title: Syntheses and Metal Ion Complexation of Novel 8-Hydroxyquinoline-Containing Diaza-18-Crown-6 Ligands and Analogues.
abstract: Ten new 8-hydroxyquinoline-containing diaza-18-crown-6 ligands and analogues were synthesized via a one-pot or stepwise Mannich reaction, reductive amination, or by reacting diaza-18-crown-6 with 5,7-dichloro-2-iodomethyl-8-quinolinol in the presence of N,N-diisopropylethylamine. The Mannich reaction of N,N'-bis(methoxymethyl)diaza-18-crown-6 with 4-chloro-2-(1H-pyrazol-3-yl)phenol gave the NCH(2)N-linked bis(3-(5-chloro-2-hydroxy)pyrazol-1-ylmethyl)-substituted diazacrown ether (14) in a 98% yield. The reaction of bis(N,N'-methoxymethyldiaza)-18-crown-6 with 2.2 equiv of 10-hydroxybenzoquinoline gave only the monosubstituted diazacrown ether ligand (8). Interaction of some of the ligands with various metal ions was evaluated by a calorimetric titration technique at 25 degrees C in MeOH. Bis(8-hydroxyquinoline-2-ylmethyl)-substituted ligand 13 forms a very strong complex with Ba(2+) (log K = 11.6 in MeOH) and is highly selective for Ba(2+) over Na(+), K(+), Zn(2+), and Cu(2+) (selectivity factor > 10(6)). The (1)H NMR spectral studies of the Ba(2+) complexes with bis(8-hydroxyquinoline-2-ylmethyl)- and bis(5,7-dichloro-8-hydroxyquinoline-2-ylmethyl)-substituted diaza-18-crown-6 ligands (13 and 10) suggest that these complexes are cryptate-like structures with the two overlapping hydroxyquinoline rings forming a pseudo second macroring. UV-visible spectra of the metal ion complexes with selected ligands suggest that these ligands might be used as chromophoric or fluorophoric sensors.
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602.
authors.forename: Ning
authors.initials: N
authors.lastname: Su
authors.forename: Jerald S.
authors.initials: JS
authors.lastname: Bradshaw
authors.forename: Xian Xin
authors.initials: XX
authors.lastname: Zhang
authors.forename: Huacan
authors.initials: H
authors.lastname: Song
authors.forename: Paul B.
authors.initials: PB
authors.lastname: Savage
authors.forename: Guoping
authors.initials: G
authors.lastname: Xue
authors.forename: Krzysztof E.
authors.initials: KE
authors.lastname: Krakowiak
authors.forename: Reed M.
authors.initials: RM
authors.lastname: Izatt