Photoinduced electron transfer in supramolecular ruthenium-porphyrin assemblies

Article abstract of DOI:10.1039/c6dt04414j

We present dynamic supramolecular systems composed of a Ru(ii) complex of the form of [Ru(dtBubpy)₂(qpy)][PF₆]₂ (where dtBubpy is 4,4′-di-tert-butyl-2,2′-dipyridyl and qpy is 4,4′:2′,2′′:4′′,4′′′-quaterpyridine) and zinc t

Full text of DOI:10.1039/c6dt04414j

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Photoinduced Electron Transfer in Supramolecular
RutheniumꢀPorphyrin Assemblies.
Diego Rota Martir,a Mattia Averardi,a Daniel Escudero,b Denis Jacquemin b,c and Eli
Zysman-Colmana*
a Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St
Andrews, St Andrews, Fife, KY16 9ST, UK, Fax: +44ꢀ1334 463808; Tel: +44ꢀ1334 463826;
Eꢀmail: eli.zysmanꢀcolman@stꢀandrews.ac.uk;
URL: http://www.zysmanꢀcolman.com
b
CEISAM UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208,
44322 Nantes Cedex 3, France
c Institut Universitaire de France, 1, rue Descartes, 75005 Paris Cedex 5, France
Abstract. We present dynamic supramolecular systems composed of a Ru(II) complex of the
form of [Ru(dtBubpy)2(qpy)][PF6]2 (where dtBubpy is 4,4′ꢀdiꢀtertꢀbutylꢀ2,2′ꢀdipyridyl and
qpy is 4,4':2',2'':4'',4'''ꢀquaterpyridine) and zinc tetraphenylporphyrins (ZnTPP), through nonꢀ
covalent interactions between the distal pyridine moieties of the qpy ligand the zinc of
ZnTPP. The optoelectronic properties of the assemblies and the electronic interactions
between the chromophoric units have been comprehensively characterized by computational
investigations, and steadyꢀstate and timeꢀresolved emission spectroscopy. Upon
photoexcitation of ZnTPP, electron transfer to the ruthenium center is thermodynamically
favorable and, as a result, strong emission quenching of both units occurs.
Introduction.
Multiꢀchromophoric donorꢀacceptor systems composed of wellꢀdefined
photophysicallyꢀactive units have served as surrogates to probe the nature of the
photoinduced energy transfer (PET) and electron transfer (PeT) processes found in natural
photosynthetic organisms. These same systems are also of great interest as dyes in solar
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energy conversion applications.1 Many of these artificial systems are formed by combining
metalloꢀporphyrins with others photoꢀ and redoxꢀactive species, such as Ru, Ir or Re
complexes and, following this approach, a wide array of multiꢀcomponent assemblies has
been explored to mimic the lightꢀharvesting exhibited by photosynthetic organisms.2
However, in most of these cases the complexes are covalently connected along the porphyrin
plane and, surprisingly, little is still known about their electronic communications upon nonꢀ
covalent axial coordination to the porphyrin.3
We recently reported dynamic [Ir]…[ZnTPP] and [Ir]…[ZnTPP]2 dyad and triad
systems, Figure 1a, composed of
a
cationic iridium complex of the form
[Ir(dFppymes)2(qpy)]PF6 (where dFppymes is 2ꢀ(4,6ꢀdifluorophenyl)ꢀ4ꢀmesitylpyridinato and
4
qpy is 4,4':2',2'':4'',4'''ꢀquaterpyridine) and zinc tetraphenylporphyrin, ZnTPP. We showed
that in these systems only selfꢀabsorption occurs between the [Ir] donor and ZnTPP acceptor.4
PeT from [Ir] to ZnTPP is not thermodynamically favorable while PeT from ZnTPP to [Ir]
was found to be exergonic (ꢁGCS = ꢀ0.68 V); however there was no experimental evidence to
support the formation of the chargeꢀseparated [ZnTPP]+ꢀ[Ir]ꢀ state. One possible explanation
of this facts is that the PeT process might not be fast enough to compete with the other
deactivation processes.
