Design, XRD/HSA-interactions, spectral, thermal, Solvatochromism and DNA-binding of two [Cu(phen)(triene)]Br2 complexes: Experimental and DFT/TD-DFT investigations

Article abstract of DOI:10.1016/j.molstruc.2021.129983

Two dicationicCu(II) complexes of [Cu(phen)(NNN)]Br₂ (1-2) general formula [phen = 1,10-phenanthroline, NNN = diethelenetriamine (dien) (1) and dipropylenetriamine (dipn)(2)], have been synthesized in very good yields. The two complexes were characterizedvia UV-vis., CHN-EA, MS, FT-IR, thermal, and X-ray crystallographic techniques. XRD data for 1 showed a distorted square pyramidal Cu(II) ions geometry center with three uncoordinated water molecules. TGA were performed to evaluate the interactions strength and found to support the XRD molecular interactions results. The time-dependent density functional theory (TD-DFT) and electron transfer processes were modeled, and consequently the absorption maxima around 610 and 280 nm were attributed to d–d and Phen(π)→Phen(π?) transitions. Positive Gutmann'ssolvatochromismbehavior of both complexes have been recorded. Furthermore, the ability of the two complexes for DNA binding was evaluatedvia absorption studies in the visible region showing high K_b constant values.

Full text of DOI:10.1016/j.molstruc.2021.129983

Journal of Molecular Structure 1231 (2021) 129983
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Design, XRD/HSA-interactions, spectral, thermal, Solvatochromism and
DNA-binding of two [Cu(phen)(triene)]Br2 complexes: Experimental
and DFT/TD-DFT investigations
Muheeb Fuqhaa, Firas F. Awwadi b, Salim F. Haddadb, Nabil Al-Zaqric, Fahad A. Alharthic,
Mohammed Suleimana, Abdelkader Zarroukd, Ahmed M. Boshaalae, Ismail Warad f,∗
a Department of Chemistry, Science College, An-Najah National University, P.O. Box 7, Nablus, Palestine
b Chemistry Department, Faculty of Science, The University of Jordan, Amman11942, Jordan
c Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh11451, Saudi Arabia
d Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V University, Av. IbnBattouta, Box 1014, Agdal-Rabat, Morocco
e Department of Chemistry, Faculty of Science, Benghazi University, P O Box 1308Benghazi, Libya
f Department of Chemistry and Earth Sciences, College of Arts and Sciences, Qatar University, P O Box 2713, Doha, Qatar
a r t i c l e i n f o
a b s t r a c t
Article history:
Two dicationicCu(II) complexes of [Cu(phen)(NNN)]Br2 (1-2) general formula [phen
=
1,10-
Received 4 September 2020
Revised 15 January 2021
Accepted 17 January 2021
Available online 25 January 2021
phenanthroline, NNN = diethelenetriamine (dien) (1) and dipropylenetriamine (dipn)(2)], have been
synthesized in very good yields. The two complexes were characterizedvia UV-vis., CHN-EA, MS, FT-IR,
thermal, and X-ray crystallographic techniques. XRD data for 1 showed a distorted square pyramidal Cu(II)
ions geometry center with three uncoordinated water molecules. TGA were performed to evaluate the
interactions strength and found to support the XRD molecular interactions results. The time-dependent
density functional theory (TD-DFT) and electron transfer processes were modeled, and consequently the
absorption maxima around 610 and 280 nm were attributed to d–d and Phen(π)→Phen(π٭) transitions.
Positive Gutmann’ssolvatochromismbehavior of both complexes have been recorded. Furthermore, the
ability of the two complexes for DNA binding was evaluatedvia absorption studies in the visible region
showing high Kb constant values.
Keywords:
Cu(II)
Phen
NNN-tridentate
XRD
solvatochromism, DNA
© 2021 Elsevier B.V. All rights reserved.
1. Introduction
stance, copper(II) complexes with phenanthroline chelating agent
possess hydrophilic groups that allow them to act as promising
The synthesis of 1,10-phenanthroline/metal ion complexes re-
ceived extensive attention in research due to their significant ap-
plications [1,2] as potential anti-tumor agents [3,4]. Those mixed-
ligand complexes containing nitrogen donor ligands have also
great potential in antimicrobial [1-4], antioxidant [5], anticancer,
and catalytic activities [6-9]. The photo-physical properties of
Cu(II) complexes including polypyridine ligands resulted in effec-
tive DNA binder complexes [10-15]. The anticancer effectiveness
Cu(II) complexes are categorized according to their ability to in-
hibit DNA binding [16]. The determination of the complex struc-
tures in solid-state and solutions is vital to understand the in-
telligent biological processes in biological systems [17,18]. For in-
anti-tumor agents due to their cell membrane penetration ability
[19-20].
Diethelenetriamine (dien) and dipropylenetriamine (dipn) are
N-tridentate chelate ligands which can form bi five-membered N-
M rings. Moreover, N-tridentate chelate ligands usually form din-
uclear, trinuclear and metal clusters [21]. Recently, we have in-
spected similar [Cu(N-N)(dipn)]Br2 and [Cu(bipy)dipn)].2BF4 com-
plexes in spectral and biological activities [22-28]. In this work,
our group is reporting the mixed-ligands combination of two
new dicationicCu(phen)(NNN)]Br2 complexes [NNN = diethelene-
triamine (dien) (1) and dipropylenetriamine (dipn) (2)]. The com-
plexes structural properties were spectral and the thermally moni-
tored, moreover, the crystal structure of 1 was solved, the electron
transfer was modeled by TD-DFT, and their ability for DNA binding
was evaluated.
