Synthesis and characterisation of novel metal organic frameworks for biomedical and environmental applications
Winterlich, Meghan
Winterlich, Meghan
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Publication Date
2021-09-09
Type
Thesis
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Abstract
Metal organic frameworks (MOFs) have received significant attention in recent years in the areas of biomedical and environmental applications. Among them, mixed metal MOFs and highly porous MOFs, although promising, are relatively few in numbers. Therefore, the ultimate goal achieved in this dissertation is to 1) synthesize novel highly porous and/or mixed metal MOFs, and 2) investigate their ability to encapsulate guest molecules focusing on drugs for biomedical applications or dyes and metals for environmental applications. Chapter 1 provides a detailed literature review introducing MOFs, their properties and their use in both biomedical and environmental applications. The first goal this thesis is concerned with, is the synthesis and structural characterization of mixed metal MOFs. Chapter 2 introduces the NUIG Family of MOFs where is presented NUIG1, a biocompatible ZnNa2 MOF based on the organic linker benzophenone 4,4 dicarboxylic acid. NUIG1 displays a novel topology and is a rare example of a mixed metal MOF based on 1D rod secondary building units. Due to its biocompatibility, determined using MCF-7 cells and an MTT assay, it was investigated as a drug carrier for biomedical applications. UV-vis, HPLC, TGA, XRPD, solid state NMR and computational studies indicated that NUIG1 exhibits a record amount of Ibuprofen (Ibu) encapsulation and high nitric oxide adsorption capacity. NUIG1 can also be used in environmental applications where it exhibits good performance in the adsorption of metal ions (CoII, NiII, CuII) from aqueous environments, as was demonstrated by UV-vis, EDX, ICP, SEM. Direct and alternate current magnetic susceptibility studies revealed that the magnetic properties of NUIG1 depend on the amount and type of the encapsulated metal ion. This work has been published in Material Advances, 2020,1, 2248-2260. The employment of benzophenone-4,4’-dicarboxylic acid (bphdcH2) in MOF chemistry was further investigated in Chapter 3, providing access to the 3D mixed metal MOFs NUIG2 and NUIG3, and the 2D homometallic MOF 1•DMF. NUIG2 and NUIG3 are structural analogues of NUIG1. Both NUIG2 and NUIG3 display high metal ion (CoII, NiII, CuII) adsorption capacity, comparable to that of NUIG1. Monte Carlo simulations were conducted in NUIG1 in order to assess its adsorption capacity for other guest molecules and revealed that it possesses an outstanding CO2 uptake at ambient pressure, which is larger than that of the previously reported best functioning species (104 vs 100 cm3 (stp)/cm3). This work has been published in Dalton Transactions, 2021, 50, 6997-7006. Chapters 4 and 5 focus on the synthesis of highly porous MOFs and their ability to encapsulate larger organic molecules. Specifically, the ability of these materials to encapsulate and release the anticancer drug Doxorubicin (Dox) and/or other environmentally hazardous species, such as dyes, was thoroughly investigated. The employment of multitopic elongated linkers in MOF chemistry provided access to highly porous 3D MOFs, NUIG5, NUIG6 and NUIG7. These MOFs are all structural analogues which were synthesized by slightly modifying the synthetic process; in particular, the replacement of Zn(CH3CO2)2·2H2O (used for NUIG5) with Co(CH3CO2)2·2H2O provided access to NUIG6 and the replacement of L1 (used for NUIG5) with L2 provided access to NUIG7. Chapter 4 covers the synthesis, characterization, and properties of NUIG5 and NUIG6. N2 adsorption measurements revealed that these MOFs are highly porous with a surface area of 4841 m2/g. It is noteworthy to mention, there are very limited number of MOFs with a surface area of around 5000 m2 g-1. NUIG5 showed a high encapsulation for the large anti-cancer drug -Dox (1100mg Dox/g NUIG5). The HDF cell line was used to assess the toxicity of NUIG5 and its organic linker, they are not toxic and can be used as potential drug carriers. The cytotoxic effect of Dox@NUIG5 was also investigated, revealing similar LC50 values to that of unloaded NUIG5 and less toxicity towards healthy cells in comparison to free Dox. NUIG5 showed to also encapsulate large amounts of Rhodamine B (RhB) and Brilliant green (BG) dyes determined by UV Vis studies. NUIG7 and its Dox encapsulation is presented in Chapter 5. UV-vis, FTIR and TGA, studies indicated that NUIG7 also exhibits an exceptionally high Dox adsorption capacity (1850 mg Dox/g NUIG7), larger than that of NUIG5. Cytotoxicity studies revealed an LC50 value of 70µM. Finally, Chapter 6 discusses the synthesis and characterization of other members of the NUIG family of MOFs, using novel, polytopic, Schiff based carboxylate linkers (L1-L5). The employment of multitopic elongated linkers in MOF chemistry provided access to series of highly porous 3D MOFs. Due to their highly porous nature, they can potentially be used to encapsulate large organic molecules link Doxorubicin (Dox) or organic dyes. Cytotoxicity studies of these ligands and MOFs revealed that they are non-toxic at concentrations typical needed for the administered dosage anticancer drugs like of Dox and as a result can be potentially used in biomedical applications.
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NUI Galway