Rationally Designed Blue Triplet Emitting Gold(III) Complexes Based on a Phenylpyridine-Derived Framework

Article abstract of DOI:10.1002/chem.201605567

A series of blue-emitting phosphorescent mono-cyclometalated Au^III complexes have been successfully synthesized. Tailoring the substitutions on the phenylpyridine (ppy) ligand scaffold with electron-withdrawing fluorine groups on the phenyl ring to achieve stabilization of the HOMO and an electron-donating dimethylamino group on the pyridine ring to destabilize the LUMO resulted in a large energy gap and bestowed on the gold(III) complexes high-energy emission and high quantum efficiencies. The results of cyclic voltammetry studies suggested a predominantly redox event localized on the cyclometalated ligand. Thermogravimetric analysis of selected complexes revealed a high stability up to 280 °C, thus the complexes are suitable for device fabrication through vacuum-deposition. Photophysical investigations performed on all the derivatives revealed phosphorescence emission in neat solid, solution, doped in poly(methyl methacrylate) (PMMA) films at room temperature as well as in rigidified glass media (2-MeTHF) at 77 K. A high photoluminescent quantum efficiency of 28 % was obtained for a complex in PMMA, the highest quantum yield reported for a blue-emitting gold(III) complex.

Full text of DOI:10.1002/chem.201605567

A Journal of
Accepted Article
Title: Rationally Designed Blue Triplet Emitting Gold(IIII) Complexes
Based on Phenylpyridine Derived Framework
Authors: Michael Bachmann, Jasmin Terreni, Olivier Blacque, and
Koushik Venkatesan
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Chem. Eur. J. 10.1002/chem.201605567
Link to VoR: http://dx.doi.org/10.1002/chem.201605567
Supported by

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
Rationally Designed Blue Triplet Emitting Gold(III) Complexes
Based on Phenylpyridine Derived Framework
Michael Bachmann, Jasmin Terreni, Olivier Blacque, and Koushik Venkatesan*[a]
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
Abstract:
A
series
of
blue
emitting
phosphorescent
successfully
those of platinum or iridium, which is beneficial for the radiative
decay of the triplet excited states.[3] In recent past, more
attention in exploration of the basic photophysical properties of
Au(III) complexes has gained increased exploration for
applications as efficient small molecule phosphors in OLED
devices.[4]
monocyclometalated
Au(III)
complexes
were
synthesized. Tailoring substitutions at the phenylpyridine (ppy)
ligand scaffold with the electron withdrawing fluorine groups at the
phenyl ring to achieve stabilization of the HOMO and electron
donating dimethylamino group on the pyridine ring to destabilize the
LUMO resulted in a large energy gap and bestowed the gold(III)
complexes with emission at high energies and high quantum
efficiencies. Cyclic voltammetry (CV) studies are suggestive of a
predominantly cyclometalated ligand localized redox event.
Thermogravimetric analysis (TGA) of selected complex displayed a
high stability up to 280 °C, making the complexes suitable for device
fabrication through vacuum deposition. Photophysical investigations
performed for all the derivatives displayed phosphorescence
emission in neat solid, solution, doped in poly(methyl methacrylate)
(PMMA) films at room temperature as well as in rigidified glass
media (2-MeTHF) at 77 K. A high photoluminescent quantum
efficiency up to 28% was obtained for a complex in PMMA, the
highest quantum yield reported for a blue emitting gold(III) complex.
To overcome the aforementioned disadvantages, a successful
strategy was pursued by the group of Yam that involved the use
of strong field ligands with good σ-donating properties as
ancillary ligands in order to decrease the probability for thermal
population of non-emissive d–d states.[5] Utilizing such an
approach, Yam reported the first luminescent gold(III)
complexes in 1990 and later followed it by the development of
room temperature luminescent biscyclometalated gold(III)
complexes.[6] The tridentate ligand system has been further
exploited by other groups to access new luminescent gold(III)
complexes.[7] Based on the initial impetus and subsequent
studies, our group had recently demonstrated phenyl pyridine
(ppy) based mono-cyclometalating ligands as
a promising
framework for obtaining stable, luminescent gold(III)
complexes.[8] Since phenyl is a better σ-donating ligand than
pyridine, the introduction of a cyclometalating ppy instead of the
bipyridine (bipy) was assumed to further increase the energy
level of the d-d-states. In addition to the cyclometalation,
employment of strong field aromatic stabilized carbanions as
ancillary ligands was expected to sufficiently destabilize the
metal centered (MC) transition to higher energies thereby
creating a conducive metal-ligand environment for effective
mixing of singlet-triplet states and radiative relaxation from the
Introduction
Investigation of tunable room temperature phosphorescent metal
complexes have gained a widespread interest in the last
decennaries
following
the
near-commercialization
of
cyclometalated iridium(III) and platinum(II) complexes for
applications in OLEDs (organic light emitting diode).[1a-e] While
gold(I) complexes have intensively been studied in their
photochemical properties[1f,1g] and have shown to be active in
photoredox catalysis recently[1h,1i], gold(III) complexes remain
underexplored for their luminescent properties in comparison to
the isoelectronic platinum(II) and iridium(III) counterparts which
can be ascribed to a number of reasons.[2] These reasons
mostly include the moderate stability of organogold(III)
compounds and the low-lying d-d ligand field (LF) states of
gold(III) complexes, with the latter one known to deactivate
excited-states non-radiatively. On the contrary, the spin-orbit
coupling constant of gold (ζ = 5100 cm-1) is even higher than
triplet manifold. Adopting such
a strategy yielded stable
complexes with long-lived emission in solution at room
temperature and tunable emission energies with λmax centered
from 490 nm to 590 nm depending on the electronic character of
the arylpyridine derivative. Although access to green and red
emitting complexes could be successfully achieved, gold(III)
complexes based photoactive materials displaying emission in
the blue / deep blue region of electromagnetic spectrum is
lacking. One of the main problem currently being faced is the
production of high-quality blue-emitting OLEDs in general.[9]
There are three challenges that have to be overcome
concerning the development of efficient blue triplet emitters.
Firstly, the chromaticity of the most available blue phosphor is
not a true blue color (λmax 435 nm), which gives a poorer color
spectrum for applications in full color OLED displays. Secondly,
the emission quantum efficiency of blue phosphors is far lower
than green and red phosphors, which has significant
consequences on the quality of the white light, especially in the
case of cold white light, which requires a larger share of the blue
part of the electromagnetic spectrum. Finally, the working
[a]
M. Bachmann, J. Terreni, Dr. O. Blacque, Dr. K. Venkatesan
Department of Chemistry
University of Zurich
Winterthurerstrasse 190
CH-8057, Zurich (Switzerland)
Fax: (+41)446356803
E-mail: venkatesan.koushik@chem.uzh.ch
Supporting information for this article is given via a link at the end of
the document.((Please delete this text if not appropriate))
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
lifetime of most of the blue dyes in OLEDs are often thousands
of hours shorter than those of green and red counterparts, which
is a property relevant to their phosphorescence efficiency and is
influenced by their molecular tailoring and device construction.
The reason for the relatively faster degradation of the blue dyes
can be attributed to the requirement of higher excitation energy.
The higher in energy an excited state is situated, the more likely
it is that a reactive potential lies in between this and the ground
state. In short, the emissive substance is more likely to
decompose.[10] The poor stability of blue phosphors
unfortunately makes such displays visually much faster distorted
than would be acceptable for a commercially viable device.
Therefore, investigations pertaining to efficient and stable blue
triplet emitters are of high demand in order to drastically improve
the performance of the OLED devices and are crucial for its
additionally also obtain a closer insight into the effects of the
different substitutions of the C^N cyclometalated ligands on the
photoluminescent properties of the corresponding Au(III)
complexes, which remains rather underdeveloped.
Results and Discussion
Synthesis and characterization
Compounds 1–4 were synthesized as colorless solids in 39–
62% yield starting from the different cyclometalated
cis(N^C)AuCl2 derivatives and subsequent substitution of the
chlorides with pentafluorophenyl ligand in the case of complexes
1, 3, 4 and ethynyl-4-fluorophenyl for complex 2 according to the
synthetic strategy shown in Scheme 2. All the final compounds
were characterized by 1H, 13C, 19F NMR and elemental analysis.
