Photo-physico-chemical properties of 1,3-benzenediol-substituted face-to-face phthalocyanines

Article abstract of DOI:10.1016/j.ica.2020.119830

Here, we report the synthesis of new ball-type phthalocyanines that are symmetrically substituted with Mg–Mg, Zn–Zn, and Co–Co centers and contain four 1, 3-benzenediol substituents at the beta positions. The structures and photophysical properties, including the fluorescence quantum yield, triplet quantum yield, and photochemical properties with singlet oxygen quantum yield, of these compounds were investigated. Moreover, the applicability of these molecules as photosynthesizers in cancer nanomedicines is discussed. Furthermore, the photodegradation quantum yield of the complexes with the inclusion of Co binuclear phthalocyanine was examined, and their fluorescence and triplet lifetimes were studied in dimethyl sulfoxide. The obtained Uv–Vis spectra exhibited unexpected results; for instance, H₂Pc exhibited a broad and peculiar Q band with D4h symmetry. Moreover, H₂Pc was found to have a triplet lifetime of 460 μs whereas ZnPc had a higher triplet lifetime of 1100 μs.

Full text of DOI:10.1016/j.ica.2020.119830

InorganicaChimicaActa511(2020)119830
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Research paper
Photo-physico-chemical properties of 1,3-benzenediol-substituted face-to-
face phthalocyanines
Mevlüde Canlıca
Chemistry Department, Inorganic Chemistry Division, Yıldız Technical University, Davutpasa Campus, 34220 Esenler, Istanbul, Turkiye
A R T I C L E I N F O
A B S T R A C T
Keywords:
Here, we report the synthesis of new ball-type phthalocyanines that are symmetrically substituted with Mg–Mg,
Zn–Zn, and Co–Co centers and contain four 1, 3-benzenediol substituents at the beta positions. The structures
and photophysical properties, including the fluorescence quantum yield, triplet quantum yield, and photo-
chemical properties with singlet oxygen quantum yield, of these compounds were investigated. Moreover, the
applicability of these molecules as photosynthesizers in cancer nanomedicines is discussed. Furthermore, the
photodegradation quantum yield of the complexes with the inclusion of Co binuclear phthalocyanine was ex-
amined, and their fluorescence and triplet lifetimes were studied in dimethyl sulfoxide. The obtained Uv–Vis
spectra exhibited unexpected results; for instance, H2Pc exhibited a broad and peculiar Q band with D4h
symmetry. Moreover, H2Pc was found to have a triplet lifetime of 460 µs whereas ZnPc had a higher triplet
lifetime of 1100 µs.
Ball-type phthalocyanine
Face-to-face interaction
Fluorescence quantum yield
Singlet oxygen quantum yield
Triplet life time
1. Introduction
exhibits unique spectroscopic properties such as a broad Q band. Later,
the Bekaroglu group focused on the electrochemical properties of ball-
Phthalocyanines (Pcs) were accidentally discovered in 1907 [1] and
first characterized in the 1930s [2,3]. Since then, they have attracted a
great deal of attention by researchers worldwide. Pcs are stable aro-
matic macrocyclic compounds with 18-π electron conjugated systems,
which enables strong absorption in the red region of the visible spec-
trum. There are many potential applications of Pcs in chemical sensors,
liquid crystals, optical data storage, and as carrier or generation ma-
terials in near-infrared devices [4,5].
Furthermore, Pc derivatives containing metal ions, such as Zn and
Mg, show promise for second-generation photosensitizers for use in
photodynamic therapy (PDT) for cancer [6,7]. In PDT, photosensitizer,
vis ible light and oxygen as singlet oxygen (1O2) and triplet oxygen
(3O2) are used to induce a photodynamic effect that damages the living
tissue in the target region. An ideal photosensitizer exhibits strong
absorption in the wavelength range of 670–800 nm. In addition, as
molecular oxygen plays an important role in the photodynamic effect of
Pcs, the singlet oxygen quantum yield of the photosensitizer is of par-
ticular significance in PDT. However, researchers have yet to identify
an optimal photosensitizer that can be utilized as a light-sensitive drug
for alternative cancer treatments.