By contrast, when zinc tetratolylporphyrin (ZnTPP) is either covalently or nonꢀ
covalently connected to a ruthenium(II) trisꢀbipyridyl complex (Figure 1b), PeT from ZnTPP
to the ruthenium center is experimentally observed at an ultrafast time scale (< 100 ps).5
Many other examples of systems composed of metalloꢀporphyrins and ruthenium(II)
polypyridine conjugates have been investigated.6 In these systems, as a result of the
formation of chargeꢀseparated state following PeT from the porphyrin units to the ruthenium
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moieties, the phosphorescence of the ruthenium complexes is quenched and only weak
porphyrinꢀcentered luminescence is generally detected.
Figure 1. a) Schematic representation of the absence of electron transfer in the
supramolecular iridiumꢀzinc assemblies.4 b) Schematic representation of PeT observed in the
rutheniumꢀzinc assembly.5a
With this in mind, we report the selfꢀassembly and the photophysical investigation of
analogous systems to those reported in Figure 1a, based on nonꢀcovalent axial coordination
between ZnTPP as the donor unit and the ruthenium complex [Ru(dtBubpy)2(qpy)]2PF6
(where dtBubpy is 4,4'ꢀdiꢀtertꢀbutylꢀ2,2'ꢀbipyridine) as the acceptor moiety (Charts 1 and 2).
These multiꢀchromophoric systems are of particular interest as models of supramolecular
dyes used in artificial photosynthesis and photoelectrochemical devices. In particular, the
subsequent replacement of the dtBubpy ligands in 1 with dcbpy (2,2’ꢀbipyridineꢀ4,4’ꢀ
dicarboxylic acid) ligands would allow us to transfer this fundamental study of the electronic
communication between the ruthenium complex and ZnTPP directly into a DSSC
application.7 This design contributes to an improved absorption profile and therefore
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enhanced short circuit current by combining the absorption profiles of both ZnTPP and the
ruthenium complex.2c, 8
We also prepared [Ru(dtBubpy)3][PF6]2, 2, as a negative control molecule in the form
of the “nonꢀassembly 2a” (Chart 2b) to verify the presence/absence of electronic
communication between 1 and ZnTPP as a result of axial coordination to Zn.
Chart 1. Chemical structures of the reference mononuclear Ru(II) complexes 1 and 2 and
ZnTPP under investigation in this work.
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Chart 2. a) Chemical structures of the assemblies 1a [Ru(dtBubpy)2(qpy)][PF6]2 : ZnTPP 1:1
ratio and 1b [Ru(dtBubpy)2(qpy)][PF6]2: ZnTPP 1:2 ratio. b) Chemical structure of complex
2 mixed with ZnTPP (2a).
Results and Discussion
Self-assembly investigation by 1H NMR spectroscopy.
The assemblies 1a and 1b were rapidly obtained after mixing 1 with one or two
equivalents of ZnTPP, respectively, in CD2Cl2 at room temperature. The four tertꢀbutyl
moieties present in 1 conferred the requisite solubility in CD2Cl2, a solvent chosen to not
interfere with the axial coordination of the distal pyridines present in 1 with ZnTPP. The
1
formation of the assemblies was monitored by H NMR, 2D COSY, HMBC and HMQC
spectroscopies (1H NMR, 2D COSY, HMBC and HMQC spectra are reported in the SI).
1H NMR titration experiments of ZnTPP (from 0.1 to 2.5 equivalents, ranging from 0
to 9.44 mM) into a 3.06 mM solution of 1 in CD2Cl2 results in a broadening and gradual upꢀ
field shift of the proton resonances associated with 1 (Figure 2). As expected, due to the axial
coordination of the pyridine ring to ZnTPP, the proton resonances associated with the qpy
moiety (Ha, Hb, Hc, Hd in Figure 2) were shifted the most upꢀfield. The 1H NMR titration data
1
extracted from the chemical shift of the resonance of Ha (Figure S13, from δ 8.77 to δ 7.84
ppm) could be fitted to a sequential binding model (Figure S14a) affording equilibrium
constants of 7200 ± 300 M–1 for the formation of 1a from 1 and ZnTPP and 2500 ± 350 M–1
for the formation of 1b from 1a and ZnTPP. Speciation plots for the formation of 1a and 1b
as a function of the initial concentration and stoichiometry of the mixture have been
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determined (Figure S14b,c). For solutions containing 1:1 mixture of 1 and ZnTPP, 1a is the
dominant complex at all concentrations between 100 µM and 100 mM. For solutions
containing a 1:2 mixture of 1 and ZnTPP, 1a is the dominant complex at concentrations
below 600 µM and 1b is the dominant complex between this concentration and 100 mM.
