Synthetic, structural, and photophysical exploration of meso-pyrimidinylsubstituted AB2-corroles

Article abstract of DOI:10.1002/chem.201000008

meso-Pyrimidinyl-substituted AB₂-corroles were efficiently synthesized starting from 5-mesityldipyrromethane and various 2-substituted 4,6-dichloropyrimidine-5-carbaldehydes. The corroie yield was significantly enhanced by optimization of the amount of Lewis acid catalyst (BF3-OEt2). The main advantage of pyrimidinylcorroles over other meso-triarylcorroles is their wide range of functionalization possibilities, which has been explored by nucleophilic and electrophilic aromatic substitution, and Pd-catalyzed crosscoupling reactions. Stepwise substitution of the chlorine functions afforded asymmetrically substituted pyrimidinylcorroles. Due to the lability of the freebase corroie macrocycles, functionaliza tion of the corroie periphery was preferentially performed on the Cu-metalated counterparts. Functionalized freebase AB₂-pyrimidinylcorroles were, however, readily accessible by the reversible sequence Cu insertion and subsequent reductive demetalation. AB₂-pyrimidinylcorroles can hence be regarded as highly versatile platforms towards more sophisticated corrole systems. X-ray analysis of a bis(4-tert-butylphenoxy)-substituted Cu-pyrimidinylcorrole showed the typical features of a Cu-corrole: short N-Cu distances and a saddled corroie plane. The absorption spectra and photophysical properties of some representative freebase AB₂-pyrimidinylcorroles were examined in depth. The absorption spectra displayed typical corroie features: intense spin-allowed π-π* bands, which can be classified as Soret- and Q-type bands. The photophysical properties, investigated both in fluid solution at room temperature and in rigid matrix at 77 K, were governed by the lowestlying π-π* singlet state; however, in most cases, a state with partial chargetransfer character (from the corroie ring to the pyrimidinyl group) was proposed to contribute to the dynamic properties of the emissive level.

Full text of DOI:10.1002/chem.201000008

FULL PAPER
DOI: 10.1002/chem.201000008
Synthetic, Structural, and Photophysical Exploration of meso-Pyrimidinyl-
Substituted AB2-Corroles
Thien H. Ngo,[a] Fausto Puntoriero,*[b] Francesco Nastasi,[b] Koen Robeyns,[c]
Luc Van Meervelt,[c] Sebastiano Campagna,[b] Wim Dehaen,*[a] and Wouter Maes*[a, d]
Abstract: meso-Pyrimidinyl-substituted
AB2-corroles were efficiently synthe-
sized starting from 5-mesityldipyrrome-
thane and various 2-substituted 4,6-di-
chloropyrimidine-5-carbaldehydes. The
corrole yield was significantly en-
hanced by optimization of the amount
of Lewis acid catalyst (BF3·OEt2). The
main advantage of pyrimidinylcorroles
over other meso-triarylcorroles is their
wide range of functionalization possi-
bilities, which has been explored by nu-
cleophilic and electrophilic aromatic
substitution, and Pd-catalyzed cross-
coupling reactions. Stepwise substitu-
tion of the chlorine functions afforded
asymmetrically substituted pyrimidinyl-
corroles. Due to the lability of the free-
base corrole macrocycles, functionaliza-
tion of the corrole periphery was pref-
erentially performed on the Cu-meta-
lated counterparts. Functionalized free-
base AB2-pyrimidinylcorroles were,
however, readily accessible by the re-
versible sequence Cu insertion and
subsequent reductive demetalation.
AB2-pyrimidinylcorroles can hence be
regarded as highly versatile platforms
towards more sophisticated corrole sys-
tems. X-ray analysis of a bis(4-tert-bu-
tylphenoxy)-substituted Cu–pyrimidi-
nylcorrole showed the typical features
and a saddled corrole plane. The ab-
sorption spectra and photophysical
properties of some representative free-
base AB2-pyrimidinylcorroles were ex-
amined in depth. The absorption spec-
tra displayed typical corrole features:
intense spin-allowed p–p* bands, which
can be classified as Soret- and Q-type
bands. The photophysical properties,
investigated both in fluid solution at
room temperature and in rigid matrix
at 77 K, were governed by the lowest-
lying p–p* singlet state; however, in
most cases, a state with partial charge-
transfer character (from the corrole
ring to the pyrimidinyl group) was pro-
posed to contribute to the dynamic
properties of the emissive level.
ꢀ
of a Cu–corrole: short N Cu distances
Keywords: charge transfer
· cor-
roles · luminescence · pyrimidines ·
UV/Vis spectroscopy
[a] T. H. Ngo, Prof. Dr. W. Dehaen, Prof. Dr. W. Maes
[d] Prof. Dr. W. Maes
Molecular Design and Synthesis, Department of Chemistry
Katholieke Universiteit Leuven, Celestijnenlaan 200F
3001 Leuven (Belgium)
Institute for Materials Research (IMO)
Research Group Organic and (Bio)Polymer Chemistry
Hasselt University
Fax : (+32)16-327990
E-mail: wim.dehaen@chem.kuleuven.be
Universitaire Campus, Agoralaan Building D
3590 Diepenbeek (Belgium)
Fax : (+32)11-268399
E-mail: wouter.maes@uhasselt.be
[b] Prof. Dr. F. Puntoriero, Dr. F. Nastasi, Prof. Dr. S. Campagna
Dipartimento di Chimica Inorganica
Chimica Analitica e Chimica Fisica, Universitꢀ di Messina
Centro Interuniversitario per la Conversione Chimica
dellꢁEnergia Solare
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201000008. It includes additional
experimental and characterization data, H and 13C NMR spectra for
1
98166 Vill. S. Agata, Messina (Italy)
Fax : (+39)90259456
E-mail: fpuntoriero@unime.it
all novel (pyrimidinyl)corroles, luminescence spectra of 4a,b in MeCN
and CH2Cl2 at RT, and extra details and figures for the X-ray crystal-
lographic structure of 7c.
[c] Dr. K. Robeyns, Prof. Dr. L. Van Meervelt
Biomolecular Architecture, Department of Chemistry
Katholieke Universiteit Leuven, Celestijnenlaan 200F
3001 Leuven (Belgium)
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Introduction
substituted porphyrins,[10] heteracalix[m]arene[m]pyrimi-
dines,[11] and pyrimidine-based (porphyrin) dendrimers.[12,13]
During the course of our studies on pyrimidinylporphyrins,
it was discovered that a slight modification of the reaction
conditions, as optimized for porphyrins, results in the forma-
tion of either expanded (penta- and hexaphyrins)[14] or con-
tracted[15] porphyrin analogues. The major advantage con-
cerning the introduction of dichloropyrimidinyl moieties on
the meso positions of a porphyrinoid macrocycle is the wide
scope of functionalization reactions that can be performed
on the dichloropyrimidine units. “Double-picket-fence”-
functionalized porphyrins and hexaphyrins have been ob-
tained by efficient and operationally simple nucleophilic ar-
omatic substitution (SNAr) and Suzuki cross-coupling reac-
tions.[10,14] In previous communications, specific synthetic as-
pects of pyrimidinylcorroles have been described.[9,15–17] In
this paper, we report a detailed multidisciplinary study on
the synthesis and functionalization, structural elucidation
and photophysical properties of meso-pyrimidinyl-substitut-
ed AB2-corroles (A=4,6-dichloropyrimidin-5-yl).[18]
Since the first efficient one-pot syntheses of meso-triarylcor-
roles by Gross and Paolesse in 1999,[1] corrole chemistry has
grown almost exponentially, thus enabling its evolution over
the past ten years from a narrow, mainly synthetically ori-
ented research topic to a mature and flourishing interdisci-
plinary field. Driven by related studies on their well-known
porphyrin congeners, corroles have recently been applied in
various domains (e.g., catalysis, sensor design, molecular
electronics, and medical imaging and therapy), in which cor-
roles regularly display superiority compared to related oligo-
pyrrolic macrocycles.[2] In spite of the tremendous synthetic
progress that has been made in the corrole field over the
last decade,[3,4] some synthetic challenges remain and further
efforts are certainly still required to elucidate and exploit
the full potential and promises that corroles hold for up-to-
date applications.
Among the strategies that can be used to obtain more so-
phisticated corrole structures, corrole functionalization has
mostly been achieved by insertion of the required functional
moieties on the corrole precursors (aromatic aldehydes and
derived dipyrromethanes).[3] However, not all aldehyde
building blocks afford corroles in equally good yields and
precious starting material may hence be lost. Furthermore,
depending on the precursors, optimization of the macrocyc-
lization conditions may be required. Alternatively, post-mac-
rocyclization functionalization of the corrole perimeter is
often achieved by the introduction of functional groups on
the b-pyrrolic positions (e.g., by bromination, nitration,
chlorosulfonation, or hydroformylation).[3] A particular type
of corrole modification through the pyrrolic units involves
cycloaddition reactions.[5] Only a few groups have reported
post-macrocyclization elaborations by means of the meso
positions of the contracted porphyrin framework.[6] Ad-
vanced corrole research would certainly benefit from a gen-
eral triarylcorrole scaffold that can be prepared in a high
yield and on a large scale, is stable enough for further ma-
nipulations, and enables smooth access to a wide variety of
functionalized corroles specifically designed for modern ap-
plications.
Results and Discussion
Synthesis of the AB2-pyrimidinylcorrole scaffold: In 2001,
one of our groups contributed to the early stages of synthet-
ic corrole chemistry by exploring the synthesis of sterically
encumbered triarylcorroles starting from aromatic aldehydes
and 5-aryldipyrromethanes.[16] Upon condensation of 4,6-di-
chloropyrimidine-5-carbaldehyde (1a) and 5-(2,6-dichloro-
phenyl)dipyrromethane (2a) in dichloromethane at room
temperature (RT), catalyzed by borontrifluoride dietherate
(BF3·OEt2), and subsequent oxidative cyclization with p-
chloranil, the first AB2-pyrimidinylcorrole 3 was obtained in
20% yield (Scheme 1).
At that time, no corrole material could be isolated start-
ing from 1a and 5-mesityldipyrromethane (2b). The A2B2-
porphyrin analogue was solely obtained in a remarkably
high yield (53%). Later on, in a detailed study towards a
more general procedure for AB2-pyrimidinylcorroles, it was
observed that the desired pyrimidinylcorrole 4a could be
A noteworthy complication of performing functionaliza-
tion reactions on free-base (Fb) corroles is the lability that
is often observed for these metal-free derivatives under the
combined influence of light and O2, thereby resulting in
lower yields and troublesome purifications. This bottleneck
could be solved by conversion to a more stable metallocor-
role derivative if efficient demetalation protocols were to be
available (as known for metalloporphyrins). Until recently,
studies on corrole demetalation procedures were scarce.[7]
However, recent breakthroughs on the (reductive) demeta-
lation of Cu– and Mn–corroles allow the use of a metala-
tion/demetalation sequence as a protection/deprotection
strategy towards elaborated Fb–corroles.[8,9]
Within one of our research groups, we have been studying
the synthesis and reactivity of 4,6-dichloropyrimidines as
versatile structural building blocks for meso-pyrimidinyl-
Scheme 1. Synthesis of AB2-pyrimidinylcorrole 3.
