Novel metal(III) and metal free soft phthalocyanine metal ion sensors bearing (1-hydroxyhexan-3-ylthio)-substituents: Synthesis, characterization, aggregation behavior

Article abstract of DOI:10.1016/j.poly.2014.10.014

A new substituted phthalonitrile derivative, 4-(1-hydroxyhexan-3-ylthio) phthalonitrile, was prepared by the nucleophilic displacement reaction between 1-hydroxyhexan-3-ylthio and 4-nitrophthalonitrile. The highly soluble novel metallo phthalocyanines [M: 2H (2), Ga(III) (3), In(III) (4)] with four peripheral 1-hydroxyhexan-3-ylthio groups were synthesized by cyclotetramerization. Purification of these compounds was tedious because of their high solubility and they were purified by column chromatography. They were characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MALDI-TOF and UV-Vis spectral data. The complexes were soluble in both polar solvents and non-polar solvents, such as MeOH, EtOH, CHCl₃, CH₂Cl₂, benzene, toluene and even hexane. Absorption spectral changes of the functional MPcs during addition of Ag(l) and Pd(ll) soft-metal ions were evaluated by UV-Vis spectroscopy, with monomer-dimer formation.

Full text of DOI:10.1016/j.poly.2014.10.014

Polyhedron 85 (2015) 857–863
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Novel metal(III) and metal free soft phthalocyanine metal ion sensors
bearing (1-hydroxyhexan-3-ylthio)-substituents: Synthesis,
characterization, aggregation behavior
⇑
Nevzat Akkaya, Ahmet T. Bilgiçli, Ahmet Aytekin, M. Nilüfer Yarasir, Mehmet Kandaz
Department of Chemistry, Sakarya University, TR54187 Serdivan, Sakarya, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
A new substituted phthalonitrile derivative, 4-(1-hydroxyhexan-3-ylthio) phthalonitrile, was prepared
by the nucleophilic displacement reaction between 1-hydroxyhexan-3-ylthio and 4-nitrophthalonitrile.
The highly soluble novel metallo phthalocyanines [M: 2H (2), Ga(III) (3), In(III) (4)] with four peripheral
1-hydroxyhexan-3-ylthio groups were synthesized by cyclotetramerization. Purification of these com-
pounds was tedious because of their high solubility and they were purified by column chromatography.
They were characterized by elemental analysis, FTIR, 1H and 13C NMR, MALDI-TOF and UV–Vis spectral
data. The complexes were soluble in both polar solvents and non-polar solvents, such as MeOH, EtOH,
CHCl3, CH2Cl2, benzene, toluene and even hexane. Absorption spectral changes of the functional MPcs
during addition of Ag(l) and Pd(ll) soft-metal ions were evaluated by UV–Vis spectroscopy, with mono-
mer-dimer formation.
Received 23 July 2014
Accepted 7 October 2014
Available online 24 October 2014
Keywords:
Phthalocyanine
Gallium
Indium
Metal sensor
Aggregation
Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction
phthalocyanines with enhanced optical, electronic, redox and mag-
netic properties are expected to increase their possible application
Metallophthalocyanines (MPcs), a family of aromatic macrocy-
cles based on an extensive delocalized 18- electron system, are
fields [18]. Tetra-substituted phthalocyanines are usually more
soluble than the corresponding octa-substituted phthalocyanines
due to the formation of constitutional isomers and the high dipole
moment that results from the unsymmetrical arrangement of the
substituents at the periphery [19].
p
known not only as classical dyes in practical use, but also as mod-
ern functional materials in scientific research [1]. Phthalocyanines
(Pcs) have many considerable physical and chemical features.
Therefore, they have attracted many investigators in the science
world for decades [2]. Because of these properties, phthalocyanines
have been utilized in many fields, such as gas sensors, [3] semicon-
ductor materials [4], photovoltaic cells [5], liquid crystals [6,7],
optical limiting devices [8–10], molecular electronics [11], non-
linear optical applications [12], Langmuir–Blodgett films [13],
fibrous assemblies [14] and photodynamic therapy [15].