∗
Corresponding author.
E-mail address: ismail.warad@najah.edu (I. Warad).
https://doi.org/10.1016/j.molstruc.2021.129983
0022-2860/© 2021 Elsevier B.V. All rights reserved.

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Table 1
Structure refinement and crystal data of 1.
Complex No.
Complex 1
CCDC
982731
Formula weight
Temperature
Wavelength
740.99 (C16H21Br2CuN5.Phen.3H2O)
293(2) K
˚
0.71073 A
Crystal system
Space group
Unit cell dimensions
Monoclinic
P 21/n
˚
˚
a = 12.6411(13) A, b = 19.422(3) A, β= 111.016(12)°,
˚
c = 13.7128(13) A
˚
Volume
3142.7(6) A3
Z
4
Density (calculated)
Absorption coefficient
F(000)
1.566 Mg/m3
3.279 mm-1
1500
Crystal size
0.4687 × 0.2661 × 0.2059 mm3
3.18 to 26.00°
Theta range for data collection
Index ranges
-15 ≤ h ≤ 15, -23 ≤ k ≤ 14, -15 ≤ l ≤ 16
13451
Reflections collected
Independent reflections
Completeness to theta = 27.50°
Absorption correction
Max. and min. transmission
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
6161 [R(int) = 0.0344]
99.8 %
Analytical
0.652 and 0.395
1.013
R1 = 0.0602, wR2 = 0.1408
R1 = 0.1130, wR2 = 0.1612
2. Methods
The FT-IR spectra were obtained using Perkin–Elmer 621 spec-
trophotometer. UV-Vis. spectra were determined on Pharmacia
LKB-Biochrom 4060 spectrophotometer. The melting points were
recorded using Stuart® SMP10. The MS were performed using
ThermoScientificTM TSQ AltisTM Triple Quadrupole Mass Spectrom-
eter.
2.1. Chemicals
All chemicals and solvents used were purchased from Sigma–
Aldrich.
2.2. General procedure to synthesis of [Cu(phen)(NNN]Br2 (1-2)
2.4. XRD-collection and computational details
(0.81 g, 2 mmol) of Br2Cu(phen) was suspended in 30 mL of
ethanol under ultrasound waves, 2 mmol of diethylenetriamine or
dipropylenetriamine in 10 mL of water and then were merged to
the previous solution. The reaction was stirred under ultrasound
for 8 min. until the color was turned to deep blue color. The sol-
vents were evaporated from the solution under vacuum and the
solid product was washed well using CH2Cl2 solvent then dried
under vacuum. Suitable XRD crystals of 1 have been collected via
slow evaporation of water from 1 stocksolution.
Full geometry optimization of 1 was carried out using DFT at
the B3LYP level [29]. All computations were performed using the
GAUSSIAN09 package [30]. For C, H and N the cc-pvdz basis set
were assigned, while for Cu the LanL2DZ basis set with effective
core potential were employed [31]. Vertical electronic excitations
based on B3LYP optimized geometries were computed using the
TD-DFT formalism in water using polarizable continuum model
(PCM) [32-36]. A suitable block like elongated green crystals of
1 were mounted with Epoxy on a glass fiber and the diffraction
data were collected at room temperature using an Oxford Xcal-
2.2.2. [Cu(phen)(dien)]Br2 (1)
˚
ibur diffractometer (Mo Kα radiation, λ = 0.7107 A). Data was
Yield (87 mg, 85%), m.p.
=
180°C. MS m/z 505.2
reduced and processed to give hkl files using CrysAlisPro soft-
ware [37]. The structures were solved by direct methods and re-
fined by leastsquares method on F2 using the SHELXTL program
package [38]. Carbon bound hydrogen atoms were placed in cal-
culated positions and refined isotropically using a riding model,
whereas, the six hydrogen atoms of the three water of salva-
tion were located in a difference Fourier map and were refined
isotropic ally. All non-hydrogen atoms were refined anisotropi-
{[Cu(phen)(dien)]Br2} [M+] for C16 H21Br2CuN5 Calculated: C,
37.92; H, 4.18; N, 13.82. Found C, 37.81; H, 4.10; N, 14.62%, IR (KBr,
νcm−1): 3460(vH2O), 3380 and 3280, (vH-N), 3120 (vC-H of phenyl),
2800-2950 (vC-H), 1580 (vN-H), 1160 (vN-C), 620 and 540 (vCu-N).
UV–Vis in water: λmax (εmax/ M−1cm−1): 282 (1.6 × 103), 610
(3.5 × 102).
2.2.3. [Cu(phen)(dipn)]Br2 (2)
cally. Highest peak and deepest hole are 0.949 and −0.503 e/
Yield (96 mg, 90%), M.p. = 190°C. MS m/z 533.2 [M+] for
C18 H25Br2CuN5 Calculated: C, 40.43; H, 4.71; N, 13.10. Found C,
40.22; H, 4.64; N, 13.08%, IR (KBr, νcm−1): 3440 (vH2O), 3360
and 3270, (vH-N), 3160 (vC-H of phenyl), 2940 (vC-H), 1560 (vN-H),
3
˚
A . Details of crystal data collection and refinement are given in
Table 1.
