Solvent-Induced Structural Dynamics in Noninterpenetrating Porous Coordination Polymeric Networks

Abstract

Three novel soft porous coordination polymer (PCP) or metal-organic framework (MOF) compounds have been synthesized with a new rigid ligand N-(4-pyridyl)-1,4,5,8-naphathalenetetracarboxymonoimide (PNMI) by partial hydrolysis of N,N'-di-(4-pyridyl)-1,4,5,8-naphthalenete-tracarboxydiimide (DPNI) during solvothermal reactions with Zn(II), Cd(II), and Mn(II) salts, and they are [Zn(PNMI)]·2DMA (1·2DMA, 1a), [Cd(PNMI)]·0.5DMA·5H2O (2·0.5DMA·5H2O), and [Mn(PNMI)]·0.75DMF (3·0.75DMF). The structure of 1 is based on paddle-wheel secondary building unit (SBU) with a 3,6-connected rtl net topology, whereas 2 and 3 are isotypical but the M(O2C-C)2 fragments aggregate in one-dimension and the overall connectivity is the same rtl net topology. All these three MOFs have one-dimensional rhombic channels filled with guest molecules. The guest molecules in 1a can be exchanged with EtOH in a single-crystal to single-crystal (SCSC) manner to 1·1.25EtOH·0.375H2O (1b). Further, the guest molecules in 1b can be replaced with ethylene glycol, triethylene glycol and allyl alcohol without destroying its single crystal nature. These guest exchanges are accompanied by reduction in volume of the unit cell up to 16%, as well as the void volume up to 33.1%. Similarly, triethylene glycol (TEGly) selectively exchanges EtOH in a mixture of the above solvents, which might be the result of correct fit of the hydrogen-bonded TEGly dimer in the channel of 1. While activated 1 and 3 exhibit no uptake of N2 and H2 at 1 bar and 77 K and very low uptake of CO2 gas at 1 bar and 196 K, activated 2 shows selective CO2 uptake, 278 cm(2)·g(-1), over N2 and H2 at 1 bar and 196 K, which corresponds to 5.87 molecules of CO2 per formula unit of 2.

Solvothermally derived Me2(H2O)4(5SSA)3·DMF and Me2(H2O)4(4NSA)2·DMF: Application as Biginelli reaction catalysts

“…Slightly acidic or basic solutions tend to destroy hybrid structure yielding metal salts. As was expected, methanol and ethanol tend to dissolve hybrid organic-inorganic compounds without destruction of the crystalline structure [16]. The powder X-ray diffraction analysis (see Fig.…”

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

“…Therefore, they are receiving increasing attention as they can display a wide range of interesting functional properties like dielectric [22][23][24] behavior and water sorption for heat transformation [25,26]. Furthermore, these materials can present flexible or soft porous networks, producing the third generation of porous coordination polymers [27], which are especially interesting as they can exhibit structural dynamism compared to the rigid MOFs (metal organic frameworks). This dynamic nature seems to be advantageous for the development of new materials, and can be provoked by the presence of external stimuli, as light, heat, guest removal, condensation, or reactions between the ligands.…”

Facile adaptation of 1D Mn(ii) chain motifs to form 3D azo-pyridine-based coordination polymers

“…17 The need to prepare new coordination polymers as well as to create analogues of existing structures requires the development of new synthetic techniques to enrich the diversity and complexity of coordination polymers to achieve new functions. 18 To this end, it has long been observed that various key factors, including the coordination geometry of the metal ions and the configuration and the binding mode of the organic ligands can frequently influence the self--assembly process [19][20][21][22][23][24] which is responsible for the variation in crystal packing and overall network superstructures. 25,26 Although metal coordination compounds and polymers based on conjugated bipyridine ligands such as 4,4ʹ′--azobis(pyridine) (azopy) 27,28 have been intensively studied, their implication in the deliberate synthesis of coordination polymers and modulation thereof is an attractive perspective as the resulting materials could find application in the areas such as molecular switching.…”