Influential factors on assembly of first-row transition metal coordination polymers

Chromium(II)-isophthalate 2D MOF with Redox-Tailorable Gas Adsorption Selectivity

Redox-active metal-organic frameworks (MOFs) are very promising materials due to their potential capabilities for postsynthetic modification aimed at tailoring their application properties. However, the research field related to redox-active MOFs is still relatively underdeveloped, which limits their practical application. We investigated the self-assembly process of Cr(II) ions and isophthalate (m-bdc) linkers, which have been previously demonstrated to yield 0D metal-organic polyhedra. However, using the diffusion-controlled synthetic approach, we demonstrate the selective preparation of a 2D-layered Cr(II)-based MOF material [Cr(m-bdc)]·H2O (1·H2O). Remarkably, the controlled oxidation of the developed 2D MOF using nitric oxide or dry oxygen resulted in modified porous materials with excellent H2/N2 adsorption selectivities.

A Series of Metal-Organic Frameworks with 2,2'-Bipyridyl Derivatives: Synthesis vs. Structure Relationships, Adsorption, and Magnetic Studies

Five new metal-organic frameworks based on Mn(II) and 2,2'-bithiophen-5,5'-dicarboxylate (btdc^2-) with various chelating N-donor ligands (2,2'-bipyridyl = bpy; 5,5'-dimethyl-2,2'-bipyridyl = 5,5'-dmbpy; 4,4'-dimethyl-2,2'-bipyridyl = 4,4'-dmbpy) [Mn₃(btdc)₃(bpy)₂]·4DMF, 1; [Mn₃(btdc)₃(5,5'-dmbpy)₂]·5DMF, 2; [Mn(btdc)(4,4;-dmbpy)], 3; [Mn₂(btdc)₂(bpy)(dmf)]·0.5DMF, 4; [Mn₂(btdc)₂(5,5'-dmbpy)(dmf)]·DMF, 5 (dmf, DMF = N,N-dimethylformamide) have been synthesized, and their crystal structure has been established using single-crystal X-ray diffraction analysis (XRD). The chemical and phase purities of Compounds 1-3 have been confirmed via powder X-ray diffraction, thermogravimetric, and chemical analyses as well as IR spectroscopy. The influence of the bulkiness of the chelating N-donor ligand on the dimensionality and structure of the coordination polymer has been analyzed, and the decrease in the framework dimensionality, as well as the secondary building unit's nuclearity and connectivity, has been observed for bulkier ligands. For three-dimensional (3D) coordination polymer 1, the textural and gas adsorption properties have been studied, revealing noticeable ideal adsorbed solution theory (IAST) CO₂/N₂ and CO₂/CO selectivity factors (31.0 at 273 K and 19.1 at 298 K and 25.7 at 273 K and 17.0 at 298 K, respectively, for the equimolar composition and the total pressure of 1 bar). Moreover, significant adsorption selectivity for binary C₂-C₁ hydrocarbons mixtures (33.4 and 24.9 for C₂H₆/CH₄, 24.8 and 17.7 for C₂H₄/CH₄, 29.3 and 19.1 for C₂H₂/CH₄ at 273 K and 298 K, respectively, for the equimolar composition and the total pressure of 1 bar) has been observed, making it possible to separate on 1 natural, shale, and associated petroleum gas into valuable individual components. The ability of Compound 1 to separate benzene and cyclohexane in a vapor phase has also been analyzed based on the adsorption isotherms of individual components measured at 298 K. The preferable adsorption of C₆H₆ over C₆H₁₂ by 1 at high vapor pressures (V_B/V_CH = 1.36) can be explained by the existence of multiple van der Waals interactions between guest benzene molecules and the metal-organic host revealed by the XRD analysis of 1 immersed in pure benzene for several days (1≅2C₆H₆). Interestingly, at low vapor pressures, an inversed behavior of 1 with preferable adsorption of C₆H₁₂ over C₆H₆ (K_CH/K_B = 6.33) was observed; this is a very rare phenomenon. Moreover, magnetic properties (the temperature-dependent molar magnetic susceptibility, χ_p(T) and effective magnetic moments, μ_eff(T), as well as the field-dependent magnetization, M(H)) have been studied for Compounds 1-3, revealing paramagnetic behavior consistent with their crystal structure.

Crystal structure of poly[(N,N-dimethylacetamide-κO) (μ4-2-nitroisophthalato-κ 4 O:O′:O″:O′″)manganese(II)], C11H10N2O7Mn

C11H10N2O7Mn, monoclinic, P21/c (no. 14), a = 8.1501(5) Å, b = 10.8198(7) Å, c = 15.2391(9) Å, β = 91.921(5)°, V = 1343.07(14) Å3, Z = 4, R gt(F) = 0.0363, wRref (F 2) = 0.0783, T = 293 K.