1180 (vN-C), 610 and 520 (vCu-N).UV–Vis in water: λmax (εmax
M
/
2.5. DNA binding experiment
−1cm−1): 280 (1.4 × 103), 610 (3.0 × 102).
The DNA binding tests were performed in pH 7.4, Tris-HCl
buffer using distilled water as solvent. The DNA titration processes
with the complexes were in the visible regions at 610 nm for 1 and
at 610 nm for 2 using fixed complexes concentration 5 × 10−3M
and different DNA concentration 0–0.04M [22-28].
2.3. Physical analysis
CHN-microanalyses were done on an ElementarVarrio EL an-
alyzer. TGA were performed at TA instrument SDT-Q600 in air.
2

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Scheme 1. Synthesis of [Cu(phen)(NNN)]Br2 (1-2).
3. Result and discussion
3.1. Synthesis
[Cu(phen)(NNN)]Br2 (1-2) as dicationicCu(II) complexes have
been prepared using mixed-ligands, phen = 1,10-phenanthroline,
NNN= diethelenetriamine (dien) (1) and dipropylenetriamine
(dipn) (2)]. Reacting of [Cu(Phen)Br2] starting complex with NNN
ligands under ultrasonic revealed the formation of the desired
complexes as bromide salts with high yields (Scheme 1). The com-
plexes found to be highly stable in open atmosphere solid state,
high boiling points were recorded, moreover, these complexes are
good water soluble with blue color in both solid and aqua-states.
The complexes were characterized using MS, CHN-EA and spectral
methods (see experimental part). The XRD- structure of 1 reflected
the formation of the Cu(II) center with distorted square pyramidal
shape.
Fig. 1. FT-IR of (a) CuBr2(phen), (b) 1,and (c) 2.
3.3. Crystal structure of 1
3.1. Synthesis
3.2. IR
1 crystallized in the Monoclinic with P21/nspace group. Elected
experimental and DFT computed bond distances and angles of 1
and 2 are given in Table 2. The asymmetric unit with atomic num-
bering scheme is shown in Fig. 2.
The KBr-IR disk spectra of CuBr2(phen) starting complex was
compared to 1 and 2after triamines addition as seen in Fig. 1.
It was observed that only in 1 and 2 the stretching vibrations
at 3460 ν(O-H) and 1430 ν(bend) corresponded to H2O since water
has been detected in the lattice of the complexes. In the spectra
of the 1 and 2 (not in CuBr2(phen) complex), the three stretch-
ing vibrations at 3400-3320, 3280–3200 and 1620-1590 cm−1 as-
signed to νsN–H, νasN–H and δN–H, respectively shifted to lower
wavenumbers compared to their free triamines ligands. This ob-
servation strongly confirm that amine groups coordinated to the
Cu(II) center [39]. The stretching vibrations at 3120-3050 cm−1
is due to C-H phenylic stretching vibration, meanwhile, C-H of
sp3 hybridization alkyl stretching vibrations were sited at 2800-
As shown in the Table 2, high degrees of similarities in the an-
gles and bonds lengths of the two complexes were collected when
compared the XRD-experimental with the DFT-theoretical calcula-
tions. For complex 1, the Cu2+ ion is coordinated by two N-atoms
of the phen and three N-atoms of triene ligands, the free two Br
ions occupied the counter ion position far away from each other
yielding mixed dication [Cu(phen)(triene)]Br2 complex. The 5-fold
coordinated Cu2+ ion is in a highly distorted square pyramidal en-
vironment, the trans angles of the square base are 175.09(16)° and
155.92(15)°, the average angles between the axial atom N10, Cu1
and the equatorial atoms (base atoms; N1, N3, N4 and N5) is 97.0°
(range = 78.85(16)° – 109.66(14)°). The axial bond distance (Cu1-
N10) is 2.212(4) Ǻ. The structural features of the desired complex
in this work are very similar to [Cu(dien)(phen)](ClO4)2 reported
one [46-51], with one of the two N atoms of phen occupying the
apical site Cu-N(apical) bond distance = 2.186 Ǻ, and the other
2950 cm−1 [40-47]. Peak at
~
620 and 540 cm−1can be at-
tributed to ν(Cu-N) new bond formation [44]. A stretching vibra-
tions at 282-295 cm−1 can be cited to the ν(Cu-Br) bonds [45]
(Table 1).
3

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Table 2
˚
XRD/DFTselectedbond lengths [A] and angles [°] for 1 and 2.
˚
˚
˚
No.
Bond lengths
Exp./XRD of 1[A]
DFT of 1 [A]
DFT of 2[A]
1
2
3
4
5
Cu(1)-N(10)
Cu(1)-N(3)
Cu(1)-N(1)
Cu(1)-N(4)
Cu(1)-N(5)
2.212 (4)
2.036 (3)
2.030 (4)
2.020(3)
2.015 (4)
2.267
2.088
2.066
2.075
2.088
2.301
2.085
2.071
2.101
2.120
No.
