posted on 2021-07-31, 00:43authored byTiezheng Pan, Jiangbo Li, Bo Li, Qiangqiang Xu, Zhiliyu Cui, Jie Shang, Yan Ge, Zhenhui Qi
Supramolecular assemblies based on
oligo(ethylene glycol) (OEG)
building blocks are well-known for their neutral chemical property
and thermal-responsive behavior. Here, the cyclic “CLOSED”
and linear “OPEN” typologies of OEGs led to dramatic
difference in the sensitivity to guanidinium-containing species. From
thermodynamic studies, the association constant (Ka) between the “CLOSED” form amphiphile
and guanidinium salt was determined to be 28.7 M–1, whereas there was no detectable binding affinity for the “OPEN”
form. Therefore, considering ion specificity, the present results
establish that crown ether derivatives with “CLOSED”
and “OPEN” topologies provide an easy-to-access model
pair with designed ion-recognition sites and special functional moieties
and geometries (like the binding pockets of enzymes or ion channels
in cellular members) that allow the manipulation of the intercrossed
relationship between supramolecular solutes, waters, and guanidinium
salts. These supramolecular forces in aqueous solution offered an
alternative strategy to fabricate thermal-responsive systems in ionic
medium.