X-ray crystallographic analysis of ADORable zeolites and metal-organic frameworks

This thesis largely focuses on the mechanistic analysis of the Assembly-Disassembly- Organisation-Reassembly (ADOR) process through a range of crystallographic techniques including powder X-ray diffraction and Pair Distribution Function (PDF) analysis and subsequent analysis using solid-state kinetics. Chapter 4 describes the development of a new standard protocol to using the ADOR process. The protocol describes the development of a procedure used for identifying the optimum conditions (time of reaction, temperature, acidity, etc.) for the ADOR process. In developing the protocol, Ge-containing UTL zeolites were subjected to hydrolysis conditions using both water and hydrochloric acid as media, which provides an understanding of the effects of temperature and pH on the Disassembly (D) and Organisation (O) steps of the process that define the potential products. Samples were analysed by powder X-ray diffraction to yield a time course for the reaction at each set of conditions. Chapter 5 continues work on the ADOR process and presents the first kinetic study on the two most prominent steps in the process; Disassembly and Organisation. By using solid- state kinetic models, Avrami-Erofeev and its linear equivalent Sharp-Hancock, the dependence on temperature and presence of liquid water was investigated and the activation energy of the rearrangement process quantified. Work on the rearrangement step aimed to understand where the silica species intercalates from and which material formed as the kinetic and thermodynamic product from the reaction. Chapter 6 describes a study into the Disassembly and Organisation steps of the ADOR process through in situ Pair Distribution Function (PDF) analysis. This hopes to shed light on the selectivity of the ADOR process in different media and the mechanism by which the double-four-ring (d4r) breakdown. On a different note, Chapter 7 describes the refinement of synthesis conditions used to prepare poly-crystalline CPO-27-M (MOF-74) with lower concentrations of base and at low temperature. Refinement of the synthesis of single crystal CPO-27-Mg, -Zn and UTSA-74 was undertaken and the necessary components to forming large single crystals understood

Low temperature synthesis study of metal-organic framework CPO-27 : investigating metal, solvent and base effects down to -78 °C

We thank the EPSRC (EP/K005499/1) (EP/K503162/1) for their financial support of this project and the EPSRC Capital for Great Technologies (EP/L017008/1).CPO-27-M (M = Co, Mg, Ni, Zn) metal-organic frameworks have been successfully synthesized at temperatures down to -78 °C in a range of solvent systems and their crystallinity and morphology analyzed by powder X-ray diffraction and scanning electron microscopy. CPO-27-Mg and -Zn could be synthesized at lower temperatures using MeOH-NaOH as the solvent with CPO-27-Zn showing the most crystalline material at -78 °C. CPO-27-Zn afforded the most crystalline samples of all studies in MeOH-TEA. However, in MeOH a non-porous monomeric [Zn(H2dhtp)(H2O)2] complex was formed when no base was present. In THF with base (NaOH, TEA) the reaction produced crystalline MOFs in a controlled and stable manner at low temperatures, whilst the reagents were insoluble in THF at low temperature when no base was present. SEM was used to analyze the morphologies of the products.PostprintPeer reviewe

Supramolecular architectures with functionalised host ligands

This thesis concerns the rational design and controlled self-assembly of supramolecular architectures for application in areas such as molecular recognition. The research focuses on the cyclotriveratrylene family of molecular hosts, where their incorporation into both polyhedral and polymeric assemblies bestows hosting ability to the complexes isolated. A novel pyridine-N-oxide ligand library has been prepared and the first examples of formal coordination polymers of the lanthanide(III) cations are subsequently reported. Their self assembly was extended to the transition metals and a variety of coordination complexes were isolated that feature uncommon network topologies and structurally aesthetic motifs, such as large internal pore spaces. The combined effects of ligand solubility and rigidity were investigated and used to rationalise the selective isolation of a homochiral, triply-interlocked [2]-catenane over simple capsular assemblies. This was further exemplified in the isolation of a metastable cage complex which underwent a symmetry-induced inter-cage transformation to afford a much larger, polyhedral complex. The solution-phase chemistry of these cages was further investigated and a sophisticated assembly/disassembly cycle was determined. A stable family of cage complexes has been prepared using classical organometallic chemistry and self-assembly processes. Such cages were highly stable and their formation was observed to be cooperative. The solid state host-guest chemistry of these species was investigated, where they were observed to uptake various guests, including gaseous iodine, in a single-crystal-tosingle- crystal manner

Tris-N-alkylpyridinium-functionalised cyclotriguaiacylene hosts as axles in branched [4]pseudorotaxane formation

A series of [4]pseudorotaxanes composed of three-way axle threads based on the cyclotriguaiacylene family of crown-shaped cavitands and three threaded macrocyclic components has been achieved. These exploit the strong affinity for electron-poor alkyl-pyridinium units to reside within the electron-rich cavity of macrocycles, in this case dimethoxypillar[5]arene (DMP). The branched [4]pseudorotaxane= assemblies {(DMP)3∙L}3+,where L = N-alkylated derivatives of the host molecule (±)-tris-(isonicotinoyl)cyclotriguaiacylene, were characterised by NMR spectroscopy and mass spectrometry, and an energy-minimised structure of {(DMP)3∙(tris-(N-propyl-isonicotinoyl)cyclotriguaiacylene)}3+ was calculated. Crystal structures of N-ethyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate and N-propyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate each show ‘hand-shake’ self-inclusion motifs occurring between the individual cavitands

