In Situ Spectroelectrochemical Investigations of RuII Complexes with Bispyrazolyl Methane Triarylamine Ligands

Article abstract of DOI:10.1071/CH16555

The synthesis and characterization of two triarylamine ligands, 4-(di(1H-pyrazol-1-yl)methyl)-N-(4-(di(1H-pyrazol-1-yl)methyl)phenyl)-N-phenylaniline (TPA-2bpm) and tris(4-(di(1H-pyrazol-1-yl)methyl)phenyl)amine (TPA-3bpm), containing the bispyrazolylmeth

Full text of DOI:10.1071/CH16555

RESEARCH FRONT
CSIRO PUBLISHING
Aust. J. Chem.
Full Paper
http://dx.doi.org/10.1071/CH16555
In Situ Spectroelectrochemical Investigations
II
of Ru Complexes with Bispyrazolyl Methane
Triarylamine Ligands
A
B
C
C
Carol Hua, Brendan F. Abrahams, Floriana Tuna, David Collison,
,
A D
and Deanna M. D’Alessandro
A
School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia.
B
School of Chemistry, The University of Melbourne, Melbourne, Vic. 3010, Australia.
C
School of Chemistry, The University of Manchester, Manchester, M13 9PL, UK.
D
Corresponding author. Email: deanna.dalessandro@sydney.edu.au
The synthesis and characterization of two triarylamine ligands, 4-(di(1H-pyrazol-1-yl)methyl)-N-(4-(di(1H-pyrazol-1-yl)
methyl)phenyl)-N-phenylaniline (TPA-2bpm) and tris(4-(di(1H-pyrazol-1-yl)methyl)phenyl)amine (TPA-3bpm), con-
II
taining the bispyrazolylmethane moiety and its Ru terpyridine complexes are presented. The redox properties of the
II
ligands and Ru complexes are explored in detail through cyclic and square-wave voltammetry in addition to in situ UV-
vis-near infrared, electron paramagnetic resonance, and fluorescence spectroelectrochemistry. It was demonstrated that
the triarylamine radical cation was able to be generated, and further, TPA-2bpm underwent an electrochemically induced
dimerization process.
Manuscript received: 30 September 2016.
Manuscript accepted: 15 December 2016.
Published online: 1 February 2017.
Introduction
[23]
electronics,
[
cells.
photovoltaic devices, and dye-sensitized solar
24–26]
The development of materials for applications in optoelectronic
devices, dye-sensitized solar cells, and conductive materials is
particularly important in the pursuit of technologies for renew-
able resources. In this regard, ruthenium complexes based on
terpyridine and bipyridine ligands have received considerable
In the current work, we present the synthesis and characteri-
zation of two novel triarylamine bispyrazolyl methane ligands,
tris(4-(di(1H-pyrazol-1-yl)methyl)phenyl)amine (TPA-3bpm)
and 4-(di(1H-pyrazol-1-yl)methyl)-N-(4-(di(1H-pyrazol-1-yl)
methyl)phenyl)-N-phenylaniline (TPA-2bpm), and their result-
[
1]
attention in several areas including water oxidation, solar light
[6,7]
[
2–5]
II
to energy conversion,
[
optoelectronic applications,
The family of coordination compounds derived
and
ing Ru terpyridine complexes. The redox properties of the
II
ligands and Ru complexes are examined in detail through
8,9]
catalysis.
0
II
from 2,2 -bipyridine (bpy), [Ru (bpy) ] , has been widely
2þ
cyclic and square-wave voltammetries in addition to in situ
UV-vis-near infrared, electron paramagnetic resonance (EPR),
and fluorescence spectroelectrochemistry. The presence of
an electrochemically induced dimerization process of the
TPA-2bpm ligand is also discussed.
3
studied for their charge-transfer properties from excited elec-
tronic states, which have applications in solar cells for the
conversion of visible radiation into chemical energy.
Several Ru complexes with triarylamine-based ligands
have been developed for applications in optoelectronic devices,
II
[
10,11]
dye-sensitized solar cells,
and conductive materials.
Results and Discussion
A common motif is the use of either a bipyridine or terpyridine
co-ligand in conjunction with a triarylamine-containing
Synthesis and Characterization
[
10,12]
ligand.
Triarylamines undergo a one-electron oxidation
The ligands 4-(di(1H-pyrazol-1-yl)methyl)-N-(4-(di(1H-pyr-
azol-1-yl)methyl)phenyl)-N-phenylaniline (TPA-2bpm) and
tris(4-(di(1H-pyrazol-1-yl)methyl)phenyl)amine (TPA-3bpm)
were synthesized via a two-step reaction (Scheme 1) involving
formylation of triphenylamine followed by a cobalt condensa-
tion with pyrazole to yield TPA-2bpm as a cream solid (68 %
yield) and TPA-3bpm as a pale yellow solid (65 % yield).
Colourless block crystals of TPA-2bpm and TPA-3bpm were
obtained on slow evaporation of solvent from a solution of
the ligand in chloroform (TPA-2bpm) or vapour diffusion of
pentane into a solution of the ligand in dichloromethane
(TPA-3bpm). The structure of TPA-2bpm was solved and
either by chemical or electrochemical means to form their
radical cation state. When two or more triarylamines are
covalently linked via a bridge facilitating electronic coupling,
[13–19]
mixed-valence systems result.
The redox centres are
transformed into different formal oxidation states by the removal
of an electron, creating a ‘hole’ in the system, which may be
localized on one of the redox centres, or if the two redox centres
are strongly coupled, may be symmetrically delocalized onto
[
19–22]
several sites.
Mixed-valence compounds, in addition
to being valuable systems for the understanding of electron
transfer, have significant potential for use in molecular
Journal compilation � CSIRO 2017
www.publish.csiro.au/journals/ajc

B
C. Hua et al.
N
N
N
N
OHC
CHO
N
N
i) Imidazole,
Trifluoroacetic
i) Pyrazole, NaH
N
N
ii) SOCl2
iii) COCl2
N
N
anhydride/CH CN
3
N
R
ii) HCl (2 M)/CH CN
THF
3
R
R ϭ H or CHO
R ϭ H (TPA-2bpm)
ϭ PzCHPz (TPA-3bpm)
(PF6)3
N
N
Cl
N
N
N
N
i.Ru(tpy)Cl3
NMM
MeOH
N
N
Ru
N
N
N
N
N
Ru
N
N
N
N
N
N
N
N
N
Cl
N
R
ii.NH PF /H O
4
6
2
N
R
R ϭ H (TPA-2bpm)
ϭ PzCHPz (TPA-3bpm)
R ϭ H
ϭ Ru(tpy)ClPzCHPz
II
Scheme1. Synthesisof TPA-2bpmandTPA-3bpmligands(top),andRu terpyridinecomplexes(bottom). CH
3
CN¼ acetonitrile;THF ¼ tetrahydrofuran;
tpy ¼ 2,6-bis(2-pyridyl)pyridine, more commonly referred to as terpyridine; NMM ¼ N-methylmorphine; MeOH ¼ methanol.
