Peripheral arylation of subporphyrazines

Article abstract of DOI:10.1002/chem.201301140

Peripherally hexaarylated subporphyrazines (SubPzs) have been prepared through a Pd-catalyzed, CuTC-mediated coupling of a hexaethylsulfanylated subporphyrazine with arylboronic acids. The introduced aryl substituents strongly influence the electronic properties of the subporphyrazine through effective conjugative interaction. Aryl rings endowed with π-electron- donating groups at the para positions produce a remarkable perturbation of the electron density of the SubPz macrocycle. This is reflected through significant redshifts of the SubPz CT and Q-bands, together with increase of the molar absorptivity of the former, with respect to those exhibited by the hexaphenyl-SubPz 2 a. Moreover, the trend in the first SubPz reduction potentials correlates with the Hammett constants (σ_p) corresponding to the para substituents of the aryl. The domed, extended SubPz π-system self-assembles in the solid state to form a dimeric capsule that houses a solvent molecule. Copyright

Full text of DOI:10.1002/chem.201301140

FULL PAPER
DOI: 10.1002/chem.201301140
Peripheral Arylation of Subporphyrazines
Tomohiro Higashino,[a, b] M. Salomꢀ Rodrꢁguez-Morgade,*[a] Atsuhiro Osuka,*[b] and
Tomꢂs Torres*[a, c]
Abstract: Peripherally hexaarylated
subporphyrazines (SubPzs) have been
positions produce a remarkable pertur-
bation of the electron density of the
SubPz macrocycle. This is reflected
through significant redshifts of the
SubPz CT and Q-bands, together with
increase of the molar absorptivity of
the former, with respect to those exhib-
ited by the hexaphenyl-SubPz 2a.
Moreover, the trend in the first SubPz
reduction potentials correlates with the
Hammett constants (sp) corresponding
to the para substituents of the aryl. The
domed, extended SubPz p-system self-
assembles in the solid state to form a
dimeric capsule that houses a solvent
molecule.
prepared through
a
Pd-catalyzed,
CuTC-mediated coupling of a hexae-
thylsulfanylated subporphyrazine with
arylboronic acids. The introduced aryl
substituents strongly influence the elec-
tronic properties of the subporphyra-
zine through effective conjugative in-
teraction. Aryl rings endowed with p-
electron-donating groups at the para
Keywords: arylation · conjugation ·
cross-coupling · electrochemistry ·
porphyrins
Introduction
SubPz macrocycle. So far, SubPzs have been prepared by
boron(III)-assisted cyclotrimetrization of maleonitrile deriv-
atives. For this reaction, the stereochemistry of the dinitrile
precursor has proven crucial. In fact, neither bis(alkyl)- or
bis(aryl)fumaronitriles afford SubPzs under the standard re-
AHCTUNGTRENNUNG
Subporphyrazines (SubPz) are aromatic porphyrinoids con-
sisting of three pyrrole subunits connected through their 2,5-
positions by aza bridges.[1] Structurally, they arise from the
formal removal of the three benzene rings from subphthalo-
cyanines (SubPcs)[2] and hence, they share some properties
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
action conditions.[1a] The only exception has been the use of
unsubstituted fumaronitrile in a mixed condensation with
tetramethylsuccinonitrile. This gave a mixture of a subaza-
chlorin and unsubstituted SubPz.[4] Unfortunately, chemical
manipulation of unsubstituted SubPz is not feasible due to
its proven instability once formed.[4] Finally, the use of
boron trichloride is incompatible with many functions, in
particular, with precursors bearing boron-coordinating het-
eroatoms such as nitrogen or even oxygen. These synthetic
limitations have precluded the development of a variety of
SubPz derivatives, parallel to those reported for the SubPc[2]
and subporphyrin (SubP)[5,6] series.
