Nanostructural catalyst: Metallophthalocyanine and carbon nano-onion with enhanced visible-light photocatalytic activity towards organic pollutants

Article abstract of DOI:10.1039/d0ra00896f

Metallophthalocyanine (MPc) and carbon nano-onion (CNO) derivatives were synthesized and characterized by using ultraviolet-visible spectroscopy, infrared and Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray powder diffraction. The unmodified CNOs and MPc-CNO derivatives were used as photocatalysts for rhodamine B (RhB) degradation under visible-light irradiation. The photocatalytic studies revealed that the MPc-CNO nanostructural materials simultaneously exhibited a high absorption capacity and an excellent visible-light-driven photocatalytic activity towards RhB. These nanostructures possess great potential for use as active photocatalysts for organic pollutant degradation.

Full text of DOI:10.1039/d0ra00896f

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Nanostructural catalyst: metallophthalocyanine
and carbon nano-onion with enhanced visible-light
photocatalytic activity towards organic pollutants†
Cite this: RSC Adv., 2020, 10, 10910
a
b
a
a
Elzbieta Regulska, ‡ Piotr Olejnik,‡ Halyna Zubyk, Justyna Czyrko-Horczak,
cd
b
e
a
Manuel N. Chaur,
Monika Tomczykowa, Olena Butsyk, Krzysztof Brzezinski,
Luis Echegoyen * and Marta E. Plonska-Brzezinska
f
b
*
Metallophthalocyanine (MPc) and carbon nano-onion (CNO) derivatives were synthesized and
characterized by using ultraviolet-visible spectroscopy, infrared and Raman spectroscopy, scanning
electron microscopy with energy-dispersive X-ray spectroscopy and X-ray powder diffraction. The
unmodified CNOs and MPc–CNO derivatives were used as photocatalysts for rhodamine B (RhB)
degradation under visible-light irradiation. The photocatalytic studies revealed that the MPc–CNO
nanostructural materials simultaneously exhibited a high absorption capacity and an excellent visible-
light-driven photocatalytic activity towards RhB. These nanostructures possess great potential for use as
active photocatalysts for organic pollutant degradation.
Received 30th January 2020
Accepted 10th March 2020
DOI: 10.1039/d0ra00896f
rsc.li/rsc-advances
21
four pyrrole groups instead of carbons. Pcs are planar
aromatic macrocycles consisting of four isoindole units with
Introduction
Degradation of water pollutants through semiconductor medi- delocalized electrons over the carbon and nitrogen atoms.
ated photocatalysis has attracted attention because it offers Because of their structures, Pcs exhibit interesting electrical
1
–3
22,23
24–26
a promising pathway for environmental pollution problems.
Various systems have been studied and employed as photo- a good thermal and chemical stability, and can be applied to
properties,
strong absorption in the visible region,
27
4,5
28–31
catalysts in the past few decades. Among these studied pho- versatile organic reactions.
The structure of Pcs enables
6
–8
tocatalysts, carbon materials,
,
organic derivatives or them to be combined with macromolecular structures and/or
metal oxides, inorganic nanoparticles and metals, which broadens their applicability.
and hybrid materials combining two or more tion of Pcs with the metal atom (metallophthalocyanine, MPc)
9
–13
14
32,33
composites,
The combina-
15,16
nanocrystals
components with different chemical natures have been in the complex optimizes the Pc properties, mainly by
3
,14,17,18
34,35
36
used.
aromatic tetraazaporphyrins, also appear among these trochemical activity.
Oen, phthalocyanines (Pcs), derivatives of the increasing their photochemical,
photocatalytic and elec-
32,37,38
19,20
systems.
Pcs are synthetic analogues of porphyrins, in which
MPc complexes exhibit an extraordinary molecular stability
the nitrogen atoms in the aromatic polyene ring connect the and negligible toxicity. To date, MPcs and Pcs have been
successfully incorporated as active components in semi-
39
40,41
conductor and electrochromic devices,
organic eld effect
41,42
43
44
a
Faculty of Chemistry, University of Bialystok, Ciolkowskiego 1K, 15-245 Bialystok, transistors,
light-emitting devices, organic memristors,
light-driven micromotors, and sensors,
well as in photocatalytic applications,
requiring antimicrobial and antioxidant activities, imaging
and therapeutic applications, etc. Within this context, Pc
applications are restricted by the difficulties connected with the
great tendency of the planar macrocycles to aggregate, which
impairs the physico-chemical activity. The successful incorpo-
45,46
47
48,49
Poland
b
solar cells,
as
Faculty of Pharmacy with the Division of Laboratory Medicine, Medical University of
29,50–53
applications
54
Bialystok, Mickiewicza 2A, 15-222 Bialystok, Poland. E-mail: marta.
plonska-brzezinska@umb.edu.pl; Tel: +48 85 738 5687
55
c
Departamento de Qu ´ı mica, Facultad de Ciencias Naturales y Exactas, Universidad del
Valle, Cali, Colombia
d
Centro de Excelencia en Nuevos Materiales (CENM), Universidad del Valle, Cali,
Colombia
e
Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8, 182 21, ration of Pcs or MPcs into larger macromolecular systems
Czech Republic
requires their self-organization and dispersibility to be
f
Department of Chemistry, University of Texas at El Paso, 500 W. University Ave., El
controlled. These connections provide unique properties, such
Paso, TX 79968, USA. E-mail: echegoyen@utep.edu
as increased surface areas, long lifetimes, facile recovery and
†
1
‡
Electronic supplementary information (ESI) available. See DOI:
0.1039/d0ra00896f
easy separation of the catalyst. Among these systems, poly-
56
57,58
59
mers and inorganic
and organic nanoparticles have been
These authors contributed equally to this work.
10910 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
studied. Synthetic efforts have also been devoted to imple- degradation of organic pollutants. For this study, a model
menting carbon nanostructures (CNs) into these macromolec- system of rhodamine B (RhB) was used.
39,60,61
ular systems.
and noncovalent modications were applied.
covalent modication rst inuences the electronic properties
In the case of these nanostructures, covalent
62–64
Although
Experimental
of CNs, noncovalent modication is relatively weak and can Materials and methods
lead to the easy removal of the immobilized molecule from the
surface, and hence, this type of modication is not applicable in
many areas.
CNOs were obtained according to the method proposed by
72
Kuznetsov, in which diamond nanoparticles (NDs, Carbodeon
mDiamond Molto) with a diameter of 4.2 ꢀ 0.5 nm and a ND
content of $97 wt% were annealed. All the chemicals and
solvents were commercially available and used without further
purication: nanodiamond powder (mDiamond®Molto, Carbo-
deon); 1,2-dicyanobenzene (ꢁ98%, Sigma-Aldrich); ammonia
solution (25% pure p.a., Sigma-Aldrich); maleimide (ꢁ99%,
Sigma-Aldrich); tetrahydrofuran (pure p.a., Avantor); 2-propanol
Fullerenes and carbon nanotubes (CNTs) are a type of CN
43,63,65–67
that exhibit interesting photophysical properties,
such
as an excellent electron acceptor ability, a small reorganization
energy and an ability to promote ultrafast charge separation
63
together with very slow charge recombination. The rst report
regarding a covalently linking a Ni(II)Pc moiety to C60 through
68
a Diels–Alder reaction was published in 1995. To date, a large
variety of covalently and noncovalently modied fullerene and
CNT acceptor units have been synthesized, and their photo-
physical properties were studied both in solution and in the
(pure p.a., Avantor); acetone (99.5% pure p.a., Avantor); 2-
mercapto-4-methyl-5-thiazoleacetic acid (ꢁ98%, Sigma-
Aldrich); zinc chloride ($99%, Sigma-Aldrich); nickel(II) chlo-
ride (ꢁ98%, Sigma-Aldrich); copper(II) chloride (ꢁ97%, Sigma-
Aldrich); hydrochloric acid (35–38% pure p.a., Avantor); sul-
phuric acid (95% pure p.a., Avantor); sodium chloride (pure
p.a., Avantor); aluminium powder (ꢁ99.99%, Avantor); sodium
61,69,70
solid phase.
