Preparation and reactivity of vitaminB12-TiO2 hybrid catalyst immobilized on a glass plate

Article abstract of DOI:10.1246/bcsj.20090234

The vitaminB₁₂-TiO₂ hybrid catalyst was effectively immobilized on a glass plate, and the immobilized catalyst shows an efficient reactivity for various molecular transformations, such as the 1,2-migration of a phenyl group and dechlorination of perchloroethylene during irradiation by UV light.

Full text of DOI:10.1246/bcsj.20090234

170
Bull. Chem. Soc. Jpn. Vol. 83, No. 2, 170–172 (2010)
Short Articles
+
HOOC
COOH
CH3
CH3
H
Preparation and Reactivity of
Vitamin B12-TiO2 Hybrid Catalyst
Immobilized on a Glass Plate
COOH
HOOC
H3C
H3C
X
N
Co
H
H
CH3
N
H
N
H
N
CoIII
B12
Y
=
HOOC
CH3
H3C
H
CH3
COOH
Hisashi Shimakoshi, Makoto Abiru,
Keita Kuroiwa, Nobuo Kimizuka,
COOH
Cl-
X = CN, Y = H2O
[(CN)(H2O)Cob(III)7COOH]Cl
³
Midori Watanabe, and Yoshio Hisaeda*
Department of Chemistry and Biochemistry,
Graduate School of Engineering, Kyushu University,
744 Motooka, Fukuoka 819-0395
TiO2
TiO2
TiO2
TiO2
TiO2
TiO2
TiO2
TiO2
TiO2
Received September 3, 2009
E-mail: yhisatcm@mail.cstm.kyushu-u.ac.jp
Glass matrix
Figure 1. Schematic representation of B12-TiO2 glass plate.
The vitamin B12-TiO2 hybrid catalyst was effectively
immobilized on a glass plate, and the immobilized catalyst
shows an efficient reactivity for various molecular trans-
formations, such as the 1,2-migration of a phenyl group and
dechlorination of perchloroethylene during irradiation by UV
light.
lost and contaminated the product solution. To improve this
step, the B12-TiO2 hybrid catalyst was immobilized on a glass
plate as shown in Figure 1 since one of the merits of the TiO2
particle is that it is easily attached to the surface of various
substrates, such as glass.7
The B12-TiO2-coated glass plate was prepared by the
following procedure. A TiO2 sol solution was deposited on a
freshly cleaned slide glass substrate by dip coating, and then
the glass plate was immersed in a 10 mM aqueous solution of
the B12 derivative. The glass plate was dried at room temper-
ature. The prepared hybrid glass plate was characterized by
UV-vis, XPS, XRD, and SEM. From the UV-vis absorption
spectrum, the characteristic absorption maxima of B12 were
observed at 352, 455, 498, and 529 nm, and the apparent
Immobilized catalyst is generally considered to hold many
advantages, such as utilization of small amounts of catalyst,
usable in various media, and ready separation of products and
catalyst.1 The catalyst can be recovered and recycled resulting
in reducing waste generated. Cobalt complexes, i.e. vitamin B12
derivatives (B12), are good catalysts for several molecular
transformations,2 and efforts toward immobilization of vitamin
B12 derivatives on various supports have been achieved by
several groups.3 Utilizing the property of B12 derivative to react
with various organic halides by dehalogenation in the Co(I)
state, an efficient dehalogenation system has been constructed.4
Furthermore, cleavage of the cobalt-carbon bond of the
intermediately formed alkylated complex should afford radical
species which can be utilized for radical-mediated organic
reactions.5 Recently, we reported the construction of a B12
catalytic system utilizing titanium dioxide as a photosensitizer.6
The UV light irradiation of the hybrid catalyst composed of the
B12 derivative (cyanoaquacobyrinic acid) and TiO2 promoted
several molecular transformations such as the dechlorination of
1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) and 1,1-
dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), the 1,2-migra-
tion of a phenyl group, and ring-expansion reactions.6 In this
catalyst, immobilized B12 on TiO2 was reductively activated by
band gap excitation of TiO2 with UV light irradiation. The
present study further advanced this B12-TiO2 hybrid catalytic
system from the viewpoint of green chemistry. The previous
powdered B12-TiO2 system requires filtration during the work-
up procedure. During filtration, some powdered catalyst was
¹9
surface coverage of B12 was determined to be 2.5 © 10
mol cm¹2. From the SEM image, growth of a porous film
containing B12-TiO2 nanoparticles was clearly observed as
shown in Figure 2. The thickness of the TiO2 film was ca.
