Perylene-based, bis(terpyridine)-ru(ii) complexes: synthesis, electrochemical and photovoltaic properties

Article abstract of DOI:10.3987/COM-14-S(K)49

Perylene-based, terpyridine-Ru(II) complexes are synthesized and their electrochemical and photoelectrochemical properties are studied; their fabrication into dye-sensitized solar cells are described (DSSCs) and their resultant photovoltaic properties are

Full text of DOI:10.3987/COM-14-S(K)49

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HETEROCYCLES, Vol. 90, No. 1, 2015
HETEROCYCLES, Vol. 90, No. 1, 2015, pp. 502 - 514. © 2015 The Japan Institute of Heterocyclic Chemistry
Received, 27th June, 2014, Accepted, 29th July, 2014, Published online, 8th August, 2014
DOI: 10.3987/COM-14-S(K)49
PERYLENE-BASED,
BIS(TERPYRIDINE)-Ru(II)
COMPLEXES:
SYNTHESIS,
PROPERTIES
ELECTROCHEMICAL
AND
PHOTOVOLTAIC
Hany El-Batal,a Juan Manríquez Rocha,b Perla F. Méndez,b Luis A.
Godínez,b Kai Guo,a Xiaopeng Li,c Xiaocun Lu,a Chrys Wesdemiotis,a,c
Charles N. Moorefield,d and George R. Newkome*a,c,d
Departments of Polymer Sciencea and Chemistryc and The Maurice Morton
Institute for Polymer Science,d The University of Akron, Akron, OH, 44325, USA.
E-mail: newkome@uakron.edu; Centro de Investigación
Tecnológico en Electroquímica S. C.,b Querétaro, 76703, México
y
Desarrollo
Abstract – Perylene-based, terpyridine-Ru(II) complexes are synthesized and
their electrochemical and photoelectrochemical properties are studied; their
fabrication into dye-sensitized solar cells are described (DSSCs) and their
resultant photovoltaic properties are evaluated.
INTRODUCTION
Perylenediimides (PDIs) have been widely studied due to their stability and attractive electronic
properties.1-7 Elegant work by Würthner et al.8,9 has resulted in the construction of numerous functional
supramolecular architectures using ionic, H-bonding, π-π, and metal-ligand directed self-assembly.10,11
Terpyridine-metal-terpyridine [<tpy-M2+-tpy>, where tpy = 2,2':6',2"-terpyridine] connectivity12,13 is an
attractive approach to building functional materials due to the rich coordination chemistry and their
incorporation of redox, photophysical, and electrochemical properties into the resulting supramolecules. As
a result, terpyridine coordination has permitted the exploration of diverse materials used in construction of
solar devices.14,15 Their incorporation into a dendritic shell has given rise to unimolecular micelles16-20 and
bolaamphiphiles.9,21 This, along with the unique properties of perylene provided the inspiration to
synthesize perylene-containing tpy ligands7 and their RuII complexes. Herein, we report the synthesis of
heteroleptic, bis(terpyridinyl)perylene RuII complexes and their use in the fabrication of dye-sensitized
solar cell (DSSC) devices.

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RESULTS AND DISCUSSION
Synthesis began with the construction of aminoterpyridines 2 and 4,22 which were obtained from the
reduction of the corresponding known nitroterpyridines23 using Pd/C and hydrazine hydrate. The reaction
of perylenetetracarboxylic acid dianhydride (1) with 2 gave (51%) the linear bis(terpyridine)perylene
1
ligand24 3 (Scheme 1), which was confirmed with H NMR by absorptions at 8.79 (3',5'-tpyH), 8.74
(6,6"-tpyH), 8.30 (perH), and 1.27 ppm [C(CH3)3] as well as with electrospray ionization mass
spectrometry (ESI-MS) by a peak at m/z 1597.38 (calcd. [M+H]+ = 1597.64). The isomeric 525 was
1
similarly synthesized (60%) and exhibited H NMR peaks at 8.76 (3',5'-tpyH), 8.70 (6,6"-tpyH), 8.30
(perH), and 1.27 ppm [C(CH3)3] as well as ESI-MS peaks at m/z 1596.71 (calcd. [M]+ = 1596.64).
The known RuIII adduct 724 was obtained (88%) from terpyridine 6 by reaction with RuCl3·nH2O (Scheme
1). Complexes 8 and 9 were subsequently generated from adduct 7 (2.2 eq.) by treatment with
bisterpyridine ligands 3 and 5, respectively, in a MeOH:CHCl3 mixture and N-ethylmorpholine, as a
reducing agent. After counter ion exchange to give the PF6¯salt, the desired complexes were isolated (78%),
as dark red solids.
1
The H NMR spectrum for bis-complex 8 revealed a pair of singlets at 9.53 (3',5'-tpyHa) and 9.45
(3',5'-tpyHb) ppm [where, “a = inner” tpyHs and “b = outer” tpyHs; Scheme 1] that, as expected, were
shifted downfield ( = +0.65 Hz) in comparison to that of the free ligands 3 and 6. It also revealed a

