Perchlorate mixed-ligand copper(II) complexes of β-diketone and ethylene diamine derivatives: Thermal, spectroscopic and biochemical studies

Article abstract of DOI:10.1016/j.saa.2007.02.011

The present work carried out a study on perchlorate mixed-ligand copper(II) complexes which have been synthesized from ethylenediamine derivatives (3a-c) and β-diketones. These complexes, namely [Cu(DA-Cl)(acac)H₂O]ClO₄ 4, [Cu(DA-Cl)(bzac)H₂O]H₂O.ClO₄ 5, [Cu(DA-OMe)(acac)H₂O]ClO₄ 6, [Cu(DA-OMe)(bzac)H₂O]ClO₄ 7, [Cu(DA-H)(acac)H₂O]2H₂O.ClO₄ 8 and [Cu(DA-H)(bzac)H₂O]ClO₄ 9 (where acac, acetylacetonate and bzac, benzoylacetonate) were characterized by elemental analysis, spectral (IR and UV-vis) and magnetic moment measurements. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E, A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats-Redfern equation. The biochemical studies showed that, the diamines 3a-c have powerful effects on degradation of DNA and protein. The antibacterial screening demonstrated that, the diamine (DA-Cl), 3b has the maximum and broad activities against Gram +ve and Gram -ve bacterial strains.

Full text of DOI:10.1016/j.saa.2007.02.011

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Spectrochimica Acta Part A 68 (2007) 1278–1286
Perchlorate mixed–ligand copper(II) complexes of ␤-diketone and ethylene
diamine derivatives: Thermal, spectroscopic and biochemical studies
Usama El-Ayaana,∗, Nashwa M. El-Metwallya, Magdy M. Youssefa, Serry A.A. El Bialyb
a Department of Chemistry, Faculty of Science, Mansoura University, Mansoura 35516, Egypt
b Department of Pharmaceutical Organic Chemistry, Faculty of Pharmacy, University of Mansoura, Mansoura 35516, Egypt
Received 24 December 2006; received in revised form 2 February 2007; accepted 7 February 2007
Abstract
The present work carried out a study on perchlorate mixed–ligand copper(II) complexes which have been synthesized from ethylenediamine
derivatives (3a–c) and ␤-diketones. These complexes, namely [Cu(DA-Cl)(acac)H2O]ClO4 4, [Cu(DA-Cl)(bzac)H2O]H2O.ClO4 5, [Cu(DA-
OMe)(acac)H2O]ClO4 6, [Cu(DA-OMe)(bzac)H2O]ClO4 7, [Cu(DA-H)(acac)H2O]2H2O.ClO4 8 and [Cu(DA-H)(bzac)H2O]ClO4 9 (where acac,
acetylacetonate and bzac, benzoylacetonate) were characterized by elemental analysis, spectral (IR and UV–vis) and magnetic moment measure-
ments. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analysis and evaluation of
kinetic parameters (E, A, ꢀH, ꢀS and ꢀG) of all thermal decomposition stages have been evaluated using Coats–Redfern equation. The biochemical
studies showed that, the diamines 3a–c have powerful effects on degradation of DNA and protein. The antibacterial screening demonstrated that,
the diamine (DA-Cl), 3b has the maximum and broad activities against Gram +ve and Gram −ve bacterial strains.
© 2007 Elsevier B.V. All rights reserved.
Keywords: Ethylene diamine derivatives; Thermal degradation kinetics; Biochemical; DNA; Antibacterial
1. Introduction
to posses antibacterial [8–13] antifungal [10–13] DNA bind-
ing [14] and antitumor activities [15,16]. In the presence of a
co-oxidant or under aerobic conditions a cleavage of the DNA
was observed in several cases. These studies could lead to the
development of artificial restriction enzymes or antitumor drugs.
In present work, we study the synthesis, spectroscopic, bio-
chemical and thermal behavior of six perchrolate mixed–ligand
copper(II) complexes containing ␤-diketonates (dike) (where
dike = acac, acetylacetonate or, bzac, benzoylacetonate) and
diamines (diam) of general formula [Cu(dike)(diam)H2O]ClO4.
Therefore, three novel diamine ligands namely 2-amino-1-
benzylamino-1-phenylethane.2HCl, (DA-H) 3a, 2-amino-1-
benzylamino-1-(4-chlorophenyl)ethane.2HCl, (DA-Cl) 3b,
2-amino-1-benzylamino-1-(4-methoxyphenyl)ethane. 2HCl,
(DA-OMe) 3c were prepared in a search for new diamine-copper
complexes, the structural analogues of 1, of antitumor activity.
