Visible light singlet oxygen production with tetra(4-carboxyphenyl) porphyrin/SiO2

Article abstract of DOI:10.1016/j.jphotochem.2013.03.005

The production of singlet oxygen with tetra(4-carboxyphenyl)porphyrin adsorbed on SiO₂ irradiated with visible light (λ > 500 nm) was evidenced by EPR spectra of TEMPO formed by oxidation of 2,2,6,6-tetramethyl-4-piperidone(TEMP) with ¹O₂. The formation of singlet oxygen was also evidenced by the formation of anthraquinone and oxanthrone as oxidation products of anthracene with ¹O ₂. The absence of the EPR DMPO-O₂^- signal evidenced that superoxide anion was not present. No other oxygen radicals were detected. TCPP and TCPP/SiO₂ were characterized with UV-vis, UV-vis diffuse reflectance and FT-IR spectroscopy.

Full text of DOI:10.1016/j.jphotochem.2013.03.005

Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
Contents lists available at SciVerse ScienceDirect
Journal of Photochemistry and Photobiology A:
Chemistry
journal homepage: www.elsevier.com/locate/jphotochem
Visible light singlet oxygen production with
tetra(4-carboxyphenyl)porphyrin/SiO2
a,b,c,∗
b
c
c
Carlos E. Diaz-Uribed
, Martha C. Daza , Edgar A. Páez-Mozo , Fernando Martínez O. ,
d
Carmen L.B. Guedes , Eduardo Di Mauro
Grupo de Investigación Fisicoquímica Aplicada y Estudios Ambientales, Laboratorio de Fotoquímica y Fotobiología, Programa de Química,
a
Facultad de Ciencias Básicas, Universidad del Atlántico, Kilómetro 7 Vía Puerto Colombia, Barranquilla, Colombia
b
Grupo de Bioquímica Teórica, Universidad Industrial de Santander, Bucaramanga, Colombia
Centro de Investigaciones en Catálisis, Universidad Industrial de Santander, Bucaramanga, Colombia
Laboratório de Fluorescência e Ressonância Paramagnética Eletrônica (LAFLURPE), Universidade Estadual de Londrina, Londrina, PR, Brazil
c
d
a r t i c l e i n f o
a b s t r a c t
Article history:
The production of singlet oxygen with tetra(4-carboxyphenyl)porphyrin adsorbed on SiO2 irradiated
Received 16 September 2012
Received in revised form 25 February 2013
Accepted 12 March 2013
with visible light (ꢀ > 500 nm) was evidenced by EPR spectra of TEMPO formed by oxidation of 2,2,6,6-
1
tetramethyl-4-piperidone(TEMP) with O2. The formation of singlet oxygen was also evidenced by the
1
formation of anthraquinone and oxanthrone as oxidation products of anthracene with O2. The absence
Available online 18 March 2013
•
−
of the EPR DMPO-O2 signal evidenced that superoxide anion was not present. No other oxygen radicals
were detected. TCPP and TCPP/SiO2 were characterized with UV–vis, UV–vis diffuse reflectance and FT-IR
spectroscopy.
Keywords:
Porphyrin
Silica
©
2013 Elsevier B.V. All rights reserved.
Singlet oxygen
TEMPO
1
. Introduction
Clean oxidation reactions promoted by singlet oxygen ( O )
due to the interaction between the irradiated photosensitizer and
molecular oxygen [11].
1
Widely used sensitizers such as Rose Bengal (absorption band
500–600 nm) with 1O2 quantum yield ˚ꢁ = 0.7, Methylene blue
(absorption band 550–700 nm) with ˚ꢁ = 0.5 in organic solvents
[3,12] undergo photodegradation under extensive irradiation [13].
2
are very attractive in environmental remediation processes [1].
In order to study 1O2 oxidation reactions it is necessary to selec-
tively generate this reactive species. However with photochemical
methods the superoxide anion (O2 ) may also be produced [2,3]
and chemical methods with hydrogen peroxide-sodium molybdate
hydroxyl radicals are also generated [4,5].
Recently porphyrins and their analogs have been proposed for
environment-friendly singlet oxygen generation. Porphyrins play
important biological roles and are not cytotoxic, which is very
important in medical applications such as blood sterilization and
photodynamic therapy (PDT) [6,7].
