Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Phosphine-assisted bisbenzothienyl iridium(III) complexes: Synthesis,
structures and photophysical properties
Keyan Zhao, Dawei Wang ⁎, Huijun Wang, Zhenzhong Zhu, Yuqiang Ding ⁎
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 9 June 2014
Received in revised form 22 July 2014
Accepted 24 July 2014
Available online 25 July 2014
Phosphine-assisted bisbenzothienyl iridium(III) compounds were synthesized and characterized, and their
structures were confirmed through x-ray crystallography. The TG experiment showed that bisbenzothienyl
iridium(III) compounds have excellent stability. In terms of photophysical properties, these complexes have
the typical green emission.
©
2014 Elsevier B.V. All rights reserved.
Keywords:
Iridium
Benzothiophene
Phosphine
Photoluminescence
Catalytic reactivity
The design and synthesis of the new Ir(III) complexes are currently
of great interest because of their unique photophysical properties for
OLED applications [1,2]. Among these complexes, the neutral ones are
much more suitable for OLED applications than ionic iridium(III) com-
plexes are, due to the process of vapor deposition [3,4]. Moreover, neu-
tral complexes and particularly heteroleptic complexes are of interest
because they typically exhibit outstanding optical properties [5,6].
Our research in organometallics is primarily focused on
cyclometalated Ir(III) complexes, using amides as auxiliary ligands. Re-
cently, we reported a number of amidate Ir(III) complexes containing
phenylpyridyl (ppy) and phenylquinolyl (pq) cyclometalating ligands
2 3
recrystallization, the (bt) Ir(PAr ) (2) complexes were obtained with
moderate to good yields (Scheme 1) [9].
Crystal structure of 2a
Given the synthesis of phosphine-assisted bisbenzothienyl
iridium(III) complexes, the molecular structure of 2a was determined
by x-ray diffraction, as shown in Fig. 1. Single-crystal analysis reveals
that compound 2a belongs to the P2 /c space group. Its crystallographic
1
asymmetry unit contains one Ir complex (Fig. 1).
2 3
Meanwhile, the photophysical characterization of the (bt) Ir(PAr )
[
7]. These complexes demonstrated photoluminescent efficiencies and
complexes (2) was explored (Fig. 2). The maximum absorption wave-
lengths of the complexes were observed at approximately 320 nm,
being dramatically different from those of Ir(III) complexes with amides
as auxiliary ligands.
The phosphorescence quantum yields (ΦPL) of these Ir(III) com-
plexes (2) were investigated at room temperature (as shown in
Table 1). To our delight, the wavelengths of solution photoluminescence
(PL) of complexes were observed at approximately 541 nm, which fall
into the green-light region.
color bands [8], but amide auxiliary ligands have not. Consequently,
we must turn our attention to the search for other auxiliary ligands
with which to synthesize the heteroleptic complexes and harness
their excellent photophysical properties. Therefore, as part of our con-
tinuing study of auxiliary ligands, we report on our study of the synthe-
sis, characterization, as well as the structural and photophysical
properties of these phosphine-assisted bisbenzothienyl (bt) iridium(III)
complexes.
According to the literature, dichloro-bridged complexes [(bt)
have been synthesized from bt ligand with IrCl ·3H O. Subsequently,
chloro-bridged dimer and phosphine ligand were placed in a Schlenk
tube containing CH Cl as solvent under a nitrogen atmosphere. The re-
action mixture was stirred at room temperature for 6 h. After
2
IrCl]
2
To determine the thermal stabilities of complexes, TG experiments
were carried out and the thermal curves were as shown in Fig. 3. In
most cases, the complexes showed a weight loss of approximately 10%
at 300 °C, which is partially attributable to the oxidation of triphosphine.
The experiment shows that these Ir(III) complexes with triphosphine
ancillary ligand have good thermal stability.
3
2
2
2
Finally, with these complexes in hand, we want to expand their ap-
plications in the area of catalysis. The transfer dehydrogenation reaction
of 1-phenylethanol with styrene was tested. First, we examined the
⁎
(
Y. Ding).
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1
Zhao, Keyan
