Novel copper(II) complexes of two tridentate ONN type ligands: Synthesis, characterization, electrical conductivity and luminescence properties

Article abstract of DOI:10.1016/j.ica.2018.02.026

Herein, we describe the synthesis and characterization of two novel tridentate ONN donor ligands, namely, (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL¹) and (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL

Full text of DOI:10.1016/j.ica.2018.02.026

Accepted Manuscript
Research paper
Novel copper(II) complexes of two tridentate ONN type ligands: Synthesis,
characterization, electrical conductivity and luminescence properties
İlyas Gönül, A.Y. Burak, Serkan Karaca, Onur Şahin, Selahattin Serin
PII:
S0020-1693(17)31327-0
https://doi.org/10.1016/j.ica.2018.02.026
ICA 18136
DOI:
Reference:
To appear in:
Inorganica Chimica Acta
Received Date:
Revised Date:
Accepted Date:
22 August 2017
8 January 2018
20 February 2018
Please cite this article as: I. Gönül, A.Y. Burak, S. Karaca, O. Şahin, S. Serin, Novel copper(II) complexes of two
tridentate ONN type ligands: Synthesis, characterization, electrical conductivity and luminescence properties,
Inorganica Chimica Acta (2018), doi: https://doi.org/10.1016/j.ica.2018.02.026
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Novel copper(II) complexes of two tridentate ONN type ligands: Synthesis,
characterization, electrical conductivity and luminescence properties
a,*
a
a
b
a
İlyas Gönül , Burak AY , Serkan KARACA , Onur ŞAHİN , Selahattin SERİN
a
Çukurova University, Department of Chemistry, Arts and Science Faculty, 01330, Adana, Turkey
b
Sinop University, Scientific and Technological Research Application and Research Center,
5
7000 Sinop, Turkey
Phone: +90 322 338 60 81/20, Fax: +90 322 338 60 70
ilyasgonul01@gmail.com
Abstract
Herein, we describe the synthesis and characterization of two novel tridentate ONN donor
1
ligands, namely, (E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL ) and
2
(
E)-2-(((2-(dimethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL ), and their copper(II)
1
2
complexes, [Cu
2
(L )
2
(CH
3
COO)
2
] (1), [Cu(L )(CH
3
COO)].2H
2
O (2). They have been
1
synthesized under conventional methods and characterized by elemental analysis, FT-IR, H-
1
3
NMR, C-NMR, ICP-OES, TGA, DSC and GC/MS analysis. For the morphological analysis
field emission scanning electron microscopy (FESEM) was used. The geometry of the Cu(II)
complexes was determined by single crystal X-ray diffraction analysis. The Cu(II) ions are in
distorted square-pyramidal coordination environments. 1 crystallizes in orthorhombic space
group, Pbca, while 2 crystallizes in monoclinic space group, P2 /c. Effects of different
1
solvents and concentrations on the photoluminescence properties of the 1-2 were investigated.
The emission bands bathochromically shifted due to increase of the dipole moments of EtOH
to H
2
O and CHCl to DMSO, respectively. As a result of the dynamic quenching, the intensity
3
of 1 was decreased with increasing the concentration in the water. The electrical conductivity
complexes 1-2 have been also investigated.
Keywords: Soluble Schiff base metal complexes, Copper (II) complexes, Luminescence,
Electrical conductivity, Single crystal X-ray
1
. Introduction
Imine groups (-C=N-) are formed by condensation of primary amines with aldehydes and
known as Schiff Bases [1]. They are one of the most widely used ligands due to the their
facile synthesis. These ligands coordinate metal atom via the imine nitrogen and other groups
1

