Synthesis, photophysical and photochemical properties of metal-free and zinc(II) phthalocyanines bearing α-naphtholbenzein units

Article abstract of DOI:10.1016/j.jorganchem.2014.05.015

Synthesis of metal-free and zinc (II) phthalocyanine complexes bearing α-naphtholbenzein units was described. Precursor required for the preparation of phthalocyanine complexes was prepared by nucleophilic aromatic substitution reaction between 4-nitropht

Full text of DOI:10.1016/j.jorganchem.2014.05.015

Accepted Manuscript
Synthesis, photophysical and photochemical properties of metal-free and zinc(II)
phthalocyanines bearing α-naphtholbenzein units
Mukaddes Özçeşmeci
PII:
S0022-328X(14)00243-5
10.1016/j.jorganchem.2014.05.015
JOM 18587
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 10 February 2014
Revised Date: 12 May 2014
Accepted Date: 15 May 2014
Please cite this article as: M. Özçeşmeci, Synthesis, photophysical and photochemical properties of
metal-free and zinc(II) phthalocyanines bearing α-naphtholbenzein units, Journal of Organometallic
Chemistry (2014), doi: 10.1016/j.jorganchem.2014.05.015.
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Graphical Abstract Synopsis
The synthesis, characterization, photophysical and photochemical properties of
phthalocyanines bearing α-naphtholbenzein units were described. The effect of the
concentration on the aggregation and solvent effects on the absorption spectra of
phthalocyanines were investigated. The fluorescence of the phthalocyanines was effectively
quenched by 1,4-benzoquinone (BQ) in tetrahydrofuran.

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Graphical Abstract Pictogram

