Spectroscopic characterizations and biological studies on newly synthesized Cu2+ and Zn2+ complexes of first and second generation dendrimers

Article abstract of DOI:10.1016/j.saa.2008.11.024

The novel Cu(II) and Zn(II) complexes of first and second generation poly(propylene amine) dendrimers (PPA), comprising 1,8-naphthalimde units on periphery have been synthesized. These new complexes were characterized by elemental analysis, molar conducti

Full text of DOI:10.1016/j.saa.2008.11.024

Spectrochimica Acta Part A 72 (2009) 772–782
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Spectroscopic characterizations and biological studies on newly synthesized Cu2+
and Zn2+ complexes of first and second generation dendrimers
Moamen S. Refata,∗,1, Ibrahim M. El-Deena, Ivo Grabchevb, Zeinab M. Anwerc, Samir El-Ghola
a Department of Chemistry, Faculty of Science, Port Said, Suez Canal University, Mohamed Street, 42111 Port Said, Egypt
b Institute of Polymers, Bulgaria Academy of Science, 1113-Sofia, Bulgaria
c Department of Chemistry, Faculty of Science, Ismalia, Suez Canal University, Ismalia, Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 July 2008
Accepted 15 November 2008
The novel Cu(II) and Zn(II) complexes of first and second generation poly(propylene amine) dendrimers
(PPA), comprising 1,8-naphthalimde units on periphery have been synthesized. These new complexes
were characterized by elemental analysis, molar conductivity, spectral methods (IR, 1H NMR and UV–vis
spectra) and thermal analysis (TG and DTG) techniques. From elemental analysis as well as thermal studies
it has found that the first generation dendrimer behaves as bidentate ligand and forming chelates with 1:2
(ligand:metal) and 1:4 (ligand:metal) stoichiometry for second generation dendrimer. Different kinetic
parameters namely activation energy (ꢀE*), enthalpy of activation (ꢀH*), entropy of activation (ꢀS*) and
free energy change of activation (ꢀG*) are calculated using Coats–Redfern equation. The antibacterial
activity of dendrimers and their complexes was evaluated against some Gram positive and negative
Keywords:
Dendrimer
Elemental analysis
Kinetic parameters
Antibacterial activity
bacteria.
© 2008 Elsevier B.V. All rights reserved.
1. Introduction
amines at branch point. Dendrimers can transport DNA into a large
variety of cell types and have emerged as a promising non-viral
Dendrimer chemistryexpanded rapidlybecauseit is significance
both in basic research and application [1]. Dendrimers represent a
unique class of molecules with a regular branched structure [2,3].
They are well-defined three-dimensional macromolecules [4]. In
recent years they have been receiving increased attention mainly
because of their symmetry, high degree of branching and high den-
sity of the terminal functional groups which can participate in
different reaction [5–7].
Dendrimers with electroactive groups have found applica-
tions as components in different sensors and electroluminescent
devices. On the other hand the introduction of different types
of chromophores in dendrimers macromolecules makes these
macromolecules photoactive with potential applications in pho-
tochemical molecular devices [8–12]. Some of these compounds
have also been investigated for use as biosensors [13,14]. Den-
drimers are a class of three dimension polymers suitable for a
wide rang of biomedical applications; drug delivery, RNA, DNA
and detoxication, microarray system, catalysis [15,16]. They are a
class of nanoscopic polymers with highly branched spherical struc-
ture and a unique surface of primary amines as well as tertiary
gene carrier for genetic medicines due to their safety and efficiency
[17–21].
On the other hand, the applications of 1,8-naphthalimide pos-
sessing bright color, good photostability and physiological activities
have also been widely studied. They are used in solar energy collec-
tors [22], as laser active media [23,24], as potential photosensitive
biological activity units [25], and in medicine [26]. Recently, they
have been examined in liquid crystal systems for utilization in
electro-optical devices [27–31]. Some 1,8-naphthalimide deriva-
tives which exhibit good fluorescence ‘off–on’ switching in the
presence of protons or transition metal cations can perform as flu-
orescent sensors of photoinduced electron transfer (PET) [32–36].
The results from the spectral characterization of dendrimers zero
and second generation performed in the presence of metal ions
reveal that the newly synthesized materials are highly sensitive
to Cu2+ and Co2+ this makes them reliable detectors of Cu2+ and
Co2+ ions pollution in the environment especially at industrial sites
[37].
In addition 1,8-naphthalimide was chosen as the fluorophore
component in the dendrimer molecules in view of earlier inves-
tigation into it is possible use in nanomeric PET for protons and
transition metal ions [38–40]. Obviously, the fluorescence intensity
is affected by the formation of complexes between the rare earth
metal ion and internal amido groups of PAMAM from dendrimer.
Moreover, the formation of these complexes cause a change in the
polarization of the chromophoric system that evoked by complex
∗
Corresponding author. Tel.: +20 127649416.
E-mail address: msrefat@yahoo.com (M.S. Refat).
Present address: Department of Chemistry, Faculty of Science, 888 Taif, Taif
1
University, King Saudi Arabia.
1386-1425/$ – see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2008.11.024

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773
2. Experimental
DAB-dendr-4Am, DAB-dendr-8Am dendrimers and 1,8-napht-
halic anhydride, CuCl2·4H2O, ZnCl2·6H2O and other chemicals were
purchased from Fluka, Aldrich and Merck companies, and were used
without further purification as received.