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synthesized in 18% yield upon using a tenfold decreased
concentration of Lewis acid catalyst (0.085 equiv BF3·OEt2),
simultaneously affording 25% of the A2B2-porphyrin coun-
terpart (Scheme 2).[15]
matographic purification of the corrole. It was observed that
the A2B2-porphyrin content gradually decreased when less
BF3·OEt2 was used. The maximum corrole yield was ob-
tained upon adding 0.043 equiv of Lewis acid. Under these
conditions, corrole 4a was isolated in as much as 35% yield,
an appreciable increase and a nice result compared to gener-
ally observed yields in corrole synthesis.[3,4] By simple varia-
tion of the amount of BF3·OEt2, the reaction outcome could
be varied from 50% A2B2-porphyrin and no AB2-corrole to
35% corrole and 6% porphyrin. On applying the optimized
protocol to the synthesis of corroles 4b and 4c, the yield for
4c was increased to 22%, whereas the yield for 4b dropped
to 14%. The highest yield (27%) for thiomethyl-substituted
AB2-corrole 4b was obtained on using 0.068 equiv of cata-
lyst. The optimum catalyst concentration hence seems to be
dependent on the substituent on the pyrimidinecarbalde-
hyde precursor.[21]
It is worth mentioning that the same conditions, as opti-
mized for condensation of mesityldipyrromethane (2b) and
pyrimidinecarbaldehydes 1a–d, could also be applied for the
preparation of analogous AB2-corroles 6a–d, derived from
2b and other aromatic aldehydes (Scheme 3).[22]
Scheme 2. Synthesis of AB2-pyrimidinylcorroles 4a–d and the corre-
sponding Cu analogues 5a–d.
As a first step towards variation of the pyrimidinylcorrole
periphery, the possibility to synthesize AB2-corroles starting
from 2b and various 2-substituted 4,6-dichloropyrimidine-5-
carbaldehydes 1b–d was explored. Mesityldipyrromethane
was chosen for reasons of availability and solubility of the
final corrole, and it can easily be prepared through a recent-
ly optimized procedure that allows one to obtain aryldipyr-
romethanes in high yields by simple precipitation from an
acidic aqueous solution.[19] An additional advantage of this
method is the small excess of pyrrole (3 equiv) that is re-
quired. Pyrimidinecarbaldehyde building blocks 1a–d can
readily be synthesized by chloroformylation of the 4,6-dihy-
droxypyrimidine precursors, in turn usually accessible start-
ing from the respective amidines.[20a–c] 4,6-Dichloro-2-meth-
ylsulfanylpyrimidine-5-carbaldehyde (1b) was obtained
through methylation and subsequent chloroformylation of
thiobarbituric acid.[20d] Flash chromatographic purification of
the pyrimidinecarbaldehydes is crucial to obtain satisfactory
yields for the tetrapyrrolic chromophores. Pyrimidinylcor-
roles 4b–d were synthesized in a straightforward way in fair-
to-good yields (20% for 4b, 13% for 4c and 4d) from the
substituted precursors upon condensation with mesityldipyr-
romethane catalyzed by 0.085 equiv BF3·OEt2 (Scheme 2).
The AB2-corroles had to be chromatographically separated
from the concurrently formed A2B2-porphyrins.[15]
Scheme 3. (Nonpyrimidinyl) AB2-corroles 6a–d synthesized by means of
the optimized procedure.
Functionalization scope: Variation of the AB2-pyrimidinyl-
corrole framework can be achieved through substitution of
the chlorine functions on the electron-deficient meso-pyrimi-
dinyl unit. A unique feature of meso-pyrimidinylcorroles is
the fact that the substituents are introduced at the ortho,or-
tho’-positions, and hence are located above and below the
corrole plane. Such double-picket-fence corroles[6] can have
additional advantages for peculiar applications (e.g., energy-
transfer relays or regio- and stereoselective corrole-based
catalysis).
The amount of Lewis acid catalyst appeared to be a cru-
cial parameter to obtain either the meso-pyrimidinyl-substi-
tuted AB2-corrole or the A2B2-porphyrin as the major prod-
uct. Hence, an optimization study of the BF3·OEt2 content
was performed to maximize the corrole yield. The optimiza-
tion was done for corrole 4a and a 1:1 ratio of mesityldipyr-
romethane and pyrimidinecarbaldehyde 1a was used, rather
than the stoichiometric 2:1 ratio. The excess of pyrimidine-
carbaldehyde could, however, easily be recovered on chro-
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F. Puntoriero, W. Dehaen, W. Maes et al.
For further post-macrocyclization modifications of the
corrole periphery, AB2-corroles 4a and 4b were chosen as
substrates of preference (highest optimized yield and addi-
tional synthetic versatility of 4b, vide infra). Functionaliza-
tion was initially performed starting from the Fb derivatives.
It was, however, quickly observed that the target substituted
Fb–corroles were generally obtained in rather low yields,
which can probably be ascribed to the inherent (oxidative)
lability of the Fb AB2-pyrimidinylcorroles. This oxidative
degradation is also evident from the olive-green band that
precedes the pyrimidinylcorrole on chromatographic purifi-
cation (silica), earlier identified as a corrole oxidation prod-
uct.[4] Compared to the currently most widely studied and
used relatively stable Fb 5,10,15-tris(pentafluorophenyl)cor-
role (tpfc),[1a,b] only one stabilizing electron-withdrawing
meso-group is available. Hence, it was decided to perform
the functionalization studies on the Cu–pyrimidinylcorrole
analogues 5a,b. Among the wide range of presently de-
scribed metallocorroles, Cu–corroles occupy a special place.
Cu–corroles are readily accessible, do not require additional
ligands to complete their coordination sphere, and have a
diamagnetic ground state, which has originally been over-
simplified to a CuIII state.[23] More recent studies provide
new insights on the electronic structure of Cu–corroles.[24]
Cu–corroles 5a–d were easily synthesized from AB2-pyrimi-
dinylcorroles 4a–d by employing copper(II) acetate in pyri-
dine at RT (78–95% yield; Scheme 2).[15] Cu insertion can
also smoothly be achieved in THF.[9]
Scheme 4. Functionalization of Cu–AB2-pyrimidinylcorroles 5a,b by
SNAr.
Inspired by the success of similar modifications on pyrimi-
dinylporphyrins, peripheral substitution of the pyrimidinyl-
corrole skeleton was first pursued by means of SNAr reac-
tions. Cu-metalated AB2-pyrimidinylcorroles 5a,b were no-
ticeably less reactive towards substitution than the analo-
gous Fb A2B2-porphyrins. Under SNAr conditions that
enable smooth substitution on a pyrimidinylporphyrin scaf-
fold (excess 4-tert-butylphenol, DMF, 908C, K2CO3 base,
[18]crown-6, 48 h),[10a,12d] Cu–corrole 5a was converted into
monosubstituted AB2-corrole 7a in 87% yield, without sig-
nificant disubstitution (Scheme 4). Under similar conditions,
thiomethyl-substituted Cu–corrole 5b afforded 71% of
monofunctionalized AB2-corrole 7b, whereas 9% of starting
compound 5b could be recovered (Scheme 4). Selective
monosubstitution by SNAr is hence feasible on a pyrimidi-
nylcorrole scaffold. On the other hand, twofold substitution
could be achieved using rather harsh conditions (DMSO,
1758C by microwave irradiation, K2CO3, 1 h) to afford di-
Scheme 5. Functionalization of Cu–AB2-pyrimidinylcorrole 5a by SEAr
(chlorination) and subsequent demetalation.
In 2003, we explored the functionalization of A2B2-pyrimi-
dinylporphyrins by Suzuki cross-coupling reactions to obtain
sterically encumbered porphyrins with potential in regiose-
lective catalysis.[10b] Application of the same reaction condi-
tions to Cu–pyrimidinylcorrole 5a furnished AB2-corrole 9
with a sterically shielded metal center in a satisfactory 75%
yield (Scheme 6). In like fashion, Cu–corrole 5a was also
subjected to a Stille cross-coupling reaction with 2-(tributyl-
stannyl)thiophene to afford dithienyl-substituted Cu–corrole
10 in 73% yield (Scheme 6).[15]
ACHTUNGTRENNUNG
The corrole substitution pattern could additionally be al-
tered by Liebeskind–Srogl cross-coupling reactions. The 2-
thiomethyl moiety of Cu–corrole 5b can be exchanged for
other groups by Liebeskind–Srogl reactions, thus providing
an alternative for the earlier described protocol in which the
introduction of different groups at this site was established
using specific pyrimidinecarbaldehyde precursors. This is
particularly useful if the requisite 4,6-dichloropyrimidine-5-
carbaldehyde building block cannot trivially be obtained.
Cu–corrole 11 was synthesized in 61% yield through substi-
positions of the corrole framework through electrophilic ar-
omatic substitution (SEAr) procedures is a generally applied
strategy towards more elaborate corrole macrocycles.[3]
Chlorination of corroles has, however, not been reported
yet, at least not for aromatic corroles.[25] Treatment of Cu–
corrole 5a with N-chlorosuccinimide (NCS) in o-dichloro-
benzene at high temperature (140/908C) resulted in the for-
mation of octachlorinated Cu–pyrimidinylcorrole 8, which
could be isolated in 46% yield (Scheme 5).[9]
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AB2-Corroles
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yield). Disubstituted AB2-corroles 14 and 15 were both ob-
tained in the same yield (81%) upon employing Cs2CO3
base at 1208C in DMF. p-Dodecylphenoxy-substituted cor-
role 14 was designed as an active electrode material for
supramolecular sensor applications.[26] The possibility to in-
troduce two phenol nucleophiles in a stepwise manner was
examined starting from monosubstituted Cu–corrole 12a.
Upon treatment of this pyrimidinylcorrole with 4-bromo-
phenol (ꢁ4 equiv, DMF, K2CO3, 90/1208C, 28 +20 h), ex-
tensive scrambling was observed. Not only the desired asym-
metrically substituted corrole 16a was obtained (28%), but
also mono- and bis(4-bromophenoxy)-substituted corroles
16c (20%) and 16b (21%), indicative of the dynamic (re-
versible) character of the SNAr reaction. A proper choice
and order of substituting nucleophiles is required if one
wants to enhance the efficiency of this strategy towards
asymmetrically disubstituted derivatives. This complication
can of course be avoided by performing Pd-catalyzed cross-
coupling reactions on the monosubstituted derivatives or
vice versa. AB2-pyrimidinylcorrole 17 was obtained by a
tandem Suzuki–SNAr reaction in a modest 34% yield. When
a similar protocol was applied to Cu–corrole 5b, selective
monosubstitution by Suzuki cross-coupling (phenylboronic
Scheme 6. Functionalization of Cu–AB2-pyrimidinylcorrole 5a by Pd-cat-
alyzed cross-coupling reactions (Suzuki/Stille).
tution of the methylsulfanyl moiety with 4-cyanophenylbor-
onic acid (Scheme 7).[15]
The rather selective access to monosubstituted Cu–corrole
7a by SNAr is attractive, since it enables stepwise introduc-
tion of different moieties by sequential substitution of both
acid, [PdACTHNGUTERN(NUG PPh3)4], toluene, aqueous Na2CO3) afforded pyri-
midinylcorrole 18a in 79% yield. Subsequent treatment
with an excess of 4-tert-butylphenol (4 equiv) yielded 76%
of the asymmetrical AB2-corrole 18b (DMF, K2CO3,
[18]crown-6, 1 h microwave at 1758C).
