Jia-Yue Tian

Ligand Symmetry Modulation for Designing a Mesoporous Metal–Organic Framework: Dual Reactivity to Transition and Lanthanide Metals for Enhanced Functionalization

A promising alternative strategy for designing mesoporous metal-organic frameworks (MOFs) has been proposed, by modifying the symmetry rather than expanding the length of organic linkers. By means of this approach, a unique MOF material based on the target [Zn8(ad)4] (ad = adeninate) clusters and C3-symmetric organic linkers can be obtained, with trigonal microporous (ca., 0.8 nm) and hexagonal mesoporous (ca., 3.0 nm) 1D channels. Moreover, the resulting 446-MOF shows distinct reactivity to transition and lanthanide metal ions. Significantly, the transmetalation of Co(II) or Ni(II) on the Zn(II) centers in 446-MOF can enhance the sorption capacities of CO2 and CH4 (16-21%), whereas the impregnation of Eu(III) and Tb(III) in the channels of 446-MOF will result in adjustable light-emitting behaviors.

A terbium(III) lanthanide–organic framework as a platform for a recyclable multi-responsive luminescent sensor

A terbium(III) lanthanide–organic framework (534-MOF-Tb) with a green-emission signal was successfully obtained by the solvothermal reaction of Tb3+ ions with the organic ligand H3TBOT (2,4,6-tris[1-(3-carboxylphenoxy)ylmethyl]mesitylene). 534-MOF-Tb contains microporous quadrangle channels with accessible Lewis-base sites and coordinated water molecules, which are feasible to anchor and recognise multifarious analytes. It can serve as a recyclable multi-responsive sensing material for detecting Fe3+, MnO4−, Cr2O72−, and p-nitrotoluene (4-NT). Significantly, this is the first reported MOF-based sensor for detecting explosive 4-NT. Moreover, the mechanism of the selective luminescence quenching response for Fe3+, MnO4−, Cr2O72− or 4-NT can be mainly explained in terms of the competition between the absorption of the light source energy and the electronic interaction between the analyte and the TBOT ligand.

Charge Control in Two Isostructural Anionic/Cationic CoII Coordination Frameworks for Enhanced Acetylene Capture

Two isostructural CoII -based metal-organic frameworks (MOFs) with the opposite framework charges have been constructed, which can be simply controlled by changing the tetrazolyl or triazolyl terminal in two bifunctional ligands. Notably, the cationic MOF 2 can adsorb much more C2 H2 than the anionic MOF 1 with an increase of 88 % for C2 H2 uptake at 298 K in spite of more active nitrogen sites in 1. Theoretical calculations indicate that both nitrate and triazolyl play vital roles in C2 H2 binding and the C2 H2 adsorption isotherm confirms that the enhanced C2 H2 uptake for 2 (225 and 163 cm3 g-1 at 273 and 298 K) is exceptionally high for MOF materials without open metal sites or uncoordinated polar atom groups on the frameworks.

Two isomeric Zn(II)-based metal–organic frameworks constructed from a bifunctional triazolate–carboxylate tecton exhibiting distinct gas sorption behaviors

Two isomeric Zn(II)-based metal–organic frameworks, {[Zn(CPT)2](NMF)3}n (1) and {[Zn(CPT)2](DMF)0.75}n (2) (HCPT = 4-(4-carboxyphenyl)-1,2,4-triazole, NMF = N-methylformamide, DMF = N,N-dimethylformamide), with the same 4-fold interpenetrated dia topological network have been prepared under solvothermal conditions by employing a bifunctional triazolate–carboxylate organic linker, which show very similar voids but different pore shapes. Thermogravimetry, powder X-ray diffraction, molecular mechanics calculation, and gas sorption studies revealed their different framework stabilities and flexibilities, in which desolvated 1 exhibits temperature-dependent stepwise and hysteretic selective sorption of CO2 over N2 at 195 K, whereas desolvated 2 could adsorb neither CO2 nor N2. Furthermore, the luminescence properties of 1 and 2 were investigated.

Tracking the Superefficient Anion Exchange of a Dynamic Porous Material Constructed by Ag(I) Nitrate and Tripyridyltriazole via Multistep Single-Crystal to Single-Crystal Transformations

To avoid the instability and inefficiency for anion-exchange resins and layered double-hydroxides materials, we present herein a flexible coordination network [Ag(L243)](NO3)(H2O)(CH3CN) (L243 = 3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole) with superefficient trapping capacity for permanganate, as a group-7 oxoanion model for radiotoxic pertechnetate pollutant. Furthermore, a high-throughput screening strategy has been developed based on concentration-gradient design principle to ascertain the process and mechanism for anion exchange. Significantly, a series of intermediates can be successfully isolated as the qualified crystals for single-crystal X-ray diffraction. The result evidently indicates that such a dynamic material will show remarkable breathing effect of the three-dimensional host framework upon anion exchange, which mostly facilitates the anion trapping process. This established methodology will provide a general strategy to discover the internal secrets of complicated solid-state reactions in crystals at the molecular level.

