Synthesis, structural, optical and anti-rheumatic activity of metal complexes derived from (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) with Ru(III), Pd(II) and Zr(IV)

Article abstract of DOI:10.1016/j.saa.2014.09.064

Three new metal complexes derived from Pd(II), Ru(III) and Zr(IV) with (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) have been synthesized. The isolated complexes were characterized by elemental analyses, FT-IR, UV-Vis, ES-MS, ¹H NMR, XRD, thermal analyses (TGA and DTA) and conductance. The morphology and the particle size were determined by transmittance electron microscope (TEM). The results showed that, the ligand coordinates to Pd(II) in the enol form, while it coordinates to Ru(III) and Zr(IV) in the keto form. A square planar geometry is suggested for Pd(II) complex and octahedral geometries are suggested for Ru(III) and Zr(IV) complexes. The optical band gaps of the isolated complexes were measured and indicated the semi-conductivity nature of the complexes. The anti-inflammatory and analgesic activities of the ligand and its complexes showed that, Ru(III) complex has higher effect than the well known drug "meloxicam".

Full text of DOI:10.1016/j.saa.2014.09.064

Accepted Manuscript
Synthesis, structural, optical and anti-rheumatic activity of metal complexes
derived from (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide
(2-AAB) with Ru(III), Pd(II) and Zr(IV)
Nasser Mohammed Hosny, Yousery E. Sherif
PII:
S1386-1425(14)01422-X
http://dx.doi.org/10.1016/j.saa.2014.09.064
SAA 12740
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomo-
lecular Spectroscopy
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Accepted Date:
31 July 2014
11 September 2014
18 September 2014
Please cite this article as: N.M. Hosny, Y.E. Sherif, Synthesis, structural, optical and anti-rheumatic activity of metal
complexes derived from (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) with Ru(III),
Pd(II) and Zr(IV), Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2014), doi: http://
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Synthesis, structural, optical and anti-rheumatic activity of metal complexes
derived from (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide
(2-AAB) with Ru(III), Pd(II) and Zr(IV)
Nasser Mohammed Hosny *1, Yousery E. Sherif2,3
1Chemistry Department, Faculty of Science, Port-Said University, 23 December Street, Port-Said,
Egypt
2Department of Chemistry, Faculty of Science and Arts, Ulla, Taibah University, KSA.
3Clinical Pharmacology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt
ABSTRACT
Three new metal complexes derived from Pd(II), Ru(III) and Zr(IV) with (E)-2-amino-N-(1-(2-
aminophenyl)ethylidene)benzohydrazide (2-AAB) have been synthesized. The isolated complexes
1
were characterized by elemental analyses, FT-IR, UV-Vis., ES-MS, HNMR, XRD, thermal
analyses (TGA and DTA) and conductance. The morphology and the particle size were determined
by transmittance electron microscope (TEM). The results showed that, the ligand coordinates to
Pd(II) in the enol form, while it coordinates to Ru(III) and Zr(IV) in the keto form. A square planar
geometry is suggested for Pd(II) complex and octahedral geometries are suggested for Ru(III) and
Zr(IV) complexes. The optical band gaps of the isolated complexes were measured and indicated
the semi-conductivity nature of the complexes.
The anti-inflammatory and analgesic activities of the ligand and its complexes showed that, Ru(III)
complex has higher effect than the well known drug "meloxicam".
Keywords: Ru(III); Pd(II); Zr(IV); Metal complexes; Anti-inflammatory activity
________________________________________________________________________
*Corresponding author:
Tel.:00201208949300
E-mail: Nasserh56@yahoo.com
1

