Hydrogen bonding induced supramolecular self-assembly of linear doubly discotic triad supermolecules

Article abstract of DOI:10.1002/asia.201000017

A series of linear doubly discotic triad supermolecules based on a porphyrin (P) core and two triphenylene (Tp) arms linked by amide bonds are synthesized. The samples are denoted as P(Tp)2. Hydrogen bonding along the P stacks is the primary driving force

Full text of DOI:10.1002/asia.201000017

FULL PAPERS
DOI: 10.1002/asia.201000017
Hydrogen Bonding Induced Supramolecular Self-Assembly of Linear Doubly
Discotic Triad Supermolecules
[
a]
[a, b]
Jianjun Miao and Lei Zhu*
Abstract: A series of linear doubly dis-
cotic triad supermolecules based on a
porphyrin (P) core and two tripheny-
lene (Tp) arms linked by amide bonds
are synthesized. The samples are de-
plays an important role. For samples
with the spacer lengths longer than or
similar to the alkyl chain lengths in the
Tp arms, P and Tp are decoupled to a
large degree. This decoupling result in
non-uniform tilt angles for P and Tp
disks along both the a- and c-axes.
Therefore, large unit cells are observed
with eight P(Tp)2 supermolecules per
cell. For a sample with the spacer
length much shorter than the alkyl
chains in the Tp arms, P and Tp are
strongly coupled. Therefore, both P
and Tp have uniform tilt angles along
the a- and c-axes. A small unit cell is
noted as P(Tp) . Hydrogen bonding
2
along the P stacks is the primary driv-
ing force for the supramolecular self-
assembly of P(Tp)2 triad supermole-
cules. Meanwhile, the degree of cou-
pling between P and Tp disks also
Keywords: hydrogen-bonding
·
porphyrins · self-assembly · super-
molecular chemistry · triphenylene
obtained with only one P(Tp) super-
2
molecule per cell.
[2,3]
Introduction
enhance the functionality of individual LC molecules,
and the resultant unique physical properties are attractive
for applications in advanced optoelectronic materials and
Supramolecular self-assembly is mainly governed by the
non-covalent interactions, such as van der Waals interac-
tions, p–p interactions, or hydrogen bonding as well as mo-
lecular shape/topology, space-filling effects, and microsegre-
[3–9]
biology.
Among LC supermolecules, calamitic polypede LC super-
[10–36]
molecules have received much research attention.
How-
[1]
gation of incompatible parts of the constituent molecules.
ever, discotic LC polypedes containing three or more discot-
ic mesogenic units have not been as extensively studied as
On the other hand, supermolecules are comprised of well-
defined, covalently linked small molecular moieties with
multi-functions, and thus represent a novel class of advanced
functional materials, which can further self-assemble into hi-
[
37,38]
calamitic LC polypedes.
tures for discotic LC polypedes have been made possible,
A variety of molecular architec-
[39–41]
[42–49]
e.g., linear,
star-shaped,
and mixed calamitic/discot-
[2]
[50–52]
erarchical structures. Liquid crystalline (LC) supermole-
cule-stabilized non-covalent interactions are particularly in-
teresting, because their supramolecular self-assembly can
ic.
For most linear and star-shaped disocotic LC poly-
pedes, a normal hexagonal columnar phase with the unit cell
dimension close to that of the parent triphenylene (Tp) and
hexa-peri-hexabenzocoronene (HBC) discotic LCs was ob-
served, suggesting that the peripheral Tp or HBC discotic
mesogens self-organized into individual LC columns regard-
less of the covalent linkages to the central core. However,
for mixed calamitic/discotic triads, unconventional meso-
scale self-assembly (e.g., nematic columnar phases) was ob-
served with a specific arrangement of the calamitic meso-
gens with respect to the LC columns.