The vicinal 1,2-diamine functional group represents the
structural unit of a number of bioactive compounds such as
peptide antibiotics, vitamin H, antitumor agents and opioid
receptor agonists [1]. In addition, 1,2 diamines function as
chiral building blocks [2] and bidentate ligands [3] for tran-
sition metals in asymmetric synthesis. Antitumor properties of
cisplatin (cis-diamminedichloroplatinum) were serendipitously
discovered by Rosenberg in the mid 1960s [4]. Its success in
antitumor chemotherapy brought about the synthesis of many
diamine-platinum complexesin asearch fordrugs havinggreater
activity, less toxicity, and to circumvent drug resistance that may
develop in certain tumors [5]. Among the 1,2-diaminoplatinum
complexes described, several possess higher antitumor activ-
ity than cisplatin [6]. Some 1,2-diaminoplatinum compounds,
either used clinically or at an advanced stage of testing, are
depicted in Scheme 1 [7]. Moreover, Schiff bases such as 1,
which is a structural analogues of 1,2-diamines, were reported
2. Experimental
2.1. Instrumentation and materials
∗
Corresponding author. Current address: Department of Chemistry, College
of Science, King Faisal University, P.O. 1759, Hofuf 31982, Saudi Arabia.
Tel.: +966 553901011; fax: +966 35886437.
All starting materials were purchased from Fluka, Riedel
and Merck and used as received. Elemental analyses (C, H
E-mail address: uelayaan@kfu.edu.sa (U. El-Ayaan).
1386-1425/$ – see front matter © 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2007.02.011

U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
1279
Scheme 1.
and N) were performed on a Perkin-Elmer 2400 Series II Ana-
lyzer. Electronic spectra were recorded on a UV-UNICAM
2001 spectrophotometer using 10 mm pass length quartz cells
at room temperature. Magnetic susceptibility was measured
with a Sherwood Scientific magnetic susceptibility balance at
297 K. Infrared spectra were recorded on a Perkin-Elmer FT-
IR Spectrometer 2000 as KBr pellets and as Nujol mulls in
the 4000–200 cm−1 spectral range. 1H and 13C NMR measure-
ments at room temperature were obtained on a Jeol JNM LA
300 WB spectrometer at 250 MHz, using a 5 mm probe head
in CDCl3. HRMS spectra were recorded on a JEOL JMS-700
apparatus. Thermogravimetric (TG) and differential (DTG) ther-
mogravimetric analysis were performed on a DTG-50 Shimazu
instrument at heating rate of 10 ◦C/min.
2.2.1.2. 2-Benzylamino-2-(4-chlorophenyl)acetonitrile (2b).
According to the general procedures 4-chlorobenzaldehyde
(14.06 g, 100 mmol) and benzylamine (10.72 g, 100 mmol) give
1
2b as oil (23.40 g, 91%). νmax (CCl4)/cm−1 2231, 3332; H
NMR (250 MHz; CDCl3) 1.96 (br, NH), 3.89 (q, J 13.1, CH2),
4.63 (s, CH), 7.23–7.42 (m, Ar-H); 13C NMR (62.9 MHz;
CDCl3) 51.1, 52.7 (CH2, CH), 118.3 (CN), 127.7, 128.3, 128.6,
128.7, 129.0, 133.3, 134.9 and 138.0.
2.2.1.3. 2-Benzylamino-2-(4-methoxyphenyl)acetonitrile (2c).
According to the general procedures, 4-methoxybenzaldehyde
(13.62 g, 100 mmol) and benzylamine (10.72 g, 100 mmol)
gave 2c was obtained as a yellow oil (22.46 g, 89%); νmax
1
(CCl4)/cm−1 2240, 3340; H NMR (250 MHz; CDCl3) 1.86
(br, NH), 3.70 (CH3), 3.87 (q, J 13.1, CH2), 4.58 (s, CH),
6.82–7.38 (m, Ar-H); 13C NMR (62.9 MHz; CDCl3) 51.0,
52.8, 55.2 (CH3, CH2, CH), 119.0 (CN), 114.2, 126.9, 127.5,
128.3, 128.5 (2C), 138.3, 159.9. Anal. Calcd for C16H16N2O:
C, 76.16; H, 6.39; N, 11.10. Found: C, 75.95; H, 6.38; N,
11.40.
2.2. Synthesis of diamine ligands
2.2.1. General procedures of Strecker synthesis
Benzaldehydes (1) (0.1 mol) was added to a solution of
sodium bisulfite (10.4 g, 0.1 mol) in water (100 mL) and the
mixture was stirred for 20 min at room temperature till the
benzaldehyde-bisulfite adduct is formed as a crystalline solid.