with SubPcs. For example, SubPzs exist only as boronACTHUNTGRNEUNG(III)
complexes. In addition, they show great potential as func-
tional chromophores owing to their strong fluorescence and
their cone-shaped, aromatic structure arising from a 14p-
electron circuit. As a distinctive feature, SubPzs strongly
absorb in the green-yellow regions.[3]
Unlike the extensively studied chemistry of SubPcs, that
of SubPzs remains mostly unexplored, mainly due to the
limited synthetic methodology for the construction of the
SubPzs represent far more than just SubPc derivatives
lacking the fused benzene rings, but they are rather a dis-
tinctive class of porphyrinoids. This is true because in these
series, the peripheral substituents are directly attached to
the macrocyclic core. Hence, these functions exert much
stronger influence on the aromatic heteroannulene, related
to their SubPc congeners, whose peripheral substituents are
appended to the fused benzene rings. A typical example is
hexaethylsulfanyl-substituted SubPz 1, which exhibits a very
strong and broad charge-transfer band at 438 nm (the stron-
gest absorption of the spectrum) and a bathochromically
shifted (60 nm) and broad Q-band at about 560 nm. These
striking electronic alterations upon peripheral thioalkyl sub-
stitution arise from p-donation from the sulfur lone pair to
the SubPz core. The spectral changes are about twofold
larger than that produced in SubPcs. Despite this potential,
there have been only limited examples of peripherally sub-
[a] T. Higashino, Dr. M. S. Rodrꢀguez-Morgade, Prof. T. Torres
Departamento de Quꢀmica Orgꢁnica
Universidad Autꢂnoma de Madrid
Cantoblanco, 28049 Madrid (Spain)
Fax : (+34)914973966
E-mail: salome.rodriguez@uam.es
tomas.torres@uam.es
[b] T. Higashino, Prof. Dr. A. Osuka
Department of Chemistry
Graduate School of Science, Kyoto University, Sakyo-ku
Kyoto 606-8502 (Japan)
Fax : (+81)75-753-3970
E-mail: osuka@kuchem.kyoto-u.ac.jp
[c] Prof. T. Torres
IMDEA-Nanociencia, c/Faraday, 9, Campus de Cantoblanco
28049 Madrid (Spain)
Supporting Information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201301140.
Chem. Eur. J. 2013, 19, 10353 – 10359
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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stituted SubPzs.[1a,c,3,7] Bearing this in mind, we envisaged
peripheral functionalization of SubPzs as a powerful tool to
obtain dyes exhibiting exceptional optical and redox proper-
ties. Herein, we report the effective peripheral arylation of
SubPzs by Pd-catalyzed cross-coupling reaction of hexae-
thylsulfanylated SubPz 1 with arylboronic acids. As expect-
ed, the newly synthesized hexaaryl-substituted SubPzs show
electronic properties far beyond what is usually accessible
within the SubPc and SubP families. The use of such a con-
vergent synthetic protocol is unprecedented within porphyr-
in chemistry and represents the first peripheral modification
of preformed SubPzs.[8]
was improved up to 23% by performing the reaction at
room temperature, although a longer reaction time was re-
quired (5 days).
1
Hexaarylated SubPzs 2a–g were characterized by MS, H,
13C, and 11B NMR spectroscopies (see the Supporting Infor-
mation), as well as UV/Vis and fluorescence spectroscopies.
The redox properties of 2a–g were also studied by cyclic
voltammetry (CV) and differential pulse voltammetry
(DPV). In addition, relevant information about the molecu-
lar structure of hexaarylated-SubPzs was obtained from X-
ray diffraction analysis of suitable single crystals obtained
for 2b.
1
The H NMR spectrum of hexaphenyl-SubPz 2a exhibits
the aromatic protons corresponding to the axial tert-butyl-
phenoxy substituent quite shielded (Figure S3a, the Sup-
porting Information), owing to the diatropic ring-current of
the 14p-electron SubPz core. Importantly, the peripheral
phenyl rings appear as a single set of two signals, suggesting
free rotation of the phenyl rings. Taking into account the
SubPz cone-shape, restricted rotation of the peripheral sub-
stituents would split each signal in two.[11,12] The same con-
Results and Discussion
Synthesis: We have applied the methodology developed by
Liebeskind and Srogl consisting in the palladium-catalyzed,
copper(I) thiophene-2-carboxylate (CuTC)-mediated cou-
pling of boronic acids with heteroaromatic thioethers.[9] The
SubPz precursor was provided with a tert-butylphenoxy
group at the axial position to guarantee solubility of inter-
mediates and products in organic solvents. The SubPz 1
(Scheme 1) was easily synthesized in 14% yield by using re-
ported procedures,[1,10] and used in all the cross-coupling re-
actions as the heteroaromatic reactant.
1
clusion can be inferred from the H NMR spectra of all the
other hexaaryl-SubPzs 2b–g (Figure S4a–S9a in the Sup-
porting Information).
Optical properties: Contrasting with what was observed for
the hexaarylated SubPc series,[13] the peripheral aryl groups
of hexaaryl-SubPzs 2a–g strongly interact with the macrocy-
clic core. This becomes very apparent when analyzing the
optical spectra of these compounds (Figure 1 and Table 1).
Table 1. Optical properties of SubPzs in CHCl3.
