Polymer complexes. LX. Supramolecular coordination and structures of N(4-(acrylamido)-2-hydroxybenzoic acid) polymer complexes

Article abstract of DOI:10.1016/j.saa.2014.12.056

A number of novel polymer complexes of various anions of copper(II), cobalt(II), nickel(II) and uranyl(II) with N(4-(acrylamido)-2-hydroxy benzoic acid) (ABH) have been synthesized and characterized by elemental analysis, IR, ¹H NMR, magnetic susceptibility measurements, electronic spin resonance, vibrational spectra and thermal analysis. The molecular structures of the ligand are optimized theoretically and the quantum chemical parameters are calculated. Tentative structures for the polymeric metal complexes due to their potential application are also suggested. The IR data exhibit the coordination of ONO₂/OAc/SO₄ with the metal ions in the polymeric metal complex. Vibrational spectra indicate coordination of carboxylate oxygen and phenolic OH of the ligand giving a MO₄ square planar chromophore. Ligand field ESR spectra support square planar geometry around Cu(II). The thermal decomposition of the polymer complexes were discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated applying Coast-Redfern and Horowitz-Metzger methods.

Full text of DOI:10.1016/j.saa.2014.12.056

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Polymer complexes. LX. Supramolecular coordination and structures
of N(4-(acrylamido)-2-hydroxybenzoic acid) polymer complexes
b
b
b,1
M.M. Ghoneim a, A.Z. El-Sonbati b, , A.A. El-Bindary , M.A. Diab , L.S. Serag
⇑
a Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt
b Chemistry Department, Faculty of Science, Damietta University, Damietta, 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
The XRD patterns of AB and ABH monomer powder forms.
ꢀ
Polymer complexes of N(4-
(acrylamido)-2-hydroxybenzoic acid)
(ABH) were synthesized and
characterized.
ꢀ
X-ray diffraction pattern show a
mixture of polycrystalline and
amorphous structure for polymer
complexes.
(ABH)
ꢀ
ꢀ
ꢀ
Molecular structures of ABH are
optimized theoretically and quantum
parameters are calculated.
Thermodynamic parameters of the
decomposition stages are evaluated
and discussed.
We found that the activation energy
of PABH is greatly higher than its
polymer complexes.
(AB)
0
10
20
30
40
50
60
70
2θo
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 October 2014
Received in revised form 27 November 2014
Accepted 17 December 2014
Available online 27 December 2014
A number of novel polymer complexes of various anions of copper(II), cobalt(II), nickel(II) and uranyl(II)
with N(4-(acrylamido)-2-hydroxy benzoic acid) (ABH) have been synthesized and characterized by ele-
mental analysis, IR, 1H NMR, magnetic susceptibility measurements, electronic spin resonance, vibra-
tional spectra and thermal analysis. The molecular structures of the ligand are optimized theoretically
and the quantum chemical parameters are calculated. Tentative structures for the polymeric metal com-
plexes due to their potential application are also suggested. The IR data exhibit the coordination of ONO2/
OAc/SO4 with the metal ions in the polymeric metal complex. Vibrational spectra indicate coordination of
carboxylate oxygen and phenolic OH of the ligand giving a MO4 square planar chromophore. Ligand field
ESR spectra support square planar geometry around Cu(II). The thermal decomposition of the polymer
complexes were discussed in relation to structure, and the thermodynamic parameters of the decompo-
sition stages were evaluated applying Coast–Redfern and Horowitz–Metzger methods.
Keywords:
Polymer complexes
Thermogravimetric analysis
Thermodynamic parameters
Molecular structures
ESR
Quantum chemical parameters
Ó 2014 Elsevier B.V. All rights reserved.
Introduction
additional hydroxyl substitution in aromatic moieties. Extensive
experimental and theoretical investigations have focused on eluci-
2-Hydroxybenzoic acid and its derivatives could present as a
good model system for researching H-bonding and the effect of
dating the structures and normal vibrations of 2-hydroxybenzoic
acid and its derivatives [1–3]. Karabacak et al. [1,2] were investi-
gated 5-bromo-, 5-fluoro- and 5-chloro-2-hydroxybenzoic acid.
They obtained 8 stable conformers for each molecule. The effect
of the weak hydrogen bond between the dimers on geometry is
⇑
Corresponding author. Tel.: +20 1060081581; fax: +20 572403868.
E-mail address: elsonbatisch@yahoo.com (A.Z. El-Sonbati).
1
Abstracted from her M.Sc. Thesis.
http://dx.doi.org/10.1016/j.saa.2014.12.056
1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

