“…Because lanthanide ions can be considered as hard acids according to Pearson’s theory [ 37 ], the choice of the ligand is of first importance as far as polynuclear hydroxidolanthanide based cluster metal-organic frameworks is concerned. Most of them are built with the classical benzoic multicarboxylate ligands, such as terephthalate [ 16 , 38 , 39 ], 2-hydroxyterephthalic [ 18 ], 2,5-dihydroxyterephthalic, 1,2,3- or 1,3,5-benzenetricarboxylic, 1,2,4,5-benzenetetracarboxylic and 4,4′-biphenyldicarboxylate acid, which are versatile building blocks to obtain various high dimensional lanthanide frameworks due to their variety of bridging abilities [ 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ].…”