1156544-65-8Relevant articles and documents
Design of protonated polyazamacrocycles based on phenanthroline motifs for selective uptake of aromatic carboxylate anions and herbicides
Cruz, Carla,Cahsto, Vania,Delgado, Rita,Felix, Vitor
supporting information; scheme or table, p. 3277 - 3289 (2009/12/05)
Three novel large polyazamacrocycles containing two 1,10-phenanthroline (phen) units connected by two polyamine spacers of different length, [32]phen2N4, [30]phen2N6 and Me 2[34]phen2N6, have been synthesised and their protonated forms used as receptors for binding studies with several aromatic carboxylate anions (benzoate (bzc-), 1-naphthalate (naphc -), 9-anthracenate (anthc-), pyrene-1-carboxyl-ate (pyrc-), phthalate, (ph2-), isophthalate (iph 2-), terephthalate (tph2-), 2,5-dihydroxy-1,4- benzenediacetate (dihyac2-) and, 1,3,5-benzenetricarboxylate (btc3-)) and three herbicides (4-amino-3,5,6-trichloropyridine-2- carbox-ylate (ATCP-), dichlorophenoxyacetate (2,4-D-) and glyphosate (PMG2-)) in water solution. The [30]phen2N 6 receptor was found to be the most suitable for binding the anions considered in a 1:1 stoichiometry. The three receptors exhibit a remarkable binding selectivity towards the extended aromatic anion pyre- at low pH values. Their binding affinities for the monocarboxylate anions decrease with the extension of the aromatic system in the order pyre- > anthc- > naphc- > bzc-, which indicates the presence of π-π stacking interactions in the molecular recognition of these anions. Molecular dynamics simulations carried out for the binding of (H4[30]phen2N6}4+ and {H 6Me2[34]phen2N6}6+ with pyre-, anthc-, naphc-, iph2- and btc3- in water showed that these receptors adopt a folded conformation with the anion inserted between the two phen heads and that the molecular recognition is governed by π-π stacking interactions and multiple N-H...O=C hydrogen bonds. The binding free energies estimated theoretically are very similar to those found by Potentiometric methods, which supports the proposed binding arrangement.