The amino-tagged bis(pyrazolate) MOF Zn(BPZNH2) is an excellent CO2 adsorbent and CO2 epoxidation catalyst under green conditions.

The metal-organic frameworks (MOFs) M(BPZNO ) (M=Co, Cu, Zn; H BPZNO =3-nitro-4,4'-bipyrazole) were prepared through solvothermal routes and were fully investigated in the solid state. They showed good thermal stability both under a N atmosphere and in air, with decomposition temperatures peaking up to 663 K for Zn(BPZNO ). Their crystal structure is characterized by 3D networks with square (M=Co, Zn) or rhombic (M=Cu) channels decorated by polar NO groups. As revealed by N adsorption at 77 K, they are micro-mesoporous materials with BET specific surface areas ranging from 400 to 900 m g . Remarkably, under the mild conditions of 298 K and 1.2 bar, Zn(BPZNO ) adsorbs 21.8 wt % CO (4.95 mmol g ). It shows a Henry CO /N selectivity of 15 and an ideal adsorbed solution theory (IAST) selectivity of 12 at p=1 bar. As a CO adsorbent, this compound is the best-performing MOF to date among those bearing a nitro group as a unique chemical tag. High-resolution powder X-ray diffraction at 298 K and different CO loadings revealed, for the first time in a NO -functionalized MOF, the insurgence of primary host-guest interactions involving the C(3)-NO moiety of the framework and the oxygen atoms of carbon dioxide, as confirmed by Grand Canonical Monte Carlo simulations. This interaction mode is markedly different from that observed in NH -functionalized MOFs, for which the carbon atom of CO is involved.

The four zinc(II) mixed-ligand MOFs (MIXMOFs) Zn(BPZ)x(BPZNO2)1-x, Zn(BPZ)x(BPZNH2)1-x, Zn(BPZNO2)x(BPZNH2)1-x and Zn(BPZ)x(BPZNO2)y(BPZNH2)1-x-y (H2BPZ = 4,4'-bipyrazole; H2BPZNO2 = 3-nitro-4,4'-bipyrazole; H2BPZNH2 = 3-amino-4,4'-bipyrazole) were prepared through solvothermal routes and fully investigated in the solid state. Isoreticular to the endmembers Zn(BPZ) and Zn(BPZX) (X = NO2, NH2), they are the first examples ever reported of (pyr)azolate MIXMOFs. Their crystal structure is characterized by a 3-D open framework with 1-D square or rhombic channels decorated by the functional groups. Accurate information about ligand stoichiometric ratio was determined (for the first time on MIXMOFs) through integration of selected ligands skeleton resonances from 13 C CPMAS solid-state NMR spectra collected on the as-synthesized materials. Like other poly(pyrazolate) MOFs, the four MIXMOFs are thermally stable, with decomposition temperatures between 708 and 726 K. As disclosed by N2 adsorption at 77 K, they are micro-mesoporous materials with BET specific surface areas in the range 400-600 m 2 /g. A comparative study (involving also the single-ligand analogues) of CO2 adsorption capacity, CO2 isosteric heat of adsorption (Qst) and CO2/N2 selectivity in equimolar mixtures at p = 1 bar and T = 298 K casted light on interesting trends, depending on ligand tag nature or ligand stoichiometric ratio. In particular, the amino-decorated compounds show higher Qst values and CO2/N2 selectivity vs. the nitro functionalized analogues; in addition, tag "dilution"[upon passing from Zn(BPZX) to Zn(BPZ)x(BPZX)1-x] increases CO2 adsorption selectivity over N2. The simultaneous presence of amino and nitro groups is not beneficial for CO2 uptake. Among the compounds studied, the best compromise among uptake capacity, Qst and CO2/N2 selectivity is represented by Zn(BPZ)x(BPZNH2)1-x. KeywordsMixed-ligand Metal-Organic Frameworks (MIXMOFs)zinccarbon dioxideporous materialsnitrogen ligandscarbon capture and sequestration (CCS) -13 C CPMAS NMR spectroscopy -15 N CPMAS NMR spectroscopy

A fluorous metal-organic framework [Cu(FBTB)(DMF)] (FMOF-3) [H 2 FBTB = 1,4-bis(1-H-tetrazol-5-yl)tetrafluorobenzene] and fluorous nonporous coordination polymer [Ag 2 (FBTB)] (FN-PCP-1) are synthesized and characterized as for their structural, thermal, and textural properties. Together with the corresponding nonfluorinated analogues lc-[Cu(BTB) (DMF)] and [Ag 2 (BTB)], and two known (super)hydrophobic MOFs, FMOF-1 and ZIF-8, they have been investigated as low-dielectric constant (low-κ) materials under dry and humid conditions. The results show that substitution of hydrogen with fluorine or fluoroalkyl groups on the organic linker imparts higher hydrophobicity and lower polarizability to the overall material. Pellets of FMOF-1, FMOF-3, and FN-PCP-1 exhibit κ values of 1.63(1), 2.44(3), and 2.57(3) at 2 × 10 6 Hz, respectively, under ambient conditions, versus 2.94(8) and 3.79(1) for lc-[Cu(BTB)(DMF)] and [Ag 2 (BTB)], respectively. Such low-κ values persist even upon exposure to almost saturated humidity levels. Correcting for the experimental pellet density, the intrinsic κ for FMOF-1 reaches the remarkably low value of 1.28, the lowest value known to date for a hydrophobic material.

Organophosphate nerve agents and pesticides are extremely toxic compounds because they result in acetylcholinesterase (AChE) inhibition and concomitant nerve system damage. Herein, we report the synthesis, structural characterization, and proof-of-concept utility of zirconium metal−organic polyhedra (Zr-MOPs) for organophosphate poisoning treatment. The results show the formation of robust tetrahedral cages [((n-butylCpZr) 3 (OH) 3 O) 4 L 6 ]Cl 6 (Zr-MOP-1; L = benzene-1,4dicarboxylate, n-butylCp = n-butylcyclopentadienyl, Zr-MOP-10, and L = 4,4′-biphenyldicarboxylate) decorated with lipophilic alkyl residues and possessing accessible cavities of ∼9.8 and ∼10.7 Å inner diameters, respectively. These systems are able to both capture the organophosphate model compound diisopropylfluorophosphate (DIFP) and host and release the AChE reactivator drug pralidoxime (2-PAM). The resulting 2-PAM@ Zr-MOP-1(0) host−guest assemblies feature a sustained delivery of 2-PAM under simulated biological conditions, with a concomitant reactivation of DIFP-inhibited AChE. Finally,