A series of [(R'-C^N^C-R'')Pt(L)] complexes with doubly deprotonated cyclometalated R'-C^N^C-R'' ligands (R'-C^N^C-R''=2,6-diphenylpyridine derivatives) functionalized with carbazole, fluorene, or thiophene unit(s) have been synthesized and their photophysical properties studied. The X-ray crystal structures reveal extensive intermolecular π···π and C-H···π interactions between the cyclometalated C^N^C ligands. Compared to previously reported cyclometalated platinum(II) complexes [(C^N^C)Pt(L)], which are non-emissive in solution at room temperature, the carbazole-, fluorene- and thiophene-functionalized [(R'-C^N^C-R'')Pt(L)] (L=DMSO 1-9, C≡N-Ar, 1a-9a) complexes are emissive in solution at room temperature with λ(max) at 564-619 nm and Φ=0.02-0.26. The emissions of the [(R'-C^N^C-R'')Pt(L)] complexes are attributed to electronic excited states with mixed (3)MLCT and (3)IL character. The carbazole/fluorene/thiophene unit(s) allow the tuning of the electronic properties of the [(R'-C^N^C-R'')Pt] moiety, with the emission maxima in a range of 564-619 nm. These are the first examples of organoplatinum(II) complexes bearing doubly deprotonated cyclometalated C^N^C ligands that are emissive in solution at room temperature. In non-degassed DMSO, the emission intensities of 6a-9a are enhanced upon exposure to ambient light. This phenomenon is caused by reacting photogenerated (1)O(2) with a DMSO molecule to form dimethyl sulfone, leading to the removal of dissolved oxygen in solution. Self-assembled nanowires and nanorods are obtained from precipitation of 3a in THF/H(2)O and 8a in DMSO/Et(2)O, respectively. The [(R'-C^N^C-R'')Pt(L)] complexes are soluble in common organic solvents with a high thermal stability (>300 °C), rendering them as phosphorescent dopants for organic light-emitting diode (OLEDs) applications. Red OLEDs with CIE coordinates of (0.65±0.01, 0.35±0.01) were fabricated from 7a or 8a. A maximum external efficiency (η(Ext)) of 12.6% was obtained for the device using 8a as emitter.

Twoclasses of cationic palladium(II) acetylide complexes containing pincer-type ligands, 2,2':6',2''-terpyridine (terpy) and 2,6-bis(1-butylimidazol-2-ylidenyl)pyridine (C^N^C), were prepared ands tructurally characterized. Replacing terpy with the strongly s-donating C^N^Cl igand with two N-heterocyclic carbene (NHC) units resultsi nt he Pd II acetylide complexes displayingp hosphorescence at room temperature and stronger intermolecular interactions in the solid state. X-ray crystal structures of [Pd(terpy)(C CPh)]PF 6 (1)a nd [Pd(C^N^C)(C CPh)]PF 6 (7)r eveal that the complex cations are arranged in ao ne-dimensional stacking structure with pair-likeP d II ···Pd II contacts of 3.349 for 1 and 3.292 for 7.D ensityf unctional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were used to examine the electronic properties. Comparative studies of the [Pt(L)(C CPh)] + analogs by 1 HNMR spectroscopys hed insight on the intermoleculari nteractions of these Pd II acetylidec omplexes.T he strong PdÀC carbene bonds render 7 and its derivatives ufficiently stable for investigation of photo-cytotoxicity under cellular conditions.