Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity

Article abstract of DOI:10.1016/j.saa.2014.02.014

Two new hydrazone ligands, H₂L¹ and H ₂L², were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, ¹H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO ^-, NO3-, SO42-, Cl^- and Br^- afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L′) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H₂L¹ ligand acts as a neutral or monobasic tridentate ligand while the H ₂L² ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H₂L¹ ligand) or isatinic oxygen (H₂L² ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.

Full text of DOI:10.1016/j.saa.2014.02.014

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Mono- and binuclear copper(II) complexes of new hydrazone ligands
derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and
antimicrobial activity
⇑
Magdy Shebl , Mosad A. El-ghamry, Saied M.E. Khalil, Mona A.A. Kishk
Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
ꢀ
Two new hydrazone ligands were
synthesized and characterized.
Copper(II) complexes were
synthesized and characterized by
analytical and spectral methods.
The spin Hamiltonian parameters of
some complexes were calculated and
discussed.
The complexes exhibited octahedral
and square planar geometrical
arrangements.
The ligands and some complexes
showed antimicrobial activity.
CH3
H
N
N
N
Ph
Ph
N
COCH3
OH
OH2
O
.1.5H2O
N
ꢀ
ꢀ
ꢀ
Cu
O
O
C
CH3
[(HL1)Cu(OAc)(H2O)].1.5H2O
a r t i c l e i n f o
a b s t r a c t
Two new hydrazone ligands, H2L1 and H2L2, were synthesized by the condensation of 4,6-diacetylresorcin-
ol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures
of the ligands were elucidated by elemental analyses, IR, 1H NMꢁR, electronic and mass spectra. Reactions
of the ligands with several copper(II) salts, including AcOꢁ, NO3 , SO42ꢁ, Clꢁ and Brꢁ afforded mono- and
binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a sec-
ondary ligand (L0) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; ben-
zoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by
elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic
susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated.
The spectroscopic data showed that the H2L1 ligand acts as a neutral or monobasic tridentate ligand while
the H2L2 ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion
are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L1 ligand) or isatinic oxygen (H2L2
ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depend-
ing on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.
Ó 2014 Elsevier B.V. All rights reserved.
Article history:
Received 2 January 2014
Received in revised form 29 January 2014
Accepted 9 February 2014
Available online 18 February 2014
Keywords:
4,6-Diacetylresorcinol
Isatin
Triazine
ESR spectra
Binary and ternary complexes
Antimicrobial activity
Introduction
antifungal and antitumor agents [1–3]. Also, they are used in
extraction of some metal ions using different buffer solutions [4],
Hydrazones and their metal complexes form an interesting class
of compounds which find extensive applications in antibacterial,
micro determination of metal ions [4], determination of titanium
in bauxite, Portland cement, amphibolites and granites [5].
Triazine is an important class of heterocyclic compounds found
in many synthetic and natural products with a wide range of
⇑
Corresponding author. Tel.: +20 233120546.
E-mail address: magdy_shebl@hotmail.com (M. Shebl).
http://dx.doi.org/10.1016/j.saa.2014.02.014
1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
233
biological activities, such as adenosine receptor antagonist [6],
antiamoebic [7], antimalarial [8], antiviral [9], antitubercular [10]
and carbonic anhydrase inhibitor [11].
Isatin is a versatile lead molecule for designing potential bioac-
tive agents and its derivatives were reported to possess a broad
spectrum of antiviral activities [12]. Ligands containing isatin moi-
ety are known to possess a wide range of pharmacological proper-
ties that include antibacterial, antifungal [13], anticonvulsant [14]
and anti-HIV [15] activities.
one, respectively in the molar ratio 1:2 (DAR:hydrazino). The liga-
tional behavior of the new ligands towards different copper(II)
salts was investigated. The structures of the ligands and their metal
complexes were characterized by elemental and thermal analyses,
IR, 1H NMR, electronic, ESR and mass spectra as well as conductiv-
ity and magnetic susceptibility measurements at room tempera-
ture. The biological activity of the ligands and their complexes
was screened against selected kinds of bacteria and fungi.
The bifunctional carbonyl compound; 4,6-diacetylresorcinol
(DAR) serves as precursor for the construction of different polyden-
tate ligands [16–20]. In our previous studies, metal complexes of
polydentate ligands derived from 4,6-diacetylresorcinol [21–27]
have been synthesized and fully characterized. The most motivat-
ing features of these ligands are the possibility of use them to syn-
thesize polynuclear complexes with different modes of bonding.
Also, mixed-ligand complexes including 4,6-diacetylresorcinol as
a primary ligand have been studied [28–30].
On the basis of stated facts, the present work is an extension to
our work and is devoted to the synthesis of new hydrazone ligands,
H2L1 and H2L2, by the condensation of 4,6-diacetylresorcinol with
3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydraz-
Experimental
Materials
4,6-Diacetylresorcinol was prepared as cited in the literature
[16]. 3-Hydrazino-5,6-diphenyl-1,2,4-triazine was prepared
according to Ref. [31] and isatin monohydrazone was prepared
according to Ref. [32]. Benzil, glacial acetic acid, thiosemicarbazide,
hydrazine hydrate and isatin were BDH or Merck products. Metal
salts, lithium hydroxide, 8-hydroxyquinoline (8-HQ), 1,10-phenan-
throline (Phen), benzoylacetone (Bac), EDTA disodium salt, ammo-
nium hydroxide, mureoxide and nitric acid were either Aldrich,
Table 1
Analytical and physical data of the hydrazone, H2L1 and H2L2, ligands and their copper(II) complexes.
a
No. Reaction
Complex M.F. [F. Wt]
Color
Yield
(%)
M.P.
(°C)
Elemental analysis, % found/(calc.)