SubPz
Absorption l [nm]
(e [104 mÀ1 cmÀ1])
Fluorescence
lem [nm][a]
Pr6SubPz[1c]
1
291 (3.8), 329 (sh), 499 (4.0)
282 (2.4), 438 (2.7), 556 (2.4)
250 (4.4), 304 (4.0), 395 (3.2), 539 (5.2)
271 (5.9), 434 (3.9), 553 (4.4)
287 (8.7), 454 (4.5), 560 (5.0)
296 (9.3), 503 (5.3), 570 (4.2)
297 (6.1), 386 (3.4), 547 (5.7)
252 (4.7), 308 (4.3), 384 (3.0), 538 (5.7)
276 (6.8), 312 (5.0), 394 (3.4), 545 (5.8)
520
682
563
612
654
765
581
564
574
2a
2b
2c
2d
2e
2 f
2g
[a] Excited at the Q-band.
Thus, hexaarylation of SubPc produces a redshift in the
Q-band of the macrocycle of only 5–10 nm with respect to
the hexaalkylated derivative.[13,14] However, hexaphenyl-
SubPz 2a shows the corresponding Q-band at 539 nm (Fig-
ure 1b), that is, bathochromically shifted 40 nm with respect
to the hexaalkylated SubPz (Table 1).[1a] However, the most
remarkable feature in the absorption spectrum of 2a is the
presence of an intense charge-transfer absorption at 395 nm,
which is diagnostic of electronic communication between
the phenyl rings and the SubPz macrocycle. Such a CT band
does not appear in the electronic spectrum of hexaaryl-
SubPcs.[13]
Scheme 1. The synthesis of hexaaryl-SubPzs.
The CuTC-mediated cross-coupling reaction of 1 with a
variety of arylboronic acids at 608C afforded the hexaarylat-
ed-SubPzs 2a–g in 20–43% yields (Scheme 1). In most
cases, the six-fold coupling proceeded smoothly for 20 h,
using three equivalents of arylboronic acid and CuTC, and
10% mol of palladium catalyst per thioether unit. An excep-
tion was found with 2d, which was obtained in only 3%
yield by using our standard protocol. In this case, the yield
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Arylation of Subporphyrazines
FULL PAPER
hypsochromically only by 1–11 nm, related to 2a. On the
other hand, whereas the p-electron-accepting nitro- and car-
boxy groups produce a slight redshift of 6–8 nm in the Q-
bands, SubPz 2 f, substituted with the s-electron-accepting
CF3 group, exhibits this band at the same energy as 2a.
Visible-light excitation in the 510–570 nm range (Q-bands
of 1 and 2a–g) generates different fluorescence patterns de-
pending on the SubPz peripheral substitution. Except for 2b
and 2c, hexaaryl-SubPzs display fluorescence spectra that
look like virtual mirror images to the absorption (Figure 1,
dotted lines).
For SubPzs 2b and 2c bearing para-methoxy and para-
methylsulfanyl groups, respectively, at the peripheral phenyl
rings, the emission bands broaden. The Stokes shifts in hex-
aalkyl-[1c] and hexaphenyl-SubPzs are in the similar range
(21–26 nm). Electron-donating groups increase this value in
the order NMe2 (195 nm)>MeS (94 nm)>MeO (59 nm).
The differences in the quantum yields are also notable.
Thus, whereas 2a,d,e,f, and g show low quantum yields
(0.001–0.008) in the same range as the SubPz 1, functionali-
zation with methoxy and methylsulfanyl-substituents in 2b
and 2c induces much stronger emissions (0.026–0.033).
X-ray crystallography: The optical properties of hexaaryl-
SubPzs can be rationalized taking into account their molecu-
lar structure. Single crystals of 2b suitable for X-ray diffrac-
tion analysis were obtained by vapor diffusion of octane
into a solution of this SubPz in 1,2-dichloroethane. The crys-
tal structure[16] (Figure 2a and 2b) revealed the curved
SubPz shape with a bowl depth of 1.742 ꢄ, very similar to
that of Pr6SubPz.[10,12]
Figure 1. UV/Vis absorption (c) and emission (a) spectra of (a) 1,
(b) 2a, (c) 2b, (d) 2c, (e) 2d, (f) 2e, (g) 2 f, and (h) 2g in CHCl3.
Notably, the redshift of the SubPz Q-band is quantitative-
ly comparable to that produced upon peripheral arylation of
porphyrazines (Pz).[15] The charge-transfer band, however, is
exceedingly more intense in the SubPz class than in the Pz
series.[15]
Importantly, the electronic properties of hexaaryl-SubPzs
can be fine-tuned by introducing groups of distinct nature at
the para positions of the peripheral aryl groups (see
Figure 1 and Table 1). Here, the effects are different de-
pending on the electron donor or acceptor abilities of the
para substituents. SubPzs 2b–d bearing p-electron-donating
substituents display Q-bands considerably redshifted with
respect to the hexaphenyl-SubPz 2a. The largest effect is ob-
served for the dimethylamino-substituted hexaaryl-SubPz
2d, which shows this absorption at 570 nm. p-Electron-do-
nating substituents also produce an increase in the molar ab-
sorptivity of the CT bands and shift these absorptions to the
lower-energy side. The extent of both effects follow the
order Me2N>MeS>MeO.