(a)
(b)
Fig. 1. Crystal structure of the (a) TPA-2bpm ligand showing the asymmetric unit; and (b) TPA-3bpm ligand (only a
single component of the disordered structure is shown) at 50 % thermal ellipsoids where the hydrogens have been
omitted for clarity; C, grey; N, blue; O, red.
refined in the triclinic space group P-1. The asymmetric unit
consisted of one ligand unit where the nitrogen binding sites in
the bispyrazolylmethane (bpm) moiety point away from each
other (Fig. 1a). The large thermal ellipsoids of the atoms of the
pyrazole rings suggest rotational movement of the ring about the
methine linkage that joins the two pyrazole rings. The crystal
structure of TPA-3bpm was solved and refined in the hexagonal
product, [RuCl(tpy)(TPA-2bpm)]PF , was obtained in 6 %
6
1
yield. The H NMR spectrum of [Ru Cl (tpy) (TPA-2bpm)]
2
2
2
(PF ) clearly displayed the presence of both the terpyridine and
6
2
TPA-2bpm ligands. A loss of symmetry of the terpyridine ligand
with unique resonances for each proton in the ligand was
observed due to the asymmetric environment about the Ru
centre. Assignments for each of the proton resonances were
1
1
space group P6 /m where the asymmetric unit consisted of one
3
achieved with the aid of a 2D H– H COSY (correlation
spectroscopy) NMR experiment.
sixth of a TPA-3bpm ligand with an associated water molecule
(Fig. 1b). The pyrazole and phenyl rings are both disordered
over two positions.
Ruthenium complexes with the TPA-2bpm and TPA-3bpm
ligands were synthesized by heating the ligand with Ru(tpy)Cl3
In the synthesis of the ruthenium complexes with TPA-
3bpm, three different species, the mono-, di-, and trisubstituted
dark purple ruthenium complexes, were obtained after column
chromatography (Supplementary Material). When a reaction
time of 20 h was used, the disubstituted species [Ru Cl (t-
(
tpy ¼ 2,6-bis(2-pyridyl)pyridine, more commonly referred to
2
2
as terpyridine) and N-methylmorphine (NMM) in dry methanol
at reflux. After ion exchange with KPF , dark purple solids were
py) (TPA-3bpm)](PF ) was obtained in 45 % yield and the
2 6 2
trisubstituted species [Ru Cl (tpy) (TPA-3bpm)](PF ) in 47 %
3 3 3 6 3
6
isolated and purified by column chromatography. When the
TPA-2bpm ligand was used, [Ru Cl (tpy) (TPA-2bpm)](PF )
was isolated in 26 % yield while the dark purple monosubstituted
yield with a small quantity (,5 %) of the monosubstituted
[RuCl(tpy)(TPA-3bpm)]PF species. A larger quantity of the
[RuCl(tpy)(TPA-3bpm)]PF complex could be obtained with a
6
2
2
2
6 2
6

Electrochemically Dimerized Ruthenium Complexes
C
(
a) 10
(b)
4
2
5
0
0
Ϫ2
Ϫ4
Ϫ6
Ϫ8
Ϫ10
Ϫ12
Ϫ5
Ϫ10
Ϫ15
Ϫ20
Ϫ25
Ϫ1
Ϫ1
Ϫ1
Ϫ1
Ϫ1
Ϫ1
1
2
5
00 mV s
00 mV s
00 mV s
100 mV s
200 mV s
500 mV s
Ϫ1
Ϫ1
1000 mV s
1000 mV s
Ϫ0.5
0
0.5
1.0
1.5
Ϫ0.5
0
0.5
1.0
1.5
Potential vs Fc/Fcϩ [V]
Potential vs Fc/Fcϩ [V]
(c) 15
(d)
25
20
15
10
5
0
1
0
5
0
Ϫ5
Ϫ10
Ϫ15
Ϫ20
Ϫ25
Ϫ30
Ϫ35
Ϫ40
Ϫ5
Ϫ10
Ϫ15
Ϫ20
Ϫ1
Ϫ1
1
2
5
1
00 mV s
100 mV s
200 mV s
500 mV s
Ϫ1
Ϫ1
Ϫ1
Ϫ1
00 mV s
Ϫ1
00 mV s
Ϫ1
000 mV s
1000 mV s
Ϫ2
Ϫ1
0
1
2
Ϫ2
Ϫ1
0
1
Potential vs Fc/Fcϩ [V]
Potential vs Fc/Fcϩ [V]
Fig. 2. Cyclic voltammograms of (a) TPA-2bpm; (b) TPA-3bpm; (c) [Ru
2
Cl
2
(tpy)
2
(TPA-2bpm)](PF
þ
6
)
2
; and (d) [RuCl(tpy)(TPA-3bpm)]PF at scan rates of
6
ꢀ1
1
00–1000 mV s in [(n-C
4
H
9
)
4
N]PF
6
/CH
3
CN electrolyte referenced against the Fc/Fc couple where the solid arrow indicates the direction of the forward
scan. The dashed arrow at ,0.6 V in (c) indicates the peak in the reverse cycle that is indicative of an electrochemical–chemical (EC) process.
1
shorter reaction time of 4 h. The H NMR spectrum of the
performing multiple cycling experiments in [(n-C H ) N]PF /
4 9 4 6
[
Ru Cl (tpy) (TPA-3bpm)](PF ) complex was complicated,
6 3
CH Cl owing to dimerization through the para position of the
2 2
3
3
3
with the symmetry of the complex being split around the
terpyridine resonances, resulting in different chemical shifts
for the three terpyridine groups coordinated to the three rutheni-
um centres, in addition to the chemically distinct environments
for the ligand resonances. The correct mass at m/z 597.47
corresponding to the triply charged [M – 3PF6] ion (calculated
m/z 597.73) was observed by electrospray ionisation mass
spectrometry (ESI-MS), confirming the formation of the ruthe-
nium complex.
TPA-2bpm ligand, which is a well-known phenomenon for
[
27,28]
triarylamines (see Supplementary Material).
The presence
of an electrochemical–chemical (EC) process was supported by
the irreversibility of the oxidative process for TPA-2bpm at low
ꢀ
1
scan rates (10–50 mV s ), but increasing reversibility at fast
3
þ
ꢀ1
scan rates (100–1000 mV s ) when there is insufficient time for
dimerization to occur (Fig. 2 and Supplementary Material). The
dimerization of the ligand was accelerated in less polar solvents
such as dichloromethane, where the cyclic voltammogram over
ꢀ1
the range of scan rates from 100 to 1000 mV s displayed a
more irreversible process than in acetonitrile, which is in
accordance with previously reported trends (Supplementary
Redox Properties
The redox properties of TPA-2bpm and TPA-3bpm were
investigated using cyclic voltammetry experiments in
[29]
Material).
As expected, TPA-3bpm showed no evidence
[
(n-C H ) N]PF /CH CN and [(n-C H ) N]PF /CH Cl elec-
2
for dimerization, with the peak due to formation of the triar-
ylamine radical cation remaining reversible over a range of scan
rates and electrolytes (Supplementary Material).