1
Angles
Exp./XRD of 1[°]
95.66 (15)
DFT of 1 [°]
95.34
DFT of 2[°]
96.43
N(5)-Cu(1)-N(1)
N(4)-Cu(1)-N(1)
N(5)-Cu(1)-N(3)
N(4)-Cu(1)-N(3)
N(1)-Cu(1)-N(3)
N(5)-Cu(1)-N(10)
N(4)-Cu(1)-N(10)
N(1)-Cu(1)-N(10)
N(3)-Cu(1)-N(10)
N(5)-Cu(1)-N(4)
2
175.1414 (16)
155.91 (15)
84.17 (14)
171.98
155.81
83.16
172.89
155.61
83.46
3
4
5
94.00 (15)
95.39
95.43
6
109.66 (14)
105.80 (16)
78.85 (16)
101.84
109.78
78.23
108.94
107.88
78.73
7
Fig. 3. Chain structure of 1. All atoms are represented as wireframes except nitro-
8
gen atoms that areimplicated in the interactions as spheres.
9
93.83 (14)
101.54
83.19
101.84
84.02
10
84.17 (14)
3.4. UV-Vis. and TD-DFT
At room temperature, the complexes absorptions were recorded
experimentally in water then assigned with the TD-DFT method.
The spectra of the two complexes exhibit intense signals
(ε = 1.6 × 103 M−1 cm−1) around 280 nm along with a low inten-
sity band around 610 nm (ε = 3.5 × 102 M−1 cm−1). For better un-
derstanding the electronic structures, DFT stimulations have been
carried out for 1 and 2. The full geometry optimizations for the
compounds have been performed at the DFT/UB3LYP level. Some
elected optimized bond parameters for 1 are listed in Table 4. The
optimized structure parameters of the bond lengths and angles
correlated well with the XRD-data of 1. Contour plots of selected
molecular orbitals are shown in Fig. 4.
Computation of 20 excited states of 1 and 2 allowed the inter-
pretation of the experimental spectra in the range of 200–800 nm
(Fig. 5). The calculated energy of excitation states and transition
oscillator strength (f) are shown in Table 4. Based on the TD-DFT
obtained results, both the exp. UV–Vis and the corresponding DFT
simulated spectra result are in satisfactory agreement (Fig. 5). In 1,
the two observed absorption bands are due mainly to the transi-
tions from different orbitals to LUMO-α and LUMO-β. The longer
wavelength is a result of transition to LUMO-β that is mainly com-
posed mainly from Cu (58%) and triamine ligand (33%). The shorter
wavelength is due to the transition to LUMO-α which is mainly lo-
cated on phen.
Fig. 2. The ORTEP generated diagram of 1 with 50% probability displacement ellip-
soids.
Table 3
˚
Hydrogen bonds distances (A) and angles (°).
D-H
A
d(H..A)
d(D..A)
<DHA>
ꢀ
N5-H5 A
N19
N28
O1a
2.35
2.56
2.11
2.72
2.47
2.53
2.55
3.163(6)
3.287(6)
2.953(8)
3.468(4)
3.266(6)
3.242(6)
3.497(4)
152.3
140.0
157.3
142.3
149.1
137.6
161.3
ꢀ
N5-H5 A
On the basis of its intensity and position, the high intensity
and energy band at 282 nm result from the overlap of two calcu-
lated transitions 311 nm resulted from the overlap of three tran-
sitions 304.9 nm which is resulted from H-1(α) to LUMO (α)
and H-3(β) to LUMO (β), 311.2 nm resulted from H-1 to L (α)
and H-3(β) to LUMO (β) (34%) and 323.9 nm which is resulted
from H-4(β) →LUMO (β) (Table 5) thus this band is assigned as
to Phen(π)→Phen(π٭) transitions.The low intensity lowest energy
band at 610 nm resulted from the overlap of two calculated transi-
tion (512.7 m which is resulted from HOMO/-3 /-9/-10/-16(β) to L
(β) and 512.7 nm resulted from H-7/ -11/-13(β) to L(β)) thus, this
band is a assigned to a of d–d transition of Cu(II) ions which is
typical for a distorted trigonalbipyramidal coordination geometry
around copper(II) [22].
ꢀ
N5-H5 B
ꢀ
N3-H3 A
Br2
ꢀ
N3-H3 B
N19b
N28b
Br1
ꢀ
N3-H3 B
ꢀ
N4-H4 A
a
[-x+3/2, y+1/2, -z+1/2]
x-1/2, -y+1/2, z-1/2
b
basal site Cu-N(basal) bond distance = 2.022 Ǻ. The disposition
of the uncoordinated phen is basically parallel to the Cu bonded
phen with dihedral angle between the planes of both of 2.40° as
is shown in Fig. 2. The uncoordinated phenis linked to the coor-
dinated complex via N-H…N H-bonding connections. The N-H…N
bifurcated H-bonding connections parameters are listed in Table 3
(Fig. 3).
3.5. Global reactivity descriptor (GRD)
The three water molecules in the hydrated complex are hy-
drogen bonded to the two Br− ions in the asymmetric unit as is
shown in Fig. 3. The water O and Br− distances vary in distance
between 3.386 and 3.639Ǻ. The N-H…N interactions connect the
cationic complex and the free phen ligand to a chain structure in
run [101] direction.