300 nm, which is controlled by changing the rate of the dip-
coating. Due to this porous structure, the substrate can access
the B12 catalytic center within the film.
To confirm this, axial ligation of the cobalt center of B12 was
monitored by UV-vis. As the hybrid glass plate was immersed
in an imidazole methanol solution, the spectrum changed to one
with absorption maxima at 359, 465, 518, and 554 nm as shown
in Figure 3. This spectrum was identified as the imidazole-
coordinated B12 complex.8 Therefore, it is obvious that the
substrate molecules could access the B12 catalytic center, and
all of the immobilized B12 is expected to participate in the
catalytic reaction.
A catalytic reaction using the B12-TiO2 glass plate was
carried out as shown in Table 1. The diethyl 2-bromomethyl-2-
phenylmalonate (1) substrate was converted to products, and
the phenyl-migrated product 2 was formed along with the
formation of the simply reduced product 3 in ethanol as
expressed by eq 1. The reaction did not proceed when we used
the B12-unmodified TiO2 or in the dark as shown by Entries 4
³ Present address: Center of Advanced Instrumental Analysis,
Kyushu University, Fukuoka 819-0395
Published on the web January 29, 2010; doi:10.1246/bcsj.20090234

H. Shimakoshi et al.
Bull. Chem. Soc. Jpn. Vol. 83, No. 2 (2010)
171
O
O
O
Ph
H2C
Br
Ph
OEt
OEt
H
OEt
OEt
OEt
OEt
C
C
ð1Þ
+
C
Ph
C
H3C
in EtOH
O
H2
O
O
1
2
3
B12-TiO2 layer
Table 1. 1,2-Migration of Phenyl Group Catalyzed by
B12-TiO2 Systema)
Products (Yieldb)/%)
Entry Catalyst
Conversionb)/%
2
3
Glass plate
1
2
3
4
B12-TiO2
B12-TiO2
B12-TiO2
59
56
trace
trace
7
47
9
®
®
300 nm
c)
d)
33
®
®
e)
TiO2
Figure 2. Cross-sectional SEM photograph of the B12-TiO2
a) Conditions: [substrate] = 3.0 © 10¹3 M (3.0 © 10¹5 mol),
catalyst (B12-TiO2 glass): 2.5 © 5.5 cm2 (B12, 6.9 © 10¹8 mol),
solvent: C2H5OH (10 mL) under N2 at room temperature,
reaction time: 10 h. b) Conversions were estimated by the
recovery of the substrate. Yields were based on the initial con-
centration of the substrate. c) Solvent, PhCN, triethanolamine
(66.7 mg, 4.5 © 10¹4 mol, 45 mM) was used as a sacrificial
reagent. d) In the dark. e) Unmodified TiO2 glass plate was
used.
¹1
film at a 50 mm min withdrawing speed for the dip
coating.
(b)
NH
NH
0.3
N
OH2
CoIII
CN
N
CoIII
CN
Abs.
0.2
TiO2
TiO2
Cl
Cl
H
H
Cl
H
Cl
Cl
Cl
Cl
H
H
+
+
(2)
(a)
in MeOH
Cl
Cl
Cl
Cl
0.1
PCE
TCE
DCE (Z )
DCE (E )
Table 2. Dechlorination of PCE Catalyzed by B12-TiO2
0
Systema)
350 400 450 500 550 600 650 700
Wavelength / nm
Products (Yieldb)/%)
Entry Catalyst
Conversionb)/%
TCE 1,2-DCE (E/Z)
Figure 3. UV-vis spectral change in the B12-TiO2 glass
plate (a) before and (b) after immersion in imidazole
solution.
