The influence of different cations on the structure and spectral properties of Ln 3+ tetrakis-complexes with the CAPh-type ligand dimethyl- N -trichloroacetylamidophosphate

Lanthanide coordination compounds NMe 4 [LnL 4 ], NEt 4 [LnL 4 ] and PPh 4 [LnL 4 ] (Ln 3+ = Eu, Gd, Tb) with the carbacylamidophosphate (CAPh) ligand dimethyl- N -trichloroacetylamidophosphate (HL= Cl 3 CC(O)N(H)P(O)(OMe) 2 ) were synthesized. These complexes are characterized using infrared, ultraviolet diffuse reflection, and luminescence spectroscopy as well as through elemental and X-ray analyses. The effect of changing the cation type on the structure and luminescence properties of the tetrakis-complex [LnL 4 ] − was analyzed. TD-DFT calculations reveal cation-specific contributions to the excited states in tetrakis complexes, with [PPh 4 ] + playing a central role in both singlet and triplet states. This leads to longer donor–acceptor distances compared to NMe 4 [LnL 4 ] and NEt 4 [LnL 4 ]. Additionally, intramolecular energy transfer (IET) calculations for Eu 3+ and Tb 3+ tetrakis compounds reveal Tb 3+ sensitization via S 1 and Eu 3+ via the typical T 1 state.