A photocatalyst-enzyme coupled artificial photosynthesis system for solar energy in production of formic acid from CO2

Article abstract of DOI:10.1021/ja3009902

The photocatalyst-enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO₂. The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO₂.

Full text of DOI:10.1021/ja3009902

Article
pubs.acs.org/JACS
A Photocatalyst−Enzyme Coupled Artificial Photosynthesis System
for Solar Energy in Production of Formic Acid from CO
2
†
†
,†
†
†
‡
Rajesh K. Yadav, Jin-Ook Baeg,* Gyu Hwan Oh, No-Joong Park, Ki-jeong Kong, Jinheung Kim,
†
†
Dong Won Hwang, and Soumya K. Biswas
†Advanced Chemical Technology Division, Korea Research Institute of Chemical Technology, 100 Jang-dong, Yuseong, Daejon,
05-600, Republic of Korea
3
‡
Department of Chemistry and Nano Science, Ewha Womans University, 11-1 Daehyun-dong, Seodaemun-gu, Seoul, 120-750,
Republic of Korea
*
S Supporting Information
ABSTRACT: The photocatalyst−enzyme coupled system for artificial
photosynthesis process is one of the most promising methods of solar
energy conversion for the synthesis of organic chemicals or fuel. Here we
report the synthesis of a novel graphene-based visible light active
photocatalyst which covalently bonded the chromophore, such as
multianthraquinone substituted porphyrin with the chemically converted
graphene as a photocatalyst of the artificial photosynthesis system for an
efficient photosynthetic production of formic acid from CO . The results
2
not only show a benchmark example of the graphene-based material used as
a photocatalyst in general artificial photosynthesis but also the benchmark
example of the selective production system of solar chemicals/solar fuel directly from CO2.
1
. INTRODUCTION
having remarkable electronic, thermal, optical, and mechanical
properties.
Recently, there are some reported examples of graphene and
photocatalyst composite. They are simple composites of metal
9
,10
The direct conversion of solar energy into chemical energy for
the production of renewable and nonpolluting fuels remains a
great and fascinating challenge for this century. One of the
most promising methods of solar energy conversion for the
synthesis of organic chemicals or fuel is artificial photosyn-
oxide semiconductor photocatalyst, such as TiO and
2
1
1,12
graphene.
But the graphene and metal oxide semiconductor
1
−3
thesis.
Many approaches to artificial photosynthesis have
composite could not be suitable as a photocatalyst for the
photocatalyst−biocatalyst coupled system because of intrinsic
low-energy level of the conduction band edges.
The small energy difference between the conduction band
edges of metal oxide and the reduction potential of rhodium
complex makes it difficult to transfer the photoexcited electrons
in the metal oxide into the reduction center and finally results
in very low efficiency of the NADH regeneration.
been explored, and some of these employ photocatalysts, such
as semiconductors, transition-metal complexes, and so on.
Although photocatalytic artificial photosynthesis has proved to
be feasible, many problems still remain, such as low conversion
efficiency, low selectivity of products, and stability problems of
4
the photocatalyst when conventional setups are used.
In an earlier work, we reported W Fe Ta O to be a5
2
4
2
17
photocatalyst for a photocatalyst−enzyme coupled system.
The photocatalyst−enzyme coupled system is one of the most
ideal artificial photosynthesis systems which utilizes solar
energy for the synthesis of various chemicals and fuel. For
practical use of the photocatalyst−enzyme coupled artificial
photosynthesis process, one of the most challenging tasks is the
search for a highly efficient visible light active material which
acts as a photocatalyst in the reduced nicotinamide adenine
dinucleotide (NADH) regeneration system and triggers
enzymatic production of solar chemicals/solar fuel from
CO . Since energetically 46% of the total solar light available
on earth is in the visible range and only 4% is in the UV range,
it is imperative that the photocatalysis must be visible light
functional for real and meaningful solar energy conversion.
