Electrochemistry and spectroelectrochemistry of bismanganese biscorroles dyads

Article abstract of DOI:10.1142/S1088424611003124

Three manganese biscorrole dyads were synthesized, physicochemically characterized and investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous media. Each dyad contained the same two corroles linked in a face-to-face arrangemen

Full text of DOI:10.1142/S1088424611003124

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2011; 15: 188–196
DOI: 10.1142/S1088424611003124
Published at http://www.worldscinet.com/jpp/
Electrochemistry and spectroelectrochemistry of
bismanganese biscorroles dyads
Ping Chena, Maya El Ojaimia,b, Claude P. Grosb, Jean-Michel Barbe*b,
Roger Guilardb, Jing Shena and Karl M. Kadish*a
a University of Houston, Department of Chemistry, Houston, Texas 77204-5003, USA
b Université de Bourgogne, ICMUB (UMR 5260), 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex, France
Received 8 March 2011
Accepted 21 March 2011
ABSTRACT: Three manganese biscorrole dyads were synthesized, physicochemically characterized and
investigated as to their electrochemistry and spectroelectrochemistry in nonaqueous media. Each dyad
contained the same two corroles linked in a face-to-face arrangement via one of the three different linking
groups, 9,9-dimethylxanthene, anthracene or diphenylether, the exact nature of which determined the
distance and possible interaction between the two metallomacrocycles. The initial compounds contained
Mn(III) in their air stable form and were shown to exhibit two major redox processes, one being a Mn(III)/
Mn(IV) conversion and the other being either Mn(III)/Mn(II) or reduction at the conjugated macrocycle
to give a Mn(III) corrole π-anion radical when the solvent was pyridine. The potentials and reversibility
of each electron transfer reaction were shown to depend upon the solvent (pyridine, CH2Cl2, or PhCN),
type of spacer separating the two macrocycles and/or the presence or absence of axial ligation. The site
of each electron transfer was assigned on the basis of spectroscopic and electrochemical data and by
comparison with reactions and properties of the monocorrole (Mes2PhCor)Mn which was characterized
in a previous publication and also examined in the current study under the same solution conditions as
the newly investigated dyads. Some electrode reactions of the dyads were followed by coupled chemical
reactions and these were also elucidated in the present study.
KEYWORDS: biscorroles, manganese, electrochemistry, ligand binding.
directly related to changes in the extent of π-π interaction
between the two macrocycles and the overall properties
of the compound [17–21].
Our own interest in this area has focused in large part
on homobimetallic and heterobimetallic biscorroles [1,
15, 21] and porphyrin-corrole [16, 22, 23] dyads contain-
ing cobalt, manganese or iron as a central metal, each
of which can exist in both high and low oxidation states
under the application of a specific oxidizing or reducing
potential.
We recently reported how anion and solvent binding
can affect redox potentials and axial ligation of mono-
meric Mn(III) corroles [24] and bimetallic Mn(III)
porphyrin-corrole dyads [25] and now turn our atten-
tion to the electrochemistry, spectroelectrochemistry
and UV-visible properties of three manganese biscorrole
dyads where the two metallomacrocycles are linked in a
INTRODUCTION
Bis-metalloporphyrins linked in a face-to-face (cofa-
cial) arrangement by a “rigid” or “flexible” bridge have
been used as catalysts for many oxidation reactions
[1–10]. These dyads may encapsulate guest molecules
inside the bismacrocycle pocket, with the exact stoichio-
metry depending upon the specific combination of metal
ions, solvent and shape or length of the bridging spacer
[11–16]. Changes in the bridge structure have been used
to control the distance between the two porphyrin units
as well as the degree of opening and closing which is
SPP full and student member in good standing
*Correspondence to: Karl M. Kadish, email: kkadish@uh.edu,
fax: +1 (713)-743-2745 and Jean-Michel Barbe, email: Jean-
Michel.Barbe@u-bourgogne.fr, fax: +33 (0)38-039-6117
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Mass spectra were obtained either with a Bruker
Ultraflex II instrument in MALDI-TOF reflectron mode
using dithranol (1,8-dihydroxy-9[10H]-anthracene) as a
matrix. UV-visible spectra of the synthesized complexes
were recorded in CH2Cl2 on a Varian Cary 50 Scan
spectrophotometer.
