Spectroscopy and Structure of LnIII Complexes with Sulfonylamidophosphate‐Type Ligands as Sensitizers of Visible and Near‐Infrared Luminescence

Abstract

AbstractLanthanide complexes with sulfonylamidophosphate‐type ligands: dibenzyl(phenylsulfonyl)amidophosphate (HSB) and di(4‐methylphenyl)‐phenylsulfonyl‐amidophosphate (HSK) have been synthesized and show promise as new sensitizers of visible and near‐infrared luminescence. They constitute a new part of coordination chemistry for this type of ligand, creating simultaneously a new class of lanthanide complexes with π‐conjugated ligands possessing the structural fragment SO2NHP(O). Two series of stable lanthanide complexes Na[Ln(SB)4] (1Ln) and Na[Ln(SK)4] (2Ln), where Ln=NdIII, EuIII, GdIII, TbIII, ErIII, YbIII, were characterized by X‐ray structure analysis. The IR, absorption, emission, and excitation spectra at 293, 77, and 4 K, as well as luminescence decay times and emission quantum yields were used to characterize the complexes in the solid state. The relation between the crystal structure and its spectroscopic properties is also discussed. The influence of the π–π stacking interactions and a ligand‐to‐metal charge transfer state on ligand‐to‐metal energy transfer efficiency was demonstrated and discussed. Crystal‐field lines determined from absorption and fluorescence spectra of 2Nd were used in computational analysis employing free‐ion operators, one‐electron crystal‐field operators, and two‐particle correlation crystal‐field operators. The performed analysis enabled the determination of the Hamiltonian parameters and an unambiguous assignment of 85 crystal‐field levels of NdIII ion with a mean error of 12.0 cm−1.