High-Boron-Content Porphyrin-Cored Aryl Ether Dendrimers: Controlled Synthesis, Characterization, and Photophysical Properties

Article abstract of DOI:10.1021/acs.inorgchem.5b00618

The synthesis and characterization of a set of poly(aryl ether) dendrimers with tetraphenylporphyrin as the core and 4, 8, 16, or 32 closo-carborane clusters are described. A regioselective hydrosilylation reaction on the allyl-terminated functions with c

Full text of DOI:10.1021/acs.inorgchem.5b00618

Article
pubs.acs.org/IC
High-Boron-Content Porphyrin-Cored Aryl Ether Dendrimers:
Controlled Synthesis, Characterization, and Photophysical Properties
†
,‡
§,‡
†
†
Justo Cabrera-Gonzal
́
ez, Elba Xochitiotzi-Flores, Clara Vin
̃
as, Francesc Teixidor,
§
§
⊥
∥
ez*,†
Hec
́
tor García-Ortega, Norberto Farfan
́
, Rosa Santillan, Teodor Parella, and Rosario Nun
́
̃
†
Institut de Cien
̀
cia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain
Facultad de Química, Departamento de Química Organica, Universidad Nacional Autonoma de Mexico (UNAM), 04510 Mex
ico
Departamento de Química, Centro de Investigacion
ico
Servei de Ressonan
S Supporting Information
§
́
́
́
́
ico
D.F., Mex
́
⊥
́
y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 Mex
́
ico D.F.,
Mex
́
∥
̀
̀ ̀
cia Magnetica Nuclear, Universitat Autonoma de Barcelona (UAB), E-08193 Bellaterra, Barcelona, Spain
*
ABSTRACT: The synthesis and characterization of a set of
poly(aryl ether) dendrimers with tetraphenylporphyrin as the
core and 4, 8, 16, or 32 closo-carborane clusters are described.
A regioselective hydrosilylation reaction on the allyl-termi-
nated functions with carboranylsilanes in the presence of
Karstedt’s catalyst leads to different generations of boron-
enriched dendrimers. This versatile approach allows the
incorporation of a large number of boron atoms in the
dendrimers’ periphery. Translational diffusion coefficients (D)
determined by DOSY NMR experiments permit estimation of the hydrodynamic radius (R ) and molecular size for each
H
dendrimer. Furthermore, a notable correlation between D and the molecular weight (MW) is found and can be used to predict
their overall size and folding properties. The UV−vis and emission behavior are not largely affected by the functionalization,
therefore implying that the presence of carboranes does not alter their photoluminescence properties.
INTRODUCTION
phobic character of carboranes can enhance the interactions
■
20−24
between pharmaceuticals and their receptors,
and they
Dendrimers are treelike branched polymers with low
polydispersity and a high degree of versatility that tend to
adopt globular structures with a well-defined three-dimensional
have been extensively involved in areas of drug discovery, such
25−28
as pharmacophores and biologically active compounds.
During the last decades, several boron-containing porphyrins,
1
2
shape. Since the first synthesis reported by Tomalia et al.,
29,30
31
with closo-carborane
and nido-carborane, have been
these materials have attracted the attention of many research
groups because they can be built in a controlled manner,
allowing versatility in the nucleus, branching units, or dendrons
as well as in the terminal groups. This allows one to change
the properties of dendrimers and also to modulate their
behavior, with the goal centered on the design and synthesis of
synthesized and evaluated in vitro and in vivo as promising
32−35
BNCT agents.
The combined action of a porphyrin used
3
as a core with dendrons of poly(aryl ether) for the synthesis of
36
dendrimers was first reported by Inoue and collaborators. By
using Frechet’s methodology, they prepared an iron porphyrin
covalently encapsulated within a large aryl ether dendrimer cage
́
4
dendrimers more specific for certain areas, such as carriers for
37
5
,6
as the first monomolecular model of hemoproteins.
On the basis of both the biocompatibility of porphyrin-cored
drug delivery. For all of these reasons, they emerged as a new
7
appealing class of particles for nanomedicine. In this respect,
boron-enriched dendrimers have been developed for different
3
8−42
poly(aryl ether) dendrimers
and the bioactivity of
21
carborane-containing molecules, in this work our goal is the
synthesis and characterization of dendrimers that contain a
large number of carborane clusters, in order to obtain
biocompatible boron-rich molecules. Synthetic aspects as well
as a complete characterization of free-base and zinc-metalated
porphyrin-cored dendrimers before and after the incorporation
of closo-carboranes are discussed. The molecular sizes for these
groups as boron carriers for boron neutron capture therapy
8
−10
(
BNCT).
Our group has also contributed to the search of
synthetic strategies for the preparation of high-boron-content
neutral dendrimeric systems that incorporate closo-carbor-
1
1,12
anes
nido-carborane
cobaltabis(dicarbollide) fragments.
and water-soluble polyanionic dendrimers bearing
1
3−15
as well as metallodendrimers containing
1
6−18
As is well-known,
icosahedral carborane derivatives have recently attracted
much attention in biomedical and medicinal applications
because of their extraordinary characteristics. The hydro-
Received: March 20, 2015
19
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.5b00618
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Article
Scheme 1. Route of the Preparation of Dendrimers 1c−1e and 2c−2e
Scheme 2. Metalation of the Porphyrin Core of Dendrimers 1d−1e and 2d−2e with Zinc(II)
4
5,46
kinds of dendrimers were estimated before and after the
incorporation of carborane clusters from their hydrodynamic
Information, SI).
After demethylation with HBr and
47
48
49
CH COOH, porphyrin cores 1b and 2b were obtained
3
radii (R ), which were determined using translational diffusion
́
(see the SI). On the other hand, Frechet dendron types, Br-
H
coefficients (D) from DOSY NMR experiments. A comparative
study of the absorption and emission properties for all
compounds has been carried out, and the influence of the
cluster attached to the dendrimer periphery on these
photophysical properties has been investigated. We currently
focus our research on the study of the biocompatibility and
cytotoxicity of these dendrimers for potential biomedical
applications.
dendron-1 and Br-dendron-2, with allyl groups at the
periphery were prepared by esterification of 3,5-dihydrox-
ybenzoic acid in methanol and H SO , followed by coupling
2
4
with allyl bromide in the presence of K CO , KI, and acetone.
2
3
The subsequent reduction of the ester with LiAlH4 in
tetrahydrofuran gave benzylic alcohol, which was treated with
50−53
SOCl and pyridine to generate Br-dendron-1.
From the
2
reaction of 3,5-dihydroxybenzylic alcohol and Br-dendron-1, a
second derivative of benzylic alcohol was obtained and
submitted to a second halogenation to give Br-dendron-
RESULTS AND DISCUSSION
■
5
4,55
2
.
The spectroscopic data for dendrons and intermediates
Synthesis of Carboranyl-Containing Porphyrin-Cored
Dendrimers. Different generations of poly(aryl ether)
dendrimers with terminal allyl ether groups and a porphyrin
as the core have been used as a platform to prepare high-boron-
content macromolecules after functionalization with carboranyl
are in agreement with those reported in the literature. The
reaction of porphyrins lb or 2b with allyl bromide, Br-dendron-
1, or Br-dendron-2 in acetone in the presence of K CO and
2 3
56
KI leads to the formation of dendrimers with 4 (1c), 8 (1d
and 2c), 16 (1e and 2d), and 32 (2e) allyl groups at the
periphery (Scheme 1). Likewise, metalation of the porphyrins
in the dendrimers was carried out using N,N-dimethylforma-
43
fragments. The preparation of the porphyrin macrocycles 1a
4
4
and 2a was carried out from p-methoxybenzaldehyde or 3,5-
dimethoxybenzaldehyde in the presence of pyrrole and
propionic acid as a reaction medium (see the Supporting
46
mide (DMF) and Zn(CH COO) ·2H O (Scheme 2). With
3
2
2
B
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Article
Scheme 3. Hydrosilylation Reaction To Obtain Dendrimer 1e -MeCb
Zn
the aim of obtaining high-boron-rich porphyrin-cored den-
drimers, we have selected some of these dendritic structures,
either free base or zinc porphyrins, to be functionalized with
carboranyl derivatives via catalytic hydrosilylation reactions.
This approach has already been used before by our group and
represents a versatile and efficient methodology to introduce a
1
5
large number of boron atoms into a molecule. The
carboranylsilane 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-
3
2
2
2
3 2
C B H was used as the hydrosilylating agent; this is a suitable
2
10 10
choice because this precursor is obtained in a fast way and with
high yield and has shown to be very efficient in previous
12
hydrosilylation reactions.
