Artificial Organic Host Molecules for Anions

A series of shape-persistent [34]triazolophanes bearing t-butyl or triethylene glycol (OTg) substituents on the phenylene linkers have been prepared in a modular manner from simple building blocks. Triazolophane−halide binding affinities were determined using UV titrations in order to help in understanding the driving forces behind the large receptor−anion binding strengths supported solely by CH hydrogen-bond donors. The fixed size of the central cavity provides a means for selective recognition of Cl− and Br− anions with large binding strengths (Ka > 1 000 000 M−1; ΔG > −8.5 kcal mol−1). The smaller F− and larger I− anions are bound less tightly by ∼1 and ∼3 orders of magnitude, respectively. The four triazole-based H-bond donors are believed to be of primary importance, while the four phenylene CH H-bond donors take on a secondary role. Consistent with this idea, the binding affinity can be tuned by as much as 1 kcal mol−1 by changing the character of the four phenylene-based substituents from more (OT...

Strong, size-selective, and electronically tunable C-H...halide binding with steric control over aggregation from synthetically modular, shape-persistent [34]triazolophanes.

Takashi. Yatsunami

Papers

Identification of macrocyclic polyamines and macrocyclic dioxopolyamines by thin-layer chromatography, gas chromatography, and electrophoresis