Introduction
Hydrazones are considered one of the most important classes of compounds from the
inorganic and biological point of view. They have thermal, mechanical, electrical and magnetic
properties. Also, hydrazones have non-linear optical and liquid-crystal properties [1-4]. These
properties made them the subject of wide applications in analytical chemistry, in synthesizing novel
heterogeneous catalysts in redox processes and in molecular semi-conductors [5]. Besides that,
hydrazones and their coordination compounds have been investigated widely in medicine,
especially as anti-tuberculosis, anti-tumor, anti-hypertensive and peripheral vasodilator agents [6-
10]. Anti-inflammatory studies indicated that, hydrazones derivatives have lower side effects
compare with the non-steroidal anti-inflammatory drugs (NSAIDs) [11-12].
In this work we synthesized new metal complexes of Pd(II), Ru(III) and Zr(IV) with
(E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB). The isolated complexes
have been characterized by different techniques to elucidate the structure. To shed more light on the
potential applications of the present compounds, the optical band gaps of the complexes have been
measured. Also, the analgesic and anti-inflammatory activities of (2-AAB) and its metal complexes
have been studied and compared with meloxicam.
Experimental
The chemicals used were of analytical grade and were used without further purification.
Conductvity was carried out on YSI model 32 conductivity bridge. The metal ions were determined
by standard methods [13]. The elemental analyses, C, H and N were carried out on Thermo
Scientific Flash 2000 Analyzer. IR spectra were carried out on a Mattson 5000 FTIR spectrometer
by using KBr discs. UV-visible spectra were taken by UV2 Unicam UV/vis spectrometer by using
1 cm silica cell. TGA and DTA were measured on a Shimadzu model 50 H device, the flow rate of
o
nitrogen is 20 cm3/min. and the heating is 10 C/min. JEOL spectrophotometer (500 MHz) was
2

1-
used to measure H-NMR spectra by using TMS as reference and DMSO-d6 as solvent. TEM
images of the products were obtained by CM20PHILIPS electron microscope. XRD measurements
were carried out on a D2PHASER Bruker diffractometer using CuKα radiation (λ = 1.540598 Å).
The microcrystalline samples were ground in an agate mortar, and then deposited in silicon sample
holder equipped with a zero-background plate. Diffraction data were collected in the 2θ range of
5-40°, with 0.02° steps.
Synthesis of (E)-2-Amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB)
0.02 mol (4.8 ml) of 2-aminoacetophenone was injected to 0.02 mol (3.0 gm) of
2-aminobenzohydrazide in 25 ml ethanol. The reaction was refluxed for 6 hrs. Yellow crystals were
formed. The precipitate was filtered under vacuum then, washed with ethanol and kept under
vacuum. % Yield 85, M Wt = 269.325; Found, Calcd. for C15H17N4O: C, 66.3; H, 6.9; N, 21.0
1
Calcd: C, 66.8; H, 6.3; N, 20.8%. H NMR (DMSO-d6): δ/ppm 2.34 (s, 3H, CH3-), 6.28 (s, 2H,
NH2-), 6.51 (s, 2H, NH2-), 6.71-7.58 (m, 8H, C6H4) and 10.64 (s, 1H, NH-).
Synthesis of Zr (IV) complex
To 0.01 mol (2.86 gm) of (E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide
(2-AAB) in 25 ml ethanol, 0.01 mol (1.41 gm) of ZrCl4 was injected and refluxed under nitrogen
for 6 hrs. A yellow precipitate was isolated. The precipitate was filtered under vacuum then, washed
with ethanol and kept under vacuum.
% Yield 74; M. Wt = 525.388; Found, Calcd. for [Zr(C15H17N4O)Cl4]0.5EtOH: C, 36.2; H, 3.4; N,
10.1; Zr, 16.8%. Calcd: C, 36.6; H, 3.8; N, 10.7; Zr, 17.3%. 1H NMR (DMSO-d6): δ/ppm 2.30 (s,
3H, CH3-), 6.10 (s, 2H, NH2-), 6.41 (s, 2H, NH2-), 6.68-7.82 (m, 8H, C6H4) and 10.60 (s, 1H, NH-).
Synthesis of Pd(II) complex
0.01 mol (2.94 gm) of Na2PdCl4 in 10 ml distilled water was added to 0.01 mol (2.86 gm) of
(E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) in 25 ml ethanol. The
reaction was refluxed for 4 hrs. An orange precipitate was formed. The precipitate was filtered
under vacuum and washed with ethanol and finally kept under vacuum.
3