In this study, we used perfectly spherical CNs, called carbon
nano-onions (CNOs). CNOs may have different sizes and shapes
and are strongly connected to each other with their formation
(Sigma); 1-octanol ($95%, Sigma-Aldrich); potassium perman-
71–74
procedure.
These structures, which are formed from nano-
ganate (Avantor); dimethyl sulphoxide (DMSO, pure p.a.,
Avantor); and methanol (99.5% pure p.a., Avantor).
diamond particles (NDs), are the most common CN in this
group, mainly because their high reactivity is connected with
72,75,76
their perfectly spherical structures.
CNOs derived from
Synthetic procedures
NDs are recognized as ‘zero-dimensional’ nanostructures due to
their perfect spherical shape (6–8 graphitic shells and a diam-
Synthesis of pristine CNOs. Commercially available ND
77
eter of 5–6 nm). Due to these properties, many covalent reac- powder with a crystal size between 4–6 nm was used for the
tions can occur on CNOs to attach multiple groups to their preparation of the CNOs. First, the NDs were placed in
7
8
surfaces. Among these covalent reactions are amidation,
a graphite crucible, which was transferred to an Astro carbon-
79,80
81,82
oxidation,
1,3-dipolar cycloaddition,
[2 + 1] cycloaddi- ization furnace. The air in the furnace was removed by applying
83
84
85
tion,
nucleophilic substitution,
diazonium addition,
a vacuum, which was followed by purging with He. The NDs
84
86
87
ꢂ
reduction, uorination and radical addition.
were annealed at 1650 C under a 1.1 MPa He atmosphere with
ꢂ
ꢃ1 76
Until now, attempts have been already made to use these a heating rate of 20 C min
CNs in photoactive devices. However, since then, no reports in air at 400 C to remove any amorphous carbon.
. Finally, the CNOs were annealed
ꢂ
using CNOs as photocatalysts for the degradation of organic
Synthesis of H Pc. Metal-free phthalocyanine (H Pc) was
2 2
pollutants have been published, to the best of our knowledge. synthesized according to a procedure described in the literature
For example, CNOs were used as a hole collection layer in zinc- by using phthalonitrile and sodium alkoxide in an alcoholic
8
8,89
phthalocyanine-based organic photovoltaic devices.
The solution (Fig. 1). 1,2-dicyanobenzene (100 mg) was dissolved in
ꢂ
photocurrent was increased by a factor of 5.5 compared to that 50 mL of 1-octanol. The reaction was carried out at ca. 150 C for
of solar devices without CNOs. A device based on a perovskite 5 hours, and then, AlCl3 (10 mg, synthesized by annealing
88
crystalline lm with oxidized CNOs incorporated into the hole aluminium in the presence of hydrogen chloride) and NaCl (10
ꢂ
transporting
layer
along
with
poly(3,4- mg) were added carefully. This mixture was stirred at 180 C for
ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) 12 hours. The obtained product was ltrated and washed with
was prepared, resulting in a signicant enhancement in the a variety of solvents to remove impurities (water, ethanol,
89
1
power conversion efficiency (PCE) from 11.07 to 15.26%. The acetone). H NMR (400 MHz, C
6 6
D , ppm): d 9.44–9.42 (m,
larger CNO structures (30 nm in diameter) were also applied in aromatic), 7.33–7.27 (m, aromatic), 6.82–6.78 (m, aromatic).
dye sensitized solar cells and used as a counter electrode, but
Synthesis of MPc. The metallophthalocyanines (CuPc, NiPc
35
the PCE was comparable to that of a commonly used platinum and ZnPc) were synthesized according to a known procedure.
90
electrode.
The synthesis of the metallophthalocyanines involved the
We applied CNO as a platform for the assembly of MPcs. In reaction of 1,2-dicyanobenzene with either zinc chloride, nick-
this study, we covalently modied the outer CNO shells to form el(II) chloride or copper(II) chloride in the presence of ammonia.
ꢂ
a chemically stable series of MPc-based CNOs. We tested these The reaction was carried out at 180–190 C for 5 hours using
3
MPc-based CNOs as visible-light photocatalysts for the DMSO. Next, AlCl (10 mg, synthesized by annealing aluminium
in the presence of hydrogen chloride) and NaCl (10 mg) were
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 10910–10920 | 10911

View Article Online
RSC Advances
Paper
Fig. 1 Schematic illustration of the whole synthesis procedure for (a) Pc, (b) MPc, and (c) Pc–CNO and MPc–CNO derivatives.
ꢂ
added carefully. This mixture was stirred at 180 C for 12 hours. DMF was used as a solvent, and the reaction was carried out at
ꢂ
The products were puried by washing with ethanol and 100 C overnight. The products were washed with acetone.
ꢂ
acetone and dried overnight at 50 C.
Synthesis
chlorophthalocyanine (with 1–16 chlorine atoms attached to the
benzene rings of the phthalocyanine molecule) was synthe- The lms were imaged by secondary electron scanning electron
sized by melting a mixture of AlCl
(synthesized by annealing microscopy (SEM) using an FEI Tecnai S-3000N instrument
aluminium in the presence of hydrogen chloride), NaCl and (Tokyo, Japan). The accelerating voltage of the electron beam
of
Cl–H Pc
and
Cl–MPc.
Poly-
2
Methods
4
3
ꢂ
H
2
Pc or MPc under owing chlorine at 180–190 C for 14 hours. was 30 keV. The energy dispersive X-ray spectroscopy (EDX)
The obtained product was ltrated and washed with a variety of analyses were performed with an ASPEX system fully integrated
solvents (ethanol and acetone) to remove impurities and dried and automated with a scanning electron microscope (S-3000N).
1
ꢂ
overnight at 50 C.
The H NMR spectra were recorded with an Agilent VNMRS
Synthesis of CNO-1. The CNOs (50 mg) were dispersed in system operated at 400 MHz, and CDCl
5 mL of N,N-dimethylsulphoxide (DMSO). Then, 24.5 mg of The powder diffraction data were measured at 293 K using
maleimide was added to this solution, and the resulting mixture a SuperNova diffractometer (Agilent) with a CCD detector and
3
was used as the solvent.
1
ꢂ
was reuxed with zinc chloride (5 mg) at 110 C for 24 hours. a Cu-K
The reaction mixture was poured into excess of tetrahydrofuran was 148 mm. Prior to the experiment, all the samples were
THF). Next, the mixture was washed several times with acetone. loaded into capillaries with a diameter of 0.5 mm.
radiation source, and the sample-to-detector distance
a
(
The maleimide derivatives of CNO were dried under a vacuum
The room temperature Raman spectra obtained in the range
ꢃ1
ꢂ
and heated in an oven at 50 C overnight to give the product between 3500 and 100 cm
were recorded with Renishaw
CNO-1.