•
−
1
Phenalenone has a very high O quantum yield ˚ = 1 but absorbs
2
ꢁ
in the UV region (absorption band 250–425 nm) [14]. Monomeric
tetra(4-carboxyphenyl)porphyrin (TCPP) (˚ꢁ = 0.7–0.9) [15] and
many other photosensitizers like the chlorins [16] and phthalo-
cyanines [17] are very suitable and promising for biological
applications, produces singlet oxygen with high yield and absorbs
in the visible region, which makes it suitable for biological applica-
tions.
Porphyrins may produce either superoxide anion radicals (type
I process) or singlet oxygen (type II process). In presence of visi-
ble light, porphyrins can efficiently produce singlet oxygen [8–10].
In PDT there is considerable evidence that the type II photo-
oxygenation process predominates in the induction of cell damage
In solution porphyrins tend to form aggregates without the
formation of covalent linkages. Aggregation affects their physico-
chemical and photophysical properties [18,19], lowers their 1O2
yield [10] and decreases their photodynamic effect. Binding of por-
phyrin sensitizers to biopolymers and other carriers in order to
avoid aggregation has been subject of recent studies [20,21]. There
is increasing interest in using SiO2 as support of photosensitizers.
Since SiO2 can be prepared with large surface area and modulated
porosity, it allows the attachment of a large number of photosensi-
tizer molecules to its surface resulting in favorable 1O2 production
[22].
∗ Corresponding author. Tel.: +57 5599484.
E-mail addresses: carlosdiaz@mail.uniatlantico.edu.co, carloslip5@hotmail.com
(
C.E. Diaz-Uribe).
1
010-6030/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jphotochem.2013.03.005

4
8
C.E. Diaz-Uribe et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
2
. Materials and methods
+ 1
o
O2
o
2.1. Materials
Scheme 1. Reaction singlet oxygen with anthracene.
Solvents were purchased from J.T. Baker. Anthracene and
sodium azide were acquired from Merck. 2,2,6,6-tetramethyl-4-
piperidone (TEMP) and 5,5-dimethyl-l-pyrroline-N-oxide (DMPO)
were manufactured by Sigma–Aldrich. All reactives were of analyt-
ical grade.
The interaction of porphyrin molecules with silanol groups
Si OH) through hydrogen bonds promotes the non-radiative
(
decay of porphyrins. The covalent bond between porphyrin
molecules and silica walls probably hinders inter system crossing
from the singlet excited state of the porphyrin to the triplet state,
which is a crucial step for photochemical activation of dioxygen
2
.2. Spectroscopic measurements
The UV–vis spectrum of the TCPP in ethanol was measured using
a Hewlett-Packard 8453 spectrophotometer. The UV–vis diffuse
reflectance absorption spectrum of the solid TCPP/SiO2 was mea-
sured using a Lambda 4 PerkinElmer spectrophotometer equipped
with an integrating sphere. FT-IR spectra (KBr) were recorded on
a Bruker Tensor 27 spectrometer. Specific surface area (BET) and
pore diameter distribution of the catalysts were obtained from N2
adsorption–desorption isotherms at 77 K using a Quantachrome
Nova 1200.
[
23,24].
The singlet oxygen photoproduction by a sensitizer could be
evidenced by Electron Paramagnetic Resonance (EPR). Chemical
trapping by polycyclic aromatic hydrocarbons is specific for sin-
glet oxygen detection [25]. A very characteristic reaction of singlet
oxygen is the [4+2] cycloaddition to conjugated cyclic dienes and
polycyclic aromatic hydrocarbons such as anthracene. Anthracene
traps reversibly singlet oxygen, see Scheme 1. The formation of
radicals in the reaction medium [26,27] can be detected by the
formation of 9-hydroxy and 9-ketoanthracene as a product of the
reaction between anthracene and oxygen radicals.
2.3. Synthesis of porphyrin
The carboxyphenylporphyrin (TCPP) was synthesized according
Singlet oxygen reacts with 2,2,6,6-tetramethyl-4-piperidone-
N (TEMP) to produce 2,2,6,6-tetramethyl-4-piperidone-N-oxyl
radical (TEMPO) which can be observed by EPR spectroscopy.
to methods described in the literature [30,31]. Pyrrole (30 mmol)
was added to a mixture of 4-carboxybenzaldehyde (30 mmol), pro-
pionic acid (105 mL) and nitrobenzene (45 mL). The mixture was
•
−
Superoxide anion does not react with anthracene. O2
may be
◦
heated 1 h at 120 C. After cooling and solvent removal under
detected by EPR spin trapping using 5,5-dimethyl-1-pyrroline-N-
oxide (DMPO) [28].