Electron-withdrawing groups produce more modest alter-
ations in the CT and Q-bands of the hexaarylated SubPzs. In
compounds 2e–g CT absorptions are less intense and shifted
Figure 2. X-ray crystal structure of 2b (a) top view, (b) side view, and
(c) SubPz dimer with the encapsulated solvent, with the thermal ellip-
soids drawn at the 50% probability level.
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M. S. Rodrꢀguez-Morgade, A. Osuka, T. Torres, and T. Higashino
A significant feature of the structure of 2b is the relative-
ly small dihedral angles of aryl groups with respect to the
plane defined by the pyrrole to which they are attached.
These small angles, which range from 31.29 to 50.778, are fa-
vorable for p-conjugation over the entire molecule. Remark-
ably, the dihedral angles of b-phenyl substituents in subpor-
phyrins are much larger, in the 65–828 range. In the latter
case, the presence of three additional aryl groups at the
SubP meso-positions give rise to more congested molecules,
with restricted rotation of their peripheral aryl groups.[17]
To accommodate the six aryl groups in the meager SubPz
peripheral space, each benzene ring in a pyrrole unit is
tilted by 11–188 with respect to the contiguous benzene
ring. The corresponding dihedral angle between two adja-
cent benzene rings within octaarylporphyrazines is consider-
ably larger (about 558).[15b] Overall, the largest dihedral
angle between two consecutive benzene rings is of 45.238
for SubPzs and 89.188 for Pzs. The observed free rotation
and small dihedral angles of the peripheral aryl substituents
À À
in the SubPz class are related to their smaller Ca N Ca
angles with respect to that of Pzs (114 vs. 1248), which pro-
vide more room for peripheral substituents. Octaphenyl-Pzs
are more congested than hexaphenyl-SubPzs and so, the
aryl groups are forced to take less coplanar conformations
in Pzs, with the consequent mitigation of conjugative effects.
This gives rise to stronger influences of the peripheral aryl
substituents on the electronic properties of the subporphyra-
zines related to those of porphyrazines.
Two molecules of 2b arrange a dimer in the solid state,
with the two concave surfaces facing each other and forming
a cavity that houses a molecule of 1,2-dichloroethane (Fig-
Figure 3. Cyclic voltammograms of (a) 1, (b) 2a, (c) 2b, (d) 2c, (e) 2d,
(f) 2e, (g) 2 f, and (h) 2g. Solvent: CH2Cl2; scan rate: 0.05 VsÀ1; working
electrode: glassy carbon; reference electrode: Ag/AgClO4; electrolyte:
Bu4NPF6.
À
ure 2c). The B B distance between the SubPz pair is
9.69 ꢄ. One molecule is rotated by 30.348 with respect to
the other SubPz, so that the aryl groups are placed in alter-
À
nated configuration. The O O distance between two contig-
uous methoxy groups, that is, one from a SubPz unit and the
other one from the other SubPz unit, ranges from 3.87–
5.31 ꢄ.
The effect of para substituents on the redox properties of
hexaaryl-SubPzs is remarkable and varies according to the
electronic characteristics of the groups. Therefore, six nitro
moieties shift the first electrochemical reduction by 460 mV
towards more positive potentials (from À1.31 for 2a to
À0.85 V for 2e), whereas the amino functions of 2d shift the
same process cathodically by 250 mV (Table 2). This is con-
sistent with significant perturbation of the electron density
Electrochemistry: The electrochemical properties of hexaar-
yl-SubPzs 2a–g were studied by CV (Figure 3) and DPV
(Figure S10 in the Supporting Information). Table 1 and
Table S1 (the Supporting Information) give the redox poten-
tials derived from these measurements.