C
H
N
Cl/S
–
M
–
H2L1
C25H21N5O3 [439.48]
Pale brown
Brown
89
83
84
50
75
60
96
71
71
>300
>300
>300
>300
281
68.46 4.7
16.1
(68.33) (4.82) (15.94)
(1) H2L1 + Cu(OAc)2ꢂH2O
(2) H2L1 + Cu(NO3)2ꢂ2.5H2O
(3) H2L1 + CuSO4ꢂ5H2O
(4) H2L1 + CuCl2ꢂ2H2O
(5) H2L1 + CuBr2
[(HL1)Cu(OAc)(H2O)]ꢂ1.5H2O C27H28N5O7.5Cu [606.1]
[(HL1)Cu(H2O)]NO3 C25H22N6O7Cu [582.04]
53.57 4.97 11.8
(53.51) (4.66) (11.55)
–
–
10.4
(10.48)
Dark green
51.66 3.8
14.56
11.0
(51.59) (3.81) (14.44)
(10.92)
[(H2L1)Cu(SO4)(H2O)2]ꢂ1.5H2O C25H28N5O10.5SCu [662.14] Brown
45.42 4.0 10.47 4.6
9.4
(45.35) (4.26) (10.58) (4.84) (9.6)
52.9 4.2 12.29 6.0 11.1
(53.19) (4.11) (12.41) (6.28) (11.26)
[(HL1)CuCl]ꢂ1.5H2O C25H23N5O4.5ClCu [564.49]
[(HL1)Cu(H2O)3]BrꢂH2O C25H28N5O7BrCu [653.98]
[(HL1)Cu(8-HQ)(H2O)] C34H28N6O5Cu [664.19]
Green
Dark green
260
45.84 4.1
(45.92) (4.32) (10.71)
10.88
–
–
–
–
9.5
(9.72)
(6) H2L1 + Cu(OAc)2ꢂH2O + 8-
Chocolate
brown
263
61.47 4.0 12.9
(61.49) (4.25) (12.65)
63.4 3.9 13.5
(63.19) (4.22) (13.23)
58.3 4.7 9.9
(58.61) (4.92) (9.76)
9.4
(9.57)
HQ
(7) H2L1 + Cu(OAc)2ꢂH2O + Phen [(HL1)Cu(OAc)(Phen)] C39H31N7O5Cu [741.27]
(8) H2L1 + Cu(OAc)2ꢂH2O + Bac [(HL1)Cu(H2O)(Bac)]ꢂ2H2O C35H35N5O8Cu [717.24]
Dark brown
267
8.4
(8.57)
Dark brown
>300
8.7
(8.86)
H2L2
C26H20N6O4 [480.49]
Brown
94
59
17
23
58
53
79
40
64
>300
>300
>300
>300
>300
>300
>300
>300
>300
64.8
4.5
17.2
–
–
(64.99) (4.2) (17.49)
(9) H2L2 + Cu(OAc)2ꢂH2O
(10) H2L2 + Cu(NO3)2ꢂ2.5H2O
(11) H2L2 + CuSO4ꢂ5H2O
(12) H2L2 + CuCl2ꢂ2H2O + LiOH
(13) H2L2 + CuBr2
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH C35H40N6O11Cu2
Dark brown
49.6 4.5 9.79
(49.58) (4.76) (9.91)
–
14.8
(14.99)
[847.83]
[(L2)2Cu2]ꢂEtOH C54H42N12O9Cu2 [1130.10]
[(L2)2Cu2]ꢂ2H2O C52H40N12O10Cu2 [1120.07]
[(L2)Cu2Cl2]ꢂH2OꢂEtOH C28H26N6O6Cl2Cu2 [740.55]
[(L2)Cu2Br2] C26H18N6O4Br2Cu2 [765.37]
Chocolate
brown
57.37 3.77 14.6
(57.39) (3.75) (14.87)
–
11.20
(11.25)
Chocolate
brown
55.57 3.92 15.4
(55.76) (3.6) (15.01)
–
11.30
(11.35)
Dark brown
45.59 3.55 11.1
(45.41) (3.54) (11.35) (9.57) (17.16)
9.3
17.0
Dark brown
40.83 2.29 10.7
(40.80) (2.37) (10.98)
–
–
–
–
16.4
(16.61)
(14) H2L2 + Cu(OAc)2ꢂH2O + 8-
[(L2)Cu2(8-HQ)2(EtOH)2] C48H42N8O8Cu2 [986.01]
Chocolate
brown
58.39 4.1
(58.47) (4.29) (11.36)
11.1
12.7
(12.89)
HQ
(15) H2L2 + Cu(OAc)2ꢂH2O + Phen [(L2)Cu2(OAc)2(Phen)2]ꢂ3H2O C54H46N10O11Cu2 [1138.12]
(16) H2L2 + Cu(OAc)2ꢂH2O + Bac [(L2)Cu2(H2O)2(Bac)2]ꢂ3H2O C46H46N6O13Cu2 [1018.00]
Brown
57.06 3.8 12.0
(56.99) (4.07) (12.31)
54.24 4.3 8.0
(54.27) (4.55) (8.26)
10.9
(11.17)
Reddish
brown
12.3
(12.48)
a
The yield is calculated on the basis of ligands.

234
M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
BDH or Merck products. Organic solvents (ethanol, absolute etha-
nol, methanol, isopropanol, diethylether, dimethylformamide
(DMF) and dimethylsulfoxide (DMSO)) were reagent grade chemi-
cals and were used without further purification.
ligands and their metal complexes was studied using the disc dif-
fusion method [34].