In the present work, experimental evidences of the formation
of singlet oxygen with tetra(4-carboxyphenyl)porphyrin (Fig. 1)
adsorbed on SiO2 under visible light as only photoproducts are
vacuum, the porphyrin was dissolved in 250 mL of 0.1 M NaOH.
The porphyrin was then precipitated with 1 M HCl solution, dis-
solved in ethanol and recrystallized by solvent evaporation. FT-IR
−
1
(KBr, cm ): 1605 s [C C]; 1110 s, 1006 s, 1307 m, 1311 m, 1531 m,
1
485 m [pyrrole ring]; 1699 s [C O]; 1404 m, 1268 s [C O] [32].
provided using chemical trapping and TEMPO EPR spectroscopy
1
[
29]. The formation of O2 was evidenced by the production of
2
.4. Synthesis of SiO2
anthraquinone and oxanthrone which are formed by the reaction
of anthracene with 1O . The absence of the EPR DMPO-O2 signal
•−
2
SiO was prepared following the reported procedure [33]. 10 mL
evidenced that superoxide anion was not present. No other oxygen
radicals were detected.
2
tetraethoxysilane (TEOS) were refluxed 4 h in 100 mL of a solu-
tion of water/absolute ethanol (1/8 M) at pH = 3 (adjusted with
HNO ) at 60 C with magnetic stirring. Absolute ethanol was added
◦
3
◦
(10 mL), and the temperature was increased to 76 C the mixture
was stirred under reflux for 24 h. The solvent was rotoevaporated
◦
and the remaining solid heated in air for 4 h at 450 C.
2.5. Adsorption of TCPP on SiO2
8
.3 mmol of SiO2 were suspended in 250 mL of 0.4 mM TCPP
solution (pH > 10) during 1 h. The pH was adjusted to 3.0 with 0.1 M
H SO , and the solid was filtered, washed with distilled water and
2
4
dried at room temperature [34]. The total amount of TCPP adsorbed
on SiO was quantified with UV–vis spectroscopy after treating the
2
sample (TCPP/SiO ) first with NaOH 0.1 M and then with ethanol.
2
We have no evidence of the distribution of TCPP either on the sur-
face or inside the pores.
2.6. EPR experiments
(a) TCPP and TCPP/SiO2 were characterized by EPR spectroscopy.
The solid samples were measured directly in quartz tubes.
(
b) EPR-TEMP method to study singlet oxygen formation. Pho-
togenerated singlet oxygen reacts with TEMP leading to the
paramagnetic TEMPO, which has a characteristic three-line EPR
spectrum [29]. Singlet oxygen was detected in a suspension of
0
.12 mmol of the photosensitizer, in a solution of TEMP (10 mM)
Fig. 1. Representation of porphyrin structure.
in toluene. Photoreactions were carried out in an immersion

C.E. Diaz-Uribe et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
49
well-type quartz photoreactor system supplied by Ace Glass-
880. The solution was irradiated with visible light (halogen
lamp of 100 W) filtered with a potassium dichromate solution
1 M) circulating in the immersion well to remove wavelengths
500 nm. The samples in quartz tubes were measured under
normal conditions, with 100 kHz magnetic field modulation,
0 mW microwave power and 5 G modulation amplitude in a
7
(
<
1
JEOL (JES-PE-3X) spectrometer.
(
c) Study of radical formation by the EPR-DMPO method. The
measurement of the spin trapping EPR by DMPO was used
to determine the generation of superoxide anion radical by
TCPP/SiO . The formation of superoxide anion radical was mea-
2
sured in a suspension of 0.01 g of TCPP/SiO2 in a solution of
DMPO (50 mM) in DMSO. Photoreactions were carried out in
an immersion well-type quartz photoreactor system supplied
by Ace Glass-7880. The solution was irradiated with visible
light (halogen lamp of 100 W) filtered with a potassium dichro-
mate solution (1 M) circulating in the immersion well to remove
wavelengths 500 nm. The samples were transferred immedi-
ately to 100 ␮L quartz capillaries and were measured under
normal conditions, with 100 kHz magnetic field modulation,
−5
Fig. 2. UV–vis spectra of TCPP in ethanol solution (2.5 × 10 M, thick line) and TCPP
adsorbed on SiO (0.1 g, thin line).