% Yield 78; M. Wt = 539.77, Anal. Calc. for [Pd(C15H16N4O)Cl H2O]2H2O: C, 38.8; H, 4.7; N,
12.1; Pd, 20.6%. Found: C, 39.2; H, 5.0; N, 12.5; Pd, 19.7 %. 1H NMR (DMSO-d6): δ/ppm 2.43 (s,
3H, CH3-), 6.51 (s, 2H, NH2-), 6.71 (s, 2H, NH2-), 7.10-7.91 (m, 8H, C6H4).
Synthesis of Ru(III) complex
0.01 mol (2.6 gm) of RuCl3.3H2O in 10 ml ethanol was added to 0.01 mol (2.86 gm) of
(E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) in 25 ml ethanol. The
reaction was refluxed for 4 hrs. A dark green precipitate was isolated. The precipitate was filtered
under vacuum then, washed with ethanol and kept under vacuum.
% Yield 83; M Wt = 547.01. Found. Calcd. [Ru(C15H17N4O).3Cl.H2O]2.5H2O: C, 32.8; H, 4.6; N, 9.7;
Ru, 19.0%. Found: C, 33.2; H, 4.4; N, 10.3; Ru, 18.5%
Pharmacological studies
The anti-inflammatory was carried out by carrageenan induced rat hind paw edema method
on Sprague-Dawley rats (200–250 g). The animals were divided into two main groups [arthritic
group (n = 36) and control of non arthritic (n = 6)] [14,15]. Gastric tube once daily was used to give
orally the tested compounds for seven days. Paget's table was used to calculate the dose [16]. The
experiments and animal care were carried out according to NIH guide to the care and use of
laboratory animals. The study was approved by the local ethical committee. The compounds were
suspended in 0.5% sodium carboxymethyl cellulose [SCMC] mg per 200 g of rat weight because of
the insolubility of the compounds. The analgesic activity of the tested compounds was determined
by measuring right paw pad pressure tolerance at the 7th day of the compound administration (52
days after complete Freund’s adjuvant injection). Analgesimeter (Ugo Basile, Italy) was used to
apply pressure on the rat pad of the right paw.
Results and discussion
The isolated complexes are stable in air, colored, soluble in DMF and DMSO but insoluble
in water and common organic solvents. The molar conductivity values of 1x10-3 molar in DMF at
25◦C are in the range 5.0-10.0 Ω-1cm2mol-1. The conductivity values indicate non-conducting nature
4

