Anion–π interaction has been found to play a kye role in interfacial phenomena. In this study, we evaluated the anion–π interactions at the solid/water interface. Anion adsorption originating from anion–π...
Biological systems precisely and selectively control
ion binding
through various chemical reactions, molecular recognition, and transport
by virtue of effective molecular interactions with biological membranes
and proteins. Because ion binding is inhibited in highly polar media,
recognition systems for anions in aqueous media, which are relevant
to biological and environmental systems, are still limited. In this
study, we explored the anion binding of Langmuir monolayers formed
by amphiphilic naphthalenediimide (NDI) derivatives with a series
of substituents at air/water interfaces via anion−π interactions.
Density functional theory (DFT) simulations revealed that the binding
of anions originating from anion−π interactions is related
to the electron density of the anions. At the air/water interfaces,
amphiphilic NDI derivatives formed Langmuir monolayers, and the addition
of anions caused expansion of the Langmuir monolayers. The anions
with larger hydration energies related to electron density showed
larger binding constants (K
a) for 1:1
stoichiometry with the NDI derivatives. The loosely packed monolayer
formed by the amphiphilic NDI derivatives with bromine groups showed
a better anion response. In contrast, the binding of NO3
– was significantly enhanced in the highly packed
monolayer. These results indicate that the packing of NDI derivatives
with rigid aromatic rings influenced the binding of the anions. These
results provide insight into ion binding using the air/water interface
as a promising recognition site for mimicking biological membranes.
In future, sensing devices can be developed using Langmuir–Blodgett
films on electrodes. Furthermore, the capture of anions on electron-deficient
aromatic compounds can lead to doping or composition technologies
for n-type semiconductors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.