2
electronic structure of the ꢂ system of porphyrin, as was found in
other previous studies [23,24].
An average pore diameter of 19.9 A˚ and a specific surface
1
0 mW microwave power and 5 G modulation amplitude in a
2
−1
of SiO2 were obtained from N2 adsorption-
area of 567 m g
JEOL (JES-PE-3X) spectrometer. Spectra were simulated using
the BRUKER WINEPR SimFonia Version 1.25 software to deter-
desorption isotherms at 77 K (BET method). The hysteresis of the
•
−
mine the spin Hamiltonian parameters of DMPO–O
.
2
2
+
(
d) A MgO:Mn (g = 1.981 of the fourth line) reference standard
sample (g and intensity marker) was maintained in the EPR
cavity of the JEOL spectrometer, the data was recorded simul-
taneously with the sample.
2.7. Singlet oxygen chemical trapping by anthracene
The experiments were performedin oxygen atmosphere,
according to the following procedure: 0.12 mmol of the TCPP or
TCPP/SiO2 was added to 10 mL of a solution of anthracene dis-
solved in dichloromethane (0.2 mM) in photoreactor system in
a batch photo-reactor with a 100 W OSRAM halogen immersion
lamp. The light was filtered through a 1 M potassium dichromate
solution to remove wavelengths <500 nm. The incident photon flow
per unit volume Io was determined by chemical actinometry [35],
using 0.01 M Reinecke salt solution.Irradiation of the suspension
was started after 1 h in the dark (with stirring). Sample aliquots
of 0.1 mL were taken during irradiation, filtered and measured by
UV–vis spectrophotometry at ꢀmax = 375 nm.A sample of the reac-
tion mixture was analyzed by GC–MS in a 5890 Hewlett Packard gas
chromatograph, with a 5972 mass selective detector and a HP5-MS
(
30 m long and 0.25 mm internal diameter) column and with He as
the carrier gas (1 mL/min). 1 ␮L sample aliquots were injected with
split (1:30). The following temperature program was applied: heat-
◦
◦
◦
ing at 200 C for 5 min, heating to 300 C with a rate of 10 C/min.
This temperature was maintained for 15 min. Detector conditions:
7
0 eV, electronic impact, 35–400 m/z mass range, 200 V EM voltage
◦
(
A-tune), 20 Hz Sweep Frequency at 230 C.
3
. Results and discussion
3.1. Characterization of TCPP and TCPP/SiO2
The formation of TCPP was evidenced by the presence of the
typical Soret band (419 nm) and four Q bands (514, 548, 588 and
45 nm) in the UV–vis absorption spectra in ethanol (Fig. 2) [36].
6
The absorption spectrum of TCPP adsorbed on SiO2 exhibited a
red shift with respect to the ethanol solution. This is probably
due to the formation of hydrogen bonds between the carboxyl
groups of the porphyrin and SiOH on the surface, which affects the
Fig. 3. EPR spectra at room temperature of free TCPP (a); and TCPP adsorbed on
SiO2 (b). MgO:Mn was used as g marker and intensity standard. The spectroscopic
g factor of TCPP is 2.003 (free) and 2.005 (adsorbed).
2+

5
0
C.E. Diaz-Uribe et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
O
O
+
H
1
+
O
+ H O
2
2
N
H
N
O
TEM P
TEM PO
Scheme 2. Oxidation of TEMP by singlet oxygen.
Fig. 5. TEMPO’s adduct generation as function of irradiation time.
parameters of TEMPO were determined using the BRUKER WINEPR
SimFonia Version 1.25 software as aN = 15.5 Gauss (hyperfine cou-
pling constant) and g = 2.006 (spectroscopic factor). The g factor and
the hyperfine coupling constant of the EPR signal are in very good
agreement with the experimental values of TEMPO [40].
Fig. 4. EPR spectra at room temperature of TEMPO after 2 min of irradiation: (a)
TCPP; (b) TCPP/SiO2. MgO:Mn was used as g marker and intensity standard.