2.1. Synthesis of ligands PPA1, PPA2 and their metal complexes
2.1.1. Synthesis of PPA from first generation (PPA1)
0.65 ml (0.002 M) of DAB-dendr-4Am was reacted with excess
of 1,8-naphthalic anhydride in 50 ml ethanol. The reaction mixture
was refluxed and heated for 2 h at 80 ◦C. Afterwards the solution
was poured into 200 ml water and the resulting precipitate was fil-
tered off, washed with water and dried to a constant weight. In order
to remove the unreacted 1,8-naphthalic anhydride, the precipitate
was treated with 20 ml 5 wt.% NaOH solution. Thus the unreacted
1,8-naphthalic anhydride was dissolved and removed after filtra-
tion while the modified poly(propylene amine) remained as the
precipitate. Yield: 53.8%.
Fig. 1. Structure of first generation dendrimer PPA (PPA1).
2.1.2. Synthesis of PPA from second generation (PPA2)
formation in the central part of the dendrimer. The internal amido
groups of PAMAM can become in the reactions with the rare earth
ions (receptor) [41]. So the fluorescence properties of the novel
compounds in the presence of different metal cations show that
these dendrimer could act as fluorescent properties of this fluoresc-
ing dendrimer are based on the complexing ability of the PAMAM
core [40,42–45].
Poly(propylene amine) (PPA) dendrimers are interesting class,
as they exhibit stronger basicity and hydrophobicity in the inte-
rior of the macromolecule due to the presence of tertiary amino
groups. Each generation comprises 2n+1 tertiary amino groups
in the interior and 2n+1 − 2 peripheral functional groups, where
n is the number of generation. The photophysical properties of
poly(propylene amine) dendrimers functionalized with dansyl or
azobenzene units at the periphery have been investigated [46–52].
In this work, the study is focused on syntheses and spectroscopic
studies, thermal investigation, kinetic parameters as well as the
antibacterial screening of dendrimer from first (Fig. 1) and second
(Fig. 2) generation with their Cu2+ and Zn2+ complexes.
0.78 ml (0.001 M) of DAB-dendr-8Am was reacted with excess
of 1,8-naphthalic anhydride in 50 ml ethanol. The reaction mix-
ture was refluxed and heated for 1 h at 80 ◦C. Then the solution
was poured into 200 ml water and the resulting precipitate was fil-
tered off, washed with water and dried to a constant weight. The
unreacted 1,8-naphthalic anhydride was dissolved in 20 ml 5 wt.%
NaOH solution and removed after filtration while the modified
poly(propylene amine) remained as the precipitate. Yield: 65.4%.
2.1.3. Synthesis of metal complexes
All resulted complexes were synthesized by adding of the
appropriate metal salts (1.0 mmol; in 25 ml methyl alcohol) to hot
solution of the ligands (1.0 mmol; in 25 ml chloroform). The reaction
performed molar ratio (1:4) ligand:metal with PPA1 and (1:8) with
PPA2. The resulting solution were stirred and heated on a hot plate
at 80 ◦C for 3 h. The volume of the obtained solution was reduced
to one-half by evaporation 1 day later, the color solid washed with
ethanol and diethyl ether (50:50 v/v), finally dried under vacuum,
the synthesized complexes were recrystallized from ethanol. The
complexes were isolated as powdered material. Elemental analy-
sis CHN, IR, UV–vis, 1H NMR and TGA as well as atomic absorption
spectra confirmed the composition of metal complexes.
2.2. Analysis
Elemental analyses were performed using a PerkinElmer CHN
2400 elemental analyzer. Molar conductance measurements of the
PPA1 and PPA2 ligands and their complexes with 1.0 × 10−3 mol/l
in DMSO were carried out using Jenway 4010 conductivity meter.
1H NMR spectra recorded using Varian 200 MHz spectrometer with
DMSO as solvent, chemical shift are given in ppm relative to tetram-
ethylsilane. The UV/vis, spectra were obtained in DMSO solution
(1.0 × 10−3 M) for the ligands PPA1 and PPA2 and their four com-
plexes with a Jenway 6405 Spectrophotometer using 1 cm quartz
cell, in the range 200–600 nm. Magnetic measurements were car-
ried out on a Sherwood Scientific magnetic balance in the micro
analytical laboratory using Gouy method. Calibration: tow very
good solid calibrants are Hg[Co(CNS)4] and [Ni(en)3](S2O3). They
are easily prepared pure, do not decompose or absorb moisture
and pack well. Their susceptibilities at 20 ◦C are 16.44 × 10−6 and
11.03 × 10−6 c.g.s. units, decreasing by 0.05 × 10−6 and 0.04 × 10−6
per degree temperature raise, respectively, near room temperature.
The cobalt compound, besides having the higher susceptibility, also
packs rather densely and is suitable for calibrating low fields, while
Fig. 2. Structure of second generation dendrimer PPA (PPA2).

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M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
the nickel compound with lower susceptibility and density is suit-
able for higher field [53], here we are used Hg[Co(CNS)4] only as
calibrant.