The successful coordination of the pyridine derivatives to the
mercury center could be verified due to the absence of the
proton resonance in the 1H NMR spectra with the other proton
resonances showing any significant shift. The later
transmetallation step in order to obtain the corresponding gold
precursor, showed a distinct downfield shift of around 0.6–
0.8 ppm from the α proton on the pyridine due to the deshielding
of the proton after coordination to the nitrogen. In the final
products, 19F NMR measurements revealed the efficacious
bonded ancillary aryl or alkyne ligands. As expected the spectra
showed additional six different resonances for the two
commercial application. Although,
a Au(III) blue emitting
phosphor is known based on a tridentate biscyclometalated
system, it possesses only a weak emission.[11a] Initial studies in
our group on the unsubstituted ppy Au(III) complexes showed
the origin of the emission to arise from an intraligand charge
transfer (3ILCT) [π-π*] perturbed by the metal center. This was
further confirmed by DFT and TD-DFT calculations that revealed
the HOMO to be almost entirely localized on the phenyl part of
the cyclometalated ligand and the LUMO at the pyridine moiety
due to the better accepting properties. Based on the above
information, we approached to rationally alter the ligand scaffold
of the monocyclometalated gold(III) complexes[11b] to achieve the
desired blue emission.[8a] As illustrated in Scheme 1, addition of
electron withdrawing substituents such as F, CF3 and OCF3 on
the phenyl group was expected to result in a decreased energy
level of the HOMO and substitution of the pyridine with an
electron donating group such as dimethylamine increasing the
corresponding LUMO state, respectively.
pentafluorophenyls
and
two
signals
for
the
4-
fluorophenylacetylene, respectively, which is in good agreement
with the two unequal trans standing ligands to the
cyclometalating moiety. Due to the absence of NOE effect,
overlap of signals and coupling with different fluorine atoms, only
undefined small multiplets were observed for the carbon signals
of the pentafluorophenyl ligand in the 13C NMR.
Scheme 1. Concept of hypsochromic shift caused by increase of HOMO-
LUMO gap.
Scheme 2. Synthetic pathway for complexes 1–4.
Besides, fluorinated compounds also bring along several
advantages. The increased electronegativity of the ligands
profits in a better overlap towards the low-lying Au(III) orbitals
In addition, the crystal structure of complex 4 was determined by
an X-ray diffraction study (Figure 1) on suitable single crystals,
and therefore resulting in
a higher stability of the final
which were obtained by slow diffusion of hexane into
a
compounds. The bulky substituents, such as CF3 or OCF3 hinder
the stacking of the compounds and can possibly inhibit self-
quenching effects and further, the sublimation for thin film
deposition is enhanced.[12] Based on the above concepts, we
deemed it possible to achieve efficient blue triplet emitters and
dichloromethane (CH2Cl2) solution containing small
a
concentration of the compound. Crystallographic data and
selected bond distances and angles are given in Table 1 (further
data are given in Supporting Information). The Au(III) complex
possesses a square planar geometry. The cyclometalated ligand
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
is almost planar with the angle between the mean planes of the
phenyl and pyridine rings of the cyclometalated ligand only being
1.44(12)°. The methyl substituents of the dimethylamino group
are coplanar with the pyridine ring and the corresponding carbon
atoms deviate from the mean plane by only 0.043(3) and
0.158(3) Å. The pentafluorophenyl ligands lie almost
perpendicular to the phenylpyridine. The angles between the
mean planes of the C6F5 rings and the pyridine ring are
71.96(13) and 71.74(13)°. The Au–C bond length between the
metal center and the pentafluorophenyl ligand is slightly shorter
in the case of the ligand trans to the pyridine nitrogen atom than
in the case of the ligand trans to the 2,3,4-fluorophenyl part
(2.014(2) vs. 2.080(3) Å) which is in a good agreement with the
stronger trans influence of phenyl vs. pyridine ligand in general.
The crystal packing of the structure exhibits some C–H…F and
Photophysical properties
The UV/Vis absorption spectra of 1–4 in CH2Cl2 at 298 K are
shown in Figure 2. All four complexes exhibit two strong bands
at wavelengths below 300 nm and a moderate intense band at
310–360 nm. Based on the spectroscopic studies, the
absorption bands are mainly assigned to origin of an admixture
of metal-perturbed 1ILCT. Concentration dependent absorption
studies of all the complexes in CH2Cl2 (c ≈ 10-6–10-4 mol dm-3)
displayed no development of an additional low energy band or
shifting in the λmax supporting the absence of any aurophilic
interactions in solution and precluding excimeric metal to metal
charge transfer (3MMLCT) transitions. Varying the ancillary
ligands on the cyclometalated gold center had no distinct effect
on the absorption wavelengths except only a small bathochromic
shift of the high energy absorption band was observed which is
due to the increased electron density at the phenylacetylene
compared to the pentafluorophenyl counterpart.
C–F…π
intermolecular interactions, the shortest H…F and
F…centroid contacts are 2.57 and 3.065(2) Å, respectively, but
no π…π or Au…Au interactions (the shortest Au…Au distance is
5.4210(3) Å) were observed.
Figure 1. X-ray crystal structure of 4 with selective atomic numbering scheme.
Thermal displacement ellipsoids are drawn at the 30% probability level.
These complexes were found to have overall the same thermal
stability. Thermogravimetric analysis (TGA) of complex
1
displayed an onset of total degradation at 280 °C (Figure S1).
Such high thermal stability makes these classes of complexes
suitable for OLED device fabrication through vacuum deposition
Figure 2. UV/Vis absorption spectra of complexes 1–4 in CH2Cl2.
Increasing solvent polarity from cyclohexane to acetonitrile leads
only to a small hypsochromic shift (λ ∼ 10 nm) for complex 1
indicating the ground state has more polar constitution as
compared to the excited state (Figure S2). Complexes 1–4
exhibit strong emission in fluid solution at room temperature,
doped in PMMA and in rigidified glass media (2-MeTHF) at 77 K.
The spectroscopic data for complexes 1–4 are given in Table 3
and the emission profiles in different media for all the complexes
are shown in Figure 3–5. The emission wavelengths were not
significantly influenced by their different electron withdrawing
groups and further didn’t display remarkable shifts between
solution and PMMA films except for complex 4 which showed a
much broader and less structured emission band in fluid solution
at room temperature compared to the other derivatives. To verify
that no excimeric states were formed, additional concentration
dependent measurements were performed. The outstretched
emission profile didn’t change after dilution in CH2Cl2, declined
in toluene and disappeared completely in THF indicating the fact
that this behavior is ascribed to the inherent nature of this
Table 1. Selected bond distances (Å) and angles (°) for complex 4.
Au1-N1
2.054(2)
2.048(3)
2.014(2)
2.080(3)
95.84(9)
80.46(9)
176.29(9)
175.74(9)
95.34(10)
88.37(10)
Au1-C7
Au1-C20
Au1-C14
N1-Au1-C14
C7-Au1-N1
C7-Au1-C14
C20-Au1-N1
C20-Au1-C7
C20-Au1-C14
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
compound and is not induced by intermolecular interactions
(Figure 6). Further investigations in the future are required to
ascertain the origin of this behavior. Supplementary
measurements such as excitation spectra and concentration
dependence of the PMMA films can be found in the supporting
information (Figure S3, S4). A small bathochromic shift of the
emission wavelength was observed while increasing the doped
wt% of complex 1 from 2% to 30%, which can be attributed to
minor intermolecular quenching effects.
due to the favorable accepting properties. As hypothesized
inclusion of an electron withdrawing substituent at the phenyl
decreased the energy level of the respective HOMO’s and
substitution at the pyridine with the electron donating NMe2
increases the levels of the LUMO’s, respectively. Overall the
emission showed hypsochromic shifts with highest energy
emission maxima in the range λmax = 420–438 nm. This
corresponds to a blue shift of up to 27 nm in comparison to the
parent phenylpyridine analogue.
On the basis of the above observations and previous studies on
the unsubstituted ppy derivatives in our group, the origin of the
emission is assigned to arise from an intraligand charge transfer
(ILCT) [π-π*] perturbed by the metal center. Stokes shifts and
lifetimes in the lower microsecond range strongly imply that the
emission takes place from the triplet state. DFT and TD-DFT
calculations (For a detailed discussion, see later section on DFT
and TD-DFT calculations) on ppy Au(III) complexes further
underscores our presumption that the corresponding admixtures
of the HOMO’s is almost entirely localized on the phenyl part of
the cyclometalated ligand and the LUMO’s at the pyridine moiety
Figure 7 shows representative 1931 Commission Internationale
de L'Eclairage coordinates (CIE x,y) calculated from the
photoluminescence spectrum in PMMA and the corresponding
values are listed in Table 2. For example, devices using the
nowadays leading FIrpic dopant as the chromophore usually
exhibit CIE coordinates around (0.18,0.33).[13] The CIE
coordinates of these complexes, which remain in the dimension
up to (0.15,0.13) are much closer to the desired true-blue color
(0.14,0.08).