When the TCPP/SiO2 system was irradiated with visible light in
the presence of DMPO no DMPO-O2 adduct was detected. This
2+
•−
can be interpreted as follows:
adsorption-desorption isotherms of SiO2 is of Langmuir Type I,
which is characteristic for microporous solids [37]. The amount of
TCPP adsorbed on SiO2 is 0.254 mmol TCPP/g SiO2.
(1) The electron transfer from the TCPP in its photo-excited state
(first singlet or triplet excited state) to the SiO2 or TiO2 con-
duction band (CB) (type I photodynamic reaction) depends on
its energy difference. Fig. 7 shows the relative energy levels of
The EPR spectra of TCPP and TCPP/SiO2 exhibited only one line
(
Fig. 3a). The EPR signals of porphyrins are generated by the inter-
action of the delocalized ꢂ electrons of the porphyrin with the
magnetic field [38]. The free radicals formed are stable and were
detected by EPR directly at room temperature. The EPR signal inten-
sity of the TCPP/SiO2 was lower than that of TCPP (Fig. 3b), due to
the smaller amount of TCPP in the TCPP/SiO2 sample.
SiO , TiO2 and the adsorbed TCPP. The relative position of the
energy levels suggests that the electron transfer process from
the excited state of the porphyrin to the TiO2 CB is favorable
2
3.2. EPR-TEMP detection of singlet oxygen
The EPR spin trapping technique with TEMP as spin trapper
was used to determine the singlet oxygen photo-generationat
room temperature from TCPP and TCPP/SiO . The characteristic
2
EPR spectrum of TEMPO consists of three equally intense lines [29]
(
(
Fig. 4). TEMPO is formed by oxidation of TEMP with singlet oxygen
Scheme 2). The TEMPO signal was reduced (∼50%) for TCPP/SiO2
compared to free TCPP in liquid phase, probably due to lower oxy-
gen diffusion in the silica matrix. Similar results were obtained by
Wang et al. [39].
The intensity of the EPR signal of TEMPO with TCPP/SiO2
increases with irradiation time (Fig. 5). No signal was observed in
the dark. Equilibrium is reached above 100 s.
Fig. 6 shows the TEMPO adduct EPR experimental (continuous
line) and simulated (dotted line) spectra. The spin Hamiltonian
Fig. 6. Experimental EPR spectrum (continuous line) and its simulation (dotted line).

C.E. Diaz-Uribe et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
51
Fig. 7. Diagram illustrating the energetic of sensitation of TiO2 and SiO2 particles by TCPP.
[
41–43], whereas it is not favorable to the SiO CB consequently
O
2
in presence of SiO , superoxide anion is not formed.
2
(
2) Superoxide anion may be formed via electron transfer from the
TCPP excited state to O , but the absence of signals from DMPO-
2
•
−
O
O
O2
adducts in the EPR spectra indicates that the presence of
1
+ O2
o
o
superoxide anion generation could be discarded.
3.3. Singlet oxygen chemical trapping by anthracene
OH
Singlet oxygen generation by tetra(4-carboxyphenyl)porphyrin
adsorbed on SiO2 is evidenced by chemical trapping of 1O2
Scheme 3. Decomposition of the endoperoxide intermediary.
with anthracene. Fig. 8 shows the reduction of the anthracene
absorbance at 375 nm due to the formation of the endoperoxide by
a [4 + 2] cycloaddition of anthracene with singlet oxygen according
to Scheme 3. Addition of azide (0.2 mM) (a strong singlet oxygen
quencher [44]) inhibited the oxidation of anthracene with singlet
oxygen during the irradiation procedure, and no reactions were
further observed in the dark.
Anthraquinone and oxanthrone produced by the decomposi-
tion of the endoperoxide intermediary were identified as the only
oxidation products of anthracene (Scheme 3). The absence of the
•
−
DMPO-O2 and DMPO-OH adducts (not detected by EPR) suggest
the absence of radicals.
UV–vis spectroscopy does not show presence of TCPP in the
solution indicating that the porphyrin has not leached into the
solution under the reaction conditions. The GC–MS indicates the
presence of anthracene (reagent) and anthraquinone (oxidation
product).
