Metal Supramolecular Frameworks with Silver and Ditopic Bis(pyrazolyl)methane Ligands: Effect of the Anions and Ligand Substitution

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• 作者：Gema Dur谩 ; M. Carmen Carri贸n ; F茅lix A. Jal贸n ; Ana M. Rodr铆guez ; Blanca R. Manzano
• 刊名：Crystal Growth & Design
• 出版年：2014
• 出版时间：July 2, 2014
• 年：2014
• 卷：14
• 期：7
• 页码：3510-3529
• 全文大小：1171K
• ISSN：1528-7505

文摘

A study of the self-assembly of different silver salts and the potentially ditopic ligands bis(pyrazol-1-yl)(pyridine-4-yl)methane (L¹) and bis(3,5-dimethylpyrazol-1-yl)(pyridine-4-yl)methane (L²) was undertaken and species鈥?with discrete or polymeric structures were obtained. Reactions with L¹ always yielded derivatives that had a box-like cyclic dimer structure with two metal centers and two ligands. However, on using ligand L², the resulting structure strongly depended on the coordination ability of the anion. On using anions that have coordinating ability (X = NO₃^{鈥?/sup>, CF₃SO₃鈥?/sup>, PF₂O₂鈥?/sup>), a similar box-like structure was formed. However, the use of anions with lower coordinating ability (X = PF₆鈥?/sup>, ClO₄鈥?/sup>) led to coordination polymers with a helical disposition. Spontaneous resolution was observed in the two compounds, and only one enantiomer was present in the crystals studied. Solid-state circular dichroism spectroscopy was applied to bunches of crystals, and the results indicate that growth of single colonies of homochiral crystals starting from single nucleation points may take place. When the helical complexes were recrystallized, box-like cyclic dimers were obtained. The presence or absence of methyl groups on the pyrazolyl rings had a strong influence on the supramolecular structure. In solution, the box-like dimers containing L1 were more stable than those of L2.}