Graphene has proved to be a mounting superstar in the fields
Here we report the synthesis of a novel graphene-based
visible light active photocatalyst which covalently bonded the
chromophore, such as multianthraquinone substituted porphyr-
13
in (MAQSP) with the chemically converted graphene (CCG)
as a photocatalyst of the photocatalyst−enzyme coupled system
for an efficient artificial photosynthetic production of formic
acid from CO . The results not only show a benchmark
2
example of the graphene-based material used as a photocatalyst
in general artificial photosynthesis but also the benchmark
example of the selective production system of solar chemicals/
5
2
6
solar fuel directly from CO2.
Received: January 31, 2012
Published: July 6, 2012
7
,8
of material science, condensed-matter physics, and chemistry
©
2012 American Chemical Society
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. RESULTS AND DISCUSSION
.1. A Photocatalyst−Biocatalyst Coupled Artificial
Photosynthesis System. A diagrammatic representation of
the photocatalyst−biocatalyst coupled system based on the
synchronized working mechanism of photocatalysis and
biocatalysis involved in the formation of formic acid from
Article
+
2
transfers electrons and a hydride to NAD , which gets
converted to NADH thus forming the photocatalysis cycle.
In this way, the rhodium complex shuttles as an electron
mediator between the graphene photocatalyst and NAD ,
proving as an efficient factor for regeneration of the NADH
cofactor. Finally, NADH is consumed by the CO substrate for
5
2
+
2
its enzymatic (formate dehydrogenase) conversion to formic
acid. The NAD+ released from the enzyme can undergo
photocatalysis cycle in the same way, leading to the
photoregeneration of NADH. These two catalysis cycles thus
couple integrally to work together, ultimately yielding formic
acid from CO2.
CO is shown in Scheme 1.
2
Scheme 1. Graphene-Based Photocatalyst Catalyzed
Artificial Photosynthesis of Formic Acid From CO under
Visible Light
2
The chemically converted graphene coupled multianthraqui-
none substituted porphyrin (CCGCMAQSP) used as a
photocatalyst in the photobioreactor was synthesized via
multistep synthesis involving the substitution of 1-amino-
anthraquinone moieties (AAQ) linked by 1,3,5-trichlorotriazine
(
(
TCT) units to a 5,10,15,20-tetrakis(4-aminophenyl)porphyrin
TkisAPP) core to enhance the efficiency of light energy
harvesting.
2
.2. Characterization of Graphene-Based Photocata-
lyst. The XRD (Model: Rigaku D/Max-2200 V X-ray
diffractometer and Cu Kα radiation) pattern of CCG exhibits
a weak and broad characteristic peak of CCG which appeared at
the 2θ value of 22.5°. The peak at 22.5° corresponds to the
interlayer spacing (d-spacing) in CCG of about 0.39484 nm
which is very close to that of naturally available graphite, 0.335
The graphene-based photocatalyst is a material which
covalently bonded the chromophore (as an electron donor),
such as anthraquinone substituted porphyrin with the chemi-
cally converted graphene (as an electron acceptor). The
absorption of photon occurs as a transition between localized
orbitals around chromophore (MAQSP). The created electrons
reach to the rhodium complex via graphene. An organometallic
13
nm. The slightly higher value of this interlayer distance in
CCG compared to that in graphite indicates the presence of a
15
small amount of −COOH groups remaining in CCG which
participate in the formation of a new −CONH− bond with
MAQSP.
14
rhodium complex easily receives the electron and is reduced.
It further abstracts a proton from aqueous solution and
Figure 1. (a) 3D structure of the graphene-based photocatalyst (CCGCMAQSP). AFM and TEM images of (b) CCG and (c) CCGCMAQSP.
1
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Figure 2. (a) UV absorption spectroscopy of CCGCMAQSP, MAQSP, TkisAPP, AAQ, and TCT. (b) FTIR spectra of CCG and CCGCMAQSP.
c) TGA of the CCG and CCGCMAQSP. (d) DSC of the CCG and CCGCMAQSP.
