Inclusion complexation behavior of dyestuff guest molecules by a bridged bis(cyclomaltoheptaose)[bis(beta-cyclodextrin)] with a pyromellitic acid diamide tether.
A novel bridged bis(beta-cyclodextrin) with a pyromellitic acid 2,5-diamide tether (2) has been synthesized by reaction of 6(I)-(2-aminoethyleneamino)-6-deoxycyclomaltoheptaose [mono 6-(2-aminoethyleneamino)-6-deoxy-beta-cyclodextrin] with 1,2,4,5-benzenetetracarboxylic dianhydride. Its inclusion complexation behavior with some representative dyestuffs, i.e., Acridine Red (AR), Rhodamine B (RhB), Neutral Red (NR), Brilliant Green (BG), was studied by using UV-absorption, fluorescence, and 2D NMR spectroscopy. Fluorescence titrations have been performed at 25 degrees C in pH 7.2 buffer solution to calculate the binding constants of resulting complexes. These results obtained indicated that bis(beta-cyclodextrin) 2 exhibits the strongly enhanced binding ability with all dye molecules examined compared with natural cyclodextrins. The binding modes of 2 with dye molecules have been deduced by 2D NMR experiments to establish the correlations between molecular conformations and binding constants of inclusion complexation. It is found that the improved binding ability and molecular selectivity of 2 could be attributed to double-cavity cooperative inclusion interaction and the size/shape matching between the host and guest.
Liu
Yu
Y
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Weijin Road 94, Tianjin 300071, PR China. yuliu@public.tpt.tj.cn
Li
Li
L
Zhang
Heng-Yi
HY
Liang
Peng
P
Wang
Hao
H
D000577:Amides / Q000737:chemistry*; D001565:Benzoates / Q000737:chemistry*; D001665:Binding Sites; D001952:Bridged-Ring Compounds / Q000138:chemical synthesis*; D004396:Coloring Agents / Q000737:chemistry*; D003505:Cyclodextrins / Q000138:chemical synthesis*; D005456:Fluorescent Dyes / Q000737:chemistry; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence; D047392:beta-Cyclodextrins
D000577:Amides; D001565:Benzoates; D001952:Bridged-Ring Compounds; D004396:Coloring Agents; D003505:Cyclodextrins; D005456:Fluorescent Dyes; D047392:beta-Cyclodextrins; C012018:pyromellitic acid; C031215:betadex