Aggregation of asphaltene model compounds using a porphyrin tethered to a carboxylic acid

Article abstract of DOI:10.1039/c5ob00836k

A Ni(ii) porphyrin functionalized with an alkyl carboxylic acid (3) has been synthesized to model the chemical behavior of the heaviest portion of petroleum, the asphaltenes. Specifically, porphyrin 3 is used in spectroscopic studies to probe aggregation with a second asphaltene model compound containing basic nitrogen (4), designed to mimic asphaltene behavior. NMR spectroscopy documents self-association of the porphyrin and aggregation with the second model compound in solution, and a Job's plot suggests a 1:2 stoichiometry for compounds 3 and 4. This journal is

Full text of DOI:10.1039/c5ob00836k

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ARTICLE TYPE
Aggregation of asphaltene model compounds using a porphyrin tethered
to a carboxylic acid
a
a
b
a*
Matthias Schulze, Marc P. Lechner, Jeffrey M. Stryker, and Rik R. Tykwinski
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
A Ni(II) porphyrin functionalized with an alkyl carboxylic
acid (3) has been synthesized to model the chemical behavior
from the cumulative effect of numerous intermolecular stabilizing
forces, which might include, among others, π-π-stacking, axial
of the heaviest portion of petroleum, the asphaltenes. 50 coordination of metalloporphyrins, hydrogen bonding,
8
hydrophobic interactions, and acid-base interactions.
Specifically, porphyrin 3 is used in spectroscopic studies to
probe aggregation with a second asphaltene model compound
containing basic nitrogen (4), designed to mimic asphaltene
behavior. NMR spectroscopy documents self-association of
the porphyrin and aggregation with the second model
compound in solution, and a Job’s plot suggests a 1:2
stoichiometry for compounds 3 and 4.
1
0
1
5
Introduction
The foreseeable exhaustion of conventional fossil fuels has
resulted in an increasing focus on efficient use of alternative
1
petroleum sources, such as heavy crude oil. In order to convert
2
2
3
3
4
4
0
5
0
5
0
5
heavy oil to valuable fuels, however, significant upgrading is
2
required, and these processes are hampered by the heaviest and
3
most problematic component of heavy oil, the asphaltenes.
Asphaltenes are commonly known to cause problems for a
variety of practical processes, such as transportation, storage, and
2
-4
refining. To solve these issues, significant efforts have been
2, 4, 5
expended to understand the bulk behavior of asphaltenes,
and
Fig. 1 Schematic example of an a) island asphaltene compound (MW
these efforts have even suggested that the carbon-rich and 55 = 756 g/mol) from reference 13 and b) archipelago asphaltene
compound (MW = 754 g/mol) from reference 8. Examples of model
heteroatom doped composition of asphaltenes might yield
6
,
7
compounds used to study aggregation of asphaltenes, representing c)
14 15
island (MW = 1280 g/mol) and d) archipelago (MW = 613 g/mol)
structures.
materials for electronic devices.
In spite of these studies,
however, the general molecular structure of the asphaltenes
8
remains to be resolved, and a major barrier to the goal is the
formation of very stable aggregates between individual molecules 60 Much of the support for the island model comes from a “top-
9
that complicates many analysis techniques.
down” approach, i.e., the study of natural asphaltene samples by
1
3
For almost a century, it has been suggested and, for the most part,
accepted that asphaltenes are composed of large aromatic cores
that also contain heteroaromatics and metalloporphyrins, with a
molecular weight (MW) of ca. 750 g/mol (Fig. 1a). These large 65 experiments,
various physical and analytical methods. Evidence for the
archipelago model using the “top-down” approach has also been
reported, including ruthenium-ion-catalyzed oxidation (RICO)
1
6-18
19,
20
small-angle
neutron
scattering,
2
1, 22
23, 24
aromatic islands are then surrounded by functional groups,
calculations,
and thermal cracking experiments.
We
10-12
including alkyl groups and alkyl carboxylic acids.
This
hypothesize that “a bottom-up” approach, is paramount to
understanding asphaltene aggregation on a molecular level. While
the “top-down” approach looks at properties of the bulk material,
paradigm gives rise to the “continental” or “island” model (more
specifically the Yen-Mullins model), and it is believed that
aggregation in these types of molecules is driven primarily by π-π
70
a
“bottom-up” study targets specific molecules with
1
3
25
stacking interactions.
functionalities found in asphaltenes (Figs. 1c–d). With the exact
structure of the molecules known, physical properties can be
Alternatively, an archipelago model for the asphaltenes has been
introduced, in which smaller aromatic islands are tethered
investigated at a molecular level. This tactic is quite common in
8
26-28
together by alkyl chains (Fig. 1b). In the case of archipelago
supramolecular materials chemistry,
for example, and should
asphaltenes, it has been hypothesized that aggregation results 75 be useful toward deciphering specific intermolecular interactions
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Page 2 of 7
related to the asphaltene aggregation, regardless of whether the 55 (Fig. 2), in which the pyridyl-ring is combined with large
continental or the archipelago motif is being considered. There
are, however, surprisingly only a few efforts reported in the
literature that describe the rational synthesis of compounds
aromatic groups appended via flexible alkyl tethers. Binding
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studies by NMR spectroscopy show self-association of porphyrin
DOI: 10.1039/C5OB00836K
3 and the formation of an aggregate between 3 and 4 in solution,
1
5, 29-31
5
0
5
0
5
0
5
0
5
0
specifically to mimic the behavior of asphaltenes.