Both SNAr and Suzuki reactions were also successful on
Fb–corroles, but the obtained yields were significantly
lower. Bis(4-tert-butylphenoxy)-substituted Fb–corrole 19
was, for instance, isolated in 29% yield (6 equiv 4-tert-butyl-
phenol, 1208C, DMF, Cs2CO3, 14 h), compared with 81%
for the analogous Cu–corrole 15.[9] A Suzuki cross-coupling
reaction with phenylboronic acid starting from Fb–AB2-cor-
role 3 afforded less than 40% of the (impure) disubstituted
derivative, whereas a mixture of (almost pure) mono- and
disubstituted AB2-pyrimidinylcorroles 20a (62%) and 20b
(29%) was obtained by means of a similar procedure start-
ing from 4a (toluene, [PdACHTNUGTRNEUG(N PPh3)4], 3 equiv phenylboronic
Scheme 7. Variation of the 2-pyrimidinyl position by Liebeskind–Srogl
cross-coupling on thiomethyl-substituted Cu–corrole 5b.
acid, aqueous Na2CO3, 24 h). The functionalized Fb–corroles
were often not completely pure upon the first chromato-
graphic purification (silica) and significant decomposition
occurred upon repeating this procedure, thus reflecting the
modest (oxidative) stability of these macrocycles.
chlorine groups, which could give access to even more so-
phisticated asymmetrically substituted meso-pyrimidinylcor-
roles. It also provides a useful entry towards inherently
chiral corrole macrocycles. For this purpose, additional SNAr
reactions were examined. Substitution on Cu–AB2-corrole
5a with m-cyanophenol (1.7 equiv) in DMF at 708C
(K2CO3, [18]crown-6, 24 h) afforded majorly monosubstitut-
ed Cu–corrole 12a (79% yield). When the same procedure
was carried out at 908C (1.6 equiv m-cyanophenol), a mix-
ture of mono- and disubstituted Cu–corroles was obtained
(57% 12a, 45% 12b). The optimum temperature for mono-
and disubstitution seems to be nucleophile dependent.
Demetalation: For a number of corrole applications, it could
be desirable to take advantage of particular intrinsic Fb–cor-
role features (e.g., their luminescent properties). On the
other hand, functionalization of Fb–corroles is often trou-
bled by the modest stability of many metal-free derivatives,
which is considerably less of a problem for metallocorroles.
One of the obvious solutions to this dilemma would be to
apply a metalation/demetalation cycle as a protective strat-
egy, thereby enabling smooth corrole derivatization.
Mono
substitution with 4-chlorothiophenol was achieved at
Within one of our groups, a highly efficient, generally ap-
plicable, reductive demetalation protocol for Cu–corroles
908C (13: 3.4 equiv thiophenol, DMF, K2CO3, 20 h, 81%
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F. Puntoriero, W. Dehaen, W. Maes et al.
has been established.[9] In the presence of tin(II) chloride,
Cu–corroles, which are nonemissive, are smoothly converted
to their fluorescent Fb analogues in acidic medium at RT.
The demetalation procedure is also applicable to Cu–AB2-
pyrimidinylcorroles and, as an illustration of the potential of
the method, functionalized Fb–pyrimidinylcorroles 19, 22,
and 23 were prepared in high yields. Two specific cases
merit closer attention. Since the direct SNAr functionaliza-
tion of pyrimidinylcorrole 4b with 4-tert-butylphenol afford-
ed only 29% of the desired disubstituted AB2-corrole 19,
the three-step detour by means of Cu metalation (94%),
functionalization on the Cu–corrole stage (81%), and reduc-
tive demetalation (90%) was proven to be more efficient
(68% general yield).[9] Moreover, both the metalation and
demetalation procedures are operationally simple and pro-
ceed very fast. Another particular case is octachlorinated
Cu–corrole 8 (Scheme 5). When this corrole was subjected
to the demetalation conditions, partial dehalogenation was
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observed. To limit dechlorination, only one equivalent of
tin(II) chloride had to be used and 20% of the unique Fb–
corrole 21 was isolated, whereas 70% of unreacted starting
material could be recovered as well.[9]
electrospray mass spectrometry (ESIMS), and UV/Vis spec-
troscopy. The developing paramagnetism with increasing
temperature is clearly identifiable in the H NMR spectra of
the Cu–pyrimidinylcorroles, which show broadened signals
for the b-pyrrolic protons at RT (see the Supporting Infor-
mation).
In view of recent hypotheses on the true electronic nature
of Cu–corrole complexes and the related noninnocence of
the corrolato ligand,[24] additional structural elucidations of
novel Cu–corroles are of particular appeal. Diffraction-qual-
ity single crystals of Cu–corrole 7c were obtained by slow
evaporation from a CHCl3/hexane solution. Two crystallo-
graphically independent corrole entities, with similar struc-
tural features, are observed in the asymmetric unit
(Figure 1). The Cu atom resides in the center of the corrola-
1
Metallocorroles: Besides Cu–pyrimidinylcorroles, some
other metallocorrole derivatives were also prepared
(Scheme 8). Rather modest yields were obtained for these
Scheme 8. meso-Pyrimidinyl-substituted AB2-metallocorroles 25–27.
metal-insertion reactions under standard literature condi-
tions (not optimized for AB2-pyrimidinylcorroles). CoIII–pyr-
imidinylcorrole 25 was synthesized in 41% yield upon treat-
ment of Fb–corrole 4a with an excess of cobalt(II) acetyl-
ACHTUNGTRENNUNGacetonate (CH2Cl2/ethanol, 24 h) and subsequent addition of
triphenylphosphine.[27] AgIII insertion in AB2-corrole 4a was
achieved in 32% yield by means of reaction with silver(I)
acetate in pyridine (5 min at 808C),[7b] whereas GaIII–corrole
27 was obtained in 16% yield through addition of gallium-
ACHTUNGTRENNUNG(III) chloride to Fb precursor 4a in pyridine at reflux condi-
tions.[28] The low yield for the Ga–corrole might be due to
partial hydrolysis of the dichloropyrimidinyl moiety initiated
by (very hygroscopic) GaCl3.
A meso-pyrimidinylcorrole could also be prepared start-
ing from 5-(pentafluorophenyl)dipyrromethane.[19] Under
the conditions optimized for the combination of pyrimidine-
carbaldehyde 1a and mesityldipyrromethane (0.043 equiv
BF3·OEt2), AB2-corrole 24 was isolated in only 3% yield.
The macrocyclization reaction therefore needs to be opti-
mized for each dipyrromethane building block independent-
ly. Functionalization by SNAr on this corrole may be compli-
cated due to competitive fluorine substitution, especially in
view of the elevated temperature required for meso-chloro-
pyrimidinyl substitution, but smooth and selective Pd-cata-
lyzed cross-coupling reactions can be foreseen. Unfortunate-
ly, upon Cu metalation of 24, most of the corrole material
was lost. It seems that particular care has to be taken to
obtain the Cu derivatives of the most electron-deficient cor-
role macrocycles, as earlier observed for Cu–(tpfc).[9] Metal-
ation might, however, not be essential in this case due to the
higher stability of the electron-deficient Fb–corrole frame-
work.
Figure 1. ORTEP representation (with standard corrole numbering) of
Cu–AB2-pyrimidinylcorrole 7c, determined by X-ray crystallography
(top). Thermal ellipsoids are set at 50% probability. Only one out of two
crystallographically independent molecules is shown. Hydrogen atoms,
disorder, and incorporated solvent (CHCl3) have been omitted for clarity.
Selected bond lengths [ꢃ], angles [8], and torsion angles [8] (one entity):
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
Cu N1 1.873, Cu N2 1.899, Cu N3 1.888, Cu N4 1.884, C1 C19 1.421,
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
C4 C5 1.395, C5 C6 1.421, C9 C10 1.392, C10 C11 1.415, C14 C15
ꢀ
1.419, C15 C16 1.390; N1-Cu-N2 91.7, N1-Cu-N4 81.6, N2-Cu-N3 96.7,
N3-Cu-N4 91.8, N1-Cu-N3 166.9, N2-Cu-N4 167.8, C4-C5-C6 122.0, C9-
C10-C11 125.1, C14-C15-C16 122.5, N1-C1-C19-N4 11.6. Side view along
ꢀ
the C18 C12 axis (bottom): Hydrogen atoms and all atoms of the meso-
phenyl groups, except for the ipso-carbon atom of the pyrimidinyl
moiety, have been removed for clarity.
to N4 cavity with a distorted square-planar coordination.
ꢀ
The Cu Npyrrole bond lengths are not near-identical, as ob-
served for a few earlier obtained structures, and range from
1.880 to 1.892 ꢃ in one unit and 1.873 to 1.899 ꢃ in the
other entity.[23a,c,e,f,24] These relatively short distances have
been used to confirm the postulated low-spin CuIII center in
the past, but recent results have shown that the ground state
Structural characterization: All AB2-pyrimidinylcorroles
were fully characterized by NMR spectroscopy (1H and 13C),
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F. Puntoriero, W. Dehaen, W. Maes et al.
might be better described as an open-shell singlet CuII–cor-
C2ꢀ
rolato state.[23a,c,e,f,24] As previously observed for other Cu–
corroles, the corrole macrocycle shows a saddled conforma-
tion, that is, the pyrrole rings lie (1,3-)alternately above and
below the corrole plane. Ghosh and co-workers have recent-
ly reported that Cu–corroles are inherently saddled, even
without sterically hindered substituents that engender non-
planarity, as a result of Cu(d)–corrole(p) orbital interac-
tions.[24b] The saddling for pyrimidinylcorrole 7c, defined as
the average angle between the mean planes of opposite pyr-
role rings, has been determined to be 13.48 in one species
and 12.28 for the second independent corrole (Fig-
ACHTUNGTRENNUNG
ure 1).[23a,c,e,f,24] The meso substituents are approaching per-
pendicular positions with respect to the mean plane through
the four pyrrolic subunits (75.68 for the pyrimidinyl moiety
in one entity, 69.28 in the other, and an angle ranging from
77.5 to 82.18 for the mesityl units). The introduced 4-tert-bu-
tylphenoxy substituents of 7c are oriented to the opposite
side with respect to the corrolato macrocyclic plane.
Absorption spectra and photophysical properties: The broad
scope of smooth modifications of the AB2-pyrimidinylcor-
role periphery allows fine-tuning and optimization of certain
corrole properties towards application needs. Fine-tuning of
the electrochemical and photophysical features is, for in-
stance, important if one desires to use corrole-based materi-
als (as alternatives for traditional porphyrins) as active (bio-
mimetic) photosensitizers in molecular devices exploiting
sunlight.[2c] Photophysical properties of corroles are particu-
larly interesting; it has been stated that the fluorescence in-
tensities (F) of Fb–corroles are generally larger than those
of porphyrins and other related macrocycles, whereas the
(Q-band) absorption coefficients in the visible range are
also overall higher than for porphyrins.[2c,d,29] In this work,
we have examined the photophysical features of a number
of Fb pyrimidinylcorroles upon changing the substitution
pattern. The representative compounds for which the ab-
sorption spectra and luminescence properties have been in-
vestigated are gathered in Scheme 9. Experiments in fluid
solution at RT have been performed in acetonitrile and di-
chloromethane, whereas experiments at 77 K were done
using a toluene rigid matrix. The metalated Cu–, Co–, and
Ag–corroles reported in this paper did not exhibit any lumi-
nescence under the applied experimental conditions.
Scheme 9. Overview of pyrimidinylcorroles, the photophysical properties
of which have been investigated in detail.