Synthesis of the hydrazone ligands
The hydrazone ligands were prepared in two steps. The first
step was the formation of 4,6-diacetylresorcinol (DAR) by acetyla-
tion of resorcinol [16]. The second step was the condensation of
4,6-diacetylresorcinol stoichiometrically in the molar ratio 1:2
with 3-hydrazino-5,6-diphenyl-1,2,4-triazine or isatin monohyd-
razone to give the hydrazone ligands: 1-(5-(1-(2-(5,6-diphenyl-
1,2,4-triazin-3-yl)hydrazono)ethyl)-2,4-dihydroxyphenyl)ethanone
(H2L1) and 3,30-(1,10-(4,6-dihydroxy-1,3-phenylene)bis(ethan-1-
yl-1-ylidene))bis(hydrazine-2,1-diylidene)diindoline-2-one (H2L2),
respectively (Structure 1). The use of 1:2 or 1:1 (DAR:hydrazino tri-
azine) molar ratios yielded the same product (1:1) not the desired
bis compound. The preparation method is as follows:
A solution of 4,6-diacetylresorcinol (0.5 g, 2.58 mmol) in abso-
lute ethanol or methanol (30 mL) was added to 3-hydrazino-5,6-
diphenyl-1,2,4-triazine (0.678 g, 2.58 mmol or 1.358 g, 5.16 mmol)
in absolute ethanol or isatin monohydrazone (0.831 g, 5.16 mmol)
in methanol (30 mL). The reaction mixture was heated under reflux
for 8 h which yielded brown products. The precipitate was filtered
off, washed several times with absolute ethanol or methanol then
with diethylether and finally air-dried. The H2L1 and H2L2 ligands
were recrystallized from acetic acid and methanol–DMF, respec-
tively. The crystals were dried in a desiccator over anhydrous cal-
cium chloride. The analytical and physical data for the ligands and
their metal complexes are listed in Table 1.
Measurements
Elemental analyses (C, H, N, S and Cl) were carried out at the
Microanalytical Center, Cairo University, Giza, Egypt. Analysis of
the copper(II) ion followed the dissolution of the solid complex
in concentrated HNO3, neutralizing the diluted aqueous solutions
with ammonia and titrating the metal solutions with EDTA. Melt-
ing points of the ligands and their complexes were determined
using a Stuart SMP3 melting point apparatus. IR spectra were re-
corded using KBr discs on FT IR Nicolet IS10 spectrometer. The
electronic spectra were recorded at room temperature on a Jasco
model V-550 UV/Vis spectrophotometer as Nujol mulls and/or
solutions in DMF. 1H NMR spectra were recorded using a Mer-
cury-300BB (300 MHz). Dimethylsulfoxide, DMSO-d6, was used as
a solvent and tetramethylsilane (TMS) as an internal reference.
ESR spectra of the complexes were recorded at Elexsys, E500, Bru-
ker company. The magnetic field was calibrated with a 2,20-diphe-
nyl-1-picrylhydrazyl (DPPH) sample purchased from Aldrich. Mass
spectra were recorded on GC-2010 Shimadzu Gas chromatography
instrument mass spectrometer. Samples were introduced directly
to the probe, and the fragmentations were carried out at 300 °C
and 70 eV. The magnetic susceptibility measurements were carried
out at room temperature using a magnetic susceptibility balance of
the type Johnson Matthey, Alfa product, Model No. (MKI). Effective
magnetic moments were calculated and corrected using Pascal’s
constants for the diamagnetism of all atoms in the compounds
[33]. Molar conductivities of 10ꢁ3 M solutions of the solid com-
plexes in DMF were measured on the Corning conductivity meter
NY 14831 model 441. TGA-measurements were carried out from
room temperature up to 800 °C at a heating rate of 10 °C/min on
a Shimadzu-50 thermal analyzer. The biological activity of the
Synthesis of the metal complexes
The metal salt and the ligand, both dissolved in ethanol, were
mixed in the molar ratio 1:1 in case of H2L1 ligand and 2:1 (M:L)
in case of H2L2 ligand and heated under reflux for 8 h. The resulting
precipitates were filtered, washed with ethanol then ether and
finally air-dried. The complexes were kept in a desiccator over
Table 2
Characteristic IR spectral data of the hydrazone, H2L1 and H2L2, ligands and their complexes.
No. Complex
IR spectra (cm)ꢁ1
m
m
(OH) and/or
(NH) triazine
m
(C@N)
m
(C@N)
m
(N@N)
m
(C@O)
m
(MAO)
m
(MAN) Other bands
azomethine triazine
triazine
isatin
or isatin
H2L1
3429, 3306
3425, 3254
1609
1593
1533
1505
1442
1428
–
–
–
579
–
474
1
[(HL1)Cu(OAc)(H2O)]ꢂ1.5H2O
1553
s(COOꢁ); (bidentate OAcꢁ)
1446;
(NOꢁ3 ) (ionic)
1098, 1048;
m
as(COOꢁ), 1484
m
2
3
[(HL1)Cu(H2O)]NO3
3446, 3185
3467
1595
1558
1517
1507
1433
1430
–
–
494
495
421
445
m
[(H2L1)Cu(SO4)(H2O)2]ꢂ1.5H2O
m
(SO24ꢁ)
(monodentate)
4
5
6
7
[(HL1)CuCl]ꢂ1.5H2O
3446, 3188
3447, 3187
3341, 3292
3440
1599
1595
1601
1592
1517
1516
1505
1506
1432
1427
1430
1427
–
–
–
–
570
579
513
531
418
427
446
419
[(HL1)Cu(H2O)3]BrꢂH2O
[(HL1)Cu(8-HQ)(H2O)]
[(HL1)Cu(OAc)(Phen)]
1486,
1562
m
m
(C@N) 8-HQ
as(COOꢁ), 1445
m
s(COOꢁ); (monodentate
OAcꢁ), 1540,
m
(C@N) Phen
8
9
[(HL1)Cu(H2O)(Bac)]ꢂ2H2O
3577
1589
1505
1423
–
494
462
1685,
m(C@O) Bac
H2L2
3420, 3229
1621
1592
–
–
–
–
1716
1710
–
546
–
469
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH 3417
1548
m
m
as(COOꢁ), 1486
s(COOꢁ); (bidentate OAcꢁ)
10
11
12
13
14
15
[(L2)2Cu2]ꢂEtOH
3402, 3217
1594
1594
1586
1593
1598
1586
–
–
–
–
–
–
–
–
–
–
–
–
1710
1710
1709
1693
1710
1695
577
577
550
546
519
545
469
469
459
491
492
490
[(L2)2Cu2]ꢂ2H2O
3402, 3217
3442, 3340
3435
3417
3416
[(L2)Cu2Cl2]ꢂH2OꢂEtOH
[(L2)Cu2Br2]
[(L2)Cu2(8-HQ)2(EtOH)2]
[(L2)Cu2(OAc)2(Phen)2]ꢂ3H2O
1497,
1551
m
m
m
(C@N) 8-HQ
as(COOꢁ), 1428
s(COOꢁ); (monodentate
OAcꢁ), 1520,
1670, (C@O) Bac
m(C@N) Phen
16
[(L2)Cu2(H2O)2(Bac)2]ꢂ3H2O
3440
1589
–
–
1710
510
469
m

M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
235
Table 3
Electronic spectra, magnetic moments and molar conductivity data of the hydrazone, H2L1 and H2L2, ligands and their complexes.