Rather,
demonstrating the potential of this aggregation motif for native
existing molecules are often employed, presumably out of 60 asphaltenes.
convenience, to emulate asphaltene molecules. For example,
hexabenzocoronenes (HBCs) substituted with alkyl chains (1)
have been used in studies by Gray and Müllen to represent
molecules of the continental model, and such HBCs show dimer
1
1
2
2
3
3
4
4
5
8
, 14, 32
formation in organic solvents (Fig. 1c),
while Anisimov
examined the aggregation behavior of a tert-butyl substituted
3
3
HBC. HBCs, however, have an aromatic core built from 13
fused rings, and the majority of asphaltene molecules are
3
4, 35
expected to have only 4 to 10 fused rings.
Akbarzadeh et al.
have used smaller ring systems (alkyl bridged pyrene model
2
9
compounds) either with or without heteroatoms, and only
structures with heteroatoms form dimers in organic solvents. In
line with these results, Tan et al. have described that the 2,2’-
bipyridine derivative 2 forms dimers both in solution and in the
Fig. 2 Model compounds under study to probe aggregation based on the
interactions of an acid (3) and base (4).
1
5
49
solid state (Fig. 1d), and it is suggested that water enhances
dimer formation, presumably by the formation of hydrogen
bonding, bridging the heteroatoms between two individual
Results and discussion
3
0
molecules. Experimental results were also supported by density
65
Synthesis
3
6, 37
functional theory and 3D-RISM-KH calculations.
Studies to date with model asphaltene compounds, as briefly
summarized in the preceding paragraphs, are not fully consistent
with the view that asphaltene aggregation is dominated by π-
stacking. Given the acknowledged structural diversity of the
Aldehyde 5 (Scheme 1) was synthesized from 1-bromo-2-
(methoxymethyl)benzene as described by Ullenius and
5
0
coworkers.
butylbenzaldehyde (6), and pyrrole were used in a mixed
⋅OEt as a Lewis-acid and EtOH
as a co-catalyst, followed by oxidation with DDQ, according to
Subsequently, aldehyde 5, commercial 4-n-
asphaltenes, it seems likely that intermolecular associations might 70 porphyrin condensation with BF
3
2
be better described by multiple cooperative interactions
8
51
52
facilitated by heteroatoms and functional groups. An obvious
procedures reported by Lindsey and Jux. From this reaction,
target under this premise is the interaction of an acid and a base,
as expected in natural asphaltenes, for example, between pyridyl-
the unsymmetrical methoxymethyl substituted porphyrin 7a and
5
3
the symmetrical derivative 8 were isolated in significant yields.
1
2, 38
and carboxylic acid groups.
To explore this concept, in the 75 The desired target, porphyrin 7a, was then reacted with HBr in
5
2
current study two model compounds have been chosen, an acid
and a base (Fig. 2). A porphyrin group has been chosen as a
platform for the acid moiety, namely compound 3. Porphyrins are
known to exist in petroleum since the pioneering work by Treibs
AcOH, according to a procedure by Jux, to give bromide 7b,
which was used without further purification. The route of Jasinski
5
4
et al. for cyanation of bromomethyl TPPs was modified slightly,
and treatment of the crude bromide 7b with KCN in PEG 400
3
9-42
in 1934,
and these so-called petroporphyrins are mainly 80 gave the cyanomethyl substituted porphyrin 9 in excellent yield.
1
2, 43
observed as V(IV)O and Ni(II) species.
To the best of our
Hydrolysis of the nitrile 9 under acidic conditions yielded the
carboxylic acid, and the free base porphyrin 10 was isolated in
good yield via column chromatography. Conversion of 10 to the
knowledge, however, only simple, unfunctionalized, and
commercially available porphyrins have been employed to model
4
4
asphaltene aggregation. Archipelago-type porphyrins have been
Ni(II) porphyrin 3 was first attempted out using Ni(acac)
2
in
4
5
used for the investigation of thermal cracking behavior, but 85 toluene. Although quantitative metallation was achieved,
there are no studies that report a synthetic strategy specifically
designed for porphyrins that enable the study of asphaltene
purification was difficult due to presence of Ni(acac)
to an isolated yield for 3 of only 31%. Changing the metallation
conditions from Ni(acac) in toluene to Ni(OAc) ⋅4H O in
MeOH/CHCl , however, afforded the desired porphyrin 3 in 95%
model compounds for petroporphyrins, albeit without a focus on 90 yield. Archipelago model compound 4 was synthesized via
2
, which led
2
6
aggregation.
