New dyads using (metallo)porphyrins as ancillary ligands in polypyridine ruthenium complexes. Synthesis and electronic properties

Article abstract of DOI:10.1039/c2dt31656k

Porphyrins bearing enaminoketones at their periphery have been used as ancillary ligands in ruthenium complexes. Free base, nickel and zinc porphyrins were successfully coordinated to Ru(bpy)₂Cl₂ under microwave irradiation. The posi

Full text of DOI:10.1039/c2dt31656k

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PAPER
New dyads using (metallo)porphyrins as ancillary ligands in polypyridine
ruthenium complexes. Synthesis and electronic properties†
Fabien Lachaud,a Christophe Jeandon,b Antonio Monari,c Xavier Assfeld,c Marc Beley,a Romain Ruppert*b
and Philippe C. Gros*a
Received 24th July 2012, Accepted 30th August 2012
DOI: 10.1039/c2dt31656k
Porphyrins bearing enaminoketones at their periphery have been used as ancillary ligands in ruthenium
complexes. Free base, nickel and zinc porphyrins were successfully coordinated to Ru(bpy)2Cl2 under
microwave irradiation. The positive contribution of the ruthenium complex was demonstrated by the
complexes’ wide absorption domains that covered the 500–600 nm region where the parent porphyrins
did not absorb. Electrochemical as well as computational data revealed an efficient electronic
communication between the porphyrins and the ruthenium cation in the dyads.
ligands.18 Another route is to use a different ancillary ligand. As
a consequence, photoactive polyazine ruthenium complexes have
Introduction
The unequaled photochemical properties of chlorophyll and its
central role in natural photosynthesis have led researchers to
mimic it for the development of light driven processes. As a con-
sequence, the chemistry of metalloporphyrins became a wide
field of investigation with many applications such as photo-
dynamic therapy (PDT),1 photophysics2,3 or catalysis.4
An emerging area is the coordination of metals at the por-
phyrin periphery in order to design supramolecular arrangements
or promote synergetic electronic effects.5 Due to their photo-
physical and redox properties as well as electron transfer and
light harvesting ability,6–9 ruthenium–polypyridine complexes
are highly important coordination compounds and ideal candi-
dates for photosensitization in several applications exploiting
light energy such as dye-sensitized solar cells,10–13 switches,14,15
or molecular engines.16,17 A critical issue to be addressed
especially in the framework of solar energy conversion is to
design sensitizers ensuring an optimal absorption of the solar
spectrum. One way to reach this goal is to chemically modify the
polypyridine ligands with electron-donating and π-delocalized
moieties as done successfully by some of us on bipyridine
been assembled with metalloporphyrins to obtain additive elec-
tronic effects from each partner. An examination of the literature
shows that the main route to prepare the target mixed compounds
involves covalent binding of a coordinating azine to the por-
phyrin and subsequent reaction with the appropriate ruthenium
complex. Examples have been reported using porphyrin–(poly)-
pyridines19–23 and fused porphyrin–phenanthroline ligands.24
Recently, some of us have reported the synthesis of porphyrins
and metalloporphyrins bearing conjugated chelating sites at their
periphery.25–27 These compounds were next used to build metal
ions linked dimers exhibiting an efficient porphyrin–porphyrin
electronic interaction.28–31 Yanagida and colleagues32 showed
that NCS groups in Ru(dcbpy)2(NCS)2 dye (N3)33 could be
replaced advantageously by an acac (acetylacetonate) ligand.
Therefore porphyrins bearing enaminoketones could be seen as
π-delocalized analogues of acac and thus could act as anten-
nae34,35 for enhancing light harvesting in dye sensitized solar
cells. Thus we decided to examine the role of these functional
porphyrins as ancillary ligands in ruthenium complexes. Due to
a minimized distance between both partners, enhanced energy
transfer and thus better light harvesting are expected. To our
knowledge this approach has never been reported for the prep-
aration of porphyrin–ruthenium complexes dyads. Herein we
report the preparation and characterization of the new complexes
C1, C2 and C3 (Fig. 1).
aGroupe SOR, SRSMC, Université de Lorraine, CNRS, Faculté des
Sciences, Boulevard des Aiguillettes, F-54506 Vandoeuvre-Lès-Nancy,
France. E-mail: philippe.gros@univ-lorraine.fr;
Fax: +33 (0)383684785; Tel: +33 (0)383684979
bLaboratoire LCAC, Institut de Chimie, UMR 7177 CNRS, Université de
Strasbourg, 1 rue Blaise Pascal, 67070 Strasbourg, France.
