Reactions between the tritopic pyrazole-based ligand 1,3,5-tris(1H-pyrazol-4-yl)benzene (H3BTP) and transition metal acetate salts in DMF afford microporous pyrazolate-bridged metal–organic frameworks of the type M3(BTP)2*xsolvent (M = Ni (1), Cu, (2), Zn (3), Co (4)). Ab-initio X-ray powder diffraction methods were employed in determining the crystal structures of these compounds, revealing 1 and 2 to exhibit an expanded sodalite-like framework with accessible metal cation sites, while 3 and 4 possess tetragonal frameworks with hydrophobic surfaces and narrower channel diameters. Compounds 1–4 can be Desolvated without loss of crystallinity by heating under dynamic vacuum, giving rise to microporous solids with BET surface areas of 1650, 1860, 930 and 1027 m2/g, respectively. Thermogravimetric analyses and powder X-ray diffraction measurements demonstrate the exceptional thermal and chemical stability of these frameworks. In particular, 3 is stable to Heating in air up to at least 510 °C, while 1 is stable to heating in air to 430 °C, as well as to treatment with boiling aqueous solutions of pH 2 to 14 for two weeks. Unexpectedly, 2 and 3 are converted into new crystalline metal–organic frameworks upon heating in boiling water. With the combination of stability under extreme conditions, high surface area, and exposed metal sites, it is anticipated that 1 may open the way to testing metal–organic frameworks for catalytic processes that currently employ zeolites

Tunable hydrophobicity: Efficient air filters for the protection against chemical warfare agents might be achieved by surface functionalization of the pores in robust metal–organic frameworks (MOFs) with fluoroalkyl residues and the precise control of their pore size (see picture). These MOFs capture harmful volatile organic compounds even under extremely moist conditions (80 % relative humidity).

Highly porous homoleptic Ni(bpb) and Zn(bpb) materials have been obtained by reaction of nickel(II) and zinc(II) salts with the deprotonated form of the 1,4-(4-bispyrazolyl)benzene ligand (H 2 bpb). Ab-initio structure solution methods and thermodiffractometry have allowed the determination of their crystal structures, framework flexibility, and thermal stability. The different stereochemical requirements of the Ni(II) and Zn(II) ions induce, in Ni(bpb) and Zn(bpb), rhombic and square channels, respectively, accounting for 57 and 65% of the total cell volume. The two materials feature high adsorption capacities toward small gaseous molecules (N 2 and Ar at 77 K, CO 2 and CH 4 at 273 K), peaking at 22 mmol g -1 of N 2 in the case of the zinc(II) derivative, which is reflected by a very large surface area (above 2000 m 2 g -1 ). The flexibility, size, and hydrophobic nature of their channels are adequate also for the incorporation of organic vapors. In this regard, the adsorption of benzene and cyclohexane has been studied under static conditions at 303 K, while that of thiophene has been investigated in dynamic conditions, by measurement, at 298 K, of the breakthrough curves of a flow of CH 4 /CO 2 containing 30 ppm of thiophene. Ni(bpb) and Zn(bpb) are outperforming adsorbents, uptaking up to 0.34 g of thiophene per gram of material. The presence of humidity (60%), which is a major drawback for practical applications of MOFs, does not significantly affect the performance of Ni(bpb) in the removal of thiophene, at variance with Zn(bpb) and HKUST-1, Cu 3 (btc) 2 (btc = benzene-1,3,5-tricarboxylate), which become ineffective in the presence of moisture. Additional XRPD studies have been performed on benzene-loaded Ni(bpb) samples in order to shed some light on the affinity of this material for aromatic guests.

Two isoreticular series of pyrazolate-based 3D open metal-organic frameworks, MBDP_X, adopting the NiBDP and ZnBDP structure types [H(2)BDP = 1,4-bis(1H-pyrazol-4-yl)benzene], were synthesized with the new tagged organic linkers H(2)BDP_X (X = -NO(2), -NH(2), -OH). All of the MBDP_X materials have been characterized through a combination of techniques. IR spectroscopy proved the effective presence of tags, while X-ray powder diffraction (XRPD) witnessed their isoreticular nature. Simultaneous TG/DSC analyses (STA) demonstrated their remarkable thermal stability, while variable-temperature XRPD experiments highlighted their high degree of flexibility related to guest-induced fit processes of the solvent molecules included in the channels. A structural isomer of the parent NiBDP was obtained with a sulfonate tagged ligand, H(2)BDP_SO(3)H. Structure solution from powder diffraction data collected at three different temperatures (room temperature, 90, and 250 °C) allowed the determination of its structure and the comprehension of its solvent-related flexible behavior. Finally, the potential application of the tagged MOFs in selective adsorption processes for gas separation and purification purposes was investigated by conventional single component adsorption isotherms, as well as by advanced experiments of pulse gas chromatography and breakthrough curve measurements. Noteworthy, the results show that functionalization does not improve the adsorption selectivity (partition coefficients) for the resolution of gas mixtures characterized by similar high quadrupole moments (e.g., CO(2)/C(2)H(2)); however, the resolution of gas mixtures containing molecules with highly differentiated polarities (i.e., N(2)/CO(2) or CH(4)/CO(2)) is highly improved.