It is worth noting the extensive synthetic
2
2
2
porphyrins independently reported by Clezy and Lash to serve as
3
4
6-48
aggregation.
Sonogashira
reaction
of
1-ethynylpyrene
with
2,6-
To explore the aggregation behavior of porphyrin 3, it is
combined with a second compound that features a basic nitrogen
group. Namely, we have chosen archipelago model compound 4
dibromopyrdine and subsequent hydrogenation, as detailed
5
5
previously (see SI for details).
2
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ARTICLE TYPE
Scheme 1 Synthesis of the Ni(II) porphyrin 3 featuring an alkyl carboxylic acid group.
explained by a combination of steric and electronic effects, as
described in detail by Kitao and Jarboe for simple pyridine
Aggregation in solution
35
5
7
Before exploring aggregation of porphyrin 3 with archipelago
model compound 4, a series of control experiments were done.
First, phenylacetic acid was used as a simple carboxylic acid in a
derivatives.
5
0
5
0
5
0
Turning attention to the porphyrin carboxylic acid 3, dilution
1
titrations were first investigated by H NMR spectroscopy to
NMR titration experiment with pyridine in benzene-d
6
at 24 ± 2
determine self-association. It was clear from these titrations that
°
C (while toluene is more commonly used for aggregation 40 porphyrin 3 forms a dimeric species in benzene-d , and chemical
6
studies, the symmetrical structure of benzene allows more facile
shift analysis and fitting from multiple signals gave a
1
–1
1
1
2
2
3
analysis of H NMR spectra due to the reduced number of signals
dimerization constant of K = 390 ± 27 M (see SI).
dim
1
from the solvent). Specifically, addition of pyridine (1 to 8
Finally, a H NMR titration experiment was done with porphyrin
equivalents) to a 2.5 mM solution of phenylacetic acid gave
3 by addition of pyridine (1 to 8 equivalents). Fitting of the
1
changes in the H NMR chemical shift for the signal of the 45 chemical shifts from multiple signals and considering K = 390
dim
–
1
–1
methylene protons of phenylacetic acid (see SI). Nonlinear curve
fitting for the chemical shift data with a 1:1 binding model gave
± 27 M for 3, Kassoc = 178 ± 18 M was determined (see SI),
which was comparable to the binding experiment between
phenylacetic acid and pyridine (vide supra).
–
1
an association constant Kassoc= 123 ± 12 M .
In a second experiment, phenylacetic acid was titrated with model
The interactions between model compounds 3 and 4 were then
5
6
compound 4, rather than pyridine. At first, a 2.5 mM solution of 50 explored, using an analogous set of conditions for both the
1
phenylacetic acid was used for the titration with 4. Limited by the
solubility of 4, only up to 4 equivalents could be added. As only
weak binding was observed, a second titration with a 1.25 mM
solution of phenylacetic acid was performed allowing addition up
titration and H NMR chemical shift analysis. Namely, the
concentration of porphyrin 3 was kept constant at 2.5 mM, and
the concentration of model compound 4 was varied from a
minimum of 1.25 mM to a maximum of 10 mM (this was the
to 8 equivalents of 4. Both titrations gave concentration 55 solubility limit of 4). The signals of the two methylene groups of
dependent changes for the chemical shift for the signal of the
methylene protons of phenylacetic acid, but the binding was quite
b c c b
4 (H and H , see Fig. 2) shifted upfield from 3.86/3.34 (H /H ) to
3.78/3.29 (H /H ) ppm upon addition of 0.5 equivalents 4 to the
c
b
–
1
lower compared to pyridine, with an averaged Kassoc = 24 ± 8 M
see SI), obtained from the two titrations detailed above. In
porphyrin solution (Fig. 3), whereas further addition of 4 resulted
(
in less significant downfield shifts. The signal of the methylene
general, it is know that substitution in the 2,6-positions of the 60 group protons of 3 (H , see Fig. 2) shifted downfield upon
a
pyridyl-ring has an impact on basicity, e.g., for pyridine, 2,6-
lutidine, and 2,6-diisopropylpyridine, pK = 4.38, 5.77, and 5.34,
respectively. Likewise, substitution also causes steric repulsion
addition of 4, from 3.20 ppm to a maximum of 3.43 ppm, after
addition of four equivalents of 4.
a
5
7
5
7
inhibiting hydrogen bonding. Thus, the observed decrease in
assoc going from pyridine to model compound 4 is likely
K
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similar to that of 4. It has also been shown that dimerization of 2
is enhanced by the addition of water, which had the effect of
View Artic 3l e0 Online
DOI: 10.1039/C5OB00836K
35
forming an intermolecular bridge between bipyridyl groups. It
is, thus, reasonable that the carboxylic acid functionality of
porphyrin 3 might mediate similar interactions between 4, by
bridging between two pyridyl-units, as in the role of water for the
dimerization of 2. The suggested stoichiometry from the Job’s
plot must be interpreted with caution, however, due to the self-
association of porphyrin 3. Thus, it is not possible at this point to
unambiguously declare the nature of the interaction between 3
and 4.