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HETEROCYCLES, Vol. 90, No. 1, 2015
multiplet at 9.14 (3,3"-tpyHa and 3,3"-tpyHb) ppm, a peak at 7.80 (6,6"-tpyHa and 6,6"-tpyHb) ppm, with a
significant upfield shift resulting from the ring current shielding effect upon complexation, as well as two
singlets with an integration ratio of 1:6 at 2.90 (Ph-CH3) and 1.66 [C(CH3)3] ppm. In the case of the
1
isomeric 9, the H NMR spectrum showed three singlets with an integration ratio of 1:1 at 9.04
9.02 (3',5'-tpyHb), and 8.18 (perH) ppm along with two doublets at 8.66 (3,3"-tpyHa) and 8.63
ppm. The spectrum also revealed a multiplet at 7.41 (6,6"-tpyHa and 6,6"-tpyHb) ppm, in addition to two
singlets at 2.57 (Ph-CH3) and 1.32 [C(CH3)3] ppm, with an integration ratio of 1:6, respectively. The
structure was further confirmed by MALDI-TOF-MS peaks at m/z 2881.01 [M-PF6¯]1+ (Calcd. m/z =
2881.2) for 9.
In contrast, complex 13 was synthesized via a Suzuki coupling of dibromide 10 (Scheme 2) with
4'-terpyridinylphenylboronic acid (11) in a solvent mixture of toluene:H2O:t-BuOH (3:3:1) at 100 °C for 3
days. The solvent was evaporated in vacuo and the residue was column chromatographed (Al2O3) eluting
with CHCl3 and then recrystallized (5x) CHCl3:MeOH (1:1 v/v) to eliminate the isomeric
1,6-bis(terpyridine)-substituted perylene to afford (55 %) the pure 1,7-bis(terpyridine)perylene ligand 12,
1
as a red solid. The H NMR spectrum of 12 showed the following resonances: 8.88 (3',5'-tpyH), 8.79
(6,6"-tpyH), 8.74 (3,3"-tpyH), and 8.69 ppm (perH), in addition to the ESI-MS peak at m/z 1229.64 [M+H]+
(Calcd. m/z = 1229.54). Finally, bisterpyridine 12 was reacted with 7 in refluxing EtOH/CHCl3 (2:1)
solution with a catalytic amount of N-ethylmorpholine for 12 h, followed by counter ion exchange (NO3¯ to
1
PF6¯) to afford (78%) 13, as a dark red solid. The H NMR of bis-complex 13 exhibited three singlets at
9.35 (3',5'-tpyHa) and 9.18 (3',5'-tpyHb), and 8.69 (perH) ppm, two doublets at 8.91 (3,3"-tpyHa) and 8.83
(3,3"-tpyHb) ppm, and a multiplet at 7.54 (6,6"-tpyHa and 6,6"-tpyHb) ppm. A singlet at 2.54 ppm was
assigned to the Ph-CH3 moieties. ESI-MS further confirmed 13 with peaks at m/z 519.70 [M-4PF6¯]4+
(Calcd. m/z = 519.65), 741.28 [M-3PF6¯]3+ (Calcd. 741.19). Finally, complex 14 (Figure 1) was synthesized
according to the literature procedure.
ELECTROCHEMISTRY
The CV responses of complexes 8 and 9 (Figure 2A and 2B, respectively) each show two reversible waves
between -2.2 and -1.4 V associated with one-electron consecutive reductions for the two pairs of inner and

