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

No abstract

Progressive nitro functionalization of 4,4′-bipyrazole yields insensitive and stable high explosives with excellent densities and detonation properties.

A new strategy for supramolecular synthesis of energetic salts is reported. It is still a challenge to address packing patterns and crystal morphologies of such materials due to the lack of reliable supramolecular synthons, which are applicable to polynitro substituted species. 3,5-Dinitro-4,4′-bipyrazole (1), 3,3′,5-trinitro-4,4′-bipyrazole (2), and 3,3′,5,5′-tetranitro-4,4′-bipyrazole (3) are excellent functional models that provide a higher degree of control over the structure by manipulating robust self-assembly molecular building blocks of lower dimensionality. A variety of K+, Cs+, and nitrogen-rich salts (e.g., ammonium, aminoguanidinium, hydrazinium, and hydroxylammonium) 4–17, prepared by single deprotonation of NH-acidic 1–3, are based upon polar anionic chains sustained with strong NH···N bonding of conjugate acidic and basic pyrazole/pyrazolate sites. A gradual increase of NH-acidity (dinitropyrazolyl > nitropyrazolyl ≫ pyrazolyl) productively contributes to the strength of NH···N bonds and reliability of such supramolecular synthon. New synthesized energetic materials were fully characterized by NMR (1H, 13C, and 14N) spectroscopy, infrared spectroscopy, differential thermal analysis (DTA), and elemental analysis, and the heats of formation were calculated using the atomization method based on CBS-4 M enthalpies. Several detonation parameters, such as detonation pressure, velocity, and energy, were calculated by using the X-ray densities and the calculated standard molar enthalpies of formation. The sensitivities toward external stimuli were tested according to the BAM standards. In addition, the toxicity toward Vibrio fischeri bacteria of the monopotassium salt 9·H 2 O is reported.

Three metal−organic frameworks with the general formula Co(BPZX) (BPZX 2− = 3-X-4,4′-bipyrazolate, X = H, NH 2 , NO 2 ) constructed with ligands having different functional groups on the same skeleton have been employed as heterogeneous catalysts for aerobic liquid-phase oxidation of cumene with O 2 as oxidant. O 2 adsorption isotherms collected at p O2 = 1 atm and T = 195 and 273 K have cast light on the relative affinity of these catalysts for dioxygen. The highest gas uptake at 195 K is found for Co(BPZ) (3.2 mmol/g (10.1 wt % O 2 )), in line with its highest BET specific surface area (926 m 2 /g) in comparison with those of Co(BPZNH 2 ) (317 m 2 /g) and Co(BPZNO 2 ) (645 m 2 /g). The O 2 isosteric heat of adsorption (Q st ) trend follows the order Co(BPZ) > Co(BPZNH 2 ) > Co(BPZNO 2 ). Interestingly, the selectivity in the cumene oxidation products was found to be dependent on the tag present in the catalyst linker: while cumene hydroperoxide (CHP) is the main product obtained with Co(BPZ) (84% selectivity to CHP after 7 h, p O2 = 4 bar, and T = 363 K), further oxidation to 2-phenyl-2-propanol (PP) is observed in the presence of Co(BPZNH 2 ) as the catalyst (69% selectivity to PP under the same experimental conditions).