Networked-Cage Microcrystals for Evaluation of Host–Guest Interactions

We
have developed a new synthetic protocol for the preparation
of a microcrystalline powder (median size: X50 = 25 μm) of networked M6L4 cages 1a for the stationary phase of an affinity column on a greater
than 50 g scale. Analogously to large single crystals 1b (X50 ≈ 0.5 mm), microcrystals 1a 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 1a as the stationary phase. In
this way, favorable guests for networked cages 1 and
even solution M6L4 cage 2 could
easily be assessed by HPLC.