Chemicals and reagents
Pyridine (py, 99.8%) was obtained from Sigma-Aldrich
ChemicalCo. andusedwithoutfurtherpurification. Benzo-
nitrile (PhCN) was purchased from Aldrich Chemical Co.
and distilled over P2O5 under vacuum prior to use. Abso-
lute dichloromethane (CH2Cl2, 99.8%) was received from
EMD Chemicals Inc. and used without further purifica-
tion. Tetra-n-butylammonium perchlorate (TBAP, ≥99%)
and tetrabutylammonium acetate (TBAOAc, ≥99%) were
Chart 1. Structures of investigated bis-manganese complexes
purchased from Fluka Chemical Co. and used as received.
Neutral alumina (Merck; usually Brockmann Grade III,
i.e. deactivated with 6% water) or Silica gel (Merck :
70–120 μm) was used for column chromatography. Ana-
lytical thin layer chromatography was performed using
Merck 60 F254 neutral aluminum oxide gel (precoated
sheets, 0.2 mm thick) or Merck 60 F254 silica gel (pre-
coated sheets, 0.2 mm thick). Reactions were monitored
by thin layer chromatography and spectrophotometry.
The free-base biscorroles (BMes2CX)H6, (BMes2CA)H6
and (BMes2CO)H6 were prepared as previously reported
in the literature [15]. Synthesis of the monocorrole
(Mes2PhCor)Mn (1) was carried out as recently reported
[24].
4,5-Bis-[manganese-(5,15-dimesitylcorrol-10-yl)]-
9,9-dimethylxanthene (BMes2CX)Mn2 (2). Under nitro-
gen, a mixture of 286 mg of (BMes2CX)H6 (0.22 mmol,
1 equiv.) and 215 mg of Mn(OAc)2·4H2O (0.88 mmol,
4 equiv.) in 200 mL of 1,2-dichloroethane/methanol/
ethanol (15/2/3) was heated at 85 °C for 24 h in the pres-
ence of sodium acetate (10 equiv.). The reaction mix-
ture was then allowed to cool to room temperature and
washed with water (3 × 75 mL), dried over MgSO4, and
then evaporated. The remaining residue was chromato-
graphed on silica (CH2Cl2/methanol 95/5 as eluent) and
the last fraction was collected to give the title biscorrole
bismanganese complex (2) in 55% (170 mg, 0.12 mmol).
HR-MS (MALDI-TOF): m/z 1378.4514 [M]+•, 1378.4590
calcd. for C89H72Mn2N8O. UV-vis (CH2Cl2): λmax, nm (ε ×
103, M-1.cm-1) 324 (32), 403 (54), 634 (3.5).
face-to-face arrangement with one of the following three
spacers: 9,9-dimethylxanthene (X), anthracenyl (A) or
diphenylether (Ox). Structures of the investigated com-
pounds are shown in Chart 1 where Mes = a mesityl
substituent and the dyads are represented by (BMes2CX)
Mn2 (2), (BMes2CA)Mn2 (3) or (BMes2COx)Mn2 (4) where
X, A or Ox are one of the three named spacer above.
Previous studies of bis-cobalt(III) corrole dyads having
different macrocyclic substituents but the same or similar
spacers have shown that the two macrocycles exhibit an
interaction upon electrooxidation in PhCN [15, 21]. This
differs from what is seen in the current study under the
same solution conditions but an interaction is observed in
CH2Cl2 as described on the following pages.
EXPERIMENTAL
Instrumentation
Cyclic voltammetry was carried out with an EG & G
model 173 potentiostat/galvanostat. A homemade three-
electrode electrochemistry cell was used and consisted
of a platinum button or glassy carbon working electrode,
a platinum wire counter electrode and a saturated calo-
mel reference electrode (SCE). The SCE was separated
from the bulk of the solution by a fritted-glass bridge
of low porosity which contained the solvent/supporting
electrolyte mixture. All potentials are referenced to the
SCE.
UV-visible spectroelectrochemical experiments were
performed with an optically transparent platinum thin-
layer electrode of the type described in the literature
[26]. Potentials were applied with an EG & G Model 173
potentiostat/galvanostat. Time-resolved UV-visible spec-
tra were recorded with a Hewlett Packard Model 8453
diode array rapid-scanning spectrophotometer.
1,8-Bis-[manganese-(5,15-dimesitylcorrol-10-yl)]-
anthracene (BMes2CA)Mn2 (3). This compound was
prepared in 58% yield (141 mg, 0.10 mmol), as described
for (BMes2CX)Mn2, starting from (BMes2CA)H6 (225
mg, 0.18 mmol, 1 equiv.) and Mn(OAc)2·4H2O (177
mg, 0.72 mmol, 4 equiv.). HR-MS (MALDI-TOF): m/z
1346.4343 [M]+•, 1346.4328 calcd. for C88H68Mn2N8.