3D Metal-Organic Frameworks Based on Co(II) and Bithiophendicarboxylate: Synthesis, Crystal Structures, Gas Adsorption, and Magnetic Properties

Three new 3D metal-organic porous frameworks based on Co(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc²⁻) [Co₃(btdc)₃(bpy)₂]·4DMF, 1; [Co₃(btdc)₃(pz)(dmf)₂]·4DMF·1.5H₂O, 2; [Co₃(btdc)₃(dmf)₄]∙2DMF∙2H₂O, 3 (bpy = 2,2′-bipyridyl, pz = pyrazine, dmf = N,N-dimethylformamide) were synthesized and structurally characterized. All compounds share the same trinuclear carboxylate building units {Co₃(RCOO)₆}, connected either by btdc^2– ligands (1, 3) or by both btdc^2– and pz bridging ligands (2). The permanent porosity of 1 was confirmed by N₂, O₂, CO, CO₂, CH₄ adsorption measurements at various temperatures (77 K, 273 K, 298 K), resulted in BET surface area 667 m²⋅g⁻¹ and promising gas separation performance with selectivity factors up to 35.7 for CO₂/N₂, 45.4 for CO₂/O₂, 20.8 for CO₂/CO, and 4.8 for CO₂/CH₄. The molar magnetic susceptibilities χ_p(T) were measured for 1 and 2 in the temperature range 1.77–330 K at magnetic fields up to 10 kOe. The room-temperature values of the effective magnetic moments for compounds 1 and 2 are μ_eff (300 K) ≈ 4.93 μ_B. The obtained results confirm the mainly paramagnetic nature of both compounds with some antiferromagnetic interactions at low-temperatures T < 20 K in 2 between the Co(II) cations separated by short pz linkers. Similar conclusions were also derived from the field-depending magnetization data of 1 and 2.

Reversible photo/thermal solid-state transformation of a coordination polymer

A 2D coordination polymer, 1, was synthesized, characterized, and investigated with single-crystal-to-single-crystal photoreaction and thermal pyrolysis.

Crystal structure of a two-dimensional coordination polymer of formula [Zn(NDC)(DEF)] (H2NDC is naphthalene-2,6-di-carb-oxy-lic acid and DEF is N,N-di-ethyl-formamide)

A zinc metal-organic framework, namely poly[bis-(N,N-di-ethyl-formamide)(μ4-naphthalene-2,6-di-carboxyl-ato)(μ2-naphthalene-2,6-di-carboxyl-ato)dizinc(II)], [Zn(C12H6O4)(C15H11NO)] n , built from windmill-type secondary building units and forming zigzag shaped two-dimensional stacked layers, has been solvothermally synthesized from naphthalene-2,6-di-carb-oxy-lic acid and zinc(II) acetate as the metal source in N,N-di-ethyl-formamide containing small amounts of formic acid.

Unsaturated Mn(II)-Centered [Mn(BDC)] n Metal-Organic Framework with Strong Water Binding Ability and Its Potential for Dehydration of an Ethanol/Water Mixture

An unsaturated Mn(II)-centered metal-organic framework was synthesized. The presence of an unsaturated Mn(II) center, together with a guest-responsive structural changing feature, plays a crucial role for strong binding with water, leading to its potential application for water/ethanol separation. In addition, the present framework is thermally stable up to 400 °C, which is beneficial for the regeneration process after adsorption.

Coordination polymers of 5-substituted isophthalic acid

The synthesis and characterisation of five coordination polymers - Ni2(mip)2(H2O)8·2H2O (1), Zn6(mip)5(OH)2(H2O)4·7.4H2O (2), Zn6(mip)5(OH)2(H2O)2·4H2O (3), Mn(HMeOip)2 (4), and Mn3(tbip)2(Htbip)2(EtOH)2 (5) - are reported. Preliminary nitric oxide release data on compounds 2 and 3 are also given.

Green synthesis, optical and magnetic properties of a MnIImetal–organic framework (MOF) that exhibits high heat of H2adsorption

Green synthesis of a 3D, Mn(ii) MOF, [Mn₃(NDC)₃(DMA)₄]n(1) has been achieved by employing mechanochemical and sonochemical routes and1′exhibits an interesting gas uptake properties with a high value of isosteric heat of adsorption (Q_st) for H₂.

Exploring biphenyl-2,4,4′-tricarboxylic acid as a flexible building block for the hydrothermal self-assembly of diverse metal–organic and supramolecular networks

This contribution reports the hydrothermal self-assembly synthesis, characterization, thermal stability, structural and topological features, and luminescence or magnetic properties of a new series of nine coordination compounds.

Metal–organic frameworks based on tri- and penta-nuclear manganese(ii) secondary building units self-assembled by a V-shaped silicon-containing dicarboxylate

SBUs consisting in penta- or trinuclear manganese(ii) are held together by cpdps²- or cpdps²- and Hcpdps- species derived from bis(p-carboxyphenyl)diphenylsilane in 2D (4,4) coordination polymers. Magnetic, thermal and moisture behaviors are studied.

Crystal structure of poly[(N,N-di-methyl-acetamide-κO)(μ4-5-methyl-isophthalato-κ(5) O:O,O':O'':O''')manganese(II)]

The title compound, poly[(N,N-di-methyl-acetamide-κO)(μ4-5-methyl-isophthalato-κ(5) O,O':O',O'':O'')manganese(II)], [Mn(C9H6O4)(C3H7NO)] n , was obtained from a mixture containing MnCl2·4H2O and 5-methyl-isophthalic acid in N,N-di-methyl-acetamide solution. The Mn(2+) ion is coordinated by five O atoms from four bridging 5-methyl-isophthalate ligands and one O atom from one N,N-di-methyl-acetamide ligand, defining a considerably distorted coordination polyhedron with one very long Mn-O bond of 2.623 (2) Å. The Mn(2+) ions are joined by carboxyl-ate groups, forming rod-shaped secondary building units along the a axis. The rods are further connected by 5-methyl-isophthalate ligands to form the pcu (primitive cubic net) structure.

Coordination polymers of ZnIIand 5-methoxy isophthalate

Four different coordination polymers were prepared by reaction of Zn(OAc)₂and 5-methoxy isophthalic acid using various aqueous/aqueous alcohol solvent systems.