a
b
c
a
No.
Complex
Electronic spectral bandsa (nm) kmax (nm)/(emax
)
leff. B.M.
lcompl. B.M.
Conductance
(X )
ꢁ1 cm2 molꢁ1
H2L1
281 (0.28), 331 (0.26), 371 (0.14)
474e, 537e sh
543d
–
–
–
–
–
–
–
–
–
–
–
8.3
1
2
3
4
5
6
7
8
[(HL1)Cu(OAc)(H2O)]ꢂ1.5H2O
2.12
1.86
2.15
1.71
1.8
1.31
1.83
2.1
[(HL1)Cu(H2O)]NO3
107.4
39
34.2
84.9
7.2
[(H2L1)Cu(SO4)(H2O)2]ꢂ1.5H2O
[(HL1)CuCl]ꢂ1.5H2O
500e sh, 550e sh
538d
[(HL1)Cu(H2O)3]BrꢂH2O
[(HL1)Cu(8-HQ)(H2O)]
[(HL1)Cu(OAc)(Phen)]
[(HL1)Cu(H2O)(Bac)]ꢂ2H2O
519d sh, 566d
520d sh, 578d sh
457d, 542d
4.5
5. 2
486e, 567d
H2L2
266 (0.3), 342 (0.2), 422 (0.18)
493d, 564d
–
1.4
2.1
2.02
1.9
1.62
2.01
2.1
–
–
6.4
11
9
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH
1.66
2.57
2.6
2.54
2.07
2.67
2.74
2.8
10
11
12
13
14
15
16
[(L2)2Cu2]ꢂEtOH
530d, 600d
[(L2)2Cu2]ꢂ2H2O
530d, 600d
11
[(L2)Cu2Cl2]ꢂH2OꢂEtOH
[(L2)Cu2Br2]
589d
40.3
24.5
10
12.5
6. 2
515d
[(L2)Cu2(8-HQ)2(EtOH)2]
[(L2)Cu2(OAc)2(Phen)2]ꢂ3H2O
[(L2)Cu2(H2O)2(Bac)2]ꢂ3H2O
519d, 565d
515d, 558d
474d sh, 573d
2.12
a
b
c
Solutions in DMF (10ꢁ3 M), values of emax are in parentheses and multiplied by 10ꢁ4 (L molꢁ1 cmꢁ1).
leff. is the magnetic moment of one cationic species in the complex.
lcompl. is the total magnetic moments of all cations in the complex.
d
e
Nujol mull.
Concentrated solutions.
Table 4
1H NMR spectral data of the hydrazone ligands.
(a)
(a)
(a)
(a)
(e)
CH3
CH3
CH3
CH3
H
(b)
(d)
(b)
(d)
N
N
N
N
N
O
N
N
N
(c) Ph
O
(c)
(c)
HO
(f)
HO
(f)
N
OH
(f)
N
H
(e)
OH
(f)
N
H
O
(c)
Ph
(e)
(H2L1)
(H2L2)
dH(ppm)
Ha
Hb
Hc
Hd
He
Hf
12.58, 14.32
aromatic
H2L1
H2L2
2.57, 2.66
(6H)
6.38
(1H)
7.34–7.54 (10H)
8.08
(1H)
11.62
(1H; exchangeable with D2O)
(2H; exchangeable with D2O)
2.58, 2.66
(6H)
6.39
(1H)
6.42–8.18 (8H)
8.25
(1H)
10.77
12.61, 13.54
(2H; exchangeable with D2O)
(2H; exchangeable with D2O)
anhydrous calcium chloride. The following detailed preparations
are given as examples and the other complexes were obtained
similarly.
filtered off, washed several times with ethanol, diethylether and
finally air-dried. The yield was 0.58 g (96%).
Antimicrobial activity
Synthesis of [(HL1)Cu(OAc)(H2O)]ꢂ1.5H2O, complex (1)
About 0.182 g (0.91 mmol) of copper(II) acetate dissolved in
30 mL ethanol was added gradually to 0.4 g (0.91 mmol) of the li-
gand, H2L1, dissolved in 30 mL ethanol. The reaction mixture was
heated under reflux for 8 h which resulted a brown precipitate that
was filtered off, washed several times with ethanol, diethylether
and finally air-dried. The yield was 0.46 g (83%).
The standardized disc-agar diffusion method [34] was followed
to determine the activity of the synthesized compounds against
the sensitive organisms Staphylococcus aureus (ATCC 25923) and
Bacillus subtilis (ATCC 6635) as Gram positive bacteria, Salmonella
typhimurium (ATCC 14028) and Escherichia coli (ATCC 25922) as
Gram negative bacteria and Candida albicans (ATCC 10231) and
Aspergillus fumigatus as fungus strain. The antibiotic chloramphen-
icol was used as reference in the case of Gram-positive bacteria,
cephalothin in the case of Gram-negative bacteria and cyclohexi-
mide in the case of fungi.
