Tetrakis(dimethoxyphenyl)adamantane (TDA) and Its Inclusion Complexes in the Crystalline State: A Versatile Carrier for Small Molecules

Molecular storage solutions for incorporating small molecules in crystalline matrices are of interest in the context of structure elucidation, decontamination, and slow release of active ingredients. Here we report the syntheses of 1,3,5,7‐tetrakis(2,4‐dimethoxyphenyl)adamantane, 1,3,5,7‐tetrakis(4‐methoxyphenyl)adamantane, 1,3,5,7‐tetrakis(4‐methoxy‐2‐methylphenyl)adamantane, and 1,3,5,7‐tetrakis(4‐methoxy‐2‐ethylphenyl)adamantane, together with their X‐ray crystal structures. All four compounds crystallize readily. Only the octaether shows an unusual level of (pseudo)polymorphism in its crystalline state, combined with the ability to include a number of different small molecules in its crystal lattices. A total of 20 different inclusion complexes with guest molecules as different as ethanol or trifluorobenzene were found. For nitromethane and benzene, schemes for uptake and release are presented. Selective inclusion: A tetraaryladamantane octaether was shown to form 20 different inclusion complexes, absorbing toxic compounds such as benzene selectively, and releasing guests such as nitromethane upon recrystallizing from alcohols.