The main disadvantage of phthalocyanines is their insolubility
in organic solvents. The lower solubility of phthalocyanines hin-
ders their utilization in many fields. However, the solubility of
Pcs is very important for investigating their chemical and physical
characteristics [16]. In order to improve the solubility of phthalo-
cyanines, several substituents, such as long alkyl, alkoxy, phenoxy
groups and crown ethers, can be added to peripheral or
non-peripheral positions of the phthalocyanines [17]. Soluble
Aggregation of phthalocyanine compounds is an important phe-
nomenon. Substituted metallophthalocyanines can form two types
of aggregations which affect their electronic and optical properties,
namely face-to-face H-aggregation and side-to-side J-aggregation
[20]. Typically, phthalocyanine aggregation results in a decrease
in intensity of the Q-band corresponding to the monomeric spe-
cies, meanwhile a new, broader and blue-shifted band is seen to
increase in intensity. This shift to lower wavelengths indicates
H-type aggregation among the phthalocyanine molecules. In rare
cases, red-shifted bands have been observed, corresponding to
J-type aggregation of the phthalocyanine molecules. Generally,
J-aggregates of Pcs occur by utilizing coordination of the side
substituent from one Pc molecule to the central metal ion in a
neighboring molecule [21]. Aggregation is usually depicted as a
coplanar association of rings, progressing from monomer to dimer
and higher order complexes. It depends on the concentration, nat-
ure of the solvent, nature of the substituents, central metal ions
and temperature [22].
⇑
Corresponding author. Tel.: +90 (264) 295 60 42; fax: +90 (264) 295 59 50.
E-mail address: mkandaz@sakarya.edu.tr (M. Kandaz).
http://dx.doi.org/10.1016/j.poly.2014.10.014
0277-5387/Ó 2014 Elsevier Ltd. All rights reserved.

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N. Akkaya et al. / Polyhedron 85 (2015) 857–863
Ga(III) and In(III) metals have been chosen as central atoms due
(KBr) m
, cmÀ1: 3365, 3230 (Ar–OH), 3089, 3020 (Ar–H), 2933,
to their heavy diamagnetic nature and axial substitution capacity.
It is known that axial substitution can introduce a dipole moment
perpendicular to the macrocycle and via a steric effect it can alter
the spatial relationship between neighboring molecules [9].
It is known that the effect of S-donor substitution on the periph-
ery for all phthalocyanines/porphyrazines results in a shift of these
intense Q bands to longer wavelenghts as a result of the electron-
donating thioether substituents when compared with those of
unsubstituted and alkyl or O-substituted derivatives [23].
In the present article, the ligand 4-(1-hydroxyhexan-3-ylthio)-
phthalonitrile was prepared according to the procedure reported
in the literatüre [24], and its tetra-substituted metal free and met-
allophthalocyanines (M = 2H, Ga(III) and In(III)) are described, Also
their soft metal ion (Ag(I) and (Pd(II)) binding properties were
investigated and evaluated.
2873 (Aliph-H), 1639, 1595, 1442, 1390, 1321, 1209, 1145, 1097,
1037, 920, 808, 740. 1H NMR (DMSO-d6) d, ppm: 8.10–7.76 (m,
12H, br, phenyl H3, H5, H6), 5.20 (s, t, br, –CH2–OH, D2O exchange-
able), 4.16 (t, br, 8H, –CH2OH), 3.40 (m, br, 4H, CH2CH(–S–)CH2),
3.33 (DMSO), 1.80-1.70 (m, 8H, CH2CH2CH), 1.47-1.32 (m, 8H, CH2-
CH2CH3), 0.98 (t, 12H, CH3).13C NMR (300 MHz, DMSO-d6) d, ppm:
149.35 (S–Ar–C4), 133.11 (Ar–C6), 132.25 (Ar–C5), 131.03 (Ar–C3),
116.85 (Ar–C3), 116.03 (Ar–C2), 115.16 (Ar–CN), 114.56 (Ar–CN),
110.25 (Ar–C1), 58.46 (–CH2OH), 40.26 (DMSO), 39.87 (S–CH–),
38.11 (CH2CH2OH), 36.12 (SCH2CH2CH3), 20.56 (CH2CH3), 14.23
(CH3). UV–Vis (THF): kmax, nm: 713 (Qx), 680 (Qy), 623 (nÀp⁄),
345 (B) (Q). MS (MALDI-TOF-MS,
a-cyano-4-hydroxycinnamic acid
(CHCA) as matrix): 1041.5 [M+H]+.