HETEROCYCLES, Vol. 90, No. 1, 2015
505
outer tpy moieties.26 Two additional reversible waves were also observed between -1.3 and -0.6 V that are
associated with two-electron consecutive reduction processes for perylene.27 Similarly, CV responses for
14 and 13 (Figures 2C and 2D, respectively) show irreversible waves for the consecutive reduction events
previously described for the tpy moieties (from -2.2 to -1.4 V) and perylene (from -1.3 to -0.6 V).
4+
4 PF6¯
14
Figure 1
Comparison of the cathodic behavior for the isomers 8 and 9 to that of 13 and 14 (Figures 2A and 2B vs
2C and 2D) strongly suggests that the reversible electrochemical responses for tpy and perylene moieties
are observed only if the -orbitals of these two types of groups are able to communicate electronically
through the peri-positions on the perylene units.27 Inspection of the oxidation processes (Figures 2A and
2B) reveals consecutive one-electron oxidations for the perylene and phenoxy moieties between 0 and
+0.50 V and a one-electron oxidation for the <tpyRuIItpy> moieties between +0.50 and +0.75 V,
respectively.25
Figure 2. CV responses for 8 (A), 9 (B), 14 (C), and 13 (D) using a glassy carbon electrode at 25°C (dE/dt
= 25 mVs-1). Dashed lines in (A) and (B) are the differential pulse voltammetry (DPV) responses for the
oxidative scans of 8 and 9, respectively.

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Thus, the low intensities observed for these two types of oxidation could be associated with very short
life-times for the perylene radical anions due to favorable e-transfer to RuIIItpy units. In contrast, a
comparison between Figures 2C and 2D show irreversible overlapped signals between +0.6 and +1.4 V,
possibly due to the consecutive oxidation reactions previously described for perylene and <tpyRuIItpy>.
PHOTOELECTROCHEMISTRY
As predicted by their electrochemical responses, a comparison between Figures 3A and 3B, indicates that
the output power obtained from DSSC assembled with 14 or 13 are higher than for 8 or 9. This behaviour is
reflected by the photovoltaic parameters compiled in Table 1; whereas, the global photovoltaic efficiencies
() follow the same tendencies. Despite the well-known photophysical and electrochemical properties of
both <tpyRuIItpy> and perylene, the observed low efficiencies of the DSSC can be attributed to the
presence of the two strong electron-withdrawing imide groups leading to a non-directional transfer7 of the
generated photoelectrons. As well, for all of the dyes studied, there is an absence of anchoring groups (i.e.,
CO2H) that are known to promote an efficient injection of photo-generated electrons into TiO2
photoanodes.29
Photo-stability for the sensitizers was studied by means of open-circuit-potential transients (ocp vs. time
plots) obtained for all the DSSC upon repetitive illumination-dark (ON-OFF) cycles. Figures 4-i and 4-ii
show the ocp transients obtained for 8 and 9 (Figures 4-iA and 4-iB) and for 14 and 13 (Figures 4-iiA and
4-iiB), respectively.
220000
115500
200
200
(B()B)
(A)
(A)
150
150
100
100
100
100
50
50
50
50
0
0
0
0
0
‐200
‐300
‐400
‐110000
200
300
400
0
0
‐100
100
‐200
200
‐300
300
‐400
400
0
voltage (mV)
voltage (mV)
voltage (mV)
voltage (mV)
Figure 3. Discharge curves obtained using DSSCs containing the dyes couples
(A): 8 (-o-) and 9 (--); and (B): 14 (-o-) and 13 (--) as sensitizers
These results indicate that the ocp for the DSSC containing 8 (Figure 4-iA) or 14 (Figure 4-iiA) is
constant under illumination, as function of time; however, the ocp for photocells sensitized by 9 (Figure
4-iB) and 13 (Figure 4-iiB) is rapidly deactivated under the same condition. These last results indicate
that the oxidized states for the dyes 9 and 13 are not efficiently reduced by I¯ ions contained in the cell
electrolyte.

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507
Table 1. Performance data obtained for DSSC having 8, 9, 13 or 14-dyed TiO2 electrodes
aFill-factor was calculated using ff =Pmax/Eocjsc, where Pmax is the maximum output power cell and jsc is
the short-circuit photocurrent.26 bGlobal photovoltaic conversion was calculated using  (%) =
[Pmax/(0.82P0)]100, where P0 is the power of the incident photon flux (9.21 mW/cm2)26 and the
constant 0.82 represents the effective transmittance when the photon flux passes through the OTE.
‐400
400
‐400
400
(ii)
(i)
(i)
(ii)
‐300
‐300
300
(B)
(A)
300
(A)
(B)
200
‐200
‐200
200
100
‐100
‐100
100
ON
ON
ON
ON
0
0
0
0
OFF
OFF
OFF
OFF
OFF
OFF
100
100
100
100
0
0
50
50
100
100
150
150
200
200
250
250
300
300
0
0
50
50
100
100
150
150
200
200
250
250
300
300
time (s)
time (s)
time (s)
time (s)
Figure 4. Open-circuit-potential (ocp) transients obtained for DSSC containing the dyes (i): 8 (A) and 9
(B) or (ii): 14 (A) and 13 (B), as sensitizers
2.4
2.4
2.2
2.2
2.0
2
1.8
1.8
1.6
1.6
1.4
1.4
1.2
1.2
1.0
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
4
4
0
00
0
4
4
5
5
0
0
5
5
0
0
0
0
5
5
5
5
0
0
6
60
0
0
0
650
650
wavelength (nm)
wavelength (nm)
Figure 5. Steady-state photocurrent spectra obtained from the DSSC containing 8 (-o-) and 14 (--), as
sensitizers

