Guest Binding Drives Host Redistribution in Libraries of CoII 4 L4 Cages.

Marion Kieffer,John D Thoburn,Rana A Bilbeisi,Jonathan R Nitschke,Jack K Clegg

doi:10.1002/anie.202004627

Abstract

Two CoII 4L4 tetrahedral cages prepared from similar building blocks showed contrasting host–guest properties. One cage did not bind guests, whereas the second encapsulated a series of anions, due to electronic and geometric effects. When the building blocks of both cages were present during self‐assembly, a library of five CoII LA x LB 4−x cages was formed in a statistical ratio in the absence of guests. Upon incorporation of anions able to interact preferentially with some library members, the products obtained were redistributed in favor of the best anion binders. To quantify the magnitudes of these templation effects, ESI‐MS was used to gauge the effect of each template upon library redistribution.

Highlights

Two CoII4L4 tetrahedral cages prepared from similar building blocks showed contrasting host–guest properties
The outcome of self-sorting[8] in dynamic libraries can be influenced by the addition of new components to libraries,[9] which interact preferentially with certain library members.[10]
Mass spectrometry has proven to be a useful technique to quantify templation effects on these systems,[11] which could allow for better understanding of the binding processes that induce molecular reconfiguration

Summary

Introduction

Two CoII4L4 tetrahedral cages prepared from similar building blocks showed contrasting host–guest properties. BrÀ, IÀ, BF4À, and ClO4À anions, as well as acetonitrile, were found to bind within 2 (see Supporting Information section 4.2). (6 equiv) and Co(NTf2)2 (2 equiv) in CH3CN led to the formation of a library of cages (LibNTf2 ) as confirmed by ESIMS and 1H NMR (Figures 2 a and b, S33 and S34).

Results

Conclusion