2.2.3. [Ga] 2(3),9(10),16(17),23(24)-tetrakis(1-hydroxyhexan-3-
ylthio) phthalocyanine (3)
Compound of 1 (0.25 g, 0.96 mmol) and DBU (0.05 cm3) were
pulverized in a sealed tube and heated with efficient stirring at
160 °C for 0.5 h under an inert N2 atmosphere, then anhydrous
GaCI3 (0.04 g, 0.22 mmol) was added. After heating and stirring
for 8 h, the deep green–blue product was cooled to room temper-
ature and the solid was washed successively with hot heptane, a
mixture of isopropanol and water, and then cold acetonitrile to
remove impurities until the filtrate was clear. The green-blue prod-
uct was isolated by silica gel column chromatography with THF–
MeOH (50/1 v/v) as the eluent. Complex 3 was purified again with
a second column chromatography over sephadex (5% CH3OH/
CHCl3, eluent) and then dried in vacuum. Complex 3 is moderately
soluble in CH3CN, CHCl3, CH2Cl2, THF, i-PrOH, MeOH, EtOH, DMF,
DMSO, DMAA and pyridine. Yield 0.087 g (32.80%), mp > 200 °C.
Anal. Calc. for C56H64N8O4S4GaCI (1145.2 g/mol): C, 60.81; H,
2. Experimental
2.1. Materials and methods
Chloroform (CHCl3), tetrahydrofuran (THF), 4-nitrophthalonitri-
le, GaCI3 and lnCI3 were purchased from Merck and Alfa Aesar, and
used as received. All other reagents were obtained from Fluka,
Aldrich and Alfa Aesar Chemical Co. and used without purification.
The purity of the products was tested in each step by TLC (SiO2,
CHCl3/MeOH and THF/MeOH). FT-IR spectra were recorded on a
Perkin-Elmer FT-IR spectrophotometer, where samples were dis-
persed in KBr. Chromatography was performed with silica gel
(Merck grade 60) from Aldrich. All reactions were carried out
under a dry N2 atmosphere. Elemental analysis (C, H and N) was
performed at the instrumental analysis laboratory of Marmara Uni-
versity. Time- and applied-resolved UV–Vis array spectra were
recorded. 1H and 13C NMR spectra were recorded on a Bruker
300 spectrometer instrument. Matrix-assisted laser desorption/
ionization time-of-flight (MALDI-TOF) mass spectra (MS) were
measured using a Bruker Autoflex III mass spectrometer equipped
with a nitrogen UV-Laser operating at 337 nm. The MALDI matrix,
5.79; N, 10.14. Found: C, 59.08; H, 5.83; N, 9.60%. IR (KBr)
m,
cmÀ1: 3351 (br, OH), 3059 (Ar-H), 2956, 2872 (Aliph-H), 1726
(w, H–O. . .H, weak), 1664, 1599, 1582, 1463, 1431, 1338, 1307,
1255, 1214, 1189, 1068, 919, 870, 830, 745, 644. 1H NMR
(DMSO-d6) d, ppm: 8.12–7.74 (m, br, 12H, phenyl H3, H5, H6),
5.12 (s, t, br, 4H, –CH2–OH, D2O exchangeable), 3.82 (t, br, 8H, –
CH2OH), 3.47 (m, br, 4H, CH2CH(–S–)CH2), 3.30 (DMSO), 1.80–
1.71 (m, 8H, CH2CH2CH), 1.42–1.37 (m, 8H, CH2CH2CH3), 0.98 (t,
12H, CH3). 13C NMR (300 MHz, DMSO-d6) d, ppm: 149.15 (S–Ar–
C4), 133.51 (Ar–C6), 130.87 (Ar–C5), 131.23 (Ar–C3), 115.11
(Ar–C3), 115.07 (Ar–C2), 114.98 (Ar–CN), 114.01 (Ar–CN), 109.32
(Ar–C1), 57.31 (–CH2OH), 40.85 (DMSO), 39.98 (S–CH–), 37.56
(CH2CH2OH), 35.98 (SCH2CH2CH3), 20.25 (CH2CH3), 14.01 (CH3).
UV–Vis (THF) kmax, nm: 707 (Q), 636 (n–p⁄, sh), 341 (B). MS
a-cyano-4-hydroxy-cinnamic acid (CHCA) was chosen as the best
one.
2.2. Synthesis
2.2.1. 4-(1-Hydroxyhexan-3-ylthio)phthalonitrile (1)
This compound was prepared according to the procedure
reported in the literature [24].
(MALDI-TOF-MS,
a-cyano-4-hydroxycinnamic acid (CHCA) as
matrix): 1146.5 [M+H]+.
