Near infrared luminescence of Nd, Er and Yb complexes with perfluorinated 2-mercaptobenzothiazolate and phosphine oxide ligands

Abstract

In order to obtain new NIR luminescent lanthanide complexes free of C-H and C-O bonds the perfluorinated 2-mercaptobenzothiazolate (mbtF) was used as organosulphide antenna ligand and the perfluorinated triphenylphosphine oxide (TPPOF) was used to saturate the coordination sphere of the lanthanide ion. Targeted complexes Ln(mbtF)3(TPPOF)2 (Ln = Nd(1), Er(2) and Yb(3)) were synthesized in high yields from respective silylamides Ln[N(SiMe3)2]3, HmbtF and TPPOF using dry toluene as a solvent. Upon near UV light excitation the compounds 1–3 in the solid state showed an intense NIR photoluminescence which is characteristic for corresponding lanthanide ions. This luminescence was studied at a room temperature by time-resolved methods. The study revealed the presence of intermediate f-f transitions in the time resolved photoluminescence spectrum of 2. The measured lifetimes of Nd and Er NIR emission in 1 and 2 are 39.5 and 53.5 μs respectively. It was found that these lifetimes are among the longest for neat erbium and neodymium complexes with organic ligands.