The GRD quantum parameters such as ionization potential (I),
electron affinity (A), electronegativity (χ), hardness (ƞ), chemical
potential (μ), softness (σ), and electrophilicity (ω) of 1 and 2 were
calculated using the following equations then listed in Table 6.
I : Ionization potential = EHOMO
(1)
4

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Table 4
DFT energies and composition of selected highest occupied (H) and lowest unoccupied (L) molecular orbitals of both complexes expressed in terms of composing fragments.
Complex 1
α MO
β MO
MO
eV
phen
Cu
Triemine
MO
eV
phen
Cu
triemine
L+4
L+3
L+2
L+1
L
-0.03
-0.43
-1.18
-2.33
-2.56
-7.13
-7.51
-7.53
-8.13
-8.92
-9.14
2
80
1
17
0
L+3
L+2
L+1
L
-1.18
-2.34
-2.53
-3.88
-7.12
-7.52
-8.79
-9.77
-10.04
-10.16
-10.24
99
100
98
9
1
1
99
99
100
98
99
18
100
67
57
43
0
0
1
0
1
0
0
0
58
0
33
1
1
0
H
99
100
30
59
64
30
15
H
0
0
H-1
H-4
H-7
H-9
H-10
H-11
0
0
H-1
H-2
H-3
H-4
H-7
Complex 2
19
0
64
0
11
31
20
48
68
59
10
17
22
16
23
6
11
36
49
7
α MO
β MO
β MO
MO
eV
phen
Cu
Triemine
MO
eV
phen
Cu
triemine
L+5
L+4
L+3
L+2
L+1
LUMO
HOMO
H-1
0.02
1
90
76
1
9
L+5
L+4
L+3
L+2
L+1
LUMO
HOMO
H-1
-0.14
-0.43
-1.17
-2.33
-2.52
-3.85
-7.12
-7.52
-7.88
-8.52
-8.66
1
77
1
22
1
-0.16
-0.43
-1.17
-2.33
-2.54
-7.12
-7.33
-7.52
-8.09
-8.87
1
23
1
99
98
100
99
9
99
98
100
99
99
14
100
69
32
1
1
1
1
0
0
0
0
1
1
1
0
57
0
34
1
0
0
99
100
59
24
10
17
0
69
0
0
0
H-2
H-2
30
11
10
11
65
81
H-3
22
6
9
H-3
H-4
62
H-4
Table 5
Computed excitation energies (nm), electronic transition configurations and oscillatorstrengths (f) for the optical transitions in the
visible region of both complexestransitions with f ≥ 0.001 are listed).
A : Electron a f f inity = −ELU MO
(2)
(3)
(4)
(5)
σ : Global softness = l/2η
μ : Chemical potential = −χ
ω : Electrophilicity = μ2/2η
(6)
ꢀEgap : Energy gap = EHOMO − ELU MO
χ : Absolute electronegativity = I + A /2
(7)
(8)
(
)
As can be seen from Table 6, the GRD quantum parameters of
both complexes are much closed in their values, such seen is not
η : Global hardness = I − A /2
(
)
5

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Fig. 4. Isodensity plots of some selected MOs (α-spin and β -spin) of 1.
Table 6
GRD values for both complexes.
GRD
1
2
Low unoccupied molecular orbital
High occupied molecular orbital
Energy gap
LUMO
HOMO
ꢀEgap
-0.10282 a.u.
-0.14042 a.u.
0.0376 a.u.
1.0232 eV
3.8210eV
-0.10451 a.u
-0.13053 a.u.
0.0261 a.u.
0.7101 eV
3.5520 eV
2.8439 eV
3.1979 eV
0.35405 eV
1.4145 eV
-3.1979 eV
14.6282 eV
Ionization potential
Electron affinity
I
A
X
2.7979 eV
3.3005 eV
0.5115 eV
0.9775 eV
-3.3005 eV
10.645 eV
Absolute electronegativity
Global hardness
ƞ
Global softness
ꢁ
M
ω
Chemical potential
Electrophilicity
surprising since the different in both structures of the complexes
is very small.
3.6. Solvatochromism
The Cu(II) complexes with d9 expected to have strong John-
Teller effect that permit the performance of further solvatochromic
studies [22-29]. The desired complexes were found to have low
solubility in organic solvents; therefore, the number of solvents in-
Fig. 5. RT UV-Vis. spectra, (a) 1, (b) 2, and (c) TD-DFT of 1 and (d) 2 in water.