To functionalize the periphery of the different generations of
porphyrin-cored dendrimers, hydrosilylation reactions of the
terminal allyl groups with carboranylsilane were carried out. All
57
reactions were catalyzed by Karstedt’s catalyst with the
purpose of controlling the regioselectivity of the reaction to
obtain the desired β isomers (Scheme 3). Nevertheless, for the
different dendrimers, a large number of experiments were
performed to find the optima and specific conditions in terms
of the stoichiometry, solvent, temperature, and time of reaction.
The synthesis of compound 1c-MeCb (see Figure S1 in the SI)
was performed in a minimum volume of CH Cl , while the
2
2
syntheses of 1d-MeCb (Figure 1) and 1d -MeCb were carried
Zn
out in CHCl using a ratio of dendrimer/hydrosilylating agent
3
of 1:1.5 at 50 °C for 5 h in the presence of Karstedt’s catalyst
(
see Scheme 3 as an example of the synthesis of 1e -MeCb).
Zn
In the case of compound 2c-MeCb, a higher ratio of
carboranylsilane, 1:2, was necessary. To prepare higher
generations of dendrimers, 1e -MeCb, 2d -MeCb, and
Zn
Zn
2
eZn-MeCb (see Figure 1), 1,4-dioxane was used as the solvent
Figure 1. Structural representation of some carboranyl-containing
porphyrin-cored dendrimers.
because the starting dendrimers were not soluble or the
reaction did not work well in other solvents, allowing an
increase of the temperature. Besides, a higher ratio of
carboranylsilane corresponding to a 100% excess was required
for complete hydrosilylation of all terminal allyl groups (16 or
dendrimers; also important is monitoring of the O−CH
2
resonance (H-15 in Figure 2) because after functionalization
the signal is shifted to lower frequencies. The preparation of
pure compounds is a requirement for the development of
compounds especially for biological applications. Therefore,
because of the presence of Karstedt’s catalyst, a further
purification of the functionalized molecules by thin-layer
32; Scheme 3).
Hydrosilylation reactions were monitored by 1H NMR
spectroscopy to determine completion of the reaction upon the
disappearance of the allyl proton resonances of the starting
C
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Inorganic Chemistry
Article
1
Figure 2. H NMR spectra of dendrimer 1e -MeCb before and after functionalization with carborane clusters.
Zn
chromatography (TLC) was necessary. This made it possible to
recover almost all of the excess carboranylsilane used in the
reactions. After that, all carboranyl-containing dendrimers were
isolated in excellent yields, in the range 60−88%. Remarkably,
reactions with zinc porphyrin cored dendrimers gave higher
yields after functionalization with the carboranylsilanes than
those from metal-free porphyrins. Indeed, some metal-free
porphyrin dendrimer derivatives could not be fully function-
alized; however, this could be achieved for the metalated cores.
This may be due to coordination of the catalyst to the
porphyrinic nitrogen atoms, which produces their partial
deactivation.
second-generation dendrimers, and H-16 and H-17 in the third-
generation dendrimers (see the SI). The H NMR spectra for
dendrimers bearing closo clusters also exhibit resonances at low
1
frequencies, in the −0.11 to −0.08 ppm range for Si-CH
3
protons. In addition, all nonmetalated dendrimers show one
resonance near −2.70 ppm due to the two NH protons of the
porphyrinic core. The 13C{ H} NMR spectra show resonances
attributed to the aromatic signal of the dendron, from 160.5 to
100.0 ppm for all compounds. After functionalization with
carboranes, dendrimers show resonances in the region from
84.0 to 74.6 ppm attributed to Ccluster. The resonances for the
Si−CH units bonded to C appear around −3.5 ppm, whereas
1
3
c
Characterization of Carboranyl-Containing Porphyr-
the −CH − carbon atoms are displayed in the range from 40.0
2
in-Cored Dendrimers. The starting dendrimers were
to 10.0 ppm.
1
13
11
1
characterized by H and C NMR, electrospray ionization
The B{ H} NMR resonances for dendrimers decorated
with clusters appear in the characteristic closo region, from −6.0
to −11.0 ppm, showing broad overlapped bands with the
patterns 2:8. Different mass spectrometry techniques [ESI and
matrix-assisted laser desorption ionization time-of-flight
(MALDI-TOF)] were also used for characterization of the
starting compounds. The formulas of the smaller dendrimers
were well established by using ESI-MS showing the molecular
ion peak; nevertheless, for the largest dendrimers, neither the
ESI nor the MALDI-TOF mass spectra were useful, as
important fragmentation was observed. A similar fragmentation
had been previously observed for other boron-containing large
(
(
ESI-MS), and the signals were assigned from two-dimensional
2D) HSQC experiments. The H NMR spectra showed
1
signals assigned to the core (H-β) and NH from 8.85 to 9.00
ppm and from −2.69 to −2.87 ppm, respectively; these NH
signals disappear in the corresponding dendrimers with the zinc
core, and the allylic signals appear in the range from 5.16 to
1
3
6
.25 ppm. Likewise, the C NMR spectra show signals at
1
31.2−133.2 ppm (C-β) and 119.9−120.9 ppm (meso-C)
corresponding to the core. The signals for the allyl groups
appear at 69.0−70.5 ppm (CH ), 133.2−133.6 ppm (CH
2
CH ), and 117.9−118.2 ppm (CHCH ). The structures of
2
2
1
15,17,18
carboranyl-containing dendrimers were established by IR, H,
molecules.
1
3
1
11
11
1
C{ H}, B, and B{ H} NMR, and elemental analysis. The
Experimental Diffusion Coefficients and Estimated
Hydrodynamic Radius of Dendrimers. Diffusion NMR
experiments have been used to get an estimation of the overall
molecular size of a set of six porphyrin-cored aryl ether
dendrimers. We have compared dendrimers of different
generations before and after functionalization with carboranes
(2c, 2c-MeCb, 2d , 2d -MeCb, 2e , and 2e -MeCb). To
IR spectra of the carboranyl-containing dendrimers show the
typical ν(B−H) strong bands for closo clusters around 2580
−1
−1
cm . The absence of a band at 2112 cm corresponding to
ν(Si−H) from the silane function of the carboranylsilane
1
indicates the total hydrosilylation of the alkene. In the H NMR
spectra, resonances in the range of 6.25−5.16 ppm due to the
allyl protons have disappeared after hydrosilylation reaction,
confirming anti-Markovnikov addition of the μ-SiH function to
the double bonds and, subsequently, complete peripheral
functionalization. In the latter compounds, the presence of new
Zn
Zn
Zn
Zn
our knowledge, these are the first boron cluster-containing
dendrimers characterized by this technique. Diffusion experi-
ments are displayed using a DOSY (Diffusion-Ordered NMR
SpectroscopY) representation, where the chemical shift is
58−60
proton resonances in the −CH − region corroborates their
plotted versus the diffusion coefficient (D) in a 2D map.
2
formation. These resonances correspond to protons H-6 and
In addition, diffusion experiments have the advantage of
allowing measurement of the diffusion coefficient and
H-7 in first-generation dendrimers, H-11 and H-12 in the
D
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Inorganic Chemistry
Article
estimation of the hydrodynamic radius (R ) according to the
65%, and an increase of the estimated R by ∼50−60%. The
H
H
Stokes−Einstein equation over a wide range of molecular
hydrodynamic radii (R ) values from this work are in good
H
6
1
weights (MW), being a complementary tool to confirm the
agreement with the sole result on these parameters obtained for
phenyl-terminated porphyrin-cored aryl ether dendrimers from
other methodology (global analysis of the fluorescence
successful functionalization of our dendrimers. Figure 3 shows
62
anisotropy decay). It has been reported that the D value of
a given known species or the MW from an unknown
compound can be roughly predicted based on the relationship
log(D) = a log(MW) + b
(2)
where a and b are two coefficients that depend on the solvent
and sample concentration with average values of about a =
63
−
0.62 and b = −7.49 for a CDCl solution. In general, eq 2
3
works well for the smaller dendrimers and shows some
deviations for the larger ones, which is attributed to a major
relative degree of molecular folding. This is in agreement with
our experimental data represented in the curve of Figure 3.
Photophysical Properties of Dendrimers. The UV−vis
spectra in CHCl of the starting dendrimers are similar to those
3
64
in tetraphenylporphyrin (TPP), with a maximum absorption
for the Soret band from 422 to 423 nm, which is red-shifted by
1
−2 nm when the core is metalated (Figure S3 in the SI and
Figure 3. Diffusion coefficients (D) from DOSY experiments versus
molecular weights (MW).
