Synthesis, Crystal Structure and Fluorescence of Two Novel Mixed-Ligand Cadmium Coordination Polymers with Different Structural Motifs

Large Differences in Carbon Dioxide and Water Sorption Capabilities in a System of Closely Related Isoreticular Cd(II)-based Mixed-Ligand Metal-Organic Frameworks

We report the synthesis of two isoreticular, mixed-ligand metal-organic frameworks (MOFs), [Cd(μ₂-mia)(μ₂-bpe)]_n·n(DMF)_0.5·n(H₂O)_0.5 (1) and [Cd(μ₂-nia)(μ₂-bpee)]_n·nDMF (2), where mia = 5-methoxyisophthalate, nia = 5-nitroisophthalate, bpe = 1,2-bis(4-pyridyl)ethane, bpee = 1,2-bis(4-pyridyl)ethylene, and DMF = N,N'-dimethylformamide. Variable-temperature powder X-ray diffraction studies confirmed that both MOFs remain crystalline with activation at high temperatures. Variable-temperature single-crystal X-ray diffraction studies were performed on 1, 2, and a previously published, isoreticular structure, [Cd(μ₂-nia)(μ₂-bpe)_1.5]_n·nDMF_0.84 (3). These studies show that upon desolvation that monocrystallinity is retained to significantly higher temperatures for 2 and 3 when compared to 1 for which only a partially desolvated crystal structure could be obtained. Carbon dioxide sorption is negligible for 1 at 195 and 298 K, while it is higher for 2 than 3 at 298 K and reversed at 195 K. Water vapor sorption increases in the order 1, 2, and 3. On the contrary, water liquid sorption was significantly higher for 1 when compared to 2. The variable-temperature structures of the (partially) desolvated forms of 1, 2, and 3 give some insight into the reasons for the remarkably different gas, vapor, and liquid sorption properties.

Syntheses, structural diversities and characterization of a series of coordination polymers with two isomeric oxadiazol-pyridine ligands

In this work two positional-isomeric oxadiazol-pyridine ligands 3-(5-methyl-1,3,4-oxadiazol-2-yl)pyridine (L₁) and 4-(5-methyl-1,3,4-oxadiazol-2-yl)pyridine (L₂) have been designed and synthesized.

Flexible and asymmetric ligand in constructing coordinated complexes: synthesis, crystal structures and fluorescent characterization

Flexible and asymmetric ligand L [L = 1-((pyridin-3-yl)methyl)-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag₂(L)₂(NO₃)₂]_n (1) and [Ag(L)(ClO₄)]_n (2), were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology.