Baiyan Li

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.

Introduction of π-Complexation into Porous Aromatic Framework for Highly Selective Adsorption of Ethylene over Ethane

In this work, we demonstrate for the first time the introduction of π-complexation into a porous aromatic framework (PAF), affording significant increase in ethylene uptake capacity, as illustrated in the context of Ag(I) ion functionalized PAF-1, PAF-1-SO3Ag. IAST calculations using single-component-isotherm data and an equimolar ethylene/ethane ratio at 296 K reveal that PAF-1-SO3Ag shows exceptionally high ethylene/ethane adsorption selectivity (Sads: 27 to 125), far surpassing benchmark zeolite and any other MOF reported in literature. The formation of π-complexation between ethylene molecules and Ag(I) ions in PAF-1-SO3Ag has been evidenced by the high isosteric heats of adsorption of C2H4 and also proved by in situ IR spectroscopy studies. Transient breakthrough experiments, supported by simulations, indicate the feasibility of PAF-1-SO3Ag for producing 99.95%+ pure C2H4 in a Pressure Swing Adsorption operation. Our work herein thus suggests a new perspective to functionalizing PAFs and other types of advanced porous materials for highly selective adsorption of ethylene over ethane.

Metal–Organic Framework Based upon the Synergy of a Brønsted Acid Framework and Lewis Acid Centers as a Highly Efficient Heterogeneous Catalyst for Fixed-Bed Reactions

We report a strategy of combining a Brønsted acid metal-organic framework (MOF) with Lewis acid centers to afford a Lewis acid@Brønsted acid MOF with high catalytic activity, as exemplified in the context of MIL-101-Cr-SO3H·Al(III). Because of the synergy between the Brønsted acid framework and the Al(III) Lewis acid centers, MIL-101-Cr-SO3H·Al(III) demonstrates excellent catalytic performance in a series of fixed-bed reactions, outperforming two benchmark zeolite catalysts (H-Beta and HMOR). Our work therefore not only provides a new approach to achieve high catalytic activity in MOFs but also paves a way to develop MOFs as a new type of highly efficient heterogeneous catalysts for fixed-bed reactions.

Metal-Cation-Directed de Novo Assembly of a Functionalized Guest Molecule in the Nanospace of a Metal–Organic Framework

In this work, a new strategy is developed to encapsulate a metal-functionalized guest molecule into a metal-organic framework (MOF) via metal-cation-directed de novo assembly from the component fragments of the guest molecule. This strategy, as illustrated in proof-of-principle studies on the de novo assembly of metal(II) phthalocyanine molecules into bio-MOF-1, can circumvent some drawbacks of existing approaches for encapsulating guest molecules into MOFs, such as inaccessibility for larger guest molecules due to limitations of the MOF window size and disruption of the MOF framework structure by functionalized guest molecules. Overall, this work provides a general yet versatile approach for encapsulating a broader range of metal-functionalized guest molecules into MOFs for various applications.

An N-rich metal–organic framework with an rht topology: high CO2 and C2 hydrocarbons uptake and selective capture from CH4

We report the storage capacities and separation selectivity of an rht-type s-heptazine-based metal organic framework (MOF), [Cu3(TDPAH)(H2O)3]·13H2O·8DMA, 1, (where TDPAH is 2,5,8-tris(3,5-dicarboxylphenylamino)-s-heptazine and DMA is N,N-dimethylacetamide) for C2 hydrocarbons and CO2 over CH4. MOF 1 displays the highest C2H2/CH4 selectivity of 80.9 as well as record high C2H4 and C2H6 adsorption enthalpies. Theoretical calculations reveal that s-heptazine and NH groups within the framework have synergistic effects on CO2 binding.

Coordination polymers constructed by 1,3-bi(4-pyridyl)propane with four different conformations and 2,2′-dinitro-4,4′-biphenyldicarboxylate ligands: the effects of metal ions

Five coordination polymers, [Mn2(NBPDC)2(bpp)]n (1), [Co4(NBPDC)4(bpp)2(H2O)5.25]n (2), [Ni(NBPDC)(bpp)(H2O)2]n (3), [Zn(NBPDC)(bpp)]n (4) and [Cd2(NBPDC)2(bpp)]n (5) (NBPDC = 2,2′-dinitro-4,4′-biphenyldicarboxyl acid, bpp = 1,3-bi(4-pyridyl)propane), have been prepared and structurally characterized. In these compounds, NBPDC and bpp exhibit different coordination modes tuned by different metal ions, and construct various architectures by bridging a variety of inorganic building units. Compound 1 presents a hex net with point symbol for net: {36.418.53.6}. Compound 2 shows a self-penetrating ilc topology by linking Co4 clusters with NBPDC and bpp. Compound 3 presents a 2D structure with (4, 4) topology. Compound 4 shows a diamond network with a 5-fold interpenetrating architecture, featuring left-handed and right-handed helix chains. Compound 5 presents a pcu topology by linking rod-shaped secondary building units. The magnetic properties of compounds 1 and 2 have been characterized.

A new microporous carbon material synthesized via thermolysis of a porous aromatic framework embedded with an extra carbon source for low-pressure CO2 uptake

Pre-introducing an extra carbon source into the porous aromatic framework of PAF-1 followed by thermolysis affords a new microporous carbon material, which demonstrates a CO2 uptake capacity of 93 cm(3) g(-1) (equivalent to 4.1 mmol g(-1) or 18.2 wt%) at 295 K and 1 bar.

High storage capacity and separation selectivity for C2 hydrocarbons over methane in the metal–organic framework Cu–TDPAT

We report on the storage capacity and separation selectivity of an rht-type metal–organic framework, Cu–TDPAT [TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine], for C2 hydrocarbons over CH4. Henrys constant, the isosteric heat of adsorption and the ideal adsorbed solution theory selectivity were calculated based on single-component sorption isotherms. Theoretical calculations indicate that both the open metal sites and the Lewis basic sites have strong interactions with the C2 molecules. The combination of these two kinds of sites lead to the highest C2H2–CH4 selectivity of 127.1 as well as record high values for C2H4 adsorption enthalpies. To mimic real-world conditions, breakthrough experiments were conducted on an equimolar four-component mixture containing C2H2, C2H4, C2H6 and CH4 at room temperature and 1 atm pressure. Our results show that Cu–TDPAT is a promising candidate for CH4 capture and purification.

Bifunctional MOF heterogeneous catalysts based on the synergy of dual functional sites for efficient conversion of CO2 under mild and co-catalyst free conditions

We reported herein a strategy for combining CUS-based MOF (CUS = coordinatively unsaturated metal sites) with ionic liquid (IL) functional sites to form bifunctional heterogeneous catalysts with extra high activity for CO2 fixation. Based on this strategy, two quaternary ammonium salt and quaternary phosphorus salt ionic liquid functionalized CUS-containing MOF heterogeneous catalysts, MIL-101-N(n-Bu)3Br and MIL-101-P(n-Bu)3Br, have been prepared for the first time by a post-synthesis modification method. Due to the synergetic role of dual functional sites including Lewis acid sites in the MOF framwork and Br− ions in the IL functional sites, MIL-101-N(n-Bu)3Br and MIL-101-P(n-Bu)3Br exhibit high catalytic activity for the cycloaddition of CO2 and epoxide under mild and co-catalyst free conditions, which significantly outperforms other benchmark MOF catalysts. Moreover, such bifunctional catalysts can be easily recovered and recycled several times without leaching and loss of activity. Our work thus paves a way for the development of IL functionalized MOFs as heterogeneous catalysts for CO2 fixation.

Design and construction of coordination polymers based on 2,2′-dinitro-4,4′-biphenyldicarboxylate and imidazole-based ligands: The effect of ligand length and metal ions

Five coordination polymers, Mn4(nbpdc)4(bip)(H2O)2 (1), Co5(nbpdc)4(bip)2(H2O)6(OH)2 (2), Cu5(nbpdc)4(bip)2(H2O)2(OH)2 (3), Zn5(nbpdc)4(bip)2(OH)2 (4), and Cd2(nbpdc)2(bip) (5), (H2nbpdc = 2,2′-dinitro-4,4′-biphenyldicarboxyl acid, bip = 1,5-bis(imidazole)pentane), have been prepared and structurally characterized. In these compounds, nbpdc and bip link different secondary building units (SBUs) to construct a variety of architectures based on different metals. Compound 1 presents a 3D hex net based on infinite rod-shaped SBUs. Compound 2 shows a 3D framework with mab topology based on Co5 clusters and exhibits an interesting self-penetration feature. Compound 3 presents a 3D framework with pcu topology constructed by Cu5 clusters. Compound 4 is a 3D framework with pcu topology based on infinite rod-shaped SBUs. Compound 5, like compound 4, also exhibits pcu topology constructed by rod-shaped SBUs, but they both possess different structures. The magnetic properties of compounds 1 and 2 have been characterized.