Table 2). They show molar extinction coefficients (ε) between
Table 2. Absorption Data of Dendrimers before and after
Functionalization with Carborane Clusters
the experimental D values of dendrimers as a function of their
MW values. The strong correlation between D and MW of the
different dendrimers is remarkable, with a rough experimental
dependence according to
5
dendrimer
ε × 10−
λ Soret band
Q band
1
Q band
2
1
c
3.43
3.43
3.63
3.80
2.40
2.68
4.30
2.61
3.03
3.32
4.97
3.49
2.52
5.18
9.50
3.38
5.64
422
423
423
422
423
423
423
424
423
425
423
422
422
423
424
424
423
519
519
519
515
516
517
550
551
549
550
519
513
514
547
550
550
551
556
556
559
548
552
553
a
1
1
2
2
2
1
d
D /D = (MW /MW )
(1)
A
B
B
A
e
where a ∼ 0.4−0.5. The simple correlation between D and MW
allows for the determination of a calibration curve that could
also be applied to a wide range of related compounds under the
same conditions of temperature and solvent. To prove this, we
have run additional DOSY experiments for dendrimers 1eZn
c
d
e
dZn
1eZn
2dZn
and 1e -MeCb, which have shown that their D values fit well
Zn
in the calibration curve (Table 1 and Figure 3). The
2
1
eZn
c-MeCb
556
550
550
Table 1. Diffusion Coefficients and Hydrodynamic Radii
Determined by DOSY Experiments for Eight Different
Dendrimers
1d-MeCb
2c-MeCb
2dZn-MeCb
1
eZn-MeCb
eZn-MeCb
molecular weight
(MW)
diffusion
coefficient (D)
hydrodynamic radii
2
dendrimer
(R , Å)
H
5.25 × 10−10
1dZn-MeCb
2
c
1063.3
3131.1
2420.9
6559.9
5014.0
13290.7
2845.1
6999.4
7.67
12.7
11.6
17.2
15.3
23.2
13.3
20.2
1.60
−
10
10
10
10
10
10
10
9
2
2
2
2
2
1
1
c-MeCb
3.16 × 10
dZn
3.47 × 10−
2.40 × 10 and 4.30 × 10 M. Typical Q bands were also
5
5
−
dZn-MeCb
eZn
2.34 × 10
observed in all starting dendrimers: the Q band was observed
1
2.63 × 10−
from 515 to 519 nm for free-base porphyrin dendrimers,
whereas for metalated porphyrin dendrimers, this band appears
between 549 and 551 nm, which is around 33 nm red-shifted
−
eZn-MeCb
eZn
1.74 × 10
3.02 × 10−
−
eZn-MeCb
2.00 × 10
(Table 2). As is usual, the Q band was only observed for
2
2.51 × 10−
CDCl3
nonmetalated porphyrin dendrimers, in the range from 548 to
5
59 nm. The excitation and emission spectra of starting
corresponding RH values have been calculated assuming that
dendrimers in CHCl are similar to isolated base-free TTP and
3
dendrimers are spherical (Table 1). Thus, when R for each
generation of dendrimer is compared before and after
zinc tetraphenylporphyrin (Table 3 and Figure 4). When free-
base porphyrin dendrimers were irradiated at 422 nm, high-
intensity emission bands of around 650−658 nm were observed
in the emission spectra, whereas other bands of lower intensity
were found to be close to 720 nm. On the other hand, for zinc-
metalated porphyrin dendrimers, the emission maximum bands
are those of low energy at around 650 nm, while the emission
bands near 600 nm exhibit lower intensity. The UV−vis
H
functionalization, it is observed that the R value is higher for
H
those dendrimers containing carborane clusters. Obviously, the
estimated R values also enlarge in a consistent manner when
H
the dendrimer generation is increased. As a general trend, it is
observed that full functionalization implies an average increase
of the MW by a factor about 2.5−3, a decrease of D by ∼60−
E
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Table 3. Emission Data of Dendrimers before and after
Functionalization with Carborane Cages
observed between 649 and 657 nm, whereas for zinc porphyrin
cored dendrimers, two emission bands are observed, with
maxima in the range of 596−604 nm, 4−5 nm blue-shifted with
respect to the starting dendrimers (Table 3). As was expected,
the encapsulation of emitting porphyrins using poly(aryl ether)
dendritic structures does not cause an enhancement of their
luminescent properties. In the dendrimers reported here, the
size of the dendrimer framework has little influence on the
dendrimer
λmax Em 1
λmax Em 2
1
c
657
657
658
650
651
650
602
602
596
601
657
656
649
596
604
599
603
724
723
724
715
716
717
649
650
645
646
711
711
704
643
644
641
645
1
1
2
2
2
1
1
2
2
1
1
2
2
1
2
1
d
e
c
d
66
fluorescence properties of the core porphyrins, and the fact
e
that the carboranyl-containing dendrimers show a behavior
similar to that of the starting ones without boron clusters
indicates that the presence of the peripheral carborane units
does not have a major influence on the photophysical
properties of the porphyrin core.
dZn
eZn
dZn
eZn
c-MeCb
d-MeCb
c-MeCb
dZn-MeCb
eZn-MeCb
eZn-MeCb
dZn-MeCb
CONCLUSIONS
■
A set of new boron-enriched porphyrin-cored aryl ether
dendrimers have been obtained by regioselective hydro-
silylation of allyl terminal groups with the adequate
carboranylsilane. The synthesis of these dendrimers is highly
controlled, and the reaction conditions are optimized for each
one. Dendrimers have been fully characterized by IR and NMR
spectroscopy as well as elemental analysis. In addition, the
diffusion coefficients (D) of some dendrimers before and after
functionalization with carborane derivatives have been
determined by DOSY experiments, and the hydrodynamic
absorption and emission spectra of carboranyl-containing
porphyrin-cored dendrimers in CHCl are shown in Figures
3
5
and 6, respectively. The UV−vis absorption spectra of
carboranyl-functionalized dendrimers are similar to those of the
noncarboranyl functionalized ones with Soret bands at 422−
4
24 nm, Q bands at 514−550 nm, and Q bands at 550−556
1
2
radius (R ) has been calculated using the Stokes−Einstein
H
nm, in some cases blue-shifted by 1−6 nm (see Table 2).
Neither the Soret nor the Q bands undergo major changes
upon an increase in the dendrimer generation or the number of
boron clusters on the periphery. Nevertheless, the zinc
porphyrin cored dendrimers exhibit absorption maxima at
around 423−424 nm, and a small red shift of ∼1−2 nm of the
Soret band is observed as the generation number increases.
This effect is typical for these kinds of porphyrin-cored
dendrimers, for which Aida et al. suggested that the red shift is
associated with the encapsulation degree of the porphyrin into
equation. A notable correlation between D and MW of
dendrimers has been found that can be extrapolated to a
wide range of related compounds under the same conditions of
temperature and solvent to predict their overall size and folding
properties. This technique can be used as a complementary tool
to confirm the successful functionalization of our dendrimers
with carboranes and could possibly be extended to other
functionalities. The UV−vis spectra show the characteristic
Soret and Q bands for the porphyrin, which are not largely
affected by the dendritic branches or the number of carborane
clusters. The emission behavior, before and after functionaliza-
tion of dendrimers, indicates that there are no changes in the
photoluminescence (PL) properties after the incorporation of
cages, so that the introduction of carborane clusters to the
dendrimeric skeleton does not alter their PL behavior, a facet
6
5
the dendrimer, whereas Frec
́
het et al. proposed that the red
shift of the Soret band is an indication of weak interactions
62
between the core and branches. If we compare the emission
spectra of carboranyl-containing dendrimers with the unmodi-
fied one, it is noticed that no remarkable differences are
observed. For nonmetalated dendrimers, emission maxima are
Figure 4. Emission spectra of starting porphyrin-cored dendrimers in CHCl (λex = 422 nm): free-base dendrimers (left); metalated dendrimers
3
(
right).
F
DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 5. UV−vis spectra in CHCl of carboranyl-containing dendrimers: free-base dendrimers (left); metalated dendrimers (right).
3
Figure 6. Emission spectra of carboranyl-containing dendrimers in CHCl (λ = 422 nm): free-base dendrimers (left); metalated dendrimers (right).