IR spectra (4000–400 cm−1) were recorded as KBr pellets
on Bruker FT-IR Spectrophotometer. Thermogravimetric analyses
(TG/DTG) were carried out in the temperature range from 25 to
800 ◦C in a steam of nitrogen atmosphere using Shimadzu TGA 50H
thermal analysis. The experimental conditions were: platinum cru-
cible, nitrogen atmosphere with a 30 ml/min flow rate and a heating
rate 10 ◦C/min.
2.3. Microbiological investigations
Forthese investigationsthefilterpaperdiscmethodwas applied.
The investigated isolates of bacteria were seeded in tubes with
nutrient broth (NB). The seeded NB (1 cm3) was homogenized in the
tubes with 9 cm3 of melted (45 ◦C) nutrient agar (NA). The homo-
geneous suspensions were poured into Petri dishes. The discs of
filter paper (diameter 4 mm) were ranged on the cool medium.
After cooling on the formed solid medium, 2 × 10−5 dm3 of the
investigated compounds were applied using a micropipette. After
incubation for 24 h in a thermostat at 25–27 ◦C, the inhibition (ster-
ile) zone diameters (including disc) were measured and expressed
mm. An inhibition zone diameter over 7 mm indicates that the
tested compound is active against the bacteria under investigation.
The antibacterial activities of the investigated compounds were
tested against Escherichia coli, Pseudomonas aeruginosa as Gram
negative, Bacillus subtilis and Staphylococcus aureus as Gram pos-
itive. The concentration of each solution was 1.0 × 10−3 mol dm3.
Commercial DMSO was employed to dissolve the tested samples.
3. Result and discussion
PPA refluxed with 1,8-naphthalic anhydride readily gives rise
to the corresponding PPA1 and PPA2 which was easily iden-
tified by its IR, 1H NMR and elemental analysis. Complexes
were obtained upon reaction between metal(II) ions and lig-
ands at 1:4 and 1:8 molar ratio ligand: metal for PPA1 and
PPA2, respectively. The ligands PPA1 and PPA2 with reaction
with CuCl2·6H2O and ZnCl2·6H2O salts, yield complexes corre-
sponding to the general formula: [Cu2(PPA1)(H2O)4]·2Cl2·4H2O,
[Zn2(PPA1)(H2O)4]·2Cl2·8H2O, [Cu4(PPA2)(H2O)8]·4Cl2·4H2O and
[Zn4(PPA2)(H2O)8]·4Cl2·6H2O, the dendrimers PPA1 and PPA2 con-
taining more than one metal cation per ligand.
The newly synthesized ligands and their complexes are very sta-
ble at room temperature in the solid state. The ligands and their
metal complexes are generally soluble in DMF and DMSO. The color,
yield, melting point, decomposition points, elemental analyses and
molar conductance of ligands and their complexes are presented
in Table 1. The analytical data are in a good agreement with the
proposed stoichiometry of the complexes.
3.1. Infrared spectra
The most important bands in the infrared spectra of the PPA1
and PPA2 ligands and its complexes are presented in Table 2.
The position of these bands provide significant indication regard-
ing the bonding sites of the ligand molecules when interacted to
Cu(II) and Zn(II) ions. The functional groups of the ligands and
the metal complexes have been appeared by infrared spectra, as
given in Figs. 3 and 4. The infrared spectra of ligands showed bands
around 1383 cm−1 which was assigned to the stretching vibration
of the ꢁ(C–N) tertiary amine, this band not shifted in the com-
plexes. Infrared spectra of ligands show intensive absorption bands
at 1773–1769 and 1734–1729 cm−1 which can be assigned to the

M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
775
Table 2
Infrared spectral data for dendrimer ligands and their complexes (cm−1).
Compounds
v (OH) hydrated H2O
v (C–H) aromatic
vs (C O)
vas (C O)
v (C–N) tertiary
v (OH) coordinated H2O
v (M–O)
PPA1
3397(br)
3543(br)
3482(br)
3379(br)
3446(br)
3449(br)
3065(m)
3055(m)
3070(m)
3067(m)
3060(m)
3062(m)
1729(s)
1655(s)
1587(s)
1587(s)
1655(s)
1587(s)
1587(s)
1383(m)
1383(m)
1387(m)
1383(m)
1384(m)
1384(m)
–
–
[Cu2(PPA1)(H2O)4]·2Cl2·4H2O
[Zn2(PPA1)(H2O)4]·2Cl2·8H2O
PPA2
1696(vs)
1697(vs)
1734(vs)
1697(vs)
1697(vs)
824(w)
825(w)
–
825(w)
824(w)
428(w)
415(w)
–
427(w)
420(w)
[Cu4(PPA2)(H2O)8]·4Cl2·4H2O
[Zn4(PPA2)(H2O)8]·4Cl2·6H2O
Fig. 5. 1H NMR spectra of ligand PPA1.
Fig. 6. 1H NMR spectra of Cu(II) complex of PPA1 ligand.
Fig. 3. IR spectra of A = PPA1; B = Cu(II)/PPA1 and C = Zn(II)/PPA1 compounds.
Fig. 7. 1H NMR spectra of ligand PPA2.
asymmetrical and symmetrical carbonyl groups vibrations respec-
tively, of the 1,8-naphthalmide [54], this peak is affected after
complexation. This means that the carbonyl groups are participated
in the complexation. While the bands observed at approximately
824 cm−1 is assigned to coordinated water molecule [55]. The
coordination is confirmed by the presence of a new band at
409–428 cm−1 that can be assigned to ꢁ(M–O) [56]. Infrared spec-
tra indicates that the coordination take place through oxygen atom
of carbonyl group of 1,8-naphthalamide as bidentate.