1
Figure 2. H NMR spectra in CD2Cl2, 500 MHz at 298 K. The concentration of 1 was kept
1
1
constant at 3.06 mM. a) H NMR spectrum of 1; b) H NMR spectrum of the assembly 1a,
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1
[ZnTPP] = 3.06 mM; c) H NMR spectrum of the assembly 1b, [ZnTPP] = 6.12 mM; d)
chemical structures of 1a and 1b. The assignments correspond to the labelling shown in d).
1
As illustrated in Figure 2b, the H NMR spectrum for 1a is relatively simple,
indicating local C2 symmetry around the ruthenium centre. This observation suggests that the
exchange of bound and unbound ZnTPP is fast on the NMR timescale and that the 1H NMR
spectrum observed reflects a mixed speciation of ZnTPP – both free ZnTPP and ZnTPP
bound to 1. When 1 and ZnTPP are mixed in a 1:1 ratio at a concentration of 3.06 mM (NMR
spectrum shown in Figure 2b), a speciation of 1:1a:1b = 0.04:1:0.1 is present, whereas when
a second equivalent of ZnTPP is added (NMR spectrum shown in Figure 2c), a speciation of
1:1a:1b = 0.03:0.3:1 is obtained.9 As expected, the association constants obtained for the
assemblies 1a and 1b are very close to the values reported for the analogous assemblies
illustrated in Figure 1 and similar to the values reported for the coordination between other
Nꢀdonor ligands and ZnTPP, ranging from Ka = 102 to 105 M–1.3b Expectedly, when 2 was
1
mixed with two equivalents of ZnTPP no change was observed in the H NMR spectra
(Figure S15).
Optoelectronic properties.
Absorption.
The optoelectronic properties of ZnTPP, 1, 1a, 1b, 2 and 2a have been investigated in
DCM solutions at room temperature and the results are summarized in Table S1. The UVꢀ
visible absorption spectra of 1 and 2 (Figure 3) are both characterized by an intense band at
ca. 285 nm assigned to a spinꢀallowed ligandꢀcentered π−π∗ transition localized on the
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dtBubpy ligand and a broad band in the visible region, at ca. 440 nm and 494 nm for 1 and at
ca. 432 and 469 nm for 2. These transitions are assigned to the typical metalꢀtoꢀligand charge
transfer transition (1MLCT) to the dtBubpy ligand for 2 whereas, as theoretically predicted,
1
the MLCT bands for 1 involve both the dtBubpy and the quaterpyridine ligands.10 Indeed,
timeꢀdependent density functional theory (TDꢀDFT) calculations on complex 1 corroborate
the nature of the main UVꢀVis bands (see Table S3 in the ESI). The CT absorption of 1 is
redꢀshifted (λmax = 439 nm and 493 nm) compared to 2 (λmax = 434 nm and 465 nm) due to
the enhanced conjugation present in the qpy ligand.10c, 11 The absorption spectra of 1:1 and
1:2 ratios of 1 and ZnTPP at 10ꢀ6 M where less than 1% of ZnTPP is bound to 1, show the
expected superposition of the respective absorption spectra of the two complexes (Figure 3).
Figure 3. UVꢀVis spectra of [Ru(dtBubpy)2(qpy)]2PF6 (1, in solid blue line),
[Ru(dtBubpy)3]2PF6 (2, in solid red line), ZnTPP (dashed lightꢀgreen line) and 1 : ZnTPP =
1:1 (1a, dashed green line) collected in CD2Cl2 at 298 K with a concentration on the order of
10–6 M.
8

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Electrochemical properties.