(
Formation of the proposed photocatalyst, CCGCMAQSP,
nm, while CCGCMAQSP exhibits higher absorption at the
through generation of the −CONH− bond by the coupling
reaction between CCG and MAQSP is suggested by the
appearance of a weak and broad peak at the 2θ value of 23.5° in
the XRD of CCGCMAQSP (see Supporting Information).
Figure 1 shows 3D structure of the graphene-based
photocatalyst (CCGCMAQSP) and atomic force microscopy
same range.
This demonstrates that in the ground-state attachment of the
MAQSP core has relaxed the electronic properties of CCG
thereby proving the high efficiency of CCGCMAQSP as a
photocatalytic energy for NADH regeneration, which is
indispensable in the enzymatic production of solar chemicals/
fuels from CO2.
(AFM) and TEM images of the CCG and CCGCMAQSP.
The graphene (CCG) and the photocatalyst (CCGMAQSP)
The FTIR (Bruker, ALPHA-T FT-IR spectrometer) studies
gave a clear evidence for the coupling of MAQSP with CCG
and the reduction of CCG. The inset shows prolonged plots of
were imaged using AFM as shown in Figure 1b,c and Figure S1,
Supporting Information. The samples for AFM investigations
were prepared by ultrasonic treatment of CCG and
CCGMAQSP (in DMF) dispersions of 0.0003 g/L. The
samples were prepared through drop-casting on a cleaned glass
surface. The roughness of CCG and CCGMAQSP are 1.156
and 1.836 nm (Figure 1b and 1c). The thickness of CCG and
CCGMAQSP are 1.194 nm and 1.997 nm (Figure S1. a and b,
see Supporting Information). It depicts that the edge of CCG
has been roughened by the coverage of soft material indicating
the presence of covalently attached MAQSP. The morphology
of synthesized CCG and CCGCMAQSP was also characterized
by AFM and TEM (Figure 1b,c). The TEM (Figure 1b) result
indicated that the CCG existed in the single layer. Surface
morphology of CCG (AFM and TEM, Figure 1b) also has been
changed after the covalently attached MAQSP (AFM and
TEM, Figure 1c). The topographical height of CCGMAQSP
−1
the CCG (Figure 2b) spectra from 1000 to 1750 cm . The
−1
ν
spectra show important bands around 1060 cm ( C−O),
1220 cm− ( phenolic), 1370 cm ( O−H bending in tertiary
1
ν
−1 ν
−1
ν
−1
alcohol), 1620 cm ( HOH bending in water), and 1720 cm
ν
( CO).
After reduction these peaks disappear, and a new peak
−1
appears at 1705 cm , which is obvious in CCG. In the
spectrum of CCGCMAQSP, the peak at 1705 cm− almost
1
−1
disappears, and a new broad band emerges at 1617 cm , which
corresponds to the CO characteristic stretching band of the
amide group (−NHCO−). The C−N stretching band of the
amide group which appears at 1235 cm− clearly indicates the
presence of amide linkage (−NHCO−) in the structure,
thereby showing the coupling of MAQSP with CCG.
1
The thermal behavior of CCG and CCGCMAQSP was
investigated by thermogravimetric analysis (TGA, model: Q
500) (Figure 2c) in the temperature range from 25 to 900 °C
and differential scanning calorimetry (DSC, model: 2910)
(Figure 2d) at a heating rate of 5 °C min− under Ar flow in the
temperature range from 25 to 400 °C. CCG exhibits slow
weight loss with an increase of temperature up to 800 °C. The
TGA curve for CCGCMAQSP shows a two-step weight loss. A
steady weight loss up to 37.56% in the temperature range from
1
.997 nm is also attributed to covalently linked MAQSP to
1
6
CCG.
The UV absorption studies of TCT, AAQ, TkisAPP,
MAQSP, and CCGCMAQSP have been conducted in DMF.