3
ex
that can be important to benefitting from the individual
property of the porphyrin and carborane clusters.
interest. Elemental analyses were performed using a Carlo Erba
EA1108 microanalyzer.
Materials. All reactions were performed under an atmosphere of
dinitrogen employing standard Schlenk techniques. The solvents were
reagent grade and were purified by distillation from the appropriate
EXPERIMENTAL SECTION
■
drying agents before use. The pyrrole, p-CH OC H CHO, 3,5-
Instrumentation. IR spectra were measured on PerkinElmer
Spectrum 400 FT-IR/FT-FIR and Shimadzu FTIR-ATR-8300
3
6
4
(
CH O) C H CHO, CH CH COOH, 48% HBr, allyl bromide,
3 2 6 4 3 2
1
LiAlH , SOCl , C H N, and K CO were provided by Sigma-Aldrich,
spectrophotometers (units are reciprocal centimeters). H NMR
4 2 5 5 2 3
(
300.13 and 400 MHz) and 13C{ H} (75.47 and 100.5 MHz) spectra
1
glacial CH COOH was provided by J. T. Baker, and 1-CH -1,2-closo-
3 3
C B H was supplied by Katchem Ltd. (Prague) and used as
were recorded using Varian Unity Inova 400 MHz and Bruker ARX
2 10 11
00 spectrometers. The 11B NMR (96.29 MHz) spectra were recorded
received. Karstedt’s catalyst (9.21% Pt) was purchased from Johnson
3
Matthey. The n-BuLi solution (1.6 M in hexanes) and 1-(CH )-2-
3
on a Bruker ARX 300 spectrometer. All experiments were done with
[
CH CH CH Si(CH ) H]-1,2-closo-C B H were prepared accord-
2 2 2 3 2 2 10 10
12 43 44 48 49
concentrations between 15 and 20 mg/mL at 25 °C. Chemical shifts
1
ing to the literature. Compounds 1a, 2a, 1b, 2b, Br-dendron-
1,
(
ppm) are relative to Si(CH ) for H (of residual proton; 7.25 ppm)
3
4
50−53
54,55
13
11
and Br-dendron-2,
were prepared following literature
and C (77.23 ppm) in CDCl . Chemical shift values for B NMR
3
processes; in some specific cases, little modification was done (see the
SI). UV−vis spectroscopic data for all of these are in agreement with
the data reported in the literature.
spectra were referenced to external BF ·OEt . Chemical shifts are
3
2
reported in units of parts per million downfield from the reference, and
all coupling constants are reported in Hertz. Mass spectra were
obtained from a Thermo-Electron DFS spectrometer instrument by an
electron impact (EI) ionization technique, and the AB SCIEX 4800
Plus MALDI TOF/TOF analyzer has the highest sensitivity available
in MS and MS/MS mode. UV−vis spectra were recorded on
PerkinElmer Lambda 900 and Shimadzu UV-1700 Pharmaspec
spectrophotometers using 1.0 cm cuvettes. The fluorescence emission
spectra of the starting dendrimers were recorded on a Varian Cary
Eclipse fluorescence spectrometer. The fluorescence emission spectra
of the carboranyl-containing dendrimers were recorded on a
PerkinElmer LS-45 (230 V) fluorescence spectrometer. Samples
were prepared in spectroscopic-grade solvents and adjusted to a
response within the linear range. No fluorescent contaminants were
detected upon excitation in the wavelength region of experimental
Procedure for the Preparation of Dendrimers 1c−1e and
2
c−2e. A round-bottomed flask equipped with a condenser and a
magnetic stirring bar was charged with porphyrin 1b or 2b, allyl
bromide, or Br-dendron-1 or Br-dendron-2, with K CO and a
2
3
catalytic amount of KI, using acetone as the solvent. The mixture was
refluxed for 16 h, monitoring the reaction by TLC. After that, the
reaction mixture was filtered and the volatiles were evaporated under
vacuum. The solid product was washed with hexane and methanol to
remove impurities to obtain dendrimers 1c with 4, 1d and 2c with 8,
1e and 2d with 16, and finally 2e with 32 allyl groups present in the
periphery of the dendrimers.
meso-Tetrakis(4-allyloxyphenyl)porphyrin (1c). The title com-
pound was prepared with 1b (1.00 g, 1.50 mmol), allyl bromide (1.43
g, 11.70 mmol), K CO (2.44 g), and a catalytic amount of KI in
2
3
G
DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
acetone. Compound 1c was obtained as a purple solid (1.07 g, 87%
8.87 (s, 8H, H-β), 8.13 (d, 8H, J = 8.5 Hz, H-2), 7.35 (d, 8H, J = 8.5
Hz, H-3), 6.88 (d, 8H, J = 2.2 Hz, H-7), 6.66 (d, 16H, J = 2.3 Hz, H-
12), 6.64 (t, 4H, J = 2.2 Hz, H-9), 6.48 (t, 8H, J = 2.3 Hz, H-14), 6.05
(ddt, 16H, J = 17.3, 10.5, and 5.3 Hz, H-16), 5.41 (ddt, 16H, J = 17.3,
1.6, and 1.5 Hz, H-17a), 5.27 (ddt, 16H, J = 10.5, 1.5, and 1.4 Hz, H-
17b), 5.28 (s, 8H, H-5), 5.06 (s, 16H, H-10), 4.54 (dt, 32H, J = 5.3
1
yield). Mp: 250−252 °C. H NMR (CDCl , 300 MHz): δ 8.85 (s, 8H,
3
H-β), 8.09 (d, 8H, J = 8.5 Hz, H-2), 7.26 (d, 8H, J = 8.5 Hz, H-3), 6.25
(
ddt, 4H, J = 16.5, 10.5, and 5.1 Hz, H-6), 5.59 (dd, 4H, J = 16.5 and
1
=
1
1
3
.2 Hz, H-7a), 5.43 (dd, 4H, J = 10.5 and 1.5 Hz, H-7b), 4.78 (d, 8H, J
13
5.1 Hz, H-5), −2.75 (s, 2H, NH). C NMR (CDCl , 75.5 MHz): δ
3
13
58.6 (C-4), 135.8 (C-2), 135.0 (C-1), 133.6 (C-6), 131.2 (C-β),
19.9 (meso-C), 118.2 (C-7), 113.2 (C-3), 69.3 (C-5). IR (KBr): ν
319 (N−H), 1605 (CC), 1506, 1241 (C−O), 1224, 1175, 803
and 1.5 Hz, H-15), −2.78 (s, 2H, NH). C NMR (CDCl , 75.5
3
MHz): δ 160.4 (C-8), 160.2 (C-13), 158.8 (C-4), 139.7 (C-6), 139.4
(C-11), 135.9 (C-2), 135.2 (C-1), 133.3 (C-16), 133.2 (C-β), 119.9
(meso-C), 118.0 (C-17), 113.3 (C-3), 106.9 (C-7), 106.5 (C-12),
102.0 (C-9), 101.6 (C-14), 70.5 (C-5), 70.4 (C-10), 69.2 (C-15). IR
(KBr): ν 3316 (N−H), 1596 (CC), 1507, 1450, 1240, 1150, 1046
−1
+
(
C−H), 739 cm . MS [m/z (%)]: [M + H] 839 (25), 838 (19), 391
(
12), 307 (15), 192 (25), 154 (100), 136 (70), 95 (74), 69 (94). UV−
−1
−1
vis (CHCl ): λ = 422 nm (ε = 342680 M cm ).
3
max
−1
meso-Tetrakis(3,5-diallyloxyphenyl)porphyrin (2c). The title
compound was prepared from 2b (1.00 g, 1.35 mmol), allyl bromide
(C−O), 831 (C−H), 802, 731 cm . MS (MALDI): m/z 2785. UV−
−1 −1
vis (CHCl ): λ = 423 nm (ε = 362830 M cm ).