40
Conclusions
45
We have synthesized a new metalloporphyrin bearing an alkyl
carboxylic acid (3), and specific aspects of asphaltene
aggregation have been studied using this porphyrin. NMR
spectroscopic analyses document the self-dimerization of the
1
Fig. 3 H NMR titration of 3 (2.5 mM constant) with increasing amounts
of 4 in benzene-d ; a) 3 (2.5 mM); b) 4 (1.25 mM); c) 3:4 = 2:1; d) 3:4 =
:1; e) 3:4 = 1:1.5; f) 3:4 = 1:2; g) 3:4 = 1:2.5; h) 3:4 = 1:3; i) 3:4 = 1:3.5;
j) 3:4 = 1:4; * = signal of the methylene group protons H of 3; see Fig. 2
a
for proton assignment.
6
porphyrin carboxylic acid 3 in benzene-d , as well as aggregation
6
1
50
of 3 with an asphaltene model compound that bears a basic
5
pyridine group (i.e., archipelago 4). A Job’s plot analysis between
3
and 4 suggests a 1:2 complex, but the exact nature of the
The observed relationship between chemical shift and
concentration is consistent with expected acid-base interactions
association cannot be categorically established, due mainly to the
self-association (self-dimerization) of porphyrin acid 3.
between the carboxylic acid functionality of 3 and the basic 55 While the stoichiometry of the 3/4 complex remains unresolved,
1
0
nitrogen of 4. The chemical shifts for multiple signals upon
titration of 3 with 4 were fit to a 1:1 binding model, suggesting a
this study does clearly show that the interactions between 3 and 4
are stronger than those of the individual model compound with
either a simple base or acid, respectively. That is to say that the
–
1
K
assoc = 316 ± 32 M (Fig. 4). The 1:1 binding model is also
supported by the presence of a weak signal for a 1:1 complex
between 3 and 4 in the high resolution APPI mass spectrum (see 60 phenylacetic acid (24 ± 8 M ) are weaker than for 3 and 4
–
1
K
assoc determined for 3 with pyridine (178 ± 18 M ) and 4 with
–
1
1
5
SI).
together, regardless of whether a 1:1 or 1:2 complex is formed.
Based on our results, we hypothesize that the enhanced
aggregation observed for 3 and 4 originates from the presence of
additional intermolecular forces beyond the expected acid-base
interactions (e.g., π-stacking, hydrogen bonding), as suggested in
65
8
the archipelago model. Further analysis by both experiment and
theoretical calculations are underway.
Experimental Section
General
70
All chemicals and solvents were used as received from
commercial suppliers. 1-Ethynylpyrene was prepared according
Fig. 4 Concentration dependent chemical shifts for the signal of the
methylene group protons of porphyrin 3 upon titration with 4 and fitting
to a 1:1 binding model.
61
to literature. For the aldehyde synthesis, dry THF was distilled
from sodium/benzophenone and DMF “with molecular sieve”
(water <50 ppm) from Acros Organics was used. Solvent ratios
2
2
3
0
5
0
To further investigate the nature of the complex formed between
3
and 4 in solution, Job’s method of continuous variation was 75 are given as volume:volume. NMR spectra were recorded on a
5
8, 59
1
used.
Interestingly, the maximum is observed in the Job’s
Bruker Avance 300 operating at 300 MHz ( H NMR) and 75
1
3
plot at a mole fraction of 0.3 for 3, suggesting a 1:2 complex
between the porphyrin acid and model compound 4,
respectively. Nonlinear curve fitting, considering both binding
MHz ( C NMR), or a Bruker Avance 400 operating at 400 MHz
1
13
3
( H NMR) and 100 MHz ( C NMR), or a Jeol GX 400 operating
1
3
at 100 MHz ( C NMR) at rt, if not otherwise specified. Signals
events, namely self-association of 3 (Kdim = 390 ± 27 M ) and a 80 were referenced to residual solvent peaks (δ in parts per million
–
1
1
13
1
1
:2 binding model, results in an overall association constant of
(ppm) H: CDCl
3 6 6 3
, 7.26 ppm; C D , 7.16 ppm; C: CDCl , 77.0
6
–2 60
.23 ± 0.1 × 10 M .
