4-Phenoxyphenol: A Porous Molecular Material

4-Phenoxyphenol is a simple organic molecule that crystallizes as a porous material with channels running throughout the structure. The channels are constructed by a 6-fold hydrogen bonded ring and can host solvent molecules incorporated during crystal growth, with a minimum channel diameter of 5.8–5.9 Å; each channel usually contains a single solvent molecule per unit cell. The hydrogen bonded ring shows surprising flexibility, being able both to breathe and to sustain its crystalline integrity even when grown with empty pores. This is particularly surprising given that the remainder of the interactions within the crystal structure are C–H···π interactions and are weak in nature. It is also possible to grow “dry” porous 4-phenoxyphenol crystals by using a bulky solvent in the recrystallization.