CCGCMAQSP (Figure 2a) showed a strong Soret band
absorption at 475 nm, which is consistent with that of MAQSP.
1
17
This type of observation has been already reported. TCT,
AAQ, TkisAPP, and MAQSP exhibit low absorption near 300
1
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2
5 °C to ∼100 °C corresponds to the typical pattern of sidewall
functionalization. This is followed by the second major weight
loss in the temperature range from 180 to 380 °C with an
exothermic peak appearing at around 340 °C in the DSC curve
(
Figure 2d), indicating the breaking of the amide bonds within
18
the MAQSP system.
For confirmation of the coupling of MAQSP with CCG and
the restoration of CCG to CCGCMAQSP in the existence of
MAQSP were carried out by Raman (model: Bruker/
SENTERRA) and by XPS (model: KARTOS AXIS NOVA),
respectively (see Supporting Information). In uncorroded
−1
single-layer graphene, the disorder band of 1350 cm was
−1
hardly noticeable, but the 1350 cm mode consequently
developed after the oxidation began. There is a practical
−
1
correlation between the intensity (I) ratio of the 1350 cm
−1
mode to that of the 1625 cm mode (I1350/I1625) as reported
Figure 3. Photocurrent response of FTO/CCGCMAQSP and FTO/
MAQSP electrode under illumination of simulated sun light [1sun]
(three electrodes; platinum counter electrode, Ag/AgCl reference
electrode, glassy carbon working electrode, 0.1 M NaCl aqueous
solution containing 0.4 M TEOA as a redox couple/electrolyte and
scan rate of 100 mV/s).
1
9
elsewhere. From the Raman spectra, it is obvious that the
insignificant (I1350/I1625) ratio reveals the singularity of the
CCG layer. Moreover, coupling of CCG with MAQSP leads to
a shift in the band (see Supporting Information). The
incorporation of MAQSP into the CCG material leads to a
−1
prominent Raman shift in the 2000−500 cm region. We
observed considerable shifts at the 1350 and 1625 cm− bands
1
CCGCMAQSP for the visible light-driven photoregeneration
of NADH. The concentration of photoregenerated NADH was
−1
of the spectra of CCGCMAQSP at 500 and 1125 cm ,
respectively.
5
measured by spectrophotometer. As shown in Figure 4,
Energy-dispersive X-ray spectroscopy (EDS, model: Bruker/
Quantax 200) analysis showed that CCG is composed of
carbon (73.12 atom %), oxygen (26.28 atom %), and MAQSP
samples with carbon (68.29 atom %), oxygen (11.78 atom %),
and nitrogen (19.93 atom %), respectively. Furthermore, the
impurity of unwanted materials is undetectable in the sample as
shown in the Supporting Information data. It is apparent that
the CCG becomes smoother after the attachment of MAQSP,
and the ratio of the CCGCMAQSP contents (O/C) is
somewhat lower than that of CCG as a result of the presence
CCGCMAQSP is significantly effective for NADH photo-
regeneration constantly accumulated up to 45.54% with a time
linearity. However, W Fe Ta O photocatalyst and MAQSP
2
4
2
17
2
0
of nitrogen.
The BET surface area of CCG (254 m g ) is very close to
2
−1
21
the reported value. The BET measurement of CCGMAQSP
2
−1
(
189.01 m g ) gives a little lower value than CCG, which is
due to the MAQSP on the CCG.
.3. Photoelectrochemical Measurement. Transient
2
photocurrent were measured on a photoelectrochemical test
device fabricated by drop-casting the covalently attached
CCGCMAQSP hybrid material dispersed in ethanol (0.09 g/
mL) onto fluorine-doped tin oxide (FTO) coated glass. The
Figure 3 shows the photocurrent response versus time of
MAQSP and CCGCMAQSP photocatalyst. It is found that the
photocurrent of the CCGCMAQSP photocatalyst is much
higher than MAQSP. The photocurrent response of the
CCGCMAQSP hybrid material is reasonably reversible and
stable, from which we can see that the current can reproducibly
increase severely under each irradiation and quickly recover in
the dark. The stable photocurrent property of our photocatalyst
(
CCGCMAQSP) is also in agreement with many observations
for graphene hybrid materials and composites, which showed a
2
2,23
stable photocurrent.