3.2. 1H NMR spectra
1H NMR spectra of ligand PPA1 and Cu(II) complex (Figs. 5 and 6).
1H NMR (DMSO-d6) ␦(ppm) = 1.24(m, 12H, N–CH2–CH2), 2.18(t,
12H, CH2–N(CH2)–CH2), 4.13(t, 8H, CH2–N of naphthalamide),
7.74(m, 8H, Ar–H), 8.31(m, 16H, Ar–H).
1H NMR spectra of ligand PPA2 and Cu(II) complex (Figs. 7 and 8).
1H NMR (DMSO-d6) ␦(ppm) = 1.3(m, 26H, N–CH2CH2–CH2–N),
Fig. 8. 1H NMR spectra of Cu(II) complex of PPA2 ligand.
Fig. 4. IR spectra of A = PPA2; B = Cu(II)/PPA2 and C = Zn(II)/PPA2 compounds.

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M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
2.15(t, 36H, N–CH2), 4.14(t, 16H, CH2–N of naphthalamide), 7.70(m,
16H, Ar–H–3,8), 8.59(m, 32H, Ar–H–4,5,6,7).
that the Cl− ions are present, and that two water molecules com-
pletes the coordination sphere of the studied complexes.
Given the way the former (Figs. 5–8) believe that there is no
difference in places of the signals of 1H NMR spectra in comparison
between PPA1 and PPA2 and their Cu(II) complexes except for the
decreasing in the intensities according to electronic configuration
of the new complexes.
3.4. Electronic absorption spectra
The spectra of PPA from first and second generation in DMSO are
shown in Fig. 9. There are two detected absorption bands at around
360 and 385 nm (Table 3). Assigned to ␲–␲* and n–␲* interaligand
transition, respectively. These transition also found in the spectra
of the complexes. The position of the absorption maximum of den-
drimer appears at the same position regardless of the presence of
metal cations.
3.3. Molar conductivities of metal chelates
Conductivity measurements in non-aqueous solution have fre-
quently been used in structural studies of metal chelates within the
limits of their solubility. The molar conductivity values for two lig-
ands and all Cu(II) and Zn(II) complexes in (10−3 M) were in range of
6–224 ꢄ−1 cm2 mol−1 suggesting them to be electrolytes (Table 1).
This result was confirmed from the chemical analysis where Cl−
ions precipitate by addition AgNO2 solution. This fact elucidated
3.5. Magnetic measurements
Magnetic measurements were carried out on a Sherwood Scien-
tific magnetic balance according to the Gouy method. The magnetic
Fig. 9. Electronic spectra of the poly(propylene amine) dendrimers ligands and their metal complexes.

M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
777
Table 3
Electronic spectra of PPA1, PPA2 ligands and their complexes.
Compounds
PPA1
ꢅmax
ε (mol−1 cm−1
)
Assignment
(nm)
360
385
1997
1764
␲–␲*
n–␲*
Cu(II) complex
Zn(II) complex
PPA2
350
385
2824
1665
␲–␲*
n–␲*
355
385
2989
1687
␲–␲*
n–␲*
Scheme 1. Thermal degradation steps of Cu(II) and Zn(II) complexes of PPA1 and
PPA2 ligands.
360
385
2017
1707
␲–␲*
n–␲*
Cu(II) complex
Zn(II) complex
360
385
2249
1699
␲–␲*
n–␲*
were drawn as percentage mass loss versus temperature (TG)
curves. Typical TG and DTG curves are presented in Fig. 10, and the
temperature range and percentage mass losses of decomposition
reaction are given in Table 4, together with evolved moiety and
theoretical percentage mass losses. The overall loss of mass from TG
curves is 94.22%, 83.52%, 89.39%, 89.20, 91.51% and 91.47% for PPA1,
360
385
2507
1684
␲–␲*
n–␲*
moments of Cu(II) complexes at T = 293 K are given in Table 1. From
the data given in Table 1, the observed values of the effective mag-
netic moments ꢂeff measured for Cu(II) complexes lie between 1.90
and 1.92 B.M. is an indicative of square planner geometry.
[Cu2(PPA1)(H2O)4]·2Cl2·4H2O,
[Zn2(PPA1)(H2O)4]·2Cl2·8H2O,
PPA2, [Cu4(PPA2)(H2O)8]·4Cl2·4H2O and [Zn4(PPA2)(H2O)8]
·4Cl2·6H2O, respectively. All the complexes show three stages
of mass loss in their TG/DTG curves (Scheme 1). The analysis of
thermal curves of complexes clearly indicates that the weight
loss of first stage between 25 and 200 ◦C (DTGmax: ∼75 ◦C) cor-
responding to loss of hydrated water molecules. Because of the
low temperature the water molecules may be considered as
3.6. Thermal studies
The poly(propylene amine) dendrimers of Cu(II) and Zn(II)
complexes are stable at room temperature and can be stored for
several months without any change. Cu(II) and Zn(II) complexes of
PPA-dendrimers were studied by thermogravimetric analysis from
ambient temperature to 800 ◦C N2 atmosphere. The TG curves
crystal water. The second stage between 150 and 300 ◦C (DTGmax
:
∼200 ◦C) corresponding to loss of coordinated water molecules
and chloride ions. The decomposition was completely at >700 ◦C
for all complexes.