An aqueous solution of benzyl amine was added dropwise to the
above suspension over 20 min to give the corresponding imine.
A solution of KCN (6.5 g, 0.1 mol) in water (30 mL) was added
and the mixture was stirred for 2 h at room temperature. The
product was extracted with ethyl acetate and the organic layer
was washed with water, dried (MgSO4) and concentrated to give
the aminonitrile 2 in excellent yield (Fig. 1).
2.2.2. General procedures of catalytic hydrogenation
Nitrile (2) (50 mmol) in absolute ethanol (250 mL) contain-
ing dry HCl (10 g, 0.27 mol) was hydrogenated over 10% Pd–C
catalyst in an autoclave for 2–5 h at room temperature. After the
completion of reaction the solution was filtered through celite
pad and washed twice with absolute ethanol (50 mL). The fil-
trate was concentrated to give crude product of the diamine HCl
salt 3 which was recrystallized from ethanol.
2.2.1.1. 2-Benzylamino-2-phenylacetonitrile (2a). According
to the general procedures, benzaldehyde (10.61 g, 100 mmol)
and benzylamine (10.72 g, 100 mmol) gave 2a as oil (20.0 g,
90%) νmax (CCl4)/cm−1 2240, 3346; 1H NMR (250 MHz;
CDCl3) δ: 1.86 (br, NH), 3.95 (q, J 13.0, CH2), 4.69 (s, CH),
7.27–7.52 (m, Ar-H); 13C NMR (62.9 MHz; CDCl3) 51.2, 53.4
(CH2, CH), 118.7(CN), 127.3, 127.6, 128.4, 128.6, 128.9, 129.0,
134.7 and 138.1.
2.2.2.1. 2-Amino-1-benzylamino-1-phenylethane. 2HCl (3a).
According to the general procedures, the nitrile 2a (2.22 g,
10 mmol) gave 3a as 2HCl salt (2.53 g, 86%), mp 247–250 ◦C.
νmax (CHCl3)/cm−1; 3320, 3068; 1H NMR (250 MHz; CDCl3)
δ: 1.48 (br, NH), 2.81 (dd, J = 7.3 and 12.5, 1H, H-2), 2.91 (dd,
J = 5.5 and 12.5, 1H, H-2), 3.58 (d, J = 13.1, 1H, Ha-Bn), 3.71 (d,
J = 13.1, 1H, Hb-Bn), 3.63 (dd, J = 5.5 and 7.3, H-1), 7.23–7.40
(m, Ar-H); 13C NMR (75 MHz; CDCl3) 48.9, 51.5, 64.9 (CH2,

1280
U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
Fig. 1. Synthesis of diamine ligands.
CH), 126.9, 127.3, 127.4, 128.2, 128.4, 128.5, 140.6 and 142.3.
HRMS m/z (M+): calcd for C15H14N2·2HCl, 295.05694. Found:
295.05699.
the DNA isolated from E. coli. These samples were incu-
bated for 1 h at 37 ◦C. The DNA was analysed by using
horizontal agarose gels electrophoresis. The electrophoresis was
performed using 0.7% (w/v) agarose gels in TAE buffer (5 ␮M
sodium acetate, 1 ␮M EDTA and 0.04 M Tris–HCl pH 7.9). The
agarose gels were stained with ethidium bromide (0.5 ␮g/mL)
and the DNA was visualised on a UV trans illuminator
[17].
2.2.2.2. 2-Amino-1-benzylamino-1-(4-chlorophenyl)ethane.
2HCl (3b). According to the general procedures, nitrile 2b
(2.56 g, 10 mmol) gave 3b as 2HCl salt (2.7 g, 82%), mp
240–243 ◦C. νmax (CHCl3)/cm−1: 3300 (br, NH2) 1H NMR
(CDCl3) δ: 1.53 (br, 3 H, NH&NH2), 3.55 (d, J = 13.1, lH,
Ha-Bn), 3.70 (d, J = 13 1, 1H, Hb-Bn), 3.82–3.74 (m, 1H,
H-1), 2.90 (m, 2H, Hz), 7.21–7.37 (m, 9H, Ar-H). HRMS
m/z (M+): calcd for C15H13ClN2·2HCl, 329.50200. Found
329.50207.
2.4.1.2. Polyacrylamide gel electrophoresis. Bovine serum
albumin (BSA) (3 mg) was treated with diamine ligands (3a–c)
or their metal complex (4–9) (100 ␮M) were added to Biovine
serum albumin. The reaction mixtures were incubated for 1 h
at 37 ◦C. The protein samples were analysed using vertical one-
dimensional SDS-polyacrylamide gel electrophoresis according
to the method of Laemmli [18].
