Quantifying the Effect of Guest Binding on Host Environment
Journal article, 2023

The environment around a host-guest complex is defined by intermolecular interactions between the complex, solvent molecules, and counterions. These interactions govern both the solubility of these complexes and the rates of reactions occurring within the host molecules and can be critical to catalytic and separation applications of host-guest systems. However, these interactions are challenging to detect using standard analytical chemistry techniques. Here, we quantify the hydration and ion pairing of a FeII4L4 coordination cage with a set of guest molecules having widely varying physicochemical properties. The impact of guest properties on host ion pairing and hydration was determined through microwave microfluidic measurements paired with principal component analysis (PCA). This analysis showed that introducing guest molecules into solution displaced counterions that were bound to the cage, and that the solvent solubility of the guest has the greatest impact on the solvent and ion-pairing dynamics surrounding the host. Specifically, we found that when we performed PCA of the measured equivalent circuit parameters and the solubility and dipole moment, we observed a high (>90%) explained variance for the first two principal components for each circuit parameter. We also observed that cage-counterion pairing is well-described by a single ion-pairing type, with a one-step reaction model independent of the type of cargo, and that the ion-pairing association constant is reduced for cargo with higher water solubility. Quantifying hydration and cage-counterion interactions is a critical step to building the next generation of design criteria for host-guest chemistries.

Author

Hugh P. Ryan

University of Cambridge

Zachary S. Fishman

National Institute of Standards and Technology (NIST)

Jacob T Pawlik

National Institute of Standards and Technology (NIST)

Angela Beth Grommet

University of Cambridge

Malgorzata Musial

National Institute of Standards and Technology (NIST)

Felix Rizzuto

University of Cambridge

James C Booth

National Institute of Standards and Technology (NIST)

Christian J Long

National Institute of Standards and Technology (NIST)

Kathleen Schwarz

National Institute of Standards and Technology (NIST)

Nathan D Orloff

National Institute of Standards and Technology (NIST)

Jonathan R. Nitschke

University of Cambridge

Angela C Stelson

National Institute of Standards and Technology (NIST)

Journal of the American Chemical Society

0002-7863 (ISSN) 1520-5126 (eISSN)

Vol. 145 36 19533-19541

Subject Categories

Physical Chemistry

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1021/jacs.3c01409

More information

Latest update

7/5/2024 7