Syntheses and characterizations of two-dimensional lanthanide coordination polymers based on anthraquinone-1,4,5,8-tetracarboxylic acid

A series of isostructural two-dimensional lanthanide complexes with the formula [Ln(Haqtc)(H2O)4·xH2O]n (Ln = Nd, 1; Sm, 2; Eu, 3; Tb, 4; Dy, 5; Er, 6.) were synthesized by treating H4aqtc (H4aqtc = anthraquinone-1,4,5,8-tetracarboxylic acid) with lanthanide(III) salts under hydrothermal conditions. 3-D structures are formed by inter-layer hydrogen bonds. Magnetic susceptibility measurements of complexes 4 and 5 in temperature range 2–300 K were performed, which showed dominant weak ferromagnetic interactions in 4 and slow magnetization relaxation in 5.