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Synthesis, photophysical and photochemical properties of metal-free and
zinc(II) phthalocyanines bearing α-naphtholbenzein units
Mukaddes Özçeşmeci a,*
a Department of Chemistry, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey
Abstract
Synthesis of metal-free and zinc (II) phthalocyanine complexes bearing α-naphtholbenzein units
was described. Precursor required for the preparation of phthalocyanine complexes was prepared
by nucleophilic aromatic substitution reaction between 4-nitrophthalonitrile and α-
naphtholbenzein. Cyclotetramerization reactions of the new dinitrile derivative were
accomplished in dry dimethylformamide at refluxed temperature. The new compounds were
characterized by using elemental analyses, proton and carbon nuclear magnetic resonance, fourier
transform infrared spectroscopy, ultraviolet–visible spectroscopy, fluorescence spectroscopy and
mass spectrometry. The photophysical and photochemical properties of metal-free and zinc (II)
phthalocyanines were studied in tetrahydrofuran. The fluorescence of the phthalocyanine
complexes was effectively quenched by 1, 4-benzoquinone (BQ) in tetrahydrofuran. The effect of
the concentration on the aggregation properties and solvent effects on the absorption spectra of
phthalocyanine complexes were also investigated.
Keywords: Phthalocyanines; synthesis; α-naphtholbenzein; aggregation; solvent effect;
fluorescence.
* Corresponding author. Tel: +90 212 285 7308; Fax: +90 212 285 6386
E-mail: selcukoglu@itu.edu.tr (M. Ozcesmeci)
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1. Introduction
Phthalocyanines (Pcs) and related compounds have attracted significant interest because
of their potential applications in fields such as active materials for liquid crystals [1],
electrochromic devices [2], nonlinear optics [3], organic electronics [4], gas sensors [5], solar
cells [6], electrocatalytic reagents [7], and PDT (cancer therapy) [8].
Although MPc complexes have been extensively studied, their properties cannot be fully
exploited as they have low solubility in most organic solvents and they tend to aggregate.
Aggregation is a very common phenomenon in Pcs due to the intermolecular interactions
between the macrocycles, which minimizes their technological applications. The nature of the
substituents is important not only in terms of the solubility of Pcs but also in the context of the
state of their aggregation in solution as well as their physical and photophysical properties [9].
The most effective strategy to avoid aggregation involves the use of bulky substituents, which
can induce severe steric crowding adjacent to the phthalocyanine core [10–14]. Substitution of
functional groups also changes the electron density of the macrocycle and finds its use in various
fields. Condensed multicyclic aromatic compounds (e.g., naphthalene, pyrene derivatives) are
functional groups effective in photoemission studies [15–18]. Introducing these groups into Pcs
may have a profound effect on their applications in energy transfer processes.
α-Naphtholbenzein is a pH indicator that changes colour when the neutral solution
becomes alkaline. Although there were several studies including the α-naphtholbenzein in the
literature [19–22], there is no study which has been done about Pcs with α-naphtholbenzein.
Encouraged by this information, herein, we report the preparation, photophysical and
photochemical properties of new Pcs containing α-naphtholbenzein groups on the peripheral
positions. The influence of the substituent on the phthalocyanine framework, central metal ion
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(metal-free or zinc), concentration and solvent effect on the absorption spectra were also
investigated.
2. Experimental
2.1. Materials
All reagents and solvents were of reagent grade quality obtained from commercial
suppliers. Silica gel (Kieselgel 60, 200-400 mesh) was used in the separation and purification of
compounds by column chromatography. The homogeneity of the products was tested in each step
by TLC (SiO2). All reactions were carried out under nitrogen atmosphere in dried solvents. The
solvents were stored over molecular sieves (4 Å). 4-nitrophthalonitrile was synthesized according
to published methods [23].
2.2. Equipment
IR spectra were recorded on a Perkin-Elmer Spectrum One FT-IR spectrometer with ATR