6

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
Fig. 6. Solvatochromism spectra: (a) Abs. vs. λmax for 1, (b) Abs. vs. λmax for 2, (c) AN vs. λmax for 1, (d) AN vs. λmax for 2, (e) DN vs. λmax for 1, and (f) DN vs. λmax for 2.
troduced in this study was limited to five. The type of solvent re-
sulted in the observation of different values for ƛmax in both com-
plexes, for instance, acetonitrile showed ƛmax at 585 nm, methyl
acetate at 600 nm, water at 610 nm, DMF at 625 nm, and DMSO
at 640 nm for complex 1 as illustrated in Fig. 6a. For complex 2
acetonitrile showed ƛmax at 560 nm, methyl acetate at 602 nm,
water at 610 nm, DMF at 647 nm, and DMSO at 680 nm as illus-
trated in Fig. 6b. In order to learn more about the solvatochromism
behavior of the desired complexes, Gutmann’s relations have been
established. No clear regular relation was observed by plotting AN
solvents numbers versus the changes in ƛmax values (Fig. 6c for 1
and Fig. 6d for 2). Meanwhile plotting DN solvents values against
ƛmax values, resulted in a linear appositive relationship with a cor-
relation factor R2 = 0.9412 as seen in Fig. 6e for 1 and R2 = 0.9495
as seen in Fig. 6f for 2. It is evident that, both complexes have sim-
ilar solvatochromism behavior the d-d bands were shifted with in-
creasing solvents DN values with bathochromic pattern (red shift),
therefore, the complexes are expected to have a Lewis acid behav-
iors.
3.7. TGA investigation
The TGA behavior of 1 was investigated as seen in Fig. 7. The
TG/DTA curves were performed in a temperature range of 0–900
°C and at 5 °C/min heating rate under RT atmosphere. The TGA
analyses of 1reflected a process of degradation occurring in 3 con-
secutive steps: dehydration, de-structuring of the N-ligands and
metal-oxide formation. The dehydration of the uncoordinated wa-
ter molecule was the first step recorded at 95-120 °C with TDTA
at 110 °C (endothermic sign) and 8% mass lost. The de-structuring
of the phen and triamine ligands was the second step occurred in
180-480 °C range with 40% mass lost and TDTA at 250 and 480
°C (both exothermic), moreover, this step ended by naked CuBr2
complex formation. Oxidation of CuBr2 complex to Cu=O with 23%
7

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
DNA and the aromatic rings in complexes. The extension of the
hypochromism usually reflected the presence of the intercalative
binding. The absorption of 5 × 10−3 M of 1 in Tris–HCl buffer re-
vealed bands at 620 and 280 nm. At the visible 610 nm absorption
band CT-DNA titration was performed as seen in Fig. 8I. Upon in-
cremental addition of 1.00 × 10−5–0.04 M DNA, the band shows
sufficient decay in absorption accompanied (Fig. 8II).
In order to compare quantitatively the strength of binding of
the desired complexes, the calculated Kb intrinsic binding con-
stant was determined by controlling the changes in absorbance
with increasing concentration of DNA using the following equa-
tion: [22,23].
The Kb for 1is found to be 4.6 × 104 M−1 (Fig. 8III), whereas
2 showed similar DNA binding behavior with slightly less Kb value
(4.1 × 104
M
−1). These results are comparable to those previously
Fig. 7. TGA of 1.
recorded for similar Cu(II) complexes [51]. The results suggested
a strong intercalation of such complexes with double helix of the
DNA as cis-plat mode of coordination [51-54].
4. Conclusion
Two dicationic mixed-ligand triamine/1,10-phenanthroline/
Copper(II) complexes were synthesized in excellent yields under
ultrasonic mode of vibration. The disconnection of 2Br from
CuBr2(phen) by dien or dipn N-tridentate ligand from the internal
coordination sphere to the outer sphere was monitored by UV-
visible, IR, and confirmed by XRD. The XRD results for 1 showed
that Cu(II) center is coordinated to 5 N-donor (phen and tri-
amine) ligands with two Br counter ions salt in a highly distorted
square pyramidal shape. The self-assembly of 1 indicated that
the N(π)…N interactions play a considerable part in stabilizing
the final three-dimensional structure. The absorption behaviors of
the prepared complexes in water were modeled by TD-DFT. The
solvatochromism showed positive Gutmann’s relationship with
several DN solvents. The desired complexes exhibited a strong
DNA binding; the absorption spectral Kb constant values are in
similar complexes ranges.
Author statement
All persons who meet authorship criteria are listed as authors,
and all authors certify that they have participated sufficiently in
the work to take public responsibility for the content, including
participation in the concept, design, analysis, writing, or revision
of the manuscript.
Declaration of Competing Interest
The authors declare that they have no conflicts of interest.
Acknowledgement
Fig. 8. a) Electronic spectral titration of
1 with CT-DNA at 620 nm in Tris-HCl
buffer; [1] = 5 × 10−3; [DNA]: (a) 0.0, (b) 1.0 × 10−4, (c) 4.0 × 10−4, (d) 8.0 × 10−4
,
,
(e) 1.0
×
10−3
,
(f) 3.0
×
10−3
,
(h) 6.0
×
10−3
,
(i) 1.0
×
10−2
,
(j)2.0
×
10−2
(k)4.0 × 10−2M. The arrow denotes the gradual decrease of the complex concen-
tration upon DNA addition. b) Absorption plot against [DNA] to confirm the expo-
nential decreasing relation at 620 nm. c) Plot of [DNA]/(εa- εf)vs. [DNA] for the
absorption titration of DNA with the 1.
Researchers Supporting Project number (RSP-2020/160), King
Saud University, Riyadh, Saudi Arabia.
mass occurred in range of 500 to 710 °C temperature with exother-
mic step at TDTA = 680 °C. The Cu=O copper oxide final product
was supported by IR analysis [22-28].
References
[1] S. Chandra, L.K. Gupta, Sangeetika. Spectrochim.Acta, Part
453–460.