Fig. 10. The TG and DTG of the poly(propylene amine) dendrimers ligands and their metal complexes.

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M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
Table 4
Thermal decomposition of the poly(propylene amine) dendrimers ligands and their metal complexes.
Compounds
PPA1
Steps
Temperature range
DTG peaks
Weight loss (calc.)found %
Assignment
C48H24O8N4
C11 H32N2
5C
1st
2nd
25–400
400–610
610–
350
547
(75.60)75.21
(18.51)18.71
(5.78)6.08
[Cu2(PPA1)(H2O)4]·2Cl2·4H2O
[Zn2(PPA1)(H2O)4]·2Cl2·8H2O
1st
2nd
3rd
25–150
150–250
250–380
75
200
310
(4.96)5.05
(4.96)5.25
(23.03)23.56
4H2O
4H2O
4Cl + C11 H32N2
380–600
600–
25–200
200–500
500–665
665–
497
(50.20)50.74
(16.48)15.40
(9.43)8.97
(26.54)26.68
(53.47)52.61
(10.61)11.71
C46H24O6N4
2CuO + 7C
8H2O
1st
2nd
3rd
80
324
621
4H2O + 4Cl + C11 H32N2
C
53H28O6N4
2ZnO
PPA2
1st
25–600
600–
290
(88.93)89.17
(10.83)10.80
C116 H128 O16 N18
20C
[Cu4(PPA2)(H2O)8]·4Cl2·4H2O
1st
25–140
140–250
250–700
700–
75
200
300
(2.42)2.20
(14.37)14.66
(74.59)75.95
(7.49)7.19
4H2O
2nd
3rd
4th
8H2O + 8Cl
C136 H128 O16 N18
4Cu
[Zn4(PPA2)(H2O)8]·4Cl2·6H2O
1st
25–140
140–280
280–600
600–
75
270
310
(4.72)4.47
8H2O
2nd
3rd
4th
(14.03)14.50
(72.57)73.62
(8.53)7.41
8H2O + 8Cl
C136 H128 O16 N18
4Zn
3.6.1. Poly(propylene amine) dendrimers ligand (PPA1) and
(PPA2)
The second stage, within temperature range 150–250 ◦C (DTGmax
;
200) corresponding to loss of four coordinated water molecules
(calcd.: 4.96%, found: 5.25%). The energy of activation of this step is
11.5 kJ mol−1. Reported data on thermal analysis studies were col-
lected in nitrogen atmosphere media which, indicate that the Cu(II)
complex decompose to give Cu(II) oxide and few carbon atoms as
residue above 700 ◦C, weight loss (calcd.: 16.48%, found: 15.40%).
The poly(propylene amine) dendrimers ligands from first and
second generation PPA1 and PPA2 melts at 192 and 135 ◦C, respec-
tively, with simultaneous decomposition. The main peak was
observed at 350 and 290 ◦C for PPA1 and PPA2, respectively, from
the TG profile, it appears that the sample decomposes in one sharp
stage over the wide temperature range 25–800 ◦C. The decompo-
sition occurs with a mass loss (calcd.: 75.60%, found: 75.21%) for
PPA1 ligand and (calcd.: 75.60%, found: 75.21%) for PPA2 ligand.
The final products are carbon atoms as residue, interpretive for
no sufficiently of oxygen atoms encouraged the liberated carbon as
carbon monoxide or dioxide.
3.6.3. [Zn2(PPA1)(H2O)4]·2Cl2·8H2O
The thermal decomposition of Zn(II) complex with the general
formula [Zn2(PPA1)(H2O)4]·2Cl2·8H2O is thermally decomposed in
a successive three decomposition steps. The first stage within the
temperature range 25–200 ◦C (DTGmax; 80 ◦C) may be attributed
to the loss of eight hydrated water molecules, weight loss (calcd.:
9.43%, found: 8.97%). The activation energy of the thermal dehy-
dration of this complex is 11.8 kJ mol−1 The second step occurs
within the temperature range 200–500 ◦C (DTGmax; 324 ◦C) with
an estimated mass loss (calcd.: 26.54%, found: 26.68%) is reason-
ably accounted for the decomposition of four coordinated water
molecules, four chloride ions and organic moieties (C11 H32N2).
3.6.2. [Cu2(PPA1)(H2O)4]·2Cl2·4H2O
The TG of the [Cu2(PPA1)(H2O)4]·2Cl2·4H2O complex reveals a
mass loss in the temperature range 25–150 ◦C (DTGmax; 75) cor-
responding to loss of four hydrated water molecules, weight loss
(calcd.: 4.96%, found: 5.05%) for the first stage. The activation
energy of the thermal dehydration of this complex is 29.8 kJ mol−1
.
Table 5
Thermodynamic data of the thermal decomposition poly(propylene amine) dendrimers ligands and their metal complexes.