Synthesis of [(HL1)Cu(8-HQ)(H2O)], complex (6)
About 0.182 g (0.91 mmol) of copper(II) acetate dissolved in
30 mL ethanol was added gradually to 0.4 g (0.91 mmol) of the li-
gand, H2L1, dissolved in 30 mL ethanol. The reaction mixture was
heated under reflux for 30 min. and then 0.132 g (0.91 mmol) of
8-hydroxyquinoline (8-HQ) dissolved in ethanol was added to
the above mixture. The resulting mixture was heated under reflux
for 8 h which resulted a chocolate brown precipitate that was
The compounds were dissolved in DMF which has no inhibition
activity to get concentrations of 100 l l
g mLꢁ1 and 50 g mLꢁ1. The
test was performed on medium potato dextrose agars (PDA) which
contain infusion of 200 g potatoes, 6 g dextrose and 15 g agar [35].
Uniform size filter paper disks (3 disks per compound) were

236
M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
impregnated by equal volume (10
l
L) from the specific concentra-
the elemental analyses (Table 1) are in good agreement with the
proposed formula. The IR spectral data of the ligands (Table 2)
showed characteristic absorption bands in the ranges 3420–3429,
3229–3306 and 1609–1621 cmꢁ1 which may be assigned to
tion of dissolved tested compounds and carefully placed on inocu-
lated agar surface. After incubation for 36 h at 27 °C in the case of
bacteria and for 48 h at 24 °C in the case of fungi, inhibition of the
organisms was measured and used to calculate mean of inhibition
zones.
m
(OH)phenolic, and
tively. The triazine ligand, H2L1, showed bands at 1533 and
1442 cmꢁ1 that may be attributed to
(C@N), (N@N) of the tri-
azine moiety, respectively [36]. Finally, the isatinic ligand, H2L2,
showed a strong band at 1716 cmꢁ1 characteristic for
(C@O) of
m(NH)triazine or isatin and m(C@N)azomethine, respec-
m
m
Results and discussion
m
the isatin moiety [13,37,38]. The electronic spectral data of the li-
gands in DMF (Table 3) showed three bands in the ranges 266–281,
331–342 and 371–422 nm. The higher energy bands may be as-
Characterization of the ligands
The structures of the ligands were elucidated by elemental
analyses, IR, electronic, 1H NMR and mass spectra. The results of
signed to
p–
pꢃ transitions of the triazine or isatin ring and C@C
Fig. 1. Mass spectra A: H2L1 ligand, B: H2L2 ligand, C: [(HL1)Cu(H2O)]NO3 (2) and D: [(L2)2Cu2]ꢂ2H2O (11).

M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
237
band. The medium energy band may be composite bands due to
charge transfer (CT) transitions involving the whole molecules as
well as
ure of the complex. These infrared spectral data were supported by
coductance data (see latter). Complex 3 showed new bands at 1098
and 1048 cmꢁ1 which may be assigned to the coordinated sulfate
group in a monodentate fashion [42]. Complexes 10 and 11 did
not exhibit new bands assigned for nitrate or sulfate anions,
respectively indicating the absence of these anions which is consis-
tent with elemental analyses (Table 1). The mode of bonding in
these complexes (10 and 11) was suggested to be 2:2 (L:M) which
was obtained in our previous work [24] for a related Schiff base li-
gand derived from 4,6-diacetylresorcinol and benzylamine where
this behavior was obtained in case of copper(II) and cerium(III)
ions. Furthermore, in our recently work including 4,6-diacetylres-
orcinol as a ligand, this mode of bonding was obtained in case of
alkaline earth metal [28], nickel(II) [29] and copper(II) [30] ions.
The mixed-ligand complexes containing 8-hydroxyquinoline (6
and 14) or 1,10-phenanthroline (7 and 15) showed new bands in
the ranges 1486–1497 and 1520–1540 cmꢁ1 (Table 2) supporting
the coordination of the C@N group of the secondary ligand to the
metal ion [21–23,26]. Similarly, the mixed benzoylacetone com-
plexes (8 and 16) showed new bands in the range 1670–
1685 cmꢁ1 due to the coordinated C@O group of benzoylacetone
p–
pꢃ transitions involving the triazine, isatin and phenyl
rings and/or azomethine groups. Finally, the lower energy band
may be attributed to n–pꢃ transitions of the azomethine groups.
1H NMR spectral data (d ppm) of the ligands relative to TMS
(0 ppm) in DMSO-d6 are listed in Table 4. The signals observed in
the range 12.58–14.32 ppm may be assigned to the hydrogen-
bonded phenolic AOH groups [13,21–23,27,28]. These signals dis-
appeared in the presence of D2O, indicating that these protons are
acidic and the hydroxyl groups can participate in the coordination
with the metal ions [25,26]. Also, signals observed at 11.62 and
10.77 ppm, which disappeared in the presence of D2O, may be as-
signed to the triazinic and isatinic ANH protons, respectively
[39,40]. Finally, the signals due to aromatic and methyl protons
are detected in the ranges 6.38–8.25 and 2.57–2.66 ppm. More-
over, the structures of the ligands were deduced from mass spec-
tral data (Fig. 1) which showed the molecular ion peaks at 439
and 481 a.m.u. for H2L1 and H2L2 ligands, respectively, confirming
their formula weights (F.W. 439.48 and 480.49 respectively).