The groundꢀstate electronic communication between [Ru] and ZnTPP in 1a and 1b
has been investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV)
in deaerated DCM solution at a concentration of 1.24 x 10ꢀ3 M, a concentration where ZnTPP
is completely bound to 1 and where 1, 1a and 2a, are present in a ratio of 1:1a:1b =
0.02:0.1:1 when 1 and ZnTPP are mixed in a 1:1 ratio and 1:1a:1b = 0.02:1:1.6 when a
second equivalent of ZnTPP is added.12 Similarly to the CVs of other cationic ruthenium
complexes,10b, 13 1 and 2 exhibit a oneꢀelectron reversible oxidation wave at, respectively,
Eox1/2 = 1.43 V and Eox1/2 = 1.37 V attributed to the RuII/RuIII redox couple (Figure S18). The
presence of the two addition tertꢀbutyl groups in 2 detabilizes the oxidation compared to 1
while the distal pyridines on the qpy ligand inductively withdraw electron density leading to
an anodic shift of the oxidation wave relative to 2.10c Two quasiꢀreversible oneꢀelectron
reduction waves at Ered = ꢀ1.04 V and Ered = ꢀ1.51 V localized on the quaterpyridine
1/2
1/2
ligands are observed for 1. A single oneꢀelectron reversible reduction at Ered = ꢀ1.24 V
1/2
localized on one of the dtBubpy ligands is observed for complex 2. These redox processes are
also observed in the DPV spectra illustrated in Figure S18 and in Figure S20 for complex 1
and 2, respectively.
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Figure 4. CVs reported versus SCE for ZnTPP, 1a, 1b and 1 recorded at 298 K in deaerated
DCM solution containing n-NBu4PF6 as the supporting electrolyte and using Fc/Fc+ as an
internal standard (Fc/Fc+ = 0.46 V in DCM with respect to SCE).14
For the assemblies 1a and 1b the oxidation potentials localized on the ruthenium
complex are slightly cathodically shifted to lower potentials compared to 1 (Epa = 1.43 V for
1 vs. Eox = 1.35 V for 1a and Eox = 1.26 V for 1b, Figure 4). However, similar to the
1/2
1/2
iridiumꢀZnTPP assemblies that we previously studied,4 upon ZnTPP coordination with the
distal pyridine moieties of 1,15 the porphyrinꢀcentered oxidation waves of both 1a and 1b are
significantly cathodically shifted (Eox = 0.71 V for 1a, Eox = 0.66 V for 1b vs. Eox
=
1/2
1/2
1/2
0.86 V for ZnTPP) while their first reduction processes are likewise cathodically shifted
(Ered = –1.52 V for 1a, Ered = –1.55 V for 1b vs. Epc = –1.37 V for ZnTPP). In addition,
1/2
1/2
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an extra wave at around 1.52 V and 1.47 V can be observed respectively in the CVs of 1a
and 1b, which are assigned to the oxidation of uncomplexed 1. The CVs of 2 and of the “nonꢀ
assembly” 2a were also investigated in deareated DCM as a control system and, as expected,
the CV 2a contains only the superposition of the redox processes of 2 and ZnTPP, with no
groundꢀstate electronic communication between the two units (Figure S19 and S20).
Prediction of photoinduced electron transfer processes.
The redox potentials and optical data were used to estimate the energetics of the
electron transfer processes exhibited by the compounds under investigation.
Figure 5a shows the lowest excited tripletꢀstate energy of 1 and the lowest excited
singletꢀstate energy of ZnTPP (E0,0 energies) estimated from the intersection point between
their respective absorption and luminescence spectra collected in DCM at room temperature
(see below). Figure 5b represents the inferred energies of oxidation and reduction potentials
of 1 and ZnTPP obtained by CV analysis. The E0,0 energies and the redox potentials of
ZnTPP, 1, 2 and the assemblies 1a and 1b are reported in Table 1.
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Figure 5. a) Representation of the energy of the zeroꢀzero transition (E0,0) to the lowest
excited state of complex 1 and ZnTPP obtained by spectroscopic analysis. As the energy of
the lowest triplet state of ZnTPP (3ZnTPP*) we used the value previously reported.16 b)
Representation of the energies of the first oxidation and first reduction waves, the associated
redox gap and oxidation and reduction potentials of complex 1 and ZnTPP obtained by
electrochemical analysis of ZnTPP and 1. EHOMO = ꢀ(Eox
+ 5.39) eV, ELUMO = ꢀ
pa vs Fc/Fc+
(Eredpc vs Fc/Fc+ + 5.39) eV.17
The oxidation and reduction potentials of ZnTPP are located at ꢀ6.3 and ꢀ4.0 eV,
respectively whereas for 1, both these levels are stabilized at ꢀ6.8 and ꢀ4.4 eV. Therefore, for
1a and 1b, ZnTPP acts as the electronꢀdonor unit while 1 acts as the electronꢀacceptor
moiety.18
The free energy (ꢁGCS) associated with the formation of the chargeꢀseparated state
[ZnTPP]+[Ru]ꢀ can be easily calculated following the RehmꢀWeller equation (1),18a, 19
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⋅+
⋅−


ꢀGCS = e E (D / D*)− E (A*/A ) − E +Gs
(1)
1/2
1/2
0,0


⋅+
⋅−


for 1a and 1b are nearly
e E (D / D*)− E (A*/A )
The excited state redox gap
1/2
1/2


identical at, respectively, 1.69 and 1.68 eV. The ionꢀpair stabilization energy, Gs, for both 1a
and 1b was inferred to be ꢀ0.14 eV and E0,0 for the donor was determined to be 2.24 eV.9
Consequently, following photoexcitation of 1a and 1b, electron transfer from ZnTPP to
complex 1 is found to be exergonic in DCM (ꢁGCS = –0.56 eV for 1a and 1b). In addition,
the kinetic of the process may also play an important role for the activation of the PeT.20 By
contrast, ꢁGCS = + 0.74 eV for the formation of the chargeꢀseparated state [Ru]+[ZnTPP]ꢀ so
is not a thermodynamically favorable process.