4
9 4
6
3
4
9 4
6
2
ꢀ
1
trolytes at scan rates of 10–1000 mV s (Fig. 2 and Supple-
mentary Material). One quasi-reversible peak was observed for
TPA-2bpm and TPA-3bpm at ,0.6 V versus ferrocene (Fc)/Fc
in both electrolytes, which was attributed to the one-electron
oxidation of the triarylamine core to its radical cation.
The peak at ,0.6 V for TPA-2bpm became increasingly
irreversible and exhibited a shift to higher potentials on
þ
Two main anodic processes were observed for all ruthenium
þ
complexes, where the reversible process at ,0.4 V versus Fc/Fc
II
III
was assigned tothe one-electronoxidation ofRu toRu (Fig. 2c,
d, Supplementary Material); the quasi-reversible second process
þ
at ,0.9 V versus Fc/Fc was due to the one-electron oxidation of

D
C. Hua et al.
ꢀ
1
the triarylamine to its radical cation state. Several irreversible
processes occur in the cathodic region due to reduction of the
terpyridine ligand.
while the band at 32800 cm decreased (Fig. 3). The bands
ꢀ
1
appearing at 14300 and 28100 cm can be assigned to oxida-
tion of the triarylamine core to its radical cation state and are
consistent with previously reported triarylamine systems.
[
14,30]
In the cyclic voltammogram of [Ru Cl (tpy) (TPA-2bpm)]
2
2
2
ꢀ1
(
PF ) , a second peak was observed on the reverse cycle at
6
0.6 V versus Fc/Fc , which suggested that an EC process was
The bands at 7600 and 20600 cm indicate dimerization of the
ligand at the unsubstituted para position, where the appearance
of the band in the NIR region was indicative of the formation of a
mixed-valence state and associated intervalence charge-transfer
process. The dimerization of triarylamines with unsubstituted
para positions on oxidation has been proposed to proceed owing
to the coupling of two molecules containing radical species
located on the para position of the phenyl ring (see Supple-
The dimerization leads to a short
distance (9.9 A) between adjacent triarylamine cores, allowing
electronic communication to occur via a low-energy electron-
transfer pathway. As the potential applied to TPA-2bpm was
increased from 1.0 to 1.2 V, the adjacent triarylamine core was
oxidized to its radical cation, leading to a decrease in the
2
þ
,
occurring during the forward sweep (Fig. 2c). The irreversible
EC process became increasingly prominent at fast scan rates of
5
ꢀ1
00 and 1000 mV s and may be attributed to dimerization of
TPA-2bpm as observed in the electrochemical and spectro-
electrochemical experiments (see above) for the ligand.
II
Electrochemical experiments on the Ru -containing TPA-
bpm complexes displayed more complex behaviour than those
[
15,28,29]
3
mentary Material).
˚
containing TPA-2bpm with regards to the oxidation of the
triarylamine core (Fig. 2d, Supplementary Material). In [RuCl
[14]
(
tpy)(TPA-3bpm)]PF , the additional process at ,0.75 V versus
6
þ
Fc/Fc may indicate electronic communication between the
III
oxidized Ru centre and the triarylamine core. As expected, the
ꢀ1
complexes containing TPA-3bpm were highly stable on elec-
þ
intensity of the NIR band at 7600 cm .
The solution-state spectroelectrochemical experiment for
TPA-3bpm in [(n-C H ) N]PF /CH CN electrolyte was char-
3
trochemical cycling between ꢀ0.6 and 1.75 V versus Fc/Fc at
ꢀ1
1
00 mV s (see Supplementary Material).
4
9 4
6
ꢀ1
acterized by the formation of bands at 14400 and 27500 cm
ꢀ1
and a decrease in the band at 32300 cm , which can be
attributed to the one-electron oxidation of the triarylamine core
to its corresponding radical cation state (see Supplementary
Material). Bands at 7600 and 20600 cm (as observed for TPA-
2bpm) were not formed as all para positions on the triarylamine
UV-Vis-Near IR Spectroelectrochemistry
A UV-vis-NIR spectroelectrochemical experiment on TPA-
ꢀ1
2
2
bpm revealed four new bands at 7600, 14300, 20600, and
8100 cm on application of a positive potential (of 0.9 V),
ꢀ1
(a) 60000
(b) 60000
0
to 0.75 V
0.95 to 1.15 V
5
0000
50000
40000
30000
20000
10000
0
40000
30000
20000
10000
0
5000
10000 15000 20000 25000 30000 35000
5000 10000 15000 20000 25000 30000 35000
Wavenumber [cmϪ1
]
Wavenumber [cmϪ1
]
(
c) 60000
(d)
6
5
4
3
2
1
0000
1.0 to 0.9 V
0.9 to 0.7 V
50000
40000
30000
20000
10000
0
0000
0000
0000
0000
0000
0
5000
10000 15000 20000 25000 30000 35000
5000
10000 15000 20000 25000 30000 35000
Wavenumber [cmϪ1
]
Wavenumber [cmϪ1
]
Fig. 3. Solution state UV-vis-NIR spectroelectrochemistry of [Ru
2 2 2 6 2 4 9 4 6 3
Cl (tpy) (TPA-2bpm)](PF ) in [(n-C H ) N]PF /CH CN electrolyte where the potential
was increased from (a) 0 to 0.75 V; (b) 0.95 to 1.15 V; and decreased from (c) 1.0 to 0.9 V; and (d) 0.9 to 0.7 V. The dashed lines represent the intermediate
spectra obtained over each potential range.

Electrochemically Dimerized Ruthenium Complexes
E
ligand are substituted in the TPA-3bpm ligand, precluding any
dimerization process.
All ruthenium complexes displayed similar spectral proper-
ties and trends in the spectral responses during oxidation. In the
neutral state, there are two main bands at ,20000 and
Comparison of the linewidth of the band at half height (Dn1/2)
of 3325 cm with the theoretical value calculated from the
ꢀ1
[
31,32]
ꢀ1
classical theory of Hush
(Dn1/28) of 4185 cm suggests
that the system is characteristic of a localized mixed-valence
compound. Further support can be found through comparison of
the electronic matrix coupling element, H , where 2H pro-
ꢀ
1
3
,
0000 cm (Fig. 3 and Supplementary Material). The band at
ab
ab
ꢀ
1
20000 cm was assigned to the d - p* metal-to-ligand
vides a measure of the difference between the lower and upper
potential energy surfaces (details of the calculation are provided
[21]
in the Supplementary Material). For TPA-2bpm, the value of
II
charge transfer (MLCT) transition from the Ru metal centre
ꢀ1
to the terpyridine ligand, while the band at 30000 cm was due
to the p - p* transitions of the aromatic systems present.