Therefore the observed photocurrent
represents charge transportation through a photocatalyst
(
CCGCMAQSP) to the collecting electrode (FTO glass)
24
surface.
Figure 4. Photocatalytic activities of CCGCMAQSP, MAQSP, and
2
.4. Photocatalytic NADH Regeneration and Photo-
W Fe Ta O in NADH photoregeneration and visible-light driven
2
4
2
17
synthetic Production of Formic Acid from CO . A series of
photocatalysis experiments was performed to study the
photocatalytic activities of W Fe Ta O , MAQSP, and
2
artificial photosynthesis of formic acid from CO . (a) NADH
2
photoregeneration and (b) visible-light driven artificial photosynthesis
of formic acid from CO2.
5
2
4
2
17
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give only 14.50% and 23.79% yield of NADH regeneration,
respectively (Figure 4a).
the photoexcited MAQSP is forbidden. Thus, the photoexcited
electrons created in MAQSP can be easily transferred into
CCG, not reversely. The huge surface area and the extremely
Additional experiments were performed to study the
photocatalytic performance of W Fe Ta O , MAQSP, and
27
high carrier mobility of graphene raise the probability for
electrons to be transferred into rhodium complex, eventually
accelerating the chemical reactions of NADH generation.
Furthermore, the graphene also acts as an electron reservoir to
transport multiple electrons. In most molecular systems, the
energy cost of electron addition is very high because of large
Coulomb repulsion between localized electrons. In graphene,
the multielectron addition or removal can be possible because
of the delocalized nature of wave functions over the whole
graphene surface (extending several μm).
2
4
2
17
CCGCMAQSP for the visible light-driven artificial photosyn-
thesis of formic acid from CO . The amount of formic acid was
2
detected by GC (7890A, Agilent Technologies). As shown in
Figure 4b, the formic acid yield increases linearly with the
reaction time when CCGCMAQSP is used as a photocatalyst.
The efficiency of CCGCMAQSP for the production of formic
acid for 2 h was 110.55 μmol, while W Fe Ta O and MAQSP
2
4
2
17
were 14.25 and 46.53 μmol, respectively. These investigations
clearly reveal the superiority of the graphene-based photo-
catalyst (CCGCMAQSP) over the other photocatalysts.
To elucidate the origin of the photocatalytic activity and the
activity enhancement of the graphene-based photocatalyst
3. CONCLUSION
In summary, we presented here a new graphene-based
photocatalyst (CCGCMAQSP) for artificial photosynthesis.
The photocatalyst (CCGCMAQSP) has been fully charac-
terized through spectroscopy, thermal analysis, and microscopy.
Moreover, photoelectrochemical studies together with DFT
calculation have allowed the evaluation of photoelectrochemical
property and the origin of the photocatalytic activity of the
photocatalyst. The CCGCMAQSP is a highly active visible light
photocatalyst of the photocatalyst−enzyme coupled system for
an efficient artificial photosynthetic production of formic acid
(CCGCMAQSP), we have performed a series of first-principles
calculations using plane-wave-based density functional theory
25
(
DFT) code, VASP. To overcome the computational limit
imposed by the large size of molecular system, we divided the
CCGCMAQSP into two parts, CCG composed of 30 hexagon
rings and MAQSP, which were saturated by carboxyl and amine
groups, respectively, and then performed electronic structure
calculations separately (Figure 5).
from CO . This opens possibilities of applications for graphene-
2
based materials, especially in the field of artificial photosyn-
thesis. One of the most challenging tasks for practical use of the
photocatalyst−biocatalyst coupled system for artificial photo-
synthesis process is the search for a highly efficient visible light
active material which acts as a photocatalyst in the NADH
regeneration system and triggers enzymatic production of solar
chemicals/solar fuel from CO . Thus, the present work
2
demonstrates successfully a new and promising the graphene-
photocatalyst-based artificial photosynthetic system for the
ultimate goal of solar energy utilization in tailor-made synthesis
of fine chemicals and solar fuel from CO2.
