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Download fileGelation-Induced Visible Supramolecular Chiral Recognition by Fluorescent Metal Complexes of Quinolinol–Glutamide
journal contribution
posted on 07.05.2013, 00:00 authored by Wangen Miao, Li Zhang, Xiufeng Wang, Long Qin, Minghua LiuThree
metal complexes consisting of Li+, Zn2+, and
Al3+ and quinolinol-functionalized l-glutamides
(HQLG), (abbreviated as LiHQLG, Zn(HQLG)2, and Al(HQLG)3) were found to form fluorescent metallogels in several organic
solvents. In solution, these chiral complexes showed neither any CD
signal in the chromophore region nor chiral recognition of the chiral
species. However, upon gel formation, the supramolecular chirality
emerged because of the self-assembled nanostructures, which provided
an opportunity for the chiral recognition of enantiomeric ligands.
The metallogels showed different fluorescence changes when they met
with enantiomeric (R,R)- or (S,S)-1,2-diaminocyclohexane. Among them,
the Al(HQLG)3 metallogels did not show any change whereas
the LiHQLG gels exhibited the same decrease in fluorescence. Interestingly,
the Zn(HQLG)2 gels showed obviously different fluorescent
color with respect to (R,R)- and
(S,S)-1,2-diaminocyclohexane, thus
providing visible chiral recognition via the naked eye. Such different
recognition ability was discussed on the basis of the assembled chiral
nanostructures and the primary molecular structures of the metal complexes.
It was shown that both of them played important roles in chiral recognition.