[
a] J. Miao, Prof. L. Zhu
Polymer Program, Institute of Materials Science and Department of
Chemical, Materials and Biomolecular Engineering
University of Connecticut
Storrs, Connecticut 06269-3136 (USA)
Fax : (+1)216-368-4202
E-mail: lxz121@case.edu
[
b] Prof. L. Zhu
In addition to the shape and topology, hydrogen bonding
is another important determining factor for the supramolec-
ular self-assembly of discotic LC supermolecules. An elegant
example of hydrogen bond-induced columnar liquid crystals
Department Department of Macromolecular Science and
Engineering
Case Western Reserve University
Cleveland, Ohio 44106-7202 (USA)
(
LCs) in an otherwise non-liquid crystalline discotic mole-
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201000017.
[53–56]
cule is 1,3,5-benzenetrisamides.
A C -symmetry was ob-
3
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Chem. Asian J. 2010, 5, 1634 – 1641

served within a column, where the 1208 rotation between
neighboring benzenetrisamide molecules was stabilized by
intermolecular hydrogen-bonding along the column direc-
tion. Meanwhile, a sergeants-and-soldiers principle was pre-
cules in a previous report [one P core with four Tp arms
[64]
linked by amide bonds, denoted as P(Tp) ],
because
4
P(Tp) has a C2 symmetry and P(Tp) has a C4 symmetry.
2
4
Experimental results showed that hydrogen bonding along
[57–59]
sented by Meijer et al. in these systems.
The discotic LC
the P stacks induced crystalline phases for P(Tp) , rather
2
phases induced by hydrogen bonding showed a higher ther-
mal stability and better responses to external stimuli such as
than the discotic LC phases for P(Tp) . In addition to hydro-
gen bonding, the degree of coupling between P and Tp disks
was found important for the supramolecular self-assembly in
4
[60,61]
electric and magnetic fields.
Paraschiv et al. reported a
series of 1,3,5-benzenetrisamide with three pendent hexaal-
koxytriphenylene groups by varying the spacer length and
P(Tp) supermolecular crystals.
2
[62,63]
the Tp arm length.
Four columnar hexagonal phases
were identified in total, where intermolecular hydrogen
bonds connected the central benzene cores in such a way
that the adjacent benzene cores rotated 1208 apart, there-
fore leading to a helical orientation of the resulting colum-
Results and Discussion
Compounds 1–4 were synthesized following a four-step pro-
cedure (Scheme 1). Details and nuclear magnetic resonance
(NMR) characterization data are provided in the Experi-
mental Section below. The purity of all samples was con-
firmed by thin-layer chromatography and size-exclusion
chromatography (SEC), and narrow unimodel peaks [poly-
dispersity indices (PDI)=1.01] were obtained (see Figure 1).
2
À1 À1
nar stacks. A high mobility of 0.23 cm V
one of those Tp benzenetrisamide samples.
s
was found in
[
63]
In this work, we synthesized a series of doubly discotic
triads based on a porphyrin (P) central core and two Tp
arms linked by amide bonds. These samples, denoted as
P(Tp) , are different from the doubly discotic supermole-
2
Scheme 1. Synthesis of P(Tp)
2
triads with different spacer and alkyl chain lengths.
Thermal Behaviors and Morphology of P(Tp) Triads
2
Abstract in Chinese:
Phase transitions in samples 1–4 were first studied by differ-
ential scanning calorimetry DSC (see Figure 2), and results
are summarized in Table 1. Sample 1 showed a single crys-
À1
tallization temperature (T ) at 1858C (60 kJmol ) upon
c
cooling and a single melting temperature (T ) at 2428C
m
À1
À1
(
61 kJmol ) upon heating at 108Cmin . Sample 2 showed
a different thermal behavior from sample 1. During the first
cooling, it only exhibited a glass transition temperature (Tg)
at 458C. Upon the second heating, sample 2 showed a T at
g
5
38C,
a
cold crystallization temperature at 1318C
À1
À1
(
33.5 kJmol ), and a T at 2048C (52 kJmol ). Judging
m
from heats of transition and large undercoolings (DT=
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J. Miao and L. Zhu
FULL PAPERS
2
Figure 1. SEC differential refractive index (RI) curves for P(Tp) triads
1
–4. Polydispersity indices (PDI) are also shown for all the samples.
