Luminescence enhancement by mixing carboxylate benzoate-pentafluorobenzoate ligands in polynuclear {EuZn} and {TbZn} complexes.

This study investigates mixed-carboxylate benzoate (bz)-pentafluorobenzoate (pfb) {EuZn} and {TbZn} compounds with 1,10-phenanthroline (phen) molecules. It is demonstrated that variation of the synthesis conditions yields mixed-carboxylate compounds with different compositions: [LnZn(phen)(bz)(pfb)] (Ln = Eu (1Eu), Tb (1Tb)) and [EuZn(phen)(bz)(pfb)]·4MeCN (2Eu). In these structures, bz and pfb anions occupy specific positions in various ratios. Benzoate compounds [LnZn(phen)(bz)] (Ln = Eu (3Eu), Tb (3Tb)) were synthesized in order to compare the structures and photoluminescence properties of complexes 1 and 2 with their homoanionic analogues, and comparison was also made with previously reported pentafluorobenzoate complexes [LnZn(pfb)(phen)] (Ln = Eu (4Eu), Tb (4Tb)). It was found that the introduction of a second type of anion into the studied compounds improves the photoluminescence properties and alters the geometry of the metal core, the polyhedra of rare-earth elements (REEs), and the system of non-covalent interactions compared to benzoate and pentafluorobenzoate complexes.