Xiao-Ning Cheng

The slow magnetic relaxation observed in a mixed carboxylate/hydroxide-bridged compound [Co2Na(4-cpa)2(μ3-OH)(H2O)]∞ featuring magnetic Δ-chains

Magnetic Δ-chains in a 3D coordination polymer [Co2Na(4-cpa)2(μ3-OH)(H2O)]∞ are well separated by Na+ ions and organic spacers, and exhibit not only magnetic behaviour of Δ-chain topology but also slow magnetic relaxation.

Two microporous metal–organic frameworks with different topologies constructed from linear trinuclear M3(COO)n secondary building units

Two new microporous metal–organic frameworks, [Zn3(NH2BDC)3(H2O)2]·5DMF (1) and (Me2NH2)2[Cd3(NH2BDC)4]·2DMF·2.5 H2O (2) (NH2BDC = 2-amino-1,4-benzenedicarboxylate), based on linear trinuclear secondary building units of Zn3(COO)6 or Cd3(COO)8 that have different connected numbers, have been synthesized and characterized, which exhibit usual pcu and rare hex-like topologies, respectively. Both 1 and 2 are three-dimensional porous frameworks, having solvent accessible volumes of ca. 53 and 39%, respectively. There are unremovable guest Me2NH2+ cations clogged in the channels of 2. In contrast, being of good thermo-stability, 1 has a Langmuir surface area about 570 m2 g−1 and type I isotherm behaviour for nitrogen gas sorption at 77 K, being typical of microporous material.

Magnetic variation induced by structural transformation from coordination chains to layers upon dehydration

The reaction of CoBr(2), 1,2-di(4H-1,2,4-triazol-4-yl)diazene (bta) and KSCN yielded a one-dimensional coordination polymer [Co(SCN)(2)(bta)(H(2)O)(2)] with water molecules coordinated to the metal ions. After dehydration at 100 °C, the compound transformed into a layered coordination polymer [Co(SCN)(2)(bta)], whose structure was determined by powder X-ray diffraction based on the single-crystal structure of another layered coordination polymer [Cd(SCN)(2)(bta)]. Interestingly, a magnetic variation from a simple paramagnet to an antiferromagnetic ordered phase of a single-chain-magnet that exhibits both metamagnetic behaviour and slow magnetic relaxation was observed upon the dehydration process.

Metal ion modulation of polycatenation networks constructed by mixed rigid and flexible bridging ligands

Self-assembly of Ni(II)/Co(II) with 4,4′-oxybis(benzoate) and 4,4′-bipyridyl under hydrothermal conditions yielded polyrotaxane ring-and-rod double chains and 6-fold interpenetrated (10,3)-a coordination networks.

Flexible, Luminescent Metal–Organic Frameworks Showing Synergistic Solid-Solution Effects on Porosity and Sensitivity

Mixing molecular building blocks in the solid solution manner is a valuable strategy to obtain structures and properties in between the isostructural parent metal-organic frameworks (MOFs). We report nonlinear/synergistic solid-solution effects using highly related yet non-isostructural, phosphorescent CuI triazolate frameworks as parent phases. Near the phase boundaries associated with conformational diversity and ligand heterogeneity, the porosity (+150 %) and optical O2 sensitivity (410 times, limit of detection 0.07 ppm) can be drastically improved from the best-performing parent MOFs and even exceeds the records hold by precious-metal complexes (3 ppm) and C70 (0.2 ppm).