Structural and spectroscopic investigations of europium(III) entrapped by the ethylenediaminetetra(methylenephosphonate) ligand in K12H8[Eu4(EDTMP)4] · 45H2O crystal

The X-ray crystal structure of an anionic octacoordinate Eu3+ complex of the formula K12H8[Eu4(EDTMP)4] · 45H2O, where EDTMP is the ethylenediaminetetra(methylenephosphonate) anion, hereinafter referred to as I, has been determined. The crystal consists of cyclic tetrameric complex anions, in which the surrounding of each Eu3+ ion is composed of two nitrogen atoms and six oxygen atoms from phosphonate groups. One of the phosphonate groups in the ligand molecule is tridentate (O:O′,O″), thus giving rise to the formation of the tetramers. The compound was characterized by UV–Vis electronic spectroscopy. At room and liquid nitrogen temperatures the complex shows luminescence from both 5D0 and 5D1 states, the latter one, which is very rare in Eu3+ compounds with organic ligands, is probably brought about by the saturation of the coordination sphere with the phosphonate groups.

Graphical abstractThe structure and spectroscopy of the crystal of an anionic octacoordinate Eu3+ complex with a ethylenediaminetetra(methylenephosphonate) ligand, K12H8[Eu4(EDTMP)4] · 45H2O, is described; the crystal luminesces from both 5D0 and 5D1 states.Figure optionsDownload full-size imageDownload as PowerPoint slide