SubPzs 1 and 2a–g exhibit a larger number of redox proc-
esses than those exhibited by hexaalkyl-SubPzs.[12] In partic-
ular, whereas the latter show only one reduction and one
oxidation peak, all the SubPzs reported in this work display
at least three reduction processes that are reversible in most
cases, and one or more oxidation peaks that are irreversible
for compounds bearing thioether functions (1 and 2c). An-
other interesting feature when comparing hexaalkyl- and
hexaphenyl-SubPzs is that 2a is easier to reduce and more
difficult to oxidize. Again, this differs from what has been
observed upon peripheral perarylation of Pzs: Octaphenyl-
Pzs are more resistant to both electrochemical oxidation
and reduction than octaalkyl-Pzs.[18]
Table 2. Electrochemical oxidation and reduction potentials, E1/2 and Ep
versus Fc/Fc+ (in V) for the SubPzs studied in this work.
ox3
ox2
ox1
red1
red2
red3
Ep
Ep
Ep
E1/2
E1/2
E1/2
1
–
–
+1.25[a]
–
+0.96[a]
+0.97[b]
+0.80[b]
+0.90[a]
+0.22[b,d]
+1.16[b]
+1.10[b]
+1.11[b]
À1.29
À1.31
À1.40
À1.30
À1.56
À0.85
À1.05
À1.08
À1.67
À1.75
À1.82
À1.71
À1.99[a]
À1.21
À1.57
À1.53
À2.04
À2.02
À2.11
À1.99
À2.28[c]
À1.33
À1.89
À1.80
2a
2b
2c
2d
2e
2 f
2g
+1.46[c]
+1.20[a]
+1.09[a]
+0.38[b]
–
–
+0.90[a]
–
–
–
+1.40[c]
+1.38[c]
[a] Irreversible process (potential corresponds to the peak potential).
[b] Taken from the DPV. [c] In the window limit. [d] Multielectronic
process.
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Arylation of Subporphyrazines
FULL PAPER
of the SubPz macrocycle by the para substituents of periph-
eral aryl groups.
Conclusion
The trend in the first reduction potentials correlates with
the Hammett constants (sp) corresponding to the substitu-
ents, so that the potentials are shifted cathodically in the
A series of perarylated subporphyrazines has been prepared
through a convergent strategy employing a palladium-cata-
lyzed, CuTC-mediated coupling of hexaethylsulfanylated
SubPz with arylboronic acids. The ready availability of the
bis(thioether)maleonitrile precursors on a multigram scale
compensates the low yield for the cyclotrimerization reac-
tion to afford 1 as a precursor. Hexaaryl-SubPzs consist in
extended-conjugated systems that display small dihedral
angles between the benzene and the pyrrole rings. The intro-
duced aryl substituents exert notable perturbations on the
optical and electronic properties of the SubPz core, making
these modifications a promising tool to tune SubPzs. The
synthetic method provides a useful platform for further sym-
metric or unsymmetric functionalization of SubPzs, which is
actively being pursued in our laboratories.
order:
NO2 <CF3 <CO2Me<HꢀMeS<MeO<NMe2
(Figure 4).[19]
Experimental Section
Instrumentation and materials: Commercially available solvents and re-
agents were used without further purification unless otherwise men-
tioned. Silica-gel column chromatography was performed on Wakogel C-
200 or C-300. UV/Vis absorption spectra were recorded with a Shimadzu
UV-3100PC spectrometer. Fluorescence spectra were recorded on a Shi-
madzu RF-5300PC spectrometer. Absolute fluorescence quantum yields
were determined on HAMAMATSU C9920–02S. 1H, 13C, 11B, and
19F NMR spectra were recorded with a JEOL ECA-600 spectrometer
(operating at 600 MHz for 1H, 150 MHz for 13C, 192 MHz for 11B, and
565 MHz for 19F) by using the residual solvent as the internal reference
for 1H (CDCl3: d=7.26 ppm), the residual solvent as the internal refer-
ence for 13C (CDCl3: d=77.16 ppm), BF3·Et2O as the external reference
for 11B (d=0.00 ppm), and hexafluorobenzene as the external reference
for 19F (d=À162.9 ppm). Mass spectra were recorded with a BRUKER
microTOF LC by using the ESI-TOF method in the positive ion mode in
an acetonitrile solution. Single-crystal X-ray diffraction analysis data for
compound 2b was collected at À1808C with a Rigaku R-AXIS RAPID
II diffraction by using graphite monochromated CuKa radiation (l=
1.54187 ꢄ). The structures were solved by using the direct method
(SHELXS-97). Redox potentials were measured by the cyclic voltamme-
try method on an ALS electrochemical analyzer model 660.
Figure 4. Hammett plot of first reduction potentials of SubPzs 2a–g.
The oxidation potentials of the macrocycles show less var-
iation across the series (Table 2). The first oxidation process
for compounds 2a,b,e,f, and g is partially chemically reversi-
ble[20] (see Figure 3 and S10, the Supporting Information)
and is followed by irreversible oxidations afterwards. In
agreement with what was expected, the trend correlates
quite well with the corresponding Hammett constants for
each substituent. Thus, compounds 2e–g have more positive
oxidation potentials than 2a, whereas 2b shows a less-posi-
tive potential because of their electron-withdrawing or -do-
nating substituents, respectively.
