Monotropic polymorphism in Copper(II) Decanoate
Copper(II) decanoate was synthesized, purified and studied by DSC, optical microscopy, XRD, and FTIR and C-13 NMR spectroscopies. Depending on the solvent used for crystallization two polymorphs were obtained. A combination of singlecrystal and powder XRD was used to study their structures. One of t...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2008 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/88150 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/88150 |
| Access Level: | acceso abierto |
| Palabra clave: | 548 Copper (II) Polymorphism Crystal Cristalografía (Geología) 2211.04 Cristalografía |
| Sumario: | Copper(II) decanoate was synthesized, purified and studied by DSC, optical microscopy, XRD, and FTIR and C-13 NMR spectroscopies. Depending on the solvent used for crystallization two polymorphs were obtained. A combination of singlecrystal and powder XRD was used to study their structures. One of the polymorphs (recrystallized in n-heptane) has similar structure to that previously reported at room temperature: triclinic (a ) 7.94(1) Å, b ) 5.28(3) Å, c ) 28.13(5) Å; R ) 94.6(10)°, β = 97.1(5)°, γ ) 98.6(10)°). A single crystal of the second polymorph was obtained from an ethanol solution and has a triclinic structure (a ) 5.2035(1) Å, b ) 14.331(3) Å, c ) 16.440(4) Å; R ) 65.390(4)°, β = 86.889(4)°, γ ) 82.886(4)°). This polymorph is monotropic and was identified by calorimetry as the metastable form. Both room temperature crystalline polymorphs belong to the same space group, P1j . However, they differ in (1) unit cell parameters; (2) one is bilayered whereas the other presents a columnar distribution of the binuclear complexes inside a net of two-by-two interdigitated chains. Thermal coefficients for both polymorphs have been estimated by indexation of their powder X-ray patterns versus temperature. The FTIR and C-13 NMR techniques confirm the structural differences. Both polymorphs melt to the same columnar discotic liquid crystal (identified by optical microscopy), decomposing before reaching the clearing point. |
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