E-mail: rruppert@unistra.fr; Tel: +33 (0)368851700
cEquipe CBT, SRSMC, Nancy Université, CNRS, Faculté des Sciences,
Boulevard des Aiguillettes, F-54506 Vandoeuvre-Lès-Nancy, France.
E-mail: antonio.monari@univ-lorraine.fr; Fax: +33 (0)383684371;
Tel: +33 (0)383684380
Results and discussion
1. Synthesis
†Electronic supplementary information (ESI) available: NMR spectra of
P3 and C2, HR mass spectra of C1, C2 and C3. Cyclic voltammograms
for oxidation and reduction of P1, P3, C1, C2 and C3. Emission spectra
of P1, P3, C1 and C3. CCDC 893819. For ESI and crystallographic
data in CIF or other electronic format see DOI: 10.1039/c2dt31656k
The starting free base porphyrin P1 was prepared according to
previously published procedures and obtained in good yields
after amination of ketone 1.27 Reaction of P1 with Ni(acac)2 or
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Scheme 2 Synthesis of complexes C1–C3.
Fig. 1 Complexes studied in this work.
Table 1 Absorption and emission data of porphyrins and ruthenium
complexes
λabs-max(nm)a
Compound
(ε/103 L mol−1 cm−1
)
Transitions
λem-max a (nm)
P1
710 (6.8)
Q-band
Q-band
Q-band
Soret
π–π*
π–π*
n.d.
726
726
726
614 (20.6)
485 sh (47.7)
452 (104.8) Soret
395 (44.4)
367 (42.9)
318 (25.5)
292 (23.3)
650 (18.5)
598 (9.8)
458 (96.4)
400 (28.1)
365 (24.3)
666 (17.5)
615 (10.5)
570 (11.0)
488 sh (48.8)
470 (100.5)
393 (33.3)
314 (24.7)
285 (22.6)
671 (6.9)
578 (16.8)
536 (20.7)
438 (54.5)
362 (22.4)
293 (38.3)
763 (4.8)
529 (22.2)
478 (23.1)
435 (35.3)
292 (39.1)
765 (6.0)
P2
P3
Q-band
Q-band
Soret
π–π*
π–π*
Q-band
Q-band
Q-band
Soret
n.d.
n.d.
n.d.
Scheme 1 Synthesis of P1, P2 and P3.
713
713
713
713
713
C1
Q-band
Q-band
MLCT
Soret
π–π* (bpy)
712
674; 712
674; 712
674; 712
C2
C3
Q-band
Q-band
MLCT
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
n.d.
570
Fig. 2 . X-Ray structure of P2.
Soret
π–π* (bpy)
Q-band
Q-band
MLCT
Soret
π–π* (bpy)
682 (7.8)
Zn(OAc)2 gave respectively the metalated porphyrins P2 and P3
in almost quantitative yields (Scheme 1).36
516 (23.8)
451 (28.9)
395 (19.3)
353 (18.8)
292 (39.6)
580; 637 sh; 713
560; 637 sh; 707
Single crystals suitable for X-ray characterization were
obtained for the nickel derivatives P2 (see Fig. 2).37 The coordi-
nation around the nickel(II) ion is square planar with four Ni–N
distances equal to 1.90 or 1.91 Å. The porphyrin aromatic ring is
ruffled as observed in most known structures of nickel porphyr-
ins. The external enaminoketone chelating site was coplanar
with the aromatic part of the molecule and intra (NH–O) and
intermolecular hydrogen bonds (NH–O, see ESI†) were clearly
present: the N–O distances were equal to 2.89 Å (intra) and
2.85 Å (intermolecular).
a Dichloromethane and acetonitrile were used as solvents for P1, P2, P3
and C1, C2, C3 respectively.
irradiation was continued. The expected complexes C1, C2 and
C3 were obtained in 21, 16 and 18% yield respectively after
purification by column chromatography (Scheme 2).
The porphyrins and corresponding complexes were then
studied by UV-Vis spectroscopy and electrochemistry. All data
for these new compounds are listed in Tables 1 and 2.
