title: One- and two-dimensional polymers from proline and calcium bromide.
abstract: Reactions of calcium bromide with enantiopure and racemic proline in aqueous solution lead to two solids in which the zwitterionic amino acid acts as a bridging ligand between neighbouring cations. Depending on the chirality of the amino acid, topologically very different products are obtained. With racemic proline, bromide acts as a simple uncoordinated counter-anion for the cationic heterochiral chains in catena-poly[[aquacalcium(II)]-μ-aqua-μ3-DL-proline-μ2-DL-proline], {[Ca(C5H9NO2)2(H2O)2]Br2}n. In agreement with chemical intuition, only carboxylate and aqua O atoms coordinate the alkaline earth cation in a low-symmetry arrangement. In contrast, L-proline affords the two-dimensional network poly[dibromidobis(μ2-L-proline)calcium(II)], [CaBr2(C5H9NO2)2]n, with an unexpected CaBr2 unit in a more regular coordination sphere.
authors.affiliation: Institut für Anorganische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Lamberts
authors.affiliation: Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, Polizu 1, RO-011061 Bucharest, Romania.
authors.forename: Mihaela-Diana
authors.initials: MD
authors.lastname: Şerb
authors.affiliation: Institut für Anorganische Chemie, RWTH Aachen, Landoltweg 1, 52074 Aachen, Germany.
authors.forename: Ulli
authors.initials: U
authors.lastname: Englert
mesh_terms: D001965:Bromides / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001965:Bromides; D017610:Calcium Compounds; D056831:Coordination Complexes; D011108:Polymers; C113019:calcium bromide; D011392:Proline
keywords: bridging ligands; calcium bromide; calcium polymer; chirality; crystal structure; one-dimensional coordination polymer; racemic compounds; two-dimensional network; zwitterionic proline