Figure 2. Absorption spectra of 4b in dichloromethane (c) and aceto-
nitrile (b).
The absorption spectra of all pyrimidinylcorroles studied
are dominated by bands that can be attributed to spin-al-
lowed p–p* transitions analogous to those of porphyr-
ins,[2c,d,29,30] with intense Soret band(s) around 420 nm and
moderately intense Q bands in the range 500–700 nm. Mod-
erate splitting of the Soret band was observed (14–18 nm in
CH2Cl2, Table 1), previously described as an intrinsic proper-
ty of corroles with sterically demanding meso substi-
tuents.[29b,c] Figures 2 and 3 show the absorption spectra of
prototypical Fb–pyrimidinylcorroles 4b and 19, and Table 1
collects the relevant features of all species. It should be
noted that the absorption spectra of all pyrimidinylcorroles
studied in a specific solvent are quite similar, with only
Figure 3. Absorption spectra of 19 in dichloromethane (c) and acetoni-
trile (b).
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AB2-Corroles
FULL PAPER
Table 1. Absorption and luminescence data of selected pyrimidinylcorroles.
Corrole Absorption
Luminescence
lmax [nm][a,b] (e [mꢀ1 cmꢀ1])
lmax [nm][a]
t [ns][a,c]
298 K
F[a,c] 298 K lmax [nm]
t [ns]
298 K
77 K[d]
77 K[d]
4a
4b
4c
3
412 (107300), 428 (89000), 570 (2090), 600 (11200), 635
(3370)
412 (106100), 428 (93800), 570 (21500), 600 (11300), 635
(2940)
411 (100500), 425 (82700), 568 (21400), 600 (10500), 635
(2400)
415 (126800), 570 (25000), 608 (13100)
609 (sh), 647
2.4 (2.5)
2.3 (2.3)
2.3 (2.3)
0.8 (1.0)
5.6 (5.7)
4.9 (4.6)
0.066
(0.021)
0.050
(0.022)
0.053
(0.014)
0.020
(0.015)
0.152
(0.164)
0.098
600
597
598
601
602
600
2.5
609 (sh), 647
614 (sh), 649
620 (sh), 650
615 (sh), 650
606 (sh), 644
2.4
2.0
1.4
19
22
410 (102100), 428 (91700), 571 (19300), 605 (10700), 637
(4200)
410 (103000), 428 (90000), 570 (21300), 603 (10500), 634
(3100)
12.0
7.0
(0.100)
[a] Air-equilibrated dichloromethane. [b] 298 K. [c] Data in parentheses are in air-equilibrated acetonitrile. [d] Toluene rigid matrix.
minor changes in the molar absorption values. However, a
clear solvent dependence has been observed. Besides some
redshift in the Soret bands upon passing from nonpolar to
more polar solvents, the main effects of such a solvent de-
pendence of the absorption spectra are changes in the rela-
tive intensities of the various contributions to the Q-band
region, with the lowest-energy absorption feature increasing
in molar absorbtivity upon increasing the polarity of the sol-
vent (compare spectra in Figures 2 and 3). Solvent depen-
ACHTUNGTRENNUNGdence of absorption spectra of Fb–corroles has been attrib-
Figure 5. Emission spectra of 19 in dichloromethane fluid solution at RT
(b) and toluene rigid matrix at 77 K (c).
uted to perturbations due to hydrogen bonding between an
[29a]
ꢀ
internal N H group and solvent molecules,
which clearly
is enhanced in polar solvents such as acetonitrile. Our re-
sults are in line with such an attribution.
By analysis of the luminescence spectra and data, the fol-
lowing considerations can be made:
All the corroles examined exhibit a relatively intense,
structured emission in any solvent and at every temperature
condition, which in all cases decays within the nanosecond
timescale. Figures 4 and 5 show representative luminescence
spectra and the relevant data are again gathered in Table 1.
The luminescence properties are independent of the excita-
tion wavelength, both exciting in the Soret band (in the
range 380–410 nm) and in the Q bands (520–560 nm range).
On the basis of emission energy, lifetimes, and spectral
shapes, as well as by comparison with literature data,[2,29–31]
the emission is assigned to the lowest-lying singlet excited
state in all circumstances.
1) The luminescence spectra of all compounds are very simi-
lar in shape (see Figure S1 in the Supporting Information;
compare also with the spectra in Figures 4 and 5). They are
also structured, with the highest energy feature not changing
significantly on passing from RT fluid solution to a 77 K
rigid matrix (Table 1 and Figures 4 and 5), although the rela-
tive intensity of such a feature with respect to the lower-
energy features is greatly enhanced on passing to low tem-
perature. Corrected excitation spectra overlap with absorp-
tion spectra.
These results indicate that the nature of the emitting level
does not change upon passing from RT to 77 K and is also
constant within the series of solvents. Moreover, the geome-
try of the emitting excited state, populated with identical ef-
ficiency from any upper-lying excited state (as shown by the
excitation spectra), is weakly distorted in comparison to the
ground state and its energy is not significantly affected by
changing the substituents on the pyrimidinyl ring (compare
data of 4a–c) or the other meso-aryl moieties (compare data
of 3 and 4a).
2) The luminescence quantum yields (Table 1) are slightly
larger in less polar solvents (e.g., dichloromethane) than in
the more polar solvent acetonitrile (with the exception of 19
Figure 4. Emission spectra of 4b in dichloromethane fluid solution at RT
(b) and toluene rigid matrix at 77 K (c).
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F. Puntoriero, W. Dehaen, W. Maes et al.
and 22). Regardless of the solvent, luminescence quantum
yields of 19 and 22 are significantly larger than those of the
other species. The difference is about one order of magni-
tude in acetonitrile and slightly smaller in less polar sol-
vents. Compounds 4a–c exhibit approximately the same
emission quantum yield in all solvents. Differences in lumi-
nescence lifetimes (Table 1) qualitatively agree with quan-
tum yield data, with a longer luminescence lifetime for cor-
roles 19 and 22 relative to the other pyrimidinylcorroles. Lu-
minescence lifetimes do not change significantly with sol-
vent polarity (Table 1). It can also be noted that the quan-
tum yields of most of the compounds are lower than 0.1,
atypically low in comparison with literature data,[2,29–31]
which usually report emission quantum yields in the range
0.1–0.5 for Fb–corroles.
These data suggest that in the pyrimidinylcorrole species
investigated here another excited level, besides the emitting
level, is involved in determining the excited-state properties.
We propose that such a level is a state with partial charge-
transfer (CT) character and involves the pyrimidine ring as
the acceptor. This state could lead to photoinduced elec-
tron-transfer quenching of the p–p* emissive state or could
mix with the emitting state: in both cases, the result would
be an acceleration of the nonradiative rate constant, that is,
reduced emission quantum yields.
Actually, pyrimidine has low-lying p* empty orbitals, so
pyrimidine-containing moieties are often involved as accept-
or units in CT processes.[32] In the compounds studied here
it can therefore be reasonable that a CT state that involves
the corrole ring as the donor subunit—it is known that cor-
roles are able to play the role of electron donor in charge-
separated processes[33] and, in general, to be oxidized at rela-
tively mild potentials[34]—and the pyrimidinyl group as the
acceptor can lie at a similar energy as the emitting p–p* cor-
role-based excited state and contribute to deactivation of
the excited state by means of nonradiative processes, even
without perturbing the luminescence spectra. In fact, upper-
lying states can have an effect on the dynamic properties of
lower-lying excited states, even in the absence of sizeable
perturbation of excited-state level energies.[35–37] This line of
reasoning also justifies the larger quantum yields (and
longer emission lifetime) of 19 and 22 in comparison with
the other corroles studied. The two phenoxy substituents on
the pyrimidinyl moiety in 19 are electron-donor substituents
and therefore make reduction of the pyrimidinyl group
more difficult, thus destabilizing the CT state, which hence
does not contribute (to such a large extent) to the dynamic
properties of the emitting p–p* corrole level in such a spe-
cies. The pyrimidinyl moiety in monosubstituted corrole 22
bears one phenoxy and one chlorine group. Apparently, the
presence of the phenoxy substituent is dominant, so that the
behavior of 22 is similar to that of 19 as far as the photo-
physical properties are concerned. The decrease of the
quantum yield of all corroles except 19 and 22 upon passing
from less polar solvents to acetonitrile is also in line with
the presence of a CT state: acetonitrile can stabilize the CT
state, which becomes lower in energy so that its contribution
to the nonradiative processes of the emitting state can in-
crease accordingly. The fact that this does not take place for
the species containing phenoxy-substituted pyrimidinyl
groups, the luminescence quantum yields of which are sub-
stantially unaffected by the solvent (Table 1), further con-
firms that the CT state is not significantly involved in the
decay process for such compounds. It should also be recalled
that the presence of CT states has already been assumed
before to explain the reduced emission quantum yield of
corroles that contain acceptor substituents (e.g., nitro
groups).[29a,31]
The roughly identical emission lifetimes and quantum
yields of 4a–c indicate that the presence of a thiomethyl or
phenyl substituent on the 2-position of the pyrimidinyl
moiety does not have any influence on the photophysical
properties of the pyrimidinylcorroles. In fact, such substitu-
ents are expected to be almost neutral from an electronic
viewpoint, so their effect on the CT-state energy is negligi-
ble. On the contrary, compound 3 exhibits shorter emission
lifetimes and lower emission quantum yields compared to
AB2-corrole 4a. As it has been reported that the decrease
of planarity of the corrole ring because of steric hindrance
usually translates into reduced luminescence performance,[31]
the diminished luminescence of 3 compared with 4a might
be attributed to distortion of the corrole ring, as a conse-
quence of steric hindrance imposed by the chlorine substitu-
ents.
3) The 77 K emission lifetimes of all compounds except 19
(and, to a minor extent, 22) are quite close to the corre-
sponding values recorded at RT. This is indeed quite
common for corroles, the emission lifetimes of which are
usually only weakly dependent on temperature,[2c,31] but it is
not expected to be the case for the Fb–pyrimidinylcorroles
4a–c and 3 studied here, for which a CT state is assumed to
partially quench the RT luminescence. In fact, in the event
that the emissive state was a “pure” p–p* corrole-based flu-
orescent level and the CT state behaves as a quencher of
the emissive state by photoinduced electron transfer, this
quenching effect should be inefficient at 77 K, at which elec-
tron-transfer processes are usually slowed down by nuclear
barriers,[38] and longer emission lifetimes should be found at
77 K. This is indeed what has been reported for the lumines-
cence properties of nitrophenyl-substituted corroles.[31] The
small temperature dependence of the emission lifetimes of
4a–c and 3 in this case seems to indicate that the emitting
state of such compounds is better described as a mixed state
between the common p–p* corrole-based fluorescent level
and a state with partial CT character. Finally, it can also be
noted that the emission lifetimes of 19 and 22 are signifi-
cantly longer at 77 K than at RT. We suggest that the
(bulky) phenoxy substituents of the pyrimidinyl group in 19
and 22 can deactivate vibrational modes at 77 K that play
some role in the nonradiative decay process operating at
RT.
