A partially fluorinated ligand for two super-hydrophobic porous coordination polymers with classic structures and increased porosities

3-Ethyl-5-trifluoromethyl-1,2,4-triazole is synthesized by a one-pot reaction. Using this asymmetric triazole ligand bearing one trifluoromethyl and one ethyl as side groups, we construct two new porous coordination polymers, MAF-9 and MAF-2F, being isostructural with the classic hydrophobic and flexible materials, FMOF-1 and MAF-2, based on symmetric triazole ligands bearing two trifluoromethyl groups or two ethyl groups, respectively. MAF-9 and MAF-2F can adsorb large amounts of organic solvents but completely exclude water, showing superhydrophobicity with water contact angles of 152o in between those of FMOF-1 and MAF-2. MAF-9 exhibits very large N2-induced breathing and colossal positive and negative thermal expansions like FMOF-1, but the lower molecular weight and smaller volume of MAF-9 give 16% and 4% higher gravimetric and volumetric N2 uptakes, respectively. In contrast, MAF-2F is quite rigid and does not show the inversed temperature-dependent N2 adsorption and large guest-induced expansion like MAF-2. Further, despite the higher molecular weight and larger volume, MAF-2F possesses 6% and 25% higher gravimetric and volumetric CO2 uptakes, respectively. These results can be explained by the different pore sizes and side group arrangements in the two classic framework prototypes, which demonstrate the delicate roles of ligand side groups in controlling porosity, surface characteristic and flexibility.

One-pot concomitant preparation of two copper(II) coordination polymers with different configurations of bridging bithiophene ligands

By employing the conjugated bithiophene ligand 5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene (bibp), which can exhibit trans and cis conformations, two different Cu^II coordination polymers, namely, poly[[μ-5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene-κ²N:N'](μ₂-4,4'-oxydibenzoato-κ²O:O')copper(II)], [Cu(C₁₄H₈O₅)(C₁₄H₁₀N₄S₂)]_n or [Cu(bibp)(oba)]_n, (I), and catena-poly[μ-aqua-bis[μ-5,5'-bis(1H-imidazol-1-yl)-2,2'-bithiophene-κ²N:N']bis(μ₃-4,4'-oxydibenzoato)-κ³O:O':O'';κ⁴O:O',O'':O'-dicopper(II)], [Cu₂(C₁₄H₈O₅)₂(C₁₄H₁₀N₄S₂)(H₂O)]_n or [Cu₂(bibp)(oba)₂(H₂O)]_n, (II), have been prepared through one-pot concomitant crystallization and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental analysis, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analysis. Single-crystal X-ray diffraction indicates that the most interesting aspect of the structure is the existence of sole trans and cis conformations of the bibp ligand in a single net of (I) and (II), respectively. Compound (I) displays a threefold interpenetrating three-dimensional framework with a 4-connected {6⁵.8} cds topology, whereas (II) features a one-dimensional chain structure. In the crystal of (II), the polymeric chains are further extended through C-H...O hydrogen bonds and C-H...π interactions into a three-dimensional supramolecular architecture. In addition, strong intramolecular O-H...O hydrogen bonds formed between the bridging water molecules and the carboxylate O atoms improve the stability of the framework of (II). Furthermore, solid-state UV-Vis spectroscopy experiments show that compounds (I) and (II) exhibit optical band gaps which are characteristic for optical semiconductors, with values of 2.70 and 2.26 eV, respectively.

Solvent effects on the crystal structure of silver pentacyanocyclopentadienide: supramolecular isomerism and solvent coordination

Several coordination polymers of silver(i)-pentacyanocyclopentadienide (PCC) were studied by X-ray diffraction to examine the effects of different solvents on supramolecular isomerism of the PCC-ligand. While alcohols yield supramolecular isomers of [Ag(PCC)] without coordination of solvent molecules, less polar solvents show coordinate binding. The influence of solvent polarity can be observed by a gradual change in the lattice structure featuring distinct motifs.

Solvent-induced construction of two zinc supramolecular isomers: synthesis, framework flexibility, sensing properties, and adsorption of dye molecules

Solvent-induced construction of two zinc supramolecular isomerism, sensing properties and adsorption of dye molecules.