Degradation of substituted phenols with different oxygen sources catalyzed by Co(II) and Cu(II) phthalocyanine complexes

Article abstract of DOI:10.1080/00958972.2019.1589461

Research on substituted phenol degradations has received substantial attention. In this work, effective Co(II) and Cu(II) phthalocyanine complexes as catalysts were studied to degrade toxic phenols to harmless products. The effect of various process parameters, such as initial concentration of phenol, catalyst, oxygen sources, and temperature on the degradation reaction was investigated to achieve maximum degradation efficiency. The catalytic activities of Co(II) and Cu(II) phthalocyanines were evaluated for oxidation of phenolic compounds such as p-nitrophenol, o-chlorophenol, 2,3-dichlorophenol, and m-methoxyphenol. Co(II) phthalocyanine displayed good catalytic performance in degradation of 2,3-dichlorophenol to 2,3-dichlorobenzaldehyde and 2,3-dichloro-1,4-benzoquinone with the highest TON and TOF values within 3 h at 50 °C. The fate of catalyst during the degradation process was followed by UV–Vis spectroscopy.

Full text of DOI:10.1080/00958972.2019.1589461

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: https://www.tandfonline.com/loi/gcoo20
Degradation of substituted phenols with different
oxygen sources catalyzed by Co(II) and Cu(II)
phthalocyanine complexes
Ece Tugba Saka, Esra Dügdü & Yasemin Ünver
To cite this article: Ece Tugba Saka, Esra Dügdü & Yasemin Ünver (2019): Degradation of
substituted phenols with different oxygen sources catalyzed by Co(II) and Cu(II) phthalocyanine
complexes, Journal of Coordination Chemistry, DOI: 10.1080/00958972.2019.1589461
To link to this article: https://doi.org/10.1080/00958972.2019.1589461
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Degradation of substituted phenols with different oxygen sources catalyzed by
Co(II) and Cu(II) phthalocyanine complexes
ECE TUGBA SAKA*, ESRA DÜGDÜ and YASEMİN ÜNVER
Department of Chemistry, Karadeniz Technical University, 61080, Trabzon, Turkey
Research on substituted phenol degradations has received substantial attention. In this work,
effective Co(II) and Cu(II) phthalocyanine complexes as catalysts were studied in order to
degrade toxic phenols to harmless products. The effect of various process parameters such as
initial concentration of phenol, catalyst, oxygen sources and temperature on the degradation
reaction was investigated to achieve maximum degradation efficiency. The catalytic activities of
Co(II) and Cu(II) phthalocyanines were evaluated for oxidation of phenolic compounds such as
p-nitrophenol, o-chlorophenol, 2,3-dichlorophenol and m-methoxyphenol. Co(II) phthalocyanine
displayed good catalytic performance in degradation of 2,3-dichlorophenol to
2,3-dichlorobenzaldehyde and 2,3-dichloro-1,4-benzoquinone with the highest TON and TOF
values within 3 h at 50 C. The fate of catalyst during the degradation process was followed by
UV-Vis spectroscopy.
Graphical Abstract
*Corresponding author. Email: ece_t_saka@hotmail.com
1

Keywords: Degradation; Substituted phenols; Catalyst; Phthalocyanine
1. Introduction
Phenolic compounds derived from pesticides, coal conversion, petroleum and petrochemical
industries are considered by the Environmental Protection Agency (EPA) as toxic water
pollutants, based on their carcinogenic effects and high chemical stability [1] even in
concentrations less than 1 ppb. They have negative effects on marine life and aquatic
environments when discharged into streams [2]. Phenol from wastewater can be removed by
conventional technologies like adsorption, coagulation, and enzyme oxidation [3-5]. However,
these conventional technologies do not completely degrade the organic pollutants and can
produce secondary pollutants [6].
Progress has been made in the catalytic degradation of organic pollutants using different
metal catalysts [7, 8]. Phthalocyanine metal complexes (MPcs) are structurally analogous to
porphyrin complexes [9]. Due to the structural similarity with porphyrin metal complexes,
phthalocyanine complexes show bioinspired chemistry associated with porphyrin complexes
[10]. Recently phthalocyanines have been utilized as catalysts for different synthetic reactions
[11-15]. The catalytic properties of metallophthalocyanines depend on the metal and structure of
the phthalocyanine moiety. Different metals inserted in the core of the phthalocyanine ring are
active in specific reactions.
A few classes of metal complexes were developed to overcome the oxidation/selectivity
problem, particularly using bio-inspired systems [16, 17]. Some natural enzymes are able to
cleave C-H bonds at ambient conditions utilizing high-valent metal-oxo (HVMO) intermediates
[18]. Some complexes of transition metals where coordination environments stabilize such
species can mimic selective biological C-H activation pathways (such as the radical rebound
mechanism of P450) [19]. The ability of phthalocyanines and porphyrins to stabilize HVMO
species is remarkable, and complexes with porphyrin ligands have been extensively investigated
as catalysts for C-H activation [20]. In contrast to porphyrins, phthalocyanines have not been as
studied in such reactions due to their more complicated syntheses. Phthalocyanines form HVMO
species upon reaction with peroxides, e.g., H2O2, TBHP and m-chloroperbenzoic acid (mCPBA)
[21-23]. The m-CPBA oxidant stands apart from other peroxides due to the complex reaction
2

