Incorporation of a Fluorine Atom in a Bridging Ligand of Half-Lantern Pt<sup>II</sup><sub>2</sub> Complexes Provides up to 10-Fold Enhancement of Electroluminescence Brightness
Eugene A. Katlenok, Dmitry M. Kryukov, Alexander E. Kurtsevich, K. M. Degtyarenko, Rashid R. Valiev, Oleg V. Levin, Vadim Yu. Kukushkin, Anton V. Rozhkov
Abstract
The binuclear half-lantern platinum(II) complexes [Pt(pbt)(μ-S ∧ N)] 2 (pbtH = 2-phenylbenzothiazole, S ∧ N = benzo[ d ]thiazole-2-thiolate Pt1, 6-fluorobenzo[ d ]thiazole-2-thiolate Pt2, 6-chlorobenzo[ d ]thiazole-2-thiolate Pt3, 6-bromobenzo[ d ]thiazole-2-thiolate Pt4, and 6-iodobenzo[ d ]thiazole-2-thiolate Pt5 ) were synthesized by the treatment of the in situ formed [Pt(pbt)(NCMe) 2 ]NO 3 complex and appropriate benzo[ d ]thiazole-2-thiole in the presence of t BuOK; yield: 51–84%. Complexes Pt1 - 5 exhibit intense red photoluminescence originated from 3 MMLCT state reaching 22% room temperature quantum yields in a CH 2 Cl 2 solution. All complexes display excited-state decay kinetics both in solution and in the solid state; the kinetics was adequately modeled by single exponentials. The complexes display more than 10-fold higher electroluminescence brightness for the F-containing Pt2 (900 cd/m 2 ) and 2-fold higher electroluminescence brightness for the Cl-containing Pt3 (143 cd/m 2 ) compared to the H-substituted complex Pt1 (77 cd/m 2 ). It is argued that this impressive device luminance growth, occurred on formal replacement of H-to-F, is associated with the intermolecular strong hydrogen bonding H···F relevant to the H-bond found in the structure of Pt2 .