Precise regulating synergistic effect in metal–organic framework for stepwise-controlled adsorption

MAC-20 shows a unique two-step pore-shape change and executes a stepwise-controlled adsorption of dyes mixture in order of their sizes.

Reversible Multiphase Transition in a BioMOF and Its Distinctive Luminescence Turn-On in Alcohol Vapor

Solvothermal reaction of zinc meso-tetra(4-carboxyphenyl)porphyrin and 2,6-diaminopurine with zinc salt in DMF affords a three-dimensional bioMOF (1-α). Its infinite rod-shaped building block features an alternation of octahedral Zn₄O and paddle-wheel Zn₂ clusters bridged by 2,6-diaminopurines. The paddle-wheel Zn₂ cluster undergoes reversible transformation with half into quasi-paddle-wheel Zn₂ cluster and the other half into two tetrahedral mononuclear clusters upon release/uptake of guest molecules, resulting in a new phase 1-β. This single-crystal to single-crystal transformation is accompanied by luminescence on/off switching, possibly associated with the structural conversion between the porphyrin-ligand-based photoactive 1-α and the porphyrin-stacking-caused non-photoactive 1-β. Interestingly, 1-β exhibits quick luminescence turn-on in alcohol vapor instead of other volatile organic solvents by transforming into an intermediate phase 1-γ, which shows a partial luminescence enhancing likely due to the intermittent porphyrin π-π stacking. In view of experimental results and theoretical calculations, this distinctive alcohol-vapor-induced luminescence turn-on is attributed to the coordination ability to porphyrin-bound zinc ion, molecular size, and vapor pressure, in which methanol and ethanol are particularly favored.

Cobalt substitution in a flexible metal-organic framework: modulating a soft paddle-wheel unit for tunable gate-opening adsorption

Developing feasible ways to achieve tunable gate-opening pressure (P_go) while minimizing the side effects on the adsorption capacity and enthalpy is greatly desired for flexible MOFs. In this work, we focused on solving this issue by cobalt substitution. We showed the successful modulation of the energy required for the reversible transformation of a soft paddle-wheel so that the whole framework presented a substitution-dependent P_go for CO₂ adsorption.

Structural Transformations of Amino-Acid-Based Polymers: Syntheses and Structural Characterization

A discrete complex [Zn(tpro)₂(H₂O)₂] (1, Htpro = l-thioproline), and two structural isomers of coordination polymers, a 1D chain of [Zn(tpro)₂]_n (2) and a layered structure [Zn(tpro)₂]_n (3), were synthesized and characterized. The discrete complex 1 undergoes a temperature-driven structural transformation, leading to the formation of a 1D helical coordination polymer 2. Compound 3 is comprised of a 2D homochiral layer network with a (4,4) topology. These layers are mutually linked through hydrogen bonding interactions, resulting in the formation of a 3D network. When 1 is heated, it undergoes nearly complete conversion to the microcrystalline form, i.e., compound 2, which was confirmed by powder X-ray diffractions (PXRD). The carboxylate motifs could be activated after removing the coordinated water molecules by heating at temperatures of up to 150 °C, their orientations becoming distorted, after which, they attacked the activation sites of the Zn(II) centers, leading to the formation of a 1D helix. Moreover, a portion of the PXRD pattern of 1 was converted into the patterns corresponding to 2 and 3, and the ratio between 2 and 3 was precisely determined by the simulation study of in-situ synchrotron PXRD expriments. Consequently, such a 0D complex is capable of underdoing structural transformations and can be converted into 1D and/or 2D amino acid-based coordination polymers.

Larger pores via shorter pillars in flexible layer coordination networks

Metal organic frameworks are porous coordination networks that offer tunable structures via modular synthetic routes. It is well established that zinc 3-amino-1,2,4-triazolate (ATz) forms structures with cationic layers. These layers can be pillared by anions to generate pores. We present three new Zn2(ATz)2(A) structures with A = 1,4-benzenedicarboxylate (BDC) pillars, 2-amino-1,4-benzene-dicarboxylate (BDC-NH2) and 2-methyl-1,4-benzenedicarboxylate (BDC-Me) to give the CALF-24 series of metal organic frameworks. Initially, these compounds were prepared to assess their CO2 capture ability and these data are presented. More significantly, comparing these and published ZnATz relatives, primarily from the group of X.M. Chen, we propose that, for layered systems with some flexibility in their bonding, larger pores actually result by pillaring with shorter linkers. While this may seem counterintuitive, a rationale is offered as borne out by the library of existing data. This offers a general concept for making porous materials based on the rigidity of the building units.

