Crystal Engineering, Syntheses and Structural Evaluations of Coordination Networks

The first part of this thesis (Chapter 3 and Chapter 4), focuses on crystal engineering of multi-metal coordination networks in the aim of developing synthetic strategies to construct porous tandem catalysts. The second part (Chapter 5 and Chapter 6) concerns the synthesis and characterisation of Zn- and Sr-based materials using functionalised biphenyl dicarboxylate linkers. A thorough study of conditions to grow coordination networks from a racemic salen ligand, rac-1,2-cyclohexanediamino-N,N\u27-bis(5-carboxysalicylidene) (H4cdacs), metallated with Cu, VO, Fe and Mn, is reported in Chapter 3. This led to only a small number of successful syntheses. These include a coordination polymer starting from the metallolinker VO(H2cdacs) and a highly open structure, starting from FeCl(H2cdacs), that features heptazinc secondary building unit and unique (cdacs)Fe-O-Fe(cdacs) bridges. The preparation of networks from copper and manganese cdacs complexes were pursued but results that were anticipated based on literature reports were not obtained. The preparation of multi-metal VO(cdacs)-Zn(cdacs) network was attempted but was not successful and similar results to those found here were found in the literature during the course of this work..

Large Pore Isoreticular Strontium-Organic Frameworks: Syntheses, Crystal Structures, and Thermal and Luminescent Properties

Two isoreticular and topologically unique metal-organic frameworks (MOFs) have been synthesized using Sr(NO3)2 and the organic linkers 2-nitro-[1,1′-biphenyl]-4,4′-dicarboxylic acid (H2bpdcNO2) and 2,2′-dinitro-[1,1′-biphenyl]-4,4′-dicarboxylic acid (H2bpdc(NO2)2). The structures of [Sr(bpdcNO2)2(DMF)2(H2O)2] (WUF-15; WUF = Wollongong University Framework) and [Sr4(bpdc(NO2)2)4(DMF)2(H2O)4·2DMF] (WUF-16) were determined by single crystal X-ray diffraction (SCXRD) and are composed of infinite strontium carboxylate SBUs and contain large square (∼18 Å) and smaller triangular channels (∼9 Å) orientated parallel to each other and lined with nitro functional groups. An in situ ligand transformation of H2bpdc(NO2)2 to benzo[c]cinnoline-3,8-dicarboxylic acid (H2bc) and formation of a nonporous coordination polymer of formula [Sr(bc)(H2O)2] (WUF-17) with interesting photoluminescent properties was discovered. Independent synthesis of H2bc enabled the preparation of WUF-17 crystals suitable for SCXRD structure determination. Powder X-ray diffraction and thermal and elemental analyses support the structures of all complexes

A contactless approach for monitoring the mechanical properties of swollen hydrogels

Using a customized ultrasound setup we investigate the feasibility of using a contactless approach to study the bulk mechanical properties of swollen hydrogels. The study involved two different hydrogels, gelatin methacrylate (GelMa) and green algae extract methacrylate (GAEM), which were prepared to provide materials with varying modulus and different swelling properties. Two approaches have been developed. In the first case, ultrasound was compared to Young\u27s modulus measured by indentation. It was found that can be linearly related to indentation modulus values only when the hydrogel swelling ratio is taken into account. In the second approach, an exponential dependency between swelled thickness and indentation modulus was found. This is representative for each hydrogel and purification method in addition to being independent of the conditions used within the toughness range explored. The results of this study indicate that a simple thickness measurement via the proposed approach can provide a direct relationship to Young\u27s modulus upon calibration

Interpenetration isomers in isoreticular amine-tagged zinc MOFs

2019 The Royal Society of Chemistry. The effect of increasing steric size of pendant amine substituents on structural isoreticulation has been studied systematically in a series of Zn-MOFs. Linear biphenyl dicarboxylic acids tagged with pendant primary amine (H2bpdc-NH2), allylamine (H2bpdc-NHallyl), diallylamine (H2bpdc-N(allyl)2) and dimethylamine (H2bpdc-NMe2) groups react with zinc nitrate in DMF to yield a set of interpenetrated MOFs, WUF-11-14, respectively, that are structurally akin to IRMOF-9. The allylated amine ligands undergo C-N cleavage reactions under the synthesis conditions, yielding WUF-12 and WUF-13 as multivariate MOFs. The single crystal X-ray crystallography on this set of MOFs was not straightforward and we give a salutary account of the difficulties encountered. Gas adsorption measurements combined with surface area calculations provide invaluable support for the crystallographic assignments. The crystallographic analyses reveal subtle differences in the relative positions of the interpenetrating frameworks, and we present a classification system for this type of MOF and analyse related examples available in the literature. CO2 adsorption measurements revealed that WUF-14, which features the strongest Brønsted basic dimethylamine tag group, has the highest capacity, isosteric heat of adsorption, and CO2/N2 selectivity

Evaluation of urinary enzymes in newborns treated with gentamicin

Objective(s): In recent years, there has been an increasing amount of study on early diagnosis of kidney injury through sensitive and specific biomarkers. We examined the practical applicability of the urinary levels of NAG (N-acetyl-β-D-glucosaminidase), AP (alkaline phosphatase), and LDH (lactate dehydrogenase) as renal dysfunction screening biomarkers in full and pre-term newborns treated with gentamicin. Materials and Methods: Fourteen pre-term and fifteen full-term newborns who received gentamicin for suspected infections were enrolled. Serum and urine specimens were obtained before the zero days and after gentamicin infusion on the 1st, 3rd, and 5th days of treatment.  Results: In full-term newborns a significant increase in urinary NAG, LDH, AP after 5 days of gentamicin administration compared with control group was noted (

Evaluation of sterilisation methods for bio-ink components: gelatin, gelatin methacryloyl, hyaluronic acid and hyaluronic acid methacryloyl

Reliable and scalable sterilisation of hydrogels is critical to the clinical translation of many biofabrication approaches, such as extrusion-based 3D bioprinting of cell-laden bio-inks. However sterilisation methods can be destructive, and may have detrimental effects on the naturally-derived hydrogels that constitute much of the bio-ink palette. Determining effective sterilisation methods requires detailed analysis of the effects of sterilisation on relevant properties such as viscosity, printability and cytocompatibility. Yet there have been no studies specifically exploring the effects of sterilisation on bio-inks to date. In this work, we explored the effects of various sterilisation techniques on four of the most widely used bio-ink components: gelatin, gelatin methacryloyl, hyaluronic acid, and hyaluronic acid methacrylate. Autoclaving was the most destructive sterilisation method, producing large reductions in viscosity and in mechanical properties following crosslinking. Filter sterilisation caused some reduction in rheological properties of GelMA due to removal of higher molecular weight components, but did not affect photocrosslinking. Ethylene oxide (EtO) was the least destructive sterilisation method in terms of rheological properties for all materials, had no detrimental effect on the photocrosslinkable methacrylate/methacrylamide groups, and so was chosen for more detailed examination. In biological analyses, we found that EtO treatment successfully eradicated a bacterial challenge of E. coli, caused no decrease in viability of human mesenchyman stem cells (hMSCs), and had no effect on their rate of proliferation. Finally, we found that EtO-treated hydrogels supported encapsulated hMSCs to differentiate towards the chondrogenic lineage, and to produce new cartilage matrix. Our results bring to light various effects that sterilisation can have on bio-inks, as well as highlighting EtO sterilisation as a method which minimises degradation of properties, while still promoting biological function