Figure 3. PLM micrographs of P(Tp)
2
triads (A) 1 at 1208C, (B) 2 at
room temperature, (C) 3 at 508C, and (D) 4 at room temperature.
À1
spectively. Sample 4 showed a T at 1078C (70 kJmol ) and
c
À1
a broad weak peak at 238C (27.2 kJmol ) during cooling.
Upon heating, two reverse processes were observed with a
À1
relatively broad peak at 398C (31.9 kJmol ) and a sharp T
m
À1
at 1498C (72.8 kJmol ). Judging from the magnitude of
heats of transitions, the high temperature (e.g., 908C)
phases should be crystalline. On the basis of our previous
[64]
study, the low temperature phase transitions could be at-
tributed to the C12 alkyl chain-induced crystallization. The
PLM micrograph of sample 4 at room temperature (Fig-
ure 3D) showed a sheet-like crystalline texture, which was
similar to those of samples 1 and 2. However, sample 3 ex-
hibited a much different morphology from the other three
samples, showing an irregular texture with fairly small
grains.
Figure 2. Differential scanning calorimetry (DSC) first cooling and
second heating curves for P(Tp)
2
triads 1-4. The scanning rate is
À1
1
08Cmin
.
Table 1. Phase transition temperatures (8C, above the arrow) and heats
À1
of transition (kJmol , below the arrow) for P(Tp)
2
triads 1–4. Cr=crys-
tal; g=glass; I=isotropic.
Hydrogen Bonding-Induced Supramolecular Self-Assembly
Sample
First cooling
First heating
in Linear Amide-Linked P(Tp) Triads
2
1
2
The role of hydrogen bonding in the supramolecular self-as-
sembly of amide-linked P(Tp) supermolecules was investi-
2
gated by temperature-dependent Fourier transform infrared
3
4
(
FTIR) studies, and results are shown in Figure 4A–D for
samples 1–4, respectively. Below the T , hydrogen-bonded
m
NÀH stretching and amide I C=O stretching absorption
À1
bands were observed at 3318 and 1641 cm , respectively.
À1
The appearance of the amide I band at 1641 cm was con-
T ÀT ), samples 1 and 2 should be crystalline below the T .
sistent with a trans amide conformation. Above the T , the
m
c
m
m
As shown in the polarized light microscopy (PLM) micro-
graphs for samples 1 and 2 (Figure 3 A and B, respectively),
ribbon-like, rather than spherulitic, crystalline morphology
was observed.
intensity of hydrogen-bonded NÀH and amide I bands sub-
stantially decreased. Meanwhile, new broad absorption
À1
bands appeared at 3415 and 1671 cm , which could be as-
signed to non-hydrogen-bonded NÀH and amide C=O ab-
sorption bands. We therefore conclude that hydrogen-bond-
ing is the primary driving force for the supramolecular self-
assembly of samples 1–4 below their Tm.
Samples 3 and 4 exhibited more complex phase behaviors.
For example, upon cooling, sample 3 showed a sharp T at
c
À1
1
(
018C (38.8 kJmol ) and
a
broad peak at 578C
15.6 kJmol ). Upon heating, two reverse processes took
place at 698C (21.3 kJmol ) and 1368C (40 kJmol ), re-
À1
The direction of hydrogen-bonding in the P(Tp) samples
2
À1
À1
was studied by polarized FTIR at room temperature. Repre-
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Chem. Asian J. 2010, 5, 1634 – 1641

Hydrogen Bonding Induced Supramolecular Self-Assembly
trum of sample 2 was a linear
addition of those of the organo-
soluble porphyrin and Tp
monoamine. Therefore, we con-
clude that the direct p–p inter-
atction between P and Tp was
not important for the self-as-
sembly of P(Tp)2 triad super-
molecules.
Hydrogen Bond-Assisted
Lamellar Structures in P(Tp)2
Supermolecules
To solve the crystalline struc-
tures for P(Tp)2 supermole-
cules, 2D XRD experiments
were performed on shear-ori-
ented samples and shear tem-
peratures were chosen to be
2
08C below the T . To make
m
sure that mechanical shear did
not change the phase structure
and phase transition, DSC was
used to double check the sam-
ples before and after shear. On
the basis of DSC results for
both sheared and unsheared
samples (see Figure S2 in the
Supporting Information), no
substantial effect was observed.
