Design, synthesis, and control of metrics, functionality, and interpenetration in metal -organic frameworks and their application in hydrogen storage.

This thesis reports the isolation of both the interpenetrated [Zn4O(TPDC)3•(DEF)(H2O)5 (IRMOF-15)] and non-interpenetrated [Zn4O(TPDC)3•(DEF) 17(H2O)2 (IRMOF-16)] forms of identical frameworks, demonstrating for the first time that interpenetration can be avoided even when it is topologically allowed. Additionally, a second series of frameworks, MOF-69A-C [Zn3(BPDC)2(OH)2•(DEF) 2(H2O)2 (MOF-69A), Zn3(OH)2(2,6-NDC) 2•(DEF)2(H2O)2 (MOF-69B), and Zn3(OH)2(BDC)2•(DEF)2(H 2O)2 (MOF-69C)] was synthesized. The unique aspect of these frameworks is the presence of rod building units that result in an underlying framework topology that forbids interpenetration, regardless of linker length. Rod building units were also identified in MOFs-71-73 [Co(BDC)(DMF) (MOF-71), Mn1.5(BDC)1.5(DEF) (MOF-72), Cd3(1,3-BDC) 4•(Me2NH2)2 (MOF-73)]. Coupled with MOF-69A-C, MOFs-71-73 prompted consideration of new design strategies for the construction of stable, porous MOFs based on rod building units. Sorption studies indicate that MOF-72 is a microporous material, proving that rod-based MOF assemblies can indeed be highly stable. This thesis also presents a study that relates SBU dimension to pH of reaction and shows specifically that the dimension of the SBU can increase with increasing pH. The description of Zn3(1,4-BDC)4•(DEF) 2(Et2NH2)2(Et2NH)1.5 (MOF-144) is detailed in these studies. In addition, this thesis uses knowledge of SBU formation to design MOFs with functionalized links: Zn 3(TCPP)(H2O)2(DEF)2•(DEF) 11(H2O)11 (MOF-122) is the first microporous MOF that contains a porphyrin linker and Zn4O(C26H 18O4)3•(DEF)14(H2O) 13.5 (IRMOF-17) is one of the first examples of a designed homochiral 3-D MOF. Finally, inelastic neutron scattering spectroscopy of hydrogen sorbed Zn4O(C8H4O4)3 (MOF-5) was used to identify the interactions between the adsorbed hydrogen molecules and the framework. It was found that favorable interactions exist between the adsorbed hydrogen and both the framework zinc atoms and the 1,4-benzenedicarboxylate linkers (C8H4O4). Moreover, it was shown that the linkers contain several hydrogen binding sites. It was then shown that Zn4O(C12H6O4)3 (IRMOF-8), which has a larger naphthalene linker, has quadruple the hydrogen uptake of MOF-5 (2.0 wt. %) at room temperature and 10 bar.Ph.D.Inorganic chemistryPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/123687/2/3096186.pd

Design and Preparation of a Core–Shell Metal–Organic Framework for Selective CO₂ Capture

The design of a core–shell metal–organic framework comprising a porous <b>bio-MOF-11/14</b> mixed core and a less porous <b>bio-MOF-14</b> shell is reported. The growth of the MOF shell was directly observed and supported by SEM and PXRD. The resulting core–shell material exhibits 30% higher CO₂ uptake than <b>bio-MOF-14</b> and low N₂ uptake in comparison to the core. When the core–shell architecture is destroyed by fracturing the crystallites via grinding, the amount of N₂ adsorbed doubles but the CO₂ adsorption capacity remains the same. Finally, the more water stable <b>bio-MOF-14</b> shell serves to prevent degradation of the water-sensitive core in aqueous environments, as evidenced by SEM and PXRD

Ship-in-a-Bottle Preparation of Long Wavelength Molecular Antennae in Lanthanide Metal–Organic Frameworks for Biological Imaging

International audienceWhile metal–organic frameworks (MOFs) have been identified as promising materials for sensitizing near-infrared emitting lanthanide ions (Ln3+) for biological imaging, long-wavelength excitation of such materials requires large, highly delocalized organic linkers or guest-chromophores. Incorporation of such species generally coincides with fewer Ln3+ emitters per unit volume. Herein, the excitation bands of ytterbium-based MOFs are extended to 800 nm via the postsynthetic coupling of acetylene units to form a high density of conjugated π-systems throughout MOF pores. The resulting long wavelength excitation/absorption bands are a synergistic property of the composite material as they are not observed in the individual organic components after disassociation of the MOFs, thus circumventing the need for large organic chromophores. We demonstrate that the long wavelength excitation and emission properties of these modified MOFs are maintained in the biological conditions of cell culture (aqueous environment, salts, heating), pointing toward their promising use for biological imaging applications

One Approach for Two: Toward the Creation of Near-Infrared Imaging Agents and Rapid Screening of Lanthanide(III) Ion Sensitizers Using Polystyrene Nanobeads