On application of a potential of 0.75 V to all ruthenium
complexes, the MLCT transition exhibited a blue shift from
ꢀ
1
ꢀ1
2Hab (674 cm ) is significantly smaller than nmax (7582 cm ),
confirming that the IVCT transition is localized and therefore
can be described as a Class II system in the Robin and Day
ꢀ1
II
[33]
,
20000 to ,22000 cm due to oxidation of the Ru centre to
classification.
The [Ru Cl (tpy) (TPA-2bpm)](PF ) complex was also
III
Ru . The second process involved the formation of a band at
2
2
2
6 2
ꢀ
1
,
15000 cm due to the localized p - p* transition of the
determined to be a localized mixed-valence class II system on
ꢀ1
ꢀ
1
ꢀ1
triarylamine radical cation in the ligand. The third process for all
ruthenium complexes except [Ru Cl (tpy) (TPA-2bpm)](PF )
analysis of the band at nmax 7783 cm (emax 2620 M cm
with a comparison of the line width at half height, Dn
)
¼
2
2
2
6 2
1/2
ꢀ1
involved a decrease in the intensities of the bands at ,15000 and
3495 cm with the theoretically calculated value, Dn1/28 ¼
ꢀ
1
6500 cm due to decomposition of the complex. Interestingly,
ꢀ1 ꢀ1
2
for [Ru Cl (tpy) (TPA-2bpm)](PF ) , a band in the NIR region
4240 cm . The value of 2Hab in this system, 1131.5 cm ,
which is higher than that for the TPA-2bpm ligand suggests that
although this system is still a class II compound, the two centres
are more strongly coupled in the Ru complex than in the ligand.
The IVCT bands in both TPA-2bpm and [Ru Cl (tpy) (TPA-
2
2
2
6 2
ꢀ
1
at 7740 cm was formed as the potential was decreased from
.0 to 0.9 V, which was indicative of an intervalence charge
1
transfer (IVCT) process and strongly suggests dimerization of
the complex through the unsubstituted para position on the
triarylamine core (Fig. 3). As the potential was decreased from
2
2
2
2bpm)](PF ) exhibit a small cut-off on the low-energy side
6
2
of the band, resulting in a slightly asymmetric Gaussian band.
This is characteristic of coupled systems where the Gaussian
shape of the band is retained, but is truncated at energies below
ꢀ1
0
.9 to 0.7 V, the bands at 7740 and ,15000 cm decreased in
intensity to reveal a spectrum that was similar to the starting
neutral spectrum.
[
21]
the value of 2Hab.
Intervalence Charge Transfer
EPR Spectroelectrochemistry
Analysis of the Gaussian-shaped IVCT bands in the NIR region
formed in the solution-state spectroelectrochemical spectra of
the TPA-2bpm ligand and [Ru Cl (tpy) (TPA-2bpm)](PF )
Application of a potential of 1.7 V during the EPR spectro-
electrochemical experiment for TPA-2bpm in [(n-C H ) N]
4
9 4
PF /CH Cl electrolyte resulted in a rapid change from a
6
2
2
2
6 2
2
2
complex due to dimerization was undertaken to determine
the extent of charge delocalization (Supplementary Material).
colourless to a deep orange–red solution (Fig. 4). The radical
was readily generated and exhibited a very strong EPR signal at
g ¼ 2.0046 (g indicates the g-factor, which is 2.0023 for the free
electron). On simulation of the EPR spectrum, it was revealed
ꢀ
1
TPA-2bpm exhibits a band centred at 7582 cm (n ) with
max
ꢀ
1
ꢀ1
.
an associated extinction coefficient (emax) of 881 M cm
(a)
(b)
∗
Q-band, 50 K
TPA-3bpm
TPA-2bpm
X-band, 5 K
X-band, RT
3480
3500
3520
3540
2.04
2.03
2.02
2.01
2.00
1.99
1.98
Field [G]
g
(c)
(d)
Fig. 4. EPR spectroelectrochemistry in [(n-C
4
H
9
)
4
N]PF
6
/CH
2
Cl
2
electrolyte of (a) TPA-2bpm and TPA-3bpm at room temperature (RT, 298 K) in
in [(n-C N]PF /CH CN electrolyte
solution at X-Band at a potential of 1.7 V (* indicates an impurity); (b) [Ru(tpy)Cl(TPA-3bpm)]PF
6
4
H
9
)
4
6
3
showing the spectrum of the radical in solution at RT of 298 K at X-band, as a frozen solution at 5 K at X-band and as a frozen solution at 50 K at
Q-band; and photos during the experiment of (c) TPA-2bpm; and (d) TPA-3bpm.

F
C. Hua et al.
that the signal arose from interaction of the radical with two
nitrogen nuclei, each exhibiting a hyperfine coupling value of
indicating that the radical generated was delocalized onto the
III
phenyl rings. The EPR signal due to Ru formed on oxidation
1
ilar to that reported by Kattnig et al. for a system containing two
linked triarylamine cores through a phenyl–ethynyl linker.
1.5 MHz (Supplementary Material). The signal was very sim-
was observed at 5 K at X-band and displayed axial anisotropy
(Supplementary Material) in addition to the presence of the
triarylamine radical cation (Fig. 4b).
[
34]
This, along with the previous observations from solution-state
electrochemical and UV-vis-NIR spectroelectrochemical
experiments strongly supported the formation of a dimer species
on oxidation of the triarylamine through the unsubstituted para
position on the phenyl ring.
Fluorescence
A fluorescence emission peak was observed for TPA-2bpm
(375 nm) and TPA-3bpm (368 nm) on excitation of a solution of
ꢀ1
the ligand in acetonitrile at 350 nm (28571 cm ) (Supplemen-
tary Material). The observed Stokes shifts were 70 and 60 nm
respectively for TPA-2bpm and TPA-3bpm. The oxidized
TPA-2bpm and TPA-3bpm ligands were fluorescent but
exhibited significant red shifts from their neutral states, emitting
fluorescence peaks at 463 nm for TPA-2bpm and 472 nm for
TPA-3bpm with corresponding Stokes shifts of 89 nm for TPA-
2bpm and 101 nm for TPA-3bpm.
As a potential of 1.7 V was applied to a solution of TPA-
bpm in [(n-C H ) N]PF /CH Cl electrolyte, a colour change
4 9 4 6 2 2
3
from yellow to deep green occurred with the appearance of an
EPR signal. A distinct lack of dimer formation for TPA-3bpm
was observed where the EPR signal (g ¼ 2.008) indicated
that the radical only interacted with one nitrogen nucleus (the
isotropic component of the hyperfine interaction, Aiso
1
¼
2.6 MHz) at the centre of the triarylamine ligand in addition
The ruthenium complexes with TPA-2bpm emitted a broad
fluorescence peak from 400 to 600 nm on excitation at 350 nm
to a hyperfine coupling interaction of 5.6 MHz due to the protons
that are proximal to the central nitrogen (Fig. 4a). The EPR
spectrum of the electrochemically generated radical of TPA-
(
6
Supplementary Material). The fluorescence peak at 400–
ꢀ1
00 nm (16670–25000 cm ) for [Ru (tpy) Cl (TPA-3bpm)]
2
2
2
3
bpm was additionally obtained as a frozen solution (Supple-
mentary Material). As the temperature was lowered from 200 to
70 K, a gradual transition from the solution-state to solid-state
(PF ) may be resolved into two overlapping peaks. An addi-
6 2
ꢀ1
tional fluorescence peak at 750 nm (13330 cm ) was observed
for both complexes on excitation into the MLCT band at 500 nm
that exhibited a very large Stokes shift of 250 nm. Luminescence
on excitation into the MLCT band of ruthenium terpyridine
complexes is well known and has resulted in their use as oxygen
1
spectrum was observed (Supplementary Material). The solid-
state spectrum exhibits rhombic anisotropy, clearly displaying
contributions from the x, y, and z axes (Supplementary Material).