Crystal structure of catena-poly[diaquabis(μ2-3-carboxybenzene-1,2-dicarboxylato-1:2κ2 O:O′)-(μ2-1,4-bis(2-ethylbenzimidazol-1-ylmethyl)-benzene-1:1′κ2 N:N′)dizinc(II)], [Zn2(C26H26N4)(C9H4O6)2(H2O)2]

The structure of C22H19N2O7Zn, has a triclinic(P-1) symmetry. a = 8.1731(16) Å, b = 8.7150(17) Å, c = 15.396(3) Å, α = 75.40(3)°, β = 79.26(3)°, γ = 71.82(3)°, V = 1001.3(3) Å3, Z = 2, R gt (F) = 0.0320, wR ref(F 2) = 0.0768, T = 293(2) K.

Cluster- and chain-based magnetic MOFs derived from 3d metal ions and 1,3,5-benzenetricarboxylate

Three H₃BTC-supported 3D MOFs with triangular M₃ (M = Co, Ni) clusters and rod-shaped sinusoidal-like Mn-chains as building units have been successfully obtained under solvothermal conditions, and complexes 1–3 exhibit antiferromagnetic behaviours.

Construction of a robust pillared-layer framework based on the rare paddlewheel subunit [MnII2(μ-O2CR)4L2]: synthesis, crystal structure and magnetic properties

A robust pillared-layer framework with an α-polonium topology based on the rare paddlewheel subunit [MnII2(μ-O₂CR)₄L₂] is reported. The Mn⋯Mn interaction in it is established by the crystal structure and magnetic measurements.

Predicting and creating 7-connected Zn4O vertices for the construction of an exceptional metal–organic framework with nanoscale cages

A 7-connected Zn₄O unit has been theoretically predicted based on basic zinc acetate [Zn₄O(CH₃COO)₆], which was then experimentally extended into a three-dimensional structure featuring three kinds of nanocage in a unit cell.

Acid-induced Zn(ii)-based metal–organic frameworks for encapsulation and sensitization of lanthanide cations

Two Zn(ii)-based metal–organic frameworks with different coordination geometries have been synthesized and one can effectively capture metal cations and sensitize the visible-emitting Tb³⁺.

A self-catenated rob-type porous coordination polymer constructed from triazolate and carboxylate ligands: fluorescence response to the reversible phase transformation

A flexible MOF, MAC-11, showing photoluminescent response to a phase transformation, has been synthesized and studied.

Connection of zinc paddle-wheels in a pto-type metal–organic framework with 2-methylimidazolate and subsequent incorporation of charged organic guests

2-Methylimidazolate (mIm) connects the Zn₂ paddle-wheels in a pto type framework, leading to an anionic metal–organic framework.

Syntheses, crystal structures, photoluminescent/magnetic properties of four new coordination polymers based on 2,3′,4,5′-biphenyltetracarboxylic acid

Complex 1 is a (4,10)-connected deh1 net. Both complexes 2 and 4 exhibit (4,4)-connected mog moganite nets and novel (3,4,4)-connected networks respectively. Complex 3 is a 3D supermolecular net assembled by 1D anionic chains and cationic chains.

Five Cd(ii) coordination polymers based on 2,3′,5,5′-biphenyltetracarboxylic acid and N-donor coligands: syntheses, structures and fluorescent properties

Five Cd(ii) coordination polymers based on 2,3′,5,5′-biphenyltetracarboxylic acid and different bis(imidazole) ligands have been synthesized.

A three-dimensional chiral crystal structure constructed from a chiral triazolate ligand showing an SrSi2topology: poly[bis(μ3-3,5-diethyl-1,2,4-triazolato-κ3N1:N2:N4)trisilver nitrate]

In the title metal–organic framework (MOF), {[Ag3(C6H10N3)2]NO3}n, the AgIcation is coordinated by two N atoms from two different 3,5-diethyl-1,2,4-triazolate (detz) ligands in a linear configuration. Each AgIcation is then connected to two adjacent AgIcationsviaa μ3-N1:N2:N4-detrz ligand, resulting in a three-dimensional chiral silver–triazolate structure showing an SrSi2(srs) net with 103topology.