mechanism and tendency to oxidize stereoselectively even under metal-free conditions although
low yields and conversion [24].
We have synthesized and characterized (E)-4-((2-morpholinoethyl)imini)methyl)phenoxy
substituted Co(II) and Cu(II) phthalocyanine complexes. Because the solubility of
phthalocyanines increases in organic solvents by using substituents such as alkyl, alkoxy,
aryloxy, and alkylthio chains and bulky groups, E-4-((2-morpholinoethyl)imini)methyl)phenoxy
groups have been used as substituents. Catalytic activities of Co(II) and Cu(II) phthalocyanine
complexes have been investigated for phenolic oxidation with different oxygen sources.
2. Experimental
The equipment, materials, general procedure and method for oxidation of phenolic compounds
are given as supplementary materials.
2.1. Synthesis
2.1.1.
(E)-4-((2-morpholinoethyl)imini)methyl)phenoxyphthalonitrile
(3).
4-Nitrophthalonitrile 2 (0.74 g, 4.27 mmol) and (E)-4-((2-morpholinoethyl)imini)methyl)phenol
1 (1.0 g, 4.27 mmol) in dry DMF (10 mL) were heated to 55 °C. After stirring for 15 min at
55 °C, finely ground anhydrous K2CO3 (1.767 g, 12.81 mmol) was added in small portions over
2 h with efficient stirring and degassed several times. The mixture was stirred at 55 °C under a
nitrogen stream for 3 days. Afterwards, the mixture was poured into 200 g of crushed ice-water
mixture and stirred for 2 h. The resulting brown solid was collected by filtration and washed with
ethyl alcohol and water in turn, and subsequently dried in vacuo. Yield: 1.09 g (71%), m.p. 72–
75 °C. FT–IR: υmax (cm-1) = 3236–3112–3089 (C–H aromatic), 2969–2924–2862 (CH2, CH3),
2232 (C≡N), 1660 (C=N), 1484, 1454, 1387, 1347, 1306, 1276, 1248, 1114, 1089, 951, 914, 878,
771, 661. 1H NMR (ppm, CDCl3): δ = 8.28 (d, 1H, CH=N), 7.98–7.63 (m, 3H, Ar–H), 7.29–7.10
(m, 3H, Ar–H), 3.89 (t, 2H, CH2-N=CH), 3.72 (m, 4H, CH2-O), 2.60 (t, 2H, CH2-N), 2.35 (m,
4H, CH2-N). 13C NMR (ppm, CDCl3): δ = 160.02 (C14), 156.46 (C13), 154.93 (C7), 136.16 (C18),
135.74 (C16), 132.16 (C8), 127.48 (C10), 125.64 (C17), 124.56 (C15), 123.46 (C9), 122.90 (C12),
122.14 (C11), 116.93 (C20), 115.63 (C21), 106.85 (C19), 66.25 (C1,C3), 60.18 (C6), 57.35 (C5),
56.73 (C2,C4). LC-MS/MS (ES+) m/z: Calculated: 360.41 Found: 399.52 [M+K]+.
3

