Synthesis, characterization, and theoretical studies on some metallophthalocyanines with octakis phenoxyacetamide substituents

Article abstract of DOI:10.1080/15533174.2012.749897

The synthesis of substituted metallophthalocyanines bearing phenoxyacetamide moieties was achieved by cyclotetramerization of 1,2-bis(phenoxyacetamide)-4,5-dicyanobenzene in the presence of metal (Zn (4), Mg (5), Ni (6)) salts. These compounds were purifi

Full text of DOI:10.1080/15533174.2012.749897

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Synthesis, Characterization, and Theoretical Studies
on Some Metallophthalocyanines With Octakis
Phenoxyacetamide Substituents
a
a
M. Salih Ağırtaş & Selçuk Gümüş
a Department of Chemistry, Faculty of Sciences, Yüzüncü Yıl University, Van, Turkey
Version of record first published: 07 Mar 2013.
To cite this article: M. Salih Ağırtaş & Selçuk Gümüş (2013): Synthesis, Characterization, and Theoretical Studies on Some
Metallophthalocyanines With Octakis Phenoxyacetamide Substituents, Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry, 43:5, 628-634
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:628–634, 2013
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.749897
Synthesis, Characterization, and Theoretical Studies on
Some Metallophthalocyanines With Octakis
Phenoxyacetamide Substituents
M. Salih Ag˘ırtas¸ and Selc¸uk Gu¨mu¨s¸
¨ ¨
¨
Department of Chemistry, Faculty of Sciences, Yuzuncu Yıl University, Van, Turkey
phthalonitrile and diiminoisoindole. However, different synthe-
sis strategies have been used to prepared phthalocyanine deriva-
tives, which are mainly based on the periphery covalent linkings
by using functional groups.[1,10]
The synthesis of substituted metallophthalocyanines bearing
phenoxyacetamide moieties was achieved by cyclotetramerization
of 1,2-bis(phenoxyacetamide)-4,5-dicyanobenzene in the presence
of metal (Zn (4), Mg (5), Ni (6)) salts. These compounds were pu-
rified by several techniques such as crystallization, column chro-
matography, and wash with different solvents. The new compounds
Our continuing efforts on the synthesis of novel phthalocya-
nines with macrocyclic substituents have enabled us to reach
products with hexadeca tert-butyl,[11] phenoxyacetamide,[12]
macrocycles. The nature of substituents can strongly influence
the essential parameters of a phthalocyanine, such as its solubil-
ity, thermal stability, electronic absorption, and chemical sens-
ing properties. In the present article, we report the synthesis,
electronic, and thermal properties of metallophthalocyanines
bearing octakis phenoxyacetamide substituents.
1
were characterized by elemental analysis, IR, H-NMR, and UV-
Vis spectral data. The ground-state geometries of the complexes
were optimized using density functional theory (DFT) methods at
B3LYP/6-31G (d, p) level. The results of thermal analysis of novel
phthalocyanines 4–6 have also been reported herein.
Keywords DFT, metal complexes, phenoxyacetamide, phthalocya-
nines, phthalonitrile, thermal stability
EXPERIMENTAL
INTRODUCTION
Electronic spectra were recorded on a Hitachi U-2900 Spec-
trophotometer (Van YYU, Central Laboratory, Turkey). Routine
IR spectra were recorded on a Mattson 1000 FTIR spectrometer
(Van YYU, Central Laboratory, Turkey) in KBr pellets. Melting
points were measured on an electrothermal apparatus. 1H NMR
spectra were recorded on a Varian Mercury 200 MHz spectrom-
eter (Trabzon KTU Central Laboratory, Turkey) with tetram-
ethylsilane as internal standard. Elemental analyses results were
found in good agreement with calculated values. Thermal ex-
perimental was performed in a SETARAM TG/DTA/DSC-16
instrument (Van YYU, Central Laboratory, Turkey). All other
reagents and solvents were of reagent-grade quality and were
obtained from commercial suppliers. All solvents were dried
and purified as described by Perrin and Armarego[13] and the
solvents were stored over molecular sieves (4 Å).
Phthalocyanine is an intensely blue-green–colored macro-
cyclic compound that is widely used in dyeing.[1–3] Phthalocya-
nines form coordination complexes with most elements of the
periodic table. These complexes are also intensely colored and
also are used as dyes or pigments.
Phthalocyanines have been investigated for many decades as
active components in such diverse fields as media for optical data
storage, electrochromic, optical limiting devices, multistage-
redox-dependent fluorophores, photosensitisers, chemical in-
ertness, very high thermal stability, electrical conductivity,
photoconductivity, catalytic activity, and medicinal therapeu-
tic agents.[4–8] Moreover, phthalocyanine compounds have been
investigated as donor materials in molecular electronics (e.g., or-
ganic field-effect transistors[9] and metal phthalocyanines have
long been examined as catalysts for redox reactions). Areas of
interest are the oxygen reduction reaction and the sweetening of
gas streams by removal of hydrogen sulfide.
Preparation of 1, 2-Bis (phenoxyacetamide)-4,
5-dicyanobenzene (3)
Phthalocyanine forms upon heating phthalic acid derivatives
that contain nitrogen functional groups. Classical precursors are
4,5-dichloro-1, 2-dicyanobenzene (0.985 g, 0.005 mol) was
dissolved in dimethyl sulfoxide (DMSO) (20 cm3) under ni-
trogen atmosphere and 4-acetamidophenol (1.51 g, 0.01 mol)
was added. After stirring for 15 min at room temperature, finely
ground anhydrous potassium carbonate (2.8 g, 0.02 mol) was
added in portions in a 2-h period with efficient stirring. The re-
action mixture was stirred under nitrogen at room temperature
Received 31 March 2012; accepted 29 October 2012.
Address correspondence to M. Salih Ag˘ırtas¸, Department of Chem-
istry, Faculty of Sciences, Yu¨zu¨ncu¨ Yıl University, 65080, Van, Turkey.
E-mail: salihagirtas@hotmail.com
628

