Metal-organic Framework Building Research Articles

Site-specific anisotropic assembly of amorphous mesoporous subunits on crystalline metal–organic framework

As an important branch of anisotropic nanohybrids (ANHs) with multiple surfaces and functions, the porous ANHs (p-ANHs) have attracted extensive attentions because of the unique characteristics of high surface area, tunable pore structures and controllable framework compositions, etc. However, due to the large surface-chemistry and lattice mismatches between the crystalline and amorphous porous nanomaterials, the site-specific anisotropic assembly of amorphous subunits on crystalline host is challenging. Here, we report a selective occupation strategy to achieve site-specific anisotropic growth of amorphous mesoporous subunits on crystalline metal–organic framework (MOF). The amorphous polydopamine (mPDA) building blocks can be controllably grown on the {100} (type 1) or {110} (type 2) facets of crystalline ZIF-8 to form the binary super-structured p-ANHs. Based on the secondary epitaxial growth of tertiary MOF building blocks on type 1 and 2 nanostructures, the ternary p-ANHs with controllable compositions and architectures are also rationally synthesized (type 3 and 4). These intricate and unprecedented superstructures provide a good platform for the construction of nanocomposites with multiple functionalities and understanding of the structure-property-function relationships.

Integrated metal‐organic framework (MOF) and pressure/vacuum swing adsorption process design:MOFmatching

AbstractA two‐step integrated metal‐organic framework (MOF) and pressure/vacuum swing adsorption (P/VSA) process design has been recently established for gas separation. In the first step, selected MOF descriptors and process operating conditions are simultaneously optimized to maximize the process performance. Based on the obtained results, the second step (i.e., MOF matching) is addressed and exemplified by propene/propane separation in this work. Computational MOF synthesis and screening are explicitly carried out to find new advanced material candidates for enhancing the separation process efficiency. First, model‐based property‐performance relationships are developed for fast MOF screening. Then, MOF building blocks are extracted from 471 MOFs contained in the Computation‐Ready Experimental (CoRE) MOF database. With these building blocks, 45,472 hypothetical MOFs are created. After model‐based and molecular simulation‐based screening, six candidates are left and sent to P/VSA process optimization. Finally, three candidates are found to meet the predefined separation specifications and one candidate shows a better process performance than the best out of the 471 CoRE MOFs.

Proton Conduction in Two Highly Stable Cadmium(Ii) Metal-Organic Frameworks Built by Substituted Imidazole Dicarboxylates

Proton Conduction in Two Highly Stable Cadmium(Ii) Metal-Organic Frameworks Built by Substituted Imidazole Dicarboxylates

Induction of Chirality in a Metal-Organic Framework Built from Achiral Precursors.

Induction of chirality from an achiral assembly system remains a huge challenge related to the origin of life. Here, induction of chirality in a metal-organic framework (MOF) built from achiral precursors has been realized. Assembling achiral H3 BTB ligands and ZnII /CdII clusters leads to a 2D coordination polymer (FJI-H16), while introduction of achiral pyridine into such assembly system leads to a 3D chiral MOF (FJI-H27 (M) or (P)). The driven force for chiral generation has been proved to be a pyridine participated kinetic-control assembly process, which can be controlled by changing the amount of pyridine and temperature, from no induction to partial induction to complete induction. The chiral generation process has been identified in detail through a pyridine-involved key intermediate (FJI-H28). The targeted modification of pyridine can selectively lead to FJI-H27 (M) or FJI-H27 (P), making the chiral orientation and distribution of bulk FJI-H27 samples can be controlled. Our work not only represents a new chiral induction process that may relate to the chiral origin in nature, but also firstly reveals how achiral external stimuli generate chirality from achiral precursors, and offers a guide for rational preparation of chiral MOFs.