3
max
(
1.30 g, 10.7 mmol), K CO (3.20 g, 23.2 mmol), and KI in acetone.
meso-Tetrakis[3,5-[3,5-bis(3,5-bis(allyloxy)benzyloxy)-
dibenzyloxy]phenyl]porphyrin (2e). The title compound was
obtained from 2b (0.18 g, 0.24 mmol), Br-dendron-2 (1.10 g, 1.90
2
3
Compound 2c was obtained as a purple solid, (1.20 g, 84% yield). Mp:
2
1
05−207 °C. H NMR (CDCl , 400 MHz): δ 8.93 (s, 8H, H-β), 7.42
3
(
d, 8H, J = 2.4 Hz, H-2), 6.95 (t, 4H, J = 2.4 Hz), 6.14 (ddt, 8H, J =
7.2, 10.5, and 5.3 Hz, H-6), 5.49 (ddt, 8H, J = 17.2, 1.6, and 1.2 Hz,
H-7a), 5.33 (ddt, 8H, J = 10.5, 1.5, and 1.2 Hz, H-7b), 4.71 (dt, 16H, J
mmol), and K CO (81.00 g, 5.8 mmol) in the presence of KI in
2 3
1
acetone. The solid obtained was purified by column chromatography
using a mixture of hexane/acetone (8:2). Compound 2e was obtained
13
1
=
5.3 and 1.2 Hz, H-5), −2.85 (s, 2H, NH). C NMR (CDCl , 75.5
as a deep-purple oil (0.52 g, 58% yield). H NMR (CDCl
3
, 400 MHz):
3
MHz): δ 158.0 (C-3), 144.2 (C-1), 133.4 (C-6), 131.3 (C-β), 120.0
δ 8.91 (s, 8H, H-β), 7.49 (s, 8H, H-2), 7.05 (s, 4H, H-4), 6.73 (s, 16H,
H-7), 6.54 (s, 8H, H-9), 6.51 (s, 32H, H-12), 6.37 (s, 16H, H-14),
5.93 (ddt, 32H, J = 17.3, 10.5, and 5.2 Hz, H-16), 5.29 (dt, 32H, J =
17.3 and 1.3 Hz, H-17a), 5.17 (dt, 32H, J = 10.5 and 1.1 Hz, H-17b),
5.12 (s, 16H, H-5), 4.91 (s, 32H, H-10), 4.40 (d, 64H, J = 5.2 Hz, H-
(meso-C), 118.2 (C-7), 115.0 (C-2), 101.8 (C-4), 69.4 (C-5). IR
−1
(
KBr): ν 3317 (N−H), 1588 (CC), 1506, 1290 (C−O) cm . MS
+
[
m/z (%)]: [M + H] 1063. UV−vis (CHCl ): λ = 422 nm (ε =
3
max
−1
−1
3
80165 M cm ).
meso-Tetrakis[4-[3,5-bis(allyloxy)benzyloxy]phenyl]porphyrin
1d). The title compound was obtained from 1b (0.50 g, 0.74 mmol),
Br-dendron-1 (0.70 g, 2.95 mmol), K CO (1.22 g, 8.84 mmol), and
13
15), −2.83 (s, 2H, NH). C NMR (CDCl , 100 MHz): δ 160.3 (C-
3
(
8), 160.1 (C-13), 158.2 (C-3), 139.3 (C-11), 136.8 (C-6), 133.3 (C-
16), 117.9 (C-17), 115.3 (C-2), 106.9 (C-7), 106.3 (C-12), 102.1 (C-
4, C-9), 101.6 (C-14), 70.5 (C-5), 70.2 (C-10), 69.0 (C-15). IR (KBr):
ν 3317 (N−H), 1594 (CC), 1507, 1450, 1296, 1150, 1046 (C−O)
2
3
KI in acetone. The solid compound was purified by column
chromatography using a mixture of hexane/acetone (8:2). The
product 1d was obtained as a purple solid (0.84 g, 77% yield). Mp:
1
−
1
−1
−1
cm . UV−vis (CHCl ): λ = 423 nm (ε = 268265 M cm ).
3
max
1
40−144 °C. H NMR (CDCl , 300 MHz): δ 8.86 (s, 8H, H-β), 8.12
Procedure for the Metalation of Compounds 1d, 1e, 2d, and
2e. Metalation of the porphyrin was carried out using conditions
reported previously. A round-bottomed flask equipped with a
condenser and a magnetic stirring bar was charged with 1d (or 1e, 2d,
3
(
=
d, 8H, J = 8.6 Hz, H-2), 7.34 (d, 8H, J = 8.6 Hz, H-3), 6.80 (d, 8H, J
2.2 Hz, H-7), 6.55 (t, 4H, J = 2.2 Hz, H-9), 6.11 (ddt, 8H, J = 17.3,
4
6
1
1
5
0.5, and 5.3 Hz, H-11), 5.47 (ddt, 8H, J = 17.3, 1.6, and 1.6 Hz, H-
2a), 5.34 (ddt, 8H, J = 10.5, 1.4, and 1.6 Hz, H-12b), 5.27 (s, 8H, H-
or 2e) and Zn(CH COO) ·2H O (the same amount in grams as the
3 2 2
13
), 4.62 (dt, 16H, J = 5.3 and 1.2 Hz, H-10), −2.76 (s, 2H, NH).
C
porphyrin) in 70 mL of DMF, and the mixture was refluxed for 30
min. After cooling to room temperature, the solid was precipitated by
the addition of cold water and washed with methanol to remove traces
of DMF.
NMR (CDCl , 75.5 MHz): δ 160.3 (C-8), 158.8 (C-4), 139.6 (C-6),
1
1
3
35.8 (C-2), 135.2 (C-1), 133.4 (C-11), 131.2 (C-β), 119.9 (meso-C),
18.1 (C-12), 113.3 (C-3), 106.6 (C-7), 101.7 (C-9), 70.5 (C-5), 69.2
(
1
1
C-10). IR (KBr): ν 3316 (N−H), 1597 (CC), 1506, 1455, 1240,
[meso-Tetrakis[4-[3,5-bis(allyloxy)benzyloxy]phenyl]-
−
1
+
171, 1019 (C−O), 802 (C−H), 735 cm . MS [m/z (%)]: [M + H]
porphyrinato]zinc(II) (1dZn). The title compound was obtained from
487 (68), 1486 (40), 1285 (20), 203 (74), 154 (100), 136 (80), 121
1b (0.70 g, 0.47 mmol) and Zn(CH
COO) ·2H O (0.70 g, 3.19
3 2 2
−1
(
70), 69 (58). UV−vis (CHCl ): λ = 423 nm (ε = 343425 M
mmol). Compound 1dZn was obtained as a purple solid (0.61 g, 83%
3
max
−1
1
cm ).
yield). Mp: 139−141 °C. H NMR (CDCl , 400 MHz): δ 8.97 (s, 8H,
3
meso-Tetrakis[3,5-[3,5-bis(allyloxy)dibenzyloxy]phenyl]porphyrin
H-β), 8.12 (d, 8H, J = 8.3 Hz, H-2), 7.33 (d, 8H, J = 8.3 Hz, H-3), 6.78
(s, 8H, H-7), 6.52 (s, 4H, H-9), 6.10 (ddt, 8H, J = 17.3, 10.5, and 5.3
Hz, H-11), 5.46 (d, 8H, J = 17.3 Hz, H-12a), 5.33 (d, 8H, J = 10.5 Hz,
(
2d). The title compound was obtained from 2b (0.50 g, 0.74 mmol),
Br-dendron-1 (1.30 g, 5.4 mmol), K CO (2.20 g, 16.2 mmol), and KI
2
3
1
3
in acetone. The solid was purified by column chromatography using a
H-12b), 5.26 (s, 8H, H-5), 4.59 (d, 16H, J = 5.3 Hz, H-10). C NMR
mixture of hexane/acetone (8:2). The product 2d was obtained as a
(CDCl , 100.5 MHz): δ 160.3 (C-8), 158.6 (C-4), 150.7 (C-α), 139.7
3
1
purple oil (0.84 g, 60% yield). H NMR (CDCl , 400 MHz): δ 8.88 (s,
(C-6), 135.8 (C-1), 135.7 (C-2), 133.4 (C-11), 132.1 (C-β), 120.9
(meso-C), 118.1 (C-12), 113.2 (C-3), 106.6 (C-7), 101.7 (C-9), 70.5
(C-5), 69.2 (C-10). IR (KBr): ν 1595 (CC), 1506, 1453, 1220,
3
8H, H-β), 7.49 (d, 8H, J = 2.2 Hz, H-2), 7.05 (t, 4H, J = 2.2 Hz, H-4),
6.67 (d, 16H, J = 2.3 Hz, H-7), 6.47 (t, 8H, J = 2.3 Hz, H-9), 5.99 (ddt,
16H, J = 17.3, 10.5, and 5.3 Hz, H-11), 5.35 (ddt, 16H, J = 17.3, 1.6,
−1
1161, 1148, (C−H), 994, 796 cm . UV−vis (CHCl ): λ = 423 nm
3
max
−
1
−1
and 1.6 Hz, H-12a), 5.21 (ddt, 16H, J = 10.5, 1.6, and 1.4 Hz, H-12b),
(ε = 430265 M cm ).