such as carbonyl oxygen, hydroxyl or amine. The most common ones are polyfunctional
ligands and they have chelating properties. Asymmetric and symmetric Schiff base ligands
can provide suitable donor sets to acceptor metal ions. Especially, asymmetric ligands can be
used to obtain linear complexes with some control over the position of the metals [2, 3]. The
versatility of these ligands that can be coordinated to all type of metals (Lanthanides or row
transition metals) makes them very widely used to obtain coordination complexes. Metal
complexes of unsymmetrical Schiff base ligands have been rigorously studied and used in
different fields including magnetic materials [4, 5], catalysis [6], chemical analysis,
bioinorganic and medical chemistry [7-10].
In this study, we report the synthesis and characterization of new unsymmetrical
tridentate ONN Schiff base ligands and their copper (II) complexes (1-2). The ligands
obtained from N',N'-dimethylethane-1,2-diamine and 2-hydroxy-3-methoxy benzaldeyhde
1
2
(
HL ), N',N'-dimethylethane-1,2-diamine and 3-ethoxy-2-hydroxy benzaldeyhde (HL )
(
Scheme 1). The synthesized compounds fully characterized by elemental analysis, thermal
1
13
analysis, FT-IR, H-NMR, C-NMR, mass spectra, ICP-OES and single crystal X-ray
analysis. Solubility test were performed for the 1 and 2. The test showed that synthesized
metal complexes are extremely soluble in all common organic and inorganic solvents except
hexane (Table S1). Due to the this feature, luminescence properties of the compounds were
-4
-7
investigated in different concentrations (1.0 x 10 to 1.0 x 10 M) and solvents. The electrical
conductivity properties of the complexes have been also investigated.
2
. Experimental
2
.1. Materials and methods
All chemicals and solvents were purchased from commercial sources and used without further
purification. Perkin-Elmer RX-1 FT-IR with KBr pellets spectrometer in the range of 4000-
-1
4
00 cm was used for the IR analysis of the compounds. Thermo Flash 2000 CHNS analyzer
TM
was used for the elemental analysis. Avance III HD Ascend
600 MHz ULH High
1
13
Resolution Fluid NMR Spectrometer was used for the H-NMR and C-NMR analyses of the
ligands. The melting points of the metal complexes were determined using a Gallenkamp
MPD 350 BM 2.5 capillary melting point apparatus. Quantitative metal analyses were
performed with Perkin-Elmer Optima 2100DV ICP-OES instrument. Perkin Elmer Pyris
Diamond TG/DTA equipment was used for the TG analyses. Differential scanning
2

calorimeter (DSC) studies were made on Perkin Elmer DSC 4000. Mass spectrometry (MS)
analysis of the ligands was measured by Thermo Scientific ISQ Single Quadrupole GC-MS
with TR5MS capillary columns. The FESEM images of the compounds were recorded using
Carl Zeiss, SUPRA-55. The electrical conductivity properties of compounds were determined
by four-point probe method with an Electrometer Entek Electronic FPP-470. Solid pellets
were prepared by Graseby SPECAC Laboratory Manual Hydraulic press under 15 tons
pressure. Perkin-Elmer LS 55 Luminescence Spectrometer was used for the solid and liquid
state phosphorescence excitation and emission spectra. LEICA EZ4W stereo microscope was
used for the high definition views of the complexes.
1
2
.2. Synthesis of HL
N',N'-dimethylethane-1,2-diamine (0.088 g, 1.0 mmol) and 2-hydroxy-3-methoxy
benzaldeyhde (0.152 g, 1.0 mmol) were dissolved by heating in 40 mL and 20 mL of MeOH
separately. Then, aldehyde solution was added dropwise to the hot amine solution and the
mixture was boiled under reflux for 3 hours. The resulting viscous yellow liquid was cooled
to room temperature. The obtained organic ligand dried over anhydrous Na
2
SO and
4
1
concentrated in vacuo. The yellow liquid ligand HL (Scheme 1-i) was obtained in high yield
-1
(
98.85%, based on GC-MS analysis). FT-IR data (cm ): 3425(m), 2942(m), 2827(m),
1
2
773(m), 1632(s), 1466(s), 1255(s), 1081(m), 966(m), 840(w), 781(w), 737(m). H NMR
(
DMSO, ppm, 600 MHz) δ: 8.51 (s, 1H, CH=N), 6.74-7.00 (m, 3H), 13.84 (s, 1H, C–OH),
1
3
2
.18 (s, 3H, N–CH
3
), 3.77, (s, 3H, O–CH
3
). C NMR (DMSO, ppm, 600 MHz) δ: 153.3 (C–
OH), 166.7 (CH=N), 45.7 (CH
3
–N), 56.5 (O–CH
3
), 115.0-148.8 (Aromatic Carbons). The
1
+
detailed NMR spectra of the HL are shown in Figs. S1-S7. MS (70eV): m/z 222 [M ], 179
2
2
+
+
2+
+
[
C
10
H13NO
], 136 [C
8
H
9
O
2
], 73 [H
2
C-CH
2
-NH-CH
3
-CH
3
] , 58.04 [CH
2
=N-CH
3
-CH ] .
3
2
2
.3. Synthesis of HL
N',N'-dimethylethane-1,2-diamine (0.088 g, 1.0 mmol) and 3-ethoxy-2-hydroxy benzaldeyhde
0.166 g, 1.0 mmol) were dissolved by heating in 40 mL and 20 mL of MeOH separately.
(
Then, aldehyde solution was added dropwise to the hot amine solution and the mixture was
boiled under reflux for 3 hours. The resulting viscous light brown liquid was cooled to room
temperature. The obtained organic ligand dried over anhydrous Na
2
SO and concentrated in
4
2
vacuo. The liquid ligand HL (Scheme 1-ii) was obtained in high yield (97.43%, based on
-1
GC-MS analysis). FT-IR data (cm ): 3440(m), 2977(m), 2935(w), 2817(s), 2784(s), 1633(s),
3