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AB2-Corroles
FULL PAPER
meso-Pyrimidinyl-substituted AB2-corroles 4a–d (general procedure 1):
5-Mesityldipyrromethane (2b) (0.750 g, 2.84 mmol) and the appropriate
2-substituted 4,6-dichloropyrimidine-5-carbaldehyde 1a–d (2.84 mmol)
were added to stirred CH2Cl2 (1 L), purged with Ar for 15 min, immedi-
ately followed by the addition of the suitable amount of BF3·OEt2
(mostly 0.043 equiv),[15] and the resulting solution was stirred at RT for
1 h (under Ar and protected from light). p-Chloranil (0.698 g, 2.84 mmol)
was subsequently added and the mixture was heated at reflux for 1 h.
The solvent was evaporated and the products were separated and puri-
fied by column chromatography (silica) to afford AB2-corroles 4a–d and
the corresponding A2B2-porphyrin analogues as purple solids.
Conclusion
In conclusion, we have demonstrated that AB2-pyrimidinyl-
corroles represent attractive corrole scaffolds towards inno-
vative corrole materials for applications. The broad scope of
(post-macrocyclization) substitution possibilities of the pyri-
midinylcorrole macrocycle, as demonstrated by SNAr, SEAr,
and Pd-catalyzed cross-coupling reactions, allows facile and
efficient access to a diversity of (elusive) functional Cu–cor-
roles hitherto unprecedented in synthetic corrole chemistry.
A further advantage is the fact that sophisticated functional-
ized free-base pyrimidinylcorroles are also readily accessible
by a smooth reductive demetalation pathway. For a series of
representative free-base AB2-pyrimidinylcorroles, the ab-
sorption spectra and luminescence features have been stud-
ied. The results showed that the photophysical properties of
the studied compounds are governed by the lowest-lying p–
p* singlet state; for a few corroles, a state with partial
charge-transfer character (from the corrole to the meso-pyri-
midinyl moiety), which contributes to the dynamic proper-
ties of the emissive levels, is plausible. Further studies will
be directed towards the construction of photoactive multi-
chromophoric arrays based on meso-pyrimidinyl-substituted
(metallo)corroles and their possible incorporation in real de-
vices that exploit sunlight, an area of particular economical
and environmental appeal to date.
Corrole 24: Synthesis according to general procedure 1. Eluent CH2Cl2/
petroleum ether 1:1. Yield: 3%. 1H NMR (300 MHz, CDCl3, 258C,
TMS): d=9.13 (s, 1H; Hpyrim), 9.10 (d, J
ACHTUNGRTEN(NGNU H,H)=4.6 Hz, 2H; Hb), 8.76 (d,
J
A
C
ACHTUNGTRENNUNG
(100 MHz, CDCl3, 258C, TMS): d=164.6, 164.2, 158.1 (CH), 141.2, 141.0,
134.7, 134.2, 130.5, 127.9, 125.6, 121.7, 117.5, 113.7 (br), 102.2, 98.5 ppm;
MS (ESI+): m/z: calcd for C35H12Cl2F10N6: 776.0; found: 779.6 [M+H]+.
General procedure for the Cu insertion in Fb–meso-triarylcorroles (gen-
eral procedure 2): Anhydrous CuACHTNUTRGENNG(U OAc)2 (54 mg, 0.3 mmol, 3 equiv) was
added to a solution of the respective Fb–corrole (0.1 mmol) in THF
(15 mL), and the mixture was stirred at RT under Ar for 10 min. THF
was removed under reduced pressure and the Cu–corroles were obtained
in pure form as brown-red solids after flash column chromatography
(silica, eluent CH2Cl2/heptane mixtures).
Nucleophilic aromatic substitution
Monosubstituted Cu–corrole 7b: A mixture of Cu–corrole 5b (26 mg,
33 mmol, 1 equiv), 4-tert-butylphenol (19.8 mg, 132 mmol, 4 equiv), finely
ground K2CO3 (27.3 mg, 198 mmol, 6 equiv), and [18]crown-6 (3 mg,
29 mmol) in dry DMF (5 mL) was heated overnight at 908C under an Ar
atmosphere. Diethyl ether (20 mL) was added to the resulting cooled
mixture, and the mixture was washed with distilled water (3ꢄ20 mL).
The organic layer was subsequently dried over MgSO4, filtered, and
evaporated to dryness. After column chromatographic purification
(eluent CH2Cl2/heptane 1:1), monosubstituted corrole 7b (21 mg, 71%)
was obtained as a red-brown solid (2.3 mg (9%) of starting corrole 5b
was recovered). 1H NMR (400 MHz, CDCl3, 258C, TMS): d=7.99 (brs,
2H; Hb), 7.30–7.25 (m, 6H; Hb +HPh), 7.12 (brs, 2H; Hb), 7.04 (s, 4H;
Experimental Section
General experimental methods: NMR spectra were acquired using com-
mercial instruments (Bruker Avance 300 MHz, Bruker AMX 400 MHz,
or Bruker Avance II+ 600 MHz) and chemical shifts (d) are reported in
parts per million (ppm) referenced to tetramethylsilane or residual NMR
spectroscopic solvent signals.[39] Mass spectra were run using a Thermo
Finnigan LCQ Advantage apparatus (ESI). All microwave irradiation ex-
periments were carried out using a dedicated CEM-Discover mono-mode
microwave apparatus operating at a frequency of 2.45 GHz and using
sealed (aluminum–Teflon crimp-top), large (10 mL) microwave process
vials. For column chromatography, 70–230 mesh silica 60 (E. M. Merck)
was used as the stationary phase. Chemicals received from commercial
sources were used without further purification. DMF and DMSO were
dried on 4 ꢃ molecular sieves. UV/Vis absorption spectra were taken
using a Perkin–Elmer Lambda 20 (KU Leuven) or a Jasco V-560 (Uni-
versitꢀ di Messina) spectrophotometer. For steady-state luminescence
measurements, a Jobin Yvon-Spex Fluoromax 2 spectrofluorimeter was
used, equipped with a Hamamatsu R3896 photomultiplier; the spectra
were corrected for photomultiplier response using a program purchased
with the fluorimeter. For the luminescence lifetimes, an Edinburgh OB
900 time-correlated single-photon-counting spectrometer was used. As
excitation sources, a Hamamatsu PLP 2 laser diode (59 ps pulse width at
408 nm) and/or the nitrogen discharge (pulse width 2 ns at 337 nm) were
employed. Emission quantum yields for deaerated solutions were deter-
H
mesit), 6.89 (d, JACTHNGUETRN(NUG H,H)=8.6 Hz, 2H; HPh), 2.40 (s, 6H), 2.38 (s, 3H),
2.09/2.07 (2s, 12H), 1.27 ppm (s, 9H); 13C NMR (100 MHz, CDCl3, 258C,
TMS): d=172.3 (C-SMe), 150.1, 148.8, 148.7, 144.0, 139.0, 137.8 132.5
(CH), 128.4/128.3 (CH), 126.1 (CH), 121.1/121.0 (CH), 34.6, 31.5 (CH3),
29.3 (CH3), 20.0 (CH3), 14.4 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=
263 (4.65), 402 (4.95), 537 nm (3.93); MS (ESI+): m/z: calcd for
C52H46ClCuN6OS: 900.2; found: 902.4 [M+H]+.
Monosubstituted Cu–corrole 12a: A mixture of Cu–corrole 5a (30.8 mg,
41.5 mmol, 1 equiv), m-cyanophenol (5.2 mg, 43.7 mmol, 1.7 equiv),
[18]crown-6 (4.8 mg, 18 mmol), and (finely ground) K2CO3 (9.5 mg,
69 mmol, 6 equiv) in dry DMF (3 mL) was heated over 24 h at 708C
under an Ar atmosphere. DMF was evaporated under vacuum and the
resulting residue was dissolved in Et2O (20 mL), washed with aqueous
NH4Cl (20 mL) and distilled water (3ꢄ20 mL), and the organic fraction
was dried over MgSO4, filtered and evaporated to dryness. After column
chromatographic purification (silica, eluent CH2Cl2/petroleum ether 5:1),
monosubstituted corrole 12a (27.0 mg, 79%) was obtained as a red-
1
brown solid (4 mg (13%) of starting corrole 5a was recovered). H NMR
(400 MHz, CDCl3, 258C, TMS): d=8.65 (s, 1H; Hpyrim), 8.02 (brs, 2H;
mined using the optically diluted method, with [RuACTHNUTRGNEUNG
(bpy)3]2+ in air-equili-
Hb), 7.51 (dt, J
7.34–7.31 (m, 3H), 7.29–7.24 (m, 3H), 7.05/7.04 (2s, 4H; Hmesit), 6.99 (d,
(H,H)=4.0 Hz, 2H; Hb), 2.40 (s, 6H), 2.10 (s, 6H), 2.07 ppm (s, 6H);
ACHUTGTNRNEUG(N H,H)=7.6/1.4 Hz, 1H), 7.46 (t, JACHTUNGTRENN(UGN H,H)=7.9 Hz, 1H),
brated aqueous solution (Fem =0.028) as quantum yield standard. Experi-
mental uncertainties on the absorption and luminescence data are as fol-
lows: absorption maxima, 2 nm; molar absorption, 10%; luminescence
maxima, 4 nm; luminescence lifetimes, 10%; luminescence quantum
yields, 15%.
Experimental procedures and data, and (1H/13C) NMR spectra for AB2-
pyrimidinylcorroles 3, 4a–d, 5a–d, 7a, 7c, 9–11,[15] and 8, 15, 19, 21[9] can
be retrieved from previous communications.
JACHTUNGTRENNUNG
13C NMR (100 MHz, CDCl3, 258C, TMS): d=157.3 (CH), 152.3, 148.7,
144.0, 139.5–138.0 (br), 137.8, 132.8 (CH), 130.5 (CH), 129.7 (CH), 128.27
(CH), 128.24 (CH), 126.7 (CH), 125.6 (CH), 121.2 (CH), 117.6, 113.6,
21.2 (CH3), 19.8 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=260 (4.485),
402 (4.858), 506 (3.859), 535 nm (3.860); MS (ESI+): m/z: calcd for
C48H35ClCuN7O: 823.2; found: 825.3 [M+H]+.
Chem. Eur. J. 2010, 16, 5691 – 5705
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5701

F. Puntoriero, W. Dehaen, W. Maes et al.
When the reaction was performed (on a similar scale) at 908C with
1.6 equiv of m-cyanophenol, monosubstituted corrole 12a was isolated in
57% yield, and the disubstituted corrole derivative 12b was also ob-
tained under these conditions in 45% yield.
Disubstituted Cu–corrole 16a: 1H NMR (300 MHz, CDCl3, 258C, TMS):
d=8.47 (s, 1H; Hpyrim), 8.00 (brs, 2H; Hb), 7.52–7.41 (m, 4H), 7.37–7.25
(m, 6H), 7.20 (d, J
ACHTNUGRTNE(NUGN H,H)=3.8 Hz, 2H; Hb), 7.05 (s, 4H; Hmesit), 6.92 (d,
JACHTUNGTRENNUNG
(H,H)=7.7 Hz, 2H), 2.41 (s, 6H), 2.08 ppm (s, 12H); 13C NMR
(150 MHz, CDCl3, 258C, TMS): d=157.3 (CH), 152.9, 151.8, 148.7, 144.0
(br), 139.0 (br), 137.9, 132.7 (CH), 132.6, 130.5 (CH), 129.5 (CH), 128.41/
128.38 (CH), 126.9 (CH), 125.8 (CH), 123.7 (CH), 121.2 (CH), 119.1,
118.0, 113.6, 21.3 (CH3), 20.0 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=
401 (4.987), 535 nm (3.973); MS (ESI+): m/z: calcd for C54H39BrCuN7O2:
959.2; found: 961.7 [M+H]+.
