Temperature-induced structural diversity of metal–organic frameworks and their applications in selective sensing of nitrobenzene and electrocatalyzing the oxygen evolution reaction

Structural diversities are presented in four new Co-MOFs containing 1,5-bi(imidazolyl)anthracene and different dibenzobarrelene skeletons based on dicarboxylic acid, in which MOFs 1–3 exhibit 2D networks in a 4-connected node sql topology with the point symbol of {4⁴·6²}, while MOF 4 forms a 1D chain structure. It is clearly observed that the 2D-1D structural transformation of 2–4 has been realized by temperature modulated hydrothermal synthesis procedures from 120–160 °C, suggesting the key role of temperature for constructing MOFs. In addition, obvious π–π interactions between anthracene rings can be observed in the architectures of 1–3, which may favorably stabilize their 2D supramolecular networks. More importantly, fluorescence behaviors of 1–4 have been investigated in water among various nitro-aromatic compounds (NACs) and the results show that all samples exhibit high selectivity and fine sensitivity to nitrobenzene (NB) with fluorescence quenching, which is confirmed to be the result of electron transfer from the excited state of ligands to that of NB by density functional theory. Furthermore, MOFs 1–4 have been directly employed as electrocatalysts for the oxygen evolution reaction (OER), in which MOF 4 gives the best activity towards the OER among all as-synthesized samples with an overpotential of 398 mV at a current density of 10 mA cm⁻² and a low Tafel slope of 59 mV dec⁻¹.

Structure diversities can be observed in four new Co-MOFs by temperature modulated hydrothermal synthesis, which show high selectivity to nitrobenzene (NB) as well as promising oxygen evolution reaction (OER) activities.

Synthesis, structures and photoluminescence properties of mixed ligand divalent metal–organic frameworks

Crystal engineering is an effective route for synthesis of mixed ligand metal–organic frameworks with attractive topologies and versatile potential applications.

Hydrothermal synthesis and structural characterization of metal-organic frameworks based on new tetradentate ligands

The hydrothermal reaction of two new tetradentate ligands with different metal salts of cadmium nitrate, zinc chloride, cobalt nitrate and deprotonated terephthalic acid (H2tp), isophthalic acid (H2ip), 4,4'-oxybisbenzoic acid (H2obba) in H2O/DMF or H2O/methanol gave three metal-organic frameworks (MOFs): {[Zn2(L1)(tp)(formate)2]·H2O}n (), {[Cd2(L2)(ip)2]·2H2O}n (), {[Co2(L2)(obba)2]}n () (L1 = 1,2-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} ethane, L2 = 1,3-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} propane). The structures of the frameworks are established by single-crystal X-ray diffraction. Compound is a three-dimensional (3D) framework with a 2-fold interpenetrated form, which exhibits a 2-nodal (3,4)-connected fsh-3,4-P21/c net with a {8(3)}2{8(5)·10} topology. Compound has a 2-nodal (4,8)-connected 3D framework where the dinuclear cadmium cluster secondary building units (SBUs) assemble with isophthalate and ligand L2 to construct a rare topological type sqc22 net with a {3(2)·5(4)}{3(4)·4(4)·5(10)·6(10)} topology. Whereas, Compound can be extended to a 2D interlocked (4,4)-connected 4,4 L28 net with the point symbol {4·6(4)·8}2{4(2)·6(4)}. L1 and L2 are tetradentate ligands with diverse linkers and display different coordination modes. In addition, the thermal stability and photochemical properties of the frameworks are also investigated.

Self-triggered conformations of disulfide ensembles in coordination polymers with multiple metal clusters

Five coordination polymers containing manganese(ii) ions, 6,6′-dithiodinicotinate, and/or N-donor coligands display mononuclear, trinuclear cluster and polymeric metal oxide wire and exhibit intrinsic biomimetic characteristics.

Aminopyridine derivatives controlled the assembly and various properties of Cu–BTC metal–organic frameworks

Three Cu(ii) MOFs based on three aminopyridine derivatives and 1,3,5-benzenetricarboxylic acid have been synthesized and characterized. The electrocatalytic and photocatalytic properties of complexes 1–3 have been investigated in detail.