capability, electronic spectra were recorded on a Scinco SD 1000 single beam ultraviolet-visible
(UV-vis) spectrophotometer using 1 cm path length cuvettes at room temperature. Fluorescence
spectra were recorded on a Perkin-Elmer LS55 fluorescence spectrophotometer. Mass spectra
were performed on Bruker Microflex MALDI-TOF/MS and Perkin-Elmer Clarus 500 mass
13
spectrometers. Proton and carbon nuclear magnetic resonance (1H NMR and C NMR) spectra
were recorded on an Agilent VNMRS 500 MHz spectrometer using TMS as internal reference.
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Melting points were determined on a Büchi Melting Point B-540 apparatus. Elemental analyses
were performed on a Thermo Flash EA 1112.
2.3. Synthesis
2.3.1. Synthesis of (Z)-4-((5-((4-oxonaphthalen-1(4H)-ylidene)(phenyl)methyl)naphthalen-1-
yl)oxy)phthalonitrile (1)
α-Naphtholbenzein (1.081 g, 2.890 mmol) and 4-nitrophthalonitrile (0.500 g, 2.890
mmol) were stirred and dissolved in 50 mL dry DMF at room temperature. Anhydrous K2CO3
(0.800 g, 5.780 mmol) was added portionwise over 2 h under a nitrogen atmosphere, then the
reaction mixture was stirred vigorously for further 3 days. After reaction completed, the mixture
was poured into 200 mL water. The precipitate formed was filtered off, washed with water until
the filtrate was neutral. The product was purified by column chromatography with silica gel using
chloroform as eluent. Yield: 0.607 g (42%). Anal. calcd. for C35H20N2O2: C, 83.98; H, 4.03; N,
5.60%. Found: 84.02; H, 4.04; N, 5.58%. IR: νmax, cm-1 3061 (Ar-CH), 2228 (C≡N), 1639 (C=O),
1
1590 (C=C), 1242 (C-O-C). H NMR (CDCl3): δ, ppm 8.22 (d, Ha), 8.08 (d, Hb), 7.97 (d, Hc),
7.94 (s, Hd), 7.81 (t, He), 7.79 (d, Hf), 7.65 (t, Hg), 7.55 (d, Hh), 7.50 (d, 2Hi), 7.45-7.39 (m, 7Hj),
7.34 (m, Hk), 7.16 (d, Hl), 6.94 (d, Hm), 6.57 (d, Hn). 13C NMR (CDCl3): δ, ppm 184.80 (C1),
161.61 (C2), 150.29 (C3), 149.68 (C4), 143.22 (C5), 135.74 (C6), 135.67 (C7), 135.12 (C8), 131.82
(C9), 130.81 (C10), 130.39 (C11), 129.48 (C12), 129.48 (C13), 129.33 (C14), 128.39 (C15), 128.13
(C16), 128.13 (C17), 127.88 (C18), 127.60 (C19), 127.10 (C20), 126.51 (C21), 126.31 (C22), 126.31
(C23), 125.50 (C24), 123.16 (C25), 121.81 (C26), 121.71 (C27), 121.68 (C28), 121.22 (C29), 117.81
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(C30), 115.71 (C31), 114.90 (C32), 113.52 (C33), 109.54 (C34), 109.51 (C35). MS (MALDI-TOF):
m/z 538.78 [M+K]+.
2.3.2. Metal-free phthalocyanine (2)
A mixture of compound 1 (0.2 g, 0.39 mmol) and two drops of 1.8-
diazabicyclo[5.4.0]undec-7-ene (DBU) in 2 mL of dry DMF were heated and stirred at refluxed
temperature in a glass sealed tube for 36 h under nitrogen atmosphere. After cooling to room
temperature the green crude product was precipitated with water and then dried in vacuo. Finally,
the solid product was chromatographed on column chromatography which is placed silica gel
using CHCl3:ethylacetate (1:4) as the eluent. Yield: 0.05 g (25%). Anal. calcd. for C140H82N8O8:
C, 83.90; H, 4.12; N, 5.59%. Found: 83.65; H, 4.10; N, 5.60%. IR: νmax, cm-1 3061 (Ar-CH),
1619 (C=O), 1597 (C=C), 1233 (C-O-C). 1H NMR (CDCl3): δ, ppm 8.27-6.57 (br, 80H, Ar-H), -
4.15 (bs, 2H,-NH). UV-vis (THF): λmax, nm (log ε) 339 (4.50), 668 (4.51), 700 (4.54). MS
(MALDI-TOF): m/z 2005.49 [M+1]+, m/z 1648.36 [[M+1]-C27H17O]+, m/z 1291.59 [[M+1]-
2C27H17O]+.
2.3.3. Zinc(II) phthalocyanine (3)
Compound 1 (0.2 g, 0.39 mmol) and Zn(CH3COO)2 (0.018 g, 0.1 mmol) were heated in
dry DMF (1.5 mL) to reflux. This mixture was kept refluxing for 24 h under nitrogen atmosphere.
The mixture was cooled down to room temperature and the solid product was precipitated by
adding water. The green product was isolated by silica gel column chromatography first with
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CHCl3 and then with CHCl3:ethylacetate (1:4) as the eluent. Yield: 0.076 g (37%). Anal. calcd.
for C140H80N8O8Zn: C, 81.33; H, 3.90; N, 5.42%. Found: 81.55; H, 3.92; N, 5.39%. IR: νmax, cm-1
1
3063 (Ar-CH), 1620 (C=O), 1595 (C=C), 1231 (C-O-C). H NMR (CDCl3): δ, ppm 8.15-6.57
(br, 80H, Ar-H). UV-vis (THF): λmax, nm (log ε) 349 (4.87), 678 (5.07). (MALDI-TOF): m/z
2067.3 [M]+.
3. Results and discussion
3.1. Synthesis and characterization
The starting phthalonitrile derivative was prepared by a aromatic nucleophilic substitution