Disubstituted Cu–corrole 12b: Eluent gradient CH2Cl2/petroleum ether
5:1 to CH2Cl2/ethyl acetate 30:1. 1H NMR (400 MHz, CDCl3, 258C,
TMS): d=8.46 (s, 1H; Hpyrim), 8.02 (brs, 2H; Hb), 7.50 (dt, J
1.2 Hz, 2H), 7.46 (t, J(H,H)=7.8 Hz, 2H), 7.38–7.26 (m, 8H), 7.18 (d,
(H,H)=4.0 Hz, 2H; Hb), 7.05 (s, 4H; Hmesit), 2.41 (s, 6H), 2.08 ppm (s,
ACHTUNGTRENUN(NG H,H)=7.8/
ACHTUNGTRENNUNG
JACHTUNGTRENNUNG
12H); 13C NMR (100 MHz, CDCl3, 258C, TMS): d=157.2 (CH), 152.8,
148.7, 144.1, 139.5–138.5 (br), 138.0, 132.8 (CH), 130.6 (CH), 129.6 (CH),
128.4 (CH), 126.9 (CH), 125.7 (CH), 121.3 (CH), 117.9, 113.7, 21.3
(CH3), 20.0 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=402 (4.885), 505
(3.841), 536 nm (3.850); MS (ESI+): m/z: calcd for C55H39CuN8O2: 906.2;
found: 907.4 [M+H]+.
Disubstituted Cu–corrole 16b: 1H NMR (600 MHz, CDCl3, 258C, TMS):
d=8.46 (s, 1H; Hpyrim), 8.00 (brs, 2H; Hb), 7.44 (d, J
7.32 (brd, J(H,H)=3.0 Hz, 2H; Hb), 7.29 (brs, 2H; Hb), 7.05 (s, 4H;
mesit), 6.91 (d, J(H,H)=9.1 Hz, 4H), 2.41 (s, 6H), 2.07 ppm (s, 12H);
ACHTUNGTREN(NUGN H,H)=9.1 Hz, 4H),
AHCTUNGTRENNUNG
H
ACHTUNGTRENNUNG
13C NMR (150 MHz, CDCl3, 258C, TMS): d=157.4 (CH), 151.8, 148.7,
137.9, 132.7 (CH), 128.4 (CH), 123.7 (CH), 121.1 (CH), 119.0, 21.3
(CH3), 20.0 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=402 (5.167),
536 nm (4.137); MS (ESI+): m/z: calcd for C53H39Br2CuN6O2: 1012.1;
found: 1014.7 [M+H]+.
Monosubstituted Cu–corrole 13: A mixture of Cu–corrole 5a (23.7 mg,
31.9 mmol, 1 equiv), 4-chlorothiophenol (15.6 mg, 108 mmol, 3.4 equiv),
[18]crown-6 (4.8 mg, 18 mmol), and (finely ground) K2CO3 (17.5 mg,
127 mmol, 4 equiv) in dry DMF (3 mL) was heated over 20 h at 908C
under an Ar atmosphere. DMF was evaporated under vacuum and the
resulting residue was dissolved in Et2O (20 mL), washed with aqueous
NH4Cl (20 mL) and distilled water (3ꢄ20 mL), and the organic fraction
was dried over MgSO4, filtered, and evaporated to dryness. After column
chromatographic purification (silica, eluent CH2Cl2/heptane 1:1), mono-
substituted corrole 13 (21.9 mg, 81%) was obtained as a red-brown solid
(1 mg (4%) of starting corrole 5a was recovered). 1H NMR (400 MHz,
CDCl3, 258C, TMS): d=8.69 (s, 1H; Hpyrim), 8.00 (brs, 2H; Hb), 7.37–7.30
Monosubstituted Cu–corrole 16c: 1H NMR (400 MHz, CDCl3, 258C,
TMS): d=8.64 (s, 1H; Hpyrim), 8.02 (brs, 2H; Hb), 7.45 (d, J
8.8 Hz, 2H), 7.32 (d, J(H,H)=3.5 Hz, 2H; Hb), 7.26 (brs, 2H; Hb), 7.04
(2s, 4H; Hmesit), 7.00 (d, J(H,H)=4.0 Hz, 2H; Hb), 6.88 (d, J(H,H)=
ACHTUNGTRENNUNG(H,H)=
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
8.8 Hz, 2H), 2.40 (s, 6H), 2.10 (s, 6H), 2.06 ppm (s, 6H); 13C NMR
(150 MHz, CDCl3, 258C, TMS): d=157.6 (CH), 151.4, 148.8, 137.9, 132.8
(CH), 128.41/128.35 (CH), 123.7 (CH), 121.3 (CH), 119.4, 21.3 (CH3),
19.98/19.96 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=402 (5.404), 506
(4.363), 535 nm (4.371); MS (ESI+): m/z: calcd for C47H35BrClCuN6O:
876.1; found: 878.2 [M+H]+.
(m, 6H), 7.23 (brs, 2H; Hb), 7.04 (s, 4H; Hmesit), 6.94 (d, JACTHNUGTRNEUNG(H,H)=3.8 Hz,
2H; Hb), 2.40 (s, 6H), 2.11 (s, 6H), 2.09 ppm (s, 6H); 13C NMR
(100 MHz, CDCl3, 258C, TMS): d=157.3 (CH), 149.1, 144.3, 138.8 (br),
137.9, 136.9 (CH), 136.4, 133.0 (CH), 129.6 (CH), 128.42/128.37 (CH),
126.6, 121.3 (CH), 21.3 (CH3), 20.03/19.96 ppm (CH3); UV/Vis (CH2Cl2):
lmax (loge)=266 (4.564), 406 (4.913), 538 nm (3.896); MS (ESI+): m/z:
calcd for C47H35Cl2CuN6S: 848.1; found: 850.4 [M+H]+.
Asymmetric disubstitution by tandem Suzuki–SNAr reaction: Aqueous
Na2CO3 (2m, 0.1 mL) was added to a mixture of Cu–corrole 5a (16.0 mg,
21.6 mmol, 1 equiv), phenylboronic acid (8 mg, 65.6 mmol, 3 equiv), and
[PdACHTNUGRTNEUNG(PPh3)4] (1 mg, 4 mol%) in toluene (3 mL), and the resulting mixture
was heated by microwave irradiation at 1008C (100 W) for 1 h. After
cooling to RT, the solvent was evaporated under vacuum and the residue
was redissolved in CH2Cl2 (20 mL), washed with distilled water (3ꢄ
20 mL), and the organic layer was dried over MgSO4 and filtered. The
solvent was evaporated under vacuum and the monosubstituted corrole
was separated from the remaining starting material (36%) and traces of
the disubstituted derivative by flash column chromatography (silica,
eluent CH2Cl2). Dry DMF (5 mL) was added to a round-bottom flask
that contained the monosubstituted Cu–corrole, 4-tert-butylphenol
(13 mg, 86 mmol), [18]crown-6 (2 mg, 8 mmol), and (finely ground) K2CO3
(15 mg, 109 mmol), and the resulting mixture was heated by microwave ir-
radiation at 1758C (100 W) over 1 h. DMF was evaporated under
vacuum and the resulting residue was dissolved in Et2O (20 mL), washed
with aqueous NH4Cl (20 mL) and distilled water (3ꢄ20 mL), and the or-
ganic fraction was dried over MgSO4, filtered, and evaporated to dryness.
After column chromatographic purification (silica, eluent CH2Cl2/hep-
tane 7:3), asymmetrically disubstituted Cu–corrole 17 (6.6 mg, 34%) was
obtained as a red-brown solid. 1H NMR (400 MHz, CDCl3, 258C, TMS):
d=8.94 (s, 1H; Hpyrim), 7.97 (brs, 2H; Hb), 7.57–7.51 (m, 2H; Hb), 7.37–
Disubstituted Cu–corrole 14: A mixture of Cu–corrole 5a (25.0 mg,
33.7 mmol, 1 equiv), p-dodecylphenol (50 mg, 191 mmol, 5.6 equiv), and
Cs2CO3 (88 mg, 269 mmol, 8 equiv) in dry DMF (3 mL) was heated over
48 h at 1208C under an Ar atmosphere. DMF was evaporated under
vacuum and the resulting residue was dissolved in Et2O (20 mL), washed
with aqueous NH4Cl (20 mL) and distilled water (3ꢄ20 mL), and the or-
ganic fraction was dried over MgSO4, filtered, and evaporated to dryness.
After column chromatographic purification (silica, eluent CH2Cl2/petrole-
um ether 1:1), disubstituted corrole 14 (32.6 mg, 81%) was obtained as a
red-brown film. 1H NMR (400 MHz, CDCl3, 558C, TMS): d=8.47 (brs,
1H), 8.25 (brs, 2H), 7.54 (brs, 2H), 7.34–7.15 (m, 12H), 7.00–6.95 (m,
4H), 2.46 (s, 6H), 2.17 (s, 12H), 1.75–0.60 ppm (m, 50H); 13C NMR
(100 MHz, CDCl3, 258C, TMS): d=157.6 (CH), 150.5, 148.6, 147.1, 143.7,
139.3 (br), 137.7, 132.5 (CH), 128.3 (CH), 127.6 (CH), 128.0–127.0 (br,
CH), 127.0 (CH), 121.04/120.97/120.81 (CH), 40.9 (CH2), 37.6 (CH2), 29.4
(CH2), 29.1 (CH2), 21.3 (CH3), 20.0 (CH3), 8.9 ppm (CH3); UV/Vis
(CH2Cl2): lmax (loge)=402 (4.886), 510 (3.853), 538 nm (3.886); MS
(ESI+): m/z: calcd for C77H89CuN6O2: 1192.6; found: 1193.4 [M+H]+.
Due to their modest intensity and the presence of solvent impurities (pe-
troleum ether), the C signals for the dodecyl chains could not be identi-
fied unambiguously.
7.31 (m, 4H), 7.20–7.10 (m, 7H), 7.01 (s, 4H; Hmesit), 6.94 (d, JACHTUNGTRENNUNG(H,H)=
8.6 Hz, 2H), 2.39 (s, 6H), 2.04 (s, 6H), 1.98 (s, 6H), 1.29 ppm (s, 9H);
13C NMR (100 MHz, CDCl3, 258C, TMS): d=158.0 (CH), 150.4, 148.5,
145.0–143.0 (br), 137.8, 132.0 (CH), 129.5 (CH), 128.5 (CH), 128.34/
128.28 (CH), 126.5 (CH), 121.1/121.0 (CH), 34.6, 31.5 (CH3), 21.3 (CH3),
20.0 (CH3), 19.8 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=263 (4.664),
407 (4.870), 540 nm (3.973); MS (ESI+): m/z: calcd for C57H49CuN6O:
896.3; found: 897.9 [M+H]+.
Asymmetric disubstitution by double SNAr reaction: A mixture of mono-
substituted Cu–corrole 12a (17.5 mg, 21.2 mmol, 1 equiv), p-bromophenol
(14.3 mg, 82.7 mmol, 3.9 equiv), [18]crown-6 (4.8 mg, 18 mmol), and (finely
ground) K2CO3 (18.6 mg, 135 mmol) in dry DMF (3 mL) was heated over
20 h at 908C under an Ar atmosphere, and subsequently the temperature
was elevated to 1208C (since some starting material remained) and the
reaction was continued for another 28 h. DMF was evaporated under
vacuum and the resulting residue was dissolved in Et2O (20 mL), washed
with aqueous NH4Cl (20 mL) and distilled water (3ꢄ20 mL), and the or-
ganic fraction was dried over MgSO4, filtered, and evaporated to dryness.