of the compounds [17]. The ligand (2-AAB) can exist either in the keto form Fig. 1(A) or in the
enol form Fig.1 (B). Some important IR bands are collected in Table 1.
The infrared spectrum of (2-AAB) shows bands at 3480, 3458, 3366 and 3215 cm-1 assigned
to ν (NH2) of the amino groups. The bands at 1631, 1612, 1600, 1574 and 970 cm-1 can be attributed
to ν (C=O), δ (NH2), ν (C=N), ν (CONH) and ν (N-N) modes, respectively [18-20]. The presence of
the bands attributed to ν (C=O) and ν (CONH) confirms the existence of the free ligand in the keto
form.
The spectra of Zr(IV) and Ru(III) complexes exhibit bands in the region 1645-1666 cm-1
attributed to ν (C=O). The shift of these bands compared with their positions in the free ligand,
confirms the participation of this group in bonding. The presence of the band assigned to
ν (CONH) in the spectra of these two complexes suggests that (2-AAB) chelates to these metal ions
in the keto form (Figs. 2, 3 and 4). The disappearance of the bands assigned to ν (C=O) and
ν (CONH) in the spectrum of Pd(II) complex together with the appearance of a new band at 1608
cm-1 assigned to ν (C=N)* indicates the enolization of the carbonyl group. The enolic carbonyl is
deprotonated after coordination. The band suggested to the azomethine group ν (C=N) is shifted in
all the metal complexes, indicating the participation of this group in bonding. Also, the shift to
higher frequency of the band at 970 cm-1 assigned to ν (N-N) supports the participation of
azomethine group as an active site. The new weak bands in the regions 440-489 and 530-570 cm-1
can be assigned to ν (M-N) and ν (M-O), respectively [21]. The appearance of weak bands in the
regions 684-699 cm-1 and 744-786 cm-1 attributed to ρw (OH) and δ(OH), respectively confirms the
presence of water or ethanol molecules in the complexes [22].
1
The H-NMR spectrum of the ligand (Fig. 5), in DMSO-d6 shows singlet signal at 10.64
ppm of -NH amidic protons. Another singlet signal is observed at 2.34 ppm assigned to CH3
protons. The singlet signals at 6.28 and 6.51 ppm are attributed to the protons of NH2 groups. These
signals are overlapped with the aromatic protons. The aromatic protons appear as multiplet in the
region 6.51-7.58 ppm.
5

The 1H-NMR spectrum of Zr(IV) complex, in DMSO-d6 shows a broad singlet signal in the
downfield region at 10.60 ppm, corresponds to –NH of the amidic group (CO–NH). The presence
of this signal confirms the coordination of the ligand in the keto form. The broadening of this
singlet signal was attributed to the presence of intramolecular hydrogen bond [23]. The aromatic
protons appear as multiplet in the region. 6.68-7.82 ppm.
The 1H-NMR spectrum of Pd(II) complex (Fig. 6), in DMSO-d6 shows the disappearance of
the signal at 10.64 ppm, corresponding to the protons of -NH amidic in the free ligand spectrum.
The disappearance of this signal confirms the coordination of the ligand to Pd(II) in the enol form.
The two singlet signals assigned to the two NH2 protons remain in its position as the free ligand,
confirming the remaining of these groups inert towards coordination.
Mass spectra
The exact mass of the ligand (2-AAB) appears at m/z = 269.1, which matches with the
formula C15H17N4O.
Mass spectrum of Pd(II) complex shows the molecular ion peak at m/z = 463, in agreement
with the formula [Pd(C15H16N4O)ClH2O]2H2O. The molecular ion loses the three molecules of
water successively, leading to the three peaks at m/z = 446, 428 and 410, respectively. When the
molecular ion loses the fragment C6H4(NH2)CCH3, it gives the peak at m/z =317. The peak at
m/z = 410 is fragmented by loss of Cl giving the base peak at m/z = 374, which corresponds to
[PdL] species. The base peak loses aniline molecule and gives the ion peak at
m/z = 237. The fragmentation pattern of [Pd(C15H16N4O)ClH2O]2H2O is indicated in Scheme 1.
The mass spectrum of Zr(IV) complex (Fig. 7) shows the exact mass at m/z = 525.2, corresponding
to the molecular formula [Zr(C15H17N4O)Cl4]1/2EtOH. Two possible pathways in the fragmentation
pattern of Zr(IV) complex have been suggested. In the first pathway, the molecular ion loses half
molecular of ethanol and ZrCl4 giving the base peak at m/z = 296, corresponding to the free ligand.
The possible fragments of the free organic ligand and Zr(IV) complex are indicated in Scheme 2.
6

