Fluorescent and circular dichroic detection of monosaccharides by molecular sensors: bis[(pyrrolyl)ethynyl]naphthyridine and bis[(indolyl)ethynyl]naphthyridine.
The push-pull conjugated molecules 2,7-bis-(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine (BPN) and 2,7-bis(1H-indol-2-yl)ethynyl-1,8-naphthyridine (BIN) adopting daad relays of proton donors (d) and acceptors (a) form multiple hydrogen-bonding complexes with various monosaccharides that possess complementary adda sequences. Although the free BPN emits blue light at lambda(max) = 475 nm in CH(2)Cl(2), its complexation with octyl beta-d-glucopyranoside gives green fluorescence at lambda(max) = 535 nm. The excellent photophysical properties make BPN a highly sensitive probe for monitoring glucopyranoside to a detection limit of approximately 100 pM. On the other hand, the CD-silent BIN molecule binds with monosaccharides to form the CD-active multiple hydrogen-bonding complexes, which exhibit the remarkable chirality dependent helicities consistent with the prediction by the ab initio approaches. On the basis of the similar daad cleft and hence the binding property, the fluorescence and CD absorption methods in BPN and BIN, respectively, are complementary, which, in combination with computational molecular modeling, not only give a detailed insight into the structures of the receptor-saccharide complexes in solution, but also differentiate octyl beta-d-glucopyranoside from its enantiomer and other monosaccharides.
Fang
Jim-Min
JM
Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan. jmfang@ntu.edu.tw
Selvi
Srinivasan
S
Liao
Jen-Hai
JH
Slanina
Zdenek
Z
Chen
Chao-Tsen
CT
Chou
Pi-Tai
PT
D015374:Biosensing Techniques / Q000379:methods*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D007211:Indoles / Q000737:chemistry*; D008958:Models, Molecular; D009005:Monosaccharides / Q000032:analysis* / Q000737:chemistry; D009287:Naphthyridines / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011758:Pyrroles / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
C486367:2,7-bis(1H-indol-2-yl)ethynyl-1,8-naphthyridine; C471502:2,7-bis(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine; D007211:Indoles; D009005:Monosaccharides; D009287:Naphthyridines; D011758:Pyrroles