2.2.2. 2(3),9(10),16(17),23(24)-Tetrakis(1-hydroxyhexan-3-
ylthio)phthalocyaninato metal-free) (2)
2.2.4. [In] 2(3),9(10),16(17),23(24)-tetrakis(1-hydroxyhexan-3-
Compound
1
(0.150 g, 0.405 mmol) and anhydrous 4-(1-
ylthio) phthalocyanine (4)
hydroxyhexan-3-ylthio)phthalonitrile were heated to reflux in a
sealed tube under a N2 atmosphere for 6 h. The color of the mixture
turned green-blue during the course of the reaction. Heating was
continued for an additional 2 h, then the green-blue product was
cooled to room temperature, after which the mixture was diluted
with petroleum ether. The crude product was washed several
times successively with first i-PrOH, and then cold CH3CN to
remove impurities. Finally, the product was further purified by sil-
ica gel chromatography {using THF–MeOH (50:1 v/v) and then
CHCl3/MeOH (20:1 v/v)}. The resulting oily product was washed
with copious amounts of hexane, diethyl ether and finally i-PrOH,
and then dried in vacuo. This product is soluble in MeOH, EtOH,
THF, DMF, DMSO and pyridine. Yield 0.025 g (16%), mp > 200 °C.
Anal. Calc. for C56H64N8O4S4 (1040 g/mol): C, 59.08; H, 4.66; N,
7.26; S, 16.57. Found: C, 58.75; H, 4.78; N, 7.16; S, 16.22%. FT-IR
Compound 1 (0.25 g, 0.96 mmol), anhydrous InCI3(0.03 g,
0.13 mmol) and DBU (0.05 cm3) were pulverized in a sealed tube
under a N2 atmosphere, then immediately covered. The tempera-
ture of the reaction mixture was raised to 150–160 °C and main-
tained for 8 h. After cooling to room temperature and diluting
with 2-propanol, the reaction mixture was filtered. The dark
green–blue crude product formed during the reaction was treated
with 2-propanol several times and filtered off. It was then succes-
sively washed with CH3CN and dried, followed by further purifica-
tion by column chromatography (flash column) with silica gel
(CHCl3/MeOH as the eluent, 5/100%) and dried in vacuo to give 4.
The blue phthalocyanine 4 is soluble in THF, MeOH, EtOH, DMF
and DMSO. Yield 0.07 g (27.30%), mp > 200 °C. Anal. Calc. for
C
56H64N8O4S4InCI (1190.6 g/mol): C, 61.15; H,5.82; N, 10.19.
Found: C, 60.36; H, 5.50; N, 9.62. IR (KBr)
m
, cmÀ1: 3229 (H-bonded,

N. Akkaya et al. / Polyhedron 85 (2015) 857–863
859
OH
NC
NC
NO2
HS
+
i
NC
NC
S
OH
(1)
ii
iii
HO
HO
CI
S
S
S
S
N
OH
N
OH
NH
N
N
N
N
N
N
N
M
N
N
N
HN
HO
N
HO
N
S
S
S
S
OH
M = Ga (3), In (4)
OH
M = 2H (2)
Scheme 1. Synthetic route to 2,9,16,23-tetrakis{1-hydroxyhexan-3-ylthio phtha-
locyanine M{Pc[S-CH(CH2CH2CH3)-(CH2CH2OH)]4} (M = 2H (2), Ga(III) (3), ln(III)
(4)}. (i) K2CO3, 3-mercapto-1-hexanol, DMF, 40 °C, 2 days. (ii) Without metal salt,
ca. 160–170 °C, for 6 h DBU. (iii) Anhydrous GaCI3, InCI3, 160–170 °C, for 8 h DBU.
Fig. 1. UV–Vis spectra of 2, 3 and 4 in THF.
OH), 2955 (Ar–H), 2950, 2851 (Aliph-H), 1645, 1572, 1463, 1364,
1261, 1109, 1023, 984, 801, 720, 691, 613. 1H NMR (DMSO-d6) d,
ppm: 8.10-7.75 (m, br, 12H, phenyl H3, H5, H6), 5.09 (s, t, br, 4H,
–CH2–OH, D2O exchangeable), 3.84 (t, br, 8H, –CH2OH), 3.45 (m,
br, 4H, CH2CH(–S–) CH2), 3.28 (DMSO), 1.79-1.72 (m, 8H, CH2CH2
CH), 1.58–1.46 (q, 8H, CH2CH2CH–), 1.43–1.35 (m, 8H, CH2CH2CH3),
0.96 (t, 12H, CH3).13C NMR (300 MHz, DMSO-d6) d, ppm: 149.81
(S–Ar–C4), 133.67 (Ar–C6), 130.98 (Ar–C5), 130.14 (Ar–C3),
115.19 (Ar–C3), 115.26 (Ar–C2), 114.97 (Ar–CN), 114.26 (Ar–CN),
109.66 (Ar–C1), 57.84 (ÀCH2OH), 40.84 (DMSO), 39.91 (S–CH–),
37.54 (CH2CH2OH), 36.33 (SCH2CH2CH3), 20.12 (CH2CH3), 14.86
(CH3). UV–Vis (THF) kmax, nm: 708 (Q), 631 (n–p⁄, sh), 378 (B).