Induction of Chirality in a Metal–Organic Framework Built from Achiral Precursors

AbstractInduction of chirality from an achiral assembly system remains a huge challenge related to the origin of life. Here, induction of chirality in a metal–organic framework (MOF) built from achiral precursors has been realized. Assembling achiral H3BTB ligands and ZnII/CdII clusters leads to a 2D coordination polymer (FJI‐H16), while introduction of achiral pyridine into such assembly system leads to a 3D chiral MOF (FJI‐H27 (M) or (P)). The driven force for chiral generation has been proved to be a pyridine participated kinetic‐control assembly process, which can be controlled by changing the amount of pyridine and temperature, from no induction to partial induction to complete induction. The chiral generation process has been identified in detail through a pyridine‐involved key intermediate (FJI‐H28). The targeted modification of pyridine can selectively lead to FJI‐H27 (M) or FJI‐H27 (P), making the chiral orientation and distribution of bulk FJI‐H27 samples can be controlled. Our work not only represents a new chiral induction process that may relate to the chiral origin in nature, but also firstly reveals how achiral external stimuli generate chirality from achiral precursors, and offers a guide for rational preparation of chiral MOFs.

Front Cover: A Microporous Co(II)‐Based 3‐D Metal Organic Framework Built from Magnetic Infinite Rod‐Shaped Secondary Building Units (Eur. J. Inorg. Chem. 38/2019)

Front Cover: A Microporous Co(II)‐Based 3‐D Metal Organic Framework Built from Magnetic Infinite Rod‐Shaped Secondary Building Units (Eur. J. Inorg. Chem. 38/2019)

A Microporous Co(II)‐Based 3‐D Metal Organic Framework Built from Magnetic Infinite Rod‐Shaped Secondary Building Units

AbstractInvited for the cover of this issue is Anastasios Tasiopoulos from the University of Cyprus. The cover image shows photos from the southwestern Cyclades island group of the Aegean Sea, which contain a wealth of minerals and rocks. Some of these exhibit porous structures and interesting magnetic properties.

A Microporous Co(II)‐Based 3‐D Metal Organic Framework Built from Magnetic Infinite Rod‐Shaped Secondary Building Units

The synthesis and characterization of {[Co5(INA)3(HCOO)7(DMF)(H2O)]·2DMF·4H2O}∞ (INA– = the anion of isonicotinic acid) denoted as Co5‐INA·2DMF·4H2O is reported. The compound was isolated from the reaction of Co(NO3)2·6H2O with HINA in the presence of HCOOH in N,N‐dimethylformamide (DMF) at 100 °C. It exhibits a rigid 3‐D porous structure based on Co5 repeating units which are linked through carboxylate ligands (from HCOO– and INA–) to form an infinite rod‐shaped secondary building unit (SBU). The rods are connected through isonicotinate ligands to produce a unique (3,3,4,4,4‐coordinated) 5‐nodal 3D network with point symbol (4.5.6.72.9)(4.5.62.7.8)(4.5.7)2(5.62.73). Gas sorption studies revealed that Co5‐INA displays a microporous structure with BET area 264.5 m2 g–1 and CO2 uptake of 1.96/1.29 mmol·g–1 at 273/298 K (1 bar), respectively. Magnetism studies revealed that Co5‐INA displays spin canting behavior with a spin glass relaxation process at ca. 5.0 K.

Direct, One-Pot Syntheses of MOFs Decorated with Low-Valent Metal-Phosphine Complexes

We demonstrate a simple and generalizable method for the one pot, in situ formation of bimetallic metal–organic framework (MOF) materials decorated with crystallographically defined, low-valent metal sites. Solvothermal reactions between poly(carboxylated) aryl(phosphine) ligands and mixtures of higher- and lower-valent metal precursors achieves concomitant P–M complexation and MOF formation via metal–carboxylate network bonding. This method is demonstrated in the preparation of two new phosphine coordination materials, PCM-107 and PCM-74, which feature Ar3P–AuX (X = Cl, Br) and chelated PN–Cu2I2–PN units as the MOF building blocks, respectively. PCM-107 is an active catalyst for alkyne hydroaddition, while PCM-74 shows promise for the crystallization of MOFs bearing kinetically favored isomers.