type Pcs including the nonlinear optical properties. Generally, their
ultraviolet–visible light (Uv–Vis) spectra differ from those of monomers
in that they exhibit high B bands and broad Q bands. In addition, the
Uv–Vis spectra often reveal noteworthy interactions between the Pc
rings or the two metal centers and substituents. However, in one study,
ball-type H2Pc was compared with metalPcs but was not found to ex-
hibit the necessary properties for use as a photosensitizer [6]. To date,
other studies of ball-type MgPc and H2Pc derivatives with various
substituents provide limited information about the photochemical be-
haviors of ball-type Pcs [11–27].
Other binuclear Pcs include clamshell-type Pcs (i.e., co-facial Pcs),
including 1,8-Naphthalene and 1,8-Anthracene [28] exhibit both
magnetic circular dichroism (MCD) and electrochemical properties.
Kobayashi et al. extensively reported the synthesis of binuclear ball-
type Pcs and their MCD properties [29,30] Seotsanyana [31] reported
the photochemical properties of such molecules and demonstrated that
they can be used as possible photosensitizers for PDT. Hence, both ball-
type and clamshell-type Pcs are of interest in terms of face-to-face in-
teraction although each Pcs are different structurally in that ball-type
Pcs has four substituent while clamshell Pcs has only one substituent. As
far as I know, nevertheless, the photochemical behaviors of neither ball-
type Pcs nor clamshell Pcs as being ball-type Pcs have not been widely
studied [9–39]. As O. Bekaroglu reported the synthesis of the ball-type
To date, several types of Pcs with various properties have been in-
vestigated [8]. One type of binuclear Pc is the ball-type Pc, which was
first synthesized by the Zefirove group in 2002 [9,10]. This ball-type Pc
E-mail address: mcanlica@yildiz.edu.tr.
https://doi.org/10.1016/j.ica.2020.119830
Received 7 May 2020; Received in revised form 10 June 2020; Accepted 10 June 2020
Availableonline12June2020
0020-1693/©2020PublishedbyElsevierB.V.

M. Canlıca
InorganicaChimicaActa511(2020)119830
Pcs are difficult but has their remarkable properties [26]. In the lit-
erature there still are limited papers any information about comparing
of the results which obtained with any properties of ball-type Pcs based
on face-to-face interaction effect.
The IR spectra of 3 clearly exhibit a ─C^N vibrational peak at
2235 cm−1. After conversion into Pcs, this characteristic ─C^N stretch
disappeared from the spectrum, which confirms that metalled- and
metal-free Pcs were formed. The remaining IR spectra for compound 3
and those of 4–7 were quite similar in that they exhibited Ar-O-Ar peaks
at 1247, 1083, 1094, 1124, 1089 cm−1, respectively.
The aim of this study is to synthesize metal-free, magnesium, zinc
and cobalt ball-type Pcs bearing 1,3-benzenediol moieties and in-
vestigate their photo-physico-chemical behaviors. The centers and
substituents of these molecules can be modified to manipulate the π-
electron conjugated ring system and intramolecular π- π* interactions
in the interest of making them more suitable for PDT. For example, an
ideal Type II-photosensitizer should exhibit a relatively long triplet
state lifetime (τT, microsecond range) [6]. It is also important to con-
sider the fluorescence quantum yield (ΦF), triplet quantum yield (ΦT),
singlet oxygen quantum yield (ΦΔ) photodegradation quantum yield
(Φd), fluorescence lifetime (τF) and triplet lifetime (τT) in order to de-
sign a suitable sensitizer. Moreover, the MCD properties of the syn-
thesized ball-type Pcs are evaluated.
The 1H NMR spectra of 3 and 4–6 in DMSO were difficult to in-
terpret but confirmed that presence of aromatic protons in the aromatic
region as expected. The 1H NMR spectra of 4–6 show that the aromatic
protons were present at concentrations of almost 6.50–8.50 ppm, which
is attributed to the 1,3-benzenediol substitution in the ball-type com-
plexes. On the other hand, the inner protons of the H4Pc2 ring were not
observed as reported previously. Moreover, the obtained peaks were
very broad, which is typical of face-to-face complexes [37].
