This work explores a particular sub-field of metal–organic frameworks (MOFs) incorporating rare-earth (RE) metals, also called RE-MOFs, that have been gaining traction over the last 30 years. The specific family studied here, analogues of the archetypical UiO-66, incorporates RE(III)-hexanuclear clusters and linear organic linkers, giving rise to a network with fcu topology named RE-UiO-66. Herein, the following is presented (i) the design, synthesis, and characterisation of the RE-UiO-66 (RE = Y(III), Eu(III), Gd(III), Tb(III), Ho(III), Er(III), Tm(III), and Yb(III)); (ii) the challenges and optimised approaches for the synthesis of each RE-UiO-66 analogue; (iii) the crystalline structure of the entire family of RE-UiO-66 analogues, through the use of single crystal X-ray diffraction (SCXRD); and (iv) the challenges associated with synthesising early lanthanoid analogues of RE-UiO-66 (RE = La(III), Ce(III), Pr(III), and Nd(III)).
Chapter 2 delves into the synthetic optimisation, and characterisation of a series of RE(III) analogues of Zr(IV)-UiO-66. RE-UiO-66 shows several similarities to Zr-UiO-66, a well-studied MOF in the literature; but the post-activation stability of the former is not similar to the latter one, requiring further optimisation. The physical and chemical properties of RE-UiO-66 and some stabilisation pathways, as well as the crystal structure of Tm-UiO-66, are discussed further.
Chapter 3 aims to explain trends in bond lengths observed in the crystal structures of RE-UiO-66 (RE = Y(III), Eu(III), Gd(III), Tb(III), Ho(III), Er(III), Tm(III), and Yb(III)). These trends are then used to explain some of the physical and chemical properties of the RE-UiO-66 series as described in Chapter 2. By using acidic conditions and high temperatures, single crystals suitable for SCXRD are obtained. From this data, the structure of each RE-UiO-66 analogue was solved and refined.