The frozen-solution spectrum of TPA-3bpm was determined to
have g-factor values for N of g ¼ 1.997, g ¼ 2.007, g ¼ 2.017,
[35]
sensors and in biomedical applications.
x
y
z
All ruthenium complexes containing the TPA-3bpm ligand
exhibited fluorescence with emission bands at 746–750 nm on
excitation into the MLCT band (lex 490–495 nm), suggesting
that the fluorescence was a property resulting from interaction of
the ligand with the ruthenium centre (Supplementary Material).
The fluorescence was quenched for all complexes on chemical
and A ¼ 2.8 MHz in addition to a contribution from the
1
H present in the ligand of g ¼ 2.0067 and A ¼ 11.8 MHz.
EPR spectroelectrochemistry for the ruthenium complexes
with the TPA-2bpm ligand revealed a very broad EPR signal on
application of a positive potential (g ¼ 2.0065 for [Ru(tpy)Cl
(
2
TPA-2bpm)](PF ) and g ¼ 2.007 for [Ru (tpy) Cl (TPA-
6
2
2
2
oxidation with NOPF owing to oxidation of the triarylamine to
6
bpm)](PF ) ) with minimal hyperfine coupling (Supplementary
6 2
its radical cation. This is in accordance with previously observed
trends where the fluorescence can be switched off as a function
[36,37]
of the redox state.
Material). The hyperfine information was hidden by the line
width of the signal, which likely arose from the slow rate of
molecular tumbling of the complex in solution. A slight colour
change from dark purple to light purple–yellow was observed
when the positive potential was first applied to all Ru com-
Conclusions
II
III
plexes, corresponding to oxidation of Ru to Ru . As the
experiment progressed, the light colour generated was replaced
by a very dark green–purple corresponding to generation of
Two novel ligands, TPA-2bpm and TPA-3bpm, containing a
redox-active triarylamine core with the bispyrazolylmethane
moiety have been developed. Of particular interest was the
comparison of the redox properties between TPA-2bpm and
TPA-3bpm, where dimerization of TPA-2bpm occurred owing
to the unsubstituted para position present. Evidence for the
dimerization of TPA-2bpm was obtained using spectro-
electrochemical experiments, where formation of a low-energy
IVCT band (UV-vis-NIR) and the electron delocalization over
two chemically equivalent nitrogens (EPR) were observed. This
dimerization process was absent in TPA-3bpm where all para
sites of the phenyl rings are substituted. The combination of the
III
the triarylamine radical cation. The Ru species was not
able to be observed for [Ru(tpy)Cl(TPA-2bpm)](PF ) and
6
[Ru (tpy) Cl (TPA-2bpm)](PF ) at 130 K owing to the low
2 2 2 6 2
concentration of the species in addition to the broadening of the
signals typical of metal ions.
The EPR signal generated for ruthenium complexes contain-
ing the TPA-3bpm ligand contained the distinctive 1 : 1 : 1 triplet
signal for a radical localized on a nitrogen atom (Fig. 4b). The
elucidation of hyperfine information was possible owing to the
different rate of molecular tumbling in solution, as complexes
containing TPA-3bpm are significantly different in size and
shape from the TPA-2bpm complexes. All complexes exhibited
similar g-factor values, where a slight increase in the g value was
observed as more ruthenium centres were coordinated to the
ligand (Supplementary Material). The frozen-solution EPR
spectrum for [Ru(tpy)Cl(TPA-3bpm)]PF6 was obtained at
X- and Q-band frequencies to elucidate the small g anisotropy
present (Fig. 4 and Supplementary Material). There was a
TPA-2bpm and TPA-3bpm ligands with Ru(tpy)Cl yielded five
3
II
Ru terpyridine complexes with varying numbers of Ru
II
II
coordinated to each ligand. The Ru and the triarylamine
core were able to be oxidized at well-separated potentials,
allowing investigation of each of the distinct redox states of the
complexes. In particular, UV-vis-NIR and EPR spectro-
electrochemical experiments revealed that dimerization also
occurred in complexes with the TPA-2bpm ligand. The prop-
II
erties of the synthesized Ru complexes may lead to their use in
optoelectronic devices and dye-sensitized solar cells.
1
significant contribution from H in the ligand to the EPR signal

Electrochemically Dimerized Ruthenium Complexes
G
Experimental
bath for 30 min before the addition of pyrazole (6.20 g,
9
1.1 mmol), which yielded bubbling and a clear solution. This
General Considerations
was stirred at 08C for 1.5 h before the dropwise addition of
thionyl chloride (3.32 mL, 45.5 mmol) to yield a thick white
suspension. The reaction mixture was then stirred at room
temperature for 30 min before anhydrous cobalt(II) chloride
All chemicals and solvents were used as obtained without fur-
[38]
ther purification. Tris(p-formylphenyl)amine
and Ru(tpy)
were synthesized according to literature procedures.
,4 -(Phenylazanediyl)dibenzaldehyde was synthesized accord-
[
3
39,40]
Cl
4
0
(
3
118 mg, 0.911 mmol) and tris(p-formylphenyl)amine (1.00 g,
.04 mmol) were added to yield a mustard-yellow suspension.
[38]
ing to literature procedures with modification.
For experi-
ments requiring dry solvents, acetonitrile was dried over CaH2
and methanol was dried over magnesium/magnesium methox-
ide before being distilled under nitrogen. Toluene was obtained
from a PuraSolv solvent purification system and stored over
This was then heated at reflux for 30 h to yield a pale green
suspension before being cooled to room temperature and the
solvent removed under vacuum. The residue was dissolved in
dichloromethane and washed with water before being dried over
magnesium sulfate, filtered, and the solvent removed under
vacuum to yield a red solid. The crude product was purified by
column chromatography on silica (1 : 1 ethyl acetate/hexane,
gradient to 3 : 1 ethyl acetate/hexane) (1.35 g, 65 %). d (CDCl ,
˚
activated 4-A molecular sieves.
1
13
1
Solution-state H and C{ H} NMR spectra were recorded
on either a Bruker Avance300 or Avance500 spectrometer
1
operating at 300, 500 MHz for H and 75, 125 MHz for C.
