Separation and In Situ Cocrystallization of C‑Ethylresorcin[6]arenes with 1‑(2-Pyridylazo)-2-naphthol

Macrocyclic compounds are useful in a variety of application such as gas sorption/separation as a result of their unique molecular shape and ease of synthesis. In particular, one pot synthesis of conventional resorcin­[n]­arenes (n = 4) made resorcin[4]­arenes popular for the development of novel framework materials. However, synthesis of higher resorcin­[n]­arenes (n = 5, 6) possesses difficulty in separation of a particular form from mixture of isomers and/or oligomers. This difficulty in the synthesis limits the use of higher resorcin­[n]­arene for post synthetic applications. Here, we report separation and in situ construction of novel cocrystals of C-ethylresorcin­[6]­arene separated from its tetrameric counterpart, C-ethylresorcin­[4]­arene. Structural features of three novel cocrystals of C-ethylresorcin­[6]­arene with 1-(2-pyridylazo)-2-naphthol in methanol, ethanol, and acetonitrile are discussed herein as well.