Abstract
Dynamic covalent chemistry is a powerful tool to synthesise complex structures from simple building blocks. However, even minor variations in the numerous parameters governing self-assembly can drastically influence the size and structure of the resulting assemblies. Herein, we report the selective formation of three cages belonging to the low-symmetry Tri(2) (2)Tri(2) cage topology for the first time, using highly symmetric tritopic building blocks, confirmed by single-crystal X-ray (SC-XRD) analysis. Fluorinated and non-fluorinated aldehydes were combined with two amines differing in their degree of structural flexibility. Applying either kinetic or thermodynamic control through solvent selection allowed for the selective synthesis of either the low-symmetry Tri(2) (2)Tri(2) or the larger, highly symmetric Tri(4)Tri(4) assemblies. While the fluorinated linker strongly preferred the formation of the Tri(2) (2)Tri(2) cage topology under thermodynamic control, the non-fluorinated linker selectively formed the Tri(4)Tri(4) species. Kinetic control, using methanol as a poor solvent, allowed for the selective precipitation of the Tri(2) (2)Tri(2) intermediate. Reduction of the Janus-like fluorinated Tri(2) (2)Tri(2) cages yielded the cages Et(2)F(2) (red) and TREN(2)F(2) (red), which showed high potential for removing perfluorooctanoic acid (PFOA) from water, with Et(2)F(2) (red) exhibiting structural rearrangements in organic solvents to accommodate PFOA, as observed by (1)H and (19)F NMR titrations in combination with (19)F DOSY measurements.