13
1
13
H and C NMR chemical shifts were referenced internally to
H
3
3
5
00 MHz) 7.67 (s, 3H, H5), 7.62 (d, J
3
2.0, 4H, H6), 7.04 (d, J
2.0, 6H, H8), 7.53
H7–H8
residual solvent resonances. Spectra were recorded at 300 K and
1
3
d, J
(
8.5, 6H, H3), 6.89 (d,
H6–H7
H2–H3
chemical shifts (d), with uncertainties of ꢁ0.01 Hz for H and
3
3
JH2–H3 8.5, 6H, H2), 6.32 (t, J
13
1
2.0, 6H, H7). C{ H}
1
0.05 Hz for C, are quoted in ppm. Coupling constants (J)
3
H7–H6/H8
ꢁ
NMR (CDCl , 125 MHz) 147.8 (C1), 140.9 (C8), 130.6 (C4),
3
are quoted in Hertz. Deuterated solvents were obtained from
Cambridge Stable Isotopes and used as received. Mass spec-
trometry was carried out at the mass spectrometry analysis
facility at the University of Sydney on a Finnigan LCQ mass
spectrometer. Microanalyses were carried out at the Chemical
Analysis Facility – Elemental Analysis Service in the Depart-
ment of Chemistry and Biomolecular Science at Macquarie
University, NSW, Australia.
1
Calc. for C H N : C 68.51, H 4.86, N 26.63. Found: C 67.57,
29.8 (C6), 128.3 (C2), 124.3 (C3), 106.7 (C7), 77.6 (C5). Anal.
3
9 33 13
þ
H 4.80, N 25.46 %. m/z (ESI , CH CN) 706.07 (100 %);
3
þ
[
M þ Na] requires 706.29.
Synthesis of Ruthenium Complexes
Ru Cl (tpy) (TPA-2bpm)](PF )
[
2
2
2
6 2
Ru(tpy)Cl (82.0 mg, 0.186 mmol) and TPA-2bpm (50.0 mg,
3
.0930 mmol) were suspended in dry methanol (40.0 mL) and
N-methylmorpholine (1.5 mL) was added. The dark purple
suspension was heated at reflux under nitrogen for 22 h to yield
a dark solution, then cooled to room temperature. A saturated
Synthesis of Ligands
0
TPA-2bpm
A suspension of NaH (3.65 g, 60 % in mineral oil,
9
1.3 mmol) in dry THF (200 mL) was cooled in a water–ice
bath for 30 min before the addition of pyrazole (6.20 g,
1.1 mmol), which yielded bubbling and a clear solution. This
solution of KPF in water was added to the reaction mixture to
6
9
yield a dark purple–brown solid. This was filtered and the solid
washed with water before being dried. The crude product was
purified by silica column (19 : 1 : 0.1 CH CN/H O/KNO (sat.
was stirred at 08C for 40 min before the dropwise addition of
thionyl chloride (3.30 mL, 45.4 mmol) to yield a thick white
suspension. The reaction mixture was then stirred at room
3
2
3
solution in water)), the fractions containing the solid combined,
and the solution concentrated. A saturated solution of NH PF in
water was added to yield the product as a dark purple solid
temperature for 30 min before anhydrous cobalt(II) chloride
0
4
6
(
(
119mg,0.917mmol)and4,4 -(phenylazanediyl)dibenzaldehyde
0.750 g, 2.49 mmol) were added to yield a mustard-yellow
(40 mg, 29 %). d (CD CN, 500 MHz) 9.02 (s, 1H, H5a), 9.02 (s,
H
3
3
1H, H5), 8.54 (d, J
3
2.5, 1H, H21a), 8.53 (d, J
suspension. This was then heated at reflux for 30 h to yield a
pale green suspension before being cooled to room temperature
and the solvent removed under vacuum. The residue was
dissolved in dichloromethane and washed with water before
being dried over magnesium sulfate, filtered, and the solvent
removed under vacuum to yield a yellow oil. The crude product
was purified by column chromatography on silica (1 : 3 ethyl
2.5, 1H,
8.0, 2H,
2.5, 1H,
H–H
H–H
3
H21), 8.42–8.38 (m, 4H, H19 and H19a), 8.33 (d, J
H–H
H–H
3
H27), 8.08 (d, J
3
2.5, 1H, H13a), 8.06 (d, J
H–H
3
H13), 8.03 (t, J
3
8.0, 1H, H20a), 8.02 (t, J
8.0, 1H, H20),
4
7.8, J
H–H
H–H
3
7.89–7.85 (m, 4H, H6 and H8 and H26), 7.75 (dt, J
H–H
H–H
3
1.4, 1H, H14a), 7.70 (dt, J
4
7.8, J
1.4, 1H, H14), 7.58
H–H
H–H
3
(d, J
3
4.9, 1H, H24a), 7.55 (d, J
4.9, 1H, H24), 7.50–7.47
H–H
H–H
acetate/hexane, gradient to 1 : 1 ethyl acetate/hexane) (0.907 g,
(m, 4H, H16, H6a, and H8a), 7.36–7.33 (m, 4H, H25, H6a, and
1.5, 2H, H10), 6.99–6.97 (m,
3
8 %). d (CDCl , 500 MHz) 7.67 (s, 2H, H5), 7.63 (d, J
3
H8a), 7.23 (dd, J
4
6.5, J
6
1
8
8
4
1
1
1
5
H
3
H6–H7
H–H
H–H
3
.2, 4H, H6), 7.54 (d, J
3
1.8, 4H, H8), 7.26 (d, J
3
4H, H15 and H7a), 6.82 (d, J
3
9.0, 2H, H2a), 6.81 (d, J
H7–H8
H10–H11
H–H
H–H
3
.7, 1H, H11), 7.09 (d, J
3
8.0, 2H, H10), 7.08 (t, J
3
9.0, 2H, H2), 6.47 (d, J
3
1.5, 2H, H6 and H8), 6.25 (d, J
H10–H11
H11–H12
H–H
H–H
3
.0, 1H, H12), 7.03 (d, J
3
8.7, 4H, H3), 6.89 (d, J
3
9.0, 2H, H3a), 6.22 (d, J
3
9.0, 2H, H3), 6.11 (t, J
8.7,
H, H2), 6.33 (br s, 4H, H7). C{ H} NMR (CDCl , 125 MHz)
1.5, 2H,
H7). C{ H} NMR (CD CN, 125 MHz) 161.2 (C18, C22),
H2–H3
1
H2–H3
H–H
H–H
3
1
13
1
3
3
48.3 (C1), 146.8 (C9), 140.9 (C6), 130.2 (C4), 129.8 (C8),
29.7 (C11), 128.8 (C2), 125.8 (C10), 124.5 (C12), 123.5 (C3),
06.7 (C7), 77.7 (C5). Anal. Calc. for C H N : C 71.49, H
.06, N 23.45. Found: C 71.21, H 4.77, N 23.14 %. m/z (ESI ,
þ
160.0 (C23), 159.8 (C17), 154.6 (C14), 153.4 (C27), 149.3
(C1), 149.2 (C4), 148.9 (C6a and C8a), 146.3 (C9), 146.1 (C6
and C8), 137.8 (C6a and C8a, C6 and C8, C25), 137.0 (C15),
134.7 (C20), 131.3 (C10), 129.1 (C11), 128.2 (C26), 128.1 (C3),
127.6 (C12), 127.4 (C16), 124.6 (C24), 123.9 (C13), 123.1 (C2,
C19, C21), 109.2 (C7a), 108.8 (C7), 76.5 (C5). Anal. Calc. for
C H Cl F N P Ru: C 47.52, H 3.15, N 13.41. Found:
3
2 27 9
þ
CH CN) 560.00 (100 %); [M þ Na] requires 560.23.
