title: Computational insights into processes underlying the amine-induced fluorescence quenching of a stimuli-responsive phenol-based hexameric foldamer host.
abstract: Recently, we reported that amine-induced folding of a more fluorescent, more linear structure into less fluorescent, more curved or helically folded states enables patterned recognitions of amines and ammoniums. In this article, we have carried out extensive ab initio calculations at the B3LYP/6-31G level that not only map out the detailed amine-induced folding/quenching pathways and plausible folding/quenching species but also surprisingly reveal the binding of amines to anionic hosts to be unusually cooperative in a way that the progressively more charged anionic hosts act as increasingly better "amine trappers". Accordingly amine-dependent folding occurs via a synergistic action of amines' basicity and the progressively more curved backbone of the host. Although a hexamer carrying four deprotonable hydroxyl sites can reach a tetra-anionic state, mono-, di-, tri-, and tetra-anionic complexes likely dominate as the major quenching species in the presence of, respectively, 2, 4, 8, and 72 equiv of primary amines.
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543.
authors.forename: Chang
authors.initials: C
authors.lastname: Sun
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Jiaqiang
authors.initials: J
authors.lastname: Liu
authors.forename: Yu-Jing
authors.initials: YJ
authors.lastname: Lu
authors.forename: Lin
authors.initials: L
authors.lastname: Yu
authors.forename: Kun
authors.initials: K
authors.lastname: Zhang
authors.forename: Huaqiang
authors.initials: H
authors.lastname: Zeng