4. Conclusions
In the present work, experimental evidences of the formation
of singlet oxygen with TCPP/SiO2 under visible light as only pho-
toproduct are provided using chemical trapping and TEMPO EPR
spectroscopy. The formation of 1O2 was evidenced by the produc-
tion of anthraquinone and oxanthrone which are formed by the
1
reaction of anthracene with O . The absence of the EPR DMPO-
2
•
−
O2
signal shows that superoxide anion was not present. No other
Fig. 8. UV–vis spectra of anthracene as a function of irradiation time with TCPP as
photosensitizer.
oxygen radicals were detected.

5
2
C.E. Diaz-Uribe et al. / Journal of Photochemistry and Photobiology A: Chemistry 259 (2013) 47–52
Inorganic semiconductors, such as silicon dioxide, with bound
photosensitizers are becoming increasingly important for appli-
cations in photocatalysis, dye sensitized solar cells, and many
[18] W. Xu, H. Guo, D.L. Akins, Aggregation of tetrakis(p-sulfonatophenyl) porphyrin
within modified mesoporous MCM-41, Journal of Physical Chemistry B 105
2001) 1543–1546.
(
[
19] R. Giovannetti, L. Alibabaei, L. Petetta, Aggregation behaviour of a tetracar-
boxylic porphyrin in aqueous solution, Journal of Photochemistry and
Photobiology A: Chemistry 211 (2010) 108–114.
other areas. This paper reports
a system where tetrakis(4-
carboxyphenyl)porphyin (TCPP) is absorbed onto porous silica
particles. Upon photolysis in the presence of oxygen strong evi-
dence is provided that the only detectable photosensitization
process involves formation of singlet oxygen. There is no com-
peting superoxide formation. This is demonstrated by reaction of
reactive oxygen species with spin probes and also by identification
of the chemical products from reaction with anthracene. Although
there have been other studies on TCCP bound to silica particles,
our results are new and provide information on photosensitization
pathways in the presence of oxygen, which will be useful for people
working in the area of photocatalysis.
Tetra(4-carboxypenyl)porphyrin adsorbed on SiO2 with visible
light generates singlet oxygen and no other oxygen species, as was
evidenced by TEMPO EPR measurements and chemical trapping
with anthracene. It can be used as a pure single oxygen generation
system for biological applications.
[
20] K. Lang, J. Mosinger, D.M. Wagnerová, Photophysical properties of porphyrinoid
sensitizers non-covalently bound to host molecules; models for photodynamic
therapy, Coordination Chemistry Reviews 248 (2004) 321–350.
[21] J. Mosinger, M. Deumié, K. Lang, P. Kubát, D.M. Wagnerová, Supramolecular
sensitizer: complexation of meso-tetrakis(4-sulfonatophenyl)porphyrin with
2-hydroxypropyl-cyclodextrins, Journal of Photochemistry and Photobiology
A: Chemistry 130 (2000) 13–20.
[22] D. Bechet, P. Couleaud, C. Frochot, M.L. Viriot, F. Guillemin, M. Barberi-Heyob,
Nanoparticles as vehicles for delivery of photodynamic therapy agents, Trends
in Biotechnology 26 (2008) 612–621.
[
[
[
23] M. Trytek, M. Majdan, A. Lipke, J. Fiedurek, Sol–gel immobilization of octaethyl-
porphine and hematoporphyrin for biomimetic photooxidation of ␣-pinene,
Journal of Catalysis 286 (2012) 193–205.
24] W. Kim, J. Park, H.J. Jo, H. Kim, W. Choi, Visible light photocatalysts based on
homogeneous and heterogenized tin porphyrins, Journal of Physical Chemistry
C 112 (2008) 491–499.
25] J.M. Aubry, C. Pierlot, J. Rigaudy, R. Schmidt, Reversible binding of oxy-
gen to aromatic compounds, Accounts of Chemical Research 36 (2003)
668–675.
[26] D. Madhavan, K. Pitchumani, Photoreactions in clay media: singlet oxygen oxi-
dation of electron-rich substrates mediated by clay-bound dyes, Journal of
Photochemistry and Photobiology A: Chemistry 153 (2002) 205–208.
[
27] F. Goulay, C. Rebrion-Rowe, J.L. Le Garrec, S.D. Le Picard, A. Casona, B.R. Rowe,
The reaction of anthracene with OH radicals: an experimental study of the
kinetics between 58 and 470 K, Journal of Physical Chemistry 122 (2005)
104308(1)–104308(7).