3
TPA-3bpm
6
2
49
2 12 15 2
þ
A suspension of NaH (3.64 g, 60 % in mineral oil,
1.1 mmol) in dry THF (50.0 mL) was cooled in a water–ice
C 47.22, H 2.98, N 13.65 %. m/z (ESI , MeOH) 638.40
2
(100 %); [M – 2PF6] requires 638.59.
þ
9

H
C. Hua et al.
[
Ru Cl (tpy) (TPA-3bpm)](PF )
internal standard on completion of each experiment. All poten-
þ
3
3
3
6 3
tials are quoted in volts versus Fc /Fc.
Ru(tpy)Cl (77.4 mg, 0.176 mmol) and TPA-3bpm (40.0 mg,
3
0.0585 mmol) were suspended in dry methanol (40.0 mL) and
N-methylmorpholine (2.5 mL) was added. The dark purple
UV-Vis-NIR Spectroelectrochemistry
suspension was heated at reflux under nitrogen for 22 h, then
cooled to room temperature. A saturated solution of KPF in
Solution-state UV-vis-NIR spectroelectrochemistry over the
ꢀ
1
range of 3500–35000 cm was performed using a Cary5000
spectrophotometer interfaced to Varian WinUV software. In the
solution state, the absorption spectra of the electrogenerated
species were obtained in situ by the use of an optically semi-
transparent thin-layerelectrosynthetic (OSTLE) cell, path length
0.65 mm, mounted in the path of the beam of the spectrophoto-
meter. Solutions for the spectroelectrochemial experiment con-
tained 0.1 M [(n-C H ) N]PF /CH Cl or [(n-C H ) N]PF /
6
water was added to the reaction mixture to yield a dark purple–
brown solid. This was filtered and the solid washed with water
before being dried. The crude product was purified by silica
column (19 : 1 : 0.1 CH CN/H O/KNO (sat. solution in water)),
3
2
3
the fractions containing the solid combined, and the solution
concentrated. A saturated solution of NH PF in water was
added to yield the product as a dark purple solid (80.0 mg, 49 %).
4
6
4
9 4
6
2
2
4
9 4
6
3
d (CD CN, 500 MHz) 8.73 (d, J
H
8.5, 6H, H15 and H17),
8.0, 3H, H23), 7.93–
1.5, 6H, H6 and H8),
CH CN supporting electrolyte and ,1 mM of the compound.
3
H–H
3
3
.49–8.40 (m, 6H, H9, H16), 8.34 (d, J
8
7
7
1
6
6
Appropriate potentials were applied by using an eDAQ e-corder
410 potentiostat and the current was carefully monitored
throughout the electrolysis. By this method, the electrogenerated
species were obtained in situ, and their absorption spectra were
recorded at regular intervals throughout the electrolysis.
H–H
3
.89 (m, 9H, H5, H10, H22), 7.81 (d, J
H–H
3
.69–7.67 (m, 3H, H12), 7.38–7.36 (m, 3H, H11), 7.33 (d, J
H–H
3
.5, 3H, H20), 7.15 (t, J
3
6.0, 3H, H21), 6.93 (d, J
8.0,
8.0,
H–H
H–H
3
H, H2 and H3), 6.51 (br s, 6H, H6 and H8), 6.40 (d, J
H–H
3
H, H2 and H3), 6.13 (t, J
13
1
1.5, 6H, H7). C{ H} NMR
H–H
(CD CN, 125 MHz) 160.0 (C19), 158.9 (C14 and C18), 156.3
3
EPR Spectroelectrochemistry
(
C14 and C18), 154.6 (C13), 149.0 (C4), 146.3 (C6 and C8),
The procedure and cell set up used were as previously
[41]
1
(
1
(
39.0 (C5), 137.9 (C6 and C8, C10, C22), 137.1 (C12), 131.0
C1), 128.5 (C21), 128.4 (C11), 128.3 (C20), 125.5 (C2 and C3),
25.3 (C9, C23), 124.1 (C15 and C17), 124.0 (C23), 122.8
C16), 109.3 (C2 and C3), 108.9 (C7), 76.4 (C5). Anal. Calc. for
C H Cl F N P Ru : C 45.28, H 2.99, N 13.83. Found:
described.
A three-electrode assembly based on simple
narrow wires (A–M Systems) as electrodes where Teflon-coated
platinum (0.20 and 0.13 mm coated and uncoated diameters
respectively) and silver wires (0.18 and 0.13 mm coated and
uncoated diameters respectively) were used for the working and
quasi-reference electrodes respectively, and a naked platinum
wire (0.125 mm) for the counter electrode. The bottom 1 cm of
the Teflon-coated wires was stripped (using an Eraser Interna-
tional Ltd RT2S fine wire stripper). The working electrode was
positioned lowest such that the redox product of interest was
generated at the bottom of the tube and well separated from the
counter electrode. The electrodes were soldered to a narrow
three-core microphone wire. The cell used was made by flame-
sealing the tip of a glass pipette. The potential was controlled
with a portable mAutolab II potentiostat and the EPR spectra
obtained using an EMX Micro X-band EPR spectrometer with
8
4
66
3
18 22
3
3
þ
C 45.27, H 2.59, N 13.53 %. m/z (ESI , MeOH) 597.47
(100 %); [M – 3PF6] requires 597.73.
3þ
Physical Measurements
Mass Spectrometry
Low-resolution ESI mass spectra were acquired as a solution
ꢀ
1
in acetonitrile or methanol with a 100-mL min flow rate on a
Finnegan LCQ MS detector. Spectra were collected over the
mass range m/z 50 to 2000. An ESI spray voltage of 5 kV was
applied with a heated capillary temperature of 2008C and a
nitrogen sheath gas pressure of 60 psi (413 kPa).
1
.0-T electromagnet.
Infrared Spectroscopy (Diffuse Reflectance Infrared
Fourier Transform Spectroscopy)
Solution-State Fluorescence Spectroscopy
Fluorescence data were collected on a Cary Varian Eclipse
Fourier-transform (FT)-IR was performed on samples in a
ꢀ
fluorescence spectrophotometer. Excitation wavelengths were
determined by UV-vis-NIR spectra, and maximum wavelengths
deduced from emission–excitation spectra. The scan rate used
1
KBr matrix over the range 4000–400 cm on a Bruker Tensor
2
ꢀ1
7 FT-IR spectrometer with a resolution of 4 cm .
ꢀ
1
for all measurements was 120 nm min with a 1-nm data
interval. The fluorescence spectrum of the species of interest
was obtained from a solution of the compound in acetone or
acetonitrile in a quartz cuvette (1 ꢂ 1 ꢂ 1 cm) with excitation at
Electrochemistry
Solution-state electrochemical measurements were performed
using a Bioanalytical Systems BAS 100A electrochemical
analyser. Argon was bubbled through the electrolyte solution
3
80 nm, the emission spectrum obtained from 400 to 750 nm,
and slit widths of 2.5 mm, which were used for both excitation
and emission.
