Rod MOFs are metal-organic frameworks in which the metal-containing secondary building units consist of infinite rods of linked metal-centered polyhedra. For such materials, we identify the points of extension, often atoms, which define the interface between the organic and inorganic components of the structure. The pattern of points of extension defines a shape such as a helix, ladder, helical ribbon, or cylinder tiling. The linkage of these shapes into a three-dimensional framework in turn defines a net characteristic of the original structure. Some scores of rod MOF structures are illustrated and deconstructed into their underlying nets in this way. Crystallographic data for all nets in their maximum symmetry embeddings are provided.
Reticular chemistry has proven as a notable/distinctive discipline aimed at the deliberate assembly of periodic solids, offering great opportunities to effectively deploy the gained knowledge on net-topologies as a guide and toolbox for designed syntheses, based on the assembly of molecular building blocks into targeted and anticipated structures of crystalline extended solids. The effective practice of reticular chemistry has enriched the repertoire of crystal chemistry and afforded the notable accelerating development of crystalline extended frameworks, especially metal-organic frameworks (MOFs). Here, we review a special class of trinodal MOF structures based on the reticulation of special minimal edgetransitive nets (nets with transitivity [3 2], three distinct nodes and two kind of edges) derived from edge-transitive nets (one kind of edge). The rationale for deriving these special minimal edge-transitive nets is reviewed and their associated net-coded building (net-cBUs) for the design of trinodal MOFs is presented and discussed. The resultant inclusive list of the enumerated minimal edge-transitive nets provides a unique toolbox for the material's designer as it offers ideal blueprints for the deliberate design and rational assembly of building blocks with embedded multiple branch points into intricate trinodal MOFs.
A supramolecular dual emissive system incorporating two classical copper(I)-cluster-based luminophores, namely, Cu(4)I(4) and Cu(3)Pz(3) (Pz = pyrazolate), is reported. The targeted luminescent coordination polymer exhibits reversible thermochromism spanning from green to orange-red.
Two classical copper(I)-cluster-based luminophores, namely, Cu4I4 and [Cu3Pz3]2 (Pz = pyrazolate), are immobilized in a supramolecular system through the formation of metal-organic framework (MOF) materials. This series of luminescent MOF materials, namely, [Cu4I4(NH3)Cu3(L1)3]n, [Cu4I4(NH2CH3)Cu3(L1)3]n, and [Cu4I4Cu3(L2)3]n (L1 = 3-(4-pyridyl)-5-(p-tolyl)pyrazolate; L2 = 3-(4-pyridyl)-5-(2,4-dimethylphenyl)pyrazolate), exhibit diverse thermochromism attributed to the relative functioning efficacy of the two coordination luminophores. Such an intriguing chemopalette effect is regulated by the different supramolecular microenvironments between the two-dimensional layers of these MOFs, and in particular, by the fine-tuned Cu-Cu distances in the excimeric [Cu3Pz3]2 luminophore. The structure-property elucidation of the thermochromic behavior allows one to understand these optical materials with unusual dual-emissive properties.
A novel hydrophobic metal-organic framework (MOF), namely Cu2 L (L = 3,3',5,5'-tetraethyl-4,4'-bipyrazolate), is synthesized through a stepwise method, and exhibits an unprecedented 3,4-c net. The exceptionally thermal, chemical, and air stability of this MOF, especially in water and under acidic or basic conditions, and its selective and fast sorption capacity for hydrocarbons over water warrant its direct use for efficient removal of trace organic wastes (e.g. benzene, toluene, xylene, and mixtures thereof) from contaminated water.
Chromium(III)-based metal-organic frameworks (Cr-MOFs) are very attractive in a wide range of investigations because of their robustness and high porosity. However, reports on Cr-MOFs are scarce owing to the difficulties in their direct synthesis. Recently developed postsynthetic routes to obtain Cr-MOFs suffered from complicated procedures and a lack of general applicability. Herein, we report a highly efficient and versatile strategy, namely solvent-assisted metal metathesis, to obtain Cr-MOFs from a variety of Fe -MOFs, including several well-known MOFs and a newly synthesized one, through judicious selection of a coordinating solvent. The versatility of this strategy was demonstrated by producing Cr-MIL-100, Cr-MIL-142A/C, Cr-PCN-333, and Cr-PCN-600 from their Fe analogues and Cr-SXU-1 from a newly synthesized MOF precursor, Fe-SXU-1, in acetone as the solvent under very mild conditions. We have thus developed a general approach for the preparation of robust Cr-MOFs, which are difficult to synthesize by direct methods.
Biological and artificial molecules and assemblies capable of supramolecular recognition, especially those with nucleobase pairing, usually rely on autonomous or collective binding to function. Advanced site-specific recognition takes advantage of cooperative spatial effects, as in local folding in protein-DNA binding. Herein, we report a new nucleobase-tagged metal-organic framework (MOF), namely ZnBTCA (BTC=benzene-1,3,5-tricarboxyl, A=adenine), in which the exposed Watson-Crick faces of adenine residues are immobilized periodically on the interior crystalline surface. Systematic control experiments demonstrated the cooperation of the open Watson-Crick sites and spatial effects within the nanopores, and thermodynamic and kinetic studies revealed a hysteretic host-guest interaction attributed to mild chemisorption. We further exploited this behavior for adenine-thymine binding within the constrained pores, and a globally adaptive response of the MOF host was observed.
Reported here are three 3D metal-organic framework (MOF) polymorphs with the chemical formula [Fe(2)(H(0.67)bdt)(3)]·xH(2)O (H(2)bdt = 5,5'-(1,4-phenylene)bis(1H-tetrazole)), all of which are constructed from similar Fe(II)-tetrazole rod secondary building units (SBUs) via covalent links, but exhibit diverse spin states regulated by inter-chain cooperativity.
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