Synthesis and coordination chemistry of boron-functionalized poly(pyrazolylpyridyl)borate with Ln(III) metals

A new family of lanthanide/boron-based complexes have been synthesized from the novel substituted poly(pyrazolylpyridyl)borate ligand containing phenyl substituents on the boron atom Ph2Bp^py (L). The complexes have been fully characterized by analytical and spectroscopic methods. The single crystal X-ray structure and mass spectroscopy reveal the isostructural dinuclear complexes: [Ln2(L)2(NO3)2(OH)2] where Ln = Eu, Gd or Tb. Upon excitation of the Ln(III) complexes in DCM, their luminescence spectra display narrow f–f transitions. It is found that the ligand can efficiently sensitize the Tb(III) complex because of the better triplet state energy match to the Tb(III)–^5D0 excited states.