Figure 3. Emission spectra of complexes 1–4 in 2-MeTHF at 77 K.
Figure 4. Emission spectra of complexes 1–4 in 2wt% in PMMA films.
Figure 5. Emission spectra of complexes 1–4 in solution.
Figure 6. Normalized emission spectra of 4 in different solvents.
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
Table 2: Emission coordinates of 1–4 on the CIE-1931 chromaticity diagram.
Complex
X / Y
1
2
3
4
0.1565 / 0.1679
0.1480 / 0.1557
0.1488 / 0.1737
0.1540 / 0.1341
Figure 7. CIE-1931 diagram of 1–4 in 2wt% in PMMA films.
Table 3. Photophysical properties of complexes 1–4.
Absorption (CH2Cl2)
Emission
max/nm (τ0/µs)
Complex
λ
max/nm (ε/M-1cm-1)
Medium (T/K)
λ
φ
em (%)
kr [×103s-1]
knr [×105s-1]
230 (36655)
276 (31525)
331 (7715)
glass (77)
PMMA (298)
DCM (298)
431, 455, 486, 527 sh
435, 463, 489 sh (1.15)
435, 464, 489 sh
-
1
28.1
243.5
6.3
275 (38596)
330 (12117)
glass (77)
PMMA (298)
DCM (298)
430, 459, 486, 525 sh
435, 462 (0.18)
435, 464, 490 sh
-
2
3
4
3.0
166.7
21.5
86.3
53.9
4.5
230 (30820)
277 (27866)
324 (7487)
glass (77)
PMMA(298)
DCM (298)
429, 458, 487, 521 sh
436, 464, 491 sh (2.09)
439, 464, 495 sh
-
4.5
230 (30820)
274 (26981)
324 (8745)
glass (77)
PMMA (298)
DCM (298)
431, 451, 481, 524 sh
434, 463 (3.21)
436, 465, 487
-
27.6
2.3
Electrochemical properties
Cyclic voltammetry investigations of all four complexes
displayed irreversible reduction peaks in the range of -2.04 to -
2.40 V (vs Fc0/+ couple) in DMF at room temperature (Table 4).
No oxidation peak was observed. Considering the congruence of
the reduction peak potentials among the diverse compounds,
the reduction event is referred to be a predominately ligand
centered electrochemical process.
DFT and TD-DFT calculations
TD-DFT calculations were carried out on the DFT optimized
ground state geometry of complexes 1–4 (see Computational
Details and Supporting Information). In the case of 1, 3 and 4,
they clearly confirm the spectroscopic evidences that the three
moderate to intense absorption bands experimentally observed
predominantly arise from an intraligand charge transfer 1ILCT
within the cyclometalated N^C ligand. The most important
contributions to the calculated π→ π* transitions come from the
HOMO→LUMO, HOMO-1→LUMO, and HOMO→LUMO+2
excitations involving four frontiers molecular orbitals mainly
localized on the N^C ligand and the metal center (Figure 8,
Figures S9, S11-S13, S16, S17). It is slightly different for the
alkyne containing complex 2. The first two singlet-singlet S0-S1
and S0-S2 transitions for 2 (331.6 and 325.0 nm, oscillator
strengths f = 0.139 and 0.441, respectively) resulting into a
moderate intense absorption band, are ligand-to-ligand 1LLCT
transitions coming from the HOMO→LUMO and HOMO-
Table 4. Electrochemical potentials for complexes 1–4 in 0.1 M [nBu4N][PF6]
(glassy-carbon electrode; E vs Fc0/+; scan rate = 100 mV/s; 20°C, DMF).
Complex
Reduction Epc/V vs Fc0/+
1
2
3
4
-2.04
-2.13
-2.11
-2.40
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
1→LUMO excitations: the occupied frontier orbitals being mainly
located on the alkyne ligands (and on the dimethylaminopyridine
ligand for HOMO-1) and the unoccupied orbital on the
cyclometalated ligand. The two other bands in the 240 – 280 nm
conformation will be noted 2B in the manuscript, while the fully
optimized structure will be 2 or 2A. The calculations revealed
that 2B is only 0.25 kcal/mol higher in energy than 2A without
energy barrier on the way indicating a free rotation of the alkyne
ligands in solution at room temperature, experimental conditions
of the UV/Vis studies. TD-DFT calculations as single point
calculations on all studied conformations of 2 show that the
1LLCT absorption band formed by the two S0-S1 and S0-S2
transitions of 2A decreases in intensity with the rotation of the
C6H4F groups from almost coplanar to perpendicular (2B) to the
cyclometalated ligand (Figure S14, S22). The oscillator strength
of the S0-S1 and S0-S2 transitions decrease and the first
significant transition becomes S0-S3 (312.7 nm, f = 0.249), a
1ILCT(N^C) transition arising from the HOMO-2→LUMO excitation.
The two strong bands at wavelengths below 300 nm remain
from mixed origins but are calculated to be shifted closer to each
other.
region correspond to a mixing of 1ILCT(N^C)
1LLCT(alk→N^C) transitions.
Nevertheless,
,
1ILCT(alk) and
the geometry
optimization of complex 2 suggested that the C≡C-(C6H4F)
alkyne ligands are relatively free to rotate around the Au – C
bond. The fully optimized geometry (without constraint) of
complex
2
exhibits
a
relatively planar conformation
characterized by the two torsional angles N1-Au1-C1-C2 and
C3-Au1-C4-C5 of 25.1 and -4.7°, respectively (Figure S10). A
relaxed potential energy surface scan (with geometry
optimization at each point) was performed with two variables as
the previously defined torsional angles X-Au-C-C (X = N or C).
The two variables were varied together from 0 to 90° (step of
15°) to reach a final conformation for which the terminal C6H4F
benzene rings are perpendicular to the (N^C) plane. The latter
Figure 9. Spatial plots of selected frontier orbitals of the DFT optimized
ground state of 1 and 2 (2A).
Figure 8.
Singly occupied molecular orbitals (top:SOMO, middle: SOMO-1)
obtained by restricted open-shell single pointcalculations on the
optimized triplet state geometries, and spin densitysurfaces (bottom)
for the optimized triplet states of 1–4 (the positive spin densities are
shown in blue and the negative ones are in green).