In the second pathway, the molecular ion peak loses amino group and Cl2 to give the peaks at
m/z = 509 and 437, respectively. The ion peak at m/z = 410 is fragmented by loss of CH3 and Cl
giving the ion peak at m/z = 382. The latter peak loses NH2 and C2H2 to give the peak at
m/z = 346, which further loses methane molecule leading to the peak at m/z = 330. The peak at 330
loses the fragment CH3C2 and gives the peak at m/z = 291.
Mass spectrum of Ru(III) complex shows the molecular ion peak at m/z = 542 which
corresponds to the formula [Ru(C7H17N4O)Cl3H2O]2.5H2O. Two possible path-ways have been
suggested for the fragmentation of Ru(III) complex as indicated Scheme 3. In the first pathway, the
molecular ion peak loses three and half molecules of water and three Cl leading to the peak at
m/z = 369 corresponding to [RuL]. This peak losses Ru, C6H4(NH2)C and CH3 to give the base
peak at m/z = 161. Another path way could be followed for the fragmentation of [RuL] peak at
m/z = 369 by loss of two amino and methyl groups giving the ion peak at m/z = 323. The peak at
m/z = 323 is fragmented to produce the peaks at m/z = 269 and 244 by loss of C2H2 and C4H4,
respectively. The molecular ion peak can follow a second fragmentation pathway by loss of two
water molecules and three Cl in five successive steps to give the peaks at m/z = 523, 505, 471, 435
and 400 respectively.
Thermal analysis
Thermo-gravimetrical analyses (TGA and DTA) of the complexes were measured from
◦
◦
room temperature (25 C) to 1000 C. These measurements shed light on the thermal stability of the
complexes. Thermo-gravimetrical results are presented in Table 2.
TGA and DTA curves of Ru(III) complex shows that, it loses two and half molecules of hydrated
water. This step takes part from 25 to110 ˚C (Exp., 8.9, Calcd. 8.3%), followed by loss of one
molecule of water of coordination and 3Cl in an endothermic step from110 to 240 ˚C, (Exp., 21.8,
Calcd. 23.0 %) then, methyl group and chloride ion in the range 240-270 ˚C (Exp., 8.0, Calcd. 9.3
%). The organic moiety C6H4CNH2 is lost within 270-305 ˚C (Exp. 15.6, Calcd. 16.9%). Finally,
7

the remaining of the organic ligand (C6H4C2NH2NNH) decomposes in the range 305-570 ˚C (Exp.
24.1, Calcd. 26.7%), leaving Ru2O3 as a residue (Exp. 21.6, Calcd. 23.0%)
The thermogrames (TGA and DTA) of Pd(II) complex indicates that, it dissociates from 25
to 120 ˚C by losing the out of coordination sphere water molecules, followed by loss of one
coordinated water molecules (120-210 ˚C) (Exp., 4.1, Calcd. 3.9%). The third step is an
endothermic one (210-275 ˚C) and corresponds to the loss of Ph and Cl (Exp., 25.1, Calcd. 24.0%).
The next step corresponds to loss of the moiety PhNH2 in the range 275-375 ˚C (Exp. 20.9, Calcd.
19.8%). Finally, the remaining of the organic ligand (NH2, CO, N2 and CH3) is lost in the range
375-600 ˚C (Exp. 22.2, Calcd. 21.3 %). The residue is expected to be PdO (Exp. 26.9, Calcd. 26.3
%).
The thermograms of Zr(IV) complex shows that, it loses half molecule of ethanol from 25
to104 ˚C (Exp. 3.9, Calcd. 4.4%). The next step (104-285 ˚C) is an endothermic and corresponds to
the loss of 2Cl2 and PhNH2 (Exp. 43.3, Calcd. 44.8%). The final step (320-665 ˚C) corresponds to
the loss of the remaining organic moiety PhNH2CCH3NNHC (Exp. 32.80, Calcd. 33.7%), leaving
ZrO2 as a residue (Exp. 20.0, Calcd. 23.6%)
The thermodynamic parameters of Pd(II), Ru(III) and Zr(IV) complexes were calculated by
applying Coats-Redfern [24] procedure and the values are collected in Table 3.
The activation energy E was calculated from the graphical relation (Fig. 8), the enthalpy of
activation (∆H*), the entropy (∆S*) and the free energy of activation (∆G*) were calculated using
equations 1-3.
∆S* = 2.303 [log (Zh/KT)]R (1)
∆H* = E – RT
(2)
(3)
∆G* = ∆H* - T ∆S*
Where, Z, K and h are the pre-exponential factor, Boltzmann and Plank constants, respectively [25].
The calculations were carried out only on the second step of decomposition where, the activation
energies could not be calculated for the overlapping or unsuitable steps.
8