4
. EXPERIMENTAL SECTION
4
.1. Materials. All chemicals were purchased from Aldrich.
Figure 5. Visualization of the molecular orbitals (LUMO and
HOMO) of the (a) CCG and (b) MAQSP as obtained at the DFT-
GGA level of approximation.
Enzyme (formate dehydrogenase) and β-nicotinamide adenine
dinucleotide (β-NAD) were purchased from Sigma. Graphite powder
99.9995%, 325 mesh) was purchased from Alfa Aesar.
(
4
.2. Synthesis of Graphene Oxide. The graphene oxide was
2
8
It is well-known that the Kohn−Sham eigenvalues obtained
in DFT should not be directly interpreted as electron removal/
addition energies because the method does not satisfy
Koopman’s theorem. However, DFT results can give clues
regarding the peak shift of optical absorption and the direction
of electron transport.
prepared according to reported method: Into 0.115 L of sulfuric acid,
5.0 g of powdered graphite (325 mesh) and 2.5 g of sodium nitrate
were added. The ingredients were mixed in a 10 L battery jar that had
been cooled to 0 °C in an ice bath as a safety measure. While
maintaining vigorous agitation, 15.0 g of potassium permanganate was
added to the suspension. The rate of addition was controlled carefully
to prevent the temperature of the suspension from exceeding 20 °C.
The ice bath was then removed, and the temperature of the suspension
brought to 35 °C for 30 min. As the reaction progressed, the mixture
gradually thickened and effervescence ceased. At the end of 20 min,
the mixture became brownish gray paste with evolution of only a small
amount of gas. After 30 min, 2.3 L of water was slowly stirred into the
paste, causing violent effervescence and an increase in temperature to
26
The incident light is absorbed at MAQSP, where photo-
excitation occurs, and the created electrons move into the CCG
via a stable amide bond. The electron-transfer efficiency could
be estimated by the energy level alignment between the
conduction band edges of CCG and the lowest unoccupied
molecular orbital (LUMO) of MAQSP. From our DFT
calculation results, we have confirmed that the energy level of
each segment is aligned for electrons to transfer from MAQSP
finally to hydrogen reduction site via CCG. The Fermi level of
graphene, which is calculated to be 4.14 eV lower than vacuum
level, lies at the center of bandgap of MAQSP. The calculated
bandgap of MAQSP is ∼0.6. By the usage of triethanolamine
9
1
8 °C. The diluted suspension was maintained at this temperature for
5 min. The suspension was then further diluted to approximately 7 L
of warm water and treated with hydrogen peroxide to reduce the
residual permanganate and manganese dioxide to colorless soluble
manganese sulfate. Upon treatment with the peroxide, the suspension
turned bright yellow. The suspension was filtered resulting in a yellow-
brown, i.e., cake type. The filtering was conducted while the
suspension was still warm to avoid precipitation of the slightly soluble
(
TEOA)as a hole scavenger, the electron transfer from CCG to
1
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salt of mellitic acid formed as a side reaction. After washing the
yellowish-brown filter cake three times with a total of 7 L of warm
water, the graphitic oxide residue was dispersed in 16 L of water to
approximately 0.285 g solid. The remaining salt impurities were
removed by treating with resinous anion and cation exchangers. The
dry form of graphitic oxide was obtained by centrifugation followed by
mL of sodium phosphate buffer (100 mM, pH 7.0). The regeneration
of NADH was monitored by a spectrophotometer (UV-1800,
Shimadzu).