5
2
1
1
1
1
λ
.16 (s, 16H, H-5), 4.49 (dt, 32H, J = 5.3 and 1.4 Hz, H-10), −2.87 (s,
[meso-Tetrakis[3,5-[3,5-bis(allyloxy)dibenzyloxy]phenyl]-
H, NH). 13C NMR (CDCl , 100 MHz): δ 160.2 (C-8), 158.1 (C-3),
porphyrinato]zinc(II) (2dZn). The title compound was obtained from
3
44.2 (C-1), 139.3 (C-6), 133.3 (C-11), 119.9 (meso-C), 118.0 (C-
2), 115.4 (C-2), 106.5 (C-7), 101.8 (C-4, C-9), 70.5 (C-5), 69.1 (C-
0). IR (KBr): ν 3317 (N−H), 1597 (CC), 1506, 1455, 1295, 1171,
2d (0.60 g, 0.25 mmol) and Zn(CH
mmol). Compound 2dZ 1n was obtained as a purple solid (0.52 g, 85%
, 400 MHz): δ 8.99 (s, 8H,
3 2 2
COO) ·2H O (0.60 g, 2.73
yield). Mp: 65−67 °C. H NMR (CDCl
3
−
1
+
019 (C−O) cm . MS [m/z (%)]: [M ] 2360. UV−vis (CHCl ):
max
H-β), 7.49 (s, 8H, H-2), 7.03 (s, 4H, H-4), 6.66 (s, 16H, H-7), 6.45 (s,
8H, H-9), 5.99 (ddt, 16H, J = 17.2, 10.0, and 5.2 Hz, H-11), 5.34 (d,
16H, J = 17.2 Hz, H-12a), 5.21 (d, 16H, J = 10.0 Hz, H-12b), 5.14 (s,
3
−
1
−1
= 423 nm (ε = 240225 M cm ).
meso-Tetrakis[4-[3,5-bis(3,5-bis(allyloxy)benzyloxy)benzyloxy]-
phenyl]porphyrin (1e). The title compound was obtained from 1b
16H, H-5), 4.49 (d, 32H, J = 5.2 Hz, H-10). 13C NMR (CDCl , 100.5
3
(
(
0.5 g, 0.74 mmol), Br-dendron-2 (0.86 g, 1.54 mmol), and K CO3
0.46 g, 3.33 mmol) in the presence of KI in acetone. The solid
MHz): δ 160.2 (C-8), 158.0 (C-3),150.2 (C-α) 144.9 (C-1), 139.4 (C-
6), 133.3 (C-11), 132.2 (C-β), 120.9 (meso-C), 118.0 (C-12), 115.3
(C-2), 106.5 (C-7), 102.2 (C-4), 101.7 (C-9), 70.5 (C-5), 69.1 (C-
10). IR (KBr): ν 1587 (CC), 1449, 1294, 1145, 1049 (C−O), 1000,
2
obtained was purified by column chromatography using a mixture of
hexane/acetone (8:2). The product 1e was obtained as a red solid
1
−1
−1
−1
(
0.52 g, 49% yield). Mp: 53−57 °C. H NMR (CDCl , 300 MHz): δ
923 cm . UV−vis (CHCl ): λ = 424 nm (ε = 303005 M cm ).
3
3
max
H
DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
[
meso-Tetrakis[4-[3,5-bis[3,5-bis(allyloxy)benzyloxy]benzyloxy]-
135.7 (C-2), 135.0 (C-1), 131.2 (C-β), 119.7 (meso-C), 113.2 (C-3),
106.0 (C-7), 101.0 (C-9), 78.1 (C-17), 74.6 (C-18), 70.7 (C-10), 70.5
(C-5), 39.0 (C-16), 24.3 (C-15), 23.9 (C-11), 23.1 (C-19), 15.3 (C-
phenyl]porphyrinato]zinc(II) (1e ). The title compound was
Zn
obtained from 1e (0.50 g, 0.22 mmol) and Zn(CH COO) ·2H O
0.50 g, 2.73 mmol). Compound 1eZn was obtained as a purple solid
0.52 g, 85% yield). Mp: 76−78 °C. H NMR (CDCl , 400 MHz): δ
.98 (s, 8H, H-β), 8.13 (d, 8H, J = 7.9 Hz, H-2), 7.33 (d, 8H, J = 7.9
3
2
2
−1
(
(
8
12), 11.2 (C-14), −3.4 (C-13). FTIR-ATR: ν 2578 (i, B−H str) cm .
1
3
Elem anal. Calcd for C B N O Si : C, 54.05; H, 8.33; N, 1.58.
160 294 80
H
4
12
8
Found: C, 54.00; H, 8.00; N, 1.55.
2c-MeCb. The title compound was obtained from 2c (60 mg, 0.056
Hz, H-3), 6.82 (s, 8H, H-7), 6.60 (s, 16H, H-12), 6.58 (s, 4H, H-9),
6
5
5
1
1
1
1
1
1
λ
.43 (s, 8H, H-14), 6.02 (ddt, 16H, J = 17.3, 10.5, and 3.4 Hz, H-16),
.39 (d, 16H, J = 17.3 Hz, H-17a), 5.26 (d, 16H, J = 10.5 Hz, H-17b),
.22 (s, 16H, H-5), 4.99 (s, 16H, H-10), 4.50 (d, 32H, J = 3.4 Hz, H-
mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-C B H (231
3
2
2
2
3
2
2 10 10
mg, 0.896 mmol), and 15 μL of Karstedt’s catalyst in 1 mL of CHCl3
stirred at 50 °C for 5 h. The reaction mixture was purified by
preparative TLC (1:1 dichloromethane/hexane) and precipitated with
5). 13C NMR (CDCl , 100.5 MHz): δ 160.3 (C-8), 160.1 (C-13),
3
58.6 (C-4), 150.6 (C-α), 139.6 (C-6), 139.3 (C-11), 135.9 (C-1),
35.7 (C-2), 133.3 (C-16), 132.1 (C-β), 120.8 (meso-C), 117.9 (C-
7), 113.1 (C-3), 106.9 (C-7), 106.4 (C-12), 102.0 (C-9), 101.6 (C-
4), 70.4 (C-5), 70.2 (C-10), 69.1 (C-15). IR (KBr): ν 1592 (CC),
1:1 dichloromethane/ethanol, giving a purple solid (127 mg, 72%
1
yield). H NMR (CDCl , 300 MHz): δ 8.96 (s, 8H, H-β), 7.38 (s, 8H,
3
3
3
H-2), 6.91 (s, 4H, H-4), 4.11 (t, 16H, J = 6 Hz, H-7), 2.14 (t, 16H, J
= 7.5 Hz, H-13), 1.91 (s, 24H, H-16), 1.87 (m, 16H, H-8), 1.54 (m,
−1
3
3
447, 1242, 1144, 1042 (C−O), 993, 829 cm . UV−vis (CHCl ):
max
16H, H-12), 0.69 (t, 16H, J = 7.5 Hz, H-9), 0.55 (t, 16H, J = 7.5 Hz,
3
−
1
−1
11
= 423 nm (ε = 260520 M cm ).
H-11), 0.05 (s, 64H, H-10), −2.82 (br s, 2H, NH). B NMR (CDCl ,
3
1
1
[
meso-Tetrakis[3,5-[3,5-bis[3,5-bis(allyloxy)benzyloxy]-
96.7 MHz): δ −5.87 (d, 16B, J = 145 Hz), −10.77 (d, 64B, J
=
B,H
B,H
138 Hz). 13C{ H} NMR (CDCl , 75.5 MHz): δ 158.3 (C-3), 143.9
1
dibenzyloxy]phenyl]porphyrinato]zinc(II) (2e ). The title compound
Zn
3
was obtained from 2e (0.48 g, 0.1 mmol) and Zn(CH COO) ·2H O
(C-1), 131.2 (C-β), 119.9 (meso-C), 114.4 (C-2), 101.1 (C-4), 78.1
(C-14), 74.6 (C-15), 70.8 (C-7), 38.9 (C-13), 24.3 (C-12), 23.9 (C-
8), 23.1 (C-16), 15.2 (C-9), 11.2 (C-11), −3.5 (C-10). FTIR-ATR: ν
3
2
2
(
0.48 g, 2.19 mmol). Compound 2eZn was obtained as a purple solid
1
(
9
0.390 g, 80% yield). Mp: 59−61 °C. H NMR (CDCl , 400 MHz): δ
3
−1
.01 (s, 8H, H-β), 7.50 (d, 8H, J = 2.3 Hz, H-2), 7.05 (t, 4H, J = 2.3
2578 (i, B−H str) cm . Elem anal. Calcd for C H B N O Si : C,
132 270 80 4 8 8
Hz, H-4), 6.73 (d, 16H, J = 2.1 Hz, H-7), 6.54 (t, 8H, J = 2.1 Hz, H-9),
.49 (d, 32H, J = 2.2 Hz, H-12), 6.34 (t, 16H, J = 2.2 Hz, H-14), 5.91
ddt, 32H, J = 17.2, 10.5, and 5.3 Hz, H-16), 5.28 (dt, 32H, J = 17.2
and 1.6 Hz, H-17a), 5.16 (dt, 32H, J = 10.5 and 1.3 Hz, H-17b), 5.12
s, 16H, H-5), 4.91 (s, 32H, H-10), 4.38 (dt, 64H, J = 5.3 and 1.4 Hz,
50.63; H, 8.69; N, 1.79. Found: C, 51.60; H, 9.04; N, 1.65.