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To support the results shown in Figures 4-iA and 4-iiA, steady-state-photocurrent spectra (IPCE vs.
wavelength plots, Figure 5) were obtained and compared for the DSSCs containing the dyes. The
photocurrents subsequently obtained from photocells constructed with 8 and 14 predominately resulted
from injection by perylene at 470, 500, and 550 nm, respectively.30 Finally, the spectra shown in Figure 5
demonstrates that <tpyRuIItpy> units contained in 8 and 14 have no direct contribution to the
photocurrent generation, thereby suggesting that only perylene groups can establish a successful
electronic connection with Ti bonding orbitals in the TiO2 photoanodes.
1
13
In summary, dyes 8, 9, 13, and 14 were synthesized, their structures were confirmed using H and C
NMR, COSY, and ESI-MS. As well, their electrochemical, photoelectrochemical, and photovoltaic
properties were studied. These complexes were successfully implemented in the assembly of DSSCs for
which global conversion efficiencies were obtained. Photovoltaic results demonstrated that the perylene
moieties of these dyes were responsible for the photoactivated electron injection into the TiO2 collectors.
As well, the <tpyRuIItpy> complexes were simultaneously deactivated by the presence of the perylene
radical cations newly formed by photoactivation, thus inhibiting charge injection into the TiO2.
EXPERIMENTAL
Starting materials were commercially purchased and used without further purification. Thin layer
chromatography (TLC) was conducted on flexible sheets (Baker-flex) percolated with Al2O3 (IB-F) or
SiO2 (IB2-F) and visualized by UV light. Column chromatography was conducted using basic Al2O3,
Brockman Activity I (60-325 mesh) or SiO2 (60-200 mesh) from Fisher Scientific. Melting points were
determined on an Electrothermal 9100 heater. 1H and 13C NMR spectra were recorded on either a Varian
Mercury 300 or a Varian NMRS 500 spectrometer. Mass spectra were obtained on a Synapt HDMS
quadrupole/time-of flight (Q/TOF) mass spectrometer (Waters Corp., Milford, MA); the sprayed solution
was prepared by dissolving 1 mg of sample in 1 mL of a MeCN/MeOH (1:1) solvent mixture.
Preparation of the 8-, 9-, 13-, and 14-Sensitized Solar Cells. Nanoparticulate TiO2 electrodes
(523-roughness factor, , and 5 m thick, d, estimated according to measurements of the electroactive
area, Ae, and perfilometry, respectively) were obtained by electrophoretic deposition of TiO2
nanoparticles (P25 Degussa, 21 nm diameter), as previously reported. Cathodes were obtained, as
follows: 8 L/cm2 of a 10 mM H2PtCl66H2O (Strem Chemicals, 99.9%-Pt) solution in Me2CHOH (J.T.
Baker, 99.97%) was homogeneously spread on the surface of optically transparent electrodes (OTE)
based on indium-doped tin oxide (TEC15, Hartford Glass Co., USA). The cathodes were subsequently
dried at 25 °C and finally annealed in air at 380 °C for 30 min. TiO2 electrodes were dyed by immersion
in 0.40 mM solutions of (a) 8 and 9 both in MeOH (J. T. Baker, HPLC grade), (b) 14 in MeOH/CHCl3
(3:1) or (c) 13 in MeOH/CHCl3 (5:1), at 25 °C for 6 days. DSSCs were assembled in a sandwich
arrangement using a 160 m-thick o-ring (6 mm i.d.), home-made from a commercial transparency sheet

