Two Types of Lanthanide Coordination Polymers of (2,3-f)-Pyrazino(1,10)phenanthroline-2,3-dicarboxylic Acid: Syntheses, Structures, and Properties

Hydrothermal reactions of lanthanide oxides with a rigid ligand (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid (H 2 PPDA) yielded 12 novel lanthanide coordination polymers with formulas [Ln(HPPDA)(PPDA)(H 2 O) 2 ]·2H 2 O (Ln = Pr, 1·Pr; Nd, 2·Nd; Sm, 3·Sm; Eu, 4·Eu; Gd, 5·Gd; Tb, 6·Tb; and Dy, 7·Dy ) and [Ln 2 (PPDA) 3 (H 2 O) 4 ]·nH 2 O (Ln = Pr, n = 2, 8·Pr; Ln = Nd, n = 3, 9·Nd; Ln = Sm, n = 2, 10·Sm; Ln = Eu, n = 1, 11·Eu; Ln = Gd, n = 1, 12·Gd ). Single-crystal X-ray diffraction analysis reveals that they present two different structural types. Type I for 1·Pr − 7·Dy possesses a two-dimensional 4·4 network, whereas type II for 8·Pr − 12·Gd exhibits a two-dimensional framework with 3·6 topology. A rationalization for the synthetic pathways that lead to the formation of type I and type II is described. The synthetic reactions gave pure type I as the final product with the emergence of a small amount of type II as an intermediate within the reaction process. Photoluminescence, thermogravimetric, and magnetic analysis of type I were investigated.