Acknowledgments
Support from Universidad Industrial de Santander (5138
Project) is gratefully acknowledged. Carlos E. Diaz-Uribe thanks
COLCIENCIAS “Fondo apoyo a los Doctorados Nacionales” for the
financial support.
[28] J.R. Harbour, V. Chow, J.R. Bolton, An electron spin resonance study of the spin
adducts of OH and HO2 radicals with nitrone in ultraviolet photolysis of aque-
ous hydrogen peroxide solutions, Canadian Journal of Chemistry 52 (1974)
3549–3553.
[
29] Y. Lion, M. Delmelle, A. Van de Vorst, New method of detecting singlet oxygen
production, Nature 263 (1976) 442–443.
References
[30] A.D. Adler, F.R. Longo, J.D. Finarelli, J. Goldmacher, J. Assour, L. Korsakoff, A sim-
plified synthesis for meso-tetraphenylporphyrin, Journal of Organic Chemistry
3
2 (1967) 476.
[
[
[
1] M.C. De Rosa, R.J. Crutchley, Photosensitized singlet oxygen and its applications,
Coordination Chemistry Reviews 351 (2002) 233–234.
2] C.R. Lambert, I.E. Kochevar, Does rose Bengal triplet generate superoxide anion?
Journal of the American Chemical Society 118 (1996) 3297–3298.
3] J.P. Tardivo, A. Del Giglio, C. Santos de Oliveira, D. Santesso-Gabrielli, H. Couto-
Junqueira, D. Batista-Tada, D. Severino, R. Turchiello, M.S. Baptista, Methylene
blue in photodynamic therapy: from basic mechanisms to clinical applications,
Photodiagnosis and Photodynamic Therapy 2 (2005) 175–191.
[
31] M.A. Schiavon, L.S. Iwamoto, A.G. Ferreira, Y. Iamamoto, M.V.B. Zanoni, M.D.
Assis, Synthesis and characterization of a novel series of meso(nitrophenyl) and
meso(carboxyphenyl) substituted porphyrins, Journal of the Brazilian Chemical
Society 11 (2000) 458–466.
32] Q. Wang, W.M. Campbell, E.E. Bonfantani, K.W. Jolley, D.L. Officer, P.J. Walsh,
K. Gordon, R. Humphry-Baker, M.K. Nazeeruddin, M. Grätzel, Efficient light
harvesting by using green Zn-porphyrin-sensitized nanocrystalline TiO2 films,
Journal of Physical Chemistry B 109 (2005) 15397–15409.
33] T. López, A. López-Gaona, R. Gómez, Synthesis, characterization and activity of
Ru/SiO2 catalysts prepared by the sol–gel method, Journal of Non-Crystalline
Solids 110 (1989) 170–174.
34] Y. Cho, W. Choi, C.H. Lee, T. Hyeon, H.I. Lee, Visible light-induced degrada-
tion of carbontetrachloride on dye-sensitized TiO2, Environmental Science and
Technology 35 (2001) 966–970.
[
[
[
[
[
[
[
4] J.M. Aubry, Search for singlet oxygen in the decomposition of hydrogen per-
oxide by mineral compounds in aqueous solutions, Journal of the American
Chemical Society 107 (1985) 5844.
5] C.E. Diaz-Uribe, F. León, M.C. Daza, F. Martínez, Oxidación de antraceno
con oxígeno singulete generado químicamente por el sistema molibdato de
sodio/peróxido de hidrógeno, Revista Colombiana de Química 37 (2008) 45–53.
6] G. Rossi, R. Fedele, C. Comuzzi, D. Goi, Bactericidal activity characterization of
an expanded porphyrin on Gram-positive bacteria, Journal of Biotechnology
[
[
[
35] J.F. Cornet, A. Marty, J.B. Gros, Revised technique for the determination of mean
incident light fluxes on photobioreactor, Biotechnology Progress 13 (1997)
1
50 (2010) 438.
4
08–415.
7] F. Schmitt, N. Barry, L. Juillerat-Jeanneret, B. Therrien, Efficient photodynamic
therapy of cancer using chemotherapeutic porphyrin–ruthenium metalla-
cubes, Bioorganic and Medicinal Chemistry Letters 22 (2012) 178–180.