Ultra‐microporous Metal–Organic Framework Built from Rigid Linkers Showing Structural Flexibility Resulting in a Marked Change in Carbon Dioxide Capacity

An ultra‐microporous CoHAtzOx (HAtz = aminotriazole, Ox = oxalate) metal–organic framework with a 3D framework showing guest‐dependent reversible structural transformations was studied. The flexibility was found to arise from buckling of the rigid Co–Ox and Co–HAtz chains, which yields a desolvated structure with a 78 % lower void volume and significantly lower CO2 capacity.

Water–alkane interface promotes the formation of metal–organic frameworks

To develop facile, rapid and low-energy route for metal–organic framework (MOF) formation is of great importance. Here a water–alkane interface strategy was proposed for the MOF formation at room temperature. The content and molecular structure of alkane phase were found to have remarkable effect on regulating the porosity properties of MOFs. For example, the MOF synthesized in 1:1 (v/v) water/n-hexane mixture has the largest BET surface area (1474.1 m2/g) and total pore volume (0.7030 cm3/g). The mechanism was discussed from the competitive adsorption of water and alkane in the micropores of MOF building blocks during formation process.

Metal–Organic Frameworks Built from a Linear Rigid Dicarboxylate and Different Colinkers: Trap of the Keto Form of Ethylacetoacetate, Luminescence and Ferroelectric Studies

The ligand 2,6,2′,6′-tetranitro-biphenyl-4,4′-dicarboxylic acid (H2L) has been used alone or with a coligand to construct a number of metal organic frameworks (MOFs) with different metal ions that are X-ray crystallographically characterized. The porous three-dimensional (3D) MOF {[Gd2(L)3(DMF)4]·(4DMF)·(3H2O)}n (1) (DMF = N,N′-dimethylformamide) is found to be an excellent host to the keto form of ethylacetoacetate to produce {[Gd(L)1.5(DMF)2(H2O)2](S)(H2O)}n (1a) (S = ethyl 3-oxobutanoate) in single crystal to single crystal (SC–SC) transformation. This involves drastic rearrangement of the channels including several carboxylate shifts and concomitant movement of water molecules from the cavity to the metal center. Interestingly, the daughter framework 1a reverts back to the mother framework 1 upon keeping it in DMF for 3 days at room temperature, suggesting that the framework 1 can be used as a container. The linker H2L also forms the MOFs {[(Cd)4(L)3(HlL1)2(DMF)(H2O)2](DMF)3(H2O)2}n (2), {[Cd(L)(L2)]}...

Engineering New Metal-Organic Frameworks Built from Flexible Tetrapyridines Coordinated to Cu(II) and Cu(I)

A series of new metal-organic frameworks have been constructed by the coordination of Cu(II) and Cu(I) with pentaerythrityl tetrakis(4-pyridyl) ether (1 = PETPE), a flexible tetradentate ligand. Networks derived from Cu(OOCCH(3))(2), Cu(NO(3))(2), and CuBF(4) proved to have different topologies (diamondoid, PtS, and SrAl(2), respectively). This reflects (1) the ability of PETPE (1) to adopt diverse conformations and (2) the varied geometries of complexes of Cu(II) and Cu(I). Extended PETPE (2), a tetrapyridine with phenyl spacers inserted into the pentaerythrityl core of PETPE (1), yielded an expanded version of the PtS network derived from simple PETPE (1) and Cu(NO(3))(2). However, increases in the ability of the network to accommodate guests were largely offset by interpenetration of independent networks. Attempts to thwart interpenetration by converting ligand 2 into methyl-substituted derivative 3 led to the construction of networks with alternative topologies. In particular, the reactions of ligand 3 with both Cu(II) and Cu(I) yielded isostructural Pt(3)O(4) networks, despite the preference of the two oxidation states for coordination spheres with different geometries. Together, these observations demonstrate that PETPE (1) and related compounds are useful ligands for constructing metal-organic frameworks, with a distinctive ability to accommodate a single metal in different oxidation states, as well as to adapt to a metal in a single oxidation state but with different counterions or secondary ligands.