title: Crystal structures and spectroscopic properties of ester amide and diamide of squaric acid with prolinamide.
abstract: We report the synthesis, spectroscopic and structural elucidation of two prolinamide derivatives of squaric acid, i.e. prolinamide ester amide of squaric acid ethyl ester (1) and prolinamide diamide of squaric acid dihydrate (2). Both compounds crystallize in non-centrosymmetric space groups, monoclinic P2(1) (1) and orthorhombic P2(1)2(1)2(1) (2), respectively. For first time in the literature the crystal structure of homodiamide of amino acid amide of squaric acid is reported. The data for heterodiamides is also absent. Supramolecular zig-zag chains by hydrogen bonds of H(2)N-C=O ..., HNH (3.020 A) and HNH ..., OC((S(q))) (2.972 A) types with the participation of amide and squaric acid (S(q)) fragments, -CO=NH(2) and O=C((S(q))) are refined in (1). A helix supramolecular structure is formed in (2) by moderate intermolecular HNH ... O=C(NH(2)) hydrogen bond with length of 2.947A. The two crystallographical non-equivalent water molecules stabilized the helix by interactions of types HOH...OC((Sq)) (2.917A), HOH...O=C(NH(2)) (2.899A), H(2)O...NH(2)(C=O) (2.972A), respectively. Optical and magnetic properties are investigated with a view to explain the correlation structure-properties of the newly synthesized molecules.
authors.affiliation: Institut für Umweltforschung, Universityat Dortmund, Otto-Hahn-Strasse 6, 44221 Dortmund, Germany.
authors.forename: Tsonko
authors.initials: T
authors.lastname: Kolev
authors.forename: Rüdiger W
authors.initials: RW
authors.lastname: Seidel
authors.forename: Heike
authors.initials: H
authors.lastname: Mayer-Figge
authors.forename: Michael
authors.initials: M
authors.lastname: Spiteller
authors.forename: William S
authors.initials: WS
authors.lastname: Sheldrick
authors.forename: Bojidarka B
authors.initials: BB
authors.lastname: Koleva
mesh_terms: D002152:Calorimetry, Differential Scanning; D002851:Chromatography, High Pressure Liquid; D003461:Crystallography; D003503:Cyclobutanes / Q000737:chemistry*; D003958:Diamide / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D008970:Molecular Weight; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013055:Spectrophotometry, Infrared; D053719:Tandem Mass Spectrometry; D013818:Thermogravimetry; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D003503:Cyclobutanes; D004952:Esters; D014867:Water; D003958:Diamide; D011392:Proline; C030042:squaric acid; C056291:prolinamide