8] C. Tanielian, D. Wolff, Porphyrin-sensitized generation of singlet molecular
oxygen: comparison of steady-state and time-resolved methods, Journal of
Physical Chemistry 99 (1995) 9825–9830.
[
[
36] M. Gouterman, G.H. Wagnière, L.C. Snyder, Spectra of porphyrins: Part II. Four
orbital model, Journal of Molecular Spectroscopy 11 (1963) 108–127.
37] X. Li, Z. Li, Q. Xia, H. Xi, Effects of pore sizes of porous silica gels on desorp-
tion activation energy of water vapour, Applied Thermal Engineering 27 (2007)
8
69–876.
[
38] W. Zheng, N. Shan, L. Yu, X. Wang, UV–visible, fluorescence and EPR prop-
erties of porphyrins and metalloporphyrins, Dyes and Pigments 77 (2008)
9] R. Redmond, J. Gamlin, A compilation of singlet oxygen yields from biologically
relevant molecules, Photochemistry and Photobiology 70 (1999) 391–475.
1
53–157.
[
[
[
10] F. Ricchelli, Photophysical properties of porphyrins in biological membranes,
Journal of Photochemistry and Photobiology B: Biology 29 (1995) 109–118.
11] R. Bonnett, Photosensitizers of the porphyrin and phthalocyanine series for
photodynamic therapy, Chemical Society Reviews 24 (1995) 19–33.
12] J. Paczkowskit, D.C. Neckers, Polymer-based sensitizers for the formation of
singlet oxygen. New studies of polymeric derivatives of rose Bengal, Macro-
molecules 18 (1985) 1245–1253.
13] T.J. Dougherty, Photosensitizers: therapy and detection of malignant tumors,
Photochemistry and Photobiology 45 (1987) 879–889.
14] C. Flors, S. Nonell, Light and singlet oxygen in plant defense against pathogens:
phototoxic phenalenone phytoalexins, Accounts of Chemical Research 39
[
39] C. Wang, J. Li, G. Mele, G.M. Yang, F.-X. Zhang, L. Palmisano, G. Vasapollo,
Efficient degradation of 4-nitrophenol by using functionalized porphyrin-TiO2
photocatalysts under visible irradiation, Applied Catalysis B: Environmental 76
(
2007) 218–226.
[
40] C. Hadjur, A. Jeunet, P. Jardon, Photosensitization by hypericin: electron spin
resonance (ESR) evidence for the formation of singlet oxygen and superoxide
anion radicals in an in vitro model, Journal of Photochemistry and Photobiology
B: Biology 26 (1994) 67–74.
41] C. Diaz-Uribe, M.C. Daza, F. Martínez, E. Páez-Mozo, C. Guedes, E. Di
Mauro, Visible light superoxide radical anion generation by tetra(4-
carboxyphenyl)porphyrin/TiO2: EPR characterization, Journal of Photochem-
istry and Photobiology A: Chemistry 215 (2010) 172–178.
42] R. Renganathan, A. Kathiravan, Effect of anchoring group on the photosensiti-
zation of colloidal TiO2 nanoparticles with porphyrins, Journal of Colloid and
Interface Science 331 (2009) 401–407.
43] J. He, J. Zhao, H. Hidaka, N. Serpone, EPR characteristics of a dye/colloidal TiO2
system under visible light irradiation, Journal of the Chemical Society, Faraday
Transactions 94 (1998) 2375–2378.
[
[
[
(
2006) 293–300.
[
15] C.R. Lambert, E. Reddi, J.D. Spikes, M.A. Rodgers, G. Jori, The effects of porphyrin
structure and aggregation state on photosensitized processes in aqueous and
micellar media, Photochemistry and Photobiology 44 (1986) 595–601.
16] M. Pineiro, M. Pereira, A.M. Rocha-Gonsalves, L. Arnaut, S. Formosinho, Singlet
oxygen quantum yields from halogenated chlorins: potential new photo-
dynamic therapy agents, Journal of Photochemistry and Photobiology A:
Chemistry 138 (2001) 147–157.
[
[
[
[
44] C. Schweitzer, R. Schmidt, Physical mechanisms of generation and deactivation
of singlet oxygen, Chemical Reviews 103 (2003) 1685–1757.
[
17] K. Ishii, Functional singlet oxygen generators based on phthalocyanines, Coor-
dination Chemistry Reviews 256 (2012) 1556–1568.