title: Three polymorphs of an inclusion compound of 2,2'-(disulfanediyl)dibenzoic acid and trimethylamine.
abstract: Polymorphism is the ability of a solid material to exist in more than one form or crystal structure and this is of interest in the fields of crystal engineering and solid-state chemistry. 2,2'-(Disulfanediyl)dibenzoic acid (also called 2,2'-dithiosalicylic acid, DTSA) is able to form different hydrogen bonds using its carboxyl groups. The central bridging S atoms allow the two terminal arene rings to rotate freely to generate various hydrogen-bonded linking modes. DTSA can act as a potential host molecule with suitable guest molecules to develop new inclusion compounds. We report here the crystal structures of three new polymorphs of the inclusion compound of DTSA and trimethylamine, namely trimethylazanium 2-[(2-carboxyphenyl)disulfanyl]benzoate 2,2'-(disulfanediyl)dibenzoic acid monosolvate, C3H10N+·C14H9O4S2-·C14H10O4S2, (1), tetrakis(trimethylazanium) bis{2-[(2-carboxyphenyl)disulfanyl]benzoate} 2,2'-(disulfanediyl)dibenzoate 2,2'-(disulfanediyl)dibenzoic acid monosolvate, 4C3H10N+·2C14H9O4S2-·C14H8O4S22-·C14H10O4S2, (2), and trimethylazanium 2-[(2-carboxyphenyl)disulfanyl]benzoate, C3H10N+·C14H9O4S2-, (3). In the three polymorphs, DTSA utilizes its carboxyl groups to form conventional O-H...O hydrogen bonds to generate different host lattices. The central N atoms of the guest amine molecules accept H atoms from DTSA molecules to give the corresponding cations, which act as counter-ions to produce the stable crystal structures via N-H...O hydrogen bonding between the host acid and the guest molecule. It is noticeable that although these three compounds are composed of the same components, the final crystal structures are totally different due to the various configurations of the host acid, the number of guest molecules and the inducer (i.e. ancillary experimental acid).
authors.affiliation: Key Laboratory of Polymer Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, Gansu, People's Republic of China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Polymer Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, Gansu, People's Republic of China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Polymer Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, Gansu, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Polymer Materials of Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, Gansu, People's Republic of China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Dong
authors.affiliation: Chemistry Department, Middle Tennessee State University, Murfreesboro 37130, USA.
authors.forename: Keying
authors.initials: K
authors.lastname: Ding
keywords: 2,2′-dithiosalicylic acid; crystal engineering; crystal structure; hydrogen bonding; inclusion compounds; polymorphs; solid-state chemistry