Towards the synthesis of novel chelates for technetium-99m imaging

Abstract This thesis details the synthesis of tetradentate ligand systems for use with technetium-99m with a focus on sulphur donors. The synthesis of a series of S4 tetradentate ligands is detailed (Chapter 3). The ligands with general formula Me2PS(CH2)2S(CH2)nS(CH2)2PSMe2 where n = 2 – 4 (3.1 – 3.3). The ligands were reacted with technetium-99m, [ReO2(py)4]Cl and [ReOCl3(PPh3)2] unfortunately evidence for complexation was not obtained. In order to gain an understanding of the coordination chemistry of the ligands 3.1 – 3.3 were successfully complexed to Cu(I), Ag(I) and Pd(II) centres, the compounds and structures are discussed in chapter 3. The synthesis of ligands containing 1-methyl-2H-imidazole-2-thione units, which act as S donors is featured in chapter 4. Challenges met during the synthesis of the S4 and N2S2 ligands are discussed. P2S2 (4.12 and 4.16) ligands were synthesised by the reaction of the imidazole unit with 1,3-propanebis(phenyldihydroxymethylphosphine) dichloride. This led to the subsequent synthesis of an analogous P2O2 (4.17) ligand using 1-ethyl-2H-imidazolin-2-one. The P2S2 and P2O2 chelates were reacted with PdCl2 to produce Palladium(II) complexes. Reactions with [ReOCl3(PPh3)2] were also completed and although pure samples were not isolated, there is evidence that [ReO2L]+ complexes were synthesised. The synthesis of a tetradentate phosphine oxime (P2N2) ligand system is the focus of chapter 5. The synthetic challenges encountered during the proposed synthesis are detailed along with alternative synthetic routes. The synthesis of analogous P2N2 compounds is also reported. Whilst evidence for the target chelate (5.2) was obtained its synthesis could not be fully confirmed.Open Acces

Improvements to the production of ZIF-94; a case study in MOF scale-up

The authors acknowledge the financial support of the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013), under grant agreement no. 608490, M4CO2 project.The ability to produce large scale quantities of MOF materials is essential for the commercialisation of these frameworks to continue. Herein we report how the production of ZIF-94 can be improved from a ∼1 g laboratory preparation to a scalable procedure allowing for large scale production of the desired framework. The synthesis of ZIF-94 was completed at room temperature, atmospheric pressure and without the use of DMF as a solvent. This method offers improvements over the current literature synthesis routes and affords a product at 18 wt% solids. To demonstrate the robustness of the derived methodology a 60 g, large scale, batch of this framework was produced which possessed a surface area of 468 m2 g−1. This large scale sample has superior CO2 uptake of 3.3 mmol g−1 at 1 bar, an improvement of 30% over literature reports.Publisher PDFPeer reviewe

Ammonia mobility in chabazite: insight into the diffusion component of the NH ₃-SCR process

To assess the effect of counterion presence on NH3 mobility in commercial automotive emission control zeolite catalysts, NH3 mobility in NH3-SCR catalyst Cu-CHA was compared with H-CHA using quasielastic neutron scattering and molecular dynamics simulations.</p

Structural Descriptors of Zeolitic–Imidazolate Frameworks Are Keys to the Activity of Fe–N–C Catalysts

International audienceActive and inexpensive catalysts for oxygen reduction are crucially needed for the widespread development of polymer electrolyte fuelcells and metal−air batteries. While iron−nitrogen−carbon materials pyrolytically prepared from ZIF-8, a specific zeolitic imidazolate framework(ZIF) with sodalite topology, have shown enhanced activities toward oxygen reduction in acidic electrolyte, the rational design of sacrificialmetal−organic frameworks toward this application has hitherto remained elusive. Here, we report for the first time that the oxygen reduction activity of Fe−N−C catalysts positively correlates with the cavity size and mass specific pore volume in pristine ZIFs. The high activity of Fe−N−C materials prepared from ZIF-8 could be rationalized, and another ZIF structure leading to even higher activity was identified. In contrast, the ORR activity is mostly unaffected by the ligand chemistry in pristine ZIFs. These structure−property relationships will help identifying novel sacrificial ZIF or porous metal−organic frameworks leading to even more active Fe−N−C catalysts. The findings are of great interest for a broader application of the class of inexpensive metal−nitrogen−carbon catalysts that have shown promising activity also for the hydrogen evolution (Co−N−C) and carbon dioxide reduction (Fe−N−C and Mn−N−C)