The complexes were further characterized by MALDI-MS using 2,5-
dihydroxy benzoic acid as the matrix, which is known to intensify the
fragmentation process [41]. Compounds 4–7 exhibited complicated
spectra due to the presence of mixed isomers of these complexes. In the
positive-ion and negative-ion MALDI-MS spectra of purified 4–7 (Fig.
S1, supplementary information), the protonated, molecular ion peak
and fragment ions as adducted Li and H2O were observed [27]. This
indicates that leaving groups are available for complexes 4 and 5 under
the MALDI matrix conditions.
Pcs generally have two characteristic bands: a low-intensity B band
between 300 and 400 nm and a relatively intense Q band in the range of
600–800 nm with a molar absorptivity often exceeding 10─5 L mol−1
cm−1 due to the π–π* transition from the macrocyclic structure. The Q
band is also accompanied by one or two weak vibronic bands (Qvib). For
ball-type Pcs, the intensity of the B band is typically higher than that of
the Q band, possibly due to intramolecular interactions between the Pc
rings.
2. Results and discussion
Phthalonitriles widely used as the starting material due to their high
yields for the desired Pc complexes [40]. Here, a diphthalonitrile, 4-
nitrophthalonitrile, was used to synthesize ball-type Pcs according to
the simplified preparation and purification methods that were devel-
oped previously as shown in Scheme 1. Ball-type Pcs were obtained in a
low yield from 4, 4′-(1,3-phenylenebis (oxy)) diphthalonitrile, 3.
Complexes 4–7 were purified by column chromatography on silica gel
using chloroform (CHCl3), tetrahydrofuran (THF), methanol (MeOH)
and dimethyl sulfoxide (DMSO), respectively, as the mobile phase. The
structures and purities of the H2–, Mg-, Zn- and Co- Pc derivatives were
confirmed by Uv–Vis, 1H nuclear magnetic resonance (NMR), Fourier
transform infrared (FT-IR) spectroscopy and mass spectrometry and
elemental analyses.
As shown in Fig. 1, in DMSO, complexes 4–7 exhibit approximately
10−5 M of Q band absorption at 682, 670/702, 680, and 672 nm,
Scheme 1. i: DMSO, 7 days, K2CO3 ii: n-pentanol, DBU, reflux, overnight, metal salt.
2

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InorganicaChimicaActa511(2020)119830
Fig. 1. Ground-state electronic absorption spectra for 4–7 plotted on the same axes.
recorded from the same solution at the same time; those of complex 6
are shown in Fig. 2 (others are shown in Fig. S2, supplementary data).
Table 2 summarizes the measured MCD and Uv–Vis absorption data.
The MCD spectra exhibit dispersion-type signals with peaks and troughs
at + 617, +677 and − 692 nm for 4, +600, −657 and − 691 nm for
5, +619, +676 and − 690 nm for 6, +607 and − 646/−665 nm as
shoulders and −684 nm for 7, corresponding to the Q band absorption.
Complexes 4–7 exhibited cross-over points at 683, 628, 681, and
641 nm, respectively. These points describe the Q band maxima for
ball-type complexes 4 and 6 and are related to the main π-π* excited
state, which retains its orbital degeneracy and results in curve splitting
with the Faraday A term. Excited state degeneracy was also observed in
B band region with cross-over points at 347, 329, 349, and 333 nm,
respectively.
The MCD spectra of complexes 5 and 7 are relatively similar in
shape in the Q band region and can explain the behaviors of the ag-
gregated Pcs [37], as noted previously by Kobayashi. Further, the ball-
type MCD spectra exhibited similarities with those of co-facial binuclear
molecules, which indicates the occurrence of face-to-face interactions.
The absorption and fluorescence excitation spectra of complex 6 in
DMSO are shown in Fig. 3 (the others are shown in Fig. S3, supple-
mentary information). The excitation, absorption, and emission spectral
data are listed in Table 1. Fluorescence emission peaks were observed at
691 nm for 4, 707 nm for 5, and 690 nm for 6. While complexes 4 and 6
exhibited typical behaviors, complex 5 had some abnormal properties,
which may be explained by its tendency to aggregate in this solvent.