Complex
Stage
Method
Parameter
E (J mol−1
r
)
A (s−1
)
ꢀS (J mol−1 K−1
)
ꢀH (J mol−1
)
ꢀG (J mol−1
)
PPA1
1st
3rd
3rd
1st
3rd
3rd
CR
HM
1.86 × 105
1.56 × 1012
−17.6
−2.61
1.63 × 105
1.74 × 105
0.99164
0.99487
1.77 × 105
9.48 × 1012
1.72 × 105
1.73 × 105
Cu(II) complex
Zn(II) complex
PPA2
CR
HM
1.38 × 105
1.57 × 105
1.50 × 107
3.33 × 108
−115
1.31 × 105
1.50 × 105
2.20 × 105
2.19 × 105
0.99409
0.99880
−89.7
CR
HM
1.38 × 105
9.16 × 109
−60
−56
1.33 × 105
1.69 × 105
0.99458
0.99547
1.38 × 105
1.47 × 10
1.33 × 105
1.67 × 105
CR
HM
7.18 × 104
8.05 × 104
2.53 × 104
2.11 × 105
−166
−148
6.71 × 104
7.58 × 104
1.61 × 105
1.60 × 105
0.99905
0.99999
Cu(II) complex
Zn(II) complex
CR
HM
8.79 × 104
6.31 × 105
−139
−107
8.31 × 104
1.63 × 105
0.98935
0.98907
1.04 × 105
3.10 × 107
9.94 × 104
1.61 × 105
CR
HM
7.20 × 104
7.85 × 104
7.05 × 103
7.73 × 104
−177
−157
6.72 × 104
7.73 × 104
1.70 × 105
1.65 × 105
0.96216
0.99430

M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
779
Two zinc oxide molecules were left as residue, weight loss (calcd.:
10.61%, found: 11.74%).
75 ◦C), represents the loss of four hydrated water molecules, weight
loss (calcd.: 2.42%, found: 2.20%). The activation energy of the ther-
mal dehydration of this complex is 71.9 kJ mol−1. The second stage,
within the temperature range of 140–250 ◦C (DTGmax; 200 ◦C) rep-
resents the loss of eight coordinated water molecules and eight
chloride ions with an estimated mass loss (calcd.: 14.37%, found:
14.66%). The energy of activation of this step is 93.1 kJ mol−1. The
3.6.4. [Cu4(PPA2)(H2O)8]·4Cl2·4H2O
The Cu(II) complex of poly(propylene amine) dendrimers from
second generation gives three stages of decomposition pattern. The
first stage, within the temperature range of 25–140 ◦C (DTGmax
;
Fig. 11. Coats–Redfern (CR) of the degradation steps of the dendrimer and their complexes.

780
M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
Fig. 11. (Continued ).
third stage was hardly to detect the exact degradation of organic
moieties because of, this step is widely extending from 250 to
700 ◦C, weight loss (calcd.: 74.59%, found: 75.95%). the final decom-
position products is four atoms of copper metal, weight loss (calcd.:
8.49%, found: 7.19%).
The linearization curves of Coats–Redfern and Horowitz–
Metzger methods are shown in Fig. 11. Kinetic parameters for
the first stages, calculated by employing the Coats–Redfern and
Horowitz–Metzger equations, are summarized in Table 5. The cal-
culated values of ꢀE*, ꢀS*, ꢀH* and ꢀG* for the decomposition
steps are given in Table 5. According to the kinetic data obtained
from DTG curves, the high values of the activation energies reflect
the thermal stability of the complexes. The entropy of the activation
was found to have negative values in all of the complexes. Nega-
tive values indicate that the decomposition reactions proceed with
changes in order which may be more ordered due to the decompo-
sition of the complexes.
3.6.5. [Zn4(PPA2)(H2O)8]·4Cl2·6H2O
Thermal decomposition of d10 transition metal complex
[Zn4(PPA2)(H2O)8]·4Cl2·4H2O proceeds in three stages. These
stages are related to the decomposition of eight hydrated water
molecules in the first stage, weight loss (calcd.: 4.72%, found:
4.47%) within temperature range 25–140 ◦C (DTGmax; 75 ◦C). The
activation energy of the thermal dehydration of this complex
is 34.9 kJ mol−1
. The second stage within temperature range
3.8. Microbiological investigation
140–280 ◦C (DTGmax; 270 ◦C) corresponding to loss of eight coordi-
nated water molecules and eight chloride ions, weight loss (calcd.:
14.03%, found: 14.50%). The energy of activation of this step is
105 kJ mol−1. The third stage hardly to detect the exact degrada-
tion of organic moieties because of this step is widely extending
from 280 to 700 ◦C. The final decomposition products is four atoms
of zinc metal, weight loss (calcd.: 8.53%, found: 7.41%).
The biological activity of the poly(propylene amine) den-
drimers ligands (PPA1) and (PPA2) and their metal complexes
were tested against bacteria because bacteriums can achieve
resistance to antibiotics through biochemical and morphological
modifications. In testing the antibacterial activity of these com-
pounds, we used more than one test organism to increase the
chance of detecting antibiotic principles in tested materials. The
organisms used in the present investigations included two Gram
positive bacteria (B. subtillis and S. aureus) and two Gram neg-
ative bacteria (E. coli and P. aereuguinosa). The results of the
bactericidal screening of the synthesized compounds are recorded
in Fig. 12 and Table 6. The data obtained reflect the following
results:
3.7. Kinetic studies
Coats–Redfern [57] and Horowitz–Metzger [58] are the two
methods mentioned in the literature related to decomposition
kinetics studies; these two methods are applied in this study. From
the TG curves, the activation energy, E, pre-exponential factor, A,
entropies, ꢀS, enthalpy, ꢀH, and Gibbs free energy, ꢀG, were cal-
culated by well-known methods; where
3.8.1. Bacillus subtillis (G+)
Antibacterial activity of all ligands and their metal complexes
towards B. subtillis are detected and show moderate activity, except
ꢀH = E − RT and ꢀG = ꢀH − TꢀS.

