Synthesis, Structures, And Magnetic Behavior of New Anionic Copper(II) Sulfate Aggregates and Chains

The reaction between CuSO₄·5H₂O and [NMe₂H₂]Cl in <i>N</i>,<i>N</i>′-dimethylformamide (DMF) at 95 °C yielded green crystals of (NMe₂H₂)₄[Cu₆O₂(SO₄)₆(DMF)₄] <b>1</b>. The discrete [Cu₆(μ₄-O)₂(μ₃-SO₄)₄(μ₂-SO₄)₂(DMF)₄]^4– anions present in <b>1</b> contain two edge-sharing Cu₄(μ₄-O) tetrahedra, with the copper­(II) centers bridged by sulfato ligands. These anions are linked into a two-dimensional network through hydrogen bonds involving the dimethylammonium cations. When the reaction was carried out in the absence of [NMe₂H₂]­Cl, yellow-green crystals of (NMe₂H₂)₄[Cu₆O₂(SO₄)₆(DMF)₂] <b>2</b> were obtained. The anions in <b>2</b> contain similar Cu₆O₂(SO₄)₆ aggregates to those in <b>1</b>, though these differ in terms of the copper­(II) coordination geometries. In addition, the anions in <b>2</b> are linked into chains through bridging sulfato ligands. The Cu₆O₂(SO₄)₆ aggregates observed in <b>1</b> and <b>2</b> are related to those present in the rare copper sulfate mineral fedotovite, K₂Cu₃O­(SO₄)₃, and in common with this mineral both <b>1</b> and <b>2</b> decompose in the presence of moisture. The reaction between CuSO₄·5H₂O and [NMe₂H₂]­Cl in DMF at room temperature gave (NMe₂H₂)­[Cu₂(OH)­(SO₄)₂(H₂O)₂] <b>3</b>, the structure of which contains triangular Cu₃(OH)­(SO₄) units that share vertices to form tapes. Magnetic measurements revealed that <b>1</b> and <b>3</b> are both spin-canting metamagnetic systems. Field-induced responses were observed below 5 K, with the critical field indicating metamagnetic behavior from antiferromagnetic to ferromagnetic equal to 110 Oe for both compounds

Mixed-Component Sulfone–Sulfoxide Tagged Zinc IRMOFs: <i>In Situ</i> Ligand Oxidation, Carbon Dioxide, and Water Sorption Studies

Reported here are the syntheses and adsorption properties of a series of single- and mixed-component zinc IRMOFs derived from controlled ratios of sulfide and sulfone functionalized linear biphenyldicarboxylate (bpdc) ligands. During MOF synthesis the sulfide moieties undergo <i>in situ</i> oxidation, giving rise to sulfoxide functionalized ligands, which are incorporated to give mixed-component sulfoxide–sulfone functionalized MOFs. The single- and mixed-component systems all share the IRMOF-9 structure type as determined by a combination of single crystal and powder X-ray diffraction analyses. The functionalized IRMOF-9 series was investigated by N₂, CO₂, and water adsorption measurements. MOFs containing higher proportions of sulfoxide have slightly larger accessible surface areas and pore volumes, whereas MOFs containing a greater proportion of the sulfone functionality demonstrated higher CO₂ adsorption capacities, enthalpies of CO₂ adsorption, and CO₂/N₂ selectivities. Water adsorption studies at 298 K showed the MOFs to have pore-filling steps starting around 0.4 <i>P/P</i>₀. In general, only small changes in water adsorption were observed with regards to ligand ratios in the mixed-component MOFs, suggesting that the location of the step is primarily determined by the pore size. A ligand-directed fine-tuning approach of changing alkyl chain length was demonstrated to give smaller more hydrophobic pores with better adsorption characteristics