Hong-Rui Tian

Photochromic Terbium Phosphonates with Photomodulated Luminescence and Metal Ion Sensitive Detection.

Rational selection and modification of rare earth metal centers and photoactive organic linkers enables designable multiphotofunctionality to come to fruition in new hybrid coordination polymer materials. By using a viologen-functionalized diphosphonate linker, two terbium phosphonate compounds (Tb-1 and Tb-2) have been constructed, which display reversible photochromic reactions in response to UV light and soft X-ray irradiation. In addition, the photo-induced electron-transfer reaction can modulate the luminescent emission to thus realize photoluminescence switching behavior. Furthermore, both terbium phosphonates can serve as highly sensitive sensors to probe Cu2+ in solution through their luminescence. Thus, they represent the first photochromic examples of lanthanide phosphonate-based materials with photomodulated luminescence and sensitive detection of metal ions.

Particular Handedness Excess through Symmetry-Breaking Crystallization of a 3D Cobalt Phosphonate.

A 3D chiral cobalt phosphonate has been obtained from achiral precursors in the absence of chiral inducers. Remarkably, the bulk sample is largely enantio-enriched with particular handedness through symmetry-breaking crystallization in spite of multiple repeated experiments. Moreover, protonation of this chiral material introduces Brønsted acid sites, the structure of which is unique to the heterogeneous phase for the ring opening of epoxies.

A microporous Cd-MOF based on a hexavalent silicon-centred connector and luminescence sensing of small molecules

Solvothermal reaction of Cd2+ cations with a silicon-centered carboxylic acid (H6L) afforded a novel metal–organic framework, namely, [Cd3L(H2O)5]·DMA·H2O (1). It is built from three {CdO6} clusters and organosilicone linkers to form a 3D porous framework. The steric organosilicone ligand is among the never documented examples. Interestingly, 1 exhibited spontaneous formations of microtubular crystals, the phenomenon of which is rarely reported among the metal–organic coordination assemblies. In addition, the luminescence properties of 1 dispersed in different organic solvents have been investigated, displaying turn-on and turn-off luminescence responses for n-butanol and acetone, respectively.

Metal–organic frameworks constructed from a tetrahedral silicon-based linker for selective adsorption of methylene blue

The solvothermal assemblies of Cd(II)/Co(II)/Zn(II) ions, a silicon-centered tetrahedral ligand as a principal building block, and a N-donor ancillary ligand yield three metal–organic frameworks, formulated as [Cd2(H2O)2L]·5H2O·0.5DMF (1), [Co3O(H2O)3L(ttb)]·3H2O (2), [Zn3O(H2O)2L(ttb)(DMF)2]·2H2O (3) [H4L = 4,4′,4′′,4′′′-silanetetrayltetrabenzoic acid, ttp = 1-(tetrazo-5-yl)-4-(triazo-1-yl)benzene, DMF = N,N-dimethylformamide], respectively. Single-crystal X-ray diffraction analysis demonstrated that all compounds feature three-dimensional structures with different secondary building units. Their permanent porosities were established by the N2 sorption isotherm at 77 K. The adsorption behavior of 1 towards organic dyes was investigated, revealing rapid and selective separation of methylene blue with a maximum uptake of 1008 mg g−1.

Designed Cluster Assembly of Multidimensional Titanium Coordination Polymers: Syntheses, Crystal Structure and Properties

The exploitation of new titanium-based coordination polymers (Ti CPs) with high crystallinity is difficult but highly desirable for their potential applications in photocatalysis. Herein, a cluster-cooperative assemble strategy is developed to synthesize Ti CPs. By utilizing various bifunctional ligands containing carboxylate acids and N-donor groups, we successfully assembled the zero-dimensional (0D) [(Ti3 O)(iPrO)8 ]2+ or [(Ti4 O2 )(iPrO)6 ]6+ clusters into one-dimensional (1D) tube-, ribbon-, or helical chain-shape architectures, two-dimensional (2D) layered structures, and a rare parallel 2D→three-dimensional (3D) polycatenation framework with various copper iodide dopants, including rhombus- or wing-shaped Cu2 I2 and tetrahedron- or ladder-shaped Cu4 I4 . The as-synthesized compounds display strong absorption in the visible region with narrow band gaps ranging from 1.70 to 2.72 eV and exhibit good photocatalytic activities in the degradation of organic pollutants.

Porous Anionic Uranyl–Organic Networks for Highly Efficient Cs+ Adsorption and Investigation of the Mechanism

Exploitation of new materials for the removal of long-lived and highly radioactive actinides and their fission products produced in the nuclear fuel cycle is crucial for radionuclide management. Here, two rare porous anionic uranyl-organic frameworks (UOFs) have been successfully synthesized by a judicious combination of the tetratopic carboxylate ligand 1,3,6,8-tetrakis( p-benzoic acid)pyrene (H4TBAPy) and D3 h-symmetrical triangular [UO2(COO)3]-. The resulting two compounds exhibit different architectures, albeit with similar coordination modes. Of interest is that they have excellent adsorption performance on Cs+ from aqueous solution. The high removal efficency would make them promising in applications of radioactive waste management. Notably, the framework of compound 2, [(CH3)2NH2]4[(UO2)4(TBAPy)3]·22DMF·37H2O is sufficiently robust to allow the accessibility of intriguing single crystals of a Cs+-adsorbed derivative, which helps to elucidate the adsorption mechanism. The structural, bonding, and spectroscopic properties of the above compounds are examined using relativistic density functional theory (DFT). It is found that the adsorption toward cesium on UOFs is energetically favored, which features largely ionic bonds and is dominated by electrostatic attraction.

Interpenetrated Uranyl–Organic Frameworks with bor and pts Topology: Structure, Spectroscopy, and Computation

Two novel three-dimensional interpenetrated uranyl-organic frameworks, (NH4)4[(UO2)4(L1)3]·6H2O (1) and [(UO2)2(H2O)2L2]·2H2O (2), where L1 = tetrakis(3-carboxyphenyl)silicon and L2 = tetrakis(4-carboxyphenyl)silicon, were synthesized by a combination of two isomeric tetrahedral silicon-centered ligands with 3-connected triangular [(UO2)(COO)3]- and 4-connected dinuclear [(UO2)2(COO)4] units, respectively. Structural analyses indicate that 1 possesses a 2-fold interpenetrating anion bor network, while 2 exhibits a 3-fold interpenetrated 4,4-connected neutral network with pts topology. Both compounds were characterized by thermogravimetric analysis and IR, UV-vis, and photoluminescence spectroscopy. A relativistic density functional theory (DFT) investigation on 10 model compounds of 1 and 2 shows good agreement of the structural parameters, stretching vibrational frequencies, and absorption with experimental results; the time-dependent DFT calculations unravel that low-energy absorption bands originate from ligand-to-uranium charge transfer.