Structural and Luminescent Features of Lanthanide Ate Complexes with Polychlorinated 2-Mercaptobenzothiazolate Ligands

Abstract

Partially and fully chlorinated 2-mercaptobenzothiazoles, namely 5,6-dichloro-1,3-benzothiazol-2(3H)-thione (Hmbt Cl2 ) and 4,5,6,7-tetrachloro-1,3-benzothiazol-2(3H)-thione (Hmbt Cl4 ), were utilized as sensitizers for lanthanide luminescence. Lanthanide ate complexes 1−6, having the general formula [Na(DME) 3 ] + [Ln(mbt Cln ) 4 ] − (1: Ln = Nd, n = 2; 2: Ln = Gd, n = 2; 3: Ln = Tb, n = 2; 4: Ln = Nd, n = 4; 5: Ln = Gd, n = 4; and 6: Ln = Tb, n = 4), were synthesized using a convenient one-pot route, which included the interaction of the respective thiones with lanthanide and sodium silylamides. X-ray studies of complexes 1, 3, 4, and 6 revealed the difference in the coordinating fashion of the ionic lanthanide complexes with the mbt Cl2 and mbt Cl4 ligands. Furthermore, the electron density topologies for complexes 1, 3, 4, and 6 were investigated. The triplet levels of the mbt Cl2 and mbt Cl4 ligands, which were obtained from the phosphorescence spectra of the Gd complexes 2 and 5, lie at 21 800 and 19 400 cm −1 respectively. In complexes 1, 3, and 4, mbt Cl2 and mbt Cl4 act as antenna ligands, sensitizing the visible f−f photoluminescence of Tb 3+ and the near-infrared photoluminescence of Nd 3+ . In the case of the Nd complex 4, the intensity of the metal-centered luminescence is enhanced because of the optimal triplet level energy of mbt Cl4 , the efficient shielding from C−H quenchers, and the low symmetry of the ion environment.

Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction

“…This experimental–theoretical approach has proven itself in studying electron density topology from a low-resolution experimental data set. 52–56 Based on the resulting electron density distribution, we found all intermolecular pair interactions between the considered molecules in the asymmetric unit and its neighbors and then calculated the energy of these interactions according to EML correlation. 57 As expected, the total energy of all intermolecular interactions for one molecule (lattice energy) in a 1 : 8 solid solution at 240 K turned out to be the lowest (33 kcal mol −1 ) compared to crystals of both “pure” cobalt (34 kcal mol −1 ) and “pure” nickel (36 kcal mol −1 ) at 240 K (Table S4†).…”