The samples were prepared by adding 15 ␮L 2× SDS-gel
loading buffer (100 ␮M Tris–HCl pH 6.8, 4% (w/v) SDS, 0.2%
(w/v) bromophenol blue, 20% (v/v) glycerol, 200 ␮M DTT) and
15 ␮L protein samples and boiled for 3 min, 20 ␮L of denatured
protein samples were loaded into the gel [18].
2.2.2.3. 2-Amino-1-benzylamino-1-(4-methoxyphenyl)ethane.
2HCl (3c). According to the general procedures, nitrile 2c
(2.52 g, 10 mmol) gave 3c as 2HCl salt (2.76 g, 85%), mp
210–212 ◦C, νmax (CHCl3)/cm−1; 1609, 1517; 1H NMR
(250 MHz; CDCl3) 1.54 (br, 3 H, NH&NH2), 2.80 (dd, J = 7.2
and 12.7, 1H, H-2), 2.86 (dd, J = 5.5 and 12.7, 1H, H-2), 3.56
(d, J = 13.2, Ha-Bn), 3.70 (d, J = 13.2, Hb-Bn), 3.53–3.58 (m,
1H, H-1), 3.81 (s, 3H, OCH3), 6.89–7.31 (m, Ar-H); 13C NMR
(75 MHz; CDCl3) 48.9, 51.4, 55.3, 64.3 (CH3, CH2, CH),
114.0, 126.8, 128.2, 128.4, 128.5, 134.3, 140.7 and 158.9.
HRMS m/z (M+): calcd for C16H16N2O·2HCl, 349.07432.
Found 349.07428.
2.4.2. Determination of SOD-like activity
Diamine ligands or their complexes were assayed for activ-
ities on superoxide dismutase (SOD) enzyme according to the
method of Bridges and Salin phenazine methosulphate (PMS)
[19]. They were assayed to generate a superoxide anion radicals
at pH 8.3.
2.3. Synthesis of mixed-ligand complexes
To a solution of diamines 3a–c (0.5 mmol) in EtOH (20 mL)
was added acac or bzac (0.5 mmol). To this mixture was added
a solution of Cu(ClO4)2·6H2O (0.185 g, 0.5 mmol) in EtOH
(10 mL) and the green solution was heated under reflux for
30 min. A dilute NH4OH was added to form a green precipitate.
The green solid was washed with EtOH and dried. Elemental
analysis and magnetic moment values for all complexes are
listed in Table 1.
2.4.3. Antibacterial effect
The antibacterial investigation of the complexes was carried
out using cup diffusion technique [20]. The test was done against
the Gram-negative Pesudomonas aeruginosa (P. aeruginosa)
and Escherichia coli (E. coli) and the Gram-positive Bacillus
subtilis (B. subtilis) and Staphylococcus (Staphylococcus sp.).
The tested complexes were dissolved in dimethylsulphoxide
(DMSO) at concentration 1 mg/mL. The Luria–Bertani Agar
(LBA) medium was used. An aliquot of the solution of the
tested complexes equivalent to 100 ␮g was placed separately
in each cup. The LBA plates were incubated for 24 h at 37 ◦C
and the resulting inhibition zones were measured. DMSO,
which exhibited no antibacterial activity, was used as a negative
control.
2.4. Biological studies
2.4.1. DNA and protein electrophoreses
2.4.1.1. Agarose gels. Diamine (3a–c) or their metal com-
plexes (4–9) (100 ␮M) were added individually to 1 ␮g of

U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
1281
Table 1
Infrared spectral bands (cm−1), elemental analysis and magnetic moment of complexes 4–9
−
Complex/empirical formula
(formula weight)
ν(C O) + ␯(C C)
combination
ν(ClO4
)
ν(Cu–O) ν(Cu–N) Found (calculated) (%)
μeff (BM)
C
H
N
[Cu(DA-Cl)(acac)H2O]ClO4, 4
1557
1533
1519
1521
1523
1515
1520
1115
1117
1111
1111
1110
1110
607 293
603 291
609 289
609 303
610 300
610 297
515
513
519
525
520
517
43.79 (44.33)
5.00 (5.02)
5.02 (5.17)
1.80
1.69
1.90
1.95
1.75
1.80
C20H27Cl2CuN2O7 (541.89)
[Cu(DA-Cl)(bzac)H2O]H2O.ClO4, 5 1557
C25H31Cl2CuN2O8 (621.97)
48.00 (48.28)
46.13 (46.93)
51.88 (52.09)
43.89 (44.20)
52.66 (52.72)
4.96 (5.02)
5.47 (5.63)
5.30 (5.38)
5.88 (5.93)
5.19 (5.31)
4.39 (4.50)
5.12 (5.21)
4.54 (4.67)
5.05 (5.15)
4.88 (4.92)
[Cu(DA-OMe)(acac)H2O]ClO4, 6
21H30ClCuN2O8 (537.47)
[Cu(DA-OMe)(bzac)H2O]ClO4, 7
26H32ClCuN2O8 (599.54)
1555
1551
1558
1557
C
C
[Cu(DA-H)(acac)H2O]2H2O.ClO4,
8 C20H32ClCuN2O9 (543.47)
[Cu(DA-H)(bzac)H2O]ClO4, 9
C25H30ClCuN2O7 (569.51)
3. Results and discussion
3.1. IR spectra of mixed-ligand complexes
3.3. Thermal analysis
The stages of decomposition, temperature ranges, decompo-
sition product loss as well as the found and calculated weight
loss percentages of the complexes are given in Table 2. The TG,
DTG curves of studied complexes (Fig. 2) show either three or
four decomposition steps.
