Ru-Xin Yao

A Luminescent Zinc(II) Metal–Organic Framework (MOF) with Conjugated π-Electron Ligand for High Iodine Capture and Nitro-Explosive Detection

A porous luminescent zinc(II) metal-organic framework (MOF) with a NbO net [Zn2(tptc)(apy)2-x(H2O)x]·H2O (1) (where x ≈ 1, apy = aminopyridine, H4tptc = terphenyl-3,3″,5,5″-tetracarboxylic acid), constructed using paddlewheel [Zn2(COO)4] clusters and π-electron-rich terphenyl-tetracarboxylic acid, has been solvothermally synthesized and characterized. Interestingly, the material displays efficient, reversible adsorption of radioactive I2 in vapor and in solution (up to 216 wt %). The strong affinity for I2 is mainly due to it having large porosity, a conjugated π-electron aromatic system, halogen bonds, and electron-donating aminos. Furthermore, luminescent study indicated that 1 exhibits high sensitivity to electron-deficient nitrobenzene explosives via fluorescence quenching.

Planar Mn4O Cluster Homochiral Metal−Organic Framework for HPLC Separation of Pharmaceutically Important (±)-Ibuprofen Racemate

A planar tetracoordinated oxygen containing a homochiral metal-organic framework (MOF) has been synthesized and characterized that can be used as a new chiral stationary phase in high-performance liquid chromatography to efficiently separate racemates such as pharmaceutically important (±)-ibuprofen and (±)-1-phenyl-1,2-ethanediol.

Heterometallic Mixed‐Valence Copper(I,II) Cyanides that were Tuned by Using the Chelate Effect: Discovery of Famous Cairo Pentagonal Tiling and Unprecedented (3,4)‐Connected {83}2{86} Topological 3D Net

By using environmentally friendly [Ni(CN)4](2-) as a cyanide source, three new heterometallic cyano-bridged mixed-valence Cu(I)/Cu(II) coordination polymers with three different electronic configurations (d(8)-d(10)), that is, [Cu2Ni(CN)5(H2O)3] (1), [Cu2Ni(CN)5(pn)H2O] (2), and [Cu3Ni(CN)6(pn)2] (3, pn = 1,2-propane diamine) have been synthesized by gradually increasing the amount of pn. Compound 1, which was hydrothermally synthesized in the absence of pn ligand, exhibits the famous 2D Cairo pentagonal tiling, in which the Cu(I), Cu(II), and Ni(II) atoms act as trigonal, T-shaped, and square-planar nodes, respectively. Notably, there are three water molecules located at the meridianal positions of the octahedrally coordinated Cu(II) atom in compound 1. A similar reaction, except for the addition of a small amount of pn, generated a similar Cairo pentagonal tiling layer in which two of the water molecules that were located at the meridianal positions of the octahedrally coordinated Cu(II) atom were replaced by a chelating pn group. Another similar hydrothermal reaction, with the addition of a larger amount of pn, yielded compound 3, which showed a related two-fold-interpenetrated (3,4)-connected 3D framework with an unprecedented {8(3)}2{8(6)} topology in which the Cu(II) atom was chelated by two pn groups. These structural changes between compounds 1-3 can be explained by the chelating effect of the pn group. The replacement of two meridianally coordinated water molecules on the octahedral Cu(II) atom in compound 1 by a pn group gives compound 2, which shows similar Cairo tiling, and a further increase in the amount of pn results in the formation of the [Cu(NC)2(pn)2] unit and the two-fold-interpenetrated 3D framework of compound 3. The mixed-valence properties of compounds 1, 2, and 3 were confirmed by variable-temperature magnetic-susceptibility measurements.

Fourfold-Interpenetrated MOF [Ni(pybz)2] as Coating Material in Gas Chromatographic Capillary Column for Separation

A fourfold interpenetrated diamond-like topological metal-organic framework (MOF), Ni(pybz)2 [pybz = 4-(4-pyridyl)benzoate] was successfully synthesized and fully characterized. This MOF can serve as coating material in gas chromatographic capillary column for the separation of some low boiling point essential oils. The prepared columns have good recognition ability and excellent selectivity toward a series of organic compounds, including alcohols, aldehydes, ketones, carboxylic acid, ethers, ester, and amines. It is found that the strained metal sites, van der Waals interactions, C-H···π attraction, and weak nonclassical hydrogen bond contribute to the recognition and selectivity of prepared columns. The grand canonical Monte Carlo technique is used to simulate the interactions of the adsorbates with MOF. The calculated van der Waals energies agree with the results of gas chromatographic separation.

Hexagonal Co6 and zigzag Co4 cluster based magnetic MOFs with a pcu net for selective catalysis

Two hydrophobic 3D cobalt-cluster based magnetic MOFs, [Co3(pimdc)2(H2O)6]·5H2O (1) and Co2(Hpimdc)2 (2) (H3pimdc = 2-propyl-imidazole-4,5-dicarboxylic acid), have been hydrothermally synthesized and magnetically characterized. Both of them exhibit a regular pcu net with hexagonal Co6 and zigzag Co4 clusters as 6-connected nodes, respectively. The magnetic studies indicate that 1 displays predominant antiferromagnetic interactions within the Co3(pimdc) triangle, while 2 shows spin-canting antiferromagnetic behaviour with larger canting angles. Furthermore, after heating under vacuum conditions, activated 1 exhibits an excellent catalytic selectivity in the allylic oxidation reaction of cyclohexene to form an α,β-unsaturated ketone, which indicates that the opened Co(II) sites play a significant role in the heterogeneous catalytic process.

Chiral metal–organic frameworks constructed from four-fold helical chain SBUs for enantioselective recognition of α-hydroxy/amino acids

The chiral recognition of racemic α-hydroxy/amino acids is an essential and challenging mission because enantiomers may profoundly differ in biological function, pharmacology and toxicity. Three stable, chiral 3D metal–carboxylate frameworks, namely [M2(bptc)(H2O)(MeOH)]·3H2O (bptc4− = 3,3′,5,5′-biphenyltetracarboxylate, M = Co, CoNi for 1–2, and [Ni2(bptc)(MeOH)2]·3H2O for 3) have been successfully obtained by spontaneous resolution with an achiral ligand H4bptc, and they crystallize in the chiral tetragonal space group I4122, and feature chiral four-fold helical metal chains as SBUs. In particular, the Co-MOF material could be used to rapidly and sensitively recognize racemic α-hydroxy/amino acids by the intensity change of circular dichroism signals. A large relative difference of 38.59% in circular dichroism signals for D/L-mandelic acid is achieved, which may be ascribed to the specific recognition sites (i.e., groove of helical chains) and different bonding energies of D/L-isomers in the chiral microenvironment of the crystal structure.