After column chromatographic purification (silica, eluent CH2Cl2/hep-
tane 1:1), three main corroles 16a (5.7 mg, 28%), 16b (4.6 mg, 21%),
and 16c (3.7 mg, 20%) were obtained.
Monosubstituted Cu–corrole 18a: Aqueous Na2CO3 (2m, 0.1 mL) was
added to a mixture of Cu–corrole 5b (25.0 mg, 31.7 mmol, 1 equiv), phe-
nylboronic acid (7.7 mg, 63.2 mmol, 2 equiv), and [PdACTHNUTRGNE(UNG PPh3)4] (1.8 mg,
5 mol%) in toluene (3 mL), and the resulting mixture was heated by mi-
crowave irradiation at 1208C (100 W) for 2 h. After cooling to RT, the
solvent was evaporated under vacuum and the residue was redissolved in
Et2O (20 mL), washed with distilled water (3ꢄ20 mL), and the organic
layer was dried over MgSO4 and filtered. The solvent was evaporated
5702
www.chemeurj.org
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 5691 – 5705

AB2-Corroles
FULL PAPER
under vacuum and, after purification by column chromatography (silica,
eluent CH2Cl2/heptane 2:3), monosubstituted corrole 18a (20.1 mg, 79%)
was obtained as a red-brown solid. 1H NMR (400 MHz, CDCl3, 258C,
General procedure for the demetalation of Cu–meso-triarylcorroles (gen-
eral procedure 3): SnCl2·2H2O (113 mg, 0.5 mmol, 10 equiv) was added
to a solution of the respective Cu–corrole (0.05 mmol) in acetonitrile/di-
chloromethane (2:1; 15 mL), and the resulting mixture was stirred for
10 min at RT under Ar. Subsequently, concentrated aqueous HCl (1 mL)
was added and stirring was continued for 10 min at RT under Ar. The
completion of the demetalation process was monitored by ESIMS and
TLC. The mixture was diluted with diethyl ether, washed with water till
neutral, dried over Na2SO4, and the drying agent was filtered off. The sol-
vent was evaporated under reduced pressure and the pure free-base cor-
roles were obtained as purple solids after flash column chromatography
(silica).
TMS): d=7.96 (brs, 2H; Hb), 7.49 (d, J
ACHTUGNTRENN(UNG H,H)=7.0 Hz, 2H; HPh), 7.35 (d,
JACHTUNGTRENNUNG(H,H)=3.8 Hz, 2H; Hb), 7.19–7.10 (m, 5H; HPh +Hb), 7.00–6.99 (m,
6H; Hmesit +Hb), 2.69 (s, 3H), 2.38 (s, 6H), 2.05/1.96 ppm (2s, 12H);
13C NMR (100 MHz, CDCl3, 258C, TMS): d=172.6 (C-SMe), 149.4,
144.3/144.1, 138.5/138.4, 137.9/137.3 (CH), 132.1 (CH), 130.0 (CH), 128.4/
128.2 (CH), 121.2, 21.3 (CH3), 20.0/19.8 (CH3), 14.7 ppm (CH3); UV/Vis
(CH2Cl2): lmax (loge)=265 (4.185), 407 (4.345), 540 nm (3.373); MS
(ESI+): m/z: calcd for C48H38ClCuN6S: 828.2; found: 829.3 [M+H]+.
Disubstituted Cu–corrole 18b: A mixture of Cu–corrole 18a (12.8 mg,
15 mmol, 1 equiv), 4-tert-butylphenol (9.2 mg, 60 mmol, 4 equiv), finely
ground K2CO3 (12.7 mg, 90 mmol, 6 equiv), and [18]crown-6 (3 mg,
60 mmol) in dry DMF (5 mL) was heated by microwave irradiation at
1758C (150 W) for 1 h. Et2O (20 mL) was added to the resulting mixture,
and the mixture was washed with distilled water (3ꢄ20 mL), dried over
MgSO4, filtered, and evaporated to dryness. After column chromato-
graphic purification (silica, eluent CH2Cl2/heptane 2:3), disubstituted cor-
role 18b (10.6 mg, 76%) was obtained as a red-brown solid. 1H NMR
Corrole 22: According to general procedure 3: monosubstituted Cu–cor-
role 7b (20 mg, 22 mmol), SnCl2·2H2O (20 mg, 89 mmol), MeCN/CH2Cl2
(2:1; 15 mL), concentrated HCl (1 mL), eluent CH2Cl2/heptane 2:1.
Yield: 98% (18.3 mg). 1H NMR (400 MHz, CDCl3, 258C, TMS): d=8.79
(d, J
(H,H)=4.8 Hz, 2H; Hb), 8.26 (d, J
(2s, 4H; Hmesit), 7.17 (d, J(H,H)=8.8 Hz, 2H; HPh), 6.84 (d, JACHTUNGTRENNUNG
A
ACHTUNGRTEN(NGNU H,H)=4.8 Hz, 2H; Hb), 8.46 (d,
J
N
ACHTUNGTRENNUNG
E
8.6 Hz, 2H; HPh), 2.59 (s, 6H), 2.52 (s, 3H), 1.94/1.91 (2s, 12H), 1.18 ppm
(s, 9H); 13C NMR (100 MHz, CDCl3, 258C, TMS): d=171.9, 169.3, 163.5,
150.3, 148.4, 139.4/139.3, 137.9, 135.5, 134.6, 129.5, 128.2 (br; CH), 125.9
(CH), 124.7 (CH), 121.0 (CH), 116.4, 114.8 (CH), 97.5, 34.5, 31.4 (CH3),
21.6/21.3 (CH3), 14.5 ppm (CH3); UV/Vis (CH2Cl2): lmax (loge)=410
(5.013), 428 (4.954), 570 (4.328), 603 (4.021), 634 nm (3.491); MS (ESI+):
m/z: calcd for C52H49ClN6OS: 840.3; found: 842.0 [M+H]+.
(400 MHz, CDCl3, 258C, TMS): d=7.94 (brs, 2H; Hb), 7.52 (d, J
7.5 Hz, 2H; HPh), 7.28 (d, J(H,H)=8.8 Hz, 2H; HPh), 7.19 (d, J
4.0 Hz, 2H; Hb), 7.14–7.11 (m, 5H; HPh), 7.00 (2s, 4H; Hmesit), 6.93 (d,
(H,H)=8.7 Hz, 4H; HPh), 2.44 (s, 3H), 2.39 (s, 6H), 2.04/1.97 (2s, 12H),
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
JACHTUNGTRENNUNG
1.28 ppm (s, 9H); 13C NMR (100 MHz, CDCl3, 258C, TMS): d=171.7 (C-
SMe), 150.4, 149.3, 148.2, 143.9, 138.5, 137.9/137.8, 131.6 (CH), 129.4
(CH), 128.6 (CH), 128.3/128.1 (CH), 125.9 (CH), 121.3 (CH), 120.9 (CH),
34.6, 31.6 (CH3), 21.3 (CH3), 20.0/19.8 (CH3), 14.3 ppm (CH3); UV/Vis
(CH2Cl2): lmax (loge)=260 (5.672), 405 (5.803), 510 (4.845), 540 nm
(4.858); MS (ESI+): m/z: calcd for C58H51CuN6OS: 942.3; found: 943.5
[M+H]+.
Corrole 23: According to general procedure 3: asymmetrically disubsti-
tuted Cu–corrole 17 (10 mg, 11 mmol), SnCl2·2H2O (10 mg, 44 mmol),
MeCN/CH2Cl2 (2:1; 15 mL), concentrated HCl (1 mL), eluent CH2Cl2.
Yield: 84% (7.8 mg). 1H NMR (400 MHz, CDCl3, 258C, TMS): d=9.21
(s, 1H; Hpyrim), 8.79 (d, J
8.24 (d, J(H,H)=4.0 Hz, 2H; Hb), 7.27–7.20 (m, 8H), 6.88 (d, J
6.8 Hz, 2H), 6.68 (t, J(H,H)=7.3 Hz, 1H), 6.59 (t, J(H,H)=7.7 Hz, 2H),
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
Suzuki cross-coupling on Fb–AB2-pyrimidinylcorrole 4a: Phenylboronic
acid (41 mg, 0.34 mmol, 3 equiv) was added to a mixture of Fb–AB2-cor-
A
ACHTUNGTRENNUNG
2.58 (s, 6H), 1.96 (s, 6H), 1.79 (s, 6H), 1.19 (s, 9H), ꢀ0.75–2.5 ppm (brs,
3H; NH); 13C NMR (100 MHz, CDCl3, 258C, TMS): d=170.2, 158.0
(CH), 150.5, 148.2, 139.4, 139.2, 138.6, 137.9, 135.5, 129.1 (CH), 128.3/
128.2 (CH), 127.7/127.6 (CH), 126.4 (CH), 124.7 (CH), 121.0/120.9/120.7
(CH), 115.1 (CH), 34.5, 31.5 (CH3), 21.5 (CH3), 21.4 (CH3), 21.1 ppm
(CH3); UV/Vis (CH2Cl2): lmax (loge)=281 (3.806), 412 (5.037), 427
(4.952), 569 (4.238), 604 (4.033), 636 nm (3.690); MS (ESI+): m/z: calcd
for C57H52N6O: 836.4; found: 838.6 [M+H]+.
role 4a (76 mg, 0.11 mmol, 1 equiv) and [PdACHTNUTRGNE(UNG PPh3)4] (4 mg, 3.5 mmol) in
toluene (6 mL) under Ar, immediately followed by the addition of aque-
ous Na2CO3 (2m, 0.75 mL), and the mixture was heated at reflux for 24 h
under an Ar atmosphere. After cooling to RT, the solvent was evaporat-
ed under vacuum and the residue was redissolved in CH2Cl2 (20 mL),
washed with distilled water (3ꢄ20 mL), and the organic layer was dried
over MgSO4 and filtered. The solvent was evaporated under vacuum and
the crude corrole mixture was separated by column chromatography
(silica, eluent CH2Cl2), thereby affording monosubstituted pyrimidinyl-
corrole 20a (50 mg, 62%) and the disubstituted congener 20b (25 mg,
29%) as purple-greenish solids.