Table 1. Electrochemical data and E0,0 values.
a
a
a
a
a
d
e
Complex
Eox
Eox
Eox
Ered
Ered
Egap
E0,0
/ V
/ V
1.25b
ꢀ
/ V
ꢀ
/ V
/ V
–1.79c
–1.51b
ꢀ
/ V
2.23
2.47
2.61
1.84
1.80
2.20
/ eV
2.19
2.08e
2.29
2.20
2.20
2.24
0.86b
1.43b
1.37b
0.71b
0.66b
0.84c
ꢀ1.37c
–1.04b
–1.24c
–1.13b
–1.14b
–1.36b
ZnTPP
ꢀ
1
ꢀ
ꢀ
2
1.12b
1.05b
1.22b
1.35b
1.26b
1.37b
–1.63c
–1.64c
ꢀ
1a
1b
2a
aCV traces recorded in DCM solution with 0.1 M (n-Bu4N)PF6 at 298 K at 50 mV.sꢀ1. Values
are in V vs. SCE (Fc/Fc+vs. SCE = 0.46 V).14 bE1/2 = (Epa + Epc)/2 and result from oneꢀelectron
processes. cIrreversible oxidation and reduction peak potentials, Epa reported for oxidation and
Epc reported for reduction. dCalculated from Eox – Ered where Eox is the first oxidation potential
and Ered is the first reduction potential.eE0,0 determined from the intersection point of the
absorption and emission spectra at 298 K in DCM.
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Emission Studies.
Emission studies were carried out in DCM solution at a concentration of 3 × 10ꢀ4 M
in order to verify experimentally the presence of PeT in 1a and 1b. At this concentration
ZnTPP is completely bound to the ruthenium complex with a ratio of 1:1a:1b = 0.01:1:0.01
when 1 is mixed with 1 equivalent of ZnTPP and with a ratio of 1:1a:1b = 0.01:1.2:1 when a
second equivalent of ZnTPP is added.9 Upon photoexcitation of 1 and 2 into either their CT
or LC absorption bands (at around 500 or 400 nm, respectively), broad and unstructured
emissions from the 3MLCT state at, respectively, 672 nm and 615 nm are observed (red lines
in Figure 7). Due to increased conjugation present in the qpy ligand, the emission of 1 is redꢀ
shifted compared to 2. As reported in Table S2, the ΦPL for 1 and 2 are similar at 7 and 9%,
respectively. The character of the emissive state was confirmed by a DFT optimization of the
lowest excited tripletꢀstate (T1, (see exemplarily the spin density distribution for 1 in Figure
6a)). When ZnTPP is photoexcited into either the Soret or Q bands (λexc = 420 or 550 nm,
respectively), a characteristic vibronic fluorescence is observed between 570 and 740 nm
(blue lines in Figure 7).4
Emission spectra acquired at different excitation wavelengths during the titration of
one to three equivalents of ZnTPP into a 3 × 10ꢀ4 M solution of 1 to form the assemblies 1a
and 1b are reported in Figure S21 – S23. Upon excitation of 1a and 1b into either the CT
absorption band of [Ru (λexc = 500 nm)], the Qꢀband of ZnTPP (λexc = 550 nm) or the Soret
band of ZnTPP (λexc = 420 nm), resulted in a significant reduction in the ΦPL for ZnTPP
(ΦPL(ZnTPP) = 4%; ΦPL(ZnTPP) < 1% in 1a and 1b, Table S2) while the emission of 1 was
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completely quenched (Figure 7). The efficient quenching of the phosphorescence of 1 and the
fluorescence of ZnTPP are due to the formation of the nonꢀemissive chargeꢀseparated state
[ZnTPP]+[Ru]– as was predicted following the RehmꢀWeller equation and in agreement with
the PeT processes reported for similar systems.5, 21 Indeed, by contrast to 1, the optimization
of its lowest triplet excited state leads to a CT state (see exemplarily for 1a in Figure 6b). The
enhanced nonꢀradiative decay from this darkꢀstate (that eventually leads to the formation of
the chargeꢀseparated states) is responsible of the emission quenching observed in the
assemblies.22
As a result of the strong emission quenching observed for 1a and 1b, no emission
lifetimes could be discerned.