METALLOPHTHALOCYANINES
629
FIG. 1. B3LYP/6-31G(d) optimized structures of the three metallocyanines and a representative side view (color figure available online).
for 24 h. Then, the mixture was poured into 200 mL water, and the product. The reaction mixture was precipitated by adding
precipitate was filtered off, washed successively with water and EtOH. The precipitate was filtered and washed with EtOH. Com-
little acetone, and dried in vacuo (50◦C). The yield was 1.55 g pound 4 is soluble in DMF, DMSO.
(72.7%). Anal. Calcd. (%) for C24H18N4O4: C, 67, 60; H, 4.25;
The yield of compound 4: 0.030 g (27.27%). Anal. Calcd.
N, 13, 14. Found (%): C, 67, 57; H, 4.27; N, 13, 15. IR spectrum for C96H72N16O16Zn: C, 65, 10; H, 4.10; N, 12, 65%. Found: C,
(cm−1): 3298, 3069, 2864, 2802, 2232, 1666, 1590, 1253, 1016, 65, 12; H, 4.08; N, 12, 64%. IR spectrum (cm−1):3259, 1667,
854, 506. 1H NMR (DMSO-d6) δ, ppm: 8.08(NH), 7.78–7.17 1503, 1202, 889, 661, 448, UV-vis (DMF) λmax nm (log ε):
(Ar-H), 2.35(CH3).
682(4.85), 617(3.65).
Preparation of
Preparation of octaphenoxyacetami-
octaphenoxyacetamidephthalocyaninatozinc (II) (4)
dephthalocyaninatomagnesium (II) (5)
Compound 3 (0.106 g, 0.25 mmol) and excess ZnCl2 were
Compound 3 (0.106 g, 0.25 mmol) and excess MgCl2.6H2O
powdered in a quartz crucible and heated in a sealed glass tube were powdered in a quartz crucible and heated in a sealed glass
for 7 min under nitrogen atmosphere at 330◦C. After cooling tube for 7 min under nitrogen atmosphere at 330◦C. After cool-
to room temperature, a green-colored reaction product was ob- ing to room temperature, a green-colored reaction product was
tained. The product was washed with water, EtOH, acetone, obtained. The product was washed with EtOH, CHCl3, and
THF. DMF (2 mL) was added to the residue in order to dissolve ethyl acetate. DMF (2 mL) was added to the residue in order