All the 2D XRD patterns in
Figure 5 can be explained by an
orthorhombic symmetry, and
the assigned Miller indices are
shown in Figure 6 A–D. The
unit cell dimensions are deter-
mined as:
2
Figure 4. Temperature-dependent FTIR spectra for P(Tp) triads (A) 1, (B) 2, (C) 3, and (D) 4, respectively.
2
Figure 5. Angle-dependent FTIR spectra for P(Tp) samples (A) 1 and (B) 3, respectively.
1
) a=7.16 nm, b=1.93 nm, and c=1.87 nm for sample 1;
sentative results for samples 1 and 3 are shown in Figure 5 A
and B, respectively. Samples were shear-oriented on KBr
2) a=9.30 nm, b=1.85 nm, and c=1.74 nm for sample 2;
3) a=5.02 nm, b=2.26 nm, and c=0.511 nm for sample 3;
4) a=9.13 nm, b=2.11 nm, and c=2.35 nm for sample 4.
plates at a temperature ca. 208C below the T using a spatu-
m
la. The 08-angle was defined as the polarization plane paral-
lel to the shear direction. Obviously, the amide I and the NÀ
The d-spacings of observed XRD reflections fit well to
those of calculated values, as demonstrated in Tables S1–S4
in the Supporting Information.
À1
H absorption bands at 1635 and 3326 cm were the stron-
gest when the angle was 08 and weakest when the angle was
9
08, suggesting that the hydrogen bonds were along the
Considering that the molecular weight of sample 1 was
2,247 gmol and the measured density was 1.120 gcm ,
À1
À3
shear direction. From the XRD analysis below, the shear di-
rection was along the stacking direction of the discotic Ps.
Therefore, we conclude that the hydrogen bonds were along
the stacking direction of the discotic P molecules.
To exclude the possibility of either J- or H-type of dimers
induced by direct p–p stacking between P and Tp, we per-
formed a UV/Vis study of sample 2, an organo-soluble por-
phyrin, and the corresponding Tp monoamine (see Figure S1
in the Supporting Information). Basically, the UV/Vis spec-
each unit cell should have eight P(Tp) supermolecules to
2
À3
match the theoretical density of 1.156 gcm . To determine
the exact molecular packing inside this orthorhombic unit
cell, one needed to perform single crystal XRD studies. Un-
fortunately, sufficiently large single crystals could not be ob-
tained, possibly as a result of too many alkyl chains in the
sample. Therefore, we propose a reasonable packing model
within the unit cell based on the molecular sizes as shown in
Chem. Asian J. 2010, 5, 1634 – 1641
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1637

J. Miao and L. Zhu
FULL PAPERS
1
0.8 nm). Therefore, the P(Tp) supermolecules should tilt
2
at an angle with respect to the a-axis (see Figure 7). Because
the spacer length (C6) was longer than the C5 alkyl chain
length in the Tp arms, the P and Tp disks were decoupled.
Two consequences resulted; (1) The tilt angles for P and Tp
might be different. (2) Neighboring P and Tp disks along
the c-axis might have different tilt angles with four mole-
cules forming a regular motif (see Figure 7). In this model,
the hydrogen bonds were along the c-axis, which was paral-
lel to the shear direction, consistent with the polarized
FTIR results discussed before.
This molecular packing scheme also applies for samples 2
and 4 because their unit cell dimensions are similar to that
for sample 1. Experimental densities for samples 2 and 4
À3
were 1.025 and 0.937 gcm , again suggesting eight supermo-
lecules per unit cell. Therefore, theoretical densities for sam-
À3
ples 2 and 4 are 1.041 and 0.963 gcm , respectively.