Pore modulation of metal-organic frameworks towards enhanced hydrothermal stability and acetylene uptake via incorporation of different functional brackets

Metal–organic frameworks (MOFs), as a class of adjustable porous crystalline materials, have received considerable attention in recent years. In this study, starting from an unstable MIL-88 type Co(II)-MOF as the prototype structure, two isoreticular stabilized MOFs with similar structural features but different water/thermal stabilities and acetylene sorption behaviors were prepared, which can be modulated by incorporating different functional brackets in the pores. MOF 1 equipped with open metal sites (OMSs) decomposed quickly in water solution, while the free N-donor functionalized MOF 2 could be stable in water with improved thermostability. The gas sorption study reveals that activated material 2 has a significantly enhanced acetylene uptake capacity with a lower Qst value than those of activated 1, showing a 79% increase (242 vs. 135 cm3 g−1) at 273 K and 91% increase (165 vs. 86 cm3 g−1) at 298 K. The acetylene uptake capacity of activated material 2 is extraordinarily high among MOFs without OMSs, and is even comparable to some famous MOFs with much stronger C2H2 binding ability which however require considerably higher energy for regeneration. The experimental results were further confirmed by the molecular mechanics (MM) calculations, grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) studies.

Quest for the Ncb-type Metal–Organic Framework Platform: A Bifunctional Ligand Approach Meets Net Topology Needs

A custom-designed bifunctional ligand was used to connect an in situ formed Co3(OH) cluster affording a porous metal-organic framework, which represents the first case of ncb-type networks constructed from a single kind of ditopic ligand. Noticeably, the activated MOF shows high volumetric C2H2 uptake and excellent adsorption selectivity for C2H2/CO2 separation at room temperature with a low sorption heat.

A CoII-based metal–organic framework based on [Co6(μ3-OH)4] units exhibiting selective sorption of C2H2 over CO2 and CH4

By virtue of unique planar [Co6(μ3-OH)4] cluster units, a new microporous isonicotinate-based framework with high thermal and framework stabilities was achieved. The guest-free framework demonstrates high capacity and selectivity for C2H2 relative to CO2 and CH4 at room temperature, which was further understood by GCMC simulation.

Microporous Cobalt(II)–Organic Framework with Open O-Donor Sites for Effective C2H2 Storage and C2H2/CO2 Separation at Room Temperature

The self-assembly of a bifunctional organic ligand with a formate-bridged rod-shaped secondary building unit leads to a new microporous metal-organic framework (MOF). This MOF shows a moderately high C2H2 storage capacity (145 cm3/g) and an excellent adsorption selectivity for C2H2/CO2 (11) at room temperature. Furthermore, its discriminatory sorption behavior toward C2H2 and CO2 was probed by computational analysis in detail.

Two-Dimensional Zirconium-Based Metal–Organic Framework Nanosheet Composites Embedded with Au Nanoclusters: A Highly Sensitive Electrochemical Aptasensor toward Detecting Cocaine

Two-dimensional (2D) zirconium-based metal-organic framework nanosheets embedded with Au nanoclusters (denoted as 2D AuNCs@521-MOF) were prepared via a one-pot method under mild conditions. The optimized 2D AuNCs@521-MOF nanosheets not only possessed high specific surface area, physicochemical stability, and good electrochemical activity but also exhibited strong bioaffinity toward biomolecule-bearing phosphate groups. Consequently, a large amount of cocaine aptamer strands can be immobilized onto the substrate modified by 2D AuNCs@521-MOF nanosheet, further leading to the formation of a constructed biosensitive platform, which can be used to successfully detect cocaine through the specific binding interactions between cocaine and aptamer strands. The results demonstrated that the 2D AuNCs@521-MOF-based aptasensor had high sensitivity for detecting cocaine within the broad concentration range of 0.001-1.0 ng·mL-1 and the low limit of detection of 1.29 pM (0.44 pg·mL-1) and 2.22 pM (0.75 pg·mL-1) as determined by electrochemical impedance spectroscopy and differential pulse voltammetry, respectively. As expected, with the advantages of high selectivity, repeatability, stability, and simple operation, this new strategy is believed to exhibit great potential for simple and convenient detection of cocaine.