Two highly porous coordination polymers, containing rare octanuclear hydroxo-nickel clusters and long bis-pyrazolyl spacers, are shown to possess, after mild thermal treatment, lattice cavities up to 72% of the total crystal volume.

Einstellbare Hydrophobie: Effiziente Luftfilter zum Schutz gegen chemische Kampfmittel können durch Oberflächenfunktionalisierung der Poren stabiler Metall‐organischer Gerüste (MOFs) mit Fluoralkylresten und präzise Kontrolle der Porengröße erhalten werden (siehe Bild). Diese MOFs können schädliche flüchtige organische Verbindungen unter extrem feuchten Bedingungen (80 % relative Feuchtigkeit) einfangen.

The reaction of [Cu(CH(3)CN)(4)](BF(4)) with 3,5-dimethyl-4-nitropyrazole (Hdmnpz) in the presence of triethylamine yields the new copper(I) complexes [Cu(dmnpz)](3) (1) and (Et(3)NH)(2)[Cu(4)(dmnpz)(6)] (2), depending on the experimental conditions. The reactivity of 1 and 2 toward neutral ligands such as triphenylphosphine, cyclohexyl isocyanide (RNC), and carbon monoxide has been investigated. In particular, both complexes readily react with RNC, giving the dinuclear complexes [Cu(dmnpz)(RNC)](2) (4) and [Cu(dmnpz)(RNC)(2)](2) (5), depending on the copper/RNC ratio, and with PPh(3), affording the dimeric derivative [Cu(dmnpz)(PPh(3))](2) (6). The crystal and molecular structure of 1 has been determined ab initio using X-ray powder diffraction data from conventional laboratory equipment. Crystals of 1 are monoclinic, C2/c, a = 20.057(2) Å, b = 13.816(2) Å, c = 7.883(1) Å, beta = 95.912(4) degrees; R(F) and R(wp) 0.067 and 0.039, respectively, for Rietveld refinement on 3900 data points collected in the range 17 < 2theta < 95 degrees (Cu Kalpha radiation). Crystals of 1 contain planar trimers, with the copper atoms bridged by exo-bidentate ligands and short intermolecular Cu.Cu contacts (3.329(7) Å). For complexes 2 and 4-6, single-crystal X-ray diffraction studies have been performed. Crystals of 2 are monoclinic, P2(1)/c, a = 11.026(1) Å, b = 13.456(2) Å, c = 18.668(5) Å, beta = 92.91(2) degrees, Z = 2. The ionic packing of 2 contains tetranuclear complexes, with the copper atoms connected by six dmnpz ligands. Crystals of 4 are triclinic, P&onemacr;, a = 7.418(1) Å, b = 9.780(1) Å, c = 11.177(3) Å, alpha = 109.61(2); beta = 101.34(3) degrees, gamma = 105.82(1) degrees, Z = 2. Crystals of 5 are triclinic, P&onemacr;, a = 9.506(4) Å, b = 9.957(2) Å, c = 11.658(4) Å, alpha = 86.73(2) degrees, beta = 79.54(2) degrees, gamma = 82.47(4) degrees, Z = 1. Crystals of 6 are triclinic, P&onemacr;, a = 11.379(2) Å, b = 13.592(2) Å, c = 14.409(3) Å, alpha = 81.22(1) degrees, beta = 85.21(1) degrees, gamma = 87.55(1) degrees, Z = 2. 4, 5, and 6 are binuclear complexes bearing one RNC, two RNC, and one triphenylphosphine ligands on each copper atom, respectively. The steric requirement of the dmnpz ligands, in the presence of RNC or PPh(3), forces the inner [Cu(2)(dmnpz)(2)] core of the three complexes into markedly different conformations.

A number of coordination polymers of the pymo ligand (Hpymo = 2‐hydroxypyrimidine) have been prepared and fully characterized by chemical, spectroscopic, and thermal analyses. Their complete crystal structures have been solved ab initio from laboratory X‐ray powder diffraction data and ultimately refined by the Rietveld method. The M(pymo)2 species (M = Co, Ni, Zn) consist of structurally related three‐dimensional frameworks of very high thermal stability (decomposing under N2 only at T > 550 °C), with the metal atoms, linked by μ2‐η1‐η1 (N;N′) (Co, Zn) or μ2‐η2‐η1 (N,O;N′) bridges, about 5.4−5.7 Å apart. The hydrated species Ni(pymo)2(H2O)2.5 is based on a two‐dimensional array of Ni(pymo)2 stoichiometry, containing both coordinated and clathrated water molecules, and can be selectively transformed into Ni(pymo)2 by thermal treatment, through an amorphous intermediate, recrystallizing at T > 315 °C. In contrast, one dimensional chains are found in the three hydrazine adducts, M(pymo)2(N2H4)2, which show unique bis(μ2‐hydrazine) bridges (M···M ca. 4.0 Å) and terminally O‐bonded pymo ligands.