ppm; C , 128.0 ppm). Coupling constants were assigned as
6 6
D
The formation of a 1:2 complex between model compounds 3
observed. Mass spectra were recorded from Bruker micro TOF II
(ESI) and Bruker maxis 4G (APPI) instruments. IR spectra were
and 4 would be in line with the results of Tan et al., who report
formation of a dimer for the ethano-linked pyrene substituted 85 recorded on a Varian 660-IR spectrometer. UV-vis spectra were
1
5
2
,2’-bipyridine derivative 2 (in CDCl
3
), which shares a structure
recorded on a Varian Cary 5000 UV-vis spectrophotometer (λ in
4
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Organic & Biomolecular Chemistry
−
1
−1
13
nm; ε in M cm ). TLC analysis was carried out with TLC plates
J = 7.3 Hz, 1.4 Hz, 1H), 4.78 (s, 2H), 3.39 (s, 3H); C (75 MHz,
®
from Macherey-Nagel (ALUGRAM
visualized by UV-light of 254 nm or 366 nm. Silica Gel 60 M
0.04–0.063 mm) for column chromatography was purchased
SIL G/UV254
)
and 60 CDCl ) δ 192.4, 140.5, 133.5, 133.0, 132.0, 127.7, 127.4, 71.5,
3
V +i ew Article Online
58.2. ESI HRMS m/z calcd. for C H O ([M + H] ) 151.0754,
9 11 2
DOI: 10.1039/C5OB00836K
(
found 151.0753.
5
0
5
0
5
0
5
0
5
0
5
from Macherey-Nagel.
Porphyrin 7a. In degassed CH
2
Cl
2
(1.5 L), 4-n-
Compound 4. 1-Ethynylpyrene (0.491 g, 2.17 mmol) was
butylbenzaldehyde (90% pure, 2.1 mL, 11 mmol), pyrrole (1.0 g,
added to a deoxygenated solution of 2,6-dibromopyridine (0.222 65 1.0 mL, 15 mmol), and aldehyde 5 (0.563 g, 3.75 mmol) were
g, 0.937 mmol) in THF (70 mL) and diisopropylamine (10 mL). dissolved under a N -atmosphere. After addition of EtOH
PdCl (PPh (0.127 g, 0.181 mmol) and CuI (0.052 g, 0.27 (1.5 mL) and BF ·OEt (0.24 g, 0.21 mL, 1.7 mmol), the solution
mmol) were sequentially added and the solution stirred at reflux
for 16 h under a N -atmosphere. The solvents were removed in
2
2
3
)
2
3
2
1
1
2
2
3
3
4
4
5
5
was stirred for 1 h at rt. DDQ (3.41 g, 15.0 mmol) was added and
the mixture stirred for 2 h at rt. The solution was concentrated by
2
vacuo, and the resulting solid was washed with MeOH (5 x 20 70 rotary evaporation and the residue filtered through a plug of silica
mL), H O (5 x 20 mL), MeOH (2 x 20 mL), hexanes (50 mL), gel (CH Cl ). The black/purple solid obtained after removal of
the solvent was purified by column chromatography (silica gel,
hexanes/CH Cl 1:1) to afford the porphyrin 8 (0.430 g, 18%) as
the first fraction and the porphyrin 7a (0.445 g, 14%) as the
times), and stirred at rt for 3 d. The heterogeneous mixture was 75 second fraction as purple solids. Mp 226–228 °C. R = 0.59
filtered over Celite and the solvent removed. Purification by (hexanes/CH Cl 1:1). UV-vis (CH Cl ) λmax (ε) 419 (569000),
column chromatography (silica gel, CHCl /hexanes 4:1) afforded
compound 4 as a yellow solid (0.366 g, 73%). Mp 186–187 °C. R
0.18 (CHCl /hexanes 4:1). IR (ATR) 3037 (w), 2924 (w), 1708
w), 1579 (m), 1453 (m) cm ; H NMR (300 MHz, CDCl
2
2
2
and dried in vacuo. The crude product, toluene (300 mL), and