The relatively high activation energies (E) values indicate the strong bonding between the ligand
and the metal ions. The positive enthalpies and free energies indicate that the decomposition
processes are endothermic and non-spontaneous, respectively. The complexes have more ordered
structure than the decomposition products as indicated from the negative ∆S* values [26]. From the
results it is clear that, Ru(III) complex is the most stable among the tested complexes, then Zr(IV)
and finally comes Pd(II) complexes.
Electronic spectra
The electronic spectrum of the ligand in DMSO shows a band in the UV region at 32362
cm-1 due to π→π* transition in the aromatic systems. Another two bands are observed at 28169 and
24570 cm-1 attributed to n→π* transitions. The later two bands are observed in the spectra of the
complexes but shifted to higher frequencies as a result of the coordination of the ligand to the metal
ions [27].
The absorption spectrum of Ru(III) complex in DMSO exhibits two bands at 23202 and
2
2
2
16666 cm-1 assigned to T2g→4T1g and T2g→4T2g, A1g transitions, respectively. These bands are
characteristics of octahedral Ru(III) complexes [28, 29]. The band at 28653 cm-1 is attributed to
LMCT. Two other bands are observed at 28735 and 32788 cm-1 due to the organic ligand
transitions.
The spectrum of Pd(II) complex in DMSO shows a band at 21231 cm-1 assigned to LMCT.
The bands at 28818 and 33003 cm-1 are attributed to the ligand transitions.
The electronic spectrum of Zr(IV) complex in DMSO shows a band at 23923 cm-1 assigned
to LMCT. The two bands at 27932 and 32573 cm-1 are attributed to the transitions inside the
organic ligand.
X-ray powder diffraction (XRD)
Figure 5 shows the XRD patterns of Pd(II), Ru(III), and Zr(IV) complexes. It is clear that,
Pd(II) and Zr(IV) complexes are crystalline while, Ru(III) complex is amorphous. The unit cell
parameters of Pd(II) compound was detected by Winplotr software package [30] and showed that
9

Pd(II) complex crystallizes in monoclinic crystal with the space group P21/c, a =17.0, b = 8.1, c =
11.8 Å. α = 90, β = 104.77 and γ = 90°. XRD has been treated by the simulated annealing
technique in Endeavour 1.7b [31] and the final refinements were carried out by Pawley refinement.
Weighted profile R-factor (Rwp) value was (8.16) confirmed good agreement between the calculated
and the experimental data.
The crystal structure showed three dimensional frameworks are formed through hydrogen bonding
and the Pd(II) ions form 1D chains as indicated in Fig. 9. Some geometrical parameters (Table 4)
obtained from XRD were compared with that obtained for the optimized structure by PM3 method
(Fig. 10). The possibility of interactions and hydrogen bonding between neighboring molecules are
not taken in consideration in case of PM3 calculations, it may be the reason for the differences in
values between the calculated by PM3 and that determined from XRD.
From the XRD data it is clear that, the C10-O1 bond length (1.410 Å) is larger than the ketonic
C=O by 0.18 Å; however it is in the same range as the enolic C-O. This observation confirms the
coordination of the ligand to Pd(II) ion in the enol form. The bond lengths of Pd-O1 (1.9755 Å) and
Pd-N1 (1.9555 Å) are in the same range as that reported for corresponding crystal structure of
similar donors [32]. The Pd-Cl bond length is larger than that reported for similar structure [33], due
to the participation of Cl in hydrogen bonding [33]. The angles, N1-Pd-O1 and O1-Pd-O2 are
83.0o and 173.84°, respectively. The deviation from the angles 90 and 180° of the normal square-
planar structure may be resulted from the participation of water oxygen in hydrogen bonding and
the presence of steric hindrance of the aromatic amino groups of the neighbor molecules.
Morphological characterization
Because of the influence of the particle size and morphology on the properties of materials,
the transmittance electron microscope (TEM) images of the isolated complexes were investigated.
Figs. 11A, B and C, shows the TEM images of Ru(III), Pd(II) and Zr(IV) complexes,
respectively. It is clear that, the shape of Ru(III) particles are overlapped spheres with average size
442 nm. The particles of Pd(II) complex have rod like shape with length in the range 1.3-11.8 µm
10

