A library of three dinuclear complexes [Yb(hfac)3(L)]2⋅3(CH2Cl2) (1)⋅3(CH2Cl2), [Dy2(hfac)6(L)3]⋅3(CHCl3) (4)⋅3(CHCl3), [Yb(tta)3(L)]2 (6), four dinuclear enantiomers [Ln(facam)3(L)]2⋅CH2Cl2 Ln=Dy ((-)7⋅CH2Cl2, (+)7⋅CH2Cl2) and Yb ((-)8⋅CH2Cl2, (+)8⋅CH2Cl2), two tetranuclear complexes [Ln2(hfac)6(L)]2⋅(CH2Cl2)n (Ln = Yb, n =1 (2)⋅CH2Cl2
Ln = Dy, n = 0 (3)) and two pentanuclear complexes [Dy5(hfac)15(L)3]⋅2(C2H4Cl2) (5)⋅2(C2H4Cl2) and [Nd5(hfac)15(L)3]⋅2(CH2Cl2) (10)⋅2(CH2Cl2) (1,1,1,5,5,5-hexafluoroacetylacetonate (hfac-), 2-tenoyltrifluoroacetylacetonate (tta-), 3-(trifluoro-acetyl-(+/-)-camphorate (facam-) and L = [4'-(4'''-pyridyl-N-oxide)-1,2':6'1''-bis-(pyrazolyl)pyridine] ligand) were isolated and characterized by single crystal X-ray diffraction. The final molecular architectures could be controlled by playing with the ionic radii of Yb(III), Dy(III) and Nd(III) ions and steric hindrance of the β-diketonate. Natural circular dichroism (NCD) highlighted no exciton CD couplet for chiral compounds. All the compounds involving Nd(III) in both O9 and N3O6, Dy(III) in O9 and Yb(III) in both O8 and N3O6 coordination sphere present field-induced SMM while Dy(III) in O8 environment displays SMM behavior in zero applied dc field. The relaxation of the magnetization occurs mainly through a Raman process with contribution of QTM in zero field and Direct process under applied field. The relaxation time of the magnetization increases with the enhancement of the steric hindrance of the ancillary β-diketonate ligands.