Photoluminescence of a New Material: Cyclometalated
C<sup>∧</sup>C* Thiazole-2-ylidene Platinum(II) Complexes
Hendrik Leopold
Alexander Tronnier
Gerhard Wagenblast
Ingo Münster
Thomas Strassner
10.1021/acs.organomet.5b00991.s001
https://acs.figshare.com/articles/journal_contribution/Photoluminescence_of_a_New_Material_Cyclometalated_C_sup_sup_C_Thiazole_2_ylidene_Platinum_II_Complexes/3120337
A new
class of platinum(II) compounds, the 4,5-dimethyl-3-aryl-thiazole-2-ylidene
platinum(II) acetylacetonato complexes, are described. Their efficient
phosphorescent emission at room temperature makes them suitable for
potential applications in organic light-emitting diodes. A new synthetic
pathway that allows the preparation of a broad range of different <i>N</i>-arylthiazole-2-thiones and their subsequent conversion
into the corresponding <i>N</i>-arylthiazolium perchlorate
and hexafluorophosphate salts has been developed. Not only electron-rich
(4-OMe, 4-Me, 3-Me) <i>N</i>-arylthiazoles but also electron-deficient
ligands with a cyano or an ester group could be synthesized. From
commercially available anilines <i>N</i>-arylthiazolium
perchlorate and hexafluorophosphate salts were synthesized via ring-closure
of <i>in situ</i> generated <i>N</i>-aryldithiocarbamate
salts followed by a sulfur-oxidation/-substitution protocol to the
air-stable carbene precursors. All reactions were performed in multigram
scale in good yields. The synthesis of the corresponding platinum(II)
complexes involves generating the corresponding <i>N</i>-arylthiazole-silver(I)-carbene complexes, transmetalation to platinum,
cyclometalation, and reaction with acetylacetonate (acac). Solid-state
structures of two <i>N</i>-arylthiazole-2-thiones, one <i>N</i>-arylthiazolium salt, and three <i>N</i>-arylthiazole-2-ylidene-platinum(II)
complexes complement the analytic characterization including <sup>195</sup>Pt NMR. The unsubstituted complex 4,5-dimethyl-3-phenylthiazole-2-ylidene-platinum(II)-acac
was additionally characterized by 2D-NMR techniques (COSY, HSQC, HMBC,
NOESY). Photoluminescence measurements were performed in amorphous
poly(methyl methacrylate) films and revealed bluish-green emission
maxima (∼500 nm) independent of the electronic structure of
the thiazoles, whereas the variation of the substitution pattern at
the cyclometalating aryl system led to excellent quantum efficiencies
and decay lifetimes of 8.1–21.4 μs.
2016-03-21 16:49:30
cyclometalating aryl system
HSQC
hexafluorophosphate salts
dimethyl
COSY
arylthiazole
HMBC
195 Pt NMR
emission
arylthiazolium perchlorate
complex
Photoluminescence
NOESY