Taking the third route for construction of POMOFs: the first use of carboxylate-functionalized MnIII-Anderson-Evans POM-hybrid linkers and lanthanide nodes

The purpose of the present contribution is to illustrate how to design and grow crystals of POMOFs based on POM hybrid linkers with lanthanide ions as nodes. Thus the MnIII centered Anderson-Evans polyoxometalate (Mn-A-E-POM) was functionalized with 4-(((1,3-dihydroxy-2-(hydroxymethyl)propan-2 yl)amino)methyl)benzoic acid (LH3) to afford the hybrid inorganic-organic POM [N(n C4H9)4]4[(MnMo6O18)((OCH2)3CNHCH2(C6H4)COOH)((OCH2)3CNHCH2 (C6H4)COO)] (1), which in turn reacts with lanthanide salts and yields two three-dimensional frameworks with the general formulae Ln(DMF)6Ln(DMF)5Ln3(DMF)10[(MnMo6O18) ((OCH2)3CNHCH2(C6H4)COO)2]3·xDMF (Ln = La - Nd) (2) and [Ln(DMF)4(H2O)]2 [Ln3(DMF)6][(MnMo6O18)((OCH2)3CNHCH2(C6H4)COO)2]3·xDMF (Ln = Y, Sm - Lu) (3). The differentiation in these two families results from the lanthanide contraction. The crystallization process is crucial for obtaining these two families in bulk pure phase. Family (2) can be obtained by stirring, while for family (3) the less energy demanding layering method proved to be the most efficient pathway. Notably, the change in the ionic radii causes a change in space group (from P21 (family (2)) to P21/c (family (3)), however, the topology of the frameworks is unaffected.