UV-vis (CH2Cl2): λmax, nm (ε × 103, M-1.cm-1) 312 (27),
405 (42), 634 (5).
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2,2′-Bis-[manganese-(5,15-dimesitylcorrol-10-yl)]-
diphenylether(BMes2COx)Mn2 (4).Thiscompoundwas
prepared in 62% yield (207 mg, 0.15 mmol), as described
for (BMes2CX)Mn2, starting from (BMes2COx)H6 (308
mg, 0.25 mmol, 1 equiv.) and Mn(OAc)2·4H2O (245
mg, 1.00 mmol, 4 equiv.). HR-MS (MALDI-TOF): m/z
1338.4279 [M]+•, 1338.4277 calcd. for C86H68Mn2N8O.
UV-vis (CH2Cl2): λmax, nm (ε × 10-3, M-1.cm-1) 312 (31),
401 (55), 635 (4).
with the proposed structural arrangement, i.e. the bime-
tallic nature of each compound. Moreover, the high reso-
lution and mass accuracy of the instrument along with
a good fit between experimental and calculated ionic
patterns allowed for an unambiguous assignment of the
dyads’ structure.
Electrochemistry and spectroelectrochemistry
Each biscorrole was examined as to its electrochemi-
cal and UV-vis properties after oxidation or reduction in
PhCN, pyridine or CH2Cl2 containing 0.1 M TBAP. The
reduced forms of 2–4 in the non-binding solvent CH2Cl2
were not stable and the current-voltage curves obtained
in this solvent were ill-defined or show several side reac-
tions. In contrast, most reductions of the investigated
dyads were reversible in pyridine and PhCN, indicating
a stabilization of the electroreduced species in these two
higher donor solvents.
RESULTS AND DISCUSSION
Structures of the investigated bis-manganese and
mono-manganese derivatives are given in Chart 1. Each
manganese complex was prepared in good yield starting
from the corresponding free-base biscorrole dyads [15].
UV-visible and mass spectrometry
Cyclic voltammograms of the bismanganese biscor-
roles 2–4 in PhCN and pyridine are presented in Fig. 1
and exhibit electrochemical properties extremely close to
those of the monocorrole 1 which is also shown in Fig. 1
and was recently described in the literature [24]. For
example, in the weakly coordinating PhCN solvent the
monocorrole exhibits two oxidations associated with the
conversion of Mn(III) to Mn(IV), at E1/2 = 0.12 to 0.45 V,
and two reductions associated with the conversion of
UV-visible absorption maxima and molar absorp-
tivities of dyads 2–4 in CH2Cl2 are summarized in the
Experimental section. Both the monocorrole 1 [24] and
biscorroles 2–4 have a split Soret band centered at 400–
405 and 427–430 nm along with a broad Q-band at 586–
645 nm. Those spectral features in CH2Cl2 are all similar
to those of d-type hyperporphyrins [16, 24].
In MALDI/TOF MS, the main ionic pattern corres-
ponded to the molecular ion and this data agrees well
Fig. 1. Cyclic voltammograms of monomanganese corrole 1 and bismanganese biscorroles 2–4 in (a) PhCN and (b) pyridine
containing 0.1 M TBAP at a scan rate of 0.1 V/s. Some small reduction peaks marked by asterisks is due to trace impurities or
side reactions
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Mn(III) to Mn(II), the first process occurring at E1/2
=
gives what has been earlier assigned as a Mn(III) cor-
role π-anion radical in the case of the monomacrocycle
[24, 27]. A slightly different current-voltage curve is seen
for the biscorrole 4, which has the most flexible “Ox”
spacer. The cyclic voltammogram for this dyad in pyri-
dine resembles in part that of the dyads 2 and 3 and in
part that of the monocorrole 1 in PhCN, which also has a
reduction at E1/2 = -1.64 V.
-1.36 and the second at E1/2 = -1.64 V. Almost the same
behavior is seen for the biscorroles 2–4 as illustrated in
Fig. 1a, the only major difference between cyclic voltam-
mograms of the monocorrole and the dyads being the
relative intensities of the individual oxidation or reduc-
tion peak currents for the related metal-centered oxida-
tion or reduction processes in this solvent.
