Straightforward Mechanosynthesis of a Phase-Pure Interpenetrated MOF‑5 Bearing a Size-Matching Tetrazine-Based Linker

The archetypal metal-organic framework-5 (MOF-5 or IRMOF-1) has been explored as a benchmark sorbent material with untapped potential to be studied in the capture and storage of gases and chemical confinement. Several derivatives of this framework have been prepared using the multivariate (MTV) strategy through mixing size-matching linkers to isolate, for example, MIXMOFs that outperform same-linker congeners when employed as gas reservoirs. Herein, we describe a straightforward protocol that uses mechanosynthesis (solvent-free grinding) followed by mild activation in dimethylformamide (DMF)/CHCl3 (40 °C and ambient pressure) to synthesize a functional phase-pure interpenetrated MOF-5 (int-MOF-5) bearing the size-matching 1,4-benzene dicarboxylate (BDC) and 1,2,4,5-tetrazine-3,6-dicarboxylate (TZDC) linkers in the backbone of the interpenetrated MIXMOF. We found that the grinding involving a mixture of H2TZDC and H2BDC in a 1:4 ratio (20% of H2TZDC) in the presence of zinc­(II) acetate yields a crystalline solid that upon activation forms a phase-pure int-MOF-5 herein referred to as 20%TZDC-MOF-5. The crystalline phase, thermal stability, and porous structure of 20%TZDC-MOF-5 were thoroughly characterized, and the gas adsorption performance of the MIXMOF was investigated through the isotherms of N2 and H2 at 77 K and CO2 at 273 and 296 K. The pore size distribution for 20%TZDC-MOF-5 was found to be very similar to that determined using single crystals of the same-linker int-MOF-5. The presence of TZDC in the MIXMOF led to a slight increase in the uptake values for both H2 and CO2, suggesting that beneficial interactions take place. To the best of our knowledge, this is the first report presenting a suitable protocol to yield a functionalized int-MOF-5 as a promising means of synergistically fine-tuning the confinement of small target molecules such as CO2 and H2

A Systematic Evaluation of the Interplay of Weak and Strong Supramolecular Interactions in a Series of Co(II) and Zn(II) Complexes Tuned by Ligand Modification

A systematic investigation on a designed series of 21 transition metal complexes has been carried out with the intention to explore and assess the relative strength and the way in which intermolecular interactions, namely, weak and strong hydrogen-bonding and π–π interactions, cooperate and direct molecular association during crystallization. The complexes were prepared using the general MII/X–/L or HL′ (MII = CoII, ZnII; X– = Cl–, Br–, I–, NO3–, NO2–, ClO4–; L = 1-methyl-4,5-diphenylimidazole; and HL′ = 4,5-diphenylimidazole) reaction system and were characterized by single-crystal X-ray crystallography. Although the two ligands are structurally similar, the crystal packing organization of their complexes is markedly different. In structures with L, the 3D assembly is based only on weak C–H···X, C–H···π, and intramolecular π···π stacking interactions, whereas in those with HL′, it is the recurring N–H···X motifs that clearly dominate and guide the molecular self-assembly. The formation of such synthons has been activated by choosing appropriate anions X, acting as terminal ligands or counterions. In parallel, the conformational flexibility of the two ligands serves a dual purpose: (i) L contributes to the stabilization of complexes via intramolecular π···π stacking interactions, and (ii) HL′ facilitates the synthon formation by adopting appropriate conformations, even at the expenses of the stabilizing intramolecular π···π stacking

A Systematic Evaluation of the Interplay of Weak and Strong Supramolecular Interactions in a Series of Co(II) and Zn(II) Complexes Tuned by Ligand Modification