In all studied complexes the first decomposition step corre-
sponding to the loss of coordinated water in the (135–280 ◦C)
temperature range. Other decomposition steps involve the
removal of some terminal and/or integral parts in both lig-
ands. The final degradation step (centered at around 600 ◦C)
involves the removal of ClO4 ion. The high residue percentage
left without degradation in all complexes reveals the stability of
coordination sphere around the copper atom.
In order to access the influence of the structural properties
of the ligand and the type of the metal on the thermal behavior
of the complexes, the order, n, and the heat of activation E of
the various decomposition stages were determined from the TG
and DTG thermograms using the Coats–Redfern equations in
the following forms:
The main IR absorption bands for the synthesized complexes
are shown in Table 1. The observed bands may be classified
into those originated from the ligands, and those emanating
from the bonds formed between copper(II) and coordinating
sites. The bands are assigned in comparison with similar Cu(II)-
complexes. Infrared spectroscopic data suggest the coordination
of both acac (in complexes 4, 6 and 8) and bzac (in complexes
5, 7 and 9) ligands to the copper(II) centre [21]. Strong band
observed at around 1110 cm−1 (antisymmetric stretch) and the
sharp band at around 610 cm−1 (antisymmetric bend), suggest
uncoordinated perchlorate anions [22,23] in all studied com-
plexes.
3.2. Electronic spectra and magnetic moment
measurements of complexes
All complexes are insoluble in water and sparingly soluble in
most organic solvents (only soluble in DMF and DMSO), thus
the d–d transition bands of all complexes are recorded in Nujol
mulls and in DMF solutions. These electronic spectra show only
one broad band observed in the (720–740 nm) range. This posi-
tion is in favor of the square pyramidal geometry [24,25] for all
the isolated complexes in which two amine nitrogen atoms of
the diamine ligand occupy the basal plane with the two oxygen
atoms of the ␤-diketone ligand and one water molecule coor-
dinated (confirmed by thermogravimetry) in the apical position
[26].
ꢀ
ꢂ
ꢁ
1 − (1 − α)1−n
(1 − n)T2
M
T
ln
ln
=
+ B for n = 1
(1)
(2)
ꢃ
− ln(1 − α)
M
=
+ B for n = 1
T2
T
where M = −E/R and B = ln AR/ΦE; E, R, A, and Φ are the heat
of activation, the universal gas constant, pre-exponential factor
and heating rate, respectively.
Magnetic moment of complexes was observed at room tem-
perature and the data are listed in Table 1. Complexes 4, 5, 8 and
9 show μeff value in the range 1.69–1.8 BM, consistent with the
expected value for spin systems S = 1/2 with one unpaired elec-
tron (1.73 BM) in 3d9 systems. Complexes 6, 7 with magnetic
moment values of 1.90 and 1.95 BM, respectively, are typical of
“magnetically dilute” [27,28] complexes where the individual
copper(II) ions are separated from each other (no intermolecular
magnetic interaction).
The correlation coefficient, r, was computed using the least
square method for different values of n, by plotting the left-hand
side of Eqs. (1) or (2) versus 1000/T (Fig. 3). The n value which
∼
gave the best fit (r 1) was chosen as the order parameter for
=
the decomposition stage of interest. From the intercept and lin-
ear slope of such stage, the A and E values were determined.