M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
781
Fig. 12. The inhabitation zone of the poly(propylene amine) dendrimers ligands and their Cu(II) and Zn(II) complexes on some kinds of bacterial.
Fig. 14. Structure of PPA2 complex.
Fig. 13. Structure of PPA1 complex.

782
M.S. Refat et al. / Spectrochimica Acta Part A 72 (2009) 772–782
Table 6
Antibacterial activity data of the poly(propylene amine) dendrimers ligands and their metal complexes, inhibition zone (mm).
Compound
Bacillus subtili G+
Staphylococcus aureus G+
Escherichia coli G−
Pseudomonas aeruginosa G−
PPA1
8
12
10
8
14
16
–
–
–
7
13
11
7
7
8
12
13
14
–
7
7
10
12
12
Cu(II) complex
Zn(II) complex
PPA2
Cu(II) complex
Zn(II) complex
Cu/PPA2 and Zn/PPA2 show marked activity. B. subtillis was inhib-
ited by the complexes according to this order.
[20] M.G. Cloninger, Curr. Opin. Chem. Biol. 6 (742–748) (2002).
[21] J.F. Kukowska-Latallo, A.U. Bielinska, J. Johnson, R. Spindler, D.A. Tomalia, J.R.
Baker Jr., Proc. Natl. Acad. Sci. U.S.A. 93 (4897–4902) (1996).
[22] J. Dennij, E. Duncan, Rev. Mol. Biotechnol. 90 (339–347) (2002).
[23] M. El-Sayd, M. Ginski, C. Rhodes, H. Ghandehari, J. Control. Release 81 (355–365)
(2002).
[24] C.S. Braun, J.A. Vetro, D.A. Tomalia, G.S. Koe, J.G. Koe, C.R. Middaugh, J. Pharm.
Sci. 94 (423–436) (2005).
[25] A.U. Bielinska-Latallo, J.R. Baker Jr., Biochem. Biophys. Acta 1353 (180–190)
(1997).
[26] X. Qian, K. Zhu, K. Chen, Dyes Pigment 11 (1989) 13.
[27] V. Gruzinskii, A. Kukhta, G. Shakkah, J. Appl. Spectrosc. 65 (1998) 444.
[28] E. Martin, R. Weigind, A. Pardo, J. Lumin. 68 (1996) 157.
[29] Z.-F. Tao, X. Qian, Dyes Pigment 43 (1999) 139.
[30] Ad. Andricopulo, Ra. Yunes, F. Cechinel, Aw. Correa, R. Filho, Ar. Santos, R.J.
Numes, Acta Farn Bonaer 17 (1998) 219.
[31] E. Mykowska, K. Jazwanska, W. Grupa, D. Bauman, Proc. SPIE 3318 (1998)
378.
[32] I. Grabchev, I. Moneva, E. Wolarz, D. Bauman, Z. Naturforsch. 51a (1996) 1185.
[33] I. Grabchev, I. Moneva, V. Bojinov, S. Guittonneau, J. Mater. Chem. 10 (2000)
1291.
Zn/PPA2 > Cu/PPA2 > Cu/PPA1 > Zn/PPA1 > PPA1 = PPA2
3.8.2. Staphylococcus aureus (G+)
All ligands and their Cu(II) and Zn(II) complexes are detected and
show that, PPA1 ligand and their metal complexes have no effect
towards S. aureus. PPA2 and their metal complexes have moderate
activity.
3.8.3. Escherichia coli (G−)
The activity of the poly(propylene amine) dendrimers ligands
and their metal complexes are detected towards E. coli, all tested
compounds have activity (Table 6). PPA1 and their metal complexes
show weak activity but PPA2 and their metal complexes exhibit
moderate activity.
[34] A.P. De, H.Q.N. Silva, P. Gunaratne, L. Mark Lunch, G. Spence, J. Chem. Soc., Perkin
Trans. 2 (1999) 163.
[35] A.P. De Silva, Chem. Commun. 163 (1999).
[36] A.P. De Silva, H.Q.N. Gunaratne, J.-L. Habbib-Jiwan, C.P. McCoy, T.E. Rice, J.-P.
Soumillion, Angew. Chem. 34 (1995) 1728.
[37] K. Mitchel, R. Brown, D. Yuan, S.-C. Chang, R. Utecht, D. Lewis, J. Photochem.
Photobiol. A: Chem. 115 (1998) 157.
[38] B. Ramachandram, A. Samanta, Chem. Commun. 1037 (1997).
[39] I. Olmstedt, J. Phys. Chem. 83 (1979) 2581.
[40] I. Grabchev, S. Guitlonneau, J. Photochem. Photobiol. Sci. 179 (2006)
28–34.
3.8.4. Pseudomonas aereuguinosa (G−)
Range of activities for all ligand and their metal complexes
have weak activity or moderate activity except PPA1 have no effect
towards P. aereuguinosa.
