Hierarchy of 蟺-Stacking Determines the Conformational Preference of Bis-Squaraines

05 October 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and 蟺-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The 蟺-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 饾浗-sheets which are determined by the hierarchy of 蟺-stacking relative to N鈥揌路路路O hydrogen bonds.

Keywords

Foldamers
Hierarchical Assembly
Bis-Squaraines
Crystal Structures
MD Simulations

Supplementary materials

Title
Description
Actions
Title
Squaramide SI1
Description
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Title
Squaramide SI2
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