For sample 3, the observed a- and c-axes were only 5.02
and 0.511 nm, respectively, much smaller than those (a=
9
.3 nm and c=2.35 nm) for sample 4. Considering that the
spacer length C6 in sample 3 is shorter than the alkyl chain
length of C12 in the Tp arms, P and Tp are strongly coupled
together, and thus P disks do not tilt along the a-axis in
order to form regular p–p stacks (see Figure 8). Assuming
2
Figure 6. 2D XRD patterns for shear-oriented P(Tp) (A) sample 1 at
room temperature; (B) sample 2 1008C; (C) sample 3 at 1108C, and
(
D) sample 4 at room temperature.
[
64]
[65]
Figure 7; P–1.99 nm,
2
C5Tp–1.7 nm,
and C12Tp–
[66]
.5 nm. When we consider eight supermolecules in a unit
cell, the a-axis should accommodate two P(Tp) supermole-
2
cules. However, the a-axis (7.16 nm) was smaller than twice
the total planar length of the supermolecule (2ꢁ5.4=
Figure 8. Schematic representation of the packing model for P(Tp)
2
sample 3 with three orthogonal view angles (A-C), Only Tp is tilted
along the a-axis, and c-axis is thus 0.511 nm.
[66]
the C12Tp diameter is 2.5 nm, the tilt angle for the Tp is
calculated to be ca. 538. The measured density was
À3
0
.904 gcm , suggesting only one supermolecule per unit
À3
cell. The theoretical density was calculated to be 0.92 gcm ,
which is close to the observed one.
Figure 9 shows the 1D XRD profiles for samples 3 and 4
above and below the low temperature transitions. Obviously,
the low angle reflections remained the same before and
after the low temperature transitions for both samples, indi-
cating that C12 alkyl chain crystallization did not disrupt the
pre-existing crystalline structure. However, the amorphous
halos at high angles shifted to even higher q-values after
2
Figure 7. Schematic representation of the packing model for P(Tp) sam-
ples 1, 2 and 4 with three orthogonal view angles (A-C). Both P and Tp
are tilted with respect to the a-axis. Along the c-axis in (B), different
colors in P and Tp molecules represent different tilt angles and thus four
molecules form a repeat.
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Hydrogen Bonding Induced Supramolecular Self-Assembly
Scientific and used without further purification. Tp mono-amine was pre-
[
62]
pared according to the literature with slight modifications.
Instrumentation and Characterization
1
H NMR spectra were recorded on a Bruker spectrometer (500 MHz,
DMX 500). DSC experiments were carried out on a TA DSC-Q100 in-
strument. An indium standard was used for both temperature and enthal-
py calibrations. Approximately, 1–3 mg sample was used for the DSC
À1
study and the scanning rate was 108Cmin . SEC was performed on a
Viscotek GPCmax VE2001 with quadruple detectors. THF was used as
the solvent and polystyrene standards were used for calibration. PLM ex-
periments were performed using an Olympus BX51P microscope
equipped with an Instec HCS410 hot stage. FTIR was performed on a Ni-
clotet Magna 560 FTIR spectrometer.
Two-dimensional (2D) X-ray diffraction (XRD) experiments were per-
formed at the synchrotron X-ray beamline X27C at National Synchrotron
Light Source (NSLS), Brookhaven National Laboratory (BNL). The
wavelength of incident X-ray was 0.1371 nm. The scattering angle was
calibrated using silver behenate with the primary reflection peak at the
À1
scattering vector q=(4psinq)/l=1.076 nm , where q is the half-scatter-
ing angle and l is the wavelength. Fuji imaging plates were used as detec-
tors for XRD experiments, and digital images were obtained using a Fuji
BAS-2500 scanner. The typical data requisition time was 1 min. An
Instec HCS410 hot stage equipped with a liquid-nitrogen cooling accesso-
ry was used for temperature-dependant X-ray experiments. One-dimen-
sional (1D) XRD curves were obtained by integration of the correspond-
ing 2D XRD patterns.
Figure 9. Temperature-dependent 1D XRD profiles for samples 3 and 4,
respectively.
cooling below the low temperature transitions, suggesting a
decrease in the average distance among alkyl chains induced
[
64,67]
General Synthesis Procedure and Characterization for Samples 1–4
[64]
by the C12 crystallization.