˘ ¨ ¨
M. S. AGIRTAS¸ AND S. GUMUS¸
630
to dissolve the product. The reaction mixture was precipitated NiCl2 metal salts under nitrogen atmosphere (Scheme 1). The
by adding EtOH. The precipitate was filtered and washed with metal coordinates with four equivalents of the ligand to give
EtOH. Compound 5 is soluble in DMF, DMSO.
the final corresponding metallophthalocyanine. Melting points
The yield of 5: 0.022 g (20.37%) Anal. Calcd. (%) for of the compounds 4–6 were found to be higher than 300◦C.
C96H72N16O16Mg : C,66,65; H,4.19; N,12,95. Found (%): C, Moreover, solubility tests revealed that these phthalocyanines
66, 66; H, 4.17; N, 12, 96. IR spectrum (cm−1): 3260, 1723, 4–6 are not soluble in common solvents but soluble in DMF and
1503, 661, 449. UV-Vis (DMF) λmax nm (log ε):680(5.24), DMSO.
614(4.41), 360(4.45).
Spectral data of the synthesized compounds are consistent
with the proposed structures. Comparison of the IR spectral data
clearly indicated the formation of compound 3 by the appearance
of new absorption bands at 3297–3267 cm−1 (NH), 2232 cm−1
(CN), 1666–1590 cm−1 (C C), 1204 cm−1 (Ar-O-Ar). Af-
ter conversion of the compound 3 into the phthalocyanines
(4–6), the sharp peak for the CN vibration around 2232 cm−1
disappeared.
Preparation of
octaphenoxyacetamidephthalocyaninatonickel (II) (6)
Compound 3 (0.106 g, 0.25 mmol) and excess NiCl2 were
powdered in a quartz crucible and heated in a sealed glass tube
for 7 min under nitrogen atmosphere at 330◦C. After cooling
to room temperature, a green-colored reaction product was ob-
tained. The product was washed with EtOH, hot EtOH, and
THF. DMF (2 mL) was added to the residue in order to dissolve
the product. The reaction mixture was precipitated by adding
EtOH. Compound 6 is soluble in DMF and DMSO.
The yield of 6: 0.025 g (22.72 %). Anal. Calcd. (%) for
C96H72N16O16Ni : C,65,35; H,4.11; N,12,70. Found (%): C, 65,
33; H, 4.13; N, 12, 72. IR spectrum (cm−1): 3294, 1665, 1502,
1399, 1252, 1013, 847, 507. UV-Vis (DMF) λmax nm (log ε):
673(5.06), 637(5.00), 346(518), 336(5.21), 320(5.22).
1
The H NMR spectrum of 3 exhibited NH at 10.08(s, 2H),
aromatic protons at 8.05 (dd, J = 8.73, Ar-H), 7.71 (s, Ar-H),
7.70(s, Ar-H), 7.66 (dd, J = 8.73, Ar-H),7.31 (dd, J = 8.73,
Ar-H), 7.11 (dd, J = 8.73, Ar-H), and 2.03 (s, 6H, -CH3).
The geometry optimized structures and the Mulliken
charge[17] distribution in the heart of the present complexes are
shown in Figures 1 and 2, respectively. The complexes are com-
puted to be square planar at the phthalocyanine moiety; however,
the phenoxyacetamide substituents were oriented perpendicular
to the main plane and got almost parallel positioning to one
another. One phenoxyacetamide aligned up in the space the
other down such that the steric hinderence have been minimized
and the most stable ground state structures have been obtained.
As seen in Figure 2 the net charges on Zn, Mg, and Ni are 1.022,
COMPUTATIONAL DETAILS
The molecular structures were geometry optimized using
density functional theory at B3LYP/6-31G (d, p) level with
no symmetry constrains. The Gaussian 03 package program
has been used during all computational calculations.[14] The
vibrational analysis for each metal complex does not yield any
imaginary frequencies, which indicates that the structure of each
molecule corresponds to at least a local minimum on the poten-
tial energy surface. The normal mode analysis was performed
for 3N−6 vibrational degrees of freedom, N being the number
of atoms forming the system.
The time-dependent density functional theory (TD-DFT) cal-
culation has been used to compute the vertical excitation ener-
gies, oscillator strengths (f), and excited state compositions in
terms of excitations between the occupied and virtual orbitals
for metal complexes.[15,16] In this study, the TD-DFT method
with the same basis set has been performed to obtain absorp-
tion wavelengths and the oscillation strength (f) within visible
to near-UV region. For the goal of approaching available ex-
perimental results, we have performed 100 allowed transitions
(nstates = 100) in our TD-DFT calculation process.
RESULTS AND DISCUSSION
Our key starting compound 3 was obtained by the re-
action between 4,5-dichloro-1, 2-dicyanobenzene 2 and 4-
acetamidophenol 1 in dry dimethylsulfoxide (DMSO) in the
presence of dry K2CO3. The synthesis of metal complexes 4–6
have been achieved by heating 3 with ZnCl2, MgCl2.6H2O and
FIG. 2. Mulliken charge distribution for Zn, Mg, Ni metallocyanines, respec-
tively (color figure available online).