1
1
8
4
466(s), 1251(s), 1078(m), 897(w), 781(w), 738(m). H NMR (DMSO, ppm, 600 MHz) δ:
.50 (s, 1H, CH=N), 13.85 (s, 1H, C–OH), 6.73-6.99 (m, 3H), 2.18 (s, 3H, N–CH ), 3.98-
). C NMR (DMSO, ppm, 600 MHz) δ: 153.4 (C–OH), 166.8
3
13
.10, (q, 2H, O–CH
2
–CH
3
(
CH=N), 45.7 (CH
3
–N), 15.3 (O–CH
2
CH
3
), 116.5-147.8 (Aromatic Carbons). The detailed
2
+
NMR spectra of the HL are shown in Figs. S8-S14. MS (70eV): m/z 236 [M ], 193
2
2
+
+
+
+
[
C
11
H15NO
], 123 [C
7
H
7
O
2
], 72 [C
4
H
10N ], 58.01 [CH
2
=N-CH
3
-CH ] .
3
Scheme 1. Synthesis of tridentate ONN donor ligands.
1
2
.4. Synthesis of [Cu
2
(L )
2
(CH
3
COO) ] (1)
2
1
The synthesized HL ligand (0.445 g, 2.0 mmol) was dissolved in hot MeOH (30 mL). A
MeOH solution (20 mL) of anhydrous copper(II) acetate (0.363 g, 2.0 mmol) was added to
the reaction medium and the mixture was boiled under reflux for 3 hours. After on cooling to
room temperature, the solution was left to crystallize for one month. Obtained green single
crystals suitable for X-ray diffraction (Scheme 2a). Anal. Calcd. for C28
H
40
N
4
O
8
Cu : C,
2
4
8.90; H, 5.86; N, 8.15. Found: C, 48.48; H, 5.80; N, 7.76%. The ICP-OES analysis (%)
-1
showed that 1 contained Cu: 17.10; Calcd.: Cu: 18.48. FT-IR data (cm ): 3345(m), 3040(m),
2
1
983(m), 2927(s), 2828(s), 1624(s), 1604(s), 1470(s), 1447(s), 1376(s), 1327(s), 1220(s),
068(w), 850(w), 780(w), 732(s), 676(w), 576(w), 460(w), 431(w).
4

2
2
.5. Synthesis of [Cu(L )(CH
3
COO)].2H O (2)
2
2
The synthesized HL ligand (0.236 g, 1.0 mmol) was dissolved in hot MeOH (30 mL). A
MeOH solution (20 mL) of anhydrous copper(II) acetate (0.182 g, 1.0 mmol) was added to
the reaction medium and the mixture was boiled under reflux for 3 hours. After on cooling to
room temperature, the solution was left to crystallize for one month. Obtained green single
crystals suitable for X-ray diffraction (Scheme 2b). Anal. Calcd. for C16
H
30
N
2
6
O Cu: C, 46.88;
H, 7.38; N, 6.83. Found: C, 47.53; H, 7.21; N, 6.13%. The ICP-OES analysis (%) showed that
-1
2
2
1
contained Cu: 14.83; Calcd.: Cu: 15.50. FT-IR data (cm ): 3552(m), 3465(m), 3394(m),
983(m), 2920(m), 2873(m), 1635(s), 1586(m), 1468(s), 1442(s), 1384(s), 1238(m), 1217(s),
074(m), 1019(m), 907(s), 785(m), 725(s), 679(s), 534(m), 463(m).
Scheme 2. High definition microscope views of the 1 (a) and 2 (b).
2
.6. X-ray diffraction analysis
Suitable crystals of 1-2 were selected for data collection which was performed on a D8-
QUEST diffractometer equipped with a graphite-monochromatic Mo-K radiation at 296 K.
α
The structures were solved by direct methods using SHELXS-97 [11] and refined by full-
5

2
matrix least-squares methods on F using SHELXL-2013 [12]. All non-hydrogen atoms were
refined with anisotropic parameters. The H atoms of C atoms were located from different
maps and then treated as riding atoms with C-H distances of 0.93-0.97 Å. The water H atoms
were located in a difference map refined subject to a DFIX restraint. The following
procedures were implemented in our analysis: data collection: Bruker APEX2 [13];
absorption effects using the multi-scan method (SADABS) [13a]; the frames were integrated
with the Bruker SAINT software package [13b] using a narrow-frame algorithm; program
used for molecular graphics were as follow: MERCURY programs [14]; software used to
prepare material for publication: WinGX [15]. Details of data collection and crystal structure
determinations are given in Table 1. The selected bond lengths and bond angles are given in
Table 2.
3
. Results and discussion
3
.1. Descriptions of crystal structures
The molecular structure of 1, with the atom numbering scheme, is shown in Fig. 1. The
asymmetric unit of the complex 1 consists of one Cu(II) ion, one acetate molecule and one
1
HL ligand. The Cu(II) ion is coordinated by two nitrogen and one oxygen atoms (N1, N2 and
1
i
O2) from HL ligand and two bridging oxygen atoms (O3 and O3 ) from acetate molecules
(i) -x+1, -y+1, -z+1]. The Cu(II) ion is in a distorted square-pyramidal coordination
[
environment. The two bridging oxygen atoms are quite different, the equatorial oxygen atom
exhibits a Cu1-O3 distance of 1.967(2) Å, while that of the axial oxygen atom is much longer
with 2.409(2) Å. In addition, the Cu∙∙∙Cu separation is about 3.455 Å. A dimer of two
monomeric units bridged by two acetate ions reveals an inversion centre in the middle of the
molecules.
6