2.1.2. General procedure for the syntheses of MPcs (4 and 5). The phthalonitrile derivative 3
(0.25 g, 0.693 mmol) was dissolved in 3 mL of dry n-pentanol under a blanket of nitrogen in a
well-stoppered Schlenk tube. Catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
and anhydrous metal salts (0.173 mmol) [CoCI2, 22.45 mg: 23.3 mg; CuCI2] were subsequently
added into the solution and the reaction mixture was refluxed at 160 °C for 8 h. After cooling to
room temperature, the reaction mixture was diluted and the product was precipitated by adding
10 mL of ethanol. The resulting precipitate was filtered off, washed with EtOH and H2O
separately and dried in vacuo. The crude products were purified by column chromatography on
aluminium oxide 90 active basic alumina. Figure 1 displays the synthetic route for the MPcs 4
and 5.
2.1.2.1. Cobalt(II) phthalocyanine (4). MPc 4 was synthesized by following the aforementioned
general procedure for MPcs. The crude blue product was purified by column chromatography on
basic alumina using chloroform:ethanol (98:2) as eluent. The extract was evaporated to dryness
and dried under vacuum to give blue 4. Yield: 124 mg (48%), m.p. >300 °C. FT–IR: υmax (cm-1)
= 3161–3046 (C–H aromatic), 2963–2915–2850 (CH2, CH3), 1635 (C=N), 1605 (C=C), 1532,
1455, 1432, 1366, 1314, 1228, 1093, 1049, 957, 863, 755. UV–Vis (chloroform), λmax, nm
(logε): 328 (4.32), 384 (3.55), 614 (3.92) and 676 (4.32). MALDI–TOF–MS m/z: Calculated:
1500.52, Found: 1518.53 [M+H2O]+.
2.1.2.2. Copper(II) phthalocyanine (5). Phthalocyaninato copper(II) derivative 5 was synthesized
by following the aforementioned general procedure for MPcs. The crude blue product was
purified by column chromatography on basic alumina using chloroform:ethanol (96:4) as eluent.
The extract was evaporated to dryness and dried under vacuum to give blue solid 5. Yield:
110 mg (42%), m.p. >300 °C. FT–IR: υmax (cm-1) = 3025, 3011 (C–H aromatic), 2973, 2816,
2809 (C–H aliphatic), 1643 (C=N), 1609 (C=C), 1575, 1503, 1482, 1432, 1383, 1239–1122–
1098–1050 957, 865, 732. UV–Vis (chloroform), λmax, nm (logε): 336 (3.88), 386 (4.10), 620
(3.50) and 680 (4.42). MALDI–TOF–MS m/z: Calculated: 1505.18, Found: 1523.17 [M+H2O]+.
4

3. Results and discussion
3.1. Synthesis and characterization
The synthetic pathways for (E)-4-((2-morpholinoethyl)imini)methyl)phenoxy substituted
phthalonitrile derivative 3 and corresponding metallophthalocyanines 4 and 5 are demonstrated
in figure 1. The synthesized new compounds 3-5 were characterized by using UV–Vis (for 4 and
1
5), H NMR and 13C NMR spectroscopies (for 3), LC-MS/MS (for 3), MALDI–TOF mass
spectral data (for 4 and 5) and FT–IR. The MPc complexes 4 and 5 were synthesized via
cyclotetramerization of 3 in the presence of the corresponding anhydrous metal salts (CoCI2 for
4; CuCI2 for 5) in dry n-pentanol as solvent and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as
strong base at 160 °C under nitrogen atmosphere. 4 and 5 were purified through column
chromatography on basic alumina. 4 and 5 were soluble in most common organic solvents such
as THF, CH2Cl2, CHCl3, DMF and DMSO due to the substituted groups.
The synthesis of 3 was achieved in 71% yield through base-catalyzed aromatic nitro
displacement of 4-nitrophthalonitrile 2 with (E)-4-((2-morpholinoethyl)imini)methyl)phenol 1 in
dry DMF by using anhydrous K2CO3 as the base. After synthesis of 3, the peak in the vibrational
spectra of 1 for the O–H vibrations at 3650 cm-1 disappeared and a new vibration was observed
at 2232 cm-1 belonging to the C≡N functionality, indicative of the formation of 3. Other
characteristic vibrations corresponding to aromatic CH stretchings at 3236–3112–3089 cm-1;
aliphatic CH stretches at 2969–2862 cm-1 are consistent with the assigned formulation. In the
1H NMR spectrum of 3, the signal associated with the O–H disappeared and new signals of the
aromatic ring protons at δ = 8.28, 7.98–7.63 and 7.29–7.10 ppm were observed for 3. Other
1H NMR signals are almost identical with 1. The presence of signals at δ = 115.82–115.45 ppm
13
(C≡N) in the C NMR spectrum of 3 proved the proposed structure. The mass spectrum of 3
was measured with electrospray ionization technique (ES+) showing the parent ion peak at m/z:
399.52 [M+K]+.
The disappearance of the C≡N vibration at 2232 cm-1 indicated the cyclotetramerization
of 3 into the metallophthalocyanines 4 and 5. Also shown was the presence of C=N vibrations of
the inner core of 4 and 5 at 1635 cm-1 for 4 and 1641 cm-1 for 5. Owing to the paramagnetic
1
13
nature of Co+2 and Cu+2, H and C NMR measurements of 4 and 5 cannot be taken [25]. The
mass spectra of 4 and 5 were measured with MALDI–TOF–MS and were in a good accord with
5

