Crystalline central-metal transformation in metal-organic frameworks

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.

A Sr2+-metal-organic framework with high chemical stability: synthesis, crystal structure and photoluminescence property

Metal-organic frameworks (MOFs) are typically built by assembly of metal centres and organic linkers, and have emerged as promising crystalline materials in a variety of fields. However, the stability of MOFs is a key limitation for their practical applications. Herein, we report a novel Sr 2+: -MOF [Sr₄(Tdada)₂(H₂O)₃(DMF)₂] (denoted as NKU- 105: , NKU = Nankai University; H₄Tdada = 5,5'-((thiophene-2,5-dicar bonyl)bis(azanediyl))diisophthalic acid; DMF = N,N-dimethylformamide) featuring an open square channel of about 6 Å along the c-axis. Notably, NKU- 105: exhibits much outstanding chemical stability against common organic solvents, boiling water, acids and bases, relative to most MOF materials. Furthermore, NKU- 105: is an environment-friendly luminescent material with a bright cyan emission.This article is part of the themed issue 'Coordination polymers and metal-organic frameworks: materials by design'.

Design and synthesis of coordination polymers with chelated units and their application in nanomaterials science

The advances and problems associated with the preparation, properties and structure of coordination polymers with chelated units are presented and assessed.

Synthesis of bimetallic Zr(Ti)-naphthalendicarboxylate MOFs and their properties as Lewis acid catalysis

Bimetallic Zr(Ti)-NDC based metal–organic frameworks (MOFs) have been prepared by incorporation of titanium(iv) into zirconium(iv)-NDC-MOFs (UiO family).

Metal-center exchange of tetrahedral cages: single crystal to single crystal and spin-crossover properties

Effective SCSC metal-center exchange was observed in a tetrahedral metal–organic cage, in which the metal centers can be induced to display spin crossover behaviors.

Dual structure evolution of a Ag(i) supramolecular framework triggered by anion-exchange: replacement of terminal ligand and switching of network interpenetration degree

Dual single-crystal to single-crystal transformations triggered by different anion-exchanges are achieved for a Ag(i) coordination framework, where switching of network interpenetration degree is observed.