Figure 1. The molecular structure of 1 showing the atom numbering scheme.
The bond distances of Cu1-N1 and Cu1-N2 are 1.963(3) and 2.092(3) Å and the other Cu1-
O2 bond length is 1.927(3) Å, respectively. Molecules of 1 are linked into sheets by a
combination of C-H∙∙∙O hydrogen bonds (Table 3). The combination of C-H∙∙∙O hydrogen
bonds produce C(7) chain running which is parallel to the [110] direction (Fig. 2). The
2
asymmetric unit of 2 consists of one Cu(II) ion, one HL ligand, one acetate molecule and
two non-coordinated water molecules (Fig. 3).
Figure 2. An infinite 1D layer in 1.
7

Figure 3. The molecular structure of 2 showing the atom numbering scheme. [(i) x, 1/2-y, z-1/2].
Figure 4. An infinite 1D layer in 2.
The Cu(II) ion is coordinated by two nitrogen and one oxygen atoms (N1, N2 and O1) [Cu1-
2
N1= 1.951(2) Å, Cu1-N2= 2.104(2) Å and Cu1-O1= 1.9364(16) Å] from HL ligand and two
i
i
oxygen atoms (O3 and O4 ) [Cu1-O3= 1.9856(16) Å and Cu1-O4 = 2.3293(17) Å] from
acetate molecules, thus showing a distorted square-pyramidal coordination geometry [(i) x, -
y+1/2, z-1/2]. The Cu(II) ions and acetate molecules generate 1D coordination polymer
8

running parallel to the [001] direction (Fig. 4). The Cu(II)∙∙∙Cu(II) separation is 4.929 Å.
Adjacent 1D coordination polymers are further joined by O-H∙∙∙O and C-H∙∙∙O hydrogen
bonds, generating a 2D supramolecular network (Fig. 5).
Table 1
Crystal data and structure refinement parameters for complexes 1-2.
_
____________________________________________________
Crystal data
1
2
Empirical formula
C
28
H
40
N
4
O
8
Cu
2
C
15
H
26
N
2
6
O Cu
Formula weight
Temperature
Crystal system
Space group
a (Å)
687.72
296(2) K
393.92
296(2) K
Monoclinic
P2 /c
Orthorhombic
Pbca
1
8.440 (4)
17.021 (7)
21.338 (12)
90.00
9.214 (2)
21.826 (7)
9.790 (3)
109.282 (9)
1858.4 (9)
4
b (Å)
c (Å)

(º)
3
V (Å )
3065.0 (3)
4
Z
-3
D
c
(g cm )
1.490
1.408
-1
μ (mm )
1.44
1.21
θ range (º)
3.1-27.6
25353
3.0-28.0
48674
Measured refls.
Independent refls.
3866
4799
R
int
0.088
0.060
S
1.09
1.23
R1/wR2
0.051/0.181
0.042/0.108
0.55/-0.59
-3

max/min (eÅ ) 0.56/-0.75
_
____________________________________________________
9

Figure 5. An infinite 2D layer in 2.
Table 2
Selected bond lengths [Å] and angles [°] for 1-2.
_________________________________________________________________________
_
Complex 1
N1-Cu1
N2-Cu1
O2-Cu1
O3-Cu1
O2-Cu1
C11-N2
i
1.963(3)
2.092(3)
1.927(3)
1.967(2)
2.409(2)
1.476(5)
Cu1-O3-Cu1
C11-N2-Cu1
O3 -Cu1-N1
O2-Cu1-O3
N1-Cu1-O3
N2-Cu1-O2
N1-Cu1-N2
103.82(10)
110.4(2)
i
112.65(11)
90.38(10)
171.08(12)
173.10(10)
83.19 (13)
Complex 2
Cu1-O3
Cu1-O1
Cu1-N2
Cu1-N1
1.9856(16)
1.9364 (16)
2.104(2)
1.951(2)
2.3293(17)
1.488(3)
O3-Cu1-O1
O1-Cu1-N2
N2-Cu1-N1
Cu1-O3-C14
Cu1-N2-C12
91.79(7)
173.15(7)
83.74(9)
112.38(14)
110.86(16)
89.64(8)
i
Cu1-O4
N2-C11
i
N1-Cu1-O4
C14-O4-Cu1
ii
139.88(16)
_
_________________________________________________________________________
1
0

