Solid state forms of 4-aminoquinaldine – from void structures with and without solvent inclusion to close packing. Issue 12 (25th February 2015)

• Record Type: Journal Article
• Authors: Braun, Doris E.; Gelbrich, Thomas; Kahlenberg, Volker; Griesser, Ulrich J.
• Is Part Of: CrystEngComm. Volume 17:Issue 12(2015)
• Page Start: 2504
• Page End: 2516
• Publication Date: 2015-02-25
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/c5ce00118h
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : Crystal structure prediction combined with experimental studies unveil the structural and thermodynamic features of three non-solvated forms and a carbon tetrachloride solvate of 4-aminoquinaldine and provide intriguing insights into void structures and the role of solvent inclusion. Abstract : Polymorphs of 4-aminoquinaldine (4-AQ ) have been predicted in silico and experimentally identified and characterised. The two metastable forms, AH (anhydrate)II andAH III, crystallise in the trigonal space group R 3̄ and are less densely packed than the thermodynamically most stable phaseAH I° ( P 21 / c ).AH II can crystallise and exist both, as a solvent inclusion compound and as an unsolvated phase. The third polymorph, AH III, is exclusively obtained by desolvation of a carbon tetrachloride solvate. Theoretical calculations correctly estimated the experimental 0 K stability order, confirmed thatAH II can exist without solvents, gave access to theAH III structure, and identified that there exists a subtle balance between close packing and number of hydrogen bonding interactions in the solid state of anhydrous4-AQ . Furthermore, the prevalence of void space and solvent inclusion in R 3̄ structures is discussed.