and width 151-371 nm. The particles of Zr(IV) complex are irregular slides with average size 4-25
µm and average width 4 µm, respectively. It is clear that, Ru(III) complex has the smallest particle
size and the more regular shape among the three complexes.
Optical band gap
Chromophores containing transition metals have been investigated widely because of their
nonlinear optical (NLO) properties [34]. Studying the conductivity properties of metal-organic
species gives them potential applicability in molecular electronics, sensors, optoelectronic devices
and organic transistors [35, 36].
In this study the optical band gaps of Pd(II), Ru(III) and Zr(IV) complexes were determined from
the electronic absorption spectrum of these complex in DMSO. The absorption coefficient (α) was
calculated from the measured absorbance (A) by applying the relation α = 1/d ln A (1) where, d
is the width of the cell. The optical band gap energy (Eg) is calculated from the relation:
αhν = A (hν- Eg)m
(2), where m equal to 2 and 1/2 for direct and indirect transitions,
respectively, A is an energy independent constant [37, 38]. By plotting (αhν)2 vs. hν and by
extrapolating the linear part of the curve to (α hν)2 = 0, the direct band gap was determined. The
curves (Fig. 12) indicate the band gap values (Eg) are 3.15, 3.22 and 3.31 eV for Pd(II), Ru(III) and
Zr(IV) complexes, respectively. These values suggest that these complexes are semi-conductors.
Comparing the values of (Eg) with that of highly efficient photovoltaic materials clarifies that the
present complexes are potential compounds for harvesting solar radiation in solar cell devices [39].
Anti-inflammatory and analgesic activities of (2-AAB) and its complexes
An in-vivo pharmacological evaluation of the ligand (2-AAB) and its Ru(III), Pd(II) and
Zr(IV) complexes was carried out to asses their potential anti-inflammatory and analgesic activities.
The results of this study (Table 3) showed that, the animals treated by meloxicam, (2-AAB), and
Ru(III) complex reduces the inflammation comparing with the arthritic non-treated group. These
compounds recorded a significant activity in lessening the rheumatoid index (RI) against the
11

arthritic non-treated group, while Pd(II) and Zr(IV) complexes produced non-significant change of
the rheumatoid index (RI) against the arthritic non-treated group.
The analgesic effect increases in groups of animals treated with Pd(II), Zr(IV) and Ru(III)
complexes as compared with that of the arthritic non-treated group. It is worthnoting that Ru(III)
complex treated group has a better analgesic effect than meloxicam. On the other hand, the ligand
(2-AAB), Pd(II) and Zr(IV) complexes produced non-significant change of pain tolerance compared
with that of the arthritic non-treated group.
The highest anti-rheumatic activity of Ru(III) complex compared with the other investigated
compounds could be attributed to its regular spherical shape and smallest particles size which is
expected to facilitate its transportation through the cell membrane.
Conclusion
Literature survey showed no work and no pharmacological assay have been carried out on
(E)-2-amino-N-(1-(2-aminophenyl)ethylidene)benzohydrazide (2-AAB) and its Pd(II), Ru(III) and
Zr(IV) complexes. The ligand (2-AAB) can coordinate to the investigated metal ions either in the
keto or in the enol form. Optical band gap measurements showed that the isolated complexes are
semi-conductors and can be used as harvesting material in solar cell devices.
The anti-inflammatory activity showed that, Ru(III)complex has the highest anti-inflammatory
activity among the tested compounds. New complexes of the second and / or the third transition
series with hydrazone moiety are expected to be potent anti-rheumatic agents.
Acknowledgment
The author Dr. Nasser M. Hosny acknowledges Prof. Jorge A. Navarro, Inorganic Chemistry
Department, Granada University and the Centro de Instrumentacion Cientifica, Granada
University, Spain for carrying out some of the analyses.
12