As indicated in Fig. 1, the first oxidation of dyads
in PhCN is split into two processes, the first ranging in
potential from E1/2 = 0.07 (compound 4) to 0.12 V (com-
pound 3) and the second from E1/2 = 0.40 (compound 3)
to 0.45V (compound 4). These two sets of electrode reac-
tions were assigned in the case of 1 to two different forms
of axially ligated Mn(IV) under the given solution condi-
tions, [(Cor)MnIV(PhCN)]+ in one case and (Cor)MnIVX
in the other, where X was an unknown anion, probably
ClO4-, from the supporting electrolyte [24].
We have previously shown that a single pyridine axial
ligand strongly coordinates to the Mn(III) center of the
neutral monomeric corrole in pyridine, 0.1 M TBAP [24]
and the same seems to occur for compounds 2 and 3,
each of which exhibits reversible one-electron reductions
at E1/2 = -1.47 to -1.49 V in this solvent. The compounds
1–4 also show reversible one-electron oxidations at
E1/2 = 0.42 to 0.48 V in pyridine and, in case of the dyads
2–4 there is an additional re-oxidation on the return scan
at Ep = 0.09 to 0.14 V (see Fig. 1b).
Two MnIV/MnIII re-reduction peaks are also observed
for dyads 2–4 in pyridine (Fig. 1b) and these are here
assigned to electrode reactions involving the reduction
of [(Cor)MnIV(py)]+ and [(Cor)MnIV(py)2]+ which were
characterized by thin-layer spectroelectrochemistry as
described in the discussion below. Although the cavity of
dyads 2–4 is probably not large enough for two pyridine
molecules to both easily fit inside, the overall oxidation
and re-reduction sequence of steps for 2–4 (at least for
one metallomacrocycle of the dyads) is then proposed to
occur in pyridine as shown in Equations 1a and 1b for
oxidation and Equation 1c for re-reduction.
(Cor)MnIII (py)  [(Cor)MnIV(py)]+ + e-
E1/2 = 0.46 to 0.48 V (1a)
[(Cor)MnIV(py)]+ + py  [(Cor)MnIV(py)2]+
(1b)
[(Cor)MnIV(py)2]+ + e  [(Cor)MnIII(py)] + py
Ep = 0.09 to 0.14 V
(1c)
An example of the two step UV-visible changes which
occur during oxidation of the dyad 4 and monocorrole
1 in pyridine is shown in Fig. 2 while similar spectral
changes involving a two step process are illustrated in
The oxidation of compounds 1–3 in pyridine gives the
Mn(IV) corrole at E1/2 = 0.42 to 0.47 V while reduction
of the same three compounds at E1/2 = -1.46 to -1.49 V
Fig. 2. UV-visible spectral changes of (a) 4 and (b) 1 during the oxidation processes in pyridine, 0.1 M TBAP
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P. ChEn et al.
Fig. 3. UV-visible spectral changes of 2 and 3 during the oxidation processes in pyridine, 0.1 M TBAP
Fig. 3 for 2 and 3. In each case, the spectral changes with
time involve a two-step process during the first oxidation
which is assigned to the electrochemical-chemical (EC)
mechanism given in Equations 1a and 1b.
Although the mono and bis-pyridine adducts of 1–4
are spectrally observed as products of the electrooxida-
tion in pyridine, a peak for oxidation or re-reduction
of the bis-pyridine adduct is not detected in the cyclic
voltammogram of the monocorrole 1, suggesting conver-
sion of [(Cor)MnIV(py)2]+ (E1/2 = 0.12 V) to the more eas-
ily reducible [(Cor)MnIV(py)]+ (E1/2 = 0.45 V) under the
application of a positive potential.
A further ring-centered oxidation of the biscorroles 2–4
is located at E1/2 = 1.07 to 1.10 V in PhCN (see Fig. 1) and
this potential may be compared to an E1/2 = 1.10 V for the
oxidation of 1 under the same solution conditions. The
UV-visible spectral changes during this electrooxidation
are consistent with the abstraction of one electron from the
conjugated π-ring system of the macrocycle to give a MnIV
corrole π cation radical which exhibits a broad band at 550–
750 nm as shown in Fig. 4 for the case of compound 4.
The spectral changes obtained during controlled poten-
tial reduction of 2–4 in a thin-layer cell was also paral-
lel to what was described earlier in the literature for the
monocorrole 1. The prevailing electron transfer mecha-
nism of the dyads also parallels what has been reported in
the literature for the monocorrole 1 and depends mainly
on the solvent (py or PhCN) and only to a small extent on
the structure of the investigated compound and the bridge
linking the two metallomacrocycles.