Characterization of the metal complexes
[44]. In free benzoylacetone, the
m
(C@O) band has been reported
(C@O) band to lower wave
at 1724 cmꢁ1 [45]. Thus the shift of
m
The hydrazone ligands were allowed to react with several Cu(II)
salts of AcOꢁ, NO3ꢁ, SO24ꢁ, Clꢁ and Brꢁ in order to investigate the ef-
fect of the counterions on the products. Also, the ligands were al-
lowed to react with copper(II) ion in the presence of secondary
ligands (L0) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phe-
nanthroline or O,O-donor; benzoylacetone]. The prepared com-
plexes are stable at room temperature, non-hygroscopic and
insoluble in water and common organic solvents. The obtained
complexes are characterized by elemental and thermal analyses,
IR, electronic, ESR and mass spectra as well as conductivity and
magnetic measurements.
number supports the coordination of the C@O group to the metal
ion [44]. Finally, the above interpretation is supported by the
appearance of the new bands at 494–579 and 428–492 cmꢁ1 as-
signed to m(MAO) and m(MAN) [24–27,46–48], respectively.
Conductivity measurements
The molar conductance values of the complexes in DMF (10ꢁ3
M
solutions) were measured at room temperature and the results are
listed in Table 3. The values showed that all complexes have non
IR spectra
The IR spectral data of the complexes are listed in Table 2. Com-
parison of the IR spectra of the metal complexes with those of the
free ligands revealed that all complexes showed broad bands in the
range 3185–3577 cmꢁ1 which may be attributed to the stretching
frequency of m(NH) and/or the hydroxyl group; m(OH) of the phe-
nolic group, water or ethanol molecules associated with the com-
plexes which are confirmed by elemental and thermal analyses.
The bands at 1609 and 1621 cmꢁ1 assigned to
m
(C@N) for H2L1
and H2L2 ligands, respectively were shifted to lower wave number
in all complexes, indicating the participation of the azomethine
nitrogen in chelation. In case of H2L1 ligand, bands at 1533 and
1442 cmꢁ1 assigned to
m(C@N), m(N@N) of the triazine moiety,
respectively were shifted to lower wave number in all complexes,
indicating the participation of the triazine nitrogen in chelation.
Similarly, the band observed at 1716 cmꢁ1 characteristic for
m
(C@O) of the isatin moiety in H2L2 ligand was shifted to lower
wave number in all complexes, indicating the participation of the
isatinic oxygen in chelation [13]. In complexes 1 and 9, the chelat-
ing bidentate CH3COOꢁ group was supported by new bands ap-
peared in the ranges 1548–1553 and 1484–1486 cmꢁ1. These
two bands are due to
separation of the two bands,
m
as(COOꢁ) and
= (mas
m
m
s(COOꢁ), respectively. The
s) = 62–69 cmꢁ1, is compa-
D
m
–
rable to the values cited for the bidentate character of the acetate
group [24,29,30,41];
= 75–80 cmꢁ1. On the other hand, com-
plexes 7 and 15 showed new bands characteristic for
as(COOꢁ)
D
m
m
and m
s(COOꢁ) of acetate ion in the ranges 1551–1562 and 1428–
1445 cmꢁ1. The higher difference (117–123 cmꢁ1) between the
two bands indicates the monodentate nature of the acetate group
[42,43]. Complex 2 showed a new band at 1446 cmꢁ1 which can
be assigned to the ionic NOꢁ3 group [22,26] indicating the ionic nat-
Fig. 2. X-band ESR spectra of the complexes A: [(HL1)CuCl]ꢂ1.5H2O (4), and B:
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH (9).

238
M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
Table 5
ESR data of some copper(II) complexes at room temperature.
Complex
g
g\
A
k ꢅ 10ꢁ4 (cmꢁ1
)
G
a2
b2
k
[(HL1)Cu(H2O)3]BrꢂH2O (5)
2.19
2.17
2.06
2.03
111
113
3.17
5.7
0.56
0.53
0.89
0.85
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH (9)
electrolytic nature except complexes (2 and 5) which gave molar
conductance value = 107.4 and 84.9
ꢁ1 cm2 molꢁ1, respectively,
5 and 9 were calculated and summarized in Table 5. The room tem-
perature solid state ESR spectra of the complexes are quite similar
and exhibit an axially g-tensor parameters with g|| > g\ > 2.0023. In
axial symmetry, the g-values are related by the expression, G = (g||–
2)/(g\–2) = 4, which measures the exchange interaction between
copper centers in the solid. According to Hathaway [53,54], if the
value of G is greater than four, the exchange interaction between
copper(II) centers in the solid state is negligible, whereas when G
is lower than 4, a considerable exchange interaction is indicated
in the solid complex. The calculated G value for complex 5 is
3.17, suggesting a Cu–Cu exchange interaction while in complex
9, the value is 5.7 indicating a negligible interaction [13,30,41].
Molecular orbital coefficients, a2 (a measure of the covalency of
X
suggesting their 1:1 electrolytic nature [13,21,22,41,49]. This is
consistent with the infrared data. In case of complexes 3, 4, 12
and 13, the relatively high values of the molar conductance data
may be due to the partial dissociation in their DMF solutions, how-
ever, they did not reach the previously reported values for 1:1 elec-
trolytes in DMF solutions (ꢄ70–110)
X
ꢁ1 cm2 molꢁ1 [49].
Magnetic measurements and electronic spectra
Due to the Jahn-Teller distortion and because of the low sym-
metry of the environment around CuII-ion (d9), detailed interpreta-
tions of the spectra and magnetic properties are somewhat
complicated [50]. The magnetic moment values of the complexes
(except complexes 6 and 9) are in the range 1.62–2.15 B.M., which
is consistent with the presence of one unpaired electron [26,30,41].
In case of complexes 6 and 9, the subnormal magnetic moment val-
ues (1.31–1.4 B.M.) may be due to anti-ferromagnetic exchange;
the smallest leff values, the strongest is the exchange [51,52].