1
2
3
B12-TiO2
B12-TiO2
TiO2
59
3
trace
43
trace
®
1/1
®
c)
d)
®
and 3 in Table 1, respectively. It was noteworthy that the work-
up procedure was significantly simplified in the present system
though the conversion decreased to 59% as compared to the
powdered system. As for the powdered B12-TiO2 system,
the conversion was 95% under similar conditions.6b In the
present system, the catalyst immobilized on a glass plate
was easily separated from the product. Furthermore, B12-TiO2
was retained on the glass plate after the reaction, which was
confirmed by SEM.
The selectivity of the products was controlled by the
solvent.6b When the reaction was carried out in a less hydrogen
radical donating solvent, the yield of the phenyl-migrated
product 2 increased to 33% as shown by Entry 2 in Table 1
since PhCN has a strong C-H bond.9
Dehalogenation of an organic chloride was also carried out
as shown in Table 2. Perchloroethylene (PCE) was converted to
trichloroethylene (TCE) during irradiation by UV light in
methanol as expressed by eq 2. As cobalamin derivatives (B12)
are involved in the enzymatic reduction of chlorinated organic
compounds by anaerobic bacteria,10 many studies of the
dechlorination of PCE were reported using cobalamin deriv-
atives as a catalyst.11 Among these studies, our system is more
a) Conditions: [PCE] = 1.0 © 10¹4 M (1.5 © 10¹6 mol), cata-
lyst (B12-TiO2 glass): 2.5 © 2.4 cm2 (B12, 3.0 © 10¹8 mol),
solvent: CH3OH (15 mL) under N2 at room temperature,
reaction time: 10 h. b) Conversions were estimated by the
recovery of the substrate. Yields were based on the initial
concentration of the substrate. c) In the dark. d) B12-
unmodified TiO2 glass plate was used.
convenient and green since the catalyst was activated by simple
light irradiation and was easily separated after the reaction.
In conclusion, the heterogeneous B12-TiO2 hybrid catalyst
immobilized on a glass plate was prepared which was inspired
from the natural enzyme. The hybrid catalyst showed a high
reactivity for molecular transformation under mild conditions.
Therefore, the present system would be readily applicable for
the design of an eco-friendly catalyst.
Experimental
Apparatus. The NMR spectra were recorded with a Bruker
Avance 500 spectrometer at the Center of Advanced Instrumental
Analysis of Kyushu University, and the chemical shifts (in ppm)
were referenced relative to the residual protic solvent peak. The

172
Bull. Chem. Soc. Jpn. Vol. 83, No. 2 (2010)
© 2010 The Chemical Society of Japan
GC-mass spectra were obtained using a Shimadzu GCMS-
QP5050A equipped with a J&W Scientific DB-1 column (length
30 m; ID 0.25 mm, film 0.25 ¯m). Volatile organic compounds
(PCE, TCE, and DCE) were analyzed with a Shimadzu GCMS-
QP2010SPG equipped with a Perkin-Elmer Turbo Matrix HS16
using a J&W Scientific DB-624 column (length 60 m; ID 0.32 mm,
film 1.80 ¯m). The UV-vis absorption spectra were measured with
a Hitachi U-3300 spectrophotometer at room temperature. Scan-
ning electron micrographs (SEMs) were recorded on a Hitachi
S-5000 (HV = 25 kV). The X-ray photoelectron spectroscopy
(XPS) experiments were performed with a Physical Electronics
XPS 5800. The X-ray diffraction (XRD) analyses were measured
with a MacScience Micro-focus X-ray M18XHF diffractometer
(Cu K¡, - = 1.54056 ¡). Dip coatings were performed by an
Eintesla MD-408 micro dip-coater.
Chemicals. All solvents and chemicals used in the syntheses
were of reagent grade, and were used without further purification.