Pd/C (10%, 0.050 g) were added to a flask. The flask was fitted
2
2
2 2
with a balloon filled with H (ca. 15 psi), purged with H (3
f
2
2
2
2
3
516 (21000), 550 (9830), 590 (6480), 646 (5150) nm; IR (ATR)
–
f
3314 (w), 2951 (m), 2923 (m), 2858 (m), 1465 (m), 1346 (m) cm
1
1
=
3
3
; H NMR (300 MHz, CDCl ) δ 8.92–8.89 (m, 6H), 8.73 (d,
–
1
1
(
3
) δ 80 J = 4.8 Hz, 2H), 8.20–8.09 (m, 7H), 7.97 (d, J = 7.2 Hz, 1H), 7.85
(td, J = 7.6 Hz, J = 1.2 Hz, 1H), 7.66 (td, J = 7.5 Hz, J = 1.2 Hz,
1H), 7.60–7.57 (m, 6H), 4.15 (s, 2H), 2.99 (t, J = 7.7 Hz, 6H),
2.89 (s, 3H), 1.94 (pent, J = 7.6 Hz, 6H), 1.62 (sext, J = 7.4 Hz,
8
1
.35 (d, J = 9.3 Hz, 2H), 8.14 (d, J = 7.6 Hz, 4H), 8.11–7.94 (m,
0H), 7.83 (d, J = 7.8 Hz, 2H), 7.32 (t, J = 7.7 Hz, 1H), 6.80 (d, J
1
= 7.7 Hz, 2H), 3.88–3.83 (m, 4H), 3.48–3.43 (m, 4H); H NMR
400 MHz, C ) δ 8.38 (d, J = 9.2 Hz, 2H), 7.97–7.90 (m, 8H),
.85–7.73 (m, 8H), 6.89 (t, J = 7.6 Hz, 1H), 6.51 (d, J = 7.6 Hz, 85 (75 MHz, CDCl
13
(
6
D
6
6H), 1.13 (t, J = 7.3 Hz, 9H), –2.66 (br s, 2H); C NMR
) δ 142.3, 140.19, 140.17, 139.5, 139.3, 134.6,
7
2
3
1
3
H), 3.87–3.83 (m, 4H), 3.36–3.32 (m, 4H); C NMR (75 MHz,
) δ 160.4, 135.7, 131.4, 130.9, 129.9, 128.7, 127.5, 127.34,
127.31, 126.6, 125.8, 125.01, 124.97, 124.9, 124.8, 124.7, 123.4,
134.0, 131.1 (br), 130.7 (br), 128.6, 126.73, 126.69, 126.3, 125.5,
120.6, 120.3, 116.9, 72.7, 58.1, 35.7, 33.8, 22.6, 14.2 (12 signals
CDCl
3
coincident or not observed). APPI HRMS m/z calcd. for
1
3
+
1
20.8, 39.8, 33.6 (one signal coincident or not observed);
NMR (100 MHz, C ) δ 161.1, 136.6, 136.3, 132.0, 131.5,
30.5, 129.3, 128.6, 127.0, 126.0, 125.8, 125.7, 125.2, 125.1,
23.9, 120.5, 40.7, 33.9 (three signals coincident or not
C
C
58
H
59
N
4
O ([M + H] ) 827.4683, found 827.4713.
5
3
6
D
6
90
Porphyrin 8. Mp >300 °C. R
f 2 2
= 0.85 (hexanes/CH Cl 1:1).
1
IR (ATR) 3314 (w), 3020 (vw), 2951 (w), 2923 (m), 2854 (m),
–
1 1
1
3
1466 (w), 1347 (w) cm ; H NMR (300 MHz, CDCl ) δ 8.89 (s,
1
3
1
observed);
C
–
H
HSQC (400 MHz,
C
6
D
6
,
selected
8H), 8.14 (d, J = 8.0 Hz, 8H), 7.57 (d, J = 8.0 Hz, 8H), 2.97 (t,
correlations) δ 136.3 ↔ 6.89; 120.5 ↔ 6.51; 40.7 ↔ 3.36–3.32;
J = 7.7 Hz, 8H), 1.98–1.88 (m, 8H), 1.61 (sext, J = 7.4 Hz, 8H),
1
3
1
13
3
3.9 ↔ 3.87–3.83; C – H HMBC (400 MHz, C
correlations) δ 161.1 ↔ 6.89, 6.51, 3.87–3.83, 3.36–3.32; 136.6
8.38, 7.97–7.90, 3.87–3.83, 3.36–3.32; 120.5 ↔ 6.51, 3.36–
3.32; 40.7 ↔ 6.51, 3.87–3.83; 33.9 ↔ 3.36–3.32. APPI HRMS
6 6
D , selected 95 1.12 (t, J = 7.3 Hz, 12H), –2.71 (s, 2H); C NMR (100 MHz,
CDCl
3
) δ 142.3, 139.5, 134.6, 130.9 (br), 126.7, 120.1, 35.7,
↔
33.8, 22.6, 14.1 (1 signal coincident or not observed). ESI HRMS
+
m/z calcd. for C60
Porphyrin 9. To a solution of 7a (58 mg, 0.070 mmol) in
Cl (15 mL), was added HBr in glacial HOAc (33%, 4.0 g,
63 4
H N ([M + H] ) 839.5047, found 839.5053.
+
m/z calcd. for C41
-Methoxymethyl
methoxymethyl)benzene (1.50 g, 7.46 mmol) was dissolved in
dry THF (75 mL) under a N -atmosphere. After cooling to –
H30N ([M + H] ) 536.2373, found 536.2374.
5
0
2
benzaldehyde
(5).