1d -MeCb. The title compound was obtained from 1d (31 mg,
6
(
Zn
Zn
0.020 mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-C B H
3 2 2 2 3 2 2 10 10
(62 mg, 0.240 mmol), and 15 μL of Karstedt’s catalyst in 1 mL of
(
CHCl stirred at 50 °C for 5 h. The reaction mixture was purified by
3
13
H-15). C NMR (CDCl , 100.5 MHz): δ 160.3 (C-8), 160.0 (C-13),
preparative TLC (acetonitrile) and precipitated with 1:1 dichloro-
3
1
1
1
2
7
1
58.0 (C-3), 150.1 (C-α), 144.9 (C-1), 139.4 (C-6), 139.2 (C-11),
33.2 (C-16), 132.2 (C-β), 120.8 (meso-C), 117.8 (C-17), 115.2 (C-
), 106.8 (C-7), 106.3 (C-12), 101.9 (C-4 and C-9), 101.5 (C-14),
0.5 (C-5), 70.2 (C-10), 69.0 (C-15). IR (KBr): ν 1591 (CC),
methane/ethanol, giving a purple solid (59 mg, 82% yield). H NMR
3
(CDCl , 300 MHz): δ 9.01 (s, 8H, H-β), 8.17 (d, 8H, J = 9 Hz, H-2),
3
3
7.39 (d, 8H, J = 6 Hz, H-3), 6.80 (s, 8H, H-7), 6.51 (s, 4H, H-9), 5.31
(s, 8H, H-5), 4.03 (t, J = 6 Hz, 16H, H-10), 2.20 (t, J = 7.5 Hz, 16H,
3
3
−1
447, 1295, 1146, 1047 (C−O), 1046, 1001, 830 cm . UV−vis
H-16), 2.02 (s, 24H, H-19), 1.86 (m, 16H, H-11), 1.60 (m, 16H, H-
−
1
−1
3
3
(
CHCl ): λ = 425 nm (ε = 331535 M cm ).
15), 0.72 (t, 16H, J = 9 Hz, H-12), 0.59 (t, 16H, J = 9 Hz, H-14),
3
max
11
1c-MeCb. A 5 mL round-bottomed flask was charged with 1c (60
0.09 (s, 48H, H-13). B NMR (CDCl , 96.7 MHz): δ −5.88 (d, 16B,
3
1 1 13 1
mg, 0.072 mmol) and 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-
C B H (111 mg, 0.430 mmol) and dried under vacuum for 15 min.
The mixture was dissolved in 1 mL of dry CH Cl , and 12 μL of
Karstedt’s catalyst was added and refluxed for 5 h under nitrogen. The
volatiles were removed under pressure to obtain a brown-purple oil,
which was purified by preparative TLC (1:1 dichloromethane/hexane)
and precipitated with 1:1 dichloromethane/ethanol, giving a purple
solid (95 mg, 71% yield). H NMR (CDCl , 300 MHz): δ 8.91 (s, 8H,
JB,H = 146 Hz), −10.75 (d, 64B, J = 139 Hz). C{ H} NMR
3
2
2
2
3
2
B,H
2
10 10
(CDCl , 75.5 MHz): δ 160.6 (C-8), 158.6 (C-4), 150.5 (C-α), 140.4
3
2
2
(C-1), 139.4 (C-6), 135.5 (C-2), 131.9 (C-β), 120.8 (meso-C), 106.0
(
C-7), 101.1 (C-9), 78.1 (C-17), 74.6 (C-18), 70.7 (C-5), 70.7 (C-
1
1
0), 39.0 (C-16), 24.3 (C-15), 23.9 (C-11), 23.1 (C-19), 15.3 (C-14),
−1
1.2 (C-12), −3.4 (C-13). FTIR-ATR: ν 2578 (i, B−H str) cm .
Elem anal. Calcd for C1
H
292 80
B N O Si Zn: C, 53.10; H, 8.13; N,
60
4
12
8
1
3
1.55. Found: C, 53.38; H, 8.18; N, 1.45.
dZn-MeCb. The title compound was obtained from 2dZn (40 mg,
.0165 mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-
3
3
H-β), 8.16 (d, 8H, J(H,H) = 9 Hz, H-2), 7.30 (d, 8H, J(H,H) = 12
Hz, H-3), 4.24 (t, 16H, J = 6 Hz, H-5), 2.26 (t, 16H, J = 9 Hz, H-
2
3
3
0
3
2
2
2
3 2
1
1), 2.05 (s, 24H, H-14), 1.99 (m, 16H, H-6), 1.67 (m, 16H, H-10),
C B H (137 mg, 0.531 mmol), and 15 μL of Karstedt’s catalyst in
2
10 10
3
3
0.84 (t, 16H, J = 9 Hz, H-7), 0.66 (t, 16H, J = 9 Hz, H-9), 0.16 (s,
1
mL of 1,4-dioxane stirred at 55 °C for 5 h. The reaction mixture was
1
1
4
8H, H-8), −2.69 (br s, 2H, NH). B NMR (CDCl , 96.7 MHz): δ
3
purified by preparative TLC (70:30 acetonitrile/ethyl acetate) and
1
1
−
5.86 (d, 8B, J = 147 Hz), −10.79 (d, 32B, J = 142 Hz).
C{ H} NMR (CDCl , 75.5 MHz): δ 158.91 (C-4), 135.66 (C-2),
precipitated with 1:1 dichloromethane/ethanol, giving a purple solid
B,H
B,H
1
3
1
1
3
(95 mg, 88% yield). H NMR (CDCl , 300 MHz): δ 9.09 (s, 8H, H-
3
1
1
6
34.47 (C-1), 131.07 (C-β), 119.80 (meso-C), 112.76 (C-3), 78.11 (C-
2), 74.66 (C-13), 70.72 (C-5), 39.04 (C-11), 24.30 (C-10), 24.00 (C-
), 23.19 (C-14), 15.29 (C-7), 11.32 (C-9), −3.42 (C-8). FTIR-ATR:
β), 7.56 (s, 8H, H-2), 7.10 (s, 4H, H-4), 6.67 (s, 16H, H-7), 6.44 (s,
8H, H-9), 5.16 (s, 16H, H-5), 3.93 (br s, 32H, H-10), 2.13 (t, 32H, J
= 7.5 Hz, H-16), 1.95 (s, 48H, H-19), 1.77 (m, 16H, H-11), 1.53 (m,
3
−1
ν 2579 (i, B−H str) cm . Elem anal. Calcd for C H B N O Si : C,
16H, H-15), 0.62 (br s, 16H, H-12), 0.51 (br s, 16H, H-14), 0.01 (s,
88
150 40
4
4
4
96H, H-13). 11B NMR (CDCl , 96.7 MHz): δ −5.94 (d, 32B, J
1
=
3
5
6.43; H, 8.07; N, 2.99. Found: C, 56.82; H, 8.40; N, 2.90.
d-MeCb. The title compound was obtained from 1d (30 mg, 0.020
mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-C B H (63
3
B,H
1
13
1
1
153 Hz), −10.70 (d, 128B, J = 130 Hz). C{ H} NMR (CDCl ,
B,H
3
2
2
2
3
2
2 10 10
75.5 MHz): δ 160.5 (C-8), 158.1 (C-3), 150.1 (C-α), 144.7 (C-1),
1389.0 (C-6), 132.0 (C-β), 120.8 (meso-C), 114.9 (C-2), 106.0 (C-7),
101.5 (C-4), 101.0 (C-9), 78.1 (C-17), 74.6 (C-18), 70.6 (C-5), 70.6
(C-10), 38.9 (C-16), 24.2 (C-15), 23.8 (C-11), 23.1 (C-19), 15.2 (C-
mg, 0.244 mmol), and 10 μL of Karstedt’s catalyst in 1 mL of
CHCl stirred at 50 °C for 5 h. The reaction mixture was purified by
preparative TLC (acetonitrile) and precipitated with 1:1 ether/
ethanol, giving a purple solid (46 mg, 64% yield). H NMR (CDCl ,
3
8
3
1
−1
12), 11.1 (C-14), −3.5 (C-13). FTIR-ATR: ν 2578 (i, B−H str) cm .