The electronic spectra of the complexes (1, 3, 5–11, and 14–16)
show two absorption bands in the ranges 457–530 and 537–
600 nm which may be assigned to the 2B1g ? 2Eg and 2B1g ? 2B2g
transitions, respectively corresponding to a distorted octahedral
geometry [26,41]. On the other hand, complexes (2, 4, 12 and 13)
show one band in the range 515–589 nm, respectively, which
may be assigned to the 2B1g ? 2A1g transition in a square planar
geometry [24,26,41,42].
the in-plane
orbitals) and b2 (covalent in-plane
by using the following equations [55].
r
-bonding between copper 3d orbital and the ligand
p-bonding), were calculated
ꢀ
ꢁ
A
3
7
k
a2
¼
þ ðgk ꢁ 2:0023Þ þ ðg? ꢁ 2:0023Þ þ 0:04;
0:036
ðgk ꢁ 2:0023ÞE
b2 ¼ ꢁ
;
8ka2
where k = ꢁ828 cmꢁ1 for the free copper ion and E is the electronic
transition energy,
a
2 = 1 indicates complete ionic character,
whereas a
2 = 0.5 denotes 100% covalent bonding, with the assump-
tion of negligibly small values of the overlap integral. The lower val-
ues of a2 (0.53–0.56) compared to b2 (0.85–0.89) indicate that the
in-plane
r-bonding is more covalent than the in-plane p-bonding.
These data are in good agreement with the data reported earlier
[13,30,41].
ESR spectra
To obtain further information about the stereochemistry and
the site of the metal ligand bonding, ESR spectra of the complexes
(4, 5 and 9) were recorded in the solid state. Fig. 2 represents the
ESR spectra of complexes 4 and 9. The spectrum of complex 4
exhibits one broad band with g = 2.09. The spectra of complexes
5 and 9 exhibit two signals at 2.19, 2.06 for the former complex
and at 2.17, 2.03 for the latter one. The shapes of the spectra of
complexes are consistent with octahedral geometry around the
Cu(II) center in complexes 5 and 9 and square planar in complex
4 [24–26,30,41]. The spin Hamiltonian parameters of complexes
Thermal analysis
Thermal gravimetric analysis (TGA) was mainly used to proof
the associated water or solvent molecules to be in the coordination
sphere or in the outer sphere of the complex [13,25,26,56]. Com-
plexes 3, 4 and 9 were taken as representative examples for ther-
mal analysis. The results of thermal analysis of these complexes
are in agreement with elemental analyses.
The thermogram of complex (3), [(H2L1)Cu(SO4)(H2O)2]ꢂ1.5H2O,
showed two stages of decomposition in the range 36–275 °C. The
first one in the range 36ꢁ143 °C, is due to the loss of one and half
uncoordinated water molecule (weight loss; Calc./Found%; 4.08/
4.46%). The second stage in the range 143–275 °C and is due to
the loss of two coordinated water molecules (weight loss; Calc./
Found%; 5.44/5.51%). The decomposition pattern of complex 3
has been explained by the reactions shown in Scheme 1.
In case of complex 4, [(HL1)CuCl]ꢂ1.5H2O, the weight loss in the
range 32–107 °C corresponds to one and half uncoordinated water
Scheme 1. Thermal degradation pattern of complex (3), [(H2L1)Cu(SO4)(H2O)2]-
ꢂ1.5H2O, in the range of 36–275 °C.
Structure 1. Structures of the hydrazone, H2L1 and H2L1, ligands.

M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
239
Structure 4. Representative structures of the ternary complexes of H2L1 ligand.
Structure 2. Representative structures of the neutral complexes of H2L1 ligand
obtained by using AcOꢁ, SO42ꢁ and Clꢁ anions.
Structure 3. Representative structures of the cationic complexes of H2L1 ligand
obtained by using NOꢁ3 and Brꢁ anions.
molecule (weight loss; Calc./Found%; 4.78/4.92%). Finally, the ther-
mogram of complex 9, [(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH
showed a weight loss in the range 27–97 °C that corresponds to
half uncoordinated water molecule as well as half uncoordinated
ethanol molecule (weight loss; Calc./Found%; 3.77/3.67%). How-
ever, the coordinated ethanol molecules are lost during the decom-
position of the complex within the next stages.
Mass spectra
The mass spectra of the complexes 2, 6, 11 and 13, as represen-
tative complexes, provide good evidence for the molecular formulas
of these complexes. Fig. 1 depicts the mass spectra of complexes 2
and 11. The mass spectra of the complexes 2, 6 and 13 showed the
highest mass peak with m/z 582, 664 and 765, respectively which
agree very well with the formula weights of the complexes
[(HL1)Cu(H2O)]NO3 (F. Wt = 582.04), [(HL1)Cu(8-HQ)(H2O)]
(F. Wt = 664.19) and [(L2)Cu2Br2] (F. Wt = 765.37). However,
Structure 5. Representative structures of the binary complexes of H2L2 ligand.
complex 11 showed the parent peak at m/z 1084 which compares
very well with the calculated formula weights of the non-hydrated
complex [(L2)2Cu2] (F. Wt = 1084.07).

240
M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
Antimicrobial studies
The antimicrobial activity of the ligands and their metal com-
plexes was investigated against the sensitive organisms S. aureus
(ATCC 25923) and B. subtilis (ATCC 6635) as Gram–positive bacte-
ria, E. coli (ATCC 25922) and S. typhimurium (ATCC 14028) as Gram-
negative bacteria, yeast: C. albicans (ATCC 10231) and fungus: A.
fumigatus. The results are listed in Table 6. Inspection of the data
given in Table 6 reveals that the ligands and their metal complexes
showed a promising activity against C. albicans while some com-
plexes are active against the Gram-positive bacteria; B. subtilis.