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(CG3700 3M, typically used as projecting transparencies) in order to avoid premature short circuit. A
solution of 0.3 M LiI (Aldrich, 99.9%) + 0.015 M I2 (J.T. Baker, ACS reagent) in propylene carbonate
(Aldrich, 99.7%) was employed as the electrolytic medium in the photovoltaic cells. An effective
geometric area of 0.28 cm2 was illuminated for all the photoelectrochemical experiments.
Electrochemistry. Cyclic voltammetry (CV) experiments were performed at 25 °C and 25 mV/s by
means of a BAS Epsilon potentiostat-galvanostat. A glassy carbon working-disc-electrode (1.5
mm-diameter) was immersed in a typical three-electrode cell containing DMF (99.8 %, J.T. Baker) +
0.1M Bu4NPF6 (Fluka, 98%) for testing complexes 8 and 9. Electrolytic mixtures of MeOH/CHCl3 (5:1)
+ 0.1M Bu4NPF6 and MeOH/CHCl3 (3:1) + 0.1M Bu4NPF6 were used for obtaining the CV responses for
samples 13 and 14, respectively. Experimental setup was completed when silver and platinum wires were
inserted in the electrochemical cell as pseudo- and counter-electrodes, respectively. All solutions were
purged with ultra-pure nitrogen (Praxair, 99.999%) for 15 min. prior to conducting the experiments.
Potentials were referenced to the ferrocinium/ferrocene redox scale (denoted as Fc+  Fc). PDIs are stable,
electron-deficient molecules, which are difficult to oxidize and easy to reduce. Scheme SI-A shows the
one electron-reversible oxidation (as revealed by CV) and Scheme S1-B shows the reduction process
reported for PDI.31
Photoelectrochemistry. Discharge curves were obtained for the DSSCs utilizing a variable resistance of
52 k upon polychromatic illumination emitted by a MR16 50W 12V lamp (GE) equipped with an EXN
dichroic reflector to diffuse the light. Power of the light source was 9.21 mW/cm2 (ca. 0.1 Sun).
Steady-state photocurrent spectra were obtained upon monochromatic illumination (400 - 650 nm) using a
6257 100W Xe lamp coupled to a 77250 monochromator, both purchased from Thermo-Oriel and
calibrated by means of a 17043 Eppley Thermopile. Incident-photon-to-current efficiencies (IPCE) were
estimated according to Eq. 1, where , jph, and I0, denote incident photon wavelength (in nm)
photocurrent density (in A/cm2), and incident photon flux (in W/cm2), respectively. The constant 0.82
corresponds to the effective transmittance of the incident photon flux through the OTE. All these
experiments were conducted on an IM6 BAS-Zahner potentiostat-galvanostat in order to measure
open-circuit-potentials or steady-state-photocurrents.

1240eV  nm jph,

(Equation 1)
IPCE

 

0.82I0,
General procedure for the synthesis of terpyridine-perylene ligands 3 and 4. A mixture of
1,6,7,12-tetra(p-t-butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bis(anhydride) 1 (500 mg, 0.5
mmol), 4- or 3-aminophenylterpyridine 2 or 4 (1.31 g, 4.06 mmol) in quinoline (50 mL) was stirred at
220 ºC under argon for 3 days. The mixture was cooled to 25 ºC, precipitated with AcOH (50 mL),
filtered, and washed with water, and then MeOH. The product was column chromatographed (Al2O3)