Fig. 2. UV–Vis spectra of 2 in THF during titration with Ag(I) (A) and Pd(II) (B) ions
in MeOH. The variation of the absorbance at 713 and 680 nm during the titration of
2 in THF with Na2PdCl4 in MeOH (C).
MS (MALDI-TOF-MS,
a-cyano-4-hydroxycinnamic acid (CHCA) as
matrix): 1192 [M+H]+.

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N. Akkaya et al. / Polyhedron 85 (2015) 857–863
Fig. 4. UV–Vis spectra of 4 in THF during titration with Ag(I) (A) and Pd(II) (B) ions
in MeOH. The variation of the absorbance at 708 and 668 nm during the titration of
4 in THF with Na2PdCl4 in MeOH (C).
Fig. 3. UV–Vis spectra of 3 in THF during titration with Ag(I) (A) and Pd(II) (B) ions
in MeOH. The variation of the absorbance at 707 and 669 nm during the titration of
3 in THF with Na2PdCl4 in MeOH (C).

N. Akkaya et al. / Polyhedron 85 (2015) 857–863
861
Fig. 5. Absorption spectra of 2 and 3 in THF at different concentrations (inset: plot of absorbance versus concentration).
N2 atmosphere in the presence of 1,8-diazabicyclo[5.4.0] undec-
3. Results and discussion
7-ene (DBU) for 6–8 h (Scheme 1).
3.1. Synthesis and characterization
In this study, the metal ion sensor ligand 4-(1-hydroxyhexan-3-
ylthio)phthalonitrile 1, its metal free, gallium(III) and indium(III)
phthalocyanines, 2, 3 and 4, were prepared. The synthesis of the
related Pcs 2–4 was accomplished by heating a pulverized mixture
of 4-(1-hydroxyhexan-3-ylthio)phthalonitrile with anhydrous
GaCI3, InCI3 and/or without metal salt at ca. 160–170 °C under a
3.2. Spectroscopic characterization
The structure of phthalocyanines 2, 3 and 4 were verified by FT-
IR, 1H NMR and UV–Vis spectroscopic methods, as well as by ele-
mental analysis. All the analytical spectral data are consistent with
the predicted structures.

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N. Akkaya et al. / Polyhedron 85 (2015) 857–863
Fig. 6. (A) AFM images of 3, (B) AFM images of 4, (C) AFM images of 3 + Pd(II), (D) AFM images of 4 + Pd(II), prepared from THF.
Cyclotetramerization of the 4-(1-hydroxyhexan-3-ylthio)-pht-
Q band absorption was shifted to the lower energy side as a result
halonitrile to phthalocyanines 2–4 was confirmed by the disap-
pearance of the sharp –C„N vibration at 2223 cmÀ1. The IR
spectra of the phthalocyanines are very similar, with the exception
of small stretching shifts.
of the electron-donating thioether containing substituents com-
pared to that of phthalocyanines bearing oxa substituted moieties,
whereas the position of the soret-like p–
p⁄ bands of all the phthal-
ocyanines were only slightly shifted. Any increase in the concen-
tration results in a little bit of aggregation of the phthalocyanine
molecules, which is accompanied by a little blue shift of the Q-
band with a decrease in intensity.
The 1H NMR spectrum of 2 is somewhat broader than the corre-
sponding signals in the starting 4-(1-hydroxyhexan-3-ylthio)pht-
halonitrile derivative (1). This broadening is likely to be due to
chemical exchange caused by an aggregation–disaggregation equi-
libria and the fact that the product obtained in these reactions is a
mixture of positional isomers which are expected to show chemi-
cal shifts that differ slightly from each other. The isoindole protons
in 2 show a singlet in high field region at À1.35 ppm due to strong
shielding. The peripheral –OH protons at 4.50–4.70 ppm in 2–4
were easily identified in the 1H NMR spectra with a broad chemical
shift and this signal disappears on deuterium oxide, D2O, exchange
[25]. The other resonances related to OCH2, CH2, SCH2 and Ar–H
protons in the 1H NMR spectra of 2–4 are very similar to that of
the 4-(1-hydroxyhexan-3-ylthio)phthalonitrile.