The other kinetic parameters, ꢀH, ꢀS and ꢀG were computed
using the relationships; ꢀH = E − RT, ꢀS = R[ln(Ah/kT) − 1]
and ꢀG = ꢀH − TꢀS, where k is the Boltzmann’s constant and

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U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
Table 2
Thermal behavior of metal complexes
Compound (molecular weight)
DTG peak (◦C)
Temperature
range (◦C)
Decomposition product lost
(formula weight)
Weight (%) found
(calculated)
[Cu(DA-OMe)(bzac)H2O]ClO4 (599.54)
223
326
442
694
187–280
282–401
402–502
635–748
Residue
H2O (18.01)
OCH3 (31.03)
C2H3 (27.05)
ClO4 + CH (112.47)
C22H23O2N2Cu (410.98)
3.43 (3.01)
5.01 (5.10)
4.97 (4.50)
20.47 (19.0)
67.78 (68.39)
[Cu(DA-OMe)(acac)H2O]ClO4 (537.47)
[Cu(DA-H)(bzac)H2O]ClO4 (569.51)
[Cu(DA-H)(acac)H2O]2H2O.ClO4 (543.47)
[Cu(DA-Cl)(bzac)H2O]H2O.ClO4 (621.97)
[Cu(DA-Cl)(acac).H2O]ClO4 (541.89)
249
431
677
182–338
339–523
614–728
Residue
H2O (18.01)
OCH3 + C2H3 (58.08)
ClO4 (99.45)
3.90 (3.40)
9.29 (10.8)
19.04 (19.20)
66.9 (66.6)
C17H21O2N2Cu (348.91)
151
375
711
99–215
H2O + C3H4 (58.08)
C6H5 (77.10)
ClO4 + C (111.46)
C16H17N2O2Cu (332.86)
9.37 (10.2)
12.1 (13.5)
19.69 (18.1)
59.5 (58.2)
215–501
647–711
Residue
79
196
537
39–130
2H2O (36.02)
H2O + C4H7 (73.11)
C + ClO4 (111.46)
6.42 (6.90)
12.34 (13.5)
18.14 (20.5)
55.5 (59.1)
130–282
282–726
Residue
C
17H16O2N2Cu (343.87)
96
278
453
44–173
H2O (18.01)
3.1 (2.9)
15.5 (15.3)
19.5 (18.4)
61.3 (63.4)
175–355
357–729
Residue
H2O + C6H5 (95.12)
ClO4 + CH3 (114.49)
C18H18N2O2ClCu (393.35)
181
268
375
445
135–219
219–331
331–424
424–726
Residue
H2O (18.01)
C3H4 (40.06)
Cl + C2H3 (62.50)
ClO4 (99.45)
C15H17O2N2Cu (320.85)
3.58 (3.3)
7.62 (7.4)
10.4 (11.5)
17.5 (19.0)
61.02 (59.0)
Table 3
Temperature of decomposition, and the kinetic parameters of metal complexes
Complex
Step
T (K)
A (S−1
)
E (kJ mol−1
)
ꢀH (kJ mol−1
)
ꢀS (kJ mol−1 K−1
−0.176
)
ꢀG (kJ mol−1
)
[Cu(DA-OMe)(bzac)H2O]ClO4
1st
496
599
705
967
16,654
218.33
214.2
301.5
2nd
3rd
4th
15,807
33,375
239.9
446.9
233.99
438.9
−0.180
−0.176
360.89
609
[Cu(DA-OMe)(acac)H2O]ClO4
[Cu(DA-H)(bzac)H2O]ClO4
2nd
3rd
704
950
6,025
25,954
134
370.9
128.3
363
−0.188
−0.178
−0.174
−0.190
−0.178
260.66
532.45
1st
2nd
3rd
424
544
984
19,112
3,296
28,742
64.81
103.5
403.0
61.3
99.0
394.78
135.16
202.83
569.75
[Cu(DA-H)(acac)H2O]2H2O.ClO4
1st
353
469
662
959
11,402
4,704
153.65
95.18
50.7
150.7
91.28
45.2
−0.177
213.17
178.84
2nd
3rd
4th
−0.187
19,048
300.65
292.68
−0.181
466.27
[Cu(DA-Cl)(bzac)H2O]H2O.ClO4
[Cu(DA-Cl)(acac).H2O]ClO4
1st
369
551
725
948
19.1
67.84
113.0
443.5
16.0
63.26
106.96
435.6
2nd
3rd
4th
877
31,364
33,263
−0.202
−0.175
−0.176
−0.186
175
233.5
435.78
1st
454
541
648
944
4,707
93.65
59.0
260.46
334.16
89.88
54.57
255.69
326.3
174.5
2nd
3rd
4th
18,551
22,435
−0.178
−0.179
371
496

U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
1283
Fig. 2. TG and DTG of (a) [Cu(DA-Cl)(acac).H2O]ClO4; (b) [Cu(DA-Cl)(bzac)H2O]H2O.ClO4; (c) [Cu(DA-OMe)(acac)H2O]ClO4; (d) [Cu(DA-OMe)(bzac)H2O]
ClO4; (e) [Cu(DA-H)(acac)H2O]2H2O.ClO4; (f) [Cu(DA-H)(bzac)H2O]ClO4 complexes.