reaction between 4-nitrophthalonitrile and α-naphtholbenzein at room temperature under nitrogen
atmosphere in dry DMF in the presence of K2CO3 as a base (Scheme 1). This reaction has been
used in the preparation of a variety of ether or thioether substituted phthalonitriles [24–27].
Cyclotetramerization of the phthalonitrile derivative (1) to the metal-free phthalocyanine
(2) was accomplished in dry DMF in the presence of a few drops of 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) as a strong base at refluxed temperature in sealed tube.
The zinc(II) phthalocyanines (3) was obtained by the anhydrous Zn(CH3COO)2 in dry DMF
13
(Scheme 1). FT-IR, 1H NMR, C NMR, UV–vis, elemental analysis, and mass characterization
techniques were used to illuminate the structure of the novel compounds (1–3). Spectral data of
the novel compounds were similar to the expected structures.
In FT-IR spectra of phthalonitrile derivative 1, aromatic CH peaks were observed at above
3060 cm-1. Also, vibrations corresponding to C=O, C=C, and ether groups (C-O-C) at 1639,
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1590, and 1242 cm-1, respectively. In addition, the characteristic vibration of the C≡N appears at
2228 cm-1, after conversion of the dinitrile into the phthalocyanine, the sharp peak for the C≡N
vibration completely disappeared. Pcs 2-3 also have very similar IR absorptions for the peripheral
substituents.
1
In H-NMR analysis of 1 in CDCl3, aromatic protons appear at between 8.22–6.57 ppm.
13
The C NMR spectral data of 1 are also in accordance with the excepted structure. The carbon
resonances of the aromatic groups appear at between 161.61–109.51 ppm, C=O group appear at
184.80 ppm, C=C groups appear at 130.39 and 127.60 ppm, the other chemical shifts belonging
to nitrile carbons appear at 115.71 and 114.90 ppm, respectively (Numbering of the protons (Ha-n)
and carbon atoms (C1-35) in compound 1 used for NMR assignment is shown in Scheme 1). The
1H NMR spectra of the 2-3 are almost identical with compound 1, but rather broad, owing
probably to the aggregation of the Pcs which is frequently encountered at the concentrations used
for NMR spectroscopy. Another reason is that the mixed of positional isomers which are
expected to show chemical shifts that differ slightly from each other [28]. The inner NH protons
1
of 2 were also identified in the H NMR spectra with a broad chemical shift at - 4.15 ppm as a
consequence of the 18 π-electron system of the Pc ring.
In the MALDI-TOF mass spectrum of 1, the presence of the characteristic molecular ion
peak at m/z = 538.78 [M+K]+ confirmed the proposed structure. In the case of 2, in addition to the
[M+1]+ peak at m/z = 2005.49, fragment ions corresponding to the loss of [[M+1]-C27H17O]+ at
1648.36 and [[M+1]-2C27H17O]+ at 1291.59 were easily identified. Also, the molecular ion peak
for compound 3 found at m/z = 2067.3 [M]+. The elemental analysis were satisfactory.
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3.2. Ground state electronic absorption spectra
The UV-Vis spectra of the Pc complexes showed characteristic absorption in the Q band
region at 668 and 700 nm for 2 and 678 nm for 3. The B band region observed at 339 nm for 2
and 349 nm for 3. The metal-free derivative 2 gave doublet Q band as a result of the D2h
symmetry. The absorption spectrum of α-naphtholbenzein is dominated by three intense bands
with maximum absorption wavelength at 279, 308 and 430 nm. After conversion into Pc
derivatives, soret band of complexes 2 and 3 overlap with the absorption of α-naphtholbenzein
units at around 340–350 nm (Fig. 1).
It has been well established that non-aggregated Pcs are extremely important for their
various applications [29–33]. In this study the aggregation behaviour of 2 and 3 has been studied
by concentration-dependent UV-Vis spectra measurements in THF. The shape of the spectra
remained constant and their molar extinction coefficients obeyed the Beer-Lambert law in wide
range of concentration from 4x10-5 mol dm-3 to 5x10-6 mol dm-3 (insert in Fig. 2) for 2 and 5x10-5
mol dm-3 to 5x10-6 mol dm-3 for 3 (insert in Fig. 3), probably due to the bulky nature of the ring
substituents.
The compounds 2 and 3 had the best solubility in a number of organic solvents, such as
dichloromethane (DCM), dimethylformamide (DMF), dimethylsulfoxide (DMSO) and