A 62 (2005)
[2] K.P. Balasubramanian, K. Parameswari, V. Chinnusamy, R. Prabhakaran,
K. Natarajan, Spectrochim.Acta, Part A 65 (2006) 678–683.
[3] K.P. Balasubramanian, R. Karvembu, R. Prabhakaran, V. Chinnusamy, K. Natara-
jan, Spectrochim.Acta, Part A 68 (2007) 50–54.
3.8. DNA binding properties of 1: Electronic spectral
The electronic absorption spectroscopy was used to study pos-
sibility of the complex-DNA binding [52-55]. The complexes readi-
ness to bind the DNA usually results in bathochromism and
hypochromismwhich depend on the nature of the intercalative in-
teractions including ring stacking between the base pairs of the
[4] T. Rosu, E. Pahontu, C. Maxim, R. Georgescu, N. Stanica, A. Gulea, Polyhedron
30 (2011) 154–162.
[5] P. Sathyadevi, P. Krishnamoorthy, M. Alagesan, K. Thanigaimani,
P.Thomas Muthiah, N. Dharmaraj, Polyhedron 31 (2012) 294–306.
[6] K.M. Vyas, R.G. Joshi, R.N. Jadeja, C.R. Prabha, V.K. Gupta, Spectrochim.Acta,
Part A 84 (2011) 256–268.
8

M. Fuqha, F.F. Awwadi, S.F. Haddad et al.
Journal of Molecular Structure 1231 (2021) 129983
[7] R. Karvembu, S. Hemalatha, R. Prabhakaran, K. Natarajan, Inorg. Chem. Com-
mun. 6 (2003) 486–490.
[32] P.J. Hay, W.R. Wadt, J. Chem. Phys. 82 (1985) 270–283.
[33] R. Bauernschmitt, R. Ahlrichs, Chem. Phys. Lett. 256 (1996) 454–464.
[34] M.K. Casida, C. Jamorski, K.C. Casida, D.R. Salahub, J. Chem. Phys. 108 (1998)
4439–4449.
[8] G.D. Frey, Z.R. Bell, J.C. Jeffery, M.D. Ward, Polyhedron 20 (2001) 3231–3237.
[9] F. Mevellec, S. Collet, D. Deniand, A. Reliquet, J.C. Meslin, J. Chem. Soc., Perkin
Trans. 1 (2001) 3128–3131.
[10] D.S. Sigman, A. Mazumder, D.M. Perrin, Chem. Rev. 93 (1993) 2295–2316.
[11] A. Sigel, H. Sigel (Eds.), Metal Ions in Biological Systems Proving of Nucleic
Acids by Metal Ion Complexes of Small Molecules, Marcel Dekker, New York,
1996.
[35] R.E. Stratmann, G.E. Scuseria, M.J. Frisch, J. Chem. Phys. 109 (1998) 8218–
8224.
[36] M. Cossi, N. Rega, G. Scalmani, V. Barone, Comput. Chem. 24 (2003) 669–681.
[37] CrysAlisPro, Agilent Technologies, Version 1.171.35.11 (release 16-05-2011
CrysAlis171 .NET) (compiled May 16 2011).
[12] D.R. McMillin, K.M. McNett, Chem. Rev. 98 (1998) 1201–1220.
[13] K.E. Erkkila, D.T. Odom, J.K. Barton, Chem. Rev. (1999) 2777–2796.
[14] J. Leiter, J.L. Hartwell, J.S. Kahler, I. Kline, M.J. Shear, J. Natl. Cancer Inst. 14
(1963) 365–409.
[38] G.M. Sheldrick, Structure determination software suite, Bruker AXS Inc., Madi-
son, WI, 2000.
[39] G.A. Gazzani, A. Papetti, G. Massolini, M. Daglia, J. Agric. Food Chem. 46 (1998)
4118–4122.
[15] C. Krishnamurty, L.A. Byran, D.H. Petering, Cancer Res. 40 (1980) 4092–4099.
[16] R.J. Sorenson, Chem. Br. 16 (1984) 1110–1113.
[40] S. Destri, M. Pasini, W. Porzio, F. Rizzo, G. Dellepiane, M. Ottonelli, G. Musso,
F. Meinardi, L. Veltri, J. Lumin. 127 (2007) 601–605.
[17] P. Kopf-Maier, H. Kopf, Chem. Rev. 87 (1987) 1137–1152.
[18] S.E. Scherman, S.J. Lippard, Chem. Rev. 87 (1987) 1153–1181.
[19] M.J.Chare, P.C.Hydes, in:H.Sigel (Ed.), Metal Ion in Biological Systems, vol. 2,
Marcel Dekker, New York, 1980, pp. 1–62.
[41] P. Vijayan, P. Vijayaraj, P. Setty, C. Hariharpura, A. Godavarthi, S. Badami,
S D.Arumugam, Bhojraj Biol. Pharm. Bull. 24 (2004) 528–530.
[42] C. Tsiamis, M. Themeli, Inorg. Chim.Acta 206 (1993) 105–115.
[43] K. Nakamoto, Infrared and Raman spectra of Inorganic and Coordination Com-
pounds, 4th edn., J. Wiley & Sons: NY, 1986.
[20] K. Takamiya, Nature (London) 185 (1960) 190–191.