A corrinoid compound (B12), cyanoaquacobyrinic acid ([(CN)-
(H2O)Cob(III)7COOH]Cl), was synthesized using a reported
method.6a The titanium dioxide sol solution (TS-S4110, anatase)
was kindly supplied by Sumitomo Chemical. The diethyl 2-
bromomethyl-2-phenylmalonate (1) substrate and authentic sample
of diethyl 2-methyl-2-phenylmalonate (3) were synthesized from
diethyl phenylmalonate.6b The phenyl-migrated product, diethyl
benzylmalonate (2), was purchased from Aldrich. Perchloroeth-
ylene (PCE) was purchased from GL Science as a methanol
solution (5000 ¯g mL¹1).
References
Recoverable catalysts and reagents: Chem. Rev. 2002, 102,
Isuue 10.
1
2
a) Vitamin B12 and B12-Protein, ed. by B. Kräutler, D.
Arigoni, B. T. Golding, Wiley-VCH, Weinheim 1998. b) R.
Banerjee, Chem. Rev. 2003, 103, 2083. c) T. Toraya, Chem. Rev.
2003, 103, 2095. d) K. L. Brown, Chem. Rev. 2005, 105, 2075.
3
a) A. Ruhe, L. Walder, R. Scheffold, Helv. Chim. Acta
1985, 68, 1301. b) Y. Murakami, Y. Hisaeda, T. Ozaki, Y. Matsuda,
J. Chem. Soc., Chem. Commun. 1989, 1094. c) D.-L. Zhou, C. K.
Njue, J. F. Rusling, J. Am. Chem. Soc. 1999, 121, 2909. d) K.
Ariga, K. Tanaka, K. Katagiri, J. Kikuchi, H. Shimakoshi, E.
Ohshima, Y. Hisaeda, Phys. Chem. Chem. Phys. 2001, 3, 3442.
e) D. Mimica, F. Bedioui, J. H. Zagal, Electrochim. Acta 2002, 48,
323. f) A. S. Viana, M. Kalaji, L. M. Abrantes, Electrochim. Acta
2002, 47, 1587. g) H. Shimakoshi, A. Nakazato, M. Tokunaga, K.
Katagiri, K. Ariga, J. Kikuchi, Y. Hisaeda, Dalton Trans. 2003,
2308. h) H. Shimakoshi, M. Tokunaga, K. Kuroiwa, N. Kimizuka,
Y. Hisaeda, Chem. Commun. 2004, 50. i) R. Fraga, J. P. Correia, R.
Keese, L. M. Abrantes, Electrochim. Acta 2005, 50, 1653.
4
a) J. F. Rusling, C. L. Miaw, E. C. Couture, Inorg. Chem.
1990, 29, 2025. b) H. Shimakoshi, M. Tokunaga, Y. Hisaeda,
Dalton Trans. 2004, 878. c) H. Shimakoshi, Y. Maeyama, T.
Kaieda, T. Matsuo, E. Matsui, Y. Naruta, Y. Hisaeda, Bull. Chem.
Soc. Jpn. 2005, 78, 859. d) Md. A. Jabbar, H. Shimakoshi, Y.
Hisaeda, Chem. Commun. 2007, 1653.
5
a) R. Sheffold, G. Rytz, L. Walden, in Modern Synthetic
Preparations of B12-TiO2 Glass Plate. The TiO2 sol solution
(TS-S4110) was deposited on a freshly cleaned slide glass
substrate (Matsunami Glass Industries) by dip coating at with-
drawing speeds of 50 mm min¹1. The TiO2 film formed on the
substrate was dried for 24 h at room temperature. The obtained
glass plate coated with the TiO2 film was immersed in a 1 mM
solution of cyanoaquacobyrinic acid (B12) in H2O for 30 min. The
B12 content on the glass plate was determined by UV-vis; B12
content: 2.5 © 10¹9 mol cm¹2. UV-vis -/nm: 352, 455, 498, 529.