tetrahydrofuran (THF) but compound 2 was hardly soluble in ethyl acetate and toluene.
In this study, solvent dependence of absorption spectra of compounds 2 and 3 were also
studied in different organic solvents (Fig. 4 and Fig. 5). It is obvious that the Q band position
changes with respect to the solvent. In Fig. 6, is shown the solvent dependence of Q bands of two
complexes as a function of solvent’s refractive index suggested by Bayliss [34]. Both the
complexes show the same tendency in that their Q band appears at a longer wavelength in a
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solvent with increasing refractive index. The red shift of the Q band increased in the following
order for 2 and 3: ethyl acetate < THF < DCM < DMF < DMSO < toluene. The positions of the
Q bands in these solvents show almost a linear dependence on this function. This suggests that
controls the “red shift” caused by interaction between the solvent molecules.
3.3. Fluorescence spectra
The fluorescence spectra of the phthalocyanine derivatives (2 and 3) were studied in THF,
upon excitation at the 645 nm for 2 and excitation at the 615 nm for 3 (Fig. 7). Emission at 708
nm for 2 and 688 nm for 3, occurred almost entirely from the phthalocyanine moiety (Table 1)
[35]. The emission spectrum of 3 is 11 nm red shifted when compared to the un-substituted
zinc(II)phthalocyanine complexes [36, 37]. The observed Stokes shifts (~8–11 nm) were within
the region observed for Pc complexes [11, 38]. Excitation spectrum of compound 2 show two
shoulder in the Q band and emission maxima of 2 come outs at lower energy than those of the
corresponding zinc(II)phthalocyanine (3). It means that metal-free phthalocyanine (2) shows red
shift in emission maxima compared to zinc (II)phthalocyanine (3) because of symmetry lowering
[17]. The excitation spectra of compound 3 was similar to absorption spectra and both were
mirror images of the fluorescent spectra in THF. The proximity of the wavelength of each
component of the Q-band absorption to the Q-band maxima of the excitation spectra for 3 suggest
that the nuclear configurations of the ground and excited states are similar and are not affected by
excitation in THF [39].
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3.4. Photophysical and photochemical properties
3.4.1. Fluorescence quantum yields and fluorescence lifetimes
The fluorescence quantum yields (ΦF) of the phthalocyanine derivatives (2 and 3) were
studied in THF. Fluorescence quantum yields (ΦF) were determined by the comparative method
(Eq. (1)) [40],
(1)
where F and FStd are the areas under the fluorescence curves of the zinc phthalocyanines and the
standard, respectively. A and AStd are the respective absorbances of sample and standard at the
excitation wavelengths and η and ηStd are the refractive indices of solvents used for the sample
and standard, respectively. ZnPc was employed as a standard in DMF (ΦF = 0.23) [41]. Both the
sample and the standard were excited at the same wavelength. Radiative or natural lifetimes (τo)
were estimated using PhotochemCAD program which uses the Strickler-Berg equation [42].
Finally, the fluorescence lifetimes (τF) were calculated using the following equation (Eq. (2)):
(2)
The fluorescence quantum yields were calculated as 0.19 for 2 and 0.27 for 3. ΦF values
of 2 is lower than unsubstituted ZnPc (ΦF = 0.25) [36], but ΦF values of 3 is higher than
unsubstituted ZnPc (Table 2) in THF. The increasing in the ΦF values for compound 3 in the
presence of the α-naphtholbenzein units suggests that the substituents less quench on the excited
singlet state [43]. The ΦF values of compound 3 are higher than for compound 2 [44].
Fluorescence quantum yield (ΦF) values of studied Pcs (2 and 3) are almost similar values
compared to metal free and zinc phthalocyanine derivatives studied in the literature [45].
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Fluorescence lifetime (τF) refers to the average time a fluorophore stays in its excited state
before fluorescing, and its value is directly related to that of fluorescence quantum yield. The
nature and the environment of a fluorophore determine its fluorescence lifetime [46]. The
fluorescence lifetimes (τF) were calculated using the Strickler-Berg equation (Eq. 2). Using this