Copper coordination polymers from cavitand ligands: hierarchical spaces from cage and capsule motifs, and other topologies

The cyclotriveratrylene-type ligands (±)-tris(iso-nicotinoyl)cyclotriguaiacylene L1 (±)-tris(4-pyridylmethyl)cyclotriguaiacylene L2 and (±)-tris{4-(4-pyridyl)benzyl}cyclotriguaiacylene L3 all feature 4-pyridyl donor groups and all form coordination polymers with CuI and/or CuII cations that show a remarkable range of framework topologies and structures. Complex [CuI4CuII1.5(L1)3(CN)6]·CN·n(DMF) 1 features a novel 3,4-connected framework of cyano-linked hexagonal metallo-cages. In complexes [Cu3(L2)4(H2O)3]·6(OTf)·n(DMSO) 2 and [Cu2(L3)2Br2(H2O)(DMSO)]·2Br·n(DMSO) 3 capsule-like metallo-cryptophane motifs are formed which linked through their metal vertices into a hexagonal 2D network of (43.123)(42.122) topology or a coordination chain. Complex [Cu2(L1)2(OTf)2(NMP)2(H2O)2]·2(OTf)·2NMP 4 has an interpenetrating 2D 3,4-connected framework of (4.62.8)(62.8)(4.62.82) topology with tubular channels. Complex [Cu(L1)(NCMe)]·BF4·2(CH3CN)·H2O 5 features a 2D network of 63 topology while the CuII analogue [Cu2(L1)2(NMP)(H2O)]·4BF4·12NMP·1.5H2O 6 has an interpenetrating (10,3)-b type structure and complex [Cu2(L2)2Br3(DMSO)]·Br·n(DMSO) 7 has a 2D network of 4.82 topology. Strategies for formation of coordination polymers with hierarchical spaces emerge in this work and complex 2 is shown to absorb fullerene-C60 through soaking the crystals in a toluene solution

Synthesis and crystallographic characterisation of Mg(H2dhtp)(H2O)5·H2O

This work was funded by the British Heart Foundation (NH/11/8/29253) and the EPSRC (EP/K005499/1) (EP/K503162/1). CCDC 1432662 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.A mononuclear complex of composition Mg(H2dhtp)(H2O)5·H2O has been prepared and characterised crystallographically.PostprintPostprintPeer reviewe

Controlling the assembly of cyclotriveratrylene-derived coordination cages

A review of the emerging field of cyclotriveratrylene-derived coordination cages is presented. Ligand-functionalised cyclotriveratrylene (CTV) derivatives self-assemble with a range of metal cations to afford coordination cages, polymers and topologically non-trivial constructs, such as [2]catenanes and a self-entangled cube. Increased control over their self-assembly allows for the controlled and predictable formation of well-defined coordination cages for application in host-guest and recognition chemistry, with surfactant binding and single-crystal-to-single-crystal (SCTSC) uptake of small-molecule guests being observed

The effect of carboxylate position on the structure of a metal organic framework derived from cyclotriveratrylene

Two cyclotriveratrylene-based ligands H3L1 and H3L2 have been synthesised using microwave heating and used in the formation of 1 [Zn2(L1)(DMA)2(CH3COO)] and 2 [Zn6(L2)4(DMA)6(H2O)5] (DMA = N,N-dimethylacetamide). 1 displays an unusual trigonal paddlewheel node geometry, while Zn(II) paddlewheels are observed in 2. However the stacking of CTV molecules in 1 is replaced by an uncommon molecular capsule structure in 2

How does chiral self-sorting take place in the formation of homochiral Pd₆L₈ capsules consisting of cyclotriveratrylene-based chiral tritopic ligands?

The chiral self-sorting process during the self-assembly of homochiral Pd6L8 capsules from cyclotriveratrylene (CTV)-based chiral tritopic ligands (L) and Image ID:c8sc01062e-t1.gif (Py*: 3-chloropyridine) was investigated by an NMR-based approach (QASAP: quantitative analysis of the self-assembly process). From the beginning to the formation of the Image ID:c8sc01062e-t2.gif immature capsules (ICs), enantiomeric ligands are distributed in the intermediates in a non-self-sorting manner, which leads to the isomers of heterochiral ICs over 99% yield. The mismatch of the chirality in the heterochiral ICs prevents intramolecular ligand exchanges in ICs to form the heterochiral capsules. The correction of the chirality in the heterochiral ICs (chiral self-sorting) takes place very slowly to finally lead to the homochiral capsules. The reason why the chiral self-sorting took place in the late stage of the self-assembly (after the formation of the heterochiral ICs) would be due to the relatively high flexibility of the CTV-based ligand

A single crystal study of CPO-27 and UTSA-74 for nitric oxide storage and release

Funding: UK EPSRC EP/K005499/1, EP/K503162, and EP/L017008/1).Single crystal CPO-27-Mg, -Zn and its structural isomer UTSA-74 have been prepared through use of acid modulators; salicylic acid and benzoic acid, respectively. Salicylic acid directed the synthesis of CPO-27-Mg/Zn whereas benzoic acid the synthesis of UTSA-74. Through “in-house” SCXRD, DMF was seen to bind to the Zn2+ and water to the Mg2+ metal sites in CPO-27-M. Although the synthesis conditions were analogous for UTSA-74, DMF is too large to bind due to the proximity of the binding sites. A dissolution–recrystallisation transformation was examined from UTSA-74 to CPO-27-Zn. The release of nitric oxide was measured for each material.PostprintPeer reviewe