Two isomorphous 3-D lanthanide oxalatophosphonate frameworks based on glyphosate: Syntheses, crystal structures, and luminescence properties

Two new 3-D isomorphous lanthanide(iii) compounds [Eu(H L)(CO)]·2. 51HO (1) and [Tb(HL)(C O)]·2.46HO (2, H L = glyphosate), based on glyphosate and oxalate have been successfully synthesized under hydrothermal conditions, and structurally characterized. In the two compounds, tetra-connected glyphosate ligands are coordinated to Ln, resulting in the formation of 1-D {Ln (HL)} double chains along the c direction. Each of the chains is connected to its four neighbors via the O atoms of phosphates of HL ligands, resulting in a 3-D (4, 6)-connected framework with 4·5·6 ·7 topology, which possesses 1-D channels with oxalates and lattice water molecules as troglodytes. The oxalates are stabilized via chelating Ln in the form of 1-D Ln-CO zigzag chains along the c direction. To the best of our knowledge, compounds 1 and 2 represent the first single-crystal structures of lanthanide(iii)-glyphosate compounds incorporating second ligands. The luminescent properties of compounds 1 and 2 have been investigated at room temperature. The energy gaps between the triplet excited state of oxalic acid and the lowest excited resonance levels of Eu (D ) and Tb (D) are 7270 cm and 4070 cm, respectively, indicating that oxalate is more suitable for the sensitization of Tb luminescence than Eu luminescence. © 2011 The Royal Society of Chemistry.