112
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
investigated by comparison of the isolated-dimer and solid-state
calculation by Takahashi et al. [3].
(25 ml), and (0.1 w/v%) AIBN as an initiator were used. The result-
ing mixture was heated at reflux for 8 h. The hot solution was pre-
cipitated by addition to a large excess of distilled water containing
dilute HCl to remove the metal salts that were incorporated into
the polymer complexes. The polymer complexes (1–7, see Table 1)
were filtered, washed with water, and dried in a vacuum oven at
40 °C for several days.
2-Hydroxybenzoic acid is widely used as plant growth regula-
tors, as a preservative in food products, and in organic synthesis,
antiseptic and anti-fungal agents. It has been shown to regulate a
large variety of physiological processes in plants [4,5]. The struc-
tural features affect on the physico-chemical properties and on
the bioactivity of these compounds. They have recently become
attractive to experimentalists as well as theoreticians since their
structures are of some biological significance particularly in pheno-
lic anti-oxidants, medicine and enzyme chemistry [6–9].
Analysis and physical measurements
Microanalyses of carbon, hydrogen and nitrogen contents were
performed on Automatic Analyzer CHNS Vario ELIII, Germany. The
1H NMR spectra were carried out using Bruker WP 300 MHz using
DMSO-d6 as a solvent containing TMS as the internal standard. FT-
IR spectra (KBr discs, 4000–400 cmꢁ1) were performed using Jasco-
4100 spectrophotometer. Ultraviolet–Visible (UV–Vis) spectra of
the compounds were recorded in DMF solution using a Unicom
SP 8800 spectrophotometer. Thermal properties were investigated
using Simultaneous Thermal Analyzer (TGA) STA 6000 with a scan
rate 10 °C/min in air atmosphere from ambient temperatures to
Elvira and San Román [10] were synthesized the methacryla-
mide derivatives of 2-hydroxy-4-N-methacrylamidobenzoic acid
(4-HMA)
and
2-hydroxy-5-N-methacrylamidobenzoic
acid
(5-HMA). The monomers obtained present phenolic–OH and car-
boxylic functional groups in different positions of the side aromatic
ring with respect to the methacrylamide group. The stereochemi-
cal configuration of polymers was analyzed for poly(4-HMA) and
poly(5-HMA), the difference being explained in terms of the inter-
and intramolecular interactions of the polar –OH and –COOH side
groups through hydrogen bonding.
800 °C. X-ray diffraction patterns of the powder form, is recorded
0
The present study describes the mechanism coordination behav-
ior of novel monomer ABH with Cu(II), Co(II), Ni(II) and UO2(II) ions.
The structure of the studied polymer complexes is elucidated using
elementalanalyses, IR, 1H NMR, solidreflectance, magnetic moment,
ESR, molar conductance and thermal analyses measurements. The
thermaldecomposition and thermodynamic parameters ofthe poly-
mer complexes were evaluated and discussed.
on X-ray diffractometer with CuKa-radiation (k = 1.540598 ÅA) in
the range of diffraction angle (2h° = 4–70°). The applied voltage
and the tube current are 40 kV and 30 mA, respectively. The molec-
ular structures of the investigated compounds were optimized by
HF method with 3-21G basis set. The molecules were built with
the Perkin Elmer ChemBio Draw and optimized using Perkin Elmer
ChemBio3D software [15,16]. ESR measurements of powdered
samples were recorded at room temperature using an X-band
spectrometer utilizing a 100 kHz magnetic field modulation with
diphenylpicrylhydrazyl (DPPH) as a reference material. The con-
ductance measurement was achieved using Sargent Welch scien-
tific Co., Skokie, IL, USA.
Experimental
Materials
All chemicals used were of the analytical reagent grade (AR), and
of highest purity available. The chemicals used included acryloyl
chloride (AC) (Aldrich Chemical Co., Inc.) was used without further
purification. It was stored below ꢁ18 °C in a tightly glass-stoppered
flask. 2,20-Azobisisobutyronitrile (AIBN) (Aldrich Chemical Co., Inc.)
was used as initiator for all polymerizations. It was purified by dis-
solving it in hot ethanol and filtering [11]. The solution was left to
cool. The pure material was being collected by filtration and then