the selective molecular recognition of chiral ammonium ion pairs, where the amino acid is the countercation or counteranion of the ion pair, were designed and synthesized. UV/Vis measurements indicate the formation of 1:1 host-guest complexes with high association constants and good to excellent enantiomeric discriminations.

Supramolecular Detection of a Nerve Agent Simulant by Fluorescent Zn–Salen Oligomer Receptors

“…Non-linear curve fit plots were performed by using a 1:1 stoichiometry, supported by our previous studies on CWA recognition by Metal–Salen complexes [31,32,33,34,35,36,37]. Interestingly, moving from longer to shorter oligomer distribution, an increase of the affinity was observed (see Table 2).…”

“…Metal–Salen complexes are well known in literature for their use as catalysts [26,27,28,29,30] and supramolecular hosts [31,32,33,34,35,36,37,38], where the Lewis acid metal center is exploited for the recognition of Lewis base species. Furthermore, recently we also demonstrated the high efficiency of metal-Salen complexes as receptors for NA simulants [25,39].…”

Fluorescent/luminescent detection of natural amino acids by organometallic systems

“…This is why the U.S. Food and Drug Administration (FDA) has laid down strict guidelines on the identification and quantification of chiral compounds [186][187][188][189]. Therefore, enantioselectivity is one of the most important goals for the sensing of organic substances [190][191][192][193][194][195][196][197][198], because biological activity is strictly correlated with stereochemistry. Although some enantioselective methods based on capillary electrophoresis [199][200], voltammetry [201], colorimetric methods [202][203][204] etc.…”

Nerve Gas Simulant Sensing by a Uranyl–Salen Monolayer Covalently Anchored on Quartz Substrates

“…Aldehyde 3 (270 mg, 2.16 mmol) and diphenylethylendiamine monochlorohydrate [84][85][86][87] (535 mg, 2.16 mmol) were dissolved in am ixture of ethanol/methanol (25 mL, 50:50) and stirred at RT for 24 h. The reaction was monitored by TLC (n-hexane/EtOAc 90:10) and, after total conversion of 3,t he solvent was removed under reduced pressure. The resulting yellow oil was washed with diethyl ether and water to give pure 4 as as olid precipitate, which was filtered and dried (50 %).…”