title: Gelation-induced visible supramolecular chiral recognition by fluorescent metal complexes of quinolinol-glutamide.
abstract: Three metal complexes consisting of Li(+), Zn(2+), and Al(3+) 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.
authors.affiliation: Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, PR China.
authors.forename: Wangen
authors.initials: W
authors.lastname: Miao
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Wang
authors.forename: Long
authors.initials: L
authors.lastname: Qin
authors.forename: Minghua
authors.initials: M
authors.lastname: Liu
mesh_terms: D000535:Aluminum / Q000737:chemistry; D005453:Fluorescence; D005782:Gels / Q000138:chemical synthesis / Q000737:chemistry; D005973:Glutamine / Q000031:analogs & derivatives / Q000737:chemistry*; D006912:Hydroxyquinolines / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D013499:Surface Properties; D015032:Zinc / Q000737:chemistry
chemical_list: D005782:Gels; D006912:Hydroxyquinolines; D046911:Macromolecular Substances; D009942:Organometallic Compounds; D005973:Glutamine; D008094:Lithium; D000535:Aluminum; D015032:Zinc