Figure 6. Spinꢀdensity distributions [B3LYP/6ꢀ31G(d) – ecpꢀ28ꢀmwb for Ru] at the
optimized geometry of the lowest triplet excited state of 1 (a) and 1a (b).
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Figure 7. a) Normalized luminescence spectra of 1 (solid red line), ZnTPP (solid blue line),
1a (dotted orange line) and 1b (dotted green line) recorded in degassed DCM at 298 K
(λex = 555 nm) with a concentration in the order of 3 x 10−4 M. b) Normalized luminescence
spectra of 2 (solid red line), ZnTPP (solid blue line) and of the “nonꢀassembly” 2a (dotted
orange line) recorded in degassed DCM at 298 K (λex = 555 nm) with a concentration in the
order of 10−4 M.
To discern whether the formation of the nonꢀemissive chargeꢀseparated state
observed for 1a and 1b is favored through the coordination of ZnTPP to the qpy, emission
spectra were also collected after addition of ZnTPP to the control complex 2 (at a
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concentration of 3 × 10–4 M) where coordination is not possible (the emission spectra are
reported in Figure S24 – S26). We noted that upon excitation at 420, 500 or 550 nm, the
emission of 2 was likewise strongly quenched and presented similar behavior to that observed
for 1a and 1b (Figure 7b). Thus, we attribute the strong emission quenching of both the
ruthenium complex and ZnTPP as the result of longꢀdistance collisional processes between
the two chromophoric units.23
Conclusions.
In conclusion, we report the synthesis and optoelectronic study of [Ru]…[ZnTPP]
dyad and [Ru]…[ZnTPP]2 triad supramolecular assemblies where the ZnTPP is bound to [Ru]
through axial coordination of zinc metal to the distal pyridine moieties of the qpy of
[Ru(dtBubpy)2(qpy)][PF6]2. For the assemblies 1a and 1b, favorable PeT from ZnTPP to [Ru]
is predicted (ꢁGCS = –0.51 eV) and evidence of emission quenching through the formation of
the nonꢀemissive chargeꢀseparated [ZnTPP]+[Ru]ꢀ state was observed. The emission of 2 and
ZnTPP were likewise quenched upon mixing at a concentration of 3
⨉
10ꢀ4 M. Thus, we can
confirm that selfꢀassembly of [Ru] and ZnTPP is not necessary to promote PeT from ZnTPP
to [Ru] under our experimental conditions.
Acknowledgements
EZꢀC acknowledges the University of St Andrews and EPSRC
(EP/M02105X/1) for financial support. We thank the EPSRC UK National Mass
Spectrometry Facility at Swansea University for analytical services. We thank Umicore AG
for the gift of materials. DE thanks funding from the European Union’s Horizon 2020
research and innovation programme under the Marie SklodowskaꢀCurie grant agreement No
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700961. DJ acknowledges the European Research Council (grant: 278845) and the RFI
Lumomat for financial support. This research used resources of (1) the GENCIꢀ
CINES/IDRIS, (2) Centre de Calcul Intensif des Pays de Loire (CCIPL), and (3) a local Troy
cluster.
Supporting Information. Experimental section, characterisation of precursors, ligands,
ruthenium complexes and supramolecular assemblies; solution NMR investigations of the
assemblies; determination of the association constants; absorption and emission studies at
different concentrations, emission studies and electrochemical characterization;
computational details.
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