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
Table 5. Selected singlet (S1, and Sn with oscillator strength f > 0.1) and triplet Tm excited states (m = 1-3) calculated with TD-DFT/CPCM (in dichloromethane):
vertical excitation energies (nm), transition coefficients (c > 0.2), orbitals involved in the transitions, and oscillator strengths f for compounds 1–4. * H = HOMO, L
= LUMO
1
2A
2B
3
4
S0–Sn
n = 1
n = 2
n = 5
n = 1
n = 2
n = 6
n = 1
n = 3
n = 4
n = 1
n = 3
n = 6
n = 1
n = 2
309.6 (f = 0.170)
H→L (c = 0.68) a
331.6 (f = 0.139)
H→L (c = 0.69)
331.5 (f = 0.000)
H→L (c = 0.69)
303.5 (f = 0.223)
H→L (c = 0.67)
306.0 (f = 0.195)
H→L (c = 0.69)
283.2 (0.166)
H-1→L (0.65)
325.0 (0.441)
H-1→L (0.69)
312.7 (0.249)
H-2→L (0.69)
290.3 (0.256)
H-1→L (0.68)
284.8 (0.224)
H-1→L (0.66)
n = 11
265.2 (0.160)
H→L+2 (0.40)
H-6→L (0.38)
279.4 (0.308)
H→L+1 (0.59)
290.0 (0.154)
H-3→L (0.67)
261.6 (0.318)
H→L+2 (0.48)
H-4→L (0.24)
H-2→L (0.20)
258.3 (0.592)
H→L+2 (0.59)
n = 6
n = 9
n = 7
n = 5
n = 7
n = 7
n = 8
n = 16
264.0 (0.356)
H→L+2 (0.46)
276.2 (0.365)
H-1→L+1 (0.63)
276.4 (0.239)
H→L+2 (0.65)
260.7 (0.158)
H-3→L+1 (0.28)
H→L+2 (0.25)
235.2 (0.220)
H-1→L+2 (0.65)
n = 13
260.0 (0.104)
258.1 (0.228)
273.1 (0.155)
259.1 (0.309)
H-4→L (0.31)
H-1→L+1 (0.26)
H-5→L+1 (0.21)
H-2→L+1 (0.37)
H→L+6 (0.32)
H→L+ (0.22)
H-1→L+2 (0.62)
H-1→L+7 (0.20)
H→L+2 (0.33)
H-5→L+1 (0.30)
H-4→L+1 (0.22)
n = 15
n = 16
n = 14
n = 16
n = 8
n = 15
237.9 (0.288)
H→L+3 (0.48)
257.6 (0.196)
H-2→L+1 (0.33)
271.1 (0.155)
H-4→L (0.43)
H-3→L+1 (0.25)
244.1 (0.152)
H-1→L+2 (0.52)
H-6→L (0.39)
n = 10
236.7 (0.115)
250.1 (0.273)
265.9 (0.422)
H→L+3 (0.44)
H-1→L+2 (0.36)
H→L+4 (0.41)
H-1→L+2 (0.36)
H→L+3 (0.22)
H-2→L+1 (0.63)
n = 17
n = 11
247.9 (0.177)
H-1→L+2 (0.37)
H-1→L+4 (0.22)
261.8 (0.184)
H-4→L (0.51)
H-5→L (0.45)
n = 15
n = 17
255.1 (0.660)
H→L+3 (0.63)
247.9 (0.110)
H-3→L+1 (0.38)
H-5→L (0.30)
H-1→L+3 (0.23)
n = 19
245.1 (0.466)
H-1→L+3 (0.55)
S0–T1
S0–T2
413.0
H-1→L (0.59)
H-6→L+2 (0.20)
419.6
H→L (0.29)
416.1
H-3→L (0.56)
418.7
H-1→L (0.61)
408.2
H-1→L (0.61)
389.2
414.4
405.2
381.0
391.5
H→L (0.66)
H-1→L (0.30)
H-1→L+2 (0.36)
H→L+2 (0.35)
H-7→L+5 (0.20)
H→L (0.65)
H→L (0.66)
S0–T3
330.6
408.7
400.9
328.3
327.7
H→L+2 (0.53)
H-3→L (0.36)
H→L+3 (0.43)
H-6→L+6 (0.21)
H→L+2 (0.58)
H→L+2 (0.61)
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
The emission spectra recorded in dichloromethane at room
temperature indicated similar luminescent properties for all
complexes with maximum emission wavelengths in the narrow
range of 435 – 439 nm. The lowest singlet-triplet T1–S0 energies
obtained from the ground state structures of 1–4 are in a good
agreement with the experimental data (Table 5). Indeed, the
calculated energy values are very close to each other, in the
range 408 – 418 nm, underestimating the experimental data by
about 20 nm only. The first triplet excited state T1 of 1, 3 and 4
originates from the HOMO-1→LUMO excitation. The S0-T1
transition can be assigned as an intraligand charge transfer
3ILCT between π and π* orbitals of the cyclometalated ligand
N^C. Taking into account the ground state geometry of 2 (2A),
the first triplet excited state T1 originates from the
HOMO→LUMO excitation and the corresponding S0-T1 transition
(419.6 nm) can be assigned as a ligand-to-ligand charge
gold(III) complexes demonstrated in this work paves way for the
development of new efficient blue gold(III) triplet emitting
molecules and further strengthens their prospects for OLED
applications.
Experimental Section
General procedure
All manipulations requiring inert atmosphere were carried out
using standard Schlenk techniques under dinitrogen. 1H, 13C{1H}
and 19F NMR spectra were recorded on Bruker 400 MHz and
500 MHz spectrometers. Chemical shifts (δ) are reported in
parts per million (ppm) referenced to tetramethylsilane (δ 0.00)
ppm using the residual proton solvent peaks as internal
standards (1H NMR experiments) or the characteristic
resonances of the solvent nuclei (13C NMR experiments). 19F
NMR was referenced to CFCl3 (δ 0.00) ppm. Coupling constants
(J) are quoted in Hertz (Hz) and the following abbreviations are
used to describe the signal multiplicities: s (singlet); d (doublet); t
(triplet); q (quartet); quint (quintet); sext (sextet); sept (septet); m
(multiplet). Proton and carbon assignments have been made
using routine one and two dimensional NMR spectroscopies
where appropriate. Elemental microanalysis was carried out with
Leco CHNS-932 analyzer. TLC analysis was performed on
precoated Merck Silica Gel60F254 slides and visualized by
luminescence quenching either at (short wavelength) 254 nm or
(long wavelength) 365 nm. Chromatographic purification of
products was performed on a short column (Length 30.0 cm:
diameter 3.0 cm) using silica gel 60, 230–400 mesh using a
forced flow of eluent. UV/Vis absorption measurements were
3
transfer LLCT(alk→N^C) between π orbitals of the alkynes ligands
and π* orbitals of the cyclometalated ligand. The 3ILCT(N^C)
triplet state is computed as T3 (408.7 nm) while T2 (414.4 nm)
3
arises essentially from a LLCT(alk→N^C) transition like the lowest
triplet state T1. The energy and character of the first three triplet
excited states of complex 2 were also investigated in relation
with the rotation of the terminal C6H4F groups of the alkyne
ligands (Tables S1-S2). The study revealed that the 3ILCT(N^C)
triplet state, T3 for the coplanar ground state geometry 2A,
becomes the emitting triplet state T1 for the perpendicular
conformation 2B. In fact, T1 exhibits mainly a 3LLCT(alk→N^C)
character as long as the dihedral angle variables remains in the
interval 0 – 30° but that character rapidly vanishes to disappear
from 45° (Figure S23). From that point, T1 exclusively originates
from a 3ILCT(N^C) transition arising from the HOMO-3→LUMO
excitation. The two other calculated lowest triplet excited states
3
3
carried out on
a
Perkin-Elmer Lambda 35 UV/Vis
T2 and T3 come from mixed LL and IL transitions. The lowest
triplet state structure of each complex was optimized by
unrestricted calculations. The spin density surfaces and the
singly occupied molecular orbitals obtained from restricted open
shell calculations are displayed on Figure 9. The results confirm
spectrophotometer. Emission spectra were acquired on Perkin
Elmer spectrophotometer using 450 W Xenon lamp excitation by
exciting at the longest-wavelength absorption maxima with the
excitation slit width 5 nm and emission slit width 10 nm. Absolute
quantum yields φem were determined at 298 K in thin films using
an integrating sphere on the Edinburgh spectrophotometer
FLS920 (estimated uncertainty ± 15 %). YAG:Ce (powder) was
3
the ILCT(N^C) origin of the emission but also highlight the role of
the dimethylaminopyridine moiety in the luminescent process.
used as
a
calibration reference with φem
=
97 %.
Phosphorescent lifetimes in thin films were measured on the
Edinburgh laser flash photolysis spectrophotometer LP920 with
a Nd:YAG 355 nm laser as an excitation source fitted with a
single monochromator. Photo excited emission color CIE-1931
chromaticity diagrams were determined using normalized
emission spectra and the ColorCalculator Version 5.31 from
Osram Sylvania. Cyclic voltammograms were measured with a
Metrohm 757 VA Computrace with a glassy carbon electrode (d
= 2mm) with a Pt counter electrode versus Ag/AgCl reference
electrode.
Conclusions
It is demonstrated through monocyclometalated compounds of
the type cis-[(N^C)AuL2] (L = aryl, alkyne) for the first time that
true blue phosphorescent emission based on gold(III) complexes
can be achieved with the highest efficiency reported so far. They
display luminescence at room temperature in fluid solution and
their emission wavelengths can be tuned by changing the
substituents on the cyclometalating ligand. Of particular interest
is complex 1 with the excellent quantum efficiency of 28% in
PMMA and the high stability making them suitable for vacuum
deposition for enabling OLED applications. DFT calculations in
conjunction with experimental work have ascertained the relative
stability of the complexes and the nature of the triplet excited
state. The stability and ease of tunability of the blue emitting
All starting materials were purchased from commercial sources
and used as received unless otherwise stated. All chemicals
were of reagent grade and the solvents used for synthesis were
of analytical grade.
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
2-bromo-4-(N,N-dimethylamino)pyridine
Bis(chloro)-2-(3-trifluoromethylphenyl)-4-(N,N-
In a Schlenk flask containing dry hexane (40 mL) at –5°C,
dimethylethanolamine (4.90 mL, 49 mmol) was added. 2.5 M
nBuLi (39 mL, 97.5 mmol) was added and the reaction mixture
was stirred for 1 h. Further, dimethylaminopyridine (2.95 g, 24.2
mmol) was added to give an orange mixture and this mixture
was stirred at 0°C for 2 h. After, the reaction mixture was cooled
to –80°C and tetrabromomethane (20.0 g, 60.4 mmol) dissolved
in dry hexane was added to the reaction mixture. After stirring
for 1 h, the reaction mixture was quenched with H2O resulting in
a complete black solution. The aqueous phase was extracted
with Et2O and the combined organic phases were dried over
MgSO4. Evaporation of the solvent in vacuo delivered the crude
product. The crude product was purified by flash
chromatography on silica gel (eluent: AcOEt) to give the title
compound as an off-white solid. Yield = 2.56 g, 12.8 mmol, 61%.