equation, a good correlation has been found for the experimentally and theoretically determined
fluorescence lifetimes for the unaggregated compounds [37]. As stated above the aggregation was
not observed in all studied phthalocyanines in THF, so the values obtained using this equation are
a good measure of fluorescence lifetimes in this study. The τF values of the Pcs (2 and 3) (0.11
and 1.28 ns, respectively) are lower compared to unsubstituted ZnPc complexes in THF [36],
suggesting more quenching by substitution. The natural radiative lifetime (τo) of Pcs (2 and 3) are
shorter when compared to unsubstituted ZnPc in THF and the kF values of studied Pcs (2 and 3)
are higher than unsubstituted ZnPc in THF (Table 2).
3.4.2. Fluorescence quenching studies by 1,4-benzoquinone [BQ]
The fluorescence quenching of studied Pcs (2 and 3) were carried out by the addition of
different concentrations of BQ to a fixed concentration of the complex, and the concentrations of
BQ in the resulting mixtures were 0, 0.01, 0.02, 0.03, 0.04 and 0.0 5 mol. dm-3, respectively. The
fluorescence spectra of Pcs (2 and 3) at each BQ concentration were recorded, and the changes in
fluorescence intensity related to BQ concentration by the Stern–Volmer (SV) equation [47],
ꢀ
ꢁ
= 1 + ꢂꢃꢄ[ꢅꢆ]
(3)
ꢀ
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where I0 and I denotes the fluorescence intensity before and after the quencher addition. [BQ] is
the concentration of the quencher and KSV is the Sterne-Volmer constant which is the product of
the bimolecular quenching constant (kq) and the τF and is expressed in Eq. (4):
ꢂꢃꢄ = ꢇꢈ × ꢉꢊ
The ratios of I0/I were calculated and plotted against [BQ] according to Eq. (4), and KSV is
determined from the slope.
(4)
The fluorescence quenching of studied Pcs (2 and 3) by benzoquinone (BQ) in THF was
found to obey Stern-Volmer kinetics, which is consistent with diffusion-controlled bimolecular
reactions [44]. Fig. 8 and Fig. 9 show fluorescence emission spectral changes of 2 and 3 on
addition of different concentrations of BQ in THF. It can be seen that the fluorescence intensity
of 2 and 3 decreased strongly and no change in the λmax of studied Pcs (2 and 3). The Stern-
Volmer plots for 2 and 3 gave straight lines; depicting diffusion controlled quenching
mechanisms (insert figures of Fig. 8 and Fig. 9). KSV values and the bimolecular quenching
constant (kq) values for the BQ quenching of 2 and 3 in THF are listed in Table 2. The KSV values
of 2 and 3 are lower than unsubstituted ZnPc in THF. The bimolecular quenching constant (kq)
values of 2 and 3 are higher than for unsubstituted ZnPc in THF, thus substitution with the α-
naphtholbenzein group seems to increase the kq values of the phthalocyanine complexes.
4. Conclusion
In this study, new soluble Pcs (2 and 3) were successfully prepared from 4-
nitrophthalonitrile and α-naphtholbenzein. The new compounds were characterized by using
elemental analyses, 1H NMR, 13C NMR, UV-vis and FT-IR spectroscopy and mass spectrometry.
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The results confirmed their proposed structures. The complexes (2 and 3) have good solubility in
various organic solvents (THF, DCM, DMF and DMSO etc.) and not aggregated in THF within a
wide concentration range (1x10-5 mol dm-3 to 5x10-6 mol dm-3). Results of the aggregation studies
for 2 and 3 showed that monomeric species. The electronic spectra of compounds 2 and 3 in
different organic solvents were also analysed. The red shifts were found dependent on refractive
index of the solvents. The photophysics of phthalocyanines (2 and 3) have been extensively
investigated and compared with each other. The compound 3 shows higher fluorescence quantum
yields and shorter lifetimes when compared to unsubstituted ZnPc and it was concluded that after
additional α-naphtholbenzein substituents on 3 resulted in a decrease in fluorescence quenching.
The ΦF values of 3 are higher than for 2. The fluorescence of 2 and 3 is effectively quenched by
1,4-benzoquinone in THF.
5. Acknowledgments
This work was supported by the Research Fund of the Istanbul Technical University.
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Table Captions
Table 1.
Table 2.
Absorption, excitation and emission spectral data for 2 and 3 in THF.
Photophysical and photochemical parameters along with fluorescence
quenching data of 2 and 3 in THF.

