Solid-state structural studies of oxacalix[2]arene[2]naphthalene as a molecular tweezer

Abstract

A novel oxacalix[2]arene[2]naphthalene host molecule was synthesized and crystallized from a number of solvents. In the solid state the host assumes the 1,3-alternate conformation, allowing it to function as a molecular tweezer by utilizing its naphthalene moieties as pincer arms. An apohost phase was crystallized from DMSO and single-crystal X-ray diffraction analysis reveals that the pincer arms are pinched together rather than interdigitating. Solvate crystals were obtained from dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidone and nitrobenzene and these were also analyzed by means of single-crystal X-ray diffraction. Three of the solvate phases are isoskeletal with a host : guest ratio of 1 : 1, and with the guest molecules located between the pincer arms. The nitrobenzene solvate has a host : guest ratio of 1 : 2—one of the guest molecules is complexed by the pincer arms while the second is situated interstitially.