A systematic investigation on a designed series of 21 transition metal complexes has been carried out with the intention to explore and assess the relative strength and the way in which intermolecular interactions, namely, weak and strong hydrogen-bonding and π–π interactions, cooperate and direct molecular association during crystallization. The complexes were prepared using the general M^II/X^–/L or HL′ (M^II = Co^II, Zn^II; X^– = Cl^–, Br^–, I^–, NO₃^–, NO₂^–, ClO₄^–; L = 1-methyl-4,5-diphenylimidazole; and HL′ = 4,5-diphenylimidazole) reaction system and were characterized by single-crystal X-ray crystallography. Although the two ligands are structurally similar, the crystal packing organization of their complexes is markedly different. In structures with L, the 3D assembly is based only on weak C–H···X, C–H···π, and intramolecular π···π stacking interactions, whereas in those with HL′, it is the recurring N–H···X motifs that clearly dominate and guide the molecular self-assembly. The formation of such synthons has been activated by choosing appropriate anions X, acting as terminal ligands or counterions. In parallel, the conformational flexibility of the two ligands serves a dual purpose: (i) L contributes to the stabilization of complexes via intramolecular π···π stacking interactions, and (ii) HL′ facilitates the synthon formation by adopting appropriate conformations, even at the expenses of the stabilizing intramolecular π···π stacking

pH-Dependent Formation of Two Dihydrazinyltetrazine–Azobistetrazolate Salts with Different Thermal Stabilities and Energetic Performance

Two new energetic salts were prepared through the combination of 3,6-dihydrazinyl-1,2,4,5-tetrazine dichloride ([H2DHT]Cl2) and disodium 5,5′-azobis(tetrazolate) pentahydrate (Na2AZT·5H2O) in different pH conditions. Under acidic conditions, the 1:1 salt [H2DHT][AZT]·2H2O (2·2H2O) was isolated, while neutral pH gave access to the formation of the 2:1 salt ([HDHT]2[AZT]·4H2O; 3·4H2O). Both compounds were characterized by IR and NMR spectroscopy, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), as well as single crystal and powder X-ray diffraction. Based on experimental data, compound 2·2H2O was found to be more thermally stable, with a decomposition temperature of Tdec = 107 °C, compared to compound 3·4H2O (Tdec = 99 °C). Non-covalent interactions (hydrogen bonds and π–π interactions) were evaluated to better understand the structure–property relationships, revealing the effect of crystal packing on the overall energetic properties

Rare Oxidation-State Combinations and Unusual Structural Motifs in Hexanuclear Mn Complexes Using 2-Pyridyloximate Ligands

The use of phenyl-2-pyridyl ketone oxime and di-2-pyridyl ketone oxime in Mn chemistry has led to hexanuclear clusters with unprecedented (MnII4MnIIIMnIV) or extremely rare (MnIIMnIII5 and MnII3MnIII3) metal oxidation-state combinations and uncommon structural motifs

Rare Oxidation-State Combinations and Unusual Structural Motifs in Hexanuclear Mn Complexes Using 2-Pyridyloximate Ligands

The use of phenyl-2-pyridyl ketone oxime and di-2-pyridyl ketone oxime in Mn chemistry has led to hexanuclear clusters with unprecedented (MnII4MnIIIMnIV) or extremely rare (MnIIMnIII5 and MnII3MnIII3) metal oxidation-state combinations and uncommon structural motifs

Rare Oxidation-State Combinations and Unusual Structural Motifs in Hexanuclear Mn Complexes Using 2-Pyridyloximate Ligands

The use of phenyl-2-pyridyl ketone oxime and di-2-pyridyl ketone oxime in Mn chemistry has led to hexanuclear clusters with unprecedented (MnII4MnIIIMnIV) or extremely rare (MnIIMnIII5 and MnII3MnIII3) metal oxidation-state combinations and uncommon structural motifs

Rare Oxidation-State Combinations and Unusual Structural Motifs in Hexanuclear Mn Complexes Using 2-Pyridyloximate Ligands

The use of phenyl-2-pyridyl ketone oxime and di-2-pyridyl ketone oxime in Mn chemistry has led to hexanuclear clusters with unprecedented (MnII4MnIIIMnIV) or extremely rare (MnIIMnIII5 and MnII3MnIII3) metal oxidation-state combinations and uncommon structural motifs