Pyrimidinylcorrole metalation reactions
CoIII
tion of the procedures described by Gross and Guilard.[27] AB2-pyrimidi-
nylcorrole 4a (27.0 mg, 39.6 mmol) and anhydrous [Co(acac)2] (acac=
ACHTUNGRTEN(NUGN PPh3)–corrole 25: Co-insertion procedure according to a combina-
Monosubstituted pyrimidinylcorrole 20a: 1H NMR (400 MHz, CDCl3,
AHCTUNGTRENNUNG
258C, TMS): d=9.38 (s, 1H; Hpyrim), 8.80 (d, J
8.38 (d, J(H,H)=4.7 Hz, 2H; Hb), 8.25 (d, J(H,H)=4.1 Hz, 2H; Hb), 8.19
(d, J(H,H)=4.7 Hz, 2H; Hb), 7.24 (s, 2H; Hmesit), 7.21 (s, 2H; Hmesit), 7.17
(d, J(H,H)=7.4 Hz, 2H; Ho), 6.67 (t, J(H,H)=7.4 Hz, 1H; Hp), 6.53 (t,
ACHTUNGTREN(NGNU H,H)=4.1 Hz, 2H; Hb),
acetylacetonate; 51 mg, 198 mmol, 5 equiv) were dissolved in CH2Cl2/
EtOH (3.5:1.5 mL) and heated at reflux for 24 h; the reaction was moni-
tored by ESIMS. Subsequently, PPh3 (34 mg, 130 mmol, 3.3 equiv) was
added, and the mixture was stirred for 15 min at RT and evaporated to
dryness. The residue was passed through a silica column (eluent CH2Cl2/
G
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
E
ACHTUNGTRENNUNG
J
G
2.5 ppm (brs, 3H; NH); 13C NMR (100 MHz, CDCl3, 258C, TMS): d=
168.8, 165.1, 157.9 (CHpyrim), 142 (br; Ca), 140 (br; Ca), 139.3, 139.1,
138.1, 137.9, 135.2, 135.0, 132.9, 130.1, 128.9 (CH), 128.7 (CHb), 128.19
(CH), 128.12 (CH), 127.5 (CH), 124.2 (CHb), 121.0 (br; CHb), 115.2
(CHb), 100.3, 21.5 (CH3), 21.3 (CH3), 21.0 ppm (CH3); MS (ESI+): m/z:
calcd for C47H39ClN6: 722.3; found: 723.4 [M+H]+.
heptane 2:1), thereby affording bright red CoIII
(16.2 mg, 41%). 1H NMR (300 MHz, CDCl3, 258C, TMS): d=9.18 (s,
1H; Hpyrim), 8.17 (d, J(H,H)=4.3 Hz, 2H; Hb), 8.12 (d, J(H,H)=4.6 Hz,
2H; Hb), 8.03 (d, J(H,H)=5.5 Hz, 2H; Hb), 7.74 (d, J(H,H)=4.6 Hz,
2H; Hb), 7.06 (s, 2H; Hmesit), 7.03 (s, 2H; Hmesit), 6.98 (t, J(H,H)=7.3 Hz,
ACHTUNGRTEN(NGNU PPh3)–corrole 25
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
3H; PPh3), 6.68–6.58 (m, 6H; PPh3), 5.09–4.98 (m, 6H; PPh3), 2.49 (s,
6H), 1.67 (s, 6H), 1.32 ppm (s, 6H); 13C NMR (100 MHz, CDCl3, 258C,
TMS): d=157.6 (CH), 146.4, 144.7, 143.7, 138.0, 137.1, 136.9, 136.6, 136.3,
136.1, 131.6 (CH), 131.4 (CH), 129.8 (CH), 129.4 (CH), 127.9 (CH), 127.5
(CH), 127.4 (CH), 127.3 (CH), 123.9 (CH), 123.6, 121.9 (CH), 120.2
(CH), 21.3 (CH3), 20.3 (CH3), 19.9 ppm (CH3); UV/Vis (CH2Cl2): lmax
(loge)=381 (4.661), 410 (4.582), 532 (sh; 3.859), 572 nm (sh; 3.833); MS
(ESI+): m/z: calcd for C59H46Cl2CoN6P: 998.2; found: 998.0 [M+H]+,
736.4 [M+HꢀPPh3]+.
Disubstituted pyrimidinylcorrole 20b: 1H NMR (400 MHz, CDCl3, 258C,
TMS): d=9.70 (s, 1H; Hpyrim), 8.79 (d, J
8.19 (m, 6H; Hb), 7.21 (s, 4H; Hmesit), 7.05 (d, J
6.59 (t, J(H,H)=7.4 Hz, 2H; Hp), 6.48 (t, J(H,H)=7.4 Hz, 4H; Hm), 2.57
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
(s, 6H), 1.81 (s, 12H), ꢀ0.6–2.6 ppm (brs, 3H; NH); 13C NMR (100 MHz,
CDCl3, 258C, TMS): d=168.7, 158.3 (CHpyrim), 150.0 (br), 139.2, 139.0
(br), 137.9, 135.7 (br), 135.3, 131.7 (br), 129.2 (CHb), 128.8 (CH), 128.2
(CH), 127.9 (CH), 127.40/127.33 (CH), 127.0 (CH), 124.2 (CHb), 121.8
(br, CHb), 115.8 (CHb), 101.4, 21.5 (CH3), 21.1 ppm (CH3); UV/Vis
(CH2Cl2): lmax (loge)=417 (5.017), 431 (5.001), 572 (4.176), 607 (4.006),
642 nm (3.785); MS (ESI+): m/z: calcd for C53H44N6: 764.4; found: 765.4
[M+H]+.
AgIII–corrole 26: Ag-insertion procedure according to Brꢅckner et al.[7b]
AB2-pyrimidinylcorrole 4a (25.2 mg, 37.0 mmol) was dissolved in pyridine
(3 mL), and silver(I) acetate (20 mg, 120 mmol, 3.3 equiv) was added. The
solution was heated to 808C and kept at this temperature for 5 min. The
Chem. Eur. J. 2010, 16, 5691 – 5705
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F. Puntoriero, W. Dehaen, W. Maes et al.
reaction mixture was filtered through a plug of Celite and the solvent
was removed under vacuum. After column chromatographic purification
(silica, eluent ethyl acetate/heptane 1:4), AgIII–corrole 26 was isolated as
a dark red solid (9.3 mg, 32%). H NMR (300 MHz, CDCl3, 258C, TMS):
d=9.20 (s, 1H; Hpyrim), 9.10 (d, JACHTNUGTRENNUNG
1987–1999; c) L. Flamigni, D. T. Gryko, Chem. Soc. Rev. 2009, 38,
1635–1646; d) I. Aviv-Harel, Z. Gross, Chem. Eur. J. 2009, 15,
8382–8394.
1
[3] Reviews on (synthetic) corrole chemistry: a) D. T. Gryko, Eur. J.
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Angew. Chem. 2004, 116, 1952–1965; Angew. Chem. Int. Ed. 2004,
43, 1918–1931; d) S. Nardis, D. Monti, R. Paolesse, Mini-Rev. Org.
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J
J
N
ACHTUNGTRENNUNG
12H); 13C NMR (75 MHz, CDCl3, 258C, TMS): d=164.8, 157.9 (CH),
139.4, 138.1, 135.7, 134.2, 132.8, 129.9 (CH), 129.5, 128.2 (CH), 122.5
(CH), 119.2 (CH), 118.3 (CH), 116.9, 21.6 (CH3), 21.4 ppm (CH3); UV/
Vis (CH2Cl2): lmax (loge)=284 (4.319), 324 (4.136), 426 (5.354), 495
(3.843), 520 (4.102), 532 (4.183), 557 (4.569), 572 nm (4.648); MS (ESI+):
m/z: calcd for C41H31AgCl2N6: 784.1; found: 786.3 [M+H]+.
GaIII–corrole 27: Ga-insertion procedure according to Gross et al.[28] Dry
pyridine (7.5 mL) was added to AB2-pyrimidinylcorrole 4a (25 mg,
37 mmol) and galliumACHTUNGTRENNUNG(III) chloride (65 mg, 369 mmol, 10 equiv), and the
mixture was heated at reflux under an Ar atmosphere for 1 h. The sol-
vent was evaporated under vacuum and the residue was passed through a
silica gel column (eluent CH2Cl2/ethyl acetate gradient with 1% pyri-
dine), thereby affording GaIII–corrole 27 (5 mg, 16%) as a purple-green-
ish solid. 1H NMR (300 MHz, CDCl3, 258C, TMS): d=9.13 (s, 1H;
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716; b) J. P. Collman, A. Decrꢈau, Org. Lett. 2005, 7, 975–978; c) M.
Brçring, C. Milsmann, S. Ruck, S. Kçhler, J. Organomet. Chem.
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Brꢅckner, C. A. Barta, R. P. BriÇas, J. A. Krause Bauer, Inorg.
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Hpyrim), 8.99 (d, J
Hb), 8.54 (d, J(H,H)=4.6 Hz, 2H; Hb), 8.23 (d, J
Hb), 7.26 (s, 4H; Hmesit), 6.76 (t, J(H,H)=7.3 Hz, 1H; pyridine), 5.96–5.89
A
ACHTUNGTREN(NGNU H,H)=4.6 Hz, 2H;
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
(m, 2H; pyridine), 3.39–3.36 (m, 2H; pyridine), 2.61 (s, 6H), 1.87 ppm (s,
12H); UV/Vis (CH2Cl2): lmax (loge)=258 (3.908), 286 (3.876), 336
(3.582), 406 (sh; 4.488), 425 (4.843), 529 (3.603), 569 (3.759), 603 nm
(4.034); MS (ESI+): m/z: calcd for C46H36Cl2GaN7: 825.2; found: 788.5
[M+Kꢀpyridine]+.
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Crystallographic data for 7c: Crystallization from CHCl3/hexane;
C61H57CuN6O2; Mr =969.69; crystal dimensions 0.45ꢄ0.3ꢄ0.1 mm; triclin-
¯
ic; space group P1 (no. 2); a=13.2624(4), b=17.7902(5), c=
25.9222(6) ꢃ; V=5814.4(3) ꢃ3; Z=2; 1calcd =1.176 gcmꢀ3; m=1.516 cmꢀ1
;
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Chem. 2009, 7, 439–443.
2qmax =143.068; R1 =5.95% (I>2s(I)); 7.78% (all data) and wR2 =
15.47% (I>2s(I)); 16.58% (all data); goodness of fit: 1.023. 100119 re-
flections were measured, of which 22030 were unique. Full-matrix least-
squares refinement based on jF2 j, 1439 parameters, hydrogen atoms
were placed at calculated positions with temperature factors 20% higher
than parent atoms (50% higher for methyl groups), min./max. residual
electron density ꢀ0.331/0.756 eꢃꢀ3. The data were measured (omega and
phi scans) using a Bruker SMART 6000 detector CuKa (l=1.54178 ꢃ)
with crossed Gçbel mirrors. The crystals were cryo-cooled to 100 K. The
data were corrected for Lorentz, absorption (Bruker SADABS), and po-
larization effects. The structure was solved by direct methods. CCDC-
757471 (7c) contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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Acknowledgements
The authors thank the IWT (Institute for the Promotion of Innovation
through Science and Technology in Flanders) for a doctoral fellowship to
T.H.N., the FWO (Fund for Scientific Research—Flanders) for financial
support and a postdoctoral fellowship to W.M., and the KU Leuven and
the Ministerie voor Wetenschapsbeleid for continuing financial support.
The University of Messina (Progetti di Ricerca di Ateneo) is also ac-
knowledged for financial support.
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[17] Collman prepared
a meso-pyrimidinyl-substituted A3-corrole by
using either conventional or microwave heating: J. P. Collman, R. A.
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[18] These corroles have previously been described as A2B-pyrimidinyl-
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consistency with the analogous A2B- and A3-pyrimidinylcorroles, the
synthesis and functionalization of which has recently been disclosed
(T. H. Ngo, F. Nastasi, F. Puntoriero, S. Campagna, W. Dehaen, W.
Maes, J. Org. Chem. 2010, 75, 2127–2130), we prefer to denominate
them further on as AB2-pyrimidinylcorroles.
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Chem. Eur. J. 2010, 16, 5691 – 5705

AB2-Corroles
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Received: January 4, 2010
Published online: April 14, 2010
Chem. Eur. J. 2010, 16, 5691 – 5705
ꢂ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5705