1-Bromo-2- 100 CH
2
2
(
8.5 mL, 49 mmol). The resulting dark green solution was stirred
at rt. After 4 h, an additional amount of HBr in glacial HOAc
(33%, 0.94 g, 2.0 mL, 12 mmol) was added and the mixture
2
78 °C, n-BuLi (2.5 M in hexane, 3.6 mL, 9.0 mmol) was slowly
added. After stirring for 1 h, DMF was added (0.82 g, 0.86 mL,
2 2 2
stirred at rt for 2 h. H O (50 mL) and CH Cl (50 mL) were
1
2
1 mmol), and the mixture was allowed to warm to rt while 105 added. The organic layer was separated, washed with H O
stirring over night for 16 h. The solution was poured into a
(100 mL), an aqueous saturated solution of NaHCO
and H O (100 mL). The organic phase was dried over MgSO
filtered. The solvent was removed and the crude product 7b
(R = 0.67 (hexanes/CH Cl 1:1)) dried in vacuo and used without
2
and 110 further purification. In PEG 400 (12 mL), the crude product 7b
3
(100 mL),
mixture of brine and HCl (150 mL, 1:1) and extracted with Et
(2 × 75 mL). The combined organic layers were washed with
O (3 × 150 mL) and dried over MgSO . After filtration and
removal of the solvent, the residue was dissolved in CH Cl
2
O
2
4
and
H
2
4
f
2
2
2
filtered through a plug of silica gel. Evaporation of the solvent
was dissolved, KCN (0.452 g, 6.94 mmol) was added, and the
mixture was stirred at rt for 24 h. CH Cl (100 mL) and H O (100
mL) were added, the organic phase was separated and washed
with H O (4 × 100 mL). After drying over MgSO , the mixture
) δ 115 was filtered and the solvent removed. The residue was purified by
0.12 (s, 1H), 7.78–7.76 (m, 1H), 7.56–7.48 (m, 2H), 7.39 (td, column chromatography (silica gel, gradient hexanes/CH Cl 2:1
and drying in vacuo afforded the product 5 (0.695 g, 62%) as a
2
2
2
yellow oil. R
f 2 2
= 0.49 (hexanes/CH Cl 1:1). IR (ATR) 3067 (vw),
2
983 (w), 2927 (w), 2874 (w), 2822 (w), 2736 (w), 1691 (s) 1599
2
4
–
1
1
(
m), 1574 (m), 1451 (m) cm ; H NMR (300 MHz, CDCl
3
1
2
2
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 5

Organic & Biomolecular Chemistry
Page 6 of 7
→
0:1) to afford the product 9 (51 mg, 89%) as a purple solid.
Mp 180–182 °C. R = 0.41 (hexanes/CH Cl
) λmax (ε) 419 (546000), 516 (21100), 552 (10000), 591
6070), 646 (5440) nm; IR (ATR) 3314 (w), 2923 (m), 2855 (w),
J = 5.0 Hz, 2H), 8.68 (d, J = 5.0 Hz, 2H), 8.51 (d, J = 4.9 Hz,
f
2
2
1:1). UV-vis 60 2H), 7.96–7.82 (m, 7H), 7.69–7.63 (m, 1H), 7.55 (t, J = 6.9 Hz,
View Article Online
(
(
CH
2
Cl
2
2H), 7.48 (d, J = 8.2 Hz, 2H), 7.38 (d, J = 8.2 Hz, 4H), 3.24 (s,
DOI: 10.1039/C5OB00836K
2H), 2.90 (t, J = 7.7 Hz, 2H), 2.82 (t, J = 7.7 Hz, 4H), 1.91–1.74
–
1
1
13
5
0
5
0
5
0
5
0
5
0
5
1465 (m), 1346 (m) cm ; H NMR (300 MHz, CDCl
.88 (m, 6H), 8.61 (d, J = 4.8 Hz, 2H), 8.17–8.08 (m, 7H), 7.98
d, J = 7.2 Hz, 1H), 7.87 (td, J = 7.6 Hz, J = 1.3 Hz, 1H), 7.73 (t, 65 140.6, 138.1, 138.0, 134.9, 133.9, 133.64, 133.59, 132.5, 132.21,
3
) δ 8.90–
(m, 6H), 1.62–1.44 (m, 6H), 1.09–1.01 (m, 9H); C NMR
8
3
(100 MHz, CDCl ) δ 175.2, 142.9, 142.8, 142.4, 142.34, 142.27,
(
J = 6.9 Hz, 1H), 7.57 (d, J = 8.1 Hz, 6H), 3.39 (s, 2H), 2.97 (t,
J = 7.7 Hz, 6H), 1.92 (pent, J = 7.6 Hz, 6H), 1.60 (sext,
132.17, 131.5, 129.3, 128.6, 126.9, 126.8, 125.7, 119.3, 119.1,
115.8, 38.6, 35.6, 35.5, 33.8, 33.7, 22.6, 22.5, 14.10, 14.07 (1
1
3
1
1
2
2
3
3
4
4
5
5
J = 7.4 Hz, 6H), 1.10 (t, J = 7.3 Hz, 9H), –2.73 (s, 2H); C NMR
75 MHz, CDCl ) δ 142.4, 141.3, 139.3, 139.0, 134.6, 134.5,
34.3, 132.0, 131.2 (br), 129.3, 127.5, 126.8, 126.72, 126.65, 70 calcd. for C58
21.1, 120.6, 117.8, 115.0, 35.6, 33.8, 22.8, 22.6, 14.1 (12 signals 941.3303.
signal coincident or not observed). ESI HRMS m/z calcd. for
+
(
3
C
58
H
54
N
4
NaNiO
2
([M + Na] ) 919.3493, found 919.3486; m/z
+
1
1
53 4 2 2
H N Na NiO ([M – H + 2Na] ) 941.3312, found
coincident or not observed). ESI HRMS m/z calcd. for C58
H
56
N
5
+
([M + H] ) 822.4530, found 822.4513.
