Fluorescent and Circular Dichroic Detection of Monosaccharides by Molecular Sensors:  Bis[(Pyrrolyl)ethynyl]naphthyridine and Bis[(Indolyl)ethynyl]naphthyridine

Abstract

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.

Solid-State Examination of Conformationally Diverse Sulfonamide Receptors Based on Bis(2-anilinoethynyl)pyridine, -Bipyridine, and -Thiophene

“…18–21 Addition of simple synthetic handles to the arenes in these systems has allowed for substitution of chiral functional groups, yielding macrocycles capable of saccharide complexation as well as asymmetric catalysis and chiral recognition. 22,23 Of all of the benefits of using an arylethynyl foundation on which to build a receptor, the rigidity, and hence preorganization, they lend to the structure is particularly important. Furthermore, in the case of acyclic receptors, the axial rotation around the linear substituted alkynyl bonds provides receptors that are also conformationally flexible.…”

Systematic Studies on Photoluminescence of Oligo(arylene‐ethynylene)s: Tunability of Excited States and Derivatization as Luminescent Labeling Probes for Proteins

“…[36] In this work, our strategy entails the esterification of oligo(arylene-ethynylene)s with the N-hydroxysuccinimidyl group, which reacts with lysine moieties in proteins and enables the covalent attachment of fluorophores to biomolecules. We have demonstrated that the high quantum efficiencies, large Stokes shifts (maximum 11530 cm -1 ) and strong solvatochromism (except H-and Fsubstituted derivatives) of the oligo(arylene-ethynylene)s can confer rich photophysical characteristics upon the resultant bioconjugates.…”

Synthesis and Fluorescence Sensing Properties of Calix[4]arenes Containing Fluorophores

“…3). Measurement of fluorescence intensity ½I 0 F =ðI F 2I 0 F Þ as a function of the inverse of Na þ concentration fit a linear relationship, indicating a 1:1 stoichiometry for the 4 · Na þ complex [20,21].…”