A π-extended phenanthrene-fused aza[7]helicenium as a novel chiroptically-active architecture in organic and aqueous media

Abstract

The synthesis and characterization of an original π-extended cationic azahelicene is reported. The phenanthrene-fused aza[7]helicene derivative encompasses a total of ten aromatic fused rings leading to a dissymmetric yet helically...

CPL-active water-soluble aromatic oligoamide foldamers

“…The three watersoluble hexameric sequences devoid of additional functional group therefore show slightly lower dissymmetry in emission than sequence 5 in chloroform (g lum = 1.1 x 10 -2 for P-5). Nonetheless, the g lum values reported herein are in the same range of previously reported aza [7]helicenium in H 2 O/MeOH solvent mixture (g lum = 6 x 10 -3 ) 7 and they are significantly higher than that of functionalized binaphthyl fluorophores in water and in MeOH (g lum = 4 x 10 -4 ). 4 As for the fluorescence emission, the electronically enriched sequence 4 exhibits red-shifted CPL signal compared to the non-functionalized water-soluble sequences, yielding CPL emission at  = 558 nm with an associated g lum = 2.4 x 10 -3 for P-4.…”

“…Thus, the water-soluble hexameric sequences 2 and 3 show g abs up to 2 × 10 −2 , which is slightly higher than sequence 5 in chloroform. Such g abs values are one order of magnitude higher in comparison to the C2-symmetric water-soluble binaphthyl fluorophores reported by Imai, 4 and it is also higher than that recently reported for a chromophoric π-extended aza [7]helicenium in an aqueous medium. 7 The chiral emission properties of the new hexamer series were further assessed in water.…”

“…Such g abs values are one order of magnitude higher in comparison to the C2-symmetric water-soluble binaphthyl fluorophores reported by Imai, 4 and it is also higher than that recently reported for a chromophoric π-extended aza [7]helicenium in an aqueous medium. 7 The chiral emission properties of the new hexamer series were further assessed in water. Irrespective of the nature of the solubilizing chains, and similar to the chiral absorption properties, a CPL response was systematically observed for the different oligomers in aqueous solution.…”

“…Such g abs values are one order of magnitude higher in comparison to the C 2-symmetric water-soluble binaphthyl fluorophores reported by Imai, 4 and it is also higher than that recently reported for a chromophoric π-extended aza[7]helicenium in an aqueous medium. 7…”

“…1 Furthermore, the circular polarization of emitted light may be used to study dynamic processes such as molecular chiral recognition. 2 However reports on effective CPL emission from chiral small organic molecules in water remain scarce, [3][4][5][6][7] limiting their potential application for biological purposes such as chiral analyte sensing or chiral bio-imaging. 8 Asymmetry in organic compounds is primarily expressed as point chirality (i.e.…”