Acknowledgements
Porphyrin 10. Porphyrin
9
(39 mg, 0.047 mmol) was
(4 mL) and H O (1.3 mL)
We are grateful for the financial support from the Institute for Oil
Sands Innovation at the University of Alberta, the Natural
Sciences and Engineering Research Council of Canada, and the
Graduate School Molecular Science (GSMS) at FAU. We thank
Dr. Alexander Scherer for his assistance, as well as Prof. Jürgen
Schatz and Dr. Max von Delius for helpful discussions regarding
assessment of the binding constants.
dissolved in AcOH (4 mL). H
2
SO
4
2
were added and the mixture heated to 95 °C for 90 h. The dark
green solution was cooled to rt and poured into ice water
(15 mL), whereupon a green precipitate formed. The solid was
7
5
collected by filtration, washed with H
in CH Cl (50 mL). The solution was washed with H
mL), a mixture of an aqueous saturated solution of NaHCO
O (2:1, 150 mL), and H O (50 mL). The solution was dried
over MgSO and filtered. The solvent was removed and the
residue was purified by column chromatography (silica gel,
CH Cl /EtOAc 9:1) to afford the product 10 (37 mg, 94%) as a
purple solid. Mp 255–258 °C. R = 0.58 (CH Cl /acetone 19:1).
2
O (50 mL), and dissolved
O (3 × 50
and
2
2
2
3
H
2
2
80
Notes and references
4
a
Department of Chemistry and Pharmacy & Interdisciplinary Center of
Molecular Materials (ICMM), Friedrich-Alexander-Universität
Erlangen-Nürnberg (FAU), Henkestraße 42, 91054 Erlangen, Germany.
Fax: +49-9131-85-26865; Tel: +49-9131-85-22540; E-mail:
rik.tykwinski@fau.de
2
2
f
2
2
UV-vis (THF) λmax (ε) 418 (567000), 514 (22500), 549 (10800),
85
592 (6220), 647 (4550) nm; IR (ATR) 3314 (w), 3021 (w), 2953
b
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G
–
1
(
m), 2924 (m), 2855 (m), 1707 (m), 1467 (m), 1347 (m) cm ;
2G2, Canada
1
Electronic supplementary information (ESI) available: NMR spectra of
compounds 3–10, 2D NMR spectra of compound 4, as well as
experimental details and NMR data of the aggregation studies.
H NMR (300 MHz, CDCl
J = 4.8 Hz, 2H), 8.77 (d, J = 4.8 Hz, 2H), 8.61 (d, J = 4.8 Hz,
H), 8.14–8.00 (m, 7H), 7.76–7.68 (m, 1H), 7.58 (t, J = 8.9 Hz,
4H), 7.49 (d, J = 7.4 Hz, 2H), 7.36 (d, J = 6.8 Hz, 2H), 3.37 (s,
H), 2.97 (t, J = 7.7 Hz, 2H), 2.85 (t, J = 7.6 Hz, 4H), 1.97–1.78
m, 6H), 1.67–1.47 (m, 6H), 1.13–1.03 (m, 9H), –2.74 (br s, 2H);
3
) δ 8.86 (d, J = 4.9 Hz, 2H), 8.83 (d,
90
2
1
.
K. Aleklett, M. Höök, K. Jakobsson, M. Lardelli, S. Snowden and B.
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(
1
2
.
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C NMR (100 MHz, CDCl
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95
3. I. Gawel, D. Bociarska and P. Biskupski, Appl. Catal., A, 2005, 295,
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1
39.2, 135.4, 134.6, 134.51, 134.46, 134.41, 131.1 (br), 129.3,
8
128.6, 126.7, 126.6, 125.5, 120.6, 120.3, 116.7, 38.9, 35.7, 35.6,
3.8, 33.7, 22.63, 22.58, 14.14, 14.10 (6 signals coincident or not
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.
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3
+
observed). ESI HRMS m/z calcd. for C58
H
57
N
4
O
2
([M + H] )
NaO
2
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41.4476, found 841.4476; m/z calcd. for
C
58
H
56
N
4
+
100
(
[M + Na] ) 863.4296, found 863.4314.
Porphyrin 3. Porphyrin 10 (14.7 mg, 0.0175 mmol) was
dissolved in CHCl (20 mL), and a solution of Ni(OAc) ·4H
0.100 g, 0.402 mmol) in MeOH (5 mL) was added. After heating
to reflux for 24 h in the dark, the solution was cooled to rt,
washed with H O (2 × 50 mL), a mixture of H
O and an aqueous 105
saturated solution of NaHCO (9:1, 50 mL), and H O (50 mL).
The organic layer was dried over MgSO and filtered. After
removal of the solvent, the residue was purified by column
chromatography (silica gel, gradient CH Cl /acetone 1:0 → 15:1)
3
2
2
O
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014/0234026, August 21, 2014.
(
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1
953 (s), 2926 (s), 2859 (m), 1709 (m), 1460 (m), 1352 (m) cm ;
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