METALLOPHTHALOCYANINES
CH3
NH
631
O
CH3
NH
O
O
CN
CN
Cl
Cl
CN
CN
O
i
2
+
OH
3
1
2
HN
H3C
ii
O
CH3
NH
O
O
CH3
HN
HN
O
CH3
O
CH3
NH
O
O
O
O
O
N
M
N
N
N
N
N
N
N
O
H
O
H3C
O
O
N
HN
H3C
O
NH
HN
H3C
O
4
5
6
M : Zn Mg Ni
H3C
O
SCH. 1. The route for the synthesis of metallophthalocyanines.
1.258, and 0.885, respectively, being lower than the formal
charge +2. It is a consequence of charge donation from coordi-
nating nitrogen atoms. All donor atoms of the ligands possess
negative charge development. The coordinating nitrogen atoms
are almost twice more negative than the connecting nitrogen
atoms, which might be a result of absence of imino hydrogen
atom. The expected –1 formal charge on these atoms decreased
absolutely to –0.687 (–0.750 and –0.672) upon coordination to
the corresponding positively charged metal atom.
The UV–vis spectra of the phthalocyanine 4–6 in DMF
showed characteristic Q band absorptions between 673 and
682 nm, which were attributed to the π-π∗ transition from the
highest occupied molecular orbital (HOMO) to the lowest un-
occupied molecular orbital (LUMO) of the Pc ring. The other
bands (B) in UV region at 346–360 nm were observed due to
transition from the deeper π levels to the LUMO (Figure 3).
FIG. 3. Absorption spectrum of 4–6 in DMF.

˘
¨
¨
632
M. S. AGIRTAS¸ AND S. GUMUS¸
FIG. 4. The molecular orbitals involved in electronic transitions (color figure available online).
The spectra showed monomeric behavior evidenced by a single ergies indicate HOMO and LUMO to be responsible for these
Q band, typical of metallated phthalocyanines compounds for bands. Three-dimensional HOMO and LUMO energy schemes
4–6 in DMF which depict the monomeric nature of the these are shown in Figure 4. The carbon atoms of the central periphery
complexes in this solvent.[18] Geometry optimized structures contribute most to HOMOs of the complexes; however, contri-
have been subjected to TD-DFT calculations with the same butions from outer atoms cannot be ignored. On the other hand,
basis set to predict electronic spectra. Transition energies and LUMOs of the three systems are mainly composed of both
molecular orbital energies and schemes have been predicted for the carbon and nitrogen atoms of the phthalocyanine moiety
singlet state excitations. The characteristic bands appeared at together with some contribution form the metal atoms in the
668–680 nm for the series 4–6. Calculated molecular orbital en- cases of Zn and Ni.

METALLOPHTHALOCYANINES
633
TABLE 1
Thermal properties of compounds 4–6
organic groups, octakis phenoxyacetamide substituted phthalo-
cyanine complexes 4–6 are found to be thermally more stable.
Thus, phenoxyacetamide groups on phthalocyanine ring have
a stabilizing effect on the thermal property. In conclusion, the
phthalocyanines reported in this work can be considered as ef-
ficient candidates for potential applications that require thermal
durability.
Compound
Initial dec temp (a˚C)
Main dec. temp (a˚C)
4
5
6
400
370
410
610
680
620
CONCLUSIONS
In the present study, the synthesis of Zn, Mg, and Ni metal-
lophthalocyanines with octakis phenoxyacetamide substituents
have been reported. The structural characterizations of the com-
pounds have been performed by various spectroscopic data.
Additionally, some structural and electronic information ob-
tained from theoretical calculations at the level of B3LYP/6-
31G (d, p) have been revealed. Theoretical calculations indi-
cated that the substituents oriented perpendicular to the main
plane to minimize the steric repulsion. Last, the results of the
thermal analysis showed that these novel complexes are more
durable at higher temperatures than their previously reported
counterparts.
It is well known that phthalocyanines exhibit excellent ther-
mal stability. According to thermal analyses, temperatures of
450–600◦C are the limit of thermal treatment under inert
gas.[19,20] The thermal properties of the octakis phenoxyac-
etamide substituted phthalocyanine derivatives 4–6 were in-
vestigated by thermogravimetric analysis. The initial and main
decomposition temperatures are given in Table 1.
Phthalocyanine derivatives 4–6 substituted octakis phenoxy-
acetamide groups, showed a weight loss corresponding to mois-
ture at 100–140◦C. The initial and extensive decompositions
occur at ca. 410–420◦C and 610–680◦C. The thermal decompo-
sition of 4 in nitrogen atmosphere was observed to be very
slow. 17% mass loss of compound 4 was found at 1095◦C
(Figure 5). Moreover, mass losses of 7% and 49% were ob-
served for 5 and 6, respectively. These temperatures are higher
than those found for different organic substituted groups con-
taining phthalocyanine complexes.[21] Thus, the substitution of
phthalocyanine core with phenoxyacetamide groups increases
the thermal stability of the present phthalocyanines complexes
4–6 significantly, when compared with other phthalocyanines
substituted with different organic groups.
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