[21] M. Al-Noaimi, A. Nafad, I. Warad, R. Alshwafy, A. Husein, W.H. Talib,
T.Ben Hadda, SpectrochimicaActa Part A: Molecular and Biomolecular Spec-
troscopy 122 (2014) 273–282.
[44] A. Cassol, P. Di Bernardo, R. Portanova, M. Tolazzi, G. Tomat, P. Zanonato, J.
Chem. Soc., Dalton Trans. (1992) 469–474.
[45] R.N. Patel, N. Singh, K. Shukla, J. Niclos-Gutierrez, A. astineiras,
[22] M. Al-Noaimi, M.I. Choudhar, F.F. Awwadi, W.H. Talib, T. Ben Hadda, S. Yousuf,
A. Sawafta, I. Warad, SpectrochimicaActa Part A: Molecular and Biomolecular
Spectroscopy 127 (2014) 225–230.
[23] K. Hema, I. Warad, S. Karthik, A. Zarrouk, K. Kumara, J. Pampa, P. Mallu,
K. Lokanath, J. Mol. Struct. 1210 (2020) 128000–128010.
V.G. Vaidyanathan, B.Unni Nair, SpectrochimicaActa Part
268.
A 62 (2005) 261–
[46] N. Al-Zaqri, K.S.M. Salih, F.F. Awwadi, A. Alsalme, F.A. Alharthi, A. Alsyahi, A. Al
Ali, A. Zarrouk, M. Aljohani, A. Chetouni, I. Warad, J. Coord. Chem. 73 (2020)
3236–3248.
[24] I. Warad, F.F. Awwadi, B. Abd Al-Ghani,
A
Sawafta, N. Shivalingegowda,
[47] R.N. Patela, N. Singha, K.K. Shuklaa, J. Niclos-Gutierrez, A. Castineirasb,
N.K. Lokanath, M.S. Mubarak, T. Ben Hadda, A. Zarrouk, F. Al-Rimawi,
A.B. Odeh, S.A. Barghouthi, Ultrasonics Sonochem. 48 (2018) 1–14.
[25] I. Warad, S. Musameh, A. Sawafta, P. Brandão, C.J. Tavares, A. Zarrouk,
S. Amereih, A. Al Ali, R. Shariah, Ultrasonics Sonochem. 52 (2019) 428–432.
[26] F.A. Saleemh, S. Musameh, A. Sawafta, P. Brandao, C.J. Tavares, S. Ferdov,
A. Barakat, A. Al Ali, M. Al-Noaimi, I. Warad. Arab. J. Chem. 10 (2017) 845–855.
[27] N. Al-Zaqri, K.S.M. Salih, F.F. Awwadi, A. Alsalme, F.A. Alharthi, A. Alsyahi, A. Al
Ali, A. Zarrouk, M. Aljohani, A. Chetouni, I. Warad, J. Coord. Chem. 73 (2020)
3236–3248.
V.G. Vaidyanathanc, B.U. Nairc, SpectrochimicaActa Part
268.
[48] G. Andara, F. Fortes-Revilla, C. Snejko, N. Gutierrez-Puebla, E. Iglesias,
M. Monge, M. A, Inorg. Chem. 45 (2006) 9680–9968.
[49] F.F. Awwadi, D. Willett, D. Twamley, Cryst. Growth Des. 7 (2007) 624–632.
[50] F.F. Awwadi, D. Willett, K. Peterson, B. Twamley, J. Phys. Chem. A 111 (2007)
2319–2328.
A 62 (2005) 261–
[51] E. Lindner, S. Al-Gharabli, I. Warad, H.A. Mayer, S. Steinbrecher, E. Plies,
M. Seiler, H. Bertagnolli, Anorg. Allg. Chem. 629 (2003) 161–171.
[52] I. Warad, H. Suboh, N. Al-Zaqri, A. Alsalme, F.A. Alharthi, M.M. Aljohani,
A. Zarrouk, RSC Adv. 10 (2020) 21806–21821.
[28] M.K. Hema, C.S. Karthik, N.K. Lokanath, P. Mallu, A. Zarrouk, K.S.M. Salih,
I. Warad, J. Mol. Liq. 315 (2020) 113756–113762.
[29] T. Hadda, A. Ali, V. Masand, S. Gharby, T. Fergoug, I. Warad, Med. Chem. Res.
22 (2013) 1438–1449.
[53] S.K. Maiti, M. Kalita, A. Singh, J. Deka, P. Barman, Polyhedron 184 (2020)
114559–114566.
[30] M.El Faydy, F. Benhiba, B. Lakhrissi, M.Ebn Touhami, I. Warad, F. Bentiss,
A. Zarrouk, J. Mol. Liq. 295 (2019) 111629–111645.
[54] Z. Afsan, T. Roisnel, S. Tabassum, F. Arjmand, Bioorg. Chem. 94 (2020)
103427–103438.
[31] M.J. Frisch, G.W. Trucks, H.B. Schlegel, Gaussian 09, Revision A.1, Gaussian Inc,
Wallingford CT, 2009 Gaussian: Pittsburgh, PA.
[55] R. Kalarani, M. Sankarganesh, G.G.V. Kumar, M. Kalanithi, J. Mol. Struct. (2020)
127725–127732.
9