XPS E/eV: 780.4 (Co2p), 458.6 (Ti2p), 398.8 eV (N1s). XRD
2ª/°: 25.2, 37.8, 48.0, 53.8, 55.0, 62.6 (anatase).
Methods, ed. by R. Sheffold, Otto Salle, Frankfurt, 1983, pp. 355-
440. b) H. Shimakoshi, A. Nakazato, T. Hayashi, Y. Tachi, Y.
Naruta, Y. Hisaeda, J. Electroanal. Chem. 2001, 507, 170. c) J.
Shey, C. M. McGinley, K. M. McCauley, A. S. Dearth, B. T.
Young, W. A. van der Donk, J. Org. Chem. 2002, 67, 837.
6
a) H. Shimakoshi, E. Sakumori, K. Kaneko, Y. Hisaeda,
Chem. Lett. 2009, 38, 468. b) H. Shimakoshi, M. Abiru, S. Izumi,
Y. Hisaeda, Chem. Commun. 2009, 6427. c) Y. Hisaeda, Bull. Jpn.
Soc. Coord. Chem. 2009, 54, 10.
7
A. Fujishima, T. N. Rao, D. A. Tryk, J. Photochem.
Photobiol., C 2000, 1, 1.
Catalytic Reaction of B12-TiO2 Glass Plate (General Proce-
dure). The B12-TiO2 glass plate (area: 2.5 © 5.5 cm2 © 2 (both
sides), B12: 6.9 © 10¹8 mol) was immersed in a 10 mL ethanol
solution of a diethyl 2-bromomethyl-2-phenylmalonate (3.0 ©
10¹5 mol, 3.0 mM) under nitrogen gas atmosphere. The solution
was stirred at room temperature under irradiation with 365 nm UV
8
M. S. A. Hamza, J. M. Pratt, J. Chem. Soc., Dalton Trans.
1994, 1373.
9
Y.-R. Luo, Handbook of Bond Dissociation Energies in
Organic Compounds, CRC Press, Boca Raton, 2003.
10 a) C. Holliger, G. Wohlfarth, G. Diekert, FEMS Microbiol.
Rev. 1998, 22, 383. b) B. Kräutler, W. Fieber, S. Ostermann, M.
Fasching, K.-H. Ongania, K. Gruber, C. Kratky, C. Mikl, A.
Siebert, G. Diekert, Helv. Chim. Acta 2003, 86, 3698.
¹2
light (1.76 mW cm at 12 cm distance). The product was directly
analyzed by GC-MS. Diphenyl was used as the internal standard.
11 a) C. J. Gantzer, L. P. Wackett, Environ. Sci. Technol. 1991,
25, 715. b) D. R. Burris, C. A. Delcomyn, M. H. Smith, A. L.
Roberts, Environ. Sci. Technol. 1996, 30, 3047. c) G. Glod, W.
Angst, C. Holliger, R. P. Schwarzenbach, Environ. Sci. Technol.
1996, 31, 253. d) J. Shey, W. A. van der Donk, J. Am. Chem. Soc.
2000, 122, 12403. e) K. M. McCauley, D. A. Pratt, S. R. Wilson, J.
Shey, T. J. Burkey, W. A. van der Donk, J. Am. Chem. Soc. 2005,
127, 1126. f) C. Costentin, M. Robert, J.-M. Savéant, J. Am. Chem.
Soc. 2005, 127, 12154. g) G. Diekert, D. Gugova, B. Limoges, M.
Robert, J.-M. Savéant, J. Am. Chem. Soc. 2005, 127, 13583.
This study was partially supported by a Grant-in-Aid for
Scientific Research on Priority Areas (452 and 460) and Global
COE Program “Science for Future Molecular Systems” from the
Ministry of Education, Culture, Sports, Science and Technology
(MEXT) of Japan, an Industrial Technology Research Grant
Program in 2005 from New Energy and Industrial Technology
Development Organization (NEDO) of Japan, and a Grant-in-
Aid for Scientific Research (A) (No. 21245016) from the Japan
Society for the Promotion of Science (JSPS).