Few complexes showed an antimicrobial activity against S. aureus,
E. coli and A. fumigatus. Finally, the ligands and their metal com-
plexes are inactive against S. typhimurium. It is clear that H2L2 li-
gand and its complexes are more active than H2L1 ligand and its
complexes towards all organisms. Also, the activity of the ligands
is enhanced by chelation. This enhancement in activity due to che-
lation can be explained on the basis of chelation theory [57]. Che-
lation reduces the polarity of the metal ion considerably, mainly
because of the partial sharing of its positive charge with donor
groups and the possible
p-electron delocalization over the whole
chelate ring. Chelation not only reduces the polarity of metal ion,
but also increases the lipophilic character of the chelate. As a result
of this, interaction between metal ion and the cell walls is favoured
resulting in interference with normal cell processes. If the geome-
try and charge distribution around the molecule are incompatible
with the geometry and charge distribution around the pores of
the bacterial cell wall, penetration through the wall by the toxic
agent cannot take place, preventing toxic reaction within the pores
[58]. Finally, some complexes (1, 3, 9 and 13–16) seem to be prom-
ising since they showed antimicrobial activity comparable to (and
Structure 6. Representative structures of the ternary complexes of H2L2 ligand.
Finally, from the interpretation of elemental and thermal anal-
yses and spectral data (infrared, electronic, ESR and mass) as well
as conductivity and magnetic susceptibility measurements at room
temperature, it is possible to draw up the tentative structures of
the metal complexes. Structures 2–6 represent the proposed struc-
tures of the metal complexes.
Table 6
Antimicrobial activity of the hydrazone ligands and their Cu(II) complexes.
Organism
Meana of zone diameter, nearest whole mm.
Gram-positive bacteria Gram-negative bacteria
Yeasts and Fungib
Staphylococcus
aureus (ATCC
25923)
Bacillus subtilis
(ATCC 6635)
Salmonella
typhimurium
(ATCC 14028)
Escherichia coli
(ATCC 25922)
Candida albicans
(ATCC 10231)
Aspergillus
fumigatus
Concentration
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml
mg/ml mg/ml
Sample
H2L1
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
6 L
20 I
–
24 H
–
9 L
14 I
–
5 L
15 I
–
16 I
–
7 L
9 I
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
6 L
4 L
24 H
8 L
26 H
7 L
7 L
11 I
7 L
18 I
4 L
–
–
–
–
2 L
–
–
–
–
[(HL1)Cu(OAc)(H2O)]ꢂ1.5H2O (1)
[(HL1)Cu(H2O)]NO3 (2)
[(H2L1)Cu(SO4)(H2O)2]ꢂ1.5H2O (3)
[(HL1)CuCl]ꢂ1.5H2O (4)
[(HL1)Cu(H2O)3]BrꢂH2O (5)
[(HL1)Cu(8-HQ)(H2O)] (6)
[(HL1)Cu(OAc)(Phen)] (7)
[(HL1)Cu(H2O)(Bac)]ꢂ2H2O (8)
30 H
11 L
31 H
9 L
9 L
–
–
15 I
11 L
24 H
11 L
10 L
–
8 L
7 L
–
10 L
7 L
H2L2
4 L
–
–
–
–
–
–
27 H
28 H
35
2 L
–
–
–
–
–
–
20 H
21 H
26
7 L
–
–
–
–
31 H
28 H
29 H
30 H
35
4 L
–
–
–
–
20 H
20 H
24 H
23 H
25
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
6 L
–
–
–
–
4 L
–
–
–
–
7 L
5 L
21 H
8 L
14 I
10 I
20 H
23 H
23 H
18 I
28
5 L
–
–
–
–
11 L
38 H
–
–
37
3 L
–
–
–
–
8 L
31 H
–
–
26
[(L2)Cu2(OAc)2(EtOH)2]ꢂ0.5H2Oꢂ0.5EtOH (9)
26 H
14 I
20 I
13 I
27 H
28 H
29 H
25 H
35
[(L2)2Cu2]ꢂEtOH (10)
[(L2)2Cu2]ꢂ2H2O (11)
[(L2)Cu2Cl2]ꢂH2OꢂEtOH (12)
[(L2)Cu2Br2] (13)
–
–
[(L2)Cu2(8-HQ)2(EtOH)2] (14)
[(L2)Cu2(OAc)2(Phen)2]ꢂ3H2O (15)
[(L2)Cu2(H2O)2(Bac)2]ꢂ3H2O (16)
Controlc
24 I
22 I
–
20 H
20 H
–
36
28
38
27
– = No effect.
L: Low activity = mean of zone diameter 6 1/3 of mean zone diameter of control.
I: Intermediate activity = mean of zone diameter 6 2/3 of mean zone diameter of control.
H: High activity = mean of zone diameter > 2/3 of mean zone diameter of control.
a
Calculated from 3 values.
Identified on the basis of routine cultural, morphological and microscopical characteristics.
Chloramphenicol in the case of Gram-positive bacteria, cephalothin in the case of Gram-negative bacteria and cycloheximide in the case of fungi.
b
c

M. Shebl et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 126 (2014) 232–241
241
[15] S.N. Pandeya, P. Yogeeswari, D. Sriram, De.E. Clercq, C. Pannecouque, M.
Witvrouw, Chemotherapy 45 (1999) 192–196.
sometimes higher than) those of chloramphenicol, cephalothin and
cycloheximide.
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The condensation reaction of 4,6-diacetylresorcinol with 3-
hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone
afforded the hydrazone, H2L1 and H2L2, ligands, respectively. Reac-
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mononuclear complexes including neutral complexes (obtained
by using AcOꢁ, SO24ꢁ and Clꢁ anions as well as ternary complexes)
and cationic complexes (obtained by using NOꢁ3 and Brꢁ anions).
The spectroscopic data showed that the H2L1 ligand acts as a
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complex (3) in which the ligand acts as a neutral tridentate. On
the other hand, reactions of the H2L2 ligand with different cop-
per(II) salts afforded neutral binuclear complexes in which it acts
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the copper(II) ion are phenolic oxygen, azomethine nitrogen and
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