Raman InVia microscope equipped with a high sensitivity ultra-
Synthesis of CNO-2. CNO-2 was synthesized by rst dissolv- low noise CCD detector. Radiation from an argon ion laser (514
ing 50 mg of CNO-1 in 5 mL of DMSO. Then, 23.8 mg of 2- nm) operated with an incident power of 1.15 mW was used as
mercapto-4-methyl-5-thiazoleacetic acid was dissolved in 2 mL the excitation source. The Fourier transform infrared spectros-
ꢂ
of 2-propanol. The reaction was carried out at 70 C for 10 copy (FTIR) spectra were recorded in the range between 4000
ꢃ1
hours. The reaction mixture was poured into excess of tetrahy- and 200 cm with NICOLET IN10 MX infrared microscope
drofuran (THF). The thiazole–maleimide functionalized CNOs (Thermo Scientic) operated at room temperature under an N
CNO-2) were washed several times with deionized water and atmosphere. The microscope was operated mainly in the
acetone. The CNO-2 product was dried under a vacuum and reectance mode, and the MCT detector was cooled with liquid
2
(
ꢂ
heated at 50 C overnight.
nitrogen. Additionally, the abovementioned MCT detector was
Synthesis of Pc–CNOs (CNO-3, CNO-4, CNO-5, and CNO-6). utilized to map the MPc derivatives. The spectra were collected
ꢃ1
The products CNO-3 (H
2
Pc–CNO), CNO-4 (CuPc–CNO), CNO-5 with a resolution of 4 cm , 256 scans were averaged to obtain
(
NiPc–CNO) and CNO-6 (ZnPc–CNO) were synthesized by a single spectrum and apodized with a triangular function, and
using 50 mg of CNO-2 and H Pc or MPc (CuPc, NiPc and ZnPc). a zero-lling factor of 1 was applied. The spectra were collected
2
2
for a 100 mm (0.01 mm area) square region of the sample. All
10912 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
the spectra were corrected with conventional soware to elim- for the qualitative characterization of the metal-free and the
inate the variation of the analysed thickness with the MPc–CNO derivatives. The FTIR spectra of the CNOs and their
wavelength.
MPc derivatives were recorded, as shown in Fig. 2. Additionally,
The photocatalytic degradation experiments were investigated the spectra of H Pc and the MPcs are presented for comparison
2
in a 50 mL glass cell. The reaction mixture consisted of 20 mL of (Fig. 2.P(I)).
ꢃ1
the rhodamine B aqueous solution (12.5 mg L ) and a photo-
The broad, unshaped signals in the higher frequency range
ꢃ1
ꢃ1
ꢃ1
catalyst (1.5 g L ). Prior the photodegradation studies, adsorp- (3500–3100 cm with a maximum ca. 3350 cm ) correspond to
tion experiments were carried out. The suspension of the model free N–H stretching vibrations (Fig. 2.P(I)). The signals in the
pollutant and the appropriate photocatalyst was kept in the dark range between 3100–2900 cm can be attributed to –C–H–
while stirring for 1 hour to attain equilibrium. To monitor the asymmetric and symmetric stretching vibrations. Pcs have 18
progress of the degradation reaction during irradiation for 2 p-conjugated electron aromatic ring systems, which are
hours with simulated solar light (SUNTEST CPS+), samples were composed of four pyrrole units linked by four aza (–N]C–)
collected and centrifuged every 15 min, and the supernatant was groups at the a-carbon atoms of the pyrrole units.
ꢃ1
21
analysed using UV-vis spectroscopy (HITACHI U-2800A).
The infrared absorption band between ca. 1700 and
ꢃ1
8
00 cm is characteristic for metal-free and metal-containing
ꢃ1
Pcs. The peaks located at ca. 1610 cm are correlated with
the conjugated carbons (–C]C–) and aza (–N]C–) groups. The
Results and discussion
Synthesis of MPcs and MPc–CNOs
The synthesis of H
dure using phthalonitrile.
2
Pc was based on the most common proce-
91,92
The cyclotetramerization reaction
of phthalonitrile proceeded in the presence of a reducing agent,
sodium alkoxide in an alcoholic solution (Fig. 1a), that per-
formed the function of a template during ring formation. Bau-
mann et al. suggested that a nucleophilic attack by the alkoxide
anion on the cyano group of phthalonitrile leads to form 1-
alkoxy-3-iminoidoindolenine, and in the subsequent reduction
92
2
and cyclization reactions, forms H Pc. The analogous reaction
was carried out in the presence of metal ions (Fig. 1b), which led
to the formation of Pc moieties with a complexed metal ion at
the centre of the ring (MPc). Compounds H
further employed in the preparation of Cl–H
2
Pc and MPcs were
Pc and Cl–MPcs,
2
respectively. Halogens were introduced at the periphery of the
macrocyclic scaffold (Fig. 1a and b). Halogenated H Pcs and
2
MPcs were a starting point for the covalent modication of
CNOs and the subsequent formation of the Pc–CNO and MPc–
CNO derivatives.
Simultaneously, the thiazole–maleimide functionalized
CNOs (CNO-2) were synthesized using the two-step reaction
presented in Fig. 1c, which is described in detail in the Exper-
imental section. First, a Diels–Alder reaction was performed to
93
2
incorporate maleimide into the CNOs. The sp carbon atoms
of the CNOs serve as a dienophile and react with maleimide as
a diene through a Diels–Alder reaction to form [4 + 2] cyclic
adducts. The reaction results in maleimide-functionalized
CNOs (CNO-1), which were applied as a platform for the
further reaction with 2-mercapto-4-methyl-5-thiazoleacetic acid
to synthesize the thiazole–maleimide CNO derivatives (CNO-2).
Next, CNO-2 was used as a template for the synthesis of four
different Pc–CNO derivatives, one metal-free phthalocyanine
(
H Pc–CNO, assigned later as CNO-3) and three metal phtha-
2
locyanines containing either copper (CuPc–CNO, CNO-4), nickel
NiPc–CNO, CNO-5), or zinc (ZnPc–CNO, CNO-6).
(
Fig. 2 Panel (I) FT-IR spectra of (a) CNO-1, (b) CNO-2, (c) H
CNO-3, (e) CuPc, (f) CNO-4, (g) NiPc, (h) CNO-5, (i) ZnPc, and (j) CNO-
. Panel (II) FT-IR spectra of (a) CuPc, (b) CNO-4, (c) NiPc, (d) CNO-5,
2
Pc, (d)
Spectroscopic characteristics of the MPcs and MPc–CNOs
Fourier transform infrared spectroscopy (FTIR) and Raman
6
spectroscopy were utilized as the main experimental techniques (e) ZnPc, and (f) CNO-6.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 10910–10920 | 10913

View Article Online
RSC Advances
Paper
ꢃ1
99
peaks located in the region 1330–880 cm are correlated with in the translational symmetry and the crystallite size. Fig. SI1
the structure of the Pcs and/or a substituted metal (Fig. 2.- and SI2† show the Raman spectra of the pristine CNO, CNO-1,
94
P(II)). The three strong signals located in this region can be CNO-2, H Pc, MPc, H Pc–CNO and MPc–CNO samples. The
2
2
assigned to the pyrrole rings, –C–N– stretching and the –C–H– spectra were obtained with an excitation wavelength of 514 nm
ꢃ1
deformation vibrations in the ring. The band at 1010 cm is using a He–Ne laser. The peak positions and intensities are
2
attributed to the metal-free H Pc (Fig. 2c.P(I)) and is used to summarized in Table 1.
check the purity of the MPc complexes (the N–H deformation
In general, the spectrum obtained for the pristine CNOs is
21,95,96
modes).
