Improving the Sustainability of Synthetic Methods for Accessing d- and f-Block Metal–Organic Frameworks

The work described herein explores sustainable methods for the synthesis of metal–organic frameworks (MOFs), a subclass of coordination polymers distinguished from other subclasses by their porosity, which engenders MOFs with high surface area and tunability. This thesis explores various synthetic and post-synthetic methods to obtain a variety of d- and f-block metal MOFs. Chapter 2 explores the use of rotary-evaporation as a distillation technique for the purification and recycling of two solvents commonly used in MOF synthesis and purification, N,N-dimethylformamide and acetone. Solvents previously used for MOF purification are collected, purified, and re-used for MOF synthesis. The quality of the recycled solvents is confirmed by 1H-NMR before being used in the synthesis of four well-studied, structurally diverse d-block metal MOFs, Zr-UiO-66, Zr-MOF-808, ZIF-8(Zn), and HKUST-1(Cu). These MOFs are characterized using a variety of techniques and compared to counterparts synthesized with commercial and as-collected unrecycled solvent in order to confirm viability and efficiency, both in results and environmental impact of the procedure, and to understand the effects of using previously used vs. treated solvents in the synthesis of MOFs. Chapter 3 explores the impact of performing post-synthetic exchange at the metal node (also known as transmetalation) using microwave-assisted heating with the goal of shortening reaction times compared to transmetalation performed using conventional methods. Samples of Y-UiO-66 are transmetalated to yield a library of RE-UiO-66 analogues with seven lanthanoids, Yb(III), Tm(III), Er(III), Ho(III), Tb(III), Gd(III), and Eu(III) using microwave-assisted heating for one and two rounds of transmetalation. The reactions are performed in under three hours compared to weeks with conventional methods. The samples are analyzed for retention of crystallinity and degree of transmetalation to confirm the efficacy of the process and the ability of the MOF to survive microwave conditions