Carboxylic acid-dependent assembly of neodymium-organic frameworks with attractive topologies and second-order nonlinear optical and/or magnetic properties

Four new neodymium(III) coordination polymers, Nd(HL)(2)(CH3COO) (1), Nd(HL)(2)(CH3COO) (1'), Nd(HL)(2)(C2H5COO) (2) and Nd(HL)(3)(H2O) center dot 4H(2)O (3) were prepared by the hydrothermal reactions of Nd2O3 with 1,6-dihydro-6-oxopyridine-3-carboxylic acid (H2L) using the modulation roles of different carboxylic acids (acetic acid, malonic acid, propionic acid and formic acid for 1, 10, 2 and 3, respectively). Complexes 1 and 1' are conformational polymorphs : 1 crystallizes in an acentric space group Cmc2(1) and shows a new 3D {3,6} topology (6 3) 2(4 2 6 10 8 3), while 10 crystallizes in the centrosymmetric space group Pbcn, exhibiting the rutile topology. Complex 2 possesses the same space group and topology as 1'. Complex 3 exhibits a new 2D three-node network topology with the Schlafli symbol of (8 3). Complex 1 is a second-order nonlinear optical molecular material, and magnet measurements indicated the magnetic coupling interaction between Nd3+ ions in these four complexes is weak.