h is the Planck’s constant. The kinetic parameters are listed in
Table 3. The following remarks can be pointed out: (i) all com-
plexes decomposition stages show a best fit for (n = 1) indicating
a first order decomposition in all cases. Other n values (e.g. 0,
0.33 and 0.66) did not lead to better correlations; (ii) the value of
ꢀG increases significantly for the subsequently decomposition
stages of a given complex. This is due to increasing the values of
TꢀS significantly from one stage to another which overrides the
values of ꢀH. Increasing the values of ꢀG of a given complex
as going from one decomposition step subsequently to another
reflects that the rate of removal of the subsequent ligand will
be lower than that of the precedent ligand [29,30]. This may
be attributed to the structural rigidity of the remaining complex
after the expulsion of one and more ligands, as compared with
the precedent complex, which require more energy, TꢀS, for
its rearrangement before undergoing any compositional change;
(iii) the negative values of activation entropies ꢀS indicate a
more ordered activated complex than the reactants and/or the
reactions are slow [31]; (iv) the positive values of ꢀH mean that
the decomposition processes are endothermic.
3.4. Biochemical effect of ligand and its metal-complexes
on the DNA in vitro
The degradation effect of 100 ␮M diamines (3a, 3b and 3c)
and its copper(II) complexes (4, 5, 6, 7, 8 and 9) on the DNA

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U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
Fig. 3. Coats–Redfern plots for [Cu(DA-OMe)(bzac)H2O]ClO4, where Y = [−ln (1 − α)/T2].
is illustrated in Fig. 4. The ligands 3a and 3c have a complete
degradation on the tested DNA (Fig. 4), lanes 4 and 7, respec-
tively. Ligand 3b has less degradation effect on the DNA (Fig. 4),
lane 10. On the other hand, complexes 4–9 have weak degrada-
tion effect on the DNA compared to the control (Fig. 4), lanes 2,
3, 5, 6, 8 and 9, respectively. It is clear that the diamine ligands
(3a, 3b and 3c) have more degradation effect on the DNA than
that recorded for 4–9 complexes. Therefore, the diamines, par-
ticularly 3a and 3c can be evaluated, after more detailed study,
as degradation factor for DNA.
Further biochemical studies to illustrate the exact role of the
promising degredative effect on DNA displayed by diamines
3a–c and its Cu-complexes 4–9 were carried out. There-
fore, we decided to study the effect of these diamines and
its Cu-complexes on the protein as another important bio-
macromolecule. The effect of the parent diamine ligands (3a–c)
and their complexes (4–9) on the BSA was carried out and the
results illustrated in Fig. 5.
The diamine (DA-H), 3a and its complexes 8 and 9 have a
strong degradation effect on the BSA (Fig. 5), lanes 3–5, respec-
tively. The diamine (DA-OMe), 3c cleaves completely the BSA;
Fig. 5. Effect of 100 ␮M of the diamine ligands and their metal complexes on
the BSA protein in vitro.
Fig. 4. Effect of 100 ␮M of the diamine ligands and their metal complexes on
the DNA in vitro.