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eluting with a mixture of CHCl3/hexane (2:1).
N,N'-Bis[4-([2,2':6',2"]terpyridin-4'-yl)phenyl]-1,6,7,12-tetra(p-t-butylphenol)perylene-3,4:9,10-
1
tetracarboxylic acid bisanhydride (3): red powder, 51%; mp > 350 ºC; H NMR (300 MHz, CDCl3) δ
8.79 (s, 4H, 3',5'-tpyH), 8.74 (d, 4H, J = 4.2 Hz, 6,6"-tpyH), 8.68 (d, 4H, J = 7.8 Hz, 3,3"-tpyH), 8.30 (s, 4H,
perH), 8.06 (d, 4H, J = 8.4 Hz, PhH), 7.89 (dd, 4H, J1 = J2 = 7.8 Hz, 4,4"-tpyH), 7.43 (d, 4H, J = 8.4 Hz,
PhH), 7.36 (dd, J1 = 7.8 Hz, J2 = 4.2 Hz 4H, 5,5"-tpyH), 7.25 (d, 8H, J = 9.0 Hz, ArH), 6.88 (d, 8H, J = 9.0
Hz, ArH), 1.27 (s, 36 H, CH3); 13C NMR δ 163.75, 156.40, 156.28, 153.07, 149.68, 149.37, 147.70, 139.19,
137.09, 136.21, 133.41, 129.44, 128.46, 126.93, 124.06, 122.79, 121.61, 121.08, 120.51, 120.05, 119.60,
119.27, 105.23, 34.59, 31.65; ESI-MS: m/z 1597.38 (calcd. [M+H]+ = 1597.64).
N,N'-Bis[3-([2,2':6',2"]terpyridin-4'-yl)phenyl]-1,6,7,12-tetra(p-t-butylphenol)perylene-3,4:9,10-
1
tetracarboxylic acid bisanhydride (5): red powder, 60%; mp > 350 ºC; H NMR (500 MHz, CDCl3) δ
8.76 (s, 4H, 3',5'-tpyH), 8.70 (d, 4H, J = 4.7 Hz, 6,6"-tpyH), 8.66 (d, 4H, J = 7.8 Hz, 3,3"-tpyH), 8.3 (s,
4H, perH), 8.02 (d, 2H, J = 7.1 Hz, PhH), 7.86 (dd, 4H, J1 = J2 = 7.8 Hz, 4,4"-tpyH), 7.83 (s, 2H, PhH),
7.67 (dd, 2H, J1 = J2 = 7.1 Hz, PhH), 7.37 (d, 2H, J = 7.1 Hz, PhH), 7.33 (dd, J1 = 7.8 Hz, J2 = 4.7 Hz,
13
4H, 5,5"-tpyH), 7.25 (d, 8H, J = 9.1 Hz, ArH), 6.89 (d, 8H, J = 9.1 Hz, ArH), 1.27 (s, 36 H, CH3); C
NMR δ 163.54, 156.16, 156.03, 152.90, 149.21, 149.11, 147.39, 139.92, 136.77, 136.05, 133.18, 129.85,
129.18, 126.67, 123.78, 122.56, 121.30, 119.37, 118.91, 105.02, 34.35, 31.42; ESI-MS: m/z 1596.71
(calcd. [M]+ = 1596.64).
[Ru(6)Cl3] (7). 4'-(4-Methylphenyl)[2,2':6',2"]terpyridine (6; 200 mg, 890 µmol) was treated with
RuCl3·3H2O (251.7 mg, 1.21 mmol) in EtOH (20 mL), then the suspension was refluxed for 12 h. After
the mixture was cooled, the resultant dark brown solid was filtered, washed with cold EtOH, and dried in
vacuo to give 7: 290 mg (88%). This material was used without further purification.
General procedure for the synthesis of complexes 8, 9, and 13: Bis(terpyridine) ligand (3, 5 or 12)
(40 mg, 31 µmol) was added to a suspension of RuIIItpy 7 (25 mg, 69 µmol) in a mixed solvent (20 mL)
of EtOH/CHCl3 (2:1), then N-ethylmorpholine (500 µL) was added. The mixture was refluxed for 12 h.
After cooling, the resulting deep red solution was filtered (Celite), solvent was removed in vacuo and the
residue was column chromatographed (SiO2), eluting with H2O: KNO3:MeCN (1:1:35). The counter ion
was exchanged by adding NH4PF6, and then the product was filtered, washed with water and dried in
vacuo.
[(3)Ru2(6)2][PF6]4 (8): red powder, 50 mg (78%), mp > 350 °C; 1H NMR (500 MHz, CD3OD) δ: 9.53 (s,
4H, 3',5'-tpyH), 9.45 (s, 4H, 3',5'-tpyH), 9.14 (m, 8H, 3,3"-tpyH), 8.71 (d, 4H, J = 8.0 Hz, PhH), 8.67 (s,
4H, perH), 8.45 (d, 4H, J = 8.0 Hz, PhH), 8.36 (m, 8H, 4,4"-tpyH), 8.02 (d, 4H, J = 8.0 Hz, PhH), 7.90 (d,
4H, J = 8.0 Hz, PhH), 7.80 (m, 8H, 6,6"-tpyH), 7.65 (m, 16H, ArH, 5,5"-tpyH), 7.31 (d, 8H, J = 8.0 Hz,
ArH), 2.90 (s, 6H, CH3), 1.66 (s, 36H, CH3); 13C NMR δ: 163.56, 157.86, 157.80, 155.01, 151.63, 149.36,
147.99, 147.45, 141.14, 138.30, 138.25, 137.17, 136.80, 133.14, 133.03, 130.19, 129.88, 127.82, 127.70,

