Luminescent complexes of Eu3+,Tb3+ and Gd3+ nitrates with polytopic ligand 2,4,6-tris(1H-pyrazol-1-yl)-1,3,5-triazine

Three novel coordination compounds based on 2,4,6-tris(1H-pyrazolyl)-l,3,5-triazine ligand (PzTz), namely [Ln(PzTz)(NO3)3(H2O)] (Ln = Eu, Gd, Tb) were synthesized and spectroscopically and structurally characterized. X-ray diffraction experiments revealed the monomeric nature of the complexes exhibiting either "sphenocorona" or bicapped square antiprism distorted coordination geometry, the lanthanide ions being ten-coordinated. The relatively high energy of triplet state of the ligand (T1 = 23000 cm-1) has been demonstrated to be favorable for sensitization of Tb3+ ion and this has been proved by luminescence decay measurements as well as by experimental determination of photoluminescence quantum yield (? = 34 %)