Fig. 4. UV-visible spectral changes of (BMes2COx)Mn2
4 during the first and second oxidations in PhCN, 0.1 M TBAP
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Fig. 5. UV-visible spectral changes of 2 and 1 during the reduction processes in pyridine, 0.1 M TBAP
The one-electron reduction of 1–3 in pyridine at
E1/2 = -1.46 to -1.49 V generates in each case an almost
identical UV-visible spectrum which is assigned as a
Mn(III) π-anion radical (see examples of spectra in Fig.
5). The two reductions of the biscorroles 2–4 in PhCN
at ~-1.36 and ~ -1.65 V are each assigned as a Mn(III)/
Mn(II) process, the first of which is followed by a fast
chemical reaction (an EC mechanism). The initial reduc-
tion gives the bis-manganese(II) corrole which reacts with
trace water in PhCN to regenerate a bis-manganese(III)
corrole having two axially coordinated hydroxide ligands
(as determined in the case of the monocorrole by spec-
troscopic titrations of the monomer with TBAOH) [24].
The homogeneously generated bis-Mn(III) corrole dyad
is then reduced to a bis-Mn(II) dyad at a more negative
potential of -1.65 V. These reactions are given in Equa-
tions 2–4 and an example of the two-step spectral changes
is shown in Fig. 6a where the two reductions occur
Fig. 6. UV-visible spectral changes of (a) 4 upon controlled potential reduction at -1.90 V and 1 during a stepwise reduction at
applied potentials of (b) -1.50 V and (c) -1.80 V in PhCN, 0.1 M TBAP
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P. ChEn et al.
sequentially when the applied potential in the thin-layer
cell is set at -1.90 V.
of the dyad form bis-acetate adducts upon the first oxi-
dation, the exact stoichiometry depending on the cavity
space inside of the dyad.
bis-(Cor)MnIII + 2e  [bis-(Cor)MnII]2-
Finally, it should be noticed that different oxidation
behavior is seen for the dyads 2 and 4 when CH2Cl2 is
used as a solvent in place of PhCN or pyridine. As shown
in Fig. 8, the cyclic voltammograms of 1 and 3 are simi-
lar to each other in shape and the first two oxidations are
due to different coordination of Mn(IV) as described in
the text. This contrasts with the first two oxidations of 2
and 4 where there is a “splitting” of the first or first and
second oxidation processes as is often observed for the
case of equivalent interacting redox centers [15, 21, 28].
As seen in the figure, the first of the two Mn(III)/Mn(IV)
processes of the monomer 1 which occurs at E1/2 = 0.03 V
is split into peaks at E1/2 = -0.13 and 0.01 V for the dyad
4 or E1/2 = -0.12 and 0.01 V for the dyad 2. The second
Mn(III)/Mn(IV) process located at E1/2 = 0.32 V for the
monomer 1 is also split into two processes at E1/2 = 0.20
E1/2 = ~ -1.36 V
(2)
bis-(Cor)MnII]2- + 4H2O  [bis-(Cor)MnIII(OH)2]4-
+ 2H+ + H2
(3)
[bis-(Cor)MnIII(OH)2]2- + 2e  [bis-(Cor)MnII(OH)4]6-
E1/2 = ~ -1.65 V
(4)
The first set of spectral changes during controlled
potential reduction occurs from 0 to 80 s and generates
a species with intense Soret and visible bands at 483 nm
and 658 nm, respectively. The second set of spectral
changes, from 81 to 574 s, gives a spectrum with a
Soret band at 483 nm and a more intense visible band at
672 nm. Almost identical spectral changes are seen dur-
ing controlled potential reduction of 1 (Figs 6b and 6c
when the applied potential is first set at -1.50 V and then
switched to -1.80 V). It can therefore be concluded that
the biscorroles 2–4 and monocorrole 1 undergo similar
electroreduction mechanisms.
The effect of adding acetate ion to solutions of the
dyad 2–4 in PhCN is similar to what was reported for
1 under the same experimental conditions [24]. A com-
parison of cyclic voltammograms for 1 and 3 is shown
in Fig. 7. The quite similar electrooxidation behavior for
1 and 3 suggests that oxidizing one [(Cor)MnIII(OAc)]-
macrocycle of the dyad 3 generates (Cor)MnIV(OAc)
and this is followed by addition of a second axial ligand
to the Mn(IV) metal center to give [(Cor)MnIV(OAc)2]-.