Table 3
Hydrogen-bond parameters for 1-2 (Å, º).
D-H· · ·A
1
C8—H8···O4
C11—H11C···O1
C11—H11C···O2
C12—H12B···O4
2
C13—H13B···O4
C13—H13B···O1
C10—H10A···O6
C9—H9···O6
O5—H5B···O3
O5—H5A···O1
O5—H5A···O2
D-H
H···A
D···A
D-H···A
ii
0.93
0.96
0.96
0.96
2.30
2.60
2.45
2.58
3.196 (4)
3.228 (5)
3.348 (4)
3.266 (6)
161
124
156
128
i
i
i
i
0.96
0.96
0.97
0.93
0.82 (2)
0.81 (2)
0.81 (2)
0.82 (2)
0.81 (2)
2.56
2.56
2.49
2.54
2.26 (2)
2.44 (3)
2.08 (2)
2.09 (2)
2.04 (2)
3.196 (3)
3.422 (3)
3.400 (4)
3.405 (4)
3.035 (3)
2.933 (3)
2.862 (3)
2.902 (3)
2.849 (3)
124
149
155
155
159
120
162
170
173
iii
O6—H6B···O3
O6—H6A···O5
iv
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1/2, −y+3/2, −z+1 for 1;
i) x, −y+1/2, z−1/2; (iii) x−1, −y+1/2, z−1/2; (iv) x−1, y, z−1 for 2.
(
3
.2. GC-MS analysis
GC/MS analysis was used to characterization of the synthesized liquid ligands by using
TR5MS column. Helium was used as a carrier gas at a flow rate of 1.0 mL/min. The ion
1
2
source temperature was set to 250 °C. The 1 μl HL and HL were injected in pulsed split
mode ratio 100. Injector temperature was set at 240 °C and throughout the process
temperature flow was set at the speed of increasing 15 °C/min. The oven temperature program
was as follows: Initial temperature 80 °C held for 1 min, 15 °C/min till 280 °C held for 10
min. Mass spectra were detected on a ISQ detector (temperature trap 250 °C) in a range of
m/z 50-600. Ionization mode was internal EI (energy of electrons 70 eV); sample volume, 1
µL; solvent, DCM.
3
.3. Mass Spectral interpretation and identification of ligands
The synthesized ligands were also characterized by using GC/MS analysis. Since the ligands
were obtained as pure, single chromatograms were obtained (Figs. S15 and S17). All
1
1

1
2
fragments of HL and HL were fully characterized in Figs. S16 and S18 according to the
their mass (m) to charge (z) ratios (m/z). In this section, only the spectrums seen as important
+
are explained. The mass spectrums indicated molecular weight of 222 (m/z: 223 MH ion)
which is consistent with the molecular weight of the ligand. The m/z: 58.04 ion was observed
1
in HL as highest abundance. This peak is base peak and most stable ion in the structure (m/z:
+
+
5
8.07, [CH
2
=N-CH
3
-CH
3
] ). The line at m/z: 136 is typical of an C
8
H
9
O
2
. The m/z: 179
2
+
+
fragment ion corresponds to the loss of C10
H13NO
2
from MH . The m/z: 73 ion due to the
2
+
+
[
H
2
C-CH
2
-NH-CH
3
-CH
3
] from MH . Similarly, only the spectrums seen as important are
2
+
explained for HL . The mass spectrums indicated molecular weight of 236 (m/z: 237 MH
ion) which is consistent with the molecular weight of the ligand. The m/z: 58.01 ion was also
2
observed in HL as highest abundance. This peak is base peak and most stable ion in the
+
+
structure (m/z: 58.07, [CH
2
=N-CH
3
-CH
3
] ). The line at m/z: 123 is typical of an C
7
H
7
O .
2
2
+
+
The m/z: 193 fragment ion corresponds to the loss of C11
H15NO
2
from MH . The m/z: 72
+
+
ion due to the C H10N from MH . These mass spectra results were supported the structure of
4
the ligands and in agreement with the data from the single crystal X-ray analysis of the
complexes.
3
.4. FT-IR spectra
The infrared spectra of the synthesized ligands and their copper(II) complexes are presented
1
2
-
in Figs. S19-S22. In HL and HL ligands, phenolic OH groups appears at 3425 and 3440 cm
1
-1
-1
,
respectively. Medium intensity bands in the range of 2945-2770 cm and 2980-2780 cm
due to aliphatic C-H stretching of ligands. The azomethine bonds υ(CH=N) of the ligands
-
1
were appeared at 1632 and 1633 cm , respectively. The υ(C-OH) bands were observed at
-1
-1
1
1
466 cm for both ligands [16]. The strong bands observed at 1255 cm (For HL ) and 1251
-1
2
cm (For HL ) assigned to υ(C-O) stretching vibrations. In copper(II) complexes, aliphatic
-1
υ(C-H) stretching groups were appeared between 3000-2800 cm . The IR spectra of 2, broad
-
1
band in the range 3390-3550 cm assignable to υ(O-H) of the uncoordinated water molecules.
-1
-1
After the coordination, imine bonds were shifted at 1624 cm (for 1) and 1635 cm (for 2).
-
-
Asymmetric υas(COO ) and symmetric υ
s
(COO ) stretching bands of the acetate groups were
-1
-1
observed in the ranges 1447-1470 and 1220-1244 cm for 1, 1468-1442 and 1217-1238 cm
-1
for 2 [17]. The new bands were seen at 576-534 and 460-463 cm due to the υ(Cu-O) and
υ(Cu-N) vibrations, respectively [18, 19].
1
2