Synthesis: The synthetic procedure for CuTC can be found in the Sup-
The CV and DPV of 2d (see Figure S10, the Supporting
Information) reveal two additional oxidation processes prior
to the oxidation of the SubPz ring. The first oxidation wave
consists in several processes involving three electrons,
whereas the second wave is a reversible oxidation also in-
volving three electrons. An examination of the redox behav-
ior of aromatic amines suggests that both processes are at-
tributable to the six amino groups.[21] Separate oxidation
processes imply that the para-amino substituents communi-
cate with each other in an electrochemical sense through the
SubPz core. As a result of the oxidation processes on the
amino groups, compound 2d has a more positive oxidation
porting Information.
4-tert-Butylphenoxy[2,3,7,8,12,13-hexa(ethylthio)subporphyrazinato]-
A
ACHTUNGTRENNUNG
a
2.0 mmol) and the mixture was heated at 1008C for 45 min. The solvent
was removed under reduced pressure. Then, the residue was dissolved in
toluene (4 mL) and 4-tert-butylphenol (1.50 g, 10 mmol) was added. The
resulting solution was stirred at reflux for 2 h and afterwards the solvent
was evaporated. Column chromatography on silica gel using a 20:1 mix-
ture of n-hexane and ethyl acetate gave 1 (70 mg, 14%) as a red syrup.
1H NMR (600 MHz, CDCl3): d=6.82 (d, J=8.6 Hz, 2H; H3’,5’), 5.31 (d,
J=8.6 Hz, 2H; H2’,6’), 4.03 (m, 6H; -SCH2CH3), 3.66 (m, 6H;
-SCH2CH3), 1.60 (t, J=7.2 Hz, 18H; -SCH2CH3) and 1.14 ppm (s, 9H;
tBu); 13C NMR (150 MHz, CDCl3): d=154.1, 150.1, 144.5, 151.6, 125.7,
119.2, 34.0, 31.5, 29.4, 15.8 ppm; 11B NMR (192 MHz, CDCl3): d=
À16.32 ppm. UV/Vis (CHCl3): l (e)=282 (24000), 438 (27000), 556 nm
(24000 mÀ1 cmÀ1); fluorescence (CHCl3) lex =530 nm; lmax =682 nm; FF =
0.001; HRMS (ESI-TOF, +): m/z calcd for C34H44BN6OS6: 755.1995
[M+H]+; found: 755.1987.
ACHTUNGTRENNUNG
for the [SubPz1À]/[SubPz2À] couple than 2b (+0.90 and
+0.80 V, respectively).
Typical procedure for the cross-coupling of subporphyrazine with boronic
acids: An oven-dried flask cotaining hexa(ethylthio)subporphyrazine 1
Chem. Eur. J. 2013, 19, 10353 – 10359
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10357

M. S. Rodrꢀguez-Morgade, A. Osuka, T. Torres, and T. Higashino
(15.1 mg, 20 mmol; 1 equiv), boronic acid (18 equiv), [Pd
(PPh3)4]
8.36 (d, J=8.7 Hz, 12H; H3’’,5’’), 7.99 (d, J=8.7 Hz, 12H; H2’’,6’’), 6.90 (d,
J=8.6 Hz, 2H; H3’,5’), 5.32 (d, J=8.6 Hz, 2H; H2’,6’), 1.11 ppm (s, 9H;
tBu); 13C NMR (150 MHz, CDCl3): d=156.4, 149.8, 148.5, 144.6, 136.7,
133.6, 132.1, 126.3, 124.5, 117.1, 34.1, 31.5 ppm. 11B NMR (192 MHz,
(13.9 mg, 12 mmol; 60 mol%), and CuTC (68.6 mg, 360 mmol; 18 equiv)
was purged with N2, then charged with dry THF (2 mL). The mixture
was stirred at 608C for 20 h under N2 atmosphere. The reaction mixture
was cooled to room temperature and passed through a short silica gel
column using THF as eluent. After the solvent was removed, the residue
was purified by silica gel column chromatography. The products were re-
crystallized from CH2Cl2 and n-hexane. Unless otherwise noted, all reac-
tions were performed according to this typical procedure.
CDCl3): d=À16.18 ppm; UV/Vis (CHCl3):
l (e)=297 (61000), 386
(34000), 547 nm (57000 mÀ1 cmÀ1); fluorescence (CHCl3): lex =510 nm;
lmax =581 nm, FF =0.001; HRMS (ESI-TOF, +): m/z calcd for
C58H38BN12O13: 1121.2778 [M+H]+; found: 1121.2750.