The Stokes shifts for 4–6 were 9, 35, 11 nm, respectively [45,27].
Further, Mg2Pc2 again exhibited different behavior, which can be at-
tributed to the polarity of the singlet state.
Table 1
Uv–Vis absorption (Q band), emission and excitation spectral data, and pho-
tophysical and photochemical data for the phthalocyanines complexes in
DMSO.
Complex λmax
(nm)
4
5
6
7
λAbs (logε)*a
682(3.79) 691 670/
702(4.31)
680(4.61) 690 672(4.62) …
λEms
707
701
35
0.06
0.65
0.54
0.40
0.83
2.2
λExc
683
9
681
11
…
…
…
…
…
…
…
0.107
….
ΔλStokes
ΦF
0.06
0.43
0.27
0.67
0.63
1.38
5.34
460
0.04
0.33
0.72
0.24
2.18
2.88
2.89
1100
ΦT*b
ΦΔ
ISC
SΔ
Φd(x10-6)
τF (ns)
τT (µs)
4.49
110
[a] log ε: dm3. moL;−1cm−1
[b] Excitation λmax: 663, 671, and 662 for 4–6, respectively.
.
respectively, as summarized in Table 1; further, their molar absorp-
tivities were calculated as 3.79 for H4Pc2, 3.91 for Mg2Pc2, 4.62 for
Zn2Pc2 and 4.78 for Co2Pc2. Unexpectedly, B band of complex 6 was
lower than that which is typical of ball-type Pcs, which may be due to
the Zinc metal ion. Complex 4 has a broad single Q band that is typical
of metalled Pc complexes with D4h symmetry. In contrast, the absorp-
tion of complex 5 resembles that of a metal-free Pc. These findings
provide evidence that both metalled and metal-free Pcs had aggregated
in the solution [42,43]. The aggregated complexes exhibited both broad
The fluorescence quantum yield, ΦF values are typical of MPc
complexes [27]. The ΦF values are 0.060, 0.064, and 0.043 in DMSO for
4–6, respectively. Low ΦF values are often predicted for aggregated
MPcs.31 This result may be attributed to the fact that 1,3 benzenediol
groups showing the interaction between the two rings were minimal
The complexes generally had lower fluorescence quantum yields cor-
responding to higher triplet quantum yields. Fluorescence lifetimes are
Q
vib and a shoulder on the high-energy side of the Q band, which can be
attributed to intramolecular interactions. The fact that a split Q band is
observed for metalled species but not metal-free species confirms that
intramolecular coupling occurred between the two halves of the bi-
nuclear complexes as reported in other studies [44,31,33–36].
The absorption and MCD spectra for complexes 4–7 in DMSO were
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Fig. 2. The ground-state electronic absorption spectrum of MCD and ball-type ZnPc in DMSO.
5.34 ns for 4, 4.49 ns for 5 and 2.89 ns for 6 [46]. These values show
the effect of the Pc skeleton and decrease due to atom effect.
The obtained triplet quantum yield (ΦT) and lifetime (τT) data of the
complexes are shown in Table 1. The high triplet state quantum yield
values in DMSO are 0.43, 0.65 and 0.33 for 4–6, respectively. The
values of ΦT values suggest more efficient intersystem crossing (ISC) in
the presence of the 1, 3-benzenediol substituents for substituted com-
plexes, corresponding to low ΦF values. This data of complexes are
lower when compared to those of ball-type Pcs in the same solvent as
described in a previous study.
A triplet decay curve of the change in absorbance (ΔA) versus time
(in seconds) was obtained experimentally and used to derive the triplet
4

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InorganicaChimicaActa511(2020)119830
Generally, high triplet oxygen quantum yields in Pc complexes are ac-
companied by high singlet oxygen quantum yield; the complex 6 which
is among the complexes 4–6 synthesized in this study exhibited higher
singlet oxygen quantum yield. This may indicate that the complexes
have ball-type structures with face-to-face interactions.