4.8. Artificial Photosynthesis of Formic Acid from CO
. The
2
artificial photosynthesis of formic acid from CO was also performed
2
within a quartz reactor under an inert atmosphere at room
temperature, and a 450 W xenon lamp with a 420 nm cutoff-filter
was used as a light source. The reaction was composed of
photocatalyst (0.5 mg), β-NAD (1.24 μmol), rhodium complex
(0.62 μmol), and formate dehydrogenase (3 units) in 3.1 mL of
sodium phosphate buffer (100 mM, pH 7.0) with TEOA (1.24 mmol)
15
dehydration at 40 °C over phosphorus pentoxide.
4.3. Preparation of Chemically Converted Graphene from
Graphene Oxide. For the reduction procedure, dry graphene oxide
was dispersed in deionized water to give a colloidal solution. The pH
of this solution was adjusted to 9−10. Sodium borohydride was
directly added into the solution of graphene oxide dispersion under
magnetic stirring, and the mixture was kept at 80 °C for 1 h with
constant stirring. The reduced product was filtrated and washed with
large amounts of water several times to remove most residual ions.
This moderately reduced graphene oxide was kept in vacuum
desiccators with phosphorus pentoxide for two days, redispersed in
concentrated sulfuric acid, and heated to 120 °C with stirring for 12 h.
After cooling down, the dispersion was diluted with deionized water.
in the presence of CO (flow rate: 0.5 mL/min). After bubbling of
2
CO for 1 h without light (light off), the reactor was exposed to visible
2
light (light on). The amount of formic acid was detected by GC
(7890A, Agilent Technologies).
ASSOCIATED CONTENT
■
*
S
Supporting Information
15
Synthesis of CCGCMAQSP scheme, XRD, RAMAN, and XPS
data available. This material is available free of charge via the
Internet at http://pubs.acs.org.
The final product was separated by filtration.
.4. Preparation of 5,10,15-[(4-{(3,5-Tris-(dichlorotriazine)}-
aminophenyl)-20-aminophenyl porphyrin] Synthesis of
,10,15-[(4-{(3,5-Tris-(diamino-anthraquinone)triazine}-
inophenyl)-20-aminophenyl porphyrin]. A solution of 5,10,15-
(4-{(3, 5-Tris-(dichlorotriazine)}aminophenyl)-20-aminophenyl por-
phyrin] in THF, amino-anthraquinone (6 mmol), and triethylamine
6.6 mmol) was added and stirried at 80 °C for 10 h. The completion
4
5
AUTHOR INFORMATION
[
■
Corresponding Author
jobaeg@krict.re.kr
(
of the reaction was monitored by thin-layer chromatography (TLC).
The solvent was removed, and the residue was purified by column
chromatography on silica gel using CH Cl /ethyl acetate (50:1 v/v) as
Notes
The authors declare no competing financial interest.
2
2
eluent. The title compound was isolated 53% yield. 1H NMR (CGCl3,
δ in ppm): 9.31 (s, 9Haromatic secondary amine), 9.13 (d, 6H ), 8.70 (s,
ACKNOWLEDGMENTS
g
■
8Hpyrrol), 8.67(m, 18Hf+c+b), 8.51 (m, 18Ha+d+e), 8.46 (d, 8Hi+k, J = 6.6
This work was supported by the KRICT 2020 project program.
Hz), 7.72 (d, 8Hh+j), 4.20 (s, 2Hamine), −2.78 (s, 2Hpyrrol−NH); LC/MS,
+
29,30
ESI (m/z): 2237.78 (M ).
.5. Preparation of CCGCMAQSP. CCG (50 mg) and MAQSP
150 mg) were stirred in DMF (50 mL) in the presence of a catalytic
2
9
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4
■
(
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3
2
2
same above procedure. UV spectroscopy and TLC were used to check
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2
remove acid−amine impurities, and eventually dried under vacuum to
2
8,30
yield the hybrid CCGCMAQSP.
The photocatalyst
(
CCGCMAQSP) was analyzed by AFM, FTIR, TGA, DSC, XRD,
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