The relevant electron transfer mechanism is shown in the
right hand side of Scheme 1 where the listed potentials
of the MnIII/MnIV process are given for 3 and listed as
E1/2 = 0.23 for the oxidation and Epc = -0.20 V for the
re-reduction. As described earlier for the case of pyridine
binding to the oxidized dyads, one or both corrole parts
Fig. 7. Cyclic voltammograms of monomanganese corrole
1 and bismanganese biscorroles 3 in PhCN containing 0.1 M
TBAOAc at a scan rate of 0.1 V/s
Fig. 8. Cyclic voltammograms of monomanganese corrole 1
and bismanganese biscorroles 2–4 in CH2Cl2 containing 0.1 M
TBAP at a scan rate of 0.1 V/s
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Table 1. Half-wave and peak potentials (V vs. SCE) of mono-manganese and bis-manganese complexes in different solvents
containing 0.1 M TBAP. The major reactions of the dyads are marked by the red box
Solvent
PhCN
Compound
#
Oxidation
(Cor)MnIII/MnIV
Reduction
Cor ring
(Cor) MnIII/MnII
(Mes2PhCor)Mna
(BMes2CX)Mn2
(BMes2CA)Mn2
(BMes2COx)Mn2
1
2
3
4
1.07
1.07
1.08
1.10
0.45
0.44
0.40
0.45
0.12
0.10
0.12
0.07
-1.36
-1.44b
-1.36b
-1.36
-1.64
-1.67
-1.65
-1.65
pyridine
CH2Cl2
(Mes2PhCor)Mna
(BMes2CX)Mn2
(BMes2CA)Mn2
(BMes2COx)Mn2
1
2
3
4
0.42
0.46
0.47
0.48
-1.46
-1.49
-1.47
-1.50
0.09 Epc
0.13Epc
0.14Epc
-1.64
(Mes2PhCor)Mn
(BMes2CX)Mn2
(BMes2CA)Mn2
(BMes2COx)Mn2
1
2
3
4
1.00
0.32
0.33, 0.20
0.29
0.03
-1.45b,c
not observedc
not observedc
-1.50b,c
1.11b, 0.99
1.17b, 0.99
1.15b, 1.02
0.01, -0.12
0.08
0.25
0.01, -0.13
a Data taken from Reference 24. b Peak potential at a scan rate of 0.1 V/s. c Some small reduction peaks due to trace impurities or
side reactions were observed at Ep = -0.49 to -1.10 V at a scan rate of 0.1 V/s.
Scheme 1. Redox reactions of monocorrole 1 or one of the two corroles in the dyad 2–4 under different solution conditions (listed
potentials are for compound 3 at scan rate of 0.1 V/s)
and 0.33 V in the case of 2. Surprisingly, no splitting is
seen for the dyad 3 containing the A bridge where the
first two oxidations are located at similar E1/2 values as for
the monocorrole 1 (see top of Fig. 8). The global second
one-electron oxidation of the three dyads occurs at the
E1/2 = 0.99 to 1.02 V for compounds 2, 3 and 4 and these
potentials are similar to the E1/2 = 1.00 V measured for
oxidation of the monocorrole 1.
A summary of half wave and peak potentials in PhCN,
pyridine and CH2Cl2 is given in Table 1. Electrochemical
properties of the monocorrole 1 and each metallomacro-
cycle of the dyad 2–4 are summarized in Scheme 1 which
includes results from the earlier report [24] combined
with data from additional experiments described in the
present study.
CONCLUSION
We have reported electrochemical and spectroelec-
trochemical properties of three newly synthesized man-
ganese biscorrole dyads in PhCN, pyridine and CH2Cl2.
Their electron transfer properties in PhCN and pyridine
and the electron transfer site was evaluated as a function
of the specific reaction conditions.An interaction between
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P. ChEn et al.
two macrocycles of some investigated biscorrole dyads is
observed during their electrooxidation in the non-binding
solvent CH2Cl2. It is anticipated that results obtained for
the currently examined compounds might provide a basis
for applications involving the need to encapsulate guest
molecules inside the bismacrocycle pocket.
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Acknowledgements
The support of the Robert A. Welch Foundation
(K.M.K., Grant E-680) and the French Ministry of Research
(MENRT), CNRS (UMR 5260) and Burgundy Region
are gratefully acknowledged. Maya El Ojaimi thanks the
French Ministry of Research for a three year PhD grant.
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