1H NMR (400 MHz, CD2Cl2, 25°C, TMS): δ=7.89 (d,
3J(H,H)=6 Hz, 1H), 6.64 (d, 4J(H,H)=2.5 Hz, 1H), 6.46 (dd,
3J(H,H)=6 Hz; 4J(H,H)=2.5 Hz, 1H), 2.97 ppm (s, 6H).
dimethylamino)pyridine gold (III) (a)
To a round bottom flask, I (200 mg, 0.4 mmol) dissolved in
CH2Cl2 and sodium tetrachloroaurate (III) dihydrate (200 mg,
0.5 mmol) dissolved in CH3CN were added. The reaction mixture
was stirred for 24 h at r.t. The colorless precipitate that formed
was filtered off and washed with hexane giving the title
compound. The product was used without further purification,
estimated purity by 1H NMR > 95%. Yield = 195 mg, 0.36 mmol,
61%. 1H NMR (400 MHz, CD2Cl2, 25°C, TMS): δ=8.98 (d,
3J(H,H)=7.5 Hz, 1H), 8.11 (m, 1H), 7.71 (m, 1H), 7.50 (m, 1H),
6.89 (d, 4J(H,H)=3.1 Hz, 1H), 6.51 (dd, 3J(H,H)=7.5 Hz;
4J(H,H)=3.1 Hz, 1H), 3.26 ppm (s, 6H); 19F NMR (376 MHz,
CD2Cl2, 25 °C, CFCl3): δ=-62.97 ppm (s, 3F).
2-(3-trifluoromethylphenyl)-4-(N,N-dimethylamino)pyridine-
bis(pentafluorophenyl) gold (III) (1)
In a two-necked round bottom flask, iodopentafluorobenzene
(0.03 mL, 0.23 mmol) was added to dry Et2O (15 mL). To this
reaction mixture cooled to –80°C, 1.6 M nBuLi (0.14 mL, 0.224
mmol) was added and after 10 min., a (50.0 mg, 0.09 mmol) was
added. The reaction mixture was allowed to come to r.t. and the
residual solvent was removed via N2-flow. Crude product 1 was
purified by flash chromatography on silica (eluent:
CH2Cl2/hexane 1:1), to afford the pure title compound. Yield =
2-(3-trifluoromethylphenyl)-4-(N,N-dimethylamino)pyridine
(A)
To a Young Schlenk flask, 2-bromo-4-(N,N-dimethylamino)-
pyridine (1.00 g, 4.97 mmol), 3-trifluoromethylphenyl)boronic
acid (1.13 g, 5.97 mmol) and NaOH pellets (477 mg, 12.0 mmol)
were added. To this reaction mixture, H2O (15 mL) and dioxane
(25 mL) were added. After degassing the reaction mixture,
Pd(PPh3)4 dissolved in THF (approx. 7 mL) was added to the
reaction mixture, which was then heated to 100°C for 16 h. After
the reaction mixture was allowed to cool to room temperature,
the aqueous phase was extracted with CH2Cl2 and the organic
phases were washed with H2O. Drying of the combined organic
phases with MgSO4 and evaporation of the solvent in vacuo
delivered the crude product. The crude product was further
purified by flash chromatography on silica gel (eluent:
CH2Cl2/AcOEt 1:1) to afford the title compound as an off-white
solid. Yield = 770 mg, 2.89 mmol, 58%. 1H NMR (400 MHz,
CD2Cl2, 25°C, TMS): δ=8.29 (d, 3J(H,H)=5.6 Hz, 1H), 8.27 (m,
1
39.0 mg, 0.055 mmol, 52%. H NMR (500 MHz, CD2Cl2, 25°C,
TMS): δ=7.96 (m, 1H), 7.73 (d, 3J(H,H)=7.0 Hz, 1H), 7.46 (m,
4
3
1H), 7.06 (d, J(H,H)=2.9 Hz, 1H), 6.99 (d, J(H,H)=7.9 Hz, 1H),
6.43 (dd, 3J(H,H)=7.1 Hz; 4J(H,H)=2.9 Hz, 1H), 3.22 ppm (s, 6H);
13C NMR (125.78 MHz, CD2Cl2, 25°C, TMS): δ=164.1 (s), 161.5
(s), 156.6 (s), 148.8 (s), 147.9–147.6 (m), 147.5 (s), 146.2–
145.8 (m), 144.3–144.0 (m), 140.9–140.6 (m), 139.5–138.6 (m),
137.5–137.0 (m), 134.6 (s), 129.8 (q, 2J(C,C)=32.5 Hz; CCF3),
3
127.8 (s), 127.4 (q, J(C,C)=3.6 Hz; CCCF3), 126.9–126.1 (m),
124.6 (q, 1J(C,F)=272.2 Hz; CF3), 121.3 (s), 121.0 (q,
3J(C,C)=3.6 Hz; CCCF3), 109.1–108.5 (m), 106.9 (s), 102.3 (s),
40.1 ppm (s; N(CH3)2); 19F NMR (376 MHz, CD2Cl2, 25°C,
CFCl3): δ=-62.93 (s, 3F) -121.25 (m, 2F), -121.53 (m, 2F), -
158.07 (m, 2F), -158.70 (m, 2F), -161.55 (m, 1F), -162.16 ppm
(m, 1F); Elemental analysis (%) calcd for: C26H12N2AuF13: C,
39.22; H, 1.52; N, 3.52; Found: C, 39.22; H, 1.52; N, 3.52.
3
4
1H), 8.18 (dd, J(H,H)=7.7 Hz; J(H,H)=1.1 Hz, 1H), 7.65 (m, 1
H), 7.58 (m, 1H), 6.96 (d, 4J(H,H)=2.5 Hz, 1H), 6.54 (dd,
3J(H,H)=5.9 Hz; 4J(H,H)=2.6 Hz, 1H), 3.07 ppm (s, 6H); 19F NMR
(376 MHz, CD2Cl2, 25°C, CFCl3): δ=- 62.81 ppm (s, 3F).
2-(3-trifluoromethylphenyl)-4-(N,N-dimethylamino)pyridine-
Chloro-2-(3-trifluoromethylphenyl)-4-(N,N-dimethylamino)-
pyridine mercury (II) (I)
bis-4-fluorophenyl acetylene (2)
To
a
flask containing dry Et2O (10 mL), 1-ethynyl-4-
To a Young Schlenk, EtOH (25 mL) and AcOH (0.4 mL) were
added to a mixture of A (400 mg, 1.5 mmol) and Hg(OAc)2 (478
mg, 1.5 mmol). The reaction mixture was then heated at 85°C
for 48 h. After 48 h, the reaction mixture was allowed to cool to
r.t. Concentrated LiCl in EtOH was added dropwise to the
fluorobenzene (0.052 mL, 0.45 mmol) was added and the
reaction mixture was cooled to –80°C. To the reaction mixture,
2.5 M nBuLi (0.18 mL 0.45mmol) was carefully added leading to
a slightly yellowish solution. After stirring the reaction mixture at
this temperature for 10 min., a (100 mg, 0.188 mmol) was added
which led to a color change from yellow to brown. After 1 h, the
solvent was removed by a stream of N2. Crude product 2 was
purified by flash chromatography on silica gel (eluent:
CH2Cl2/hexane 1:1), to afford the pure title compound 2. Yield =
81.3 mg, 0.116 mmol, 62%. 1H NMR (400 MHz, CD2Cl2, 25°C,
TMS): δ=9.08 (m, 1H), 8.38 (m, 1H), 7.88 (s, 1H), 7.60 (m, 1H),
7.52 (m, 4H), 7.04 (m, 4H), 6.97 (m, 1H), 6.57 (m, 1H), 3.22 ppm
reaction mixture resulting in
a colorless precipitate. The
precipitate was filtered off and washed with hexane giving the
title compound as an off-white solid. The crude product was
used without further purification. Yield = 205 mg, 0.41 mmol,
27.3%.
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
(s, 6H); 13C NMR (125.78 MHz, CD2Cl2, 25°C, TMS): δ=164.2 (s), (m, 1H), 6.52 (m, 1H), 3.23 ppm (s, 6H); 19F NMR (376 MHz,
163.3 (s), 163.1 (s), 161.3 (s), 161.1 (s), 159.5 (s), 156.4 (s)
149.9 (s), 147.4 (s), 136.3 (s), 133.9–133.7 (m), 129.3 (q,
2J(C,C)=32.3 Hz, CCF3), 128.5 (s), 127.6–127.5 (m), 127.1 (s),
124.7 (q, 1J(C,F)=272.2 Hz; CF3), 122.5–122.4 (m), 120.5 (s),
115.7–155.4 (m), 114.7 (s), 106.7 (s), 102.6 (s), 101.9 (s), 98.1
(s) 40.2 ppm (s; N(CH3)2); 19F NMR (376 MHz, CD2Cl2, 25°C,
CFCl3): δ=-62.80 (s, 3F) -113.58 (s, 1F), -113.97 ppm (s, 1F);
Elemental analysis (%) calcd for: C30H20N2AuF5: C, 51.44; H,
2.88; N, 4.00; Found: C, 51.14; H, 2.71; N, 3.85.
