Monotropic Polymorphism in Copper(II) Decanoate

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• 作者：M. Ramos Riesco ; F. J. Marti&#x301 ; nez Casado ; S. Lo&#x301 ; pez-Andre&#x301 ; s ; M. V. Garci&#x301 ; a Pe&#x301 ; rez ; M. I. Redondo Ye&#x301 ; lamos ; M. R. Torres ; L. Garrido ; J. A. Rodri&#x301 ; guez Cheda
• 刊名：Crystal Growth & Design
• 出版年：2008
• 出版时间：July 2008
• 年：2008
• 卷：8
• 期：7
• 页码：2547 - 2554
• 全文大小：971K
• 年卷期：v.8,no.7(July 2008)
• ISSN：1528-7505

文摘

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 single-crystal 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; α = 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; α = 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, P1ace="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̅. 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.