Complexes C1, C2 and C3 were synthesized by reacting first
the appropriate porphyrin (1 equiv.) with Ru(DMSO)4Cl2 in
DMF under microwave irradiation. To the crude mixture thus
obtained was added 2,2′-bipyridine (2 equiv.) and microwave
12866 | Dalton Trans., 2012, 41, 12865–12871
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Table 2 Electrochemical properties of porphyrins and complexesa
Reduction potential (V) (ΔEp (mV))
Oxidation potential (V) (ΔEp (mV))
Compound
Ered3
Ered2
Ered1
Eox1
Eox2
Eox1 − Ered1
P1
−1.65 (120)
−1.63 (80)
−1.60 (70)
n.d.
−1.86 (90)
−1.96 (110)
−1.35 (120)
−1.26 (80)
−1.30 (60)
−1.42 (100)
−1.49 (140)
−1.59 (90)
0.50 (70)
0.60 (80)
0.51 (100)
0.08 (90)
0.08 (70)
0.02 (80)
0.73 (90)
0.95 (90)
1.85
1.86
1.81
1.50
1.57
1.61
P228
P3
0.77 (110)
C1
C2
C3
n.d.
−2.07 (90)
−2.08 (90)
0.62 (irr.)b,c
0.57 (100)c
0.38 (irr.) 0.45 (80)
a Cyclic voltammetry performed in THF–t-Bu4N(PF6) (0.1 M). All potentials are given vs. Fc+/Fc. One-electron processes in all cases except when
otherwise stated. b For an irreversible process the value stands for Epa. c Two-electron process.
Fig. 3 Absorption spectra of porphyrins in acetonitrile.
Fig. 5 Absorption spectra of P2 and C2.
Fig. 4 Absorption spectra of P1 and C1.
Fig. 6 Absorption spectra of P3 and C3.
2. Characterization
and 96.4 × 103 L mol−1 cm−1. The presence of zinc also
induced a red shift of the Soret compared to P1 (Δλ = 12 nm).
In the Q band region, P2 and P3 did not exhibit the 710 nm
band observed for P1. The Q bands for P3 were also signifi-
cantly red-shifted compared to P2.
The UV-vis spectra of complexes C1, C2 and C3 (Fig. 4–7)
clearly showed important modifications of the electronic proper-
ties of porphyrins P1–P3. In all cases the complexes absorbed
light from the UV to the near infrared.
2.1. UV-vis spectroscopy. The absorption spectra of porphy-
rins are given in Fig. 3. As shown, all porphyrins exhibit the
expected Soret (400–500 nm) and Q bands (550–720 nm). Two
bands were also observed in the 350–400 nm region and are
found to be relatively intense for the free base P1 and zinc por-
phyrin P3 while much weaker in the case of P2.
These bands are attributable to π–π* transitions in the aromatic
ketone part. The coordination by zinc or nickel had different
effects on the ε values of the Soret band that varied in the order
P1 > P3 > P2 with respective values of 104.8 × 103, 100.5 × 103
In particular, the 500–600 nm range, where the parent por-
phyrins did not absorb, was covered upon coordination with
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ruthenium coordination at the periphery of the porphyrins.
Indeed the first oxidation potentials that remained reversible
dramatically dropped to low values 0.02–0.08 V vs. 0.51–0.60 V
for porphyrins. A second oxidation wave was also obtained
where two electrons were exchanged corresponding to overlap-
ping of porphyrin and RuII/RuIII oxidation steps for C1 and C2,
whereas two separated oxidation waves were observed for C3.
The first one was irreversible and may correspond to RuII/RuIII,
the second one is attributed to a second oxidation of the
porphyrin ligand. Three one-electron reduction waves were
detected, except in the case of complex C1. The first and last
reductions were porphyrin-centered while the second was bipyri-
dine ligand-based. The reduction potentials were generally found
to be more negative on going from porphyrins to complexes
with a notable decrease from P3 to C3 (ΔE1/2 red1 = 0.33 V). The
electrochemical band gap Eox1 − Ered1 was substantially lower
for the complexes than for the porphyrins (e.g. 1.57 V for C2 vs.
1.86 V for P228) in agreement with the bathochromic effect
observed from coordination of ruthenium.
Fig. 7 Comparative electronic absorption spectra of dyads C1, C2
and C3.
ruthenium. The absorption bands arise from dπRu−π*bpy MLCT
transitions. This band was red-shifted for C1. The presence of
the Ru(bpy)2 moiety was also confirmed by an intense band
centred at 292 nm due to π–π* bpy transitions.
By comparison with the parent porphyrins, the intensities of
the Soret band were considerably lowered in the complexes
ranging in the C1 > C2 > C3 order. All the Soret bands were
also notably blue-shifted especially for C2 (Δλ = 20 nm) signing
an electronic perturbation of the porphyrin π-system.
