Efficient Purification of 2,6-Lutidine by Nonporous Adaptive Crystals of Pillararenes.

2,6-Lutidine () is a very important raw material in the chemical industry, but the impurities of 3-picoline () and 4-picoline () existing in seriously affect its quality. Considering different molecular sizes of these three compounds, herein, we exploit nonporous adaptive crystals (NACs) of pillararenes as purifying agents for removal of and in . We find that -ethylated pillar[5]arene () can selectively adsorb and , while negligible capture of is observed, resulting in improvement of the purity of up to 94.9%. Single-crystal structures indicate that the excellent selectivity originates from the size match and complexation stability differences among different host/guest pairs. After purification, NACs of can be easily regenerated and used in the next run without a significant performance degradation.