(
0.1 M [(n-C H ) N]PF in either CH CN or CH Cl ) contain-
4 9 4 6 3 2 2
ing a small sample of the compound of interest before the start of
the experiment. The cyclic voltammograms (CVs) were
recorded using a glassy carbon working electrode (1.5-mm
diameter), a platinum wire auxiliary electrode, and an Ag/Ag
wire quasi-reference electrode. Ferrocene was added as an
Crystallography
þ
†
TPA-2bpm. A colourless block-like crystal was mounted
on a SuperNova Dual Atlas diffractometer employing
†
˚
27 9
Formula C32H N , M 537.62, triclinic, P-1 space group (#02), a 9.9607(3), b 12.2145(3), c 12.9010(4) A; a 110.727(3), b 102.826(2), g 101.316(2)8;
˚
3
ꢀ3
˚
V 1364.85(7) A ; D 1.308 g cm ; Z 2; crystal size 0.188 by 0.144 by 0.1 mm; colour: colourless; habit: block; temperature 150(2) K; l(CuKa) 1.54178 A;
c
ꢀ1
m(CuKa) 0.652 mm ; T(CrysAlisPro, Agilent Technologies)min,max 0.93508, 1.00000; 2ymax 151.82; hkl range ꢀ12 12, ꢀ15 14, ꢀ16 16; N 24161, Nind 5651
2
˚
ꢀ ꢀ3
A .
(
R
merge 0.0196), Nobs 5022(I . 2s(I)), Nvar 370; residuals R
1
(F) 0.0557, wR
2
(F ) 0.1369, GoF(all) 1.076, Drmin,max ꢀ0.508, 0.570 e
2
2 2
– F
c
2 2 1/2
2
2
o
2
2
o
2
R
1
¼ S||F
o
| – |F
c
||/ S|F
o
| for F
o
. 2s(F
o
); wR
2
¼ (Sw(F
o
) / S(wF
c
) ) all reflections w ¼ 1/[s (F
) þ (0.0452P) þ 0.9594P] where P ¼ (F
þ 2F
c
)/3.

Electrochemically Dimerized Ruthenium Complexes
I
monochromated CuKa radiation generated from a sealed X-ray
tube. Cell constants were obtained from a least-squares refine-
ment against 14006 reflections located between 7.66 and
[7] A. Winter, S. Hoeppener, G. R. Newkome, U. S. Schubert, Adv. Mater.
2011, 23, 3484. doi:10.1002/ADMA.201101251
[
8] A. Wild, A. Winter, F. Schluetter, U. S. Schubert, Chem. Soc. Rev.
2
011, 40, 1459. doi:10.1039/C0CS00074D
1
51.418 2y. Data were collected at 150(2) K with c scans to
[
9] A. Winter, G. R. Newkome, U. S. Schubert, ChemCatChem 2011, 3,
1384. doi:10.1002/CCTC.201100118
10] J. Choi, H. M. Nguyen, S. Yoon, N. Kim, J.-W. Oh, F. S. Kim,
1
Pro
51.848 2y. The data processing was undertaken with CrysAlis
[42]
and subsequent computations were carried out with
[
[
43]
[42]
WinGX.
to the data.
The structure was solved in the triclinic space group P-1 (#2)
by direct methods with SHELXT,
with SHELXL-2014/7.
A multiscan absorption correction was applied
Mol. Cryst. Liq. Cryst. 2014, 600, 22. doi:10.1080/15421406.2014.
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and extended and refined
The non-hydrogen atoms in the
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CO;2-H
z
TPA-3bpm. A colourless plate crystal was coated in a thin
film of Paratone-N oil before being mounted on a diffractometer
with a ADSC Quantum 210r detector employing monochro-
mated synchrotron radiation generated from the MX1 Beamline
at the Australian Synchrotron in a stream of nitrogen at 100 K
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[
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where the Blu-Ice graphical interface was used.
[
The data
Cell constants were
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were reduced using the XDS package.
obtained from a least-squares refinement against 32066 reflec-
tions located between 2.80 and 64.008 2y. Data were collected at
[
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1
were carried out with WinGX.
00(2) K with c scans to 54.978 2y. Subsequent computations
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8
508. doi:10.1021/JA0512172
The structure was solved in the hexagonal space group P6 /m
3
[
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(#176) by direct methods with SHELXT,
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The non-hydrogen atoms in
[45]
the asymmetric unit were modelled with anisotropic displace-
ment parameters. A riding atom model with group displacement
parameters was used for the hydrogen atoms.
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Supplementary Material
[
Characterization, electrochemistry, UV-vis-NIR spectro-
electrochemistry, EPR spectroelectrochemistry, and fluores-
cence data are available on the Journal’s website.
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Acknowledgement
We gratefully acknowledge support from the Australian Research Council
and the Engineering and Physical Sciences Research Council UK National
Electron Paramagnetic Resonance Service at the University of Manchester.
The crystal structure of TPA-3bpm was obtained using the MX1 beamline at
the Australian Synchrotron, Victoria, Australia.
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z
˚
˚
3
/m space group (#176), a 11.903(2), b 11.903(2), c 14.466(3) A; g 1208; V 1775.0(7) A ; D
ꢀ3
Formula C39
H
33
N
13
O
1.62, M 709.65, hexagonal, P6
3
c
1.328 g cm
ꢀ1
;
˚
Z 2; crystal size 0.10 by 0.10 by 0.06 mm; colour: colourless; habit: plate; temperature 100(1) K; l(synchrotron) 0.7109 A; m(synchrotron) 0.087 mm ; T(XDS
(
Kabsch, 1993))min,max 0.6635, 0.7463, 2ymax 54.97; hkl range ꢀ15 15, ꢀ15 15, ꢀ18 18; N 27876, Nind 1410 (Rmerge 0.0701), Nobs 1286(I . 2s(I)), Nvar 152,
˚
ꢀ ꢀ3
1 2
residuals R
(F) 0.0761, wR
(F2) 0.1801, GoF(all) 1.124, Drmin,max ꢀ0.186, 0.189 e
A .
2
2 2
– F
c
2 2 1/2
c
2
2
o
2
2
o
2
R
1
¼ S||F
o
| – |F
c
||/ S|F | for F
o
o
. 2s(F
o
); wR
2
¼ (Sw(F
o
) /S(wF
) ) all reflections w ¼ 1/[s (F
) 1 (0.0560P) þ 1.1154P] where P ¼ (F
þ 2F
c
)/3.

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