Host–Guest Molecular Crystals of Diamino-4,4-bithiazole and Dynamic Molecular Motions via Guest Sorption

Abstract

Diamino-4,4-bithiazole (1) formed host–guest binary molecular crystals with various types of organic guest molecules including pyridine (Py), benzonitrile (PhCN), piperidine (Pipe), DMF, THF, 1,4-dioxane (Diox), CH3OH, aniline (Ani), coumarin (Coum), nitrobenzene (PhNO2), hexamethylenetetramine (HMTA), and quinoline (Quino). Single crystal X-ray structural analyses at 100 K revealed the formation of 1·(guest) or 1·(guest)2 crystals. Reversible molecular adsorption–desorption responses were observed with Py, PhCN, Pipe, DMF, and Diox around room temperature as the crystalline powders were heated during the desorption process and exposed to guest vapor during the readsorption process. The adsorption–desorption isotherms of crystalline powders 1 with Diox at 298 K indicated a reversible gate-opening adsorption–desorption process. Although the host–guest molecular crystals 1·(THF)2 and 1·(CH3OH)2 were confirmed by X-ray crystal structural analyses at 100 K, the THF and CH3OH guests were already eliminated at ...