2.3 Computational results
The nature of the excited states for P2 and C2 was analyzed by
means of Natural Transition Orbitals (NTOs),38 in particular to
clearly assess the communication between the two subsystems
and the extension of the antenna effect of the porphyrin unit on
the Ru properties (Table 3). For clarity, we remind the reader that
NTOs are obtained by singular value decomposition (SVD) of
the transition density matrix, and they can be considered as the
As expected the four-coordinate Ni–porphyrin P2 and corres-
ponding complex C2 were not found to be emissive due to the
known deactivation of the π–π* excited state via the low energy
(d,d) excited state. The porphyrins P1 and P3 were found to be
emissive and showed an emission band at 726 nm and 713 nm
respectively whatever the excitation wavelength (excitation in
the Soret or Q bands). In complex C1, irradiation at 438 nm
(Soret band) or at 536 nm (MLCT) clearly excited both the por-
phyrin and Rubpy chromophores, as shown by two intense
Table 3 NTOs isodensity surface for main transitions in P2 and C2
Compound λ (nm) Occupied
Virtual
P2
609
3
bands at 674 and 712 nm. The former is attributable to MLCT
excitation while the latter is related to Q-band fluorescence.
Indeed the emission band at 712 nm was the only one generated
upon excitation at 671 nm (Q-band). The emission spectrum of
C3 was found to be different. Upon excitation of the Soret band
(451 nm), three emission bands were obtained at 580, 637 and
707 nm that can be assigned respectively to the excited S1 state
452
3
of porphyrin, MLCT excitation and Q-band fluorescence. Inter-
estingly, only the band at 580 nm remained upon excitation of
the MLCT (516 nm). No emission was detected when the solu-
tion was irradiated at 682 or 765 nm (Q bands). From these
results it appeared that the singlet excited S1 state of the zinc
porphyrin moiety is very close to the excited 3MLCT state of the
ruthenium complexes.
C2
630
525
445
2.2 Electrochemistry
Cyclic voltammetry of porphyrins showed two well-defined
reversible oxidation and reduction waves with one electron
exchanged in each step. The oxidation potentials of P1 and P3
were found to be lower than those of P228 (0.5, 0.51 and 0.60
respectively) while reduction potentials remained almost con-
stant. The voltammograms of complexes revealed the effect of
12868 | Dalton Trans., 2012, 41, 12865–12871
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optimal orbitals to represent an electronic transition in the
TDDFT formalism. In contrast with the Kohn–Sham molecular
orbitals base, that requires many occupied/virtual orbital couples,
in an NTO base only one or at maximum two couples entirely
describe all the physics underlining the transition. Therefore,
“occupied” NTO can be seen as the “hole” orbital, i.e. the orbital
from which an electron is removed during transition, while
“virtual” NTO is the orbital in which an electron is placed in the
excited state.
reagents were used as received. Porphyrins P1 and P2 were pre-
pared according to published procedures.27 Microwave synthesis
was performed on a CEM Discover device fitted with infrared
1
probe temperature control. H and 13C NMR spectra were per-
formed on AC200, AC250, or DRX400 Bruker spectrometers at
ambient temperature. The chemical shifts (δ) were calibrated by
using either tetramethylsilane (TMS) or signals from the residual
protons of the deuterated solvents, and are reported in parts per
million (ppm) from low- to high-field. High-resolution mass
spectrometry (HRMS) data were obtained on a Bruker micrO-
TOF-Q spectrometer. UV-vis spectra were recorded in a 1 cm
path length quartz cell on a LAMBDA 1050 (Perkin Elmer)
spectrophotometer. Emission and excitation spectra were
obtained on optically diluted solutions by using a Fluoromax 2
(Jobin Yvon) Spectrofluorometer. Cyclic voltammetry was per-
formed on a Radiometer PST006 potentiostat using a conven-
tional three-electrode cell. The potassium chloride calomel
electrode (SCE) was separated from the test compartment using
a bridge tube. The test solution was either in methylenechloride
(in the case of P1–P3) or in tetrahydrofuran (in the case of C1–
C3) containing 0.1 M tetrabutylammonium hexafluorophosphate
as a supporting electrolyte. The working electrode was a 10 mm
Pt wire and the counter-electrode a 1 cm2 vitreous carbon disc.
The solutions were purged with argon before each measurement.
A 0.5 mM solution of the studied compound was generally used.