3
3
00 MHz): δ 8.92 (s, 8H, H-β), 8.18 (d, 8H, J = 6 Hz, H-2), 7.41 (d,
Elem anal. Calcd for C2 H B N O Si Zn: C, 50.53; H, 8.54; N,
76 556 160 4 24 16
3
H, J = 6 Hz, H-3), 6.82 (s, 8H, H-7), 6.54 (s, 4H, H-9), 5.32 (s, 8H,
0.85. Found: C, 51.03; H, 8.67; N, 0.78.
3
3
H-5), 4.05 (t, 16H, J = 6 Hz, H-10), 2.21 (t, 16H, J = 7.5 Hz, H-16),
1e -MeCb. The title compound was obtained from 1e (25 mg,
Zn
Zn
2
.02 (s, 24H, H-19), 1.87 (m, 16H, H-11), 1.61 (m, 16H, H-15), 0.73
0.0088 mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-
C B H (72 mg, 0.279 mmol), and 20 μL of Karstedt’s catalyst in
2 10 10
3 2 2 2 3 2
3
3
(
t, 16H, J = 9 Hz, H-12), 0.60 (t, 16H, J = 9 Hz, H-14), 0.10 (s, 48H,
11
H-13), −2.70 (br s, 2H, NH). B NMR (CDCl , 96.7 MHz): δ −5.91
1 mL of 1,4-dioxane stirred at 60 °C for 5 h. The reaction mixture was
3
1
1
13
1
(
d, 16B, J = 148 Hz), −10.78 (d, 64B, J = 140 Hz). C{ H}
purified by preparative TLC (acetonitrile) and precipitated with 1:1
B,H
B,H
1
NMR (CDCl , 75.5 MHz): δ 160.6 (C-8), 158.7 (C-4), 139.4 (C-6),
dichloromethane/ethanol, giving a purple solid (42 mg, 69% yield). H
3
I
DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
3
NMR (CDCl , 300 MHz): δ 9.05 (s, 8H, H-β), 8.21 (d, 8H, J = 9 Hz,
DOSY spectra was obtained by using the DOSY protocol included into
the Bruker TOPSPIN software package (version 1.3).
3
3
H-2), 7.43 (d, 8H, J = 6 Hz, H-3), 6.96 (s, 8H, H-7), 6.71 (s, 4H, H-
9
1
2
0
9
1
7
1
1
1
7
), 6.67 (s, 16H, H-12), 6.47 (s, 8H, H-14), 5.34 (s, 8H, H-5), 5.11 (s,
6H, H-10), 3.98 (t, 32H, J = 6 Hz, H-15), 2.18 (t, 32H, J = 9 Hz, H-
3
3
ASSOCIATED CONTENT
■
1), 2.00 (s, 48H, H-24), 1.82 (m, 32H, H-16), 1.58 (m, 32H, H-20),
*
S
Supporting Information
3
3
.69 (t, 32H, J = 9 Hz, H-17), 0.56 (t, 32H, J = 9 Hz, H-19), 0.07 (s,
1
13
Procedures, H, C, and HSQC NMR spectra for starting
6H, H-18). 11B NMR (CDCl , 96.7 MHz): δ −5.89 (d, 32B, J
48 Hz), −10.77 (d, 128B, J = 140 Hz). C{ H} NMR (CDCl ,
1
=
3
B,H
1
13
1
13
1
dendrimers, H and C NMR spectra for carboranyl-containing
dendrimers, molecular structures for carboranyl-containing
dendrimers, UV−vis spectra for starting dendrimers, and 2D
DOSY spectra for dendrimers. This material is available free of
charge via the Internet at http://pubs.acs.org.
B,H
3
5.5 MHz): δ 160.5 (C-13), 160.4 (C-8), 158.6 (C-4), 150.5 (C-α),
39.6 (C-6), 139.1 (C-11), 135.7 (C-1), 135.5 (C-2), 1312.0 (C-β),
20.8 (meso-C), 113.0 (C-3), 106.7 (C-7), 106.0 (C-12), 101.8 (C-9),
01.0 (C-14), 78.2 (C-22), 74.7 (C-23), 70.6 (C-15), 70.3 (C-10),
0.3 (C-5), 39.0 (C-21), 24.3 (C-20), 23.8 (C-16), 23.1 (C-24), 15.2
(
C-17), 11.2 (C-19), −3.4 (C-18). FTIR-ATR: ν 2580 (i, B−H str)
AUTHOR INFORMATION
Corresponding Author
E-mail: rosario@icmab.es. Fax: (+34) 935805729.
Notes
The authors declare no competing financial interest.
J.C.-G. is enrolled in the UAB Ph.D. program, and E.X.-F. is
enrolled in the UNAM Ph.D. program.
■
*
−1
cm . Elem anal. Calcd for C
H B N O Si Zn: C, 52.34; H,
05 583 160 4 28 16
3
8
.40; N, 0.80. Found: C, 53.06; H, 8.53; N, 0.75.
eZn-MeCb. The title compound was obtained from 2eZn (38 mg,
.0076 mmol), 1-CH -2-[CH CH CH (CH ) SiH]-1,2-closo-
2
0
3
2
2
2
3 2
C B H (109 mg, 0.422 mmol), and 17 μL of Karstedt’s catalyst in
1
purified by preparative TLC (acetonitrile) and precipitated with 1:1
dichloromethane/ethanol, giving a purple solid (74 mg, 74% yield). H
2
10 10
‡
mL of 1,4-dioxane stirred at 60 °C for 5 h. The reaction mixture was
1
NMR (CDCl , 300 MHz): δ 9.11 (s, 8H, H-β), 7.56 (s, 8H, H-2), 7.12
ACKNOWLEDGMENTS
This work has been supported by the Junta de Andalucıa
programa Proyectos de Excelencia (P11-FQM-8229) and
́
Ministerio de Economıa y Competitividad (CTQ2013-44670-
R and CTQ2012-32436). J.C.-G. thanks the CSIC for an
Intramural grant. E.X.-F. thanks CONACYT for a Ph.D.
́
fellowship (211329) and Programa de Cooperacion Cientıfica
́
UNAM-CSIC and CONACYT for financial support.
3
■
(
s, 4H, H-4), 6.80 (s, 16H, H-7), 6.55 (s, 8H, H-9), 6.53 (s, 32H, H-
́
,
1
3
1
0
9
1
2), 6.36 (s, 8H, H-14), 5.17 (br s, 8H, H-5), 4.95 (br s, 32H, H-10),
.85 (br s, 64H, H-15), 2.11 (br s, 64H, H-21), 1.93 (s, 96H, H-24),
.71 (m, 64H, H-16), 1.52 (m, 64H, H-20), 0.58 (br s, 64H, H-17),
11
.50 (br s, 64H, H-19), −0.01 (s, 192H, H-18). B NMR (CDCl ,
3
1
1
6.7 MHz): δ −6.01 (d, 64B, J = 153 Hz), −10.69 (d, 256B, J
=
B,H
B,H
23 Hz). 13C{ H} NMR (CDCl , 75.5 MHz): δ 160.4 (C-13), 158.7
1
3
(
C-8), 158.0 (C-3), 150.1 (C-α), 139.3 (C-6), 139.0 (C-11), 132.2 (C-
β), 107.5 (C-2), 106.7 (C-7), 105.9 (C-12), 102.2 (C-4), 101.7 (C-9),
00.9 (C-14), 78.2 (C-22), 74.7 (C-23), 71.5 (C-5), 70.5 (C-15), 70.2
C-10), 38.9 (C-21), 24.3 (C-20), 23.8 (C-16), 23.1 (C-24), 15.1 (C-
1
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1132 320
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DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
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DOI: 10.1021/acs.inorgchem.5b00618
Inorg. Chem. XXXX, XXX, XXX−XXX