Cu-PDC-bpa solid coordination frameworks (PDC=2,5-pyrindinedicarboxylate; bpa=1,2-DI(4-pyridil)ethane)): 2D and 3D structural flexibility producing a 3-c herringbone array next to ideal

• Published in: Journal of solid state chemistry Vol. 230; pp. 191 - 198
• Main Authors: Llano-Tomé, Francisco, Bazán, Begoña, Urtiaga, Miren-Karmele, Barandika, Gotzone, Antonia Señarís-Rodríguez, M., Sánchez-Andújar, Manuel, Arriortua, María-Isabel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-10-2015
• Subjects: ABSORPTION SPECTROSCOPY; ANIONS; COPPER COMPOUNDS; CRYSTAL STRUCTURE; Crystal structures; Crystalline to-amorphous to-crystalline transformation; DIELECTRIC MATERIALS; DIELECTRIC PROPERTIES; DIFFERENTIAL THERMAL ANALYSIS; ETHANE; Herringbone-type layers; HYDRATES; HYDROGEN; INFRARED SPECTRA; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LAYERS; LIGANDS; MOBILITY; PHASE TRANSFORMATIONS; Solid coordination frameworks; SOLVENTS; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION; Crystal structures; Herringbone-type layers; Solid coordination frameworks; Crystalline to-amorphous to-crystalline transformation; Dielectric properties
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2015.06.039

Combination of polycarboxylate anions and dipyridyl ligands is an effective strategy to produce solid coordination frameworks (SCF) which are crystalline materials based on connections between metal ions through organic ligands. In this context, this work is focused on two novel CuII-based SCFs exhibiting PDC (2,5-pyridinedicarboxylate) and bpa (1,2-di(4-pyridyl)ethane), being the first structures reported in literature containing both ligands. Chemical formula are [Cu2[(PDC)2(bpa)(H2O)2]·3H2O·DMF (1), and [Cu2(PDC)2(bpa)(H2O)2]·7H2O (2), where DMF is dimethylformamide. Compounds 1 and 2 have been characterized by means of X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric (TG) analysis, differential thermal analysis (DTA) and dielectric measurements. The crystallographic analysis revealed that compounds 1 and 2 can be described as herringbone-type layers formed by helicoidal Cu-PDC-Cu chains connected through bpa ligands. Solvent molecules are crystallized between the layers, providing the inter-layer connections through hydrogen bonds. Differences between both compounds are attributable to the flexibility of bpa (in 2D) as well as to the 3D packing of the layers which is solvent dependent. This fact results in the fact that compound 2 is the most regular 3-c herringbone array reported so far. The structural dynamism of these networks is responsible for the crystalline to-amorphous to-crystalline (CAC) transformation from compound 1 to compound 2. Crystallochemical features for both compounds have also been studied and compared to similar 3-connected herringbone-arrays.
Cu-PDC-bpa 3-c herringbone arrays.
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•The most ideal herringbone array reported so far is a Cu-PDC-bpa SCF.•Conformational freedom of bpa results in 2D and 3D flexibility of the SCFs.•The flexibility of the SCFs is related to a phase transformation.•Dielectric measurements confirm the mobility of guest solvent molecules.