Sensing a binding event through charge transport variations using an aromatic oligoamide capsule

Abstract

Conductance through a monolayer of a helical foldamer host was found to vary by 80-fold depending on the presence or the absence of a guest in the host's cavity.

Loading Linear Arrays of CuII Inside Aromatic Amide Helices

“…Q n oligomers combine several desirable properties, including remarkably stable conformations in a variety of solvents [10] and rapid synthetic access [11] . These organic helices have been shown to be effective multidimensional charge transporters along their axis, [12] a property that may find applications in sensing [13] . Holes are transported via a hopping mechanism both through covalent bonds along the helix and through space, that is, between aromatic layers stacked within the helix.…”

“…However, it was not known whether metal binding would also alter the helical structure as is the case in related pyridinecarboxamide helices, which bind Cu II to form double helicates that are quite distinct from their single helical precursors [15] . The inner diameter of Q n helices is narrow, so much so that they are used as capping segments in the design of helical capsules [8a, 13] . Nevertheless, space suitable to fit a small metal ion might be accommodated upon amide deprotonation which would transform each Q unit into a bidentate ligand.…”

“…[11] These organic helices have been shown to be effective multidimensional charge transporters along their axis, [12] a property that may find applications in sensing. [13] Holes are transported via a hopping mechanism both through covalent bonds along the helix and through space, that is, between aromatic layers stacked within the helix. The coexistence of alternative pathways may mitigate the effect of localized traps or defects.…”

“… [15] The inner diameter of Q n helices is narrow, so much so that they are used as capping segments in the design of helical capsules. [ 8a , 13 ] Nevertheless, space suitable to fit a small metal ion might be accommodated upon amide deprotonation which would transform each Q unit into a bidentate ligand. Therefore, we endeavored to investigate metal coordination of Cu II by nitro‐ and ester‐terminated Q 2 m +1 oligomers having an odd number of units, that is, an even number of amides.…”

Loading Linear Arrays of CuII Inside Aromatic Amide Helices

“…[11] These organic helices have been shown to be effective multidimensional charge transporters along their axis, [12] a property that may find applications in sensing. [13] Holes are transported via a hopping mechanism both through covalent bonds along the helix and through space, that is, between aromatic layers stacked within the helix. The coexistence of alternative pathways may mitigate the effect of localized traps or defects.…”