The structures of Cu(II) and Zn(II) complexes with PPA1 and
PPA2 under the above interpretation can be designed as shown in
Figs. 13 and 14.
[41] Q.Q. Chen, L. Lin, H.M. Chen, S.P. Yang, L.Z. Yang, X.B. Yu, J. Photochem. Photobiol.
A Chem. 180 (2005) 69–74.
References
[42] I. Grabchev, V. Bojinov, J.M. Chovelon, Polymer 44 (2003) 4421.
[43] I. Grabchev, J.M. Chovelon, V. Bojinov, G. Ivanova, J. Tetrahedron 59 (48) (2003)
9591.
[44] I. Grabchev, J.P. Soumillion, B. Muls, G. Ivanova, J. Photochem. Photobiol. Sci. 3
(2004) 1032.
[45] I. Grabchev, J.M. Chovelon, X. Qian, New J. Chem. 27 (2003) 337.
[46] A. Dirksen, E. Zuidema, R.M. Williams, L. De Cola, C. Kauffmann, F. Vogtle, A.
Roque, F. Pina, Macromolecules 35 (2002) 2743–2747.
[47] V. Balzani, P. Ceroni, S. Gestermann, C. Kauffmann, M. Gorka, F. Vögtle, Chem-
Chem (2000) 853–854.
[1] G.R. Newkome, C.N. Moorefield, F. Vogtle, Dendrimers and Dendrons: Concept,
Synthesis, Application, VCH, Weinheim, Germany, 2001.
[2] D.N. Reinhoudt, J.F. Stoddart, R. Ungaro, Chem. Eur. J. 4 (1349) (1998).
[3] J.P. Majoral, A.M. Caminade, V. Maraval, Chem. Commun. 2929 (2002).
[4] I. Grabchev, X. Quian, V. Bojinov, W. Zhang, Polymer 43 (2002) 5731–5736.
[5] M. Fischer, Angew. Chem. Int. Ed. 34 (1999) 884.
[6] K. Unoue, Prog. Polym. Sci. 25 (2000) 453.
[7] F. Vogtle, S. Gesterman, R. Hasse, H. Schwiert, B. Windisch, Prog. Polym. Sci. 25
(2000) 987.
[48] A. Dirksen, L. De Cola, C.R. Chimie 6 (2003) 873–882.
[49] V. Balzani, F. Vögtle, C.R. Chimie 6 (2003) 867–872.
[50] F. Vögtle, S. Gestermann, C. Kauffmann, P. Ceroni, V. Vicinelli, L. De Cola, V.
Balzani, J. Am. Chem. Soc. 121 (1999) 12261.
[51] F. Vögtle, S. Gestermann, C. Kauffmann, P. Ceroni, V. Vicinelli, L. De Cola, V.
Balzani, J. Am. Chem. Soc. 122 (2000) 10398.
[52] F. Pina, M. Passaniti, V. Maestri, F. Balzani, M. Vögtle, S. Gorka, K. Lee, J. van
Heyst, H. Fakhrnabavi, ChemPhysChem 5 (2004) 473–480.
[53] A. Earnshow, Introduction to Magneto Chemistry, Academic, New York,
1968.
[54] Tz. Philippova, I. Karamancheva, I. Grabchev, Dyes Pigments 28 (1995) 91.
[55] G.G. Mohamed, Spectrochim. Acta: Part A 57 (2001) 411.
[56] M.S. Refat, I.M. El-Deen, H.K. Ibrahim, S. El-Ghool, Spectrochim. Acta: Part A 56
(2006) 1208–1220.
[8] T. Weil, U.M. Wiesler, A. Herrmann, R. Bauer, J. Hofkens, F.C. Deschryver, K.
Mullen, J. Am. Chem. Soc. 121 (1999).
[9] S. Gilat, A. Adronov, J. Frechet, Org. Chem. 64 (1999) 7474.
[10] S. Gilat, A. Adronov, J. Frechet, Angew. Chem. Int. Ed. 38 (1999) 1422.
[11] A. Adronov, J. Frechet, Angew. Chem. Commun. 1701 (2000).
[12] D.M. Jingle, D.V. Megrath, J. Am. Chem. Soc. 21 (1991) 4912.
[13] S. Fomie, E. Rivera, I. Fomina, A. Ortiz, T. Ogawa, Polymer 94 (1998) 3551.
[14] F. Vogtle, M. Gorka, R. Hesse, P. Ceroni, M. Maestri, V. Balzani, Photochem.
Photobiol. Sci. 1 (2002) 76.
[15] V. Balzani, P. Ceroni, S. Gestermann, F. Vogtle, M. Gorka, Chem. Commun. 853
(2000).
[16] V. Balzani, P. Ceroni, S. Gestermann, F. Vogtle, M. Gorka, J. Chem. Soc., Dalton
Trans. 765 (2000).
[17] J. Wang, M. Jiang, J. Am. Chem. Soc. 120 (1998) 8281.
[18] A.C. Chang, J. Gillespie, M. Tabacco, Anal. Chem. 73 (2001) 467.
[19] S. Svensol, D.A. Tonalia, Adv. Drug Deliv. Rev. 57 (2106–2129) (2005).
[57] A.W. Coats, J.P. Redfern, Nature 201 (1964) 68.
[58] H.H. Horowitz, G. Metzger, Anal. Chem. 35 (1963) 1464.