3.3. Metal ion binding titration studies
It is well known that sulfur atoms on the periphery of metallo or
metal-free phthalocyanine complexes (MPcs) are optically sensi-
tive to soft metal ions, such as Ag(I) and Pd(II). Therefore, we have
employed UV–Vis spectroscopy to monitor the metal ion binding
capability of the MPcs. Each titration experiment was carried out
using a MeOH/THF solution of the MPcs (10/90, v/v) to ensure com-
plete dissolution of the analyte salt in MeOH. The concentration of
the metal salt (ca. 10À3 mol cmÀ3) was kept higher than those of
the MPc (ca. 10À5 mol cmÀ3) to diminish the absorption decreases
of the bands due to dilution. Gradual addition of Ag(I) to the solu-
tions of 2–4 at room temperature caused a gradual color change,
from green to blue, which suggests that the complexes coordinate
with Ag(I) to form aggregated species. Interaction of Ag(I) with
these complexes decreases the solubility of the dimer, trimer, tet-
ramer.. complexes formed, which results in the observation of a
small amount of an intractable product at the end of the titration
due to polymerisation. As shown in Fig. 2A (2), 3A (3) and (4),
the Ag(I) binding to the donor atoms of the complexes results in
pronounced effects on the Q-, B- and shoulder band absorptions
(n–p⁄ transitions: attributed to the non-bonding sulfur electron
The UV/Vis spectra of the phthalocyanine complexes 2–4 exhib-
ited characteristic absorptions in the Q-band region at around
650–700 nm, attributed to the
p–
p⁄ transition from the HOMO
(highest occupied molecular orbital) to the LUMO (lowest unoccu-
pied molecular orbital) of the Pc2À ring, and in the B band region
(UV region) at around 300–400 nm, arising from deeper
sitions. The Q-band absorptions of the
p⁄ transitions for all the
p–
p⁄ tran-
p
–
phthalocyanines in THF were observed as a single band of high
intensity at 713(Qx), 680 (Qy) for 2, 707 nm for 3 and 708 nm for
4. There was also a shoulder at the slightly higher energy side of
the Q band for each phthalocyanine (Fig. 1.). In the phthalocya-
nines bearing sulfanyl substituted moieties on the periphery, the

N. Akkaya et al. / Polyhedron 85 (2015) 857–863
863
(n) to the p⁄phthalocyanine orbital) [14]. The intensity of the Q and
4. Conclusion
B-bands diminished during the titration with 3 and 4 without
shifting. This means that although there was a decrease in absor-
bance (sensing to Ag(I)), formation of aggregations, both H- and
J-, were not observed
We have presented the synthesis and characterization of new
metallophthalocyanine soft metal ion sensors (2–4) containing 1-
hydroxyhexan-3-ylthio substituted groups. The structures of the
new compounds were characterized by elemental analysis, FTIR,
1H and 13C NMR, MALDI-TOF, UV–Vis spectral data and AFM
images. Their soft metal ion [Ag(I) and (Pd(II)] binding properties
and binding ratios were investigated and evaluated by UV–Vis
spectroscopy.
The gradual addition of Na2PdCl4 in MeOH (in ll portions) to 2,
3 and 4 in THF at room temperature caused a similar gradual color
change {Fig. 2B (2), 3B (3) and 4B (4)}, suggesting H-type complex
formation in the case compounds 2–4. These distinctive changes
could be attributed to the increase in the intensity of the dimeric
H-type aggregates and a decrease in the intensity of the monomers
in 2–4. During the titration, the intensity of the B-bands in 2–4
between 320 and 360 nm decreased and somewhat shifted to
longer wavelengths (the CT region).
Acknowledgements
_
We thank the Research Fund of Sakarya University and TUBITAK
Figs. 2–4C show the spectroscopic changes of the monomer/
aggregation bands of 2, 3 and 4 during titration with Pd(II) ions
(Project no: BAP-2013-02-04-049, Project no: TBAG-108T094).
{
e
versus the molar amounts of Pd(II)} and the inset plots show
the variations in the absolute values with the extinction coeffi-
cients ( ) at monomer and dimer wavelengths in response to Pd(II)
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