Halogen Trimer-Mediated Hexagonal Host Framework of 2,4,6-Tris(4-halophenoxy)-1,3,5-triazine. Supramolecular Isomerism from Hexagonal Channel (X = Cl, Br) to Cage Structure (X = I)

The hexagonal layer structure of host atoms in chloro, bromo, and iodo derivatives of 2,4,6-tris(4-halophenoxy)-1,3,5-triazine, X-POT, is stabilized by a cyclic and cooperative halogen trimer (X···X) synthon. The X···X distance is ∼3.5 A in isostructural channel inclusion adducts of Cl-POT and Br-POT, whereas I···I is ∼3.8 A in cage structures of I-POT with aromatic and hydrophobic guests. X-ray crystal structures of I-POT with mesitylene, collidine, tribromomesitylene, triiodomesitylene, hexachlorobenzene, hexafluorobenzene, 1-methylnaphthalene, CH2Cl2, CH2Br2, and CH2I2 guests in R3 space group are reported. Host molecules are fully ordered in these isostructural clathrates, whereas guest atoms are disordered except for C6Cl6 and C6F6. The guest molecule resides in a penta-decker sandwich surrounded by double layers of iodo trimer and triazine ring. Supramolecular isomerism from channel to cage framework and the persistent crystallization of trigonal X-POT molecules in high-symmetry host networks (spac...