Post-Synthetic Shaping of Porosity and Crystal Structure of Ln-Bipy-MOFs by Thermal Treatment

The reaction of anhydrous lanthanide chlorides together with 4,4′-bipyridine yields the MOFs [Formula: see text] [Ln(2)Cl(6)(bipy)(3)]·2bipy, with Ln = Pr − Yb, bipy = 4,4′-bipyridine, and [Formula: see text] [La(2)Cl(6)(bipy)(5)]·4bipy. Post-synthetic thermal treatment in combination with different vacuum conditions was successfully used to shape the porosity of the MOFs. In addition to the MOFs microporosity, a tuneable mesoporosity can be implemented depending on the treatment conditions as a surface morphological modification. Furthermore, thermal treatment without vacuum results in several identifiable crystalline high-temperature phases. Instead of collapse of the frameworks upon heating, further aggregation under release of bipy is observed. [Formula: see text] [LaCl(3)(bipy)] and [Formula: see text] [Ln(3)Cl(9)(bipy)(3)], with Ln = La, Pr, Sm, and [Formula: see text] [Ho(2)Cl(6)(bipy)(2)] were identified and characterized, which can also exhibit luminescence. Besides being released upon heating, the linker 4,4′-bipyridine can undergo activation of C-C bonding in ortho-position leading to the in-situ formation of 4,4′:2′,2′′:4′′,4′′′-quaterpyridine (qtpy). qtpy can thereby function as linker itself, as shown for the formation of the network [Formula: see text] [Gd(2)Cl(6)(qtpy)(2)(bipy)(2)]·bipy. Altogether, the manuscript elaborates the influence of thermal treatment beyond the usual activation procedures reported for MOFs.