Effect of lanthanide contraction on crystal structures of three-dimensional lanthanide based metal-organic frameworks with thiophene-2,5-dicarboxylate and oxalate

摘要

Six three-dimensional (3D) lanthanide coordination polymers with formula [Ln(TDC)(ox)_(0.5)(H_2O)_2]?(H_2O) (1Ln) (Ln = Pr 1, Nd 2, Sm 3, Gd 4) and [Ln(TDC)(ox)_(0.5)(H _2O)_2]?(H_2O) (2Ln) (Ln = Dy 5, Er 6) 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 1Ln and 2Ln are isomers that may be produced by lanthanide contraction. Compounds 1-4 are isostructural and possess binodal (4,5)-connected 3D framework of tcj/hc topology with triangular channels along the [101] direction. Isostructural compounds 5 and 6 present trinodal (4,4,6)-connected 3D framework of sqc254 topology with rectangular channels along the b axis. The magnetic properties reveal that compound 2 has antiferromagnetic behavior, while compound 4 has ferromagnetic behavior. The luminescent property shows that compound 5 displays intense yellow luminescence and exhibits the typical Dy ~(3+) 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.