Overall, the SΔ values in Table 1 show that singlet oxygen is gen-
erated efficiently in DMSO. The high SΔ values for complexes 4–6 may
be due to the interaction between the two rings. The SΔ value for
complex 6 was the largest and that of 5 was the lowest. This trend can
be attributed to the lifetimes of the triplet states.
In order to evaluate the stabilities of these derivatives under singlet
oxygen attack due to intense light exposure, the photodegradation
quantum yields (Φd) of complexes 4–7 were measured in DMSO by
monitoring the photo-induced decomposition in terms of the decrease
in the intensity of the Q band under irradiation over 60 min. The
photodegradation spectrum for complex 7 is shown in Fig. 6 (those of
complexes 4–6 are shown in Fig. S6, supplementary information) and
the results are summarized in Table 1. The peak absorbance of complex
7 decreased and blue-shifted by 9 nm in the presence of light as ob-
served under heating in DMSO. After accounting for the effects of the
differences in the maximum wavelength of the Q band on the starting
maximum wavelength, the order of stability of the substituted com-
plexes in DMSO was 6 > 5 > 4 > 7. The data further indicates that
the molecules are highly stable in the solvent that was used [48,49].
Table 2
Ground-state electronic absorption and MCD spectral values for ball-types
phthalocyanines for 4 to 7 in DMSO.
B/nm
Qvib/nm
Q00/nm
4 H2Pc
ABS
MCD
5 MgPc
ABS
MCD
6 ZnPc
ABS
MCD
7 CoPc
ABS
346
…
…
−374
616
+617
680
+677
…
−692
330
+324
…
−356
616
+600
665
−657/-691
696
−743
349
+339
…
−371
616
+619/+635
678
+676
…
−690
333
+313
…
−347
614/631
+607
672
−646/−665
…
−684
MCD
lifetime. A typical triplet state decay curve for Zn2Pc2 is shown in Fig. 4
(those of the other complexes are shown in Fig. S4, supplementary in-
formation). The obtained lifetimes were 460, 110 and 1100 μs for 4–6,
respectively. The triplet lifetime of complex 6 was the longest, which
may be attributed to the interactions between the two rings. These
results show that Pcs with 1,3-benzenediol substituents in the same
position but bearing different metals in the central cavity also exhibit
different triplet lifetimes and quantum yields.
Next, the spectral changes were observed during the photolysis of
the complexes in the presence of DPBF were measured over time (0–140
sec) by Uv–Vis spectroscopy; the experimental results for complex 6 are
shown in Fig. 5 (those of the other complexes are shown in Fig. S5,
supplementary information) and the data are summarized in Table 1.
The spectra show no changes in the Q band intensities, confirming that
the complexes are not degraded in the singlet oxygen studies [47,31].
The ΦΔ values for 4–6 were 0.27, 0.54 and 0.72, respectively.
3. Conclusions
In this study, novel ball-type Pcs were successfully synthesized and
characterized. Pcs were found to be prone to aggregation in solution.
All complexes studied exhibited spectroscopic similarities in that they
had monomeric structures and were either metal-free or metalled
complexes, demonstrating that the present work may be useful as a
model method. Further, the obtained spectra of aggregated Pcs confirm
Fig. 3. Absorbance (dashed line), excitation (solid line) and emission (pink dotted line) spectra of complex 6 in DMSO; excitation λmax: 611 nm. (For interpretation of
the references to colour in this figure legend, the reader is referred to the web version of this article.)
5

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InorganicaChimicaActa511(2020)119830
Fig. 4. Mono-exponential triplet decay curve for 6 in DMSO.
that their properties were similar to those previously described in the
literature [38,42,45]. This observation may be explained by orbital
degeneracy due to symmetric changes in the shapes of the Q bands for
H4Pc2 and Mg2Pc2 in DMSO. All of the compounds exhibited low
fluorescence quantum yields and high triplet quantum yields. More-
over, Zn2Pc2 exhibited high singlet oxygen quantum yield. The photo-
degradation quantum yields of all complexes showed that the molecules
are highly photostable in the solvent used. Although all complexes were
found to have good triplet lifetimes, that of Zn2Pc2 indicated it to be
superior to the others. The photo-physico-chemical behaviors of these
complexes, and particularly those of Zn2Pc2, were found to be suitable
for PDT. Another interesting finding was that Co2Pc2 underwent a blue
shift when exposed to light and heat; this would be an interesting topic
of further research.