3
.5. TG and DSC Analysis
To determine the thermal behavior of the synthesized complexes, TG analysis were performed
in the temperature range from 25 to 800 °C under N atmosphere with a heating rate of 10
2
-
1
ºC.min . The synthesized ligands were as liquid phase so we could not performed TG
analysis for them. TG and TG/DTG curves of the 1 and 2 are shown in Figs. S23-S24. The
compound 1 is thermally stable up to 200 ºC. Above this temperature, the TGA curve of 1
only showed one weight loss step from 201 to 320 °C, corresponding to the completely
decomposition of the complex. In the TG curve of complex 2, two weight losses were
observed in contrast to complex 1. The first weight loss in the temperatures 25-90 ºC, which
correspond to loss of solvated methanol molecules. The last weight loss of in the temperature
range of 140-345 °C corresponds to the decomposition of organic ligands in the structure. The
remained residuals are attributed to the final product of CuO moieties. DSC analysis were
carried out between 25 and 400 °C under a nitrogen atmosphere. DSC thermograms of 1 and
2
shown in Figs. S25-S26. The DSC curve of 1 exhibited an endothermic peak at 212.5 °C
corresponding to the melting point of 1. The second curve at 256.5 °C was corresponding to
its thermal decomposition. DSC curve of the 2 exhibited three endothermic peaks. DSC
spectrum of 2 showed a small endothermic peak between 80-100 °C that may attribute to
evaporation of water content. Second endothermic peak at 176.8 °C corresponding to the
melting point of 2. The last curve at 257.5 °C was corresponding to the thermal
decomposition of compound 2.
3
.6. Morphologies of the complexes
The FESEM images provided direct information about the shape and size of the synthesized
compounds. The FESEM images of 1-2 are shown in Fig. 6. The morphologies of the
compounds were investigated by FESEM images in different magnifications. The images of
the 1 displayed a smooth and mottled image in the cluster-like crystallized specimen. The
sizes of the mottled range from 122 to 366 nm. The image of 2 is found to be more relatively
smooth and homogeneous compared to 1. The image of 2 showed much less smooth with
sharp and rough structure. Their morphologies were found in different shapes and sizes vary
from 200 nm to 20 μm for 1 and 100 nm to 10 μm for 2 due to the using different ligands.
1
3

Figure 6. FESEM images of single crystals of 1 (a-d) and 2 (e-h).
3
.7. Photoluminescence properties
Photoluminescence properties of the synthesized ligands and their copper(II) complexes were
-5
investigated in H O using 1.0 x 10 M concentration. As shown in Fig. 7, it was obtained
2
1
2
sharp and narrow emission spectra in all compounds. The free HL and HL ligands exhibited
sharp emission bands at λmax: 529 and 532 nm when excited at 330 and 325 nm, respectively.
The observed emission bands may be attributed to the ligand centered π*→π transitions in the
organic molecules. 1 and 2 showed single emission bands at λmax: 618 and 617 nm upon
excitation with wavelengths of 326 and 335 nm, respectively. The wavelength of maximum
1
2
emission peaks of 1 and 2 were red shift as 89 and 85 nm compared with that of HL and HL
ligands. It is showed that electron donating groups in the structures can lead to red-shift of the
emission spectra of the ligands and their metal complexes.
1
4