CD2Cl2, 25°C, CFCl3): δ=-57.93 ppm (s, 3F).
(2-(4-trifluoromethoxyphenyl))-4-(N,N-
dimethylamino)pyridine)bis(pentafluorophenyl) gold(III) (3)
To
a
round bottom flask with dry Et2O (10 mL),
iodopentafluorobenzene (0.05 mL, 0.44 mmol) was added and
the reaction mixture was cooled to –80°C. After 5 min., 2.5 M
nBuLi (0.13 mL, 0.325 mmol) was carefully added to the reaction
mixture and a change in color to yellow was observed. After
another 5 min., III (74.1 mg, 0.14 mmol) was added to the
reaction mixture and stirred for 10 min. The solvent was
evaporated in vacuo and the crude product was purified by flash
chromatography on silica gel (eluent: CH2Cl2/hexane 1:1), to
afford the pure 3. Yield = 60.3 mg, 0.07 mmol, 53%. 1H NMR
(400 MHz, CD2Cl2, 25°C, TMS): δ=7.82 (d, 3J(H,H)=8.6 Hz, 1H),
7.70 (d, 4J(H,H)=7.0 Hz, 1H), 7.20 (m, 1H), 6.97 (d,
3J(H,H)=2.9 Hz, 1H), 6.67 (s, 1H), 6.41 (dd, 4J(H,H)=7.1 Hz;
3J(H,H)=2.9 Hz, 1H), 3.19 ppm (s, 6H); 13C NMR (100.53 MHz,
CD2Cl2, 25°C, TMS): δ=164.2 (s), 156.5 (s), 150.7 (s), 148.7 (s),
145.6 (s), 145.2 (s), 125.9 (s), 125.8 (s), 119.5 (s), 106.6 (s),
102.7 (s), 40.0 ppm (s; N(CH3)2); 19F NMR (376 MHz, CD2Cl2,
25°C, CFCl3): δ=-57.98 (s, 3F), -121.23 (m, 2F), -121.57 (m, 2F),
-158.09 (m, 2F), -148.45 (m, 2F) -161.57 ppm (m, 1F), -162.16
2-(4-trifluoromethoxyphenyl)-4-(N,N-dimethylamino)pyridine
(B)
To a Schlenk flask with 2-bromo-4-(N,N-dimethylamino)pyridine
(802 mg, 3.98 mmol), 4-(trifluoromethoxy)-phenyl)boronic acid
(993 mg, 4.82 mmol) and NaOH (386 mg, 9.65 mmol), H2O (15
mL) and dioxane (25 mL) were added. The brownish reaction
mixture was then degassed for 35 min. before Pd(PPh3)4
dissolved in toluene (10 mL) was added. The reaction mixture
was stirred for 97 h at 100°C and was then cooled to r.t.
Extraction of the aqueous phase with CH2Cl2, drying the
combined organic phases over MgSO4 and evaporation of the
solvent in vacuo delivered the crude product B. Crude product B
was purified by flash chromatography on silica gel (eluent:
AcOEt/CH2Cl2 2:1), to afford the pure title compound. Yield =
(m,
1F);
Elemental
analysis
(%)
calcd
for:
1
301 mg, 1.07 mmol, 27%. H NMR (400 MHz, CD2Cl2, 25°C,
C33H11AuF15N·1/3C6H14: C, 39.99; H, 2.00; N, 3.45; Found: C,
39.82; H, 2.01; N, 2.98.
TMS): δ=8.25 (d, 3J(H,H)=6.0 Hz, 1H), 7.99 (m, 2H), 7.29 (m,
2H), 6.90 (d, 4J(H,H)=2.6 Hz, 1H), 6.51 (dd, 4J(H,H)=6.0 Hz;
3J(H,H)=2.6 Hz, 1H), 3.06 ppm (s, 6H); 19F NMR (376 MHz,
CD2Cl2, 25°C, CFCl3): δ=-58.15 ppm (s, 3F).
2-2,3,4-fluorophenyl-4-(N,N-dimethylamino)pyridine (C)
To
a
Young
Schlenk
flask,
2-bromo-4-(N,N-
dimethylamino)pyridine
(1.51
g, 7.51
mmol), (2,3,4-
Chloro-2-(4-trifluoromethoxyphenyl)-4-(N,N-
dimethylamino)pyridine mercury (II) (II)
trifluorophenyl)boronic acid (1.59 g, 9.01 mmol) and NaOH
pellets (754 mg, 18.9 mmol) were added. To this mixture, H2O
(15 mL) and dioxane (25 mL) were added. After degassing of
the reaction mixture, Pd(PPh3)4 dissolved in toluene (approx. 7
mL), was added. The reaction mixture was then heated to 100°C
for 16 h. The reaction mixture was then allowed to cool to room
temperature, and the aqueous phase was extracted with CH2Cl2.
Washing the organic phases with H2O, drying of the combined
organic phases with MgSO4 and evaporation of the solvent in
vacuo delivered the crude product. The crude product was
purified by flash chromatography on silica gel (eluent:
CH2Cl2/AcOEt 1:2) to afford the title compound. Yield = 244 mg,
0.97 mmol, 13%. 1H NMR (400 MHz, CD2Cl2, 25°C, TMS):
δ=8.27 (d, 3J(H,H)=6.0 Hz, 1H), 7.52 (m, 1H), 7.08 (m, 1H), 6.93
(m, 1H), 6.52 (dd, 3J(H,H)=6.0 Hz; 4J(H,H)=2.6 Hz, 1H),
3.04 ppm (s, 6H); 19F NMR (376 MHz, CD2Cl2, 25°C, CFCl3): δ=-
135.97 (m, 1F), -139.07 (m, 1F), -162.20 ppm (m, 1F).
In a Young Schlenk with c (300 mg, 1.06 mmol) and Hg(OAc)2
(339 mg, 1.06 mmol), EtOH (25 mL) and 0.4 mL AcOH were
added. The reaction mixture was heated at 85°C for 48 h. After,
the reaction mixture was allowed to cool to r.t., concentrated LiCl
in EtOH was added dropwise. The colorless precipitate that
ensued was filtered off and washed with hexane giving crude II.
The crude product was used further without purification. Yield =
150 mg, 0.29 mmol, 27%. 1H NMR (400 MHz, CD2Cl2, 25°C,
3
4
TMS): δ=8.18 (d, J(H,H)=6.0 Hz, 1H), 8.06 (d, J(H,H)=8.6 Hz,
4
1H), 7.45 (m, 1H), 7.23 (m, 1H), 7.07 (d, J(H,H)=1.5 Hz, 1 H),
6.60 (m, 1H) 3.10 ppm (s, 6H); 19F NMR (376 MHz, CD2Cl2,
25°C, CFCl3): δ=-58.00 ppm (s, 3F).
Bis(chloro)-2-(4-trifluoromethoxyphenyl)
4-(N,N-
dimethylamino)pyridine gold (III) (b). To a round bottom flask
with III (150 mg, 0.29 mmol) in CH2Cl2, sodium tetrachloroaurate
(III) dihydrate (133 mg, 0.33 mmol) dissolved in CH3CN was
added. The reaction mixture was stirred for 24 h at r.t. The
colorless precipitate that formed was filtered off and washed with
hexane giving b. The product was used without further
purification, estimated purity by 1H NMR > 95%. Yield = 105 mg,
0.19 mmol, 58%. 1H NMR (400 MHz, CD2Cl2, 25°C, TMS):
δ=9.05 (m, 1H), 7.92 (m, 1H), 7.62 (m, 1H), 7.26 (m, 1H), 6.83
Chloro-(2-2,3,4-fluorophenyl-4-(N,N-dimethylamino)pyridine)
mercury (II) (III)
To a Young Schlenk with C (320 mg, 1.27 mmol) and Hg(OAc)2
(403 mg, 1.27 mmol), EtOH (25 mL) and 0.4 mL AcOH were
added. The reaction mixture was heated at 85°C for 48 h. After
the reaction mixture was allowed to cool to r.t., concentrated LiCl
solution in EtOH was added dropwise to the reaction mixture.