All potentials were quoted versus SCE. Under these conditions
the redox potential of the couple Fc+/Fc was found at 0.50 V vs.
SCE in THF and at 0.42V vs. SCE in CH2Cl2. In all the experi-
The transitions involving P2 expectedly showed that the
Q band transition (609 nm) exhibits a π–π* nature extended to
all the conjugated systems. An important participation of the
region of the enaminoketone can be its efficient conjugation with
the porphyrin crown. The same observation can be made for the
Soret band transition (452 nm) with, in addition, a more impor-
tant participation of the coordinating nickel in the occupied
orbital. The communication between the two units was clearly
evidenced by the NTOs of C2. The lowest energy transition
shows a strong participation of the Ru atom in the occupied
orbital and of the enaminoketone unit in the virtual one. Interest-
ingly, the transition occurring at about 525 nm showed a strong
participation of ruthenium in the occupied orbital while the
virtual one revealed a localisation of the excited electron into the
porphyrin. Thus, this transition can be classified as a Ru to por-
phyrin transition. The NTOs corresponding to the 445 nm
transition clearly evidenced a transition from the porphyrin
(similar to a characteristic Soret band) resulting in a strong
electronic density accumulation on the bipyridine. Note that this
charge redistribution is extremely important in the framework of
DSSC solar cells, since the dyad could be grafted to the semi-
conductor surface via a (functionalized) bipyridine unit and thus
favour injection into the semiconductor conduction band.
ments the scan rate was 100 mV s−1
.
X-Ray diffraction data collection was carried out on a Bruker
APEX II DUO Kappa-CCD diffractometer equipped with an
Oxford Cryosystem liquid N2 device, using Mo-Kα radiation
(λ = 0.71073 Å). The crystal–detector distance was 38 mm.
The cell parameters were determined (APEX2 software)39
from reflections taken from three sets of 12 frames, each at 10 s
exposure. The structure was solved by direct methods using the
program SHELXS-97.40 The refinement and all further calcu-
lations were carried out using SHELXL-97.41 The H-atoms were
included in calculated positions and treated as riding atoms
using SHELXL default parameters. The non-H atoms were
refined anisotropically, using weighted full-matrix least-squares
on F2. A semi-empirical absorption correction was applied using
Conclusions
New dyads have been obtained by the reaction of Ru(bpy)2Cl2
with porphyrins bearing enaminoketones at their periphery.
Communication between the ruthenium and the porphyrin sub-
unit was clearly evidenced by absorption spectra that showed
wide absorption domains. The coordination of ruthenium to
the porphyrins induced a blue shift of the Soret band maxima
as well as a decrease of its intensity while new absorption
appeared in the 500–600 nm range due to the MLCT transition
(dπRu–π*bpy). Electronic communication was also measured by
the electrochemical band gaps (Eox1 − Ered1) that was consider-
ably decreased by ca. 300 mV on going from parent porphyrins
to complexes. Quantum chemical calculations also evidenced an
efficient electronic transfer between the porphyrin and the ruthe-
nium part. From these first results it appears that the porphyrin
can be used as a light harvesting antenna for ruthenium polypyri-
dine complexes. Work is in progress for designing dyes from the
new dyads and investigation in DSSC.
SADABS in APEX2 [5]; transmission factors: Tmin/Tmax
=
0.8683/0.9309.
All quantum chemistry calculations have been performed
using the Gaussian09 B.01 code.42 The geometry for all the
systems, porphyrin and dyads, has been fully optimized at the
DFT level. For geometry optimization the double-ζ quality basis
set LANL2DZ43 has been used throughout. Excited states have
been obtained at the TD-DFT level and their nature has been
analyzed using Natural Transition Orbitals (NTOs) formalism.
NTOs have been obtained by a suitable post-processing of a
Gaussian file realized with Nancy-EX,34 a GPL code written in
our laboratory and freely distributed (see http://sourceforge.net/
projects/nancyex).