Figure 7. Emission spectra of the free ligands and their copper(II) complexes.
3
.8. The effect of different solvents on the photoluminescence properties of the 1-2
The photoluminescence properties of the copper(II) complexes were investigated in EtOH,
-
5
DMSO, CHCl
3
and H O solvents using 1.0 x 10 M concentrations at 298 K and obtained
2
data are given in Table 4. The emission spectra of the complexes gave one emission bands
with high intensities for all solvents in different wavelengths (Fig. 8). The using four different
solvents not only have different polarity (Polarity: H
2
O > EtOH > DMSO > CHCl ), but also
3
present important differences that water and ethanol are protic solvents while the dimethyl
sulfoxide and chloroform are aprotic. The emission bands were observed 446, 495, 507 and
6
17 nm for 1 and 414, 433, 445 and 616 nm for 2 in CHCl
respectively. The emission of complexes 1 and 2 were observed to shift from 446 to 617 nm
and 414 to 616 nm with increasing in the solvents polarity from CHCl to H O, corresponding
to the specific solute/solvent interactions [19a]. H O and EtOH are polar protic solvents,
which are hydrogen bond donor with strong polarity, they have very strong interaction with
solute through hydrogen bond. DMSO and CHCl are polar aprotic solvents, and these kind of
solvents cannot be used as hydrogen bond donor [20]. As a result, there has been a slight red
shift to longer wavelength in polar aprotic solvents (446 nm in CHCl to 495 nm in DMSO
for 1, 414 nm in CHCl to 495 nm in DMSO for 2). The emission bands changed really strong
and huge red shifted to 507 nm (EtOH) to 617 nm (H O) for 1, 445 nm (EtOH) to 616 nm
3
, DMSO, EtOH and H
2
O,
3
2
2
3
3
3
2
1
5

(
H
2
O) for 2 using polar protic solvents. The emission bands bathochromically shift may be
due to increase of the dipole moments of EtOH to H O and CHCl to DMSO, respectively.
2
3
(
a)
(
b)
Figure 8. Normalized emission spectra of 1 (a) and 2 (b) in H
2
O, EtOH, DMSO and CHCl solvents
3
-5
(
Concentrations: 1.0 x 10 M).
Table 4
Emission data of the 1-2 in different solvents.
______________________________________________________
Complex 1 Complex 2
_
Solvent
_________________ _________________
Wavelength (nm)
Wavelength (nm)
_
_______________
________________
________________
CHCl
DMSO
EtOH
3
446
495
507
617
414
433
445
616
2
H O
_
______________________________________________________
-5
Solvent concentrations: 1.0 x 10 M, λex : 320 nm.
1
6

3
.9. The effect of concentrations on the photoluminescence properties of the 1-2
To determine the concentration effect of the complexes in water, samples were prepared in
different molar concentrations. EtOH, DMSO and CHCl solvents gave very same emission
3
-4
-7
bands in 1.0 x 10 - 1.0 x 10 M so we investigated only in water with different
concentrations. The obtained data are given in Table 5. The photoluminescence spectra of the
1
and 2 are shown in Fig. 9. The emission spectra of the 1, maximum intensity was obtained
-7
at λem:573 nm (Int: 507) in the 1.0 x 10 M concentration when excited at 310 nm. The
-4
emission spectra of the 1 great red-shifted (λem :641 nm for 1.0 x 10 M) and their intensities
-7
-4
decreased (Int:507 to 150) from 1.0 x 10 to 1.0 x 10 M concentration. On the other hand,
-4
maximum intensity (Int:332) and emission value (λem :625 nm) were obtained in 1.0 x 10 M
for the complex 2 (λex : 315 nm). The emission spectra of the 2 great red-shifted (λ :596 nm
-7
-7
-4
for 1.0 x 10 M) and their intensities increased (Int: 95 to 332) from 1.0 x 10 to 1.0 x 10 M
concentration. It was observed that both complexes showed red shift with increasing of the
concentration. Interestingly, the intensity of 1 was decreased while the intensity of 2 was
increased with increasing the concentration of the solvents. This situation is due to the
presence of ethoxy group in complex 2. The increasing the number of electron-donating
groups has led to increase the intensity. Weak hydrogen bonds were observed between
molecules in complex 1. On the other hand, coordinated acetate bridges were linked each
other between molecules in complex 2. In complex 1, hydrogen bonds energy transfer
absorbed by each molecules cause dynamic quenching [20a]. As a result of the dynamic
quenching, the intensity of 1 was decreased with increasing the concentration in the water. It
was not observed any differences in the intensities or wavelegnths of the complexes by using
EtOH, DMSO and CHCl as solvents. When used water as a solvent, dynamic quenching was
3
observed in complex 1 due to the hydrogen bonds. Fluorescence quenching refers to any
process that decreases the fluorescence intensity of a sample. A variety of molecular
interactions can result in quenching. These include excited-state reactions, molecular
rearrangements, energy transfer, ground-state complex formation, and collisional quenching
[
20b].
1
7

(
a)
(
b)
Figure 9. The photoluminescence emission spectra of the 1-(a) and 2-(b) in different concentrations.
Table 5
Emission and intensity data of 1 and 2 in different concentrations.
_
_____________________________________________________________________
Complex 1
Complex 2
_
_________________________________ __________________________________
Concentration Wavelength Intensity Concentration Wavelength Intensity
M) (nm) (a.u.) (M) (nm) (a.u.)
(
_
_________________________________ __________________________________
-4
-4
-5
-6
-7
1
1
1
1
.0 x 10-
641
618
596
573
150
272
392
507
1.0 x 10
1.0 x 10
1.0 x 10
1.0 x 10
625
617
609
596
332
245
172
95
5
.0 x 10-
6
.0 x 10-
7
.0 x 10
_
_____________________________________________________________________
2
Solvent: H O, λex : 310 nm for 1, 315 nm for 2.
1
8