The formed colorless precipitate was filtered off and washed
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
with hexane to crude pure III. The crude product was used
without further purification. Yield = 276 mg, 0.57 mmol, 45%.
states and unrestricted calculations for the the triplet states
without symmetry restriction. The final geometries were
confirmed to be potential energy minima by vibrational frequency
calculations at the same level of theory, as no imaginary
frequency was found. On the DFT optimized ground-state S0
geometries, TD-DFT calculations[19] were used to produce the
first 25 lowest singlet–singlet and the first 3 singlet–triplet
vertical excitations with the corresponding energies, transition
coefficients and oscillator strengths. The singly occupied
molecular orbitals were obtained by restricted open-shell single
point calculations on the optimized triplet state geometries. The
frontier orbital surfaces and spin density distributions reported
herein were generated by Gaussview[20] on Gaussian 09
formatted checkpoint output files with isovalues set to 0.02 and
0.004, respectively. The alkyne-containing compound 2 was
further investigated as we noticed that the character of the first
triplet excited state T1 varies with the rotation of the terminal
fluorobenzene ligands. The fully optimized structure of 2 was
called 2A and corresponds to an almost planar molecule. The
conformation with the fluorobenzene rings frozen perpendicular
to the cyclometalated ligand is denoted 2B. Several “in-between”
conformations characterized by fixed dihedral angle values of 15,
30, 45, 60 and 75° were also investigated.
Bis(chloro)-2-2,3,4-fluorophenyl-4-(N,N-
dimethylamino)pyridine gold (III) (c)
To a round bottom flask, III (276 mg, 0.57 mmol) dissolved in
CH2Cl2 and sodium tetrachloroaurate (III) dihydrate (258 mg,
0.65 mmol) dissolved in CH3CN were added. The reaction
mixture was stirred for 24 h at r.t. The formed colorless
precipitate was filtered off and washed with hexane to give c.
The product was used without further purification, estimated
1
1
purity by H NMR > 95%. Yield = 181 mg, 0.35 mmol, 54%. H
3
NMR (400 Hz, CD2Cl2, 25°C, TMS): δ=9.07 (d, J(H,H) =7.5 Hz,
1H), 7.82 (m, 1H), 7.24 (m, 1H), 6.54 (m, 1H), 3.22 ppm (s, 6H);
19F NMR (376 MHz, CD2Cl2, 25°C, CFCl3): δ=-128.43 (m, 1F), -
134.51 (m, 1F), -160.34 ppm (m, 1F).
2-2,3,4-fluorophenyl-4-(N,N-dimethylamino)pyridine-
bis(pentafluorophenyl) gold (III) (4)
To a two-necked round bottom flask with dry Et2O (15 mL),
iodopentafluorobenzene (0.05 mL, 0.37 mmol) was added. The
reaction mixture was cooled to –80°C and 2.5 M nBuLi (0.09 mL,
0.225 mmol) was added. After 10 min. of stirring, c (47.0 mg,
0.09 mmol) was added and a change in color to a greenish
solution was observed which further turned to a colorless
solution. The reaction was allowed to stir for 30 min. and after
X-ray crystallography
The single-crystal X-ray diffraction data was collected at 183(1)
the solvent was removed via N2-flow resulting in a crude product. K on an Agilent Technologies Xcalibur Ruby area-detector
This was further purified by flash chromatography on silica gel
(eluent: CH2Cl2/hexane 1:1), to afford pure 4. Yield = 27.3 mg,
0.035 mmol, 39%. 1H NMR (400 MHz, CD2Cl2, 25°C, TMS):
diffractometer using a single wavelength Enhance X-ray source
with Mo Ka radiation (l = 0.71073 Å)[21] from a micro-focus X-ray
source and an Oxford Instruments Cryojet XL cooler. The
selected suitable single crystal was mounted using polybutene
3
δ=7.69 (d, J(H,H)=7.0 Hz, 1H), 7.44 (m, 1H), 6.47 (m, 1H), 6.39
3
4
(dd, J(H,H)=7.0 Hz; J(H,H)=2.6 Hz, 1H), 3.18 ppm (s, 6H); 13C
NMR (125.78 MHz, CD2Cl2, 25°C, TMS): δ=161.8–161.7 (m),
156.6 (s), 152.9–152.8 (m), 151.9 (s), 151.1–151.0 (m), 150.9–
150.8 (m), 149.0–148.9 (m), 148.8 (s), 147.8–147.6 (m), 146.1–
145.7 (m), 144.2–144.0 (m), 141.0–140.7 (m), 140.0–138.7 (m),
137.5–137.0 (m), 131.1 (s), 125.6–124.6 (m), 117.4–117.3 (m),
108.9–108.3 (m), 106.1 (s), 106.0 (s), 34.0 ppm (s; N(CH3)2);
19F NMR (376 MHz, CD2Cl2, 25°C, CFCl3): δ=-121.40 (m, 1F), -
131.04 (m, 1F), -135.37 (m,1F), -157.73 (t, 2F), -158.09 (t, 2F), -
161.39 (m, 2F), -161.73 (m, 2F), -162.35 ppm (m, 2F);
Elemental analysis (%) calcd for: C25H11N2AuF13: C, 38.38; H,
1.29; N, 3.58; Found: C, 38.20; H, 1.23; N, 3.51.
oil on a flexible loop fixed on a goniometer head and
immediately transferred to the diffractometer. The pre-
experiment, data collection, data reduction and analytical
absorption correction[22] were performed with the program suite
CrysAlisPro.[23] Using Olex2,[24] the structure was solved with the
SHELXT[25] small molecule structure solution program and
refined with the SHELXL2014[26] program package by full-matrix
least-squares minimization on F2. PLATON[27] was used to check
the result of the X-ray analysis. For more details about the data
collection and refinements parameters, see the Supporting
Information and the Crystallographic Information file. CCDC-
1511251
(complex
4)
contains
the
supplementary
crystallographic data for this paper. The data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Computational details
The Gaussian 09 program package[14] was used for all density
functional theory (DFT) and time-dependent DFT (TD-DFT)
calculations reported in the manuscript. The properties of
compounds 1, 2, 3 and 4 were studied using the hybrid
functional PBE1PBE[15] associated with the Stuttgart/Dresden
effective core potentials (SDD) basis set[16] for the Au center
augmented with one f-polarization function (α = 1.050), with the
standard 6-31+G(d) basis set[17] for the remaining atoms, and
with the conductive polarizable continuum model (CPCM)[18] to
take the solvent effects into acount (dichloromethane). The
molecular structures of the ground states and lowest triplet
states were obtained by restricted calculations for the ground
Acknowledgements
The authors wish to thank Prof. Roger Alberto for the generous
support. Financial support from the Swiss National Science
Foundation (Grant no. 200020_156967) and the University of
Zurich is gratefully acknowledged.
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
156; d) L. Xiao, Z. Chen, B. Qu, J. Luo, S. Kong, Q. Gong and J. Kido, Adv.
Mater. 2011, 23, 926-952; e) H. Sasabe and J. Kido, J. Mater. Chem. C 2013,
1, 1699-1707; f) K. S. Yook and J. Y. Lee, Adv. Mater. 2012, 24, 3169-3190;
g) C. L. Mulder, K. Celebi, K. M. Milaninia and M. A. Baldo, Appl. Phys. Lett.
2007, 90, 211109; h) J. Lee, H.-F. Chen, T. Batagoda, C. Coburn, P. I.
Djurovich, M. E. Thompson and S. R. Forrest, Nat Mater 2016, 15, 92-98.
[10] A. J. Lees, Chem. Rev. 1987, 87, 711-743.
[11] a) D.-A. Rosca, D. A. Smith and M. Bochmann, Chem. Commun. 2012, 48,
7247-7249; b) A. S. K. Hashmi, C. Lothschütz, M. Ackermann, R. Doepp, S.
Anantharaman, B. Marchetti, H. Bertagnolli and F. Rominger, Eur. J. Chem.
2010, 16, 8012-8019.
[12] a) Q.-L. Xu, C.-C. Wang, T.-Y. Li, M.-Y. Teng, S. Zhang, Y.-M. Jing, X.
Yang, W.-N. Li, C. Lin, Y.-X. Zheng, J.-L. Zuo and X.-Z. You, Inorg. Chem.
2013, 52, 4916-4925; b) R. Uson, A. Laguna and J. Vicente, J. Organomet.
Chem. 1977, 131, 471-475; c) R. Usón, J. Vicente, J. A. Cirac and M. T.
Chicote, J. Organomet. Chem. 1980, 198, 105-112.