4-tert-Butylphenoxy[2,3,7,8,12,13-hexa(4-trifluoromethylphenyl) subpor-
ACHUTNGRENUpNG hyrazinato]boronAHCTUNGTRENN(UNG III) (2 f): The residue was purified by column chroma-
4-tert-Butylphenoxy[2,3,7,8,12,13-hexaphenylsubporphyrazinato]boron-
tography on silica gel (10:40:1 mixture of CH2Cl2/n-hexane/Et2O) to give
the target compound as a red solid (7.0 mg, 28%). 1H NMR (600 MHz,
CDCl3): d=7.95 (d, J=8.3 Hz, 12H; H3’’,5’’), 7.74 (d, J=8.3 Hz, 12H;
H2’’,6’’), 6.88 (d, J=8.6 Hz, 2H; H3’,5’), 5.33 (d, J=8.6 Hz, 2H; H2’,6’),
1.12 ppm (s, 9H; tBu); 13C NMR (150 MHz, CDCl3): d=156.6, 150.2,
144.1, 134.5, 133.6, 131.6, 131.2, 126.1, 126.0, 125.9, 117.1, 34.1, 31.8 ppm;
11B NMR (192 MHz, CDCl3): d=À16.14 ppm. 19F NMR (565 MHz,
ACHTUNGTRENNUNG(III) (2a): The residue was purified by column chromatography on silica
gel (1:20 mixture of ethyl acetate/n-hexane) to give the target compound
as a red solid (6.0 mg, 35%). 1H NMR (600 MHz, CDCl3): d=7.89 (m,
12H; Ph), 7.41 (m, 18H; Ph), 6.85 (d, J=8.6 Hz, 2H; H3’,5’), 5.34 (d, J=
8.6 Hz, 2H; H2’,6’), 1.11 ppm (s, 9H; tBu); 13C NMR (150 MHz, CDCl3):
d=157.0, 150.8, 143.1, 133.7, 131.9, 131.5, 128.5, 128.3, 126.0, 117.1, 34.0,
31.5 ppm; 11B NMR (192 MHz, CDCl3): d=À15.98 ppm; UV/Vis
CDCl3): d=À62.62 ppm; UV/Vis (CHCl3):
l (e)=252 (47000), 308
(CHCl3):
l (e)=250 (44000), 304 (40000), 395 (32000), 539 nm
(43000), 384 (30000) and 538 nm (57000 mÀ1 cmÀ1); fluorescence (CHCl3):
lex =500 nm; lmax =564 nm; FF =0.001; HRMS (ESI-TOF, +): m/z calcd
for C64H38BF18N6O: 1259.2918 [M+H]+; found: 1259.2908.
(52000 mÀ1 cmÀ1); fluorescence (CHCl3): lex =500 nm; lmax =563 nm; FF =
0.008; HRMS (ESI-TOF, +): m/z calcd for C58H44BN6O: 851.3674
[M+H]+; found: 851.3651.
4-tert-Butylphenoxy[2,3,7,8,12,13-hexa(4-methoxycarbonylphenyl)
4-tert-Butylphenoxy[2,3,7,8,12,13-hexa(4-methoxyphenyl)subporphyrazi-
subporphyrazinato]boronACHTNUTRGNE(NUG III) (2g): The residue was purified by column
nato] boronACHTUNGTRENNUNG(III) (2b): The residue was purified by column chromatogra-
chromatography on silica gel (20:1 mixture of CH2Cl2/Et2O) to give the
target compound as a red solid (10.3 mg, 43%). 1H NMR (600 MHz,
CDCl3): d=8.11 (d, J=8.3 Hz, 12H; H3’’,5’’), 7.90 (d, J=8.3 Hz, 12H;
H2’’,6’’), 6.87 (d, J=8.6 Hz, 2H; H3’,5’), 5.34 (d, J=8.6 Hz, 2H; H2’,6’), 3.98
(s, 18H; -COOMe), 1.12 ppm (s, 9H; tBu); 13C NMR (150 MHz, CDCl3):
d=166.8, 156.6, 150.3, 143.8, 135.7, 133.9, 131.3, 130.6, 130.1, 129.1, 117.1,
52.5, 34.0, 31.5 ppm; 11B NMR (192 MHz, CDCl3): d=À16.10 ppm; UV/
phy on silica gel (10:10:1 mixture of CH2Cl2/n-hexane/Et2O) to give the
target compound as violet crystals (7.6 mg, 37%). Single crystals suitable
for X-ray diffraction analysis were obtained by vapor diffusion of octane
1
into its 1,2-dichloroethane solution. H NMR (600 MHz, CDCl3): d=7.79
(d, J=8.2 Hz, 12H; H2’’,6’’), 6.92 (d, J=8.2 Hz, 12H; H3’’,5’’), 6.81 (d, J=
8.6 Hz, 2H; H3’,5’), 5.30 (d, J=8.6 Hz, 2H; H2’,6’), 3.88 (s, 18H; -OMe)
and 1.09 ppm (s, 9H; tBu); 13C NMR (150 MHz, CDCl3): d=159.9, 156.8,
151.0, 142.8, 132.7, 132.3, 125.9, 124.6, 117.0, 114.2, 55.4, 33.9, 31.5 ppm;
11B NMR (192 MHz, CDCl3): d=À16.05 ppm; UV/Vis (CHCl3): l (e)=
271 (59000), 434 (39000), 553 nm (44000 mÀ1 cmÀ1); fluorescence (CHCl3):
lex =515 nm; lmax =612 nm, FF =0.026; HRMS (ESI-TOF, +): m/z calcd
for C64H56BN6O7: 1031.4308 [M+H]+; found: 1031.4290.