Experimental
Materials and methods
Synthesis of porphyrin P3. To a solution of P1 (6.5 mg,
0.01 mmol) in CHCl3 (3 mL) was added a saturated solution of
Zn(OAc)2 in methanol (1 mL) and the mixture was refluxed for
All reactions were conducted under an argon atmosphere. Sol-
vents were distilled before use. All commercially available
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10 min. The mixture was then filtered and the solid was washed
with MeOH. The dark green powder was then dried under
vacuum yielding P3 (6.8 mg, 94%) that was used without
further purification. 1H NMR (400 MHz, DMF-d7), δ (ppm):
9.41 (d, J = 4.6 Hz, 1H), 9.12 (br s, 1H), 8.73 (d, J = 7.9 Hz,
1H), 8.63 (d, J = 5.0 Hz, 1H), 8.61 (dd, J = 5.1 and 1.7 Hz, 1H),
8.58 (d, J = 4.2 Hz, 1H), 8.51 (t, J = 5.1 Hz, 1H), 8.23 (d, J =
4.2 Hz, 1H), 8.2 (m, 6H), 7.98 (m, 4H), 7.83 (m, 6H), 7.65
(t, J = 7.4 Hz, 1H), 5.67 (s, 1H). LRMS (MALDI-TOF): calcd
for C45H27N5OZn m/z = 717.15, found: 717.26 (M+). HRMS
(ESI): calcd for C45H27N5OZn m/z = 717.150, found: 740 129
(M + Na+). UV-vis (CH2Cl2), λmax (nm) (ε (103 M−1 cm−1)) =
470 (100.5), 615 (10.9), 667 (17.5).
for C65H42N9OZnRu m/z = 1130.18, found: 1130.33. HRMS
(ESI): calcd for C65H42N9OZnRu m/z = 1130.185, found:
1130.189. UV-vis (CH3CN), λmax (nm) (ε (103 M−1 cm−1)) =
292 (39.6), 353 (18.8), 393 (19.3), 451 (28.9), 516 (53.8), 682
(7.8), 765 (6.0).
Acknowledgements
The authors are grateful to the CNRS and the Universities
of Lorraine and Strasbourg for their continuous financial
support.
The authors would like to thank also Lydia Brelot and
Corinne Bailly (Service de Radiocrystallographie, UDS) for
solving the X-ray structure, Brigitte Fernette (NMR, UDL),
Stéphane Parant (UV-Vis, UDL) and François Dupire (Mass,
UDL) for their helpful measurements.
Synthesis of complex C1. P1 (6.5 mg, 0.01 mmol) and
Ru(DMSO)4Cl2 (4.8 mg, 0.01 mmol) were dissolved in DMF
(5 mL). The solution was then irradiated in the microwave oven
(200 W, reflux) for 20 min. After the solution was allowed to
cool down to room temperature, DMF (5 mL) and 2,2′-bipyri-
dine (3.1 mg, 0.02 mmol) were added. This solution was again
irradiated in the microwave oven (200 W, 160 °C, 20 min). To
this solution was added a saturated aqueous solution of potass-
ium hexafluorophosphate. The precipitate was washed with
CH2Cl2. Afterward the solid was dissolved in acetone and
poured on a silica gel column. Unreacted P1 was first eluted
using acetone. C1 was next obtained by using an acetone–H2O–
sat. KNO3 (10 : 1 : 1) mixture as an eluent. After half of the
eluent was removed under vacuum, a saturated aqueous solution
of potassium hexafluorophosphate was added. After 12 h, the
dark red precipitate was filtered, washed with water and dried
under vacuum yielding C1 (3.5 mg, 26%).
Due to fast exchange of protons in the porphyrin core, the
NMR spectrum was found to be highly complex and could
not be described accurately. LRMS (MALDI-TOF): calcd
for C65H44N9ORu m/z = 1068.27, found: 1068.41 (M+).
HRMS (ESI): calcd for C65H44N9ORu m/z = 1068.272, found:
1068.272 (M+). UV-vis (CH3CN), λmax (nm) (ε (103
M−1 cm−1)) = 293 (38.3), 438 (54.5), 536 (20.7), 578 (16.8),
671 (6.9).
Notes and references
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4 B. Meunier, Chem. Rev., 1992, 92, 1411–1456.
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J.-P. Gisselbrecht and R. Ruppert, in The Handbook of Porphyrin
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Synthesis of complex C2. The procedure used for C1 was
repeated using P2 (7.1 mg, 0.01 mmol) yielding C2 (3.2 mg,
22%) as a brown solid. 1H NMR (400 MHz, acetonitrile-d3),
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8.70 (d, J = 5.2 Hz, 1H), 8.55–8.40 (m, 5H), 8.31 (d, J =
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1H). HRMS (ESI): calcd for C65H42N9ONiRu m/z
=
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12870 | Dalton Trans., 2012, 41, 12865–12871
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Dalton Trans., 2012, 41, 12865–12871 | 12871