Keywords: Gold
• Phosphorescence • Blue • Fluorine •
Cyclometalated
[1] a) P.-T. Chou, Y. Chi, M.-W. Chung and C.-C. Lin, Coord. Chem. Rev.
2011, 255, 2653-2665; b) P. T. Chou and Y. Chi, Eur. J. Chem. 2007, 13, 380-
395; c) M. A. Baldo, D. F. O'Brien, Y. You, A. Shoustikov, S. Sibley, M. E.
Thompson and S. R. Forrest, Nature 1998, 395, 151-154; d) S. Kappaun, C.
Slugovc and E. J. W. List, Int. J. Mol. Sci. 2008, 9, 1527-1547; e) M. K.
Nazeeruddin and M. Grätzel, Structure and Bonding 2007, 123, 113-175; f) R.
Visbal, J. M. Lopez-de-Luzuriaga, A. Laguna and M. C. Gimeno, Dalton Trans.
2014, 43, 328-334; g) M. Bardají, A. Laguna, V. M. Orera and M. D.
Villacampa, Inorg. Chem. 1998, 37, 5125-5130; h) L. Huang, M. Rudolph, F.
Rominger and A. S. K. Hashmi, Angew. Chem. Int. Ed. 2016, 55, 4808-4813; i)
L. Huang, F. Rominger, M. Rudolph and A. S. K. Hashmi, Chem. Commun.
2016, 52, 6435-6438.
[13] E. Baranoff and B. F. E. Curchod, Dalton Trans. 2015, 44, 8318-8329.
[14] G. W. T. M. J. Frisch, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R.
Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H.
Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G.
Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J.
Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.
A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E.
Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K.
Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N.
Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J.
Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi,
C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A.
Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J.
B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox. in Gaussian 09, Vol.
Gaussian, ing., Wallingford CT, 2013, p. Gaussian 09.
[15] C. Adamo and V. Barone, J. Chem. Phys. 1999, 110, 6158-6170.
[16] T. H. H. Jr Dunning, P.; Plenum: New York, , Mod. Theor. Chem. 1976, 3.
[17] R. Ditchfield, W. J. Hehre and J. A. Pople, J. Chem. Phys. 1971, 54, 724-
728.
[18] a) V. Barone and M. Cossi, J. Phys. Chem. A 1998, 102, 1995-2001; b) M.
R. Cossi, N.; Scalmani, G.; Barone, V. , J. Comput. Chem. 2003, 24, 669.
[19] a) R. Bauernschmitt and R. Ahlrichs, Chem. Phys. Lett. 1996, 256, 454-
464; b) M. E. Casida, C. Jamorski, K. C. Casida and D. R. Salahub, J. Chem.
Phys. 1998, 108, 4439-4449; c) R. E. Stratmann, G. E. Scuseria and M. J.
Frisch, J. Chem. Phys. 1998, 109, 8218-8224.
[2] a) K. M.-C. Wong, L.-L. Hung, W. H. Lam, N. Zhu and V. W.-W. Yam, J.
Am. Chem. Soc. 2007, 129, 11662-11662; b) C.-W. Chan, W.-T. Wong and
C.-M. Che, Inorg. Chem. 1994, 33, 1266-1272.
[3] a) L. Gao, D. V. Partyka, J. B. Updegraff, N. Deligonul and T. G. Gray, Eur.
J. Inorg. Chem. 2009, 2009, 2711-2719; b) M. Vijayakumar and M. S.
Gopinathan, J. Mol. Struct.: THEOCHEM. 1996, 361, 15-19.
[4] a) W.-P. To, K. T. Chan, G. S. M. Tong, C. Ma, W.-M. Kwok, X. Guan, K.-H.
Low and C.-M. Che, Angew. Chem. Int. Ed. 2013, 52, 6648-6652; b) W.-P. To,
G. S.-M. Tong, W. Lu, C. Ma, J. Liu, A. L.-F. Chow and C.-M. Che, Angew.
Chem. Int. Ed. 2012, 51, 2654-2657; c) J. J. Yan, A. L.-F. Chow, C.-H. Leung,
R. W.-Y. Sun, D.-L. Ma and C.-M. Che, Chem. Commun. 2010, 46, 3893-3895.
[5] a) V. W.-W. Yam, S. W.-K. Choi, T.-F. Lai and W.-K. Lee, J. Chem. Soc.,
Dalton Trans. 1993, 1001-1002; b) V. W.-W. Yam, T.-F. Lai and C.-M. Che, J.
Chem. Soc., Dalton Trans. 1990, 3747-3752.
[6] a) V. K.-M. Au, K. M.-C. Wong, N. Zhu and V. W.-W. Yam, J. Am. Chem.
Soc. 2009, 131, 9076-9085; b) K. M.-C. Wong, X. Zhu, L.-L. Hung, N. Zhu, V.
W.-W. Yam and H.-S. Kwok, Chem. Commun. 2005, 2906-2908; c) V. K.-M.
Au, K. M.-C. Wong, N. Zhu and V. W.-W. Yam, Eur. J. Chem. 2011, 17, 130-
142; d) V. W.-W. Yam and E. C.-C. Cheng, Chem. Soc. Rev. 2008, 37, 1806-
1813; e) V. K.-M. Au, K. M.-C. Wong, D. P.-K. Tsang, M.-Y. Chan, N. Zhu and
V. W.-W. Yam, J. Am. Chem. Soc. 2010, 132, 14273-14278; f) V. K.-M. Au, W.
H. Lam, W.-T. Wong and V. W.-W. Yam, Inorg. Chem. 2012, 51, 7537-7545.
[7] a) A. Herbst, C. Bronner, P. Dechambenoit and O. S. Wenger,
Organometallics 2013, 32, 1807-1814; b) P. I. da S. Maia, H. H. Nguyen, D.
Ponader, A. Hagenbach, S. Bergemann, R. Gust, V. M. Deflon and U. Abram,
Inorg. Chem. 2012, 51, 1604-1613; c) C. Nevado and R. Kumar, Angew.
Chem. Int. Ed. 2016, DOI: 10.1002/anie.201607225; d) J. Fernandez-Cestau,
B. Bertrand, M. Blaya, G. A. Jones, T. J. Penfold and M. Bochmann, Chem.
Commun. 2015, 51, 16629-16632.
[20] V. GaussView, Dennington, R.; Keith, T.; Millam, J. Semichem Inc.,
Shawnee Mission, KS, 2009.
[21] T. Rigaku Oxford Diffraction (formerly Agilent Technologies). Rigaku
Corporation, Japan.
[22] R. C. Clark and J. S. Reid, Acta Crystallogr., Sect. A 1995, 51, 887-897.
[23] V. R. C. Rigaku Oxford Diffraction. CrysAlisPro, Tokyo, Japan.
[24] O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and H.
Puschmann, J. Appl. Crystallogr. 2009, 42, 339-341.
[8] a) J. A. Garg, O. Blacque, T. Fox and K. Venkatesan, Inorg. Chem. 2010,
49, 11463-11472; b) J. A. Garg, O. Blacque and K. Venkatesan, Inorg. Chem.
2011, 50, 5430-5441; c) A. Szentkuti, M. Bachmann, J. A. Garg, O. Blacque
and K. Venkatesan, Eur. J. Chem. 2014, 20, 2585-2596; d) M. Bachmann, O.
Blacque and K. Venkatesan, Dalton Trans. 2015, 44, 10003-10013; e) A.
Szentkuti, J. A. Garg, O. Blacque and K. Venkatesan, Inorg. Chem. 2015, 54,
10748-10760.
[25] G. Sheldrick, Acta Crystallogr., Sect. A 2015, 71, 3-8.
[26] G. Sheldrick, Acta Crystallogr., Sect. C 2015, 71, 3-8.
[27] A. Spek, Acta Crystallogr., Sect. D 2009, 65, 148-155.
[9] a) Y. L. Chang and Z. H. Lu, J. Disp. Technol. 2013, 9, 459-468; b) H. Fu,
Y.-M. Cheng, P.-T. Chou and Y. Chi, Mater. Today 2011, 14, 472-479; c) G.
Zhou, W.-Y. Wong and S. Suo, J. Photochem. Photobiol., C 2010, 11, 133-
This article is protected by copyright. All rights reserved.

10.1002/chem.201605567
Chemistry - A European Journal
FULL PAPER
FULL PAPER
Blue emitting gold(III) complexes were
Michael Bachmann, Jasmin Terreni,
achieved
through
rational
Olivier Blacque, and Koushik
Venkatesan*[a]
modifications of the phenylpyridine
ligand scaffold.
Page No. – Page No.
Rationally Designed Blue Triplet
Emitting Gold(III) Complexes Based
on
Phenylpyridine
Derived
Framework
This article is protected by copyright. All rights reserved.