A
solution of methyl-4-formylbenzoate (3 g, 18.4 mmol) in pyrrole
(
17.4 mL, 250 mmol) was degassed by bubbling dry N for 2 h. After
2
adding 0.11 mL of TFA (1.4 mmol) to the degassed solution, it was
stirred at room temperature in the dark for 4 h. The reaction mixture was
diluted with 200 mL of CHCl and washed with 0.1m aqueous NaOH so-
3
Conclusions
lution and double distilled water successively. The organic layer was
dried over anhydrous Na SO , and the solvent and the excess of pyrrole
In summary, we have successfully synthesized a series of
2
4
doubly discotic P(Tp) triad supermolecules with amide link-
were removed under a reduced pressure to afford a viscous brown oil
which solidified after 12 h. The dry solid was dissolved in a minimum
2
ages. Hydrogen bonding along the P stacks was responsible
for the supramolecular self-assembly. Besides hydrogen
bonding, the coupling between P and Tp disks was also an
important factor for the supramolecular self-assembly of
amount of CHCl
3 2
and loaded on top of a SiO column and eluted by
pure CHCl . The first brown fraction, which was unreacted pyrrole, was
3
recovered. The later pale yellow fraction was collected and the solvent
was removed using a rotary evaporator at room temperature. The result-
ing pale grey solid was washed with 50 mL of cold ethyl acetate and final-
P(Tp) supermolecules. For samples 1, 2, and 4, the spacer
2
1
ly 4.9 g product was obtained (45% yield). H NMR (500 MHz, CDCl
3
):
lengths were longer than or similar to the alkyl chain lengths
in the Tp arms, and thus P and Tp were decoupled to a
large degree. This decoupling resulted in non-uniform tilt
angles for P and Tp disks along both the a- and c-axes.
3
d=3.90 (s, 3H, COOCH ), 5.51 (s, 1H, F-CH), 5.92 (m, 2H, NH), 6.20
(
d, 2H, pyrrole C-CH), 6.75 (d, 2H, NH-CH), 7.25 (t, 2H, NH-CH-CH),
and 8.0 ppm (d, 4H, F-H).
A solution of dipyrrole (3 g, 10.7 mmol) and benzaldehyde (1.13 g,
Therefore, large unit cells with eight P(Tp) supermolecules
10.7 mmol) in 400 mL of CHCl
Following the addition of BF ·Et
3
was degassed by bubbling N
O (1.37 mL, 10.7 mmol) to the degassed
2
for 2 h.
2
3
2
per cell were observed. For the sample 3, the spacer was
much shorter than the C12 alkyl arms in the Tp arms, and P
and Tp were strongly coupled. Therefore, both P and Tp
had uniform tilt angles along both the a- and c-axes. A small
solution, the reaction mixture was stirred at room temperature in the
dark for 2 h. Subsequently, p-chloranil (4.5 g, 19 mmol) was added to the
resulting dark red solution. After stirring overnight, 5 mL of triethyla-
mine (38 mmol) was added to the reaction mixture to neutralize the
Lewis acid. The crude reaction mixture was then concentrated and
unit cell with only one P(Tp) supermolecule per cell was
2
loaded on a SiO
purple solution was evaporated to afford a mixture of porphyrins which
was further subject to column chromatography (SiO , hexanes/toluene=
:1 to 1:3). The desired para-substituted porphyrin dicarboxylates were
2 3
flash column using CHCl as the eluent. The obtained
obtained.
