Haohan Wu

Enhanced Binding Affinity, Remarkable Selectivity, and High Capacity of CO2 by Dual Functionalization of a rht‐Type Metal–Organic Framework

This work was supported by the Foundation of the National Natural Science Foundation of China (grant numbers 20971054 and 90922034) and the Key Project of the Chinese Ministry of Education. The RU and UTD teams would like to acknowledge support from DOE (grant number DE-FG02-08ER46491). We thank Prof. Xianhe Bu and Dr. Ze Chang (Nankai University, China) and Dr. Ruiping Chen (Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences) for part of the gas adsorption measurements.

A Multifunctional 3D Ferroelectric and NLO-Active Porous Metal-Organic Framework

The tetracarboxylate organic linker and Zn(II) ions assemble into chiral building blocks for a porous metal-organic framework with ferroelectric and second-order nonlinear optical properties.

Enhancing gas adsorption and separation capacity through ligand functionalization of microporous metal-organic framework structures

Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials.

In situ tetrazole ligand synthesis leading to a microporous cadmium–organic framework for selective ion sensing

In situ tetrazole ligand synthesis leads to a luminescent microporous cadmium-organic framework {[Cd(mu2-Cl)(mu4-5MT)]n (5MT = 5-methyl-1H-tetrazole)} that exhibits a high-sensitivity sensing function with respect to nitrite in both DMF and water.

A flexible MMOF exhibiting high selectivity for CO2 over N2, CH4 and other small gases

A flexible microporous metal organic framework structure, [Zn(2)(bpdc)(2)bpe]·2DMF, exhibits high selectivity in adsorbing CO(2) over N(2), CH(4) and a number of other small gases at room temperature and low pressure.

ℝPM3: A Multifunctional Microporous MOF with Recyclable Framework and High H2 Binding Energy†

A microporous metal organic framework structure, Zn(2)(bpdc)(2)(bpee).2DMF (DMF: N,N-dimethylformamide), has been synthesized via solvothermal reactions. The compound is a new member of the RPM series (RPM = Rutgers Recyclable Porous Material) that possesses a flexible and recyclable three-dimensional framework containing one-dimensional channels. It exhibits interesting and multifold functionality, including porosity, commensurate adsorption for hydrocarbons, high hydrogen binding energy (determined by isosteric heats of hydrogen adsorption and confirmed by van der Waals density functional calculations) as a result of multifold binding to aromatic ligands (determined by IR spectroscopy), strong photoluminescence emission, and reversible fluorescence quenching properties.

Anionic Gallium-Based Metal−Organic Framework and Its Sorption and Ion-Exchange Properties

A gallium-based metal-organic framework Ga(6)(C(9)H(3)O(6))(8)·(C(2)H(8)N)(6)(C(3)H(7)NO)(3)(H(2)O)(26) [1, Ga(6)(1,3,5-BTC)(8)·6DMA·3DMF·26H(2)O], GaMOF-1; BTC = benzenetricarboxylate/trimesic acid and DMA = dimethylamine], with space group I43d, a = 19.611(1) Å, and V = 7953.4(6) Å(3), was synthesized using solvothermal techniques and characterized by synchrotron-based X-ray microcrystal diffraction. Compound 1 contains isolated gallium tetrahedra connected by the organic linker (BTC) forming a 3,4-connected anionic porous network. Disordered positively charged ions and solvent molecules are present in the pore, compensating for the negative charge of the framework. These positively charged molecules could be exchanged with alkali-metal ions, as is evident by an ICP-MS study. The H(2) storage capacity of the parent framework is moderate with a H(2) storage capacity of ~0.5 wt % at 77 K and 1 atm.

Spectroscopic characterization of van der Waals interactions in a metal organic framework with unsaturated metal centers: MOF-74-Mg.

The adsorption energies of small molecules in nanoporous materials are often determined by isotherm measurements. The nature of the interaction and the response of the host material, however, can best be studied by spectroscopic methods. We show here that infrared absorption and Raman spectroscopy measurements together with density functional theory calculations, utilizing the novel van der Waals density functional vdW-DF, constitute a powerful approach to studying the weak van der Waals interactions associated with the incorporation of small molecules in these materials. In particular, we show how vdW-DF assists the interpretation of the vibrational spectroscopy data to uncover the binding sites and energies of these molecules, including the subtle dependence on loading of the IR asymmetric stretch mode of CO(2) when adsorbed in MOF-74-Mg. To gain a better understanding of the adsorption mechanism of CO(2) in MOF-74-Mg, the results are compared with CO within MOF-74-Mg.

Encapsulated recyclable porous materials: an effective moisture-triggered fragrance release system

A moisture-triggered release system was developed using porous metal-organic materials as encapsulating agents. Release of both hydrophilic (ethyl butyrate) and hydrophobic (D-limonene) fragrance compounds was investigated by gas adsorption measurement, thermogravimetric analysis and gas chromatography-mass spectroscopy. These materials exhibit exceptional fragrance compatibility and controlled release compared to the current leading encapsulation technology.