Effect of Lanthanide Contraction on Crystal Structures of Three-Dimensional Lanthanide Based Metal–Organic Frameworks with Thiophene-2,5-Dicarboxylate and Oxalate

Abstract

Six three-dimensional (3D) lanthanide coordination polymers with formula [Ln(TDC)(ox)_0.5(H₂O)₂]·(H₂O) (<b>1Ln</b>) (Ln = Pr <b>1</b>, Nd <b>2</b>, Sm <b>3</b>, Gd <b>4</b>) and [Ln(TDC)(ox)_0.5(H₂O)₂]·(H₂O) (<b>2Ln</b>) (Ln = Dy <b>5</b>, Er <b>6</b>) have been synthesized by hydrothermal reactions of thiophene-2,5-dicarboxylate (TDC) and oxalate (ox) with corresponding lanthanide nitrate. X-ray crystal structure analyses reveal that <b>1Ln</b> and <b>2Ln</b> are isomers that may be produced by lanthanide contraction. Compounds <b>1</b>–<b>4</b> are isostructural and possess binodal (4,5)-connected 3D framework of tcj/hc topology with triangular channels along the [101] direction. Isostructural compounds <b>5</b> and <b>6</b> present trinodal (4,4,6)-connected 3D framework of sqc254 topology with rectangular channels along the <i>b</i> axis. The magnetic properties reveal that compound <b>2</b> has antiferromagnetic behavior, while compound <b>4</b> has ferromagnetic behavior. The luminescent property shows that compound <b>5</b> displays intense yellow luminescence and exhibits the typical Dy³⁺ ion emission. Furthermore, infrared (IR), thermogravimetric analyses (TGA), elemental analyses (EA), powder X-ray diffraction (PXRD), magnetic and luminescent properties of these compounds are also investigated.