The results presented here for benzene-1,3-diol (A) were compared
with those reported in an unpublished paper with the same substituent,
catechol(benzene-1,2-diol (B) [50], and a different substituent con-
taining a carboxyl group in the peripheral position, catechol-4-car-
boxylic acid (C) [27]. The Q band maximum wavelengths of these Pcs
in DMSO were similar to each other [55,61,45,51]. The Q band was not
split at 684 nm for the 1,2-benzene or at 682 nm 1,3-benzene in H4Pc2
while that of catechol-4-carboxylic acid at 675/702 nm was split as
Fig. 5. Time-dependent photobleaching of DPBF absorption in the presence of 6 in DMSO.
6

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InorganicaChimicaActa511(2020)119830
Fig. 6. Absorbance spectra for complex 7 during photodegradation in DMSO.
expected for H4Pc2. On the other hand, Mg2Pc2s was split at 670/
702 nm for 1,3-benzene, at 670/701 nm for 1,2-benzene, and at 668/
698 nm for catechol-4-carboxylic acid. This result may be attributed to
the intramolecular coupling of ball-type Pcs (A). However, the effects of
the substituent were not observed for Co2Pc2 and Zn2Pc2 at 672 and
680 nm, respectively. The triplet lifetimes of MgPcs were consistent:
110, 110, and 130 µs for A, B, and C, respectively. However, the triplet
lifetimes of Zn2Pc2s differed: 1100, 440 and 60 µs for A, B, and C, re-
spectively. Finally, the singlet oxygen quantum yields of the Zn2Pc2s
were 0.21, 0.35, and 0.01 for A, B, and C, respectively. Considering this
data, it could be said that the carboxyl group decreases the photo-
chemical properties of ball-type Pcs. Further, it is important to note that
ball-type ZnPcs exhibited good singlet oxygen quantum yields, making
them promising candidates as photosensitizers. On the other hand, I
believe that the present paper will be remarkable in that it report both
the photochemical and MCD properties of ball-type Pcs all at once.
2235 (C^N), 1587/1593 (C]C), 1310/1285/1247 (CeOeC). 1H NMR
(DMSO‑d6), δ (ppm): 8.14 (2H, d, Ar–H), 7.93 (2H, d, Ar–H), 7.61 (H, t,
Ar–H), 7.56 (H, d, Ar–H), 7.57 (H, d, Ar-H) 7.15 (2H, s, Ar–H), 7.14 (H,
s, Ar-H). Anal. calcd. for C22H10N4O2 C, 72.92; H, 2.78; N, 15.46, found
C, 72.65; H, 2.29; and N, 15.75%. LC-MS, m/z anal. calcd. 362.34,
found [M]+: 362.09, and [M + H2O]+: 380.12.
Typical Synthesis Procedures for Ball-Type Pcs 4–7: Under Ar
gas without metal salt, an excess of magnesium(II) chloride (0.050 g,
0.52 mmol), zinc(II) acetate (0.050 g, 0.23 mmoL) and cobalt(II)
acetate (0.050 g, 0.20 mmol) was added to a solution of diphthaloni-
trile, 3 (0.100 g, 0.28 mmoL) in 4 mL of n-pentanol and stirred for
2–3 min. at reflux temperature. Then, ten drops of DBU were added to
form ball-type binuclear H4Pc2, Mg2Pc2, Zn2Pc2, and Co2Pc2. The re-
action was monitored by Uv–Vis spectroscopy and TLC over the course
of 20 h. After the reaction was complete, the mixture was cooled to
room temperature and the excess n-pentanol was removed under re-
duced pressure. The crude product was washed with methanol. Then, a
large amount of water was added before the produced was purified by
silica gel column chromatography using a gradient of CHCl3, THF,
MeOH, DMSO, then DMSO + HCI as the eluents. The ball-type Pcs were
obtained as a deep green powder that has a melting point above 250 °C
and is soluble in THF, DMSO, and DMF.
