Compositional control of pore geometry in multivariate metal-organic frameworks: an experimental and computational study

A new approach is reported for tailoring the pore geometry in five series of multivariate metal-organic frameworks (MOFs) based on the structure [Zn-2(bdc)(2)(dabco)] (bdc = 1,4-benzenedicarboxylate, dabco = 1,8-diazabicyclooctane), DMOF-1. A doping procedure has been adopted to form series of MOFs containing varying linker ratios. The series under investigation are [Zn-2(bdc)(2-x)(bdc-Br)(x)(dabco)]center dot nDMF 1 (bdc-Br = 2-bromo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-I)(x)(dabco)]center dot nDMF 2 (bdc-I = 2-iodo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NO2)(x)(dabco)]center dot nDMF 3 (bdc-NO2 = 2-nitro-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NH2)(x)(dabco)]center dot nDMF 4 (bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) and [Zn-2(bdc-Br)(2-x)(bdc-I)(x)(dabco)] nDMF 5. Series 1-3 demonstrate a functionality-dependent pore geometry transition from the square, open pores of DMOF-1 to rhomboidal, narrow pores with increasing proportion of the 2-substituted bdc linker, with the rhomboidal-pore MOFs also showing a temperature-dependent phase change. In contrast, all members of series 4 and 5 have uniform pore geometries. In series 4 this is a square pore topology, whilst series 5 exhibits the rhomboidal pore form. Computational analyses reveal that the pore size and shape in systems 1 and 2 is altered through non-covalent interactions between the organic linkers within the framework, and that this can be controlled by the ligand functionality and ratio. This approach affords the potential to tailor pore geometry and shape within MOFs through judicious choice of ligand ratios

Furnishing Amine-Functionalized Metal–Organic Frameworks with the β-Amidoketone Group by Postsynthetic Modification

The post-synthetic modification (PSM) of amino-functionalized MOFs to those bearing pendant β-amidoketone arms using diketene is herein reported. Three unique MOF families demonstrate the scope of this transformation, which is both atom-economical and yields high conversions. In each case, crystallinity was retained, and instances of exceptional solid-state ordering were observed in the PSM products, which has allowed detailed crystallographic characterization in multiple instances

The Neurotrophic Receptor Ntrk2 Directs Lymphoid Tissue Neovascularization during Leishmania donovani Infection

The neurotrophic tyrosine kinase receptor type 2 (Ntrk2, also known as TrkB) and its ligands brain derived neurotrophic factor (Bdnf), neurotrophin-4 (NT-4/5), and neurotrophin-3 (NT-3) are known primarily for their multiple effects on neuronal differentiation and survival. Here, we provide evidence that Ntrk2 plays a role in the pathologic remodeling of the spleen that accompanies chronic infection. We show that in Leishmania donovani-infected mice, Ntrk2 is aberrantly expressed on splenic endothelial cells and that new maturing blood vessels within the white pulp are intimately associated with F4/80hiCD11bloCD11c+ macrophages that express Bdnf and NT-4/5 and have pro-angiogenic potential in vitro. Furthermore, administration of the small molecule Ntrk2 antagonist ANA-12 to infected mice significantly inhibited white pulp neovascularization but had no effect on red pulp vascular remodeling. We believe this to be the first evidence of the Ntrk2/neurotrophin pathway driving pathogen-induced vascular remodeling in lymphoid tissue. These studies highlight the therapeutic potential of modulating this pathway to inhibit pathological angiogenesis

Compositional control of pore geometry in multivariate metal-organic frameworks: an experimental and computational study

A new approach is reported for tailoring the pore geometry in five series of multivariate metal-organic frameworks (MOFs) based on the structure [Zn-2(bdc)(2)(dabco)] (bdc = 1,4-benzenedicarboxylate, dabco = 1,8-diazabicyclooctane), DMOF-1. A doping procedure has been adopted to form series of MOFs containing varying linker ratios. The series under investigation are [Zn-2(bdc)(2-x)(bdc-Br)(x)(dabco)]center dot nDMF 1 (bdc-Br = 2-bromo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-I)(x)(dabco)]center dot nDMF 2 (bdc-I = 2-iodo-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NO2)(x)(dabco)]center dot nDMF 3 (bdc-NO2 = 2-nitro-1,4-benzenedicarboxylate), [Zn-2(bdc)(2-x)(bdc-NH2)(x)(dabco)]center dot nDMF 4 (bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) and [Zn-2(bdc-Br)(2-x)(bdc-I)(x)(dabco)] nDMF 5. Series 1-3 demonstrate a functionality-dependent pore geometry transition from the square, open pores of DMOF-1 to rhomboidal, narrow pores with increasing proportion of the 2-substituted bdc linker, with the rhomboidal-pore MOFs also showing a temperature-dependent phase change. In contrast, all members of series 4 and 5 have uniform pore geometries. In series 4 this is a square pore topology, whilst series 5 exhibits the rhomboidal pore form. Computational analyses reveal that the pore size and shape in systems 1 and 2 is altered through non-covalent interactions between the organic linkers within the framework, and that this can be controlled by the ligand functionality and ratio. This approach affords the potential to tailor pore geometry and shape within MOFs through judicious choice of ligand ratios

Tuning the Properties of Metal–Organic Frameworks by Post‐synthetic Modification

This chapter introduces the concept of post‐synthetic modification (PSM) in metal–organic framework (MOF) chemistry and provides examples of the use of this technique for a variety of applications. Following a brief introduction (Section 2.1), the different types of PSM reactions are described in Section 2.2. These include covalent transformations to the linker and modification of the inorganic part of the framework through exchange of ligands or metal centers. The next sections concentrate on the use of post‐synthetically modified MOFs for different applications, focusing on gas adsorption and separations (Section 2.3), catalysis (Section 2.4), sequestration and solution phase separations (Section 2.5), and biomedical applications (Section 2.6). In each case the properties of post‐synthetically modified MOFs are compared with those of their non‐modified analogues. Section 2.7 describes systems in which properties are modified through cross‐linking of ligands, and finally, Section 2.8 provides some general conclusions

Tuning the Properties of Metal–Organic Frameworks by Post‐synthetic Modification

This chapter introduces the concept of post‐synthetic modification (PSM) in metal–organic framework (MOF) chemistry and provides examples of the use of this technique for a variety of applications. Following a brief introduction (Section 2.1), the different types of PSM reactions are described in Section 2.2. These include covalent transformations to the linker and modification of the inorganic part of the framework through exchange of ligands or metal centers. The next sections concentrate on the use of post‐synthetically modified MOFs for different applications, focusing on gas adsorption and separations (Section 2.3), catalysis (Section 2.4), sequestration and solution phase separations (Section 2.5), and biomedical applications (Section 2.6). In each case the properties of post‐synthetically modified MOFs are compared with those of their non‐modified analogues. Section 2.7 describes systems in which properties are modified through cross‐linking of ligands, and finally, Section 2.8 provides some general conclusions