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Table 1. Absorption, excitation and emission spectral data for 2 and 3 in THF.
Comp.
Q
Band
(log ε)
Excitation
Emission
Stoke shift
λmax, (nm)
λEx, (nm)
λEm,(nm)
∆
,
Stokes
(x105 cm-1)
668
700
4.95
4.98
670
701
2
3
708
12.5
677
5.08
678
688
9.1
ZnPc 666a
5.19a
666a
673a
14.3a
a
Ref. [36].

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Table 2. Photophysical and photochemical parameters along with fluorescence quenching
data of 2 and 3 in THF.
Comp.
ΦF
τF (ns)
τo (ns)
kF (s-1)(x107)a
KSV
kq/ (x1010 s-1)
0.19
0.27
0.25b
0.11
1.28
2.72b
0.58
3.77
10.9b
17.27
2.11
23.52
28.88
48.48b
21.38
2.26
2
3
0.92b
1.78b
ZnPc
a kF is the rate constant for fluorescence. Values calculated using kF = ΦF/τF.
b Ref. [36].

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Figure and Scheme Captions
Figure 1.
UV-vis absorption spectra of α-Naphtholbenzein, 2 and 3 in THF.
Aggregation behavior of 2 in THF at different concentrations: 5x10-6 (A),
1x10-5 (B), 2x10-5 (C), 3x10-5 (D), 4x10-5 (E) mol dm-3.
Figure 2.
Figure 3.
Aggregation behavior of 3 in THF at different concentrations: 5x10-6 (A),
1x10-5 (B), 2x10-5 (C), 3x10-5 (D), 4x10-5 (E), 5x10-5 (F) mol dm-3.
UV-vis absorption spectra of 2 in different solvents.
Figure 4.
Figure 5.
Figure 6.
UV-vis absorption spectra of 3 in different solvents.
Plots of the Q band frequencies of 2 and 3 against (n2-1)/(2n2+1), where n is
the refractive indices of the solvents.
Figure 7.
Figure 8.
Excitation and emission spectra for compound 2 and 3 in THF. Excitation
wavelength = 645 nm for 2 and 615 nm for 3 in THF.
Fluorescence emission spectral changes of 2 (10-6 M) on addition of different
concentrations of benzoquinone (BQ) in THF (insert figure, Stern–Volmer
plots for BQ quenching of 2).
Figure 9.
Fluorescence emission spectral changes of 3 (10-6 M) on addition of different
concentrations of benzoquinone (BQ) in THF (insert figure, Stern–Volmer
plots for BQ quenching of 3).
Scheme 1.
Synthetic route of the phthalonitrile derivative (1) and phthalocyanine
complexes (2 and 3); (i) DMF and K2CO3; (ii) DBU and DMF for 2; (iii)
Zn(CH3COO)2 and DMF for 3.

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Figure 1.
UV-vis absorption spectra of α-Naphtholbenzein, 2 and 3 in THF.

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Figure 2.
Aggregation behavior of 2 in THF at different concentrations: 5x10-6 (A),
1x10-5 (B), 2x10-5 (C), 3x10-5 (D), 4x10-5 (E) mol dm-3.

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Figure 3.
Aggregation behavior of 3 in THF at different concentrations: 5x10-6 (A),
1x10-5 (B), 2x10-5 (C), 3x10-5 (D), 4x10-5 (E), 5x10-5 (F) mol dm-3.

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Figure 4.
UV-vis absorption spectra of 2 in different solvents.

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Figure 5.
UV-vis absorption spectra of 3 in different solvents.

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Figure 6.
Plots of the Q band frequencies of 2 and 3 against (n2-1)/(2n2+1), where n is
the refractive indices of the solvents.

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Figure 7. Excitation and emission spectra for compound 2 and 3 in THF. Excitation
wavelength = 645 nm for 2 and 615 nm for 3 in THF.