Vis (CHCl3):
l (e)=276 (68000), 312 (50000), 394 (34000), 545 nm
(58000 mÀ1 cmÀ1); fluorescence (CHCl3): lex =500 nm; lmax =574 nm; FF =
0.003; HRMS (ESI-TOF, +) calcd for C70H56BN6O13: m/z calcd for
1199.4004 [M+H]+; found: 1199.3977.
4-tert-Butylphenoxy[2,3,7,8,12,13-hexa(4-methylthiophenyl)subporphyrazi-
nato] boronACHTUNGTRENNUNG(III) (2c): The residue was purified by column chromatogra-
phy on silica gel (10:30:1 mixture of CH2Cl2/n-hexane/Et2O) to give the
target compound as a purple solid (7.7 mg, 34%). 1H NMR (600 MHz,
CDCl3): d=7.80 (d, J=7.8 Hz, 12H; H2’’,6’’), 7.28 (d, J=7.8 Hz, 12H;
H3’’,5’’), 6.83 (d, J=8.6 Hz, 2H; H3’,5’), 5.31 (d, J=8.6 Hz, 2H; H2’,6’), 2.56
(s, 18H; -SMe) and 1.10 ppm (s, 9H; tBu);13C NMR (150 MHz, CDCl3):
d=156.6, 150.8, 143.0, 139.8, 132.7, 131.6, 128.3, 126.0, 125.9, 116.9, 33.9,
31.5, 15.4 ppm; 11B NMR (192 MHz, CDCl3): d=À16.14 ppm; UV/Vis
(CHCl3): l (e)=287 (87000), 454 (45000), 560 nm (50000 mÀ1 cmÀ1); fluo-
rescence (CHCl3) lex =520 nm; lmax =654 nm; FF =0.033; HRMS (ESI-
TOF, +): m/z calcd for C64H56BN6OS6 [M+H]+ 1127.2938; found:
1127.2935.
Acknowledgements
Support is acknowledged from the Spanish MICINN (CTQ2011–24187/
BQU and the CONSOLIDER INGENIO 2010, CSD2007–00010 on Mo-
lecular Nanoscience) and the CAM (MADRISOLAR-2, S2009/PPQ/
1533). This work was also supported by Grants-in-Aid (No. 22245006 (A)
and 20108001 “pi-Space”) for Scientific Research from MEXT. T.H. ac-
knowledges a JSPS Fellowship for Young Scientists.
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(600 MHz, CDCl3): d=7.92 (d, J=8.8 Hz, 12H; H2’’,6’’), 6.80 (d, J=
8.6 Hz, 2H; H3’,5’), 6.78 (d, J=8.8 Hz, 12H; H3’’,5’’), 5.36 (d, J=8.6 Hz,
2H; H2’,6’), 3.04 (s, 36H; -NMe2), 1.09 ppm (s, 9H; tBu); 13C NMR
(150 MHz, CDCl3): d=157.0, 151.6, 150.1, 142.1, 132.3, 131.4, 125.7,
121.2, 117.0, 112.3, 40.6, 33.9, 31.5 ppm; 11B NMR (192 MHz, CDCl3): d=
À15.69 ppm; UV/Vis (CHCl3): l (e)=296 (93000), 503 (53000), 570 nm
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ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 10353 – 10359

Arylation of Subporphyrazines
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Received: March 25, 2013
Published online: June 19, 2013
Chem. Eur. J. 2013, 19, 10353 – 10359
ꢃ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
10359