Structural diversity and photo-physical and magnetic properties of dimeric to 1D polymeric coordination polymers of lighter lanthanide(III) dinitrobenzoates

Single crystal diffraction studies reveal the formation of the following 10 new complexes of lighter Ln(III) ions with general formulas {[Ln(μ2-L1)3·(H2O)2]·H2O}n (Ln = Nd (1) and Eu (2)), [Nd(μ2-L2)2·(CH3COO)·(H2O)2]n (3), [Ln2(μ2-L2)5·(L2)·(H2O)4]n (Ln = Sm (4), Ce (5), and Pr (6)), [La2(μ2-L2)6·(H2O)3·(DMF)]n (7) (DMF = dimethylformamide), [Ln(μ2-L2)2·(L2)·(H2O)3]2 (Ln = Eu (8) and Gd (9)) and [Gd(L2)·(CH3COO)2·(H2O)2]2 (10), where L1 and L2 are anions of 3,5- and 2,4-dinitrobenzoic acid, respectively. Complexes 1–7 are 1D coordination polymers, while 8–10 are dinuclear complexes. The luminescence properties of Nd(III) and Eu(III) analogues displayed metal-centred emission with L1 exhibiting weak but more efficient sensitization than L2. A study of the magnetic properties of the compounds clearly demonstrated the field-induced single ion magnet behaviour of the Nd(III) compounds 1 and 3. Their behaviour has been compared to previously reported analogous Nd(III) complexes and the role of the lattice solvent and polymorphism on the magnetic behaviour has been evaluated.