Synthesis and Purification of Ball-type H2Pc (4): Complex 4 was
synthesized and purified as described above in the general procedure,
without any metal salt and using only compound 3 directly. The reac-
tion conditions and amounts were as outlined above. The yield was
0.032 g or 32%. Uv–Vis (DMSO), λmax (nm): 682, 621. FT-IR (ATR)
(µmax/cm−1): 3296 (Ar–CH), 2238 (CN), 1717 (CO), 1596 (C]C), and
1121/1083 (CeOeC). 1H NMR (DMSO‑d6), δ (ppm): 7.85–7.00 (44H,
Ar-H). Anal. calcd. for C88H44N16O8: C, 72.72; H, 3.05; N, 15.42, found:
C, 72.51; H, 3.42; and N, 15.85%. MALDI-TOF-MS, m/z calcd. 1453,39,
found 1453.47 [M] + .
4. Materials and methods
Previously reported materials, equipment and methods were used in
this study [11–27] to synthesize ball-type derivatives 4–7 from 4, 4′-(1,
3-phenylenebis (oxy)) diphthalonitrile (3) using n-pentanol in the pre-
sence of DBU at the reflux temperature as shown in Scheme 1.
Synthesis of 4, 4′-(1, 3-phenylenebis (oxy)) diphthalonitrile (3)
[52]: Compound 2 (1.272 g) was dissolved in dry DMSO (10 mL) and
compound 1 (4.00 g, 28.90 mmol) was added under inert atmosphere.
Finely ground anhydrous potassium carbonate (8.00 g) was added to
this reaction mixture and stirred for 10 h at 70 °C. After stirring at room
temperature for 7 days, the reaction was monitored by thin layer
chromatography (TLC) as it proceeded under Ar. Finally, the reaction
mixture was poured onto ice and crystalized from ethanol to form a
light yellow precipitate. The pure product was dried using P2O5 under a
vacuum for 15 days. The yield was 2.80 g or 70%. The following FT-IR
(ATR) signals were observed (υmax/cm−1): 3120/3093/3074 (Ar–CH),
Synthesis and Purification of Ball-type MgPc (5): Complex 5 was
synthesized and purified as described above in the general procedure
7

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InorganicaChimicaActa511(2020)119830
using magnesium (II) chloride. The reaction condition and amounts
were as outlined above. The yield was 0.012 g or 12%. Uv–Vis (DMSO),
λmax (nm): 702, 670, 618, 331. FT-IR (ATR) (µmax/cm−1): 3070
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://
doi.org/10.1016/j.ica.2020.119830.
(Ar–CH), 1720 (CO), 1594 (C]C), and 1266/1255/1094 (CeOeC). 1
H
NMR (DMSO‑d6), δ (ppm): 7.90–7.05 (40H, Ar-H). Anal. calcd. for
C
88H40N16O8Mg2: C, 70.56; H, 2.69; N, 14.96, found: C, 70.41; H, 2.43;
References
and N, 15.02%. MALDI-TOF-MS, m/z calcd. 1497.97, found 1546.97
[M + 2Na + 3H].
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outlined above. The yield was 0.029 g or 27%. Uv–Vis (DMSO), λmax
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CRediT authorship contribution statement
Mevlüde Canlıca: Methodology, Project administration, Resources,
Software, Supervision, Visualization, Writing - original draft, Writing -
review & editing.
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Declaration of Competing Interest
The authors declare that they have no known competing financial
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Acknowledgments
This work was supported by the Research Fund of the Yildiz
Technical University (Project No: 2012-01-02-KAP12), Tubitak-BİDEB-
2219 International Postdoctoral Research Scholarship Programme,
Number: 1059B191401081, and the Yildiz Technical University in
Istanbul, Turkey, the University of Illinois at Urbana-Champaign in the
USA, and Rhodes University in Grahamstone, South Africa. The author
is thankful to Prof. Kenneth K. Suslick for providing lab space to syn-
thesize the compounds used in this study. The author is also grateful to
Prof. Tebello Nyokong for providing the funds and lab facilities for
conducting the photophysical and photochemical measurements.
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8