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14

O
OH
N
N
N
H
N
CH3
NH2
CH3
NH2
NH2
NH2
(B)
(A)
Fig. 1. (A) Keto, (B) enol tautomeric forms of the ligand
15

Cl
Cl
H2N
Cl
Zr
Cl
O
N
1/2EtOH
NH
CH3
NH2
Fig. 2. Suggested structure of Zr(IV) complex
16

Cl
OH2
Cl
H2N
Cl
Ru
O
N
2.5H2O
NH
CH3
NH2
Fig. 3. Suggested structure of Ru(III) complex
17

NH2
*
CH3
NH2
N
N
O
2H2O
Pd
Cl
OH2
Fig. 4. Suggested structure of Pd(II) complex
18

Fig.5. 1H-NMR spectrum of the ligand
19

Fig.6. 1H-NMR spectrum of Pd(II) complex
20

NH2
*
CH
NH2
3 N
-H2O
-H2O
-H2O
N
O
m/z =428
m/z = 446
m/z = 410
2H2O
Pd
-Cl
NH2
Cl
OH2
*
Me
NH2
N
CH3
NH2
N
O
Pd
m/z = 374
-NH3
-CCH3
-PhNH2
m/z = 273
m/z = 317
m/z = 330
Scheme 1. Fragmentation pattern of Pd (II) complex
21

Cl
Cl
Cl Zr Cl
O
N
C
-NH2
-Cl2
NH CH3
H2N
m/z = 509
1/2EtOH
m/z =437
-CH3
NH2
m/z =382
m/z =525
-NH2
-C2H2
-ZrCl4
-1/2EtOH
m/z =364
-CH4
(1)
-(1)
m/z =1201
O
N
C
m/z =330
-CH3C2
NH CH3
H2N
(2)
-2NH2+CH3
m/z =221
m/z =269.1
m/z =291
NH2
-HC=C=CH-
m/z =154
m/z =192
-(2)
Scheme 2. Fragmentation pattern of Zr(IV) complex
22

Fig.7. ES-MS of Zr(IV) complex
23

NH2
NH2
-2NH2
-CH3
H3C
H3C
NH2
HN
N
NH2
HN
N
m/z = 323
-C2H2
-3.5H2O
-3Cl
O
O
2.5H2O
Cl Ru Cl
Cl OH2
Ru
m/z = 369
m/z = 269
-C4H4
-C6H4NH2
-CH3
-Ru
m/z =542
-H2O
m/z = 161
NH2
m/z =523
-H2O
m/z =244
O
H
N
C
N
m/z =505
-Cl
m/z =120
-Cl
-Cl
m/z =471
m/z =435
m/z =400
m/z = 135
m/z =150
Scheme 3. Fragmentation pattern of Ru (III) complex
24

1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
-3.0
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
1000/T
Fig. 8. Coats-Redfern plot for the second stage of the thermal decomposition of Pd(II) complex
25

Fig.9. Crystal packing viewed along c axis, indicating 1D chains of Pd (II) in dark green color
26

Fig.10. Representation of the molecular structure of Pd(II) complex
27

(A)
28

(B)
29