Networked-Cage Microcrystals for Evaluation of Host–Guest Interactions

Abstract

We have developed a new synthetic protocol for the preparation of a microcrystalline powder (median size: <i>X</i>₅₀ = 25 μm) of networked M₆L₄ cages <b>1a</b> for the stationary phase of an affinity column on a greater than 50 g scale. Analogously to large single crystals <b>1b</b> (<i>X</i>₅₀ ≈ 0.5 mm), microcrystals <b>1a</b> accommodate guest molecules tetrathiafulvalene (TTF) and fullerene (C₆₀) at up to 32 and 35 wt %, respectively. Importantly, the host–guest interactions within networked cages could be evaluated in terms of the retention time from HPLC analysis by using microcrystals <b>1a</b> as the stationary phase. In this way, favorable guests for networked cages <b>1</b> and even solution M₆L₄ cage <b>2</b> could easily be assessed by HPLC