HETEROCYCLES, Vol. 90, No. 1, 2015
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126.46, 124.72, 124.63, 121.54, 121.04, 121.01, 120.99, 120.08, 120.05, 119.69, 119.15, 34.04, 30.92,
29.31; ESI-MS (m/z): 2881.1 [M - PF6¯]1+ (Calcd. m/z = 2881.5), 863.5 [M - 3PF6¯)]3+ (Calcd. m/z =
863.6), 611.4 [M - 4PF6¯)]4+ (calcd. m/z = 611.5).
[(5)Ru2(6)2][PF6]4 (9): red powder, 50 mg (78%), mp > 350 °C; 1H NMR (500 MHz, CD3CN) δ 9.04 (s,
4H, 3',5'-tpyH), 9.02 (s, 4H, 3',5'-tpyH), 8.66 (d, 4H, J = 8.0 Hz, 3,3"-tpyH), 8.63 (d, 4H, J = 8.0 Hz,
3,3"-tpyH), 8.32 (d, 2H, J = 7.5 Hz, PhH), 8.18 (s, 4H, perH), 8.14 (m, 8H, PhH), 7.92 (m, 8H,
4,4"-tpyH), 7.64 (d, 2H, J = 7.5 Hz, PhH), 7.58 (d, 4H, J = 8.0 Hz, PhH), 7.41 (m, 8H, 6,6"-tpyH), 7.36 (d,
8H, J = 7.5 Hz, ArH), 7.16 (m, 8H, 5,5"-tpyH), 6.96 (d, 8H, J = 7.5 Hz, ArH), 2.57 (s, 6H, CH3), 1.32 (s,
36H, CH3); 13C NMR δ: 163.50, 157.80, 157.73, 156.05, 155.26, 154.95, 152.61, 151.57, 149.29, 147.38,
141.08, 138.18, 137.10 136.73, 133.07, 132.6, 130.13, 129.81, 128.42, 127.75, 127.67, 127.19, 126.42,
124.57, 122.12, 12.47, 120.97, 120.92, 120.01, 119.62, 119.08, 33.97, 30.93, 29.24; MALDI-TOF-MS
(m/z): 2881.0 [M - PF6¯]1+ (calcd. m/z = 2881.2).
1,6/1,7-Dibromo-3,4,9,10-perylenetetracarboxylic dianhydride.31 A mixture of 3,4,9,10-perylene-
tetracarboxylic dianhydride (4 g, 10 mmol) and H2SO4 (60 mL) was stirred at 55 ºC for 18 h. Next I2 (80
mg, 300 µmol) was added and the mixture was stirred for 5 h at 55 ºC. Br2 (3.5 g, 20 mmol) was added,
the reaction mixture was stirred for 48 h at 85 ºC, followed by cooling to 0 ºC. Excess Br2 was removed
using air stream in the hood. The product was precipitated with cold water (30 mL), filtered, washed with
water, EtOH and then dried in vacuo to afford (89%) an orange powder: 5 g. The product was used in the
next step without further purification.
N,N'-Bis(n-octyl)-1,6/1,7-dibromo-3,4,9,10-perylenetetracarboxydiimide32,33 (10). To a mixture of
1,6/1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride (2.5 g, 4.5 mmol) and n-octylamine (5.8 g,
44.8 mmol), was added a mixture of 2-BuOH:H2O (80 mL, 1:1). The reaction mixture was stirred under
argon at 65 ºC for 12 h, cooled to 25 ºC, precipitated with MeOH (150 mL), and filtered. The product was
dried in vacuo and column chromatographed (SiO2) eluting with CHCl3 to give 10, as an orange powder:
5 g (89 %); 1H NMR (500 MHz, CDCl3) δ 9.43 (d, 4H, J = 8.0 Hz, perH ), 8.87 (s, 4H, perH), 8.65 (d, 4H,
J = 8.0 Hz, perH), 4.20 (m, 8H, CH2), 1.75 (m, 8H, CH2), 1.44-1.26 (m, 48H, CH2), 0.89 (t, 12H, CH3);
13C NMR δ 163.39, 163.01, 162.51, 162.14, 138.27, 138.15, 133.32, 133.08, 132.93, 132.52, 130.16,
130.02, 129.36, 128.64, 128.27, 127.88, 127.08, 123.54, 123.35, 122.92, 122.61, 121.79, 120.97, 41.16,
41.04, 40.93, 32.04, 29.54, 29.43, 28.30, 27.38, 27.33, 27.29, 22.86, 14.31; MALDI-TOF-MS: m/z 770.20
(calcd. M+ = 770.13).
N,N'-Bis(n-octyl)-1,7-di[4-([2,2':6',2"]terpyridin-4'-yl)phenyl]-3,4,9,10-perylenetetracarboxydiimide
(12). To a mixture of 10 (250 mg, 500 μmol) and 4'-(4-boronatophenyl)[2,2':6',2'']terpyridine 11 (485 mg,
1.3 mmol) in toluene: t-BuOH:H2O (2:1:1; 80 mL), was added K2CO3 (3.5 g, 27.4 mmol). The system
was freeze-pump-thawed three times and backfilled with argon; then Pd(PPh3)2Cl2 (16 mg) was added.
After refluxing for 72 h under argon, the mixture was cooled to 25 °C, solvent was removed in vacuo and