2
2
obtained right before the ortho-substituted isomers. After removing the
ortho-substituted isomer, the desired para-substituted porphyrin dicar-
boxylate was obtained as a later fraction. After evaporating the solvent,
Experimental Section
1
Materials
a purple solid was obtained (0.6 g, 10% yield). H NMR (500 MHz,
3 3
CDCl ): d=4.12 (s, 6H, COOCH ), 7.81 (m, 6H, 3,4,5-F-H in non-ester
Methyl-4-formylbenzoate was purchased from TCI America, Inc. Benzo-
functionalized phenyl rings), 8.25 (m, 4H, 2,6-F-H in non-ester function-
alized phenyl rings), 8.33 (m, 4H, 2,6-F-H in ester functionalized phenyl
ring), 8.49 (m, 4H, 3,5-F-H in ester functionalized phenyl ring), 8.79 (m,
triazol-1-yl-oxytripyrrolidinophosphonium
PyBOP) and N,N-diisopropylethylamine (NPr
hexafluorophosphate
Et) were purchased from
(
2
Aldrich. Pyrrole, benzaldehyde, boron trifluoride etherate (BF
3 2
·Et O), p-
chloranil, trifluoroacetic acid (TFA), and all solvents were from Fisher
Chem. Asian J. 2010, 5, 1634 – 1641
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1639

J. Miao and L. Zhu
FULL PAPERS
4
4
H, P-H close to non-ester functionalized phenyl ring), and 8.90 ppm (m,
H, P-H close to ester functionalized phenyl ring).
Acknowledgements
The para-substituted porphyrin dicarboxylate (0.6 g, 1.05 mmol) was dis-
solved in 200 mL of tetrahydrofuran (THF)/methanol (1:1 vol/vol) mix-
ture, and KOH (3 g) in 30 mL of H O was added to carry out the hydrol-
2
This work was supported by NSF CAREER Award DMR-0348724,
DuPont Young Professor Grant, and 3M Nontenured Faculty Award.
The synchrotron X-ray experiments were carried out at the National Syn-
chrotron Light Source, Brookhaven National Laboratory, which is sup-
ported by the U.S. Department of Energy. Assistance from Drs. Lixia
Rong and Jie Zhu, and Prof. Benjamin Hsiao at State University of New
York at Stony Brook for synchrotron X-ray experiments is highly ac-
knowledged.
ysis reaction under reflux for 12 h. After cooling to ambient temperature,
the organic solvent was removed under a reduced pressure, and the resi-
due was diluted with 100 mL of water. The resulting dipotassium salt of
the corresponding porphyrin dicarboxylic acid was collected by filtration.
The solid dipotassium salt was acidified with concentrated HCl, followed
by a thorough wash with hot water. Finally, a purple powder of the por-
1
phyrin dicarboxylic acid (570 mg, 96% yield) was obtained. H NMR
(
6
500 MHz, [D ]DMSO): d=7.03 (brm, 6H, 3,4,5-F-H in non-ester func-
tionalized phenyl ring), 7.26 (brs, 4H, 2,6-F-H in non-ester functional-
ized phenyl ring), 7.52 (m, 4H, 2,6-F-H in ester functionalized phenyl
ring), 7.64 (m, 4H, 3,5-F-H in ester functionalized phenyl ring), 8.05
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(
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structures in Scheme 1) of the corresponding triphenylene mono-amine.
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3
0 min. The completion of reaction was checked by thin layer chromatog-
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3
4
moval of the solvent under vacuum, crude products were purified by
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1
H NMR for 1, (CDCl
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C NMR for 1, (CDCl ): d=14.1, 22.6, 28.4, 29.1, 40.3, 69.6, 107.3, 118.9,
1
1
20.5, 123.6, 125.3, 126.7, 127.8, 134.5, 134.7, 141.9, 145.3, 149.0,
67.7 ppm.
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C NMR for 2, (CDCl ): d=14.1, 22.6, 28.4, 29.1, 40.3, 69.6, 107.3, 118.9,
3
20.5, 123.6, 125.3, 126.7, 127.8, 134.5, 134.7, 141.9, 145.3, 149.0,
67.7 ppm.
3
): d=1.0–0.85 (30H, m, CH
3
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CH
2
2
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H NMR of 4, (CDCl
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.4–8.1 (12H, m, P phenyl F-H), 9.0–8.8 ppm (8H, m, P pyrrole P-H).
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Received: January 8, 2010
Published online: May 21, 2010
Chem. Asian J. 2010, 5, 1634 – 1641
ꢀ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1641