International audienceThe unique luminescence properties of lanthanide(III) ions (Ln3+) in the near-infrared (NIR) range are attracting major attention in view of their exciting applications in the fields of technology, telecommunications, biology, and medicine. One of the main strategies to design luminescent Ln3+-based compounds relies on their sensitization through appropriate chromophoric ligands. The choice of the chromophores depends on the nature of Ln3+ and, as of today, still partially requires experimental trials, in particular, for the creation of luminescent compounds incorporating NIR-emitting Ln3+. The synthesis of organic ligands bearing suitable coordinating and chromophoric units is time- and effort-consuming. We have established a strategy to encapsulate a large number of Yb3+ trifluoromethanesulfonates and 1,n-dihydroxyanthraquinone chromophores in NH2-functionalized 100 nm polystyrene (PS) beads through a rapid swelling process, leading to AQ1,nOH-Yb@PS/NH2 (n = 4, 8). We have shown that 1,n-dihydroxyanthraquinones can act as antennae and sensitize the characteristic Yb3+ emission in the NIR upon excitation at 465 nm. To validate the bioapplicability of these luminescent beads, polyethylene glycol (PEG)-coated beads have been prepared (AQ1,nOH-Yb@PS/PEG) and demonstrated to be noncytotoxic for HeLa cells up to 500 μg/mL. Confocal microscopy experiments have shown that AQ1,nOH-Yb@PS/PEG is taken up by HeLa cells, whereas epifluorescence microscopy confirmed the possibility of detecting the NIR Yb3+ emission in living cells. The developed strategy has a high potential and can be further applied for the rapid screening of sensitizers for different NIR-emitting Ln3+ ions and for the creation of smart NIR-emitting imaging agents

Near infrared excitation and emission in rare earth MOFs via encapsulation of organic dyes

International audienceWe successfully demonstrate that metal–organic frameworks (MOFs) can be designed to be excited and emit within the biological diagnostic window (650–1450 nm). An isoreticular series of anionic rare earth MOFs with fcu topology was synthesized using 10 different rare earth elements (Y3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+) and common linear ditopic ligands. Five different cationic dye molecules were incorporated into the MOFs via ion exchange. When LDS 750, which exhibits low-energy absorption in the range 450–770 nm, is loaded into an Yb3+-MOF, it can be used as an antenna to sensitize the near-infrared (NIR) emission of Yb3+ centred at 980 nm

Systematic Adjustment of Pitch and Particle Dimensions within a Family of Chiral Plasmonic Gold Nanoparticle Single Helices

Systematically controlling the assembly architecture within a class of chiral nanoparticle superstructures is important for fine-tuning their chiroptical properties. Here, we report a family of chiral gold nanoparticle single helices, varying in helical pitch and nanoparticle dimensions, that is assembled using a series of peptide conjugate molecules C_<i>x</i>-(PEP_Au^M‑ox)₂ (PEP_Au^M‑ox = AYSSGAPPM^oxPPF; <i>x</i> = 16–22). We demonstrate that the aliphatic tail length (i) can be used as a handle to systematically tune the helical pitch from 80 to 130 nm; and (ii) influences the size, shape, and aspect ratio of the component nanoparticles. Certain members of this family of materials exhibit intense plasmonic chiroptical activity. These studies highlight the multiple levels of structural control that can be achieved within a class of chiral nanoparticle superstructures via careful design and selection of peptide conjugate precursor

Near-infrared emitting ytterbium metal–organic frameworks with tunable excitation properties

International audienceThe design of metal-organic frameworks (MOFs) incorporating near-infrared emitting ytterbium cations and organic sensitizers allows for the preparation of new materials with tunable and enhanced photophysical properties

Zinc-Adeninate Metal-Organic Framework for Aqueous Encapsulation and Sensitization of Near-infrared and Visible Emitting Lanthanide Cations

International audienceLuminescent metal-organic frameworks (MOFs), Ln(3+)@bio-MOF-1, were synthesized via post-synthetic cation exchange of bio-MOF-1 with Tb3+, Sm3+, Eu3+, or Yb3+, and their photophysical properties were studied. We demonstrate that bio-MOF-1 encapsulates and sensitizes visible and near-infrared emitting lanthanide cations in aqueous solution

Rare Earth pcu Metal–Organic Framework Platform Based on RE 4 (μ 3 -OH) 4 (COO) 6 2+ Clusters: Rational Design, Directed Synthesis, and Deliberate Tuning of Excitation Wavelengths

International audienceThe Td point group symmetry of rare earth (RE3+) metal clusters RE4(mu3-OH)4(COO)62+ makes them attractive building blocks for creating metal-organic frameworks (MOFs) with controllable topologies. Herein, we describe the design and synthesis of a series of isoreticular MOFs featuring pcu topology [MOF-1114(RE) and MOF-1115(RE)] with variable rare earth metal ions (RE3+ = Y3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) and linear amino-functionalized dicarboxylate linkers of different lengths. In total, we report 22 MOFs that vary in both composition and structure yet share the same RE4(mu3-OH)4 cluster motif. We demonstrate that these pcu MOFs are cationic and that anion exchange can be used to affect the MOF properties. We also investigate the luminescence properties of a representative member of this MOF series [MOF-1114(Yb)] that exhibits near-infrared emission. We show that the excitation energy for Yb3+ sensitization can be carefully adjusted to lower energy via covalent postsynthetic modification at the amino group sites within the MOF