Electrical conductivity
Solid conductors have been proposed as alternative to liquid based electrolytes, where
inorganic solid conductors and solid polymer conductors are included. Among them, solid
phase materials have attracted interest in devices because of its easier processability,
mechanical properties and thermal stability [21, 22]. In line with this target, the crystal
samples (0.05 g) were weighed and pelleted under pressure (15 tons) as a solid phase. Their
thickness (0.291 mm for 1; 0.323 mm for 2) and diameters (1.0 cm) were measured. Electrical
conductivity values of the copper(II) complexes were measured by four-point probe method.
Average conductivity values were calculated by taking five parallel measurements. The
1
-3
-1
highest electrical conductivity was exhibited by [Cu
2
(L )
2
(CH
3
COO) ] with 1.2 x 10 S.cm
2
2
at 25 ºC. The sample [Cu(L )(CH
3
COO)].2H O showed the maximum conductivity of 9.1 x
2
-4
1
0 S/cm at ambient temperature. Due to the dimeric copper(II) structure of the 1 and having
methoxy groups, it was observed to show more conductivity than complex 2. The obtained
results are similar to those reported previously for conducting and semiconducting studies as
ionic conductivity and solid phase conductivity [23, 24]. As shown in Fig. 10, Kaur et al.’s
reported conductivity range of materials and their conductivity values [25]. In our study,
-4
-2
-1
obtained compounds showed conductivity values between 10 and 10 S.cm . Given the
reported ranges, the synthesized compounds can be used as semiconducting material as solid
phase.
Figure 10. Conductivity range of conducting and semiconducting materials [25].
1
9

4
. Conclusions
1
2
In summary, the asymmetric Schiff base ligand HL and HL were synthesized in
1
13
conventional method. They were characterized by FT-IR, H-NMR, C-NMR, mass spectra.
1
2
The copper(II) complexes of HL / HL were also synthesized and characterized by elemental
analysis, FT-IR, TGA, ICP-OES and single crystal X-ray diffraction analysis. The metal
complexes exhibited distorted square-pyramidal geometrical arrangements. 1 and 2 showed
-3
-4
-1
excellent electrical conductivity values of 1.2 x 10 and 9.1 x 10 S.cm at room
temperature, respectively. Luminescence properties of the complexes were also investigated
in different polar solvents such as H
concentration. It was not observed any emission differences by using C
DMSO as solvent except H O. It has been observed that there is an increase in emission
2
O, C
2
H
5
OH, CHCl
3
and DMSO with increased
2
H
5
OH, CHCl and
3
2
values with increasing concentration in water.
Acknowledgements
The authors gratefully acknowledge financial support from the Research Unit of Çukurova
University (Grant No. FBA-2017-7794), and Scientific and Technological Research
Application and Research Center, Sinop University, Turkey, for the use of the Bruker D8
QUEST diffractometer.
Appendix A. Supplementary material
Crystallographic data for the structural analysis have been deposited with the Cambridge
Crystallographic Data Centre, CCDC No. 1546599 for 1 and 1546600 for 2. Copies of this
information may be obtained free of charge from the Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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1
(
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7
567.
2
1

Figures
Figure 1
Figure 2
2
2

Figure 3
Figure 4
2
3

Figure 5
Figure 6.
2
4

Figure 7.
2
5

(
a)
(
b)
Figure 8.
2
6

(
a)
(
b)
Figure 9.
Figure 10.
2
7

Figure Captions
Figure 1. The molecular structure of 1 showing the atom numbering scheme.
Figure 2. An infinite 1D layer in 1.
Figure 3. The molecular structure of 2 showing the atom numbering scheme. [(i) x, 1/2-y, z-
1
/2].
Figure 4. An infinite 1D layer in 2.
Figure 5. An infinite 2D layer in 2.
Figure 6. FESEM images of single crystals of 1 (a-d) and 2 (e-h).
Figure 7. Emission spectra of the free ligands and their copper(II) complexes.
Figure 8. Normalized emission spectra of 1 (a) and 2 (b) in H
2
O, EtOH, DMSO and CHCl
3
-5
solvents (Concentrations: 1.0 x 10 M).
Figure 9. The photoluminescence emission spectra of the 1-(a) and 2-(b) in different
concentrations.
Figure 10. Conductivity range of conducting and semiconducting materials [25].
2
8

Highlights



Copper(II) transition metal complexes based on tridentate ONN donor ligands have
been synthesized.
Luminescence properties of the synthesized compounds were investigated both in
solution and solid state.
The synthesized 1-2 can be used as semiconducting material as solid phase.
2
9