For the MPc derivatives, the peaks centred ca. composed of three characteristic peaks, which correspond to
ꢃ1
1540, 1490 and 1410 cm are attributed to the –C]N– and the contribution of the hexagonal mode characteristics of gra-
100
–
C]C– stretching vibrations of the phthalocyanine ring, and phene or graphite. For most Raman spectroscopic analyses of
ꢃ1
the peaks ca. 1090 and 880 cm are attributed to the vibration carbon, two G and D bands are used to characterize CNs. The
ꢃ1
of the MPc macrocycles: the isoindole deformation and aza graphite line (G line at 1580(ꢀ5) cm ) is assigned to the E2g
9
5,97
101
vibration (Fig. 2.P(II)).
In the lower wavenumbers range of species of the innite crystals. The diamond band (D line at
ꢃ1
ꢃ1
the IR spectra from 1100 to 800 cm , a few more peaks were 1332(ꢀ5) cm ), also frequently called a disorder band, is related
observed and can be assigned to planar –C–H– bending and out- to a zone-centre optical phonon with F2g symmetry.
9
4
of-plane deformations.
It can be observed that the spectra obtained for the pristine
The IR spectra analysis also showed some changes in the CNOs also have these two intense bands: G at 1576 and D at
ꢃ1
101
CNO structures aer covalent attachment of Pc moieties. The 1340 cm (Table 1). These bands are attributed to the rst-
spectra of the unsubstituted CNO (not shown) shows three order scattering band. From the spectrum of the pristine
broad signals in the range of 1540–1510, 1270–1240 and 1050– CNOs, the G band is downshied from the position of planar
ꢃ1
9
20 cm , which may be assigned to the innermost shell of the graphite, which is correlated with the inuence of bond
7
9
102
CNOs. There are some similarities between the CNO deriva- bending on the spherical CNO shells.
In addition to the
tives, the maleimide (CNO-1) and thiazole–maleimide func- strong G and D features observed in the Raman spectra of the
ꢃ1
tionalized CNOs (CNO-2), in this region (Fig. 2b.P(I) and 2c.P(I)). CNOs, some second-order scattering bands at 2667 cm were
For these and the MPc–CNO derivatives, differences are visible observed (Table 1) and detected at approximately twice the
in the higher wavenumber regions. The two broad bands in the wavenumber of the D band.
ꢃ1
range of 3430–3320 and 2960–2810 cm can be attributed to
The Raman spectra of the Pcs and their metal complexes
ꢃ1
C–H asymmetric and symmetric stretching vibrations and N–H have peaks in the region 1700–500 cm . The spectral range
98
ꢃ1
stretching vibrations of the succinimide groups, respectively.
These signals have higher intensities for the MPc–CNO deriva- atoms and is unique for each Pc.
tives in comparison to those of CNO-1 and CNO-2.
1550–1350 cm is characteristic of Pcs with different metal
1
03,104
In the Raman spectra of
ꢃ1
CuPc, we distinguish a band at 1524 cm (B1g). This band is
Aer the functionalization of the CNOs with the MPcs, the very important because it is sensitive to the size of the central
ꢃ1
characteristics signals of phthalocyanines substituted with metal ion. The band at 1524 cm is considered as a ‘marker’ of
ꢃ1
metals are also visible in the infrared spectra (1700–800 cm ), crystal structure modication, and the shi in B shied by
1
g
ꢃ1 104
ꢃ1
which were discussed in detail. The peak located at ca. 50 cm
610 cm correlated with the conjugated carbon atoms (–C] 1551 and 1504 cm in the Raman spectra of NiPc and ZnPc,
.
The band at 1524 cm observed for CuPc shis to
ꢃ1
ꢃ1
1
C–) has a higher intensity for the MPc–CNO derivatives than for respectively (Fig. SI2†). This region also consists of overtones or
the MPcs (Fig. 2.P(II)). This observation successfully conrmed combination bands corresponding to the –C–H– stretching
ꢃ1
21
the incorporation of metallophthalocyanines into the multi- modes in the 1550 to 1300 cm range. Symmetric and anti-
fullerene conjugated cages. symmetric –C–H– stretching modes are observed with similar
Fig. 3 shows the measurements performed using an infrared frequencies for both non-metallated and metallated
21
mapping method. The measurement maps show the optical phthalocyanines.
distribution of the specic signals at a dened wavelength, with Additionally, in the 3200–2850 cm region (Fig. SI2†), the
the signal intensity imaged using an appropriate colour. The –N–H– and –C–H– stretching vibrations observed for the
ꢃ1
red colour indicates the highest intensity signal for the whole unsubstituted Pc (H
spectrum. The images captured by an optical microscope reveal and 2899 cm . The absence of these bands in the MPc spectra
2
Pc) are recorded at 3008, 2989, 2946, 2902
ꢃ1
a fragment of the MPcs or MPc–CNO derivatives on the slide may indicate the successful substitution of the H
with dimensions of 700 ꢄ 800 mm. Fig. 3 illustrates the distri- with metals.
2
Pc moieties
bution proles obtained for the specic spectra of the MPc and
Ultraviolet-visible (UV-vis) absorption was used as an effec-
MPc–CNO derivatives and indicates the presence and uniform tive approach to characterize the optical properties of the CNO
distribution of MPcs on the carbon nanoparticle surface. The and MPc–CNO derivatives (Fig. 4). The UV-vis absorption
arrangement prole obtained for the MPc based on the char- spectra of the CNO derivatives show (Fig. 4a) broad absorption
ꢃ1
acteristic peaks (at 1410, 1330 or 1100 cm ) shows the presence bands at 285 and 332 nm, which are characteristic of the p–p*
2
of MPcs across the entire experimental area (0.01 mm area).
electron transition in the polyaromatic systems of the curved
105
Two characteristic areas of the CNs and Pc moieties are graphite layers. The UV-vis absorption spectra of the MPcs
presented in the Raman spectra (Fig. SI1 and SI2†). The Raman showed a typical shape for Pcs, with B-band (in the region
spectra of carbonaceous materials are very sensitive to changes between 300 and 370 nm and centred at 320 and 335 nm) and Q-
10914 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
Fig. 3 Infrared mapping set obtained for the MPc and MPc–CNO derivatives.
band (in the region between 550 and 750 nm and centred at 670 of these macrocycles on the CNO surface, the morphology of
nm) with various intensities. The Zn–Pc and its CNO derivative these systems radically changes to a morphology similar to that
have an additional shoulder centred at 385 nm (Fig. 4d). Three of carbon materials. The CNO-derivatives result in a homoge-
peaks and two shoulders were located in the absorption band in neous distribution of the Pcs on the CNO surfaces. The energy
the UV region, which is preceded by the ultraviolet band of the dispersive X-ray (EDX) spectra (Fig. 5i–k) of the CNO-4, CNO-5
106
Pc molecule. The analysis of the spectral data show differ- and CNO-6 systems reveal that the derivatives mainly contain
ences between Zn–Pc (Fig. 4d), Cu–Pc (Fig. 4b) and Ni–Pc C, N, and the metals Cu, Ni or Zn. The EDX analysis conrmed
(Fig. 4c).
the successful functionalization of the CNO surface with met-
The spectra recorded for Zn–Pc and its CNO derivative allated Pcs.
exhibit a high extinction coefficient and sharp Q bands, while
XRD was performed to identify the phase composition and
the other two MPcs exhibit wider bands with lower intensities. crystallinity of the synthesized Pc and the CNO–MPc derivatives.
This phenomena suggests strong aggregation interactions The XRD patterns of the pristine NDs (Fig. 6a), the pristine
between the molecules. Additionally, the B-band in the spectra
of Cu–Pc (Fig. 4b) is more intense than the Q-band, which also
107
indicates signicant aggregation. The MPc–CNO derivatives
show the same trend and exhibit an obvious UV-vis light
absorption ability. The morphology of the pristine metallated
Pcs and their CNO derivatives were observed by scanning elec-
tron microscopy (SEM) (Fig. 5).
The SEM images of an Au foil covered with the Pcs and the
Pc–CNO derivatives are shown in Fig. 5a–d and e–h, respec-
tively. The non-metallated Pcs and those with coordinated
metal ions in the centre formed needle-like structures with
different diameters and lengths. Aer covalent immobilization
Table 1 Raman parameters of the characteristic bands of the pristine
CNOs and their Pc derivatives
ꢃ1
ꢃ1
ꢃ1
Sample
D (cm
)
G (cm
)
2D (cm )
CNO
1339
1335
1345
1343
1338
1339
1333
1576
1576
1577
1585
1585
1597
1582
2667
2689
2684
2690
2681
2686
2678
CNO-1
CNO-2
CNO-3
CNO-4
CNO-5
CNO-6
Fig. 4 UV-vis spectra of (a) CNO-1 and CNO-3, (b) CuPc and CNO-4,
c) NiPc and CNO-5, and (d) ZnPc and CNO-6.
(
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 10910–10920 | 10915

View Article Online
RSC Advances
Paper
Fig. 5 (a–h) SEM images of (a) H
2
Pc, (b) CuPc, (c) NiPc, (d) ZnPc, (e) CNO-3, (f) CNO-4, (g) CNO-5 and (h) CNO-6. (i–k) Energy dispersive X-ray
spectroscopy analyses of (i) CNO-4, (j) CNO-5 and (k) CNO-6.
CNOs (Fig. 6b) and the functionalized CNOs (CNO-1, Fig. 6c) are from NDs to CNOs was observed during the annealing process
presented in Fig. 6. The ND prole reveals the presence of of the starting material (comparison of Fig. 6a and b).
ꢂ
a mixture of various phases. In the ND materials, the strongest
An asymmetric broad reection in the range between 23–27
ꢂ
ꢂ
reection at 2q ¼ 43.8 corresponds to the (111) basal plane of and a second one with a maximum at 43.0 were observed. They
ꢂ
the diamond structure, and the reection at 2q ¼ 21.5 corre- are attributed to the (002) and (100) planes of graphite,
75,108
109
sponds to a graphite-like amorphous phase.
The conversion respectively (Fig. 6b and c).
The broad signal centred
ꢂ
2
approximately 23–27 suggests the contribution of some sp -
bonded carbons in the CNO samples, and can be assigned to
graphitic carbon. This signal is relatively broad, has a weak
intensity and is observed for every MPc–CNO derivative
(
Fig. 6f, h and i). For these derivatives, a reection at approxi-
ꢂ
mately 43.0 is also observed (a broad reection peaks marked
2
with star in Fig. 6). Briey, if H (Fig. SI3†) is substituted by the
metal centre, then the (400) and (800) peaks at 2q ¼ 14.62 and
ꢂ
10
2
9.41 , respectively (marked in Fig. SI3†), have a lower inten-
1
sity. All the proles of the MPc–CNOs conrmed the presence
of CNO and MPC components in the obtained materials.
Photocatalytic activity of MPc–CNOs
To test the photocatalytic activity of the MPc–CNOs for the
degradation of organic pollutants, rhodamine B (RhB) was
selected as a model compound representing a group of dye
contaminants. The generally accepted mechanism for the
photocatalytic degradation of organic molecules, such as RhB,
is the formation of highly active species, which react with and
degrade the targeted molecules to form smaller molecules that
are less toxic, preferably water and carbon dioxide. Similar to
other carbon nanostructures, e.g., fullerenes, CNOs can be used
2
Fig. 6 XRD patterns of (a) NDs, (b) CNOs, (c) CNO-1, (d) H Pc, (e)
CuPc, (f) CNO-4, (g) NiPc, (h) CNO-5, (i) ZnPc and (j) CNO-6.
10916 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
as semiconductors, as they demonstrate a photocatalytic Table 2 Photocatalytic degradation efficiencies and rate constants
obtained for CNO and MPc–CNOs
activity. In the presented paper, we investigated the photo-
catalytic activity of the Pc-functionalized CNOs, which we
compared with the behaviour of pristine CNOs and MPc,
Parameter
CNO
CNO-3
CNO-4
CNO-5
CNO-6
separately (Fig. 7). We found that both the unmetallated Pcs and h (%)
all of the metallated Pcs demonstrated poor photocatalytic k (min
93
0.0235
98
0.0466
97
0.0301
98
0.0494
70
0.0115
ꢃ1
)
behaviours. The photodegradation efficiency (h) of RhB, dened
as
ꢀ
ꢃ Cꢁ
C
0
the presence of the MWCNTs functionalized with Zn–Pcs, 88%
of RhB was degraded using irradiation with visible light.
h ¼
ꢄ 100%
(1)
C
111
Moreover, the photocatalytic reaction kinetics was investi-
gated based on the pseudo-rst order time-dependent relation
expressed by the following equation:
did not reach more than 12% for the pristine MPcs (see Table 2).
However, when the MPc–CNOs were applied as catalysts, h
signicantly increased. The photocatalytic degradation effi-
ciencies obtained for the MPc–CNOs were signicantly higher,
though very similar to each other, except for CNO-6. In the
presence of both CNO-5 and CNO-3, 98% of RhB was decom-
posed, and the degradation efficiency did not differ greatly
when CNO-4 was used (97%). However, the application of CNO-
ꢀ
ꢁ
C
ꢃln
¼ kt
(2)
C
0
The calculated photocatalytic degradation reaction rate
ꢃ1
constant was the highest for CNO-5 (0.0494 min ) and
6
led to a 70% photodegradation efficiency. Interestingly, the
decreased in the following order: CNO-5 > CNO-3 > CNO-4 >
CNO > CNO-6 (Table 2). There are two factors that contribute to
the nal photocatalytic activity of the applied material, namely,
pristine CNO was responsible for the degradation of not less
than 93% of the model pollutant. The pristine CNOs and MPc–
CNO derivatives have a high photocatalytic activity in compar-
ison with the other phthalocyanine-functionalized CNs. For
example, pristine multi-walled carbon nanotubes (MWCNTs)
(i) the adsorption of the dye and (ii) photocatalytic degradation.
In fact, for CNO-6, which was functionalized with ZnPc to the
111
higher extent, the smaller photocatalytic activity was observed.
On the other hand, the nal photodegradation efficiency
depends also on the effective harvesting of the irradiation. In
that respect the HOMO–LUMO gap is important. Indeed, the
phthalocyanine-functionalized CNOs have lower HOMO–LUMO
energy band gaps, and that enhances the photocatalytic activity.
NiPc and CuPc have a smaller HOMO–LUMO band gap than
had almost no photocatalytic activity towards RhB (18.5%). In
112
ZnPc. The HOMO in CuPc is 3d metal-like, whereas in Ni and
112
Zn phthalocyanines, the HOMO is localized on the Pc ring.
However, the rst ionization process removes an electron from
the Pc a1u orbital in all cases. Moreover, also the formation of
the stable and long-lived excited states plays a role. It was re-
ported elsewhere that CNOs due to their multi-shell structure
113
stabilize charge-transfer states.
Therefore, merging MPcs
with CNOs leads to the formation of the nanostructured catalyst
+
ꢃ
that upon excitation generates the MPcc and CNOc ephemeral
113
species. The latter, in the aqueous environment contribute to
the formation of hydroxyl and superoxide radicals, which are
responsible for RhB degradation. Based on the observed results,
we could conclude that the most advantageous effect of those
factors was reached for CNO-5, CNO-3 and CNO-4.
Conclusions
Several Pc- and MPc-based derivatives possessing unique
physico-chemical properties, including a photocatalytic activity
towards organic pollutants, were synthesized. The absorption
experiments showed that the functionalization of the CNO
cages with MPc moieties results in the formation of photoactive
systems. RhB was selected as a model compound representing
a group of dye contaminants. The photodegradation efficiency
of RhB did not reach more than 12% for the pristine MPcs.
Fig. 7 (a) The photocatalytic degradation profiles obtained for RhB
with CNO, H Pc, MPcs and MPc–CNOs. (b) The photocatalytic RhB
2
degradation kinetics obtained with CNO and MPc–CNOs.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 10910–10920 | 10917

View Article Online
RSC Advances
Paper
However, when the MPc–CNOs or pristine CNOs were applied as
catalysts, the photodegradation efficiency signicantly
increased. The photocatalytic degradation efficiencies obtained
using the MPc–CNOs and CNOs were as high as 98% or 93%,
respectively. These pristine and MPc-based CNOs show a high
photocatalytic activity in comparison with other Pc-
functionalized CNs.
17 X. Liu, C. Chen, H. Ye, Y. Jia, Y. Wu, A. Jin, Y. Wang and
X. Chen, Carbon, 2018, 131, 213–222.
18 A. Tiwari, N. V. Krishna, L. Giribabu and U. Pal, J. Phys.
Chem. C, 2018, 122, 495–502.
19 Functional Phthalocyanine Molecular Materials, ed.J. Jiang,
Springer Berlin Heidelberg, Berlin, Heidelberg, 2010, vol.
135.
2
0 H. Pan, C. Chen, K. Wang, W. Li and J. Jiang, Chem.–Eur. J.,
015, 21, 3168–3173.
2
Conflicts of interest
2
1 C. Murray, N. Dozova, J. G. McCaffrey, S. FitzGerald,
N. Shazadeh and C. Cr ´e pin, Phys. Chem. Chem. Phys.,
There are no conicts to declare.
2010, 12, 10406.
2
2
2
2
2 E. Ermi ¸s , Y. Çimen, F. Dumluda ˘g , A. R. Ozkaya, B. Salih and
¨
¨
˘
Acknowledgements
O. Bekaroglu, Polyhedron, 2013, 49, 129–137.
3 S. Nakano, Y. Kage, H. Furuta, N. Kobayashi and S. Shimizu,
Chem.–Eur. J., 2016, 22, 7706–7710.
4 C. Bozo ˘g lu, M. Arıcı, A. L. U ˘g ur, A. Erdo ˘g mu ¸s and A. Koca,
Synth. Met., 2014, 190, 56–65.
5 H. Abramczyk, B. Bro ˙z ek-Płuska, K. Kurczewski,
M. Kurczewska, I. Szymczyk, P. Krzyczmonik, T. Błaszczyk,
H. Scholl and W. Czajkowski, J. Phys. Chem. A, 2006, 110,
The authors thank the National Science Center (NSC), Poland,
for their generous support of this work (grant #2012/05/E/ST5/
03800 to M. E. P.-B.). L. E. thanks the Robert A. Welch Foun-
dation for an endowed chair, grant #AH-0033, and US NSF
grants: PREM program (DMR-1205302) and CHE-1408865.
8
627–8636.
References
2
6 J. Blochwitz, M. Pfeiffer, T. Fritz and K. Leo, Appl. Phys. Lett.,
1
2
3
4
5
6
7
8
9
D. Wang, G. Ye, X. Wang and X. Wang, Adv. Mater., 2011, 23,
122–1125.
Q. Liang, M. Zhang, C. Liu, S. Xu and Z. Li, Appl. Catal., A,
016, 519, 107–115.
M. M. Mohamed, I. Ibrahim and T. M. Salama, Appl. Catal.,
A, 2016, 524, 182–191.
J. Liu, Y. Liu, N. Liu, Y. Han, X. Zhang, H. Huang, Y. Lifshitz,
S.-T. Lee, J. Zhong and Z. Kang, Science, 2015, 347, 970–974.
A. Kubacka, M. Fern ´a ndez-Garc ´ı a and G. Col ´o n, Chem. Rev.,
1998, 73, 729–731.
˙
˘
˘
1
27 I. Degirmencioglu, R. Bayrak, M. Er and K. Serbest,
Polyhedron, 2011, 30, 1628–1636.
28 L. Zhi, T. Gorelik, J. Wu, U. Kolb and K. M u¨ llen, J. Am. Chem.
Soc., 2005, 127, 12792–12793.
29 S. Z. Yildiz, S. Colak and M. Tuna, J. Mol. Liq., 2014, 195, 22–
29.
30 C.-H. Lee, J. Guo, L. X. Chen and B. K. Mandal, J. Org. Chem.,
2008, 73, 8219–8227.
31 S. Shimizu, S. Nakano, T. Hosoya and N. Kobayashi, Chem.
Commun., 2011, 47, 316–318.
32 E. G u¨ zel, S. G u¨ ney and M. Kandaz, Dyes Pigm., 2015, 113,
416–425.
33 T. Fukuda, J. Sato, N. Hashimoto and N. Kobayashi, Chem.
Commun., 2014, 50, 14269–14272.
34 S. Cogal, S. Erten-Ela, K. Ocakoglu and A. U. Oksuz, Dyes
Pigm., 2015, 113, 474–480.
2
2
012, 112, 1555–1614.
S. Hu, Y. Ding, Q. Chang, J. Yang and K. Lin, Appl. Surf. Sci.,
015, 355, 774–777.
2
S. K. Movahed, Z. Piraman and M. Dabiri, J. Photochem.
Photobiol., A, 2018, 351, 208–224.
H. L. Chen, C.-J. Li, C.-J. Peng, H.-J. Leu and W.-H. Hung,
ACS Appl. Mater. Interfaces, 2017, 9, 327–334.
M. Zhang, Q. Liang, S. Xu and Z. Li, Optik, 2016, 127, 7993–
8
001.
35 A. de la Escosura, M. V. Mart ´ı nez-D ´ı az, D. M. Guldi and
T. Torres, J. Am. Chem. Soc., 2006, 128, 4112–4118.
36 A. Wichmann, G. Schnurpfeil, J. Backenk ¨o hler, L. Kolke,
V. A. Azov, D. W ¨o hrle, M. B ¨a umer and A. Wittstock,
Tetrahedron, 2014, 70, 6127–6133.
1
1
1
0 S. Ma, Q. Li, Z. Cai, Z. Ye and Y. Zhou, Appl. Organomet.
Chem., 2018, 32, e3966.
1 Z.-G. Liu, J.-Y. Wan, Z. Yang, S.-Q. Wang and H.-X. Wang,
Chem.–Asian J., 2016, 11, 1887–1891.
¨
2 E. Regulska, D. M. Rivera-Nazario, J. Karpinska,
37 H. Karaca, S. Sezer, ¸S . Ozalp-Yaman and C. Tanyeli,
M.
E.
Plonska-Brzezinska
and
L.
Echegoyen,
Polyhedron, 2014, 72, 147–156.
ChemistrySelect, 2017, 2, 2462–2470.
38 Z. Odaba ¸s , E. B. Orman, M. Durmu ¸s , F. Dumluda ˘g ,
¨
1
3 E. Regulska, D. Rivera-Nazario, J. Karpinska, M. Plonska-
Brzezinska and L. Echegoyen, Molecules, 2019, 24, 1118.
4 G. Mele, R. Del Sole, G. Vasapollo, E. Garc ´ı a-L ´o pez,
L. Palmisano and M. Schiavello, J. Catal., 2003, 217, 334–
A. R. Ozkaya and M. Bulut, Dyes Pigm., 2012, 95, 540–552.
39 J. B. Brito, D. J. C. Gomes, V. D. Justina, A. M. F. Lima,
C. A. Olivati, J. R. Silva and N. C. de Souza, J. Colloid
Interface Sci., 2012, 367, 467–471.
1
3
42.
40 M. E. S ´a nchez-Vergara, J. C. Alonso-Huitron, A. Rodriguez-
G ´o mez and J. N. Reider-Burstin, Molecules, 2012, 17,
10000–10013.
41 C. Wang, H. Dong, L. Jiang and W. Hu, Chem. Soc. Rev.,
2018, 47, 422–500.
1
5 X. Cui, Y. Wang, G. Jiang, Z. Zhao, C. Xu, A. Duan, J. Liu,
Y. Wei and W. Bai, J. Mater. Chem. A, 2014, 2, 20939–20946.
6 F. Huang, Z. Li, A. Yan, H. Zhao, H. Liang, Q. Gao and
Y. Qiang, Sci. Rep., 2017, 7, 39973.
1
10918 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020

View Article Online
Paper
RSC Advances
4
4
4
2 J. W. Perry, D. Alvarez, I. Choong, K. Mansour, S. R. Marder
and K. J. Perry, Opt. Lett., 1994, 19, 625.
3 P. Zhu, P. Wang, W. Qiu, Y. Liu, C. Ye, G. Fang and Y. Song,
Appl. Phys. Lett., 2001, 78, 1319.
4 Z. Lv, Q. Hu, Z. Xu, J. Wang, Z. Chen, Y. Wang, M. Chen,
K. Zhou, Y. Zhou and S. Han, Adv. Electron. Mater., 2019,
67 E. M. P ´e rez and N. Mart ´ı n, Chem. Soc. Rev., 2015, 44, 6425–
6433.
68 G. Schick, K.-D. Kampe and A. Hirsch, J. Chem. Soc., Chem.
Commun., 1995, 2023.
69 R. Valencia, A. Rodr ´ı guez-Fortea, A. Clotet, C. de Graaf,
M. N. Chaur, L. Echegoyen and J. M. Poblet, Chem.–Eur.
J., 2009, 15, 10997–11009.
5, 1800793.
4
5 F. Li, J. Yuan, X. Ling, L. Huang, N. Rujisamphan, Y. Li,
L. Chi and W. Ma, ACS Appl. Mater. Interfaces, 2018, 10,
70 D. Gonz ´a lez-Rodr ´ı guez, C. G. Claessens, T. Torres, S. Liu,
L. Echegoyen, N. Vila and S. Nonell, Chem.–Eur. J., 2005,
11, 3881–3893.
42397–42405.
4
4
6 M. Urbani, G. de la Torre, M. K. Nazeeruddin and T. Torres,
Chem. Soc. Rev., 2019, 48, 2738–2766.
7 J. Tong, D. Wang, D. Wang, F. Xu, R. Duan, D. Zhang, J. Fan
71 M. Bystrzejewski, M. H. Rummeli, T. Gemming, H. Lange
and A. Huczko, New Carbon Materials, 2010, 25, 1–8.
72 V. L. Kuznetsov, A. L. Chuvilin, Y. V. Butenko, I. Y. Mal'kov
and V. M. Titov, Chem. Phys. Lett., 1994, 222, 343–348.
73 A. Kharlamov, M. Bondarenko, G. Kharlamova, N. Gubareni
and V. Fomenko, Univers. J. Mater. Sci., 2013, 1(2), 78–86.
74 J.-C. Fan, H.-H. Sung, C.-R. Lin and M.-H. Lai, J. Mater.
Chem., 2012, 22, 9794.
75 S. Tomita, M. Fujii and S. Hayashi, Phys. Rev. B: Condens.
Matter Mater. Phys., 2002, 66, 245424.
76 A. Palkar, F. Melin, C. M. Cardona, B. Elliott, A. K. Naskar,
D. D. Edie, A. Kumbhar and L. Echegoyen, Chem.–Asian J.,
2007, 2, 625–633.
77 A. Hirsch, Fullerenes and Related Structures, in Topics in
Current Chemistry, 1999, vol. 199, pp. 1–65.
78 A. Palkar, A. Kumbhar, A. J. Athans and L. Echegoyen,
Chem. Mater., 2008, 20, 1685–1687.
79 M. E. Plonska-Brzezinska, A. T. Dubis, A. Lapinski,
A. Villalta-Cerdas and L. Echegoyen, ChemPhysChem,
2011, 12, 2659–2668.
and
B.
Dong,
Langmuir,
DOI:
10.1021/
acs.langmuir.9b02479.
8 A. T. Bilgiçli, M. N. Yara ¸s ir, M. Kandaz and A. Rıza Ozkaya,
Polyhedron, 2010, 29, 2498–2510.
¨
4
4
5
9 T. C. Canevari, T. M. Prado, F. H. Cincotto and
S. A. S. Machado, Mater. Res. Bull., 2016, 76, 41–47.
0 X. Zhang, L. Yu, C. Zhuang, T. Peng, R. Li and X. Li, ACS
Catal., 2014, 4, 162–170.
5
5
1 E. T. Saka and Y. Ça ˘g lar, Catal. Lett., 2017, 147, 1471–1477.
2 L. Fern ´a ndez, V. I. Esteves, A. Cunha, R. J. Schneider and
J. P. C. Tom ´e , J. Porphyrins Phthalocyanines, 2016, 20, 150–
ˆ
1
66.
3 X. Ma, M. Luo, L. Yan, N. Tang and J. Li, New J. Chem., 2019,
3, 9589–9595.
5
5
4
4 D. Unluer, A. Aktas Kamiloglu, S. Direkel, E. Bektas,
H. Kantekin and K. Sancak, J. Organomet. Chem., 2019,
900, 120936.
5
5
5
5
5
6
5 Y. Zhang and J. F. Lovell, Wiley Interdiscip. Rev.: Nanomed.
Nanobiotechnol., 2017, 9, e1420.
6 Y. Lei, R. Zhao, M. Xu, X. Zhao, X. Yang, H. Guo, J. Zhong
and X. Liu, J. Mater. Sci.: Mater. Electron., 2012, 23, 921–927.
7 S. Tombe, E. Antunes and T. Nyokong, J. Mol. Catal. A:
Chem., 2013, 371, 125–134.
80 M. E. Plonska-Brzezinska, A. Lapinski, A. Z. Wilczewska,
A. T. Dubis, A. Villalta-Cerdas, K. Winkler and
L. Echegoyen, Carbon, 2011, 49, 5079–5089.
81 V. Georgakilas, D. M. Guldi, R. Signorini, R. Bozio and
M. Prato, J. Am. Chem. Soc., 2003, 125, 14268–14269.
82 C. T. Cioffi, A. Palkar, F. Melin, A. Kumbhar, L. Echegoyen,
M. Melle-Franco, F. Zerbetto, G. M. A. Rahman, C. Ehli,
V. Sgobba, D. M. Guldi and M. Prato, Chem.–Eur. J., 2009,
15, 4419–4427.
8 A. Korkmaz and Y. Yilmaz, Main Group Chem., 2019, 18, 31–
4
2.
9 S. Hu, R. Tian, Y. Dong, J. Yang, J. Liu and S. Cao, RSC Adv.,
013, 3, 21447.
2
83 L. Zhou, C. Gao, D. Zhu, W. Xu, F. F. Chen, A. Palkar,
L. Echegoyen and E. S.-W. Kong, Chem.–Eur. J., 2009, 15,
1389–1396.
0 V. A. Basiuk, N. Alzate-Carvajal, L. V. Henao-Holgu ´ı n,
E. V. Rybak-Akimova and E. V. Basiuk, Appl. Surf. Sci.,
2
016, 371, 16–27.
84 A. Molina-Ontoria, M. N. Chaur, M. E. Plonska-Brzezinska
and L. Echegoyen, Chem. Commun., 2013, 49, 2406.
85 K. Flavin, M. N. Chaur, L. Echegoyen and S. Giordani, Org.
Lett., 2010, 12, 840–843.
´
6
1 D. Gonz ´a lez-Rodr ´ı guez, T. Torres, M. A. Herranz,
L. Echegoyen, E. Carbonell and D. M. Guldi, Chem.–Eur.
J., 2008, 14, 7670–7679.
6
6
6
6
6
2 M. R. Axet, O. Dechy-Cabaret, J. Durand, M. Gouygou and
P. Serp, Coord. Chem. Rev., 2016, 308, 236–345.
3 G. Bottari, G. de la Torre, D. M. Guldi and T. Torres, Chem.
Rev., 2010, 110, 6768–6816.
86 Y. Liu, R. L. Vander Wal and V. N. Khabashesku, Chem.
Mater., 2007, 19, 778–786.
87 A. S. Rettenbacher, M. W. Perpall, L. Echegoyen, J. Hudson
and D. W. Smith, Chem. Mater., 2007, 19, 1411–1417.
88 H. Mizuno, K. Nagano, S. Tomita, H. Yanagi and
I. Hiromitsu, Thin Solid Films, 2018, 654, 69–76.
89 D. Zheng, G. Yang, Y. Zheng, P. Fan, R. Ji, J. Huang,
W. Zhang and J. Yu, Electrochim. Acta, 2017, 247, 548–557.
90 I. Y. Y. Bu, Sol. Energy, 2014, 105, 236–242.
91 The Chemistry of Synthetic Dyes, ed. K. Venkatamaran,
National Chemical Laboratory Pune, India, 1971, vol. 5.
4 G. Bottari, G. de la Torre and T. Torres, Acc. Chem. Res.,
2015, 48, 900–910.
5 R. Koeppe, N. S. Saricici, P. A. Troshin and
R. N. Lyubovskaya, Appl. Phys. Lett., 2005, 87, 244102.
6 L. Moreira, J. Calbo, B. M. Illescas, J. Arag ´o , I. Nierengarten,
B. Delavaux-Nicot, E. Ort ´ı , N. Mart ´ı n and J.-F. Nierengarten,
Angew. Chem., Int. Ed., 2015, 54, 1255–1260.
This journal is © The Royal Society of Chemistry 2020
RSC Adv., 2020, 10, 10910–10920 | 10919

View Article Online
RSC Advances
Paper
9
2 F. Baumann, B. Bienert, G. R ¨o sch, H. Vollmann and 103 T. V. Basova, V. G. Kiselev, B.-E. Schuster, H. Peisert and
˜
W. Wolf, Angew. Chem., 1956, 68, 133–150.
3 C.-M. Chang and Y.-L. Liu, Carbon, 2009, 47, 3041–3049.
4 R. Seoudi, G. S. El-Bahy and Z. A. El Sayed, J. Mol. Struct.,
T. ChassA©, J. Raman Spectrosc., 2009, 40, 2080–2087.
104 D. R. Tackley, G. Dent and W. Ewen Smith, Phys. Chem.
Chem. Phys., 2001, 3, 1419–1426.
9
9
2
005, 753, 119–126.
105 S. K. Sonkar, M. Ghosh, M. Roy, A. Begum and S. Sarkar,
Mater. Express, 2012, 2, 105–114.
9
5 X.-X. Zhang, M. Bao, N. Pan, Y.-X. Zhang and J.-Z. Jiang,
Chin. J. Chem., 2010, 22, 325–332.
6 M. W. Wong, Chem. Phys. Lett., 1996, 256, 391–399.
106 M. M. El-Nahass, K. F. Abd-El-Rahman and A. A. A. Darwish,
Mater. Chem. Phys., 2005, 92, 185–189.
9
9
7 Q. Li, H. Wang, Y. Li, Y. Li and Q. Duan, Dyes Pigm., 2018, 107 X. Wang, J. Zheng, K. Qiao, J. Qu and C. Cao, Appl. Surf. Sci.,
49, 261–267. 2014, 297, 188–194.
8 B. C. Smith, Infrared spectral interpretation: a systematic 108 S. Tomita, A. Burian, J. C. Dore, D. LeBolloch, M. Fujii and
approach, CRC Press, Boca Raton, 1999. S. Hayashi, Carbon, 2002, 40, 1469–1474.
9 R. J. Nemanich and S. A. Solin, Phys. Rev. B: Condens. Matter 109 A. N. Popova, Coke Chem., 2017, 60, 361–365.
Mater. Phys., 1979, 20, 392–401. 110 G. Liu, T. Gredig and I. K. Schuller, EPL, 2008, 83, 56001.
00 D. Codorniu Pujals, O. Arias de Fuentes, L. F. Desd ´ı n 111 Y. Wan, Q. Liang, T. Cong, X. Wang, Y. Tao, M. Sun, Z. Li
1
9
9
1
1
1
Garc ´ı a, E. Cazzanelli and L. S. Caputi, Appl. Phys. A:
Mater. Sci. Process., 2015, 120, 1339–1345.
01 E. D. Obraztsova, M. Fujii, S. Hayashi, V. L. Kuznetsov,
and S. Xu, RSC Adv., 2015, 5, 66286–66293.
112 M.-S. Liao and S. Scheiner, J. Chem. Phys., 2001, 114, 9780–
9791.
Yu. V. Butenko and A. L. Chuvilin, Carbon, 1998, 36, 821– 113 M. A. Hashmi and M. Lein, J. Phys. Chem. C, 2018, 122,
26. 2422–2431.
8
02 D. Roy, M. Chhowalla, H. Wang, N. Sano, I. Alexandrou,
T. W. Clyne and G. A. J. Amaratunga, Chem. Phys. Lett.,
2003, 373, 52–56.
10920 | RSC Adv., 2020, 10, 10910–10920
This journal is © The Royal Society of Chemistry 2020