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the residue was dissolved in CHCl3 and filtered. After concentration in vacuo, the residue was purified by
column chromatography (Al2O3) eluting with CHCl3, followed by recrystallization from CHCl3/MeOH
(5x) to give (31%) 15, as a red solid: mp > 300 °C; 1H NMR (500 MHz, CDCl3) δ 8.88 (s, 4H, 3',5'-tpyH),
8.79 (d, 4H, J = 4.5 Hz, 6,6"-tpyH), 8.74 (d, 4H, J = 8.0 Hz, 3,3"-tpyH), 8.69 (s, 2H, perH), 8.23 (d, 2H, J
= 8.0 Hz, perH) , 8.11 (d, 4H, J = 8.0 Hz, PhH), 7.95 (m, 6H, perH, 4,4"-tpyH), 7.76 (d, 4H, J = 8.0 Hz,
PhH), 7.42 (dd, J1 = 8.0 Hz, J2 = 4.5 Hz, 4H, 5,5"-tpyH), 4.20 (t, 4H, J = 8 Hz, CH2), 1.43-1.27 (m, 23H,
13
CH2), 0.87 (m, 6H, CH3); C NMR δ 163.55, 163.42, 140.44, 135.30, 134.90, 133.36, 132.88, 130.60,
130.12, 129.86, 129.46, 129.42, 127.98, 124.71, 122.66, 122.34, 40.81, 31.99, 29.51, 29.36, 28.32, 27.29,
22.79, 14.23; ESI-MS: m/z 1229.64 (calcd. [M+H]+ = 1229.54).
[(10)Ru2(6)2][PF6]4 (13): red powder, (78%), mp > 350 °C; 1H NMR (500 MHz, CD3OD): δ 9.35 (s, 4H,
3',5'-tpyH), 9.18 (s, 4H, 3',5'-tpyH), 8.91 (d, 4H, J = 8.0 Hz, 3,3"-tpyH), 8.83 (d, 4H, J = 8.0 Hz,
3,3"-tpyH), 8.69 (s, 2H, perH), 8.49 (d, 4H, J = 8.0 Hz, PhH), 8.26 (d, 2H, J = 8.0 Hz, perH), 8.13 (d, 4H,
J = 8.0 Hz, PhH), 8.02-7.96 (m, 14H, PhH, perH, 4,4"-tpyH), 7.54 (m, 8H, 6,6"-tpyH), 7.51 (d, 4H, J =
8.0 Hz, PhH), 7.30 (m, 8H, 5,5"-tpyH), 4.23 (t, 4H, CH2), 2.54 (s, 6H, CH3), 1.77 (m, 8H, CH2),
1.46-1.25 (m, 23H, CH2), 0.86 (m, 6H, CH3); 13C NMR δ 162.72, 157.84, 157.75, 155.14, 155.12, 154.84,
151.62, 151.35, 148.88, 140.62, 137.94, 137.87, 137.78, 137.77, 137.74, 133.09, 127.42, 127.36, 126.75,
126.68, 124.64, 124.31, 121.37, 121.35, 120.76, 31.24, 28.71, 28.60, 28.54, 27.44, 26.53, 21.96, 20.18,
13.03; ESI-MS (m/z): 519.70 [M-4PF6¯]4+ (calcd. m/z = 519.65), 741.20 [M-3PF6¯]3+ (calcd. m/z =
741.19).
ACKNOWLEDGEMENTS
The authors gratefully thank the National Science Foundation (GRN CHE-1151991; CW CHE-1308307)
and the Ohio Board of Regents. The Mexican Council for Science and Technology is also gratefully
acknowledged for its financial support (CONACyT; 106000). P. F. M. gratefully acknowledges
CONACyT for her Ph. D. scholarship (104180).
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