Incorporation of a Fluorine Atom in a Bridging Ligand of Half-Lantern Pt^II₂ Complexes Provides up to 10-Fold Enhancement of Electroluminescence Brightness

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 6iodobenzo[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 3MMLCT 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.

Internal conversion induced by external electric and magnetic fields

“…The X–H bond approximation of k IC calculations can be used only for molecules having X–H bonds including organometallic compounds. 16,29,30…”

NIR-II Emission from Cyclometalated Dinuclear Pt(III) Complexes

“…In this regard, half-lantern platinum complexes with C ∧ N cyclometalated ligands and strong intermetallic interactions ( d Pt–Pt ≤ 3 Å) are some of the most representative cases of 3 MMLCT [dσ*­(Pt) 2 → π*­(C ∧ N)] emitters. Among them, mercapto- − or hydroxy- ,, substituted N-heterocycles have been typically used as 4-bond bridging ligands to prepare compounds with bright red emissions that, in some cases, have been successfully implemented in organic light-emitting diodes. − , Recently, α-carboline or 10 H -pyrido­[3,2- b ]­[1,4]­benzoxazine has been used instead so as to push further the emission toward the deep red or NIR spectral region because the use of these rigid bridges confine close Pt···Pt contacts. Besides, comprehensive studies on these and also on related complexes have shown that changes on the chromophoric C ∧ N ligands can push the emission to red as well.…”