Synthesis, Crystal Structures, and Photophysical Properties of Lanthanide Complexes Containing Pyrrole‐Derivatized Carboxylate Ligands

Two pyrrole‐deriviatized carboxylic acids [ L 1 = 1‐methylpyrrole‐2‐carboxylate] and [ L 2 = N ‐methyl‐3‐indoleglyoxylate] were used as ligands to prepare six lanthanide coordination compounds [( L 1 ) 3 Ln] n (Ln = Eu, 1 ; Gd, 2 ; Tb, 3 ) and [( L 2 ) n Ln(NO 3 )(MeOH) 2 ] n (Ln = Eu, 4 ; Gd, 5 ; Tb, 6 ). These complexes have been synthesized and structurally characterized by single‐crystal X‐ray diffraction. The phosphorescence behavior of the ligands in the Gd 3+ complexes show that modification of the ligands can tune the triplet energy levels of the ligands so that they match the 5 D 0 energy level of Eu 3+ and the 5 D 4 energy level of Tb 3+ ; thus, the energy transfer efficiency from antenna to Eu 3+ and Tb 3+ is improved, and the Eu 3+ and Tb 3+ emission intensity is enhanced. This concept can be applied towards improving the luminescent properties of Ln 3+ complexes by the modification of coordinating ligands. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)