Syntheses and Structures of New Luminescent Cyclometalated Palladium(II) and Platinum(II) Complexes:  M(Bab)Cl, M(Br−Bab)Cl (M = Pd(II), Pt(II)), and Pd₃Cl₄(Tab)₂ (Bab = 1,3-bis(7-azaindolyl)phenyl, Br−Bab = 1-Bromo-3,5-bis(7-azaindolyl)phenyl, Tab =1,3,5-tris(7-azaindolyl)phenyl)

Abstract

The reactions of blue luminescent ligands 1,3-bis(7-azaindolyl)benzene (BabH), 1-bromo-3,5-bis(7-azaindolyl)benzene (Br-BabH), and 1,3,5-tris(7-azaindolyl)benzene (TabH) with K 2 PdCl 4 and K 2 PtCl 4 have been investigated. Five new luminescent cyclometalated palladium(II) and platinum(II) complexes Pd(Bab)Cl (1), Pt(Bab)Cl (2), Pd(Br-Bab)Cl (3), Pt-(Br-Bab)Cl (4), and Pd 3 Cl 4 (Tab) 2 ( 5) have been synthesized and fully characterized. The molecular structures of 1 and 2, and 3 and 4, are similar. There are however significant variations in the solid-state structures and luminescence of 1 and 2, and 3 and 4. EHMO calculations revealed that it is most likely that the electronic transitions in the Pt(II) complexes are π to π* transitions with significant contributions from d π lone pairs of the Pt(II) center in the π level, and the electronic transitions in the Pd(II) complexes are either d(z 2 ) to π* charge-transfer transitions or π to π* transitions similar to the Pt(II) complexes.

Synthesis and Characterization of Luminescent Cyclometalated Platinum(II) Complexes of 1,3‐Bis‐Hetero‐Azolylbenzenes with Tunable Color for Applications in Organic Light‐Emitting Devices through Extension of π Conjugation by Variation of the Heteroatom

“…[9] By replacing the pyridine rings with azaindoles in the N^C^N ligand, the complexes only emit in low-temperature glass in spite of the relief of angle strain. [10] Recently, our group has reported a new class of luminescent cyclometalated platinum(II) complexes with 2,6-bis(Nalkylbenzimidazol-2'-yl)benzene (bzimb) as the N^C^N ligand and demonstrated that they show green electrophosphorescence in multilayer phosphorescent organic lightemitting devices (PHOLEDs) with a high current efficiency and an external quantum efficiency (EQE) of 38.9 cd A À1 and 11.5 %, respectively. [11a] Although these complexes are unique in that they give rise to intense green phosphorescence, [11] it is envisaged that the utilization of various types of cyclometalated N^C^N ligands with slightly different electronic properties could lead to a gradual variation in the frontier molecular orbital energies to give tunable emission colors.…”

“…A class of pincer platinum(II) complexes of 5‐methyl‐1,3‐bis(benzothiazol‐2‐yl)benzene (bzthb) that shows yellow phosphorescence in solution has also been reported 9. By replacing the pyridine rings with azaindoles in the N^C^N ligand, the complexes only emit in low‐temperature glass in spite of the relief of angle strain 10…”

Synthesis and reactivity of an 2-azabutadiene-based π-conjugated dithioether: Formation of a N,S-ligated molybdenum chelate complex and C,N,S-pincer complexes of palladium and platinum

“…The potential of this polydentate ligands to act as C,N,S-pincer ligand after orthometallation reaction with Pd(II) and Pt(II) has also been demonstrated. In a forthcoming paper we will report on the reactivity of these pincer complexes towards insertion reactions of unsaturated organic molecules [12,13], their electronic structures and their photophysical properties [14][15][16][17][18][19][20][21][22]. …”

2,6-Bis(azaindole)pyridine: reactivity with iron(III) and copper(II) salts

“…Similar torsion angles are observed for the monoclinic (Bowes et al, 2005) and orthorhombic forms (Bessel et al, 1992) of 2,2 H :6 H ,2 HH -terpyridine (tpy) and 2,6-bis(5,6,7,8-tetrahydroquinol-2-yl)pyridine (the torsion angles about the C quinolyl ÐC pyridine bond are À168.5 and 165.7 ; Sasaki et al, 1998). On the other hand, 1,3bis(7-azaindolyl)benzene (bab; Wu et al, 2001) and 1-bromo-3,5-bis(7-azaindolyl)benzene (babBr; Song et al, 2001) crystallize with noncoplanar azaindolyl rings, giving rise to a curved conformation (the torsion angles about the N azaindolyl Ð C benzene bonds are in the 20±45 range).…”