U. El-Ayaan et al. / Spectrochimica Acta Part A 68 (2007) 1278–1286
1285
Table 4
Table 5
Superoxide (SOD) like activity of the metal complex as antioxidative enzyme
Effect of metal complex on some microorganisms the results expressed as zone
inhibition in millimetre diameter
Compound
ꢀ through 5 min
% inhibition
Compound
E. coli
P. arg.
B. st.
S. st.
(DA-Cl), 3b
0.110
0.169
0.365
0.153
0.281
0.383
0.086
0.226
0.167
81.57
71.7
[Cu(DA-Cl)(acac).H2O]ClO4, 4
[Cu(DA-Cl)(bzac)H2O]H2O.ClO4, 5
(DA-OMe), 3c
[Cu(DA-OMe)(acac)H2O]ClO4, 6
[Cu(DA-OMe)(bzac)H2O]ClO4, 7
(DA-H), 3a
(DA-Cl), 3b
22
12
9
12
11
11
18
3
3
2.8
1.5
1.5
1.8
1.7
1.2
2.1
2.1
2.3
38.86
74.37
52.93
58.63
85.59
62.14
72.03
[Cu(DA-Cl)(acac).H2O]ClO4, 4
[Cu(DA-Cl)(bzac)H2O]H2O.ClO4, 5
(DA-OMe), 3c
[Cu(DA-OMe)(acac)H2O]ClO4, 6
[Cu(DA-OMe)(bzac)H2O]ClO4, 7
(DA-H), 3a
1.1
1.1
1.5
1.5
1.8
1.4
1.7
1.7
1.1
−ve
1.4
1.2
1.2
1.7
1.6
1.3
[Cu(DA-H)(acac)H2O]2H2O.ClO4, 8
[Cu(DA-H)(bzac)H2O]ClO4, 9
[Cu(DA-H)(acac)H2O]2H2O.ClO4, 8 16
[Cu(DA-H)(bzac)H2O]ClO4, 9 11
% inhibition = ((ꢀControl − ꢀTest)/ꢀControl) × 100.
and complex 9 (11 mm) for the same microorganism. On the
other hand, complexes 8 and 9 exhibit the same antibacterial
activity against P. arg. (17 mm) more than that recorded for 3a
(14 mm) against P. arg.
lane 8 (Fig. 5) while, their complexes 6 and 7 have little cleavage
effect on the BSA (Fig. 5, lanes 6 and 7, respectively). It is clear
that ligands 3a and 3c have strong degradation effect on both the
DNA and the BSA. The diamine (DA-Cl), 3b and its complex 5
have a strong degradation effect on the BSA (Fig. 5, lanes 9 and
10, respectively) while, complex 4 has less degradation effect
on BSA (Fig. 5, lane 11). It is clear that the parent ligands have
a powerful degradation effect on both DNA and BSA more that
the effect of their complexes.
Parent compounds (3c, 3a and 3b) demonstrate the presence
of a strong SOD like activity (Table 4) and this is represented in
the as inhibition percent 85.59%, 81.57% and 74.37%, respec-
tively. Also, complexes 9, 4, 8 and 6 demonstrated a considerable
SOD like activity 72.03%, 71.7%, 62.14 and 52.93%, respec-
tively. On the other hand, complexes 5 and 7 represented low
SOD like activity of 38.86% and 38.86%, respectively, as illus-
trated in Table 4. The SOD like activity of the parent ligands
indicates that these compounds can be used to prevent the for-
mation of superoxide-radical.
The diamine (DA-Cl), 3b displayed the maximum antibac-
terial activity regarding with inhibition zone diameter (30 mm
againstbothP. aeruginosaandB. subtilis, 28 mmagainstStaphy-
lococcus sp. and 22 mm against E. coli). On the other hand,
complexes 4 and 5 present low antibacterial activity compared
to their free diamine (DA-Cl). Complexes 4 and 5 have the same
antibacterial activity regarding with inhibition zone diameter
(15 mm) against Staphylococcus sp. and (11 mm) against P. arg.
Complex 4 has remarkable antibacterial against E. coli (12 mm)
compared to complex 5 (9 mm) against the same microorganism.
Also complex 4 has higher antibacterial effect against B. sub-
tilis (11 mm) in contrast; complex 5 has no antibacterial effect
against B. subtilis as illustrated in Table 5.
The free ligand 3c (DA-OMe), and its complexes 6 and
7 express a remarkable antibacterial activity against the
tested microorganisms Table 5. It shows high effect regarding
Staphylococcus sp. (18 mm) while, complexes 6 and 7 show
antibacterial effect of 17 and 12 mm against the same microor-
ganism. The inhibition zone diameter of (DA-OMe) against B.
subtilis and E. coli were 14 and 12 mm, respectively, while com-
plexes 6 and 7 exhibited inhibition zone diameter of 12 and
11 mm against B. subtilis and E. coli, respectively.
4. Conclusion
A new series of copper(II) complexes were prepared and
characterized by the elemental analysis and spectral studies,
based on these studies they have been assigned square-pyramidal
geometry. TGA data support the presence of coordinated water.
Thermalanalysisareinvestigatedandshowedeitherthreeorfour
decomposition steps. The stability of complexes was explained
and kinetic parameters (E, A, ꢀH, ꢀS and ꢀG) of all thermal
decomposition stages have been evaluated using Coats–Redfern
equation.
Three novel diamine ligands are synthesized and character-
ized. These diamines show a noticeable effect as antibacterial
andDNA-degradativeaction“whichmaybeasignforanti-tumor
activity” even much higher than the recorded with their copper
complexes.
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