the proposed structures. Molecular ion peaks were observed at m/z = 1518.53 [M+H2O]+ for 4
and 1523.17 [M+H2O]+ for 5.
The electronic spectra of 4 and 5 displayed the best indications concerning the
characteristic B and Q bands of typical MPcs. The electronic absorption spectra of 4 and 5 were
measured in chloroform (figure 2). Metallophthalocyanine derivatives 4 and 5 showed B bands at
328 nm (logε = 4.32) and 384 nm (logε = 3.55) for 4, 336 nm (logε = 3.88) and 386 nm (logε =
4.10) for 5 and intense single Q bands with lower wavelength shoulders at 614 nm (logε = 3.92)
and 676 nm (logε = 4.32) for 4 and 620 nm (logε = 3.56) and 680 nm (logε = 4.42) for 5. These
results are in accord with MPcs in the literature.
3.2. Catalytic studies
The catalytic activities of Co(II) and Cu(II) phthalocyanine complexes were explored for
oxidation of substituted phenolic compounds. All the oxidation reaction data are given in tables 1
and 2. In experiments for 3 h oxidant and auxiliary chemicals on the conversion and yields were
investigated. Phenolic compounds can be turned into various organic compounds in oxidation
reactions. In this work, two fragments were determined due to attack by catalytically active
species. In blank reactions (using no catalysts or oxidants) no product was detectable (table 3),
showing that catalyst and oxidant are essential for the oxidation. The main product was
determined as 2,3-dichloro-1,4-benzoquinone and the side product was determined as 2,3-
dichlorobenzaldeyde in the oxidation of 2,3-dichlorophenol (figure 3). Influence of substrate,
catalysts and results for oxidation processes are demonstrated in table 1. According to the results
of this table, 4 demonstrated the highest activity and selectivity producing 2,3-dichloro-1,4-
benzoquinone as major product in 2,3-dichlorobenzaldehyde oxidation. The results of the
catalytic oxidation of phenolic compounds by H2O2 in the presence of 4 are shown in figure 4.
This figure shows that 2,3-dichlorophenol oxidation has higher total conversion than the other
substrates with catalyst 4.
As the other parameters were kept constant, the molar ratio was increased from 300–1000
to determine the influence on substrate to metal ion ratio. The reaction rate increased with
decreasing of the substrate/catalyst molar ratio (table 2) as expected. Substrate/catalyst ratio on
the oxidation gave the same main product with TON and TOF values (313 and 104.5 with 4).
6

To determine oxygen source effect, H2O2, TBHP, m-CPBA and air were used as
oxidants. The results in table 2 show that H2O2 was the best oxidant for 2,3-dichlorophenol
oxidation in the presence of 4. Moreover, TBHP and m-CPBA can serve as oxidants but low
conversions were observed for 4 and 5. The reaction color changed from light blue to brown
when we added TBHP or m-CPBA, suggesting that 4 was degraded immediately with TBHP or
m-CPBA [26, 27]. The catalytic activity studies for 4 and 5 using air displayed no formation of
products during the oxidation process (figure 5). To find the optimal reaction conditions,
oxidant/catalyst ratio was tested in 2,3-dichlorophenol oxidation. When the oxidant/catalyst ratio
was increased from 300/1 to 800/1, the rate of the reaction increased. In contrast, while the
catalytic oxidation was processing from 800/1 to 1200/1, the conversion decreased. At this stage,
it is possible that the coordination around the cobalt ion can change and produce inactive species
[28-30].
Oxygen activation in oxidation reactions is a challenging problem. Co(II) complexes are
involved in one-electron reduction of oxygen to form superoxo (Co(III)–) or peroxo derivatives
(Co(III)– –Co(III)) [31, 32]. V.N. Shishkin et al. reported that the cobalt complex with
4-octasulfophenyltetrapyrazinoporphyrazine (a ligand with pronounced electron-withdrawing
properties) catalyzes the reactions of thiourea and N,N'-dimethylthiourea with oxygen [33, 34].
The reaction occurs under mild conditions to form the corresponding urea and sulfur in high
yield. In our work, we studied the catalytic oxidation reactions of phenolic compounds with
different oxygen sources and activated oxygen.
Temperature was also tested, changing from 50 °C to 90 °C, the catalytic activity of 4
change little. When the temperature was fixed to 50 °C, the maximum total conversion was
obtained (87%) with 4. Therefore, 50 °C is the optimum temperature of 2,3-dichlorophenol
oxidation for 4 with TBHP in 3 h. We are interested in the transition metals that are used in
catalytic work. Despite metallophthalocyanines are flat, π-conjugated carbon systems, their
electronic properties are determined to a large extent by the central metal. The electronic
configuration of central metal can change the catalytic activity of the phthalocyanine complex.
The activity of metallophthalocyanines in oxidation follows the order CoPc>CuPc. It is known
that the catalytic performance of transition metal species depends on the outer d-electron density
[35].
7

Changes in the catalysts were monitored by UV–vis spectroscopy during the oxidation
reaction. Decompositon of Co(II) phthalocyanines frequently occurs with addition of an oxidant
[26-30, 35, 36]. Co(II) phthalocyanine in chloroform has distinctive sharp vibronic Q band due
to the monomer in the absence of oxygen source [37]. Before adding oxidant, characteristic sharp
Q band of Co(II) phthalocyanine is seen at 668 nm (figure 6). As the oxidation reaction proceeds,
this Q band shifts to 673 nm, broadens and disappears at the end of the reaction. Shifting from
668 to 673 nm attested to oxidation of Co(II)-Pc to Co(III)-Pc [38-40]. After 3 h, this oxidized
intermediate decomposed and there was no further conversion to products. As shown in figure 6,
as the reaction progresses, widening and disappearing of Q band are interpreted as in Co(II)
phthalocyanine [38-40].
Some previously reported catalysts are summarized in table 3. Different peripheral
groups substituting cobalt(II), iron(II), manganese(III) and copper(II) phthalocyanines were
investigated with 2,6-di-tert-butylphenol, 2,4,6-trichlorophenol, 2,4,5-trichlorophenol, 2,3,6-
trimethylphenol and p-nitrophenol oxidation [41-48]. In table 3, tetrasulfonated iron
phthalocyanine was used in trichlorophenol oxidation with H2O2. In the same work, 24%
reaction conversion was obtained in 24 h at 25 °C. According to table 3, two oxidations with
H2O2 were carried out for tetrasulfonated cobalt phthalocyanine and octacationic iron
phthalocyanine catalyst. The former employed 2,4,5-trichlorophenol oxidation for 24 h at 75 °C
with 67% conversion and the latter was trichlorophenol oxidation for 10 min at 25 °C with 6%
conversion. By comparing the catalyst in these reports, it is inferred that 4 will be an interesting
catalyst in 2,3-dichlorophenol oxidation. In our previous work, tetrasubstituted Co(II) and Fe(II)
phthalocyanine complexes were studied as catalysts in oxidation of phenolic compounds [26-30,
35, 36] with high conversion and selectivity of Co(II) phthalocyanine. But in this research we are
able to reach the highest product conversion and selectivity for Co(II) phthalocyanine with lower
temperature (50 °C) for 2,3-dichlorophenol oxidation.
4. Conclusion
Tetra
substituted
phthalocyanine
complexes
4
and
5
bearing
(E)-4-((2-
morpholinoethyl)imini)methyl)phenoxy units were synthesized. In order to verify 3-5, a
combination of spectral techniques such as MALDI–TOF mass spectral data, UV–Vis, FT–IR,
13
1H NMR and C NMR was used. MPcs 4 and 5 are soluble in most organic solvents and the
8

catalytic activity of CoPc 4 was examined for oxidation of 2,3-dichlorophenol using different
oxygen sources. CuPc 5 shows catalytic activity with 75% and 72% product selectivity for 2,3-
dichlorophenol and m-methoxyphenol oxidation. The results indicat that 4 showed activity for
oxidation of 2,3-dichlorophenol to the corresponding 2,3-dichloro-1,4-benzoquinone as major
product in 3 h at 50 C. The optimal conditions were also determined in 2,3-dichlorophenol
oxidation with 4. All the results indicated that 4 with catalytic oxidation was an efficient
technology for industrial waste application. Converting from environmentally harmful phenolic
compounds into less harmful oxidation products by CoPc 4 derivative makes this study
intriguing.
References
[1]
[2]
G. Busca, S. Berardinelli, C. Resini, L. Arrighi. J. Hazard. Mater., 160, 265 (2008).
F. Tzompantzi, Y. Pina, F. Mantilla, O. Aguilar-Martínez, F. Galindo-Hernández, X.
Bokhimi, A. Barrera. Catal. Today, 220–222, 49 (2014).
[3]
[4]
M. Niu, R. Zhu, F. Tian, K. Song, G. Cao, F. Ouyang. Catal. Today, 258, 585 (2015).
F. Shahrezaei, Y. Mansouri, A.A.L. Zinatizadeh, A. Akhbari. Powder Technol., 221, 203
(2012).
[5]
[6]
N. Kashif, F. Ouyang. J. Environ. Sci., 21, 527 (2009).
J. Gómez, A. Bódalo, E. Gómez, A. Hidalgo, M. Gómez, M. Murcia. Chem. Eng. J., 145,
142 (2008).
[7]
[8]
[9]
H. Ling, K. Kim, Z. Liu, J. Shi, X. Zhu, J. Huang. Catal. Today, 258, 96 (2015).
I. Ali, S.R. Kim, S.P. Kim, J.O. Kim. Catal. Today, 282, 31 (2017).
S.M.S. Chauhan, P. Kumari, S. Agarwa. Synthesis, 23, 3713 (2007).
[10] P.-C. Lo, X. Leng, D.K.P. Ng. Coord. Chem. Rev., 251, 2334 (2007).
[11] K.K. Yadav, S. Ahmad, S.M.S. Chauhan. J. Mol. Catal. A: Chem., 394, 170 (2014).
[12] A.B. Sorokin. Chem. Rev., 113, 8152 (2013).
[13] S.M.S. Chauhan, A. Kumar, K.A. Srinivas. Chem. Commun., 18, 2348 (2003).
[14] K.K. Yadav, S. Ahmad, U. Narang, S. Bhattacharya, S.M.S. Chauhan. ChemSelect, 1,
3635 (2016).
[15] W.N. Oloo, L. Que. Acc. Chem. Res., 48, 2612 (2015).
[16] K.P. Bryliakov, E.P. Talsi. Coord. Chem. Rev., 276, 73 (2014).
9

[17] D. Wang J. Liu Z. Liu. J. Solid State Chem., 251, 243 (2017).
[18] K. Ray, F.F. Pfaff, B. Wang, W. Nam. J. Am. Chem. Soc., 136, 13942 (2014).
[19] M. Costas. Coord. Chem. Rev., 255, 2912 (2011).
[20] P. Afanasiev, A.B. Sorokin. Acc. Chem. Res., 49, 583 (2016).
[21] H. Hussain, A. Al-Harrasi, I.R. Green, I. Ahmed, G. Abbas, N.U. Rehman. RSC Adv., 4,
12882 (2014).
[22] Y. Gök, S.Z. Gök, İ.Ü. Karayiğit. J. Organomet. Chem., 873, 43 (2018).
[23] D.S. Nesterov, O.V. Nesterova, M.N. Kopylovich, A.J.L. Pombeiro. Mol. Catal., 459, 8
(2018).
[24] O.V. Nesterova, M.N. Kopylovich, D.S. Nesterov. RSC Adv., 6, 93756 (2016).
[25] M.J. Stillman, T. Nyokong, in: C.C. Leznoff, A.B.P. Lever (Eds.), Phthalocyanines:
Properties and Applications, vol. 1, VCH, New York (1989).
[26] S. Gökçe, E.T. Saka, Z. Bıyıklıoğlu, H. Kantekin. Synth. Met., 176, 108 (2013).
[27] A. Aktaş, E.T. Saka, Z. Bıyıklıoğlu, I. Acar, H. Kantekin. J. Organomet. Chem., 745-746,
18 (2013).
[28] E.T. Saka, Z. Bıyıklıoğlu, H. Kantekin, I. Kani. Appl. Organomet. Chem., 27, 59 (2013).
[29] I. Acar, R. Bayrak, E.T. Saka, Z. Bıyıklıoğlu, H. Kantekin. Polyhedron, 50, 345 (2013).
[30] E.T. Saka, I. Acar, Z. Biyiklioğlu, H. Kantekin. Synth. Met., 169, 12 (2013).
[31] N.N. Kundo, N.P. Keier. Zh. Fiz. Khim., 42, 1352 (1968).
[32] B. Basu, S. Satapathy, A.K. Bhatnagar. Catal. Rev.: Sci. Eng., 35, 571 (1993).
[33] V.N. Shishkin, E.V. Kudrik, S.V. Makarov, G.P. Shaposhnikov. Kinet. Catal., 48, 660
(2007).
[34] E.V. Kudrik, A. Theodoridis, R. van Eldik, S.V. Makarov. Dalton Trans., 0, 1117 (2005).
[35] E.T. Saka, G. Çelik, G. Sarkı, H. Kantekin. J. Incl. Phenom..Macrocycl. Chem., 85, 161
(2016).
[36] E.T. Saka, Z. Biyiklioglu. J. Organomet. Chem., 745-746, 50 (2013).
[37] V.N. Nemykin, V. Ya Chernii. S.V. Volkov, N.I. Bundina, O.L. Kaliya, V.D. Li, E.A.
Lukyanets. J. Porphyrins Phthalocyanines, 3, 87 (1999).
[38] M. Özer, F. Yılmaz, H. Erer, I. Kani, O. Bekaroğlu. Appl. Organomet. Chem., 23, 55
(2009).
[39] N. Sehlotho, T. Nyokong. J. Mol. Catal. A: Chem., 219, 201 (2004).
10

[40] H. Turk, Y. Cimen. J. Mol. Catal. A: Chem., 234, 19 (2005).
[41] Y.T. Kopkallı, H. Turk. Turk. J. Chem., 20, 54 (1996).
[42] V.M. Kothari, J.J. Tazuma. J. Catal., 41, 180 (1976).
[43] B. Meunier, A. Sorokin. Acc. Chem. Res., 30, 470 (1997).
[44] M. Sanchez, N. Chap, J.-B. Cazaux, B. Meunier. Eur. J. Inorg. Chem., 7, 1775 (2001).
[45] B. Agboola, K.I. Ozoemena, T. Nyokong. J. Mol. Catal. A: Chem., 227, 209 (2005).
[46] T. Ichinohe, H. Miyasaka, A. Isoda, M. Kimura, K. Hanabusa, H. Shirai. React. Funct.
Polym., 43, 63 (2000).
[47] C. Pergrale, A.B. Sorokin. C.R. Acad. Sci. Ser. IIc Chim., 3, 803 (2000).
[48] A.D. Paola, V. Augugliaro, L. Palmisano, G. Pantaleo, E. Savinov. J. Photochem.
Photobiol. A, 155, 207 (2003).
11

Figure 1. Synthesis of precursor phthalonitrile compound 3 and MPcs 4 and 5. Reagents and
conditions: (i) dry DMF, K2CO3, 60 °C, 96 h; (ii) n-pentanol, DBU, 160 °C, CoCl2, CuCl2.
12

Figure 2. UV–Vis spectra of 1.00×10-5 M of complexes. Co(II)Pc, Cu(II)Pc in CHCl3.
13

Figure 3. The oxidation products of 2,3-dichlorophenol.
14

4-Nitrophenol
2-Chlorophenol
2,3-Dichlorophenol
3-Methoxyphenol
100
90
80
70
60
50
40
30
20
10
0
0
50
100
Reaction time (min.)
150
200
Figure 4. Time‐dependent conversion of phenolic compounds oxidation with H2O2 as an oxidant
for 4.
15

Catalyst 4
Catalyst 5
100
80
60
40
20
0
H2O2
TBHP
m-CPBA
air oxygen
Oxidant Type
Figure 5. The oxidant effect on 2,3-dichlorophenol oxidation [reaction conditions:
2,3-dichlorophenol (1.20×10-3 mol), Co(II)Pc and Cu(II)Pc (3.33×10-6 mol), oxidant
(2.66×10-3 mol), DMF (0.01 L), 3 h and 50 C].
16

Figure 6. Time-dependent changes in the visible spectrum of the oxidized complex 4 observed
on addition of TBHP (2.66×10-3 mol) to a reaction mixture containing 1.20×10-3 mol
2,3-dichlorophenol and 3.33×10-6 mol complex 4 catalyst in 10 ml: (e) 36 min; (d) 72 min;
(c) 108 min; (b) 144 min; (a) 180 min after addition of TBHP. All spectra for the oxidized
complex 4 were taken after sixfold dilution with acetonitrile. (f) Visible spectrum of (non-
oxidized) complex 4 in DMF.
17

Table 1. Oxidation of substituted phenols catalyzed by 4 and 5.
Total
conversion
(%)
Product
selectivity
(%)
TON
TOF
(h-1)
Substrate
Major product
4
5
4
5
4
5
4
5
O H
O
45
47
27
21
162
169
54
56
N O 2
O
O
O H
C l
73
87
84
65
66
48
76
92
79
63
72
75
263
313
302
234
237
173
87.6
78
C l
O
O
O H
C l
C l
104.5 79.2
C l
C l
O
O H
O
100.9 57.6
O
O C H 3
O C H 3
TON = mole of product / mole of catalyst
TOF = mole of product / mole of catalyst × time
Conversion was determined by GC.
Catalyst/substrate/oxidant ratio = 1/600/800, Reaction time = 3 h.
18

Table 2. Selective oxidation of 2,3-dichlorophenol with 4 and 5 using different oxidant and temperature.
Conversion
(%)
Selectivitya
(%)
TON
TOF (h-1)
Subs./Ox./Cat
Oxidant
Temperature (°C)
4
5
4
5
4
5
4
5
300/800/1
600/800/1
H2O2
H2O2
50
50
50
50
50
50
50
50
50
50
75
90
25
50
50
63
87
77
75
51
69
53
48
35
-
40
66
68
58
37
55
48
32
22
-
56
92
80
83
63
79
65
55
58
-
48
72
59
48
68
65
45
40
43
-
113
72
37.6
24
313 237 104.5 79.2
900/800/1
H2O2
416 367
540 418
183 133
248 180
190 172
173 115
138
180
61
122
139
44.4
60
57
38
26
-
1200/800/1
600/300/1
H2O2
H2O2
600/500/1
H2O2
82.8
63.6
57.6
42
600/1200/1
600/800/1
H2O2
m-CPBA
TBHP
Air oxygen
H2O2
600/800/1
126
-
79
-
600/800/1
-
600/800/1
87.3
86
43
-
44
40
25
-
91
90
55
-
65
52
31
-
313 158 104.5
309 144 103
53
48
30
-
600/800/1
H2O2
600/800/1
H2O2
155
90 52
600/800/free cat.
600/free ox./1
H2O2
-
-
-
-
-
-
H2O2
-
-
-
-
-
TON = mole of product / mole of catalyst
TOF = mole of product / mole of catalyst × time
Conversion was determined by GC.
Reaction conditions: 600/800/1: 1.20×10-3 mol) / 3.33×10-3 mol / 2.66×10-6 mol
a Selectivity of TMHQ, Reaction time = 3 h
19

Table 3. Catalytic activities towards the homogeneous oxidation of phenolic compounds of some previously
reported catalysts.
Reaction temp.
Reaction time
(h)
Conv.
(%)
Catalyst
CoPcTsa
FePce
CoPcd
Substrate
Oxidant
Ref.
(C)
DTBP
TCP
24
24
70
nrı
O2
66
85
[37]
KHSO5
[38, 39]
CoPcTsa
FePcTsb
CoPcd
CoPcTsa
FePcTsb
CuPcTsc
2,4,5-TCP
TMP
24
2
75
nrj
90
75
H2O2
O2
67
77
96
[40]
[40]
[41]
[42]
p-nitrophenol
DTBP
3
TBHP
TBHP
2
61
39
05
CoPcd
FePce
MnPcf
CuPcg
DTBP
3
30
TBHP
93
-
[43]
97
-
FePcTsb
TCP
TCP
24
10 min
3
25
25
90
H2O2
H2O2
24
6
[29]
[44]
[31]
FePcOCh
CoPcı
FePcı
p-nitrophenol
TBHP
97
75
a CoPcTs = tetrasulfonated cobalt phthalocyanine
b FePcTs = tetrasulfonated iron phthalocyanine
c CuPcTs = tetrasulfonated copper phthalocyanine
d CoPc = substituted cobalt phthalocyanine
e FePc = substituted iron phthalocyanine
f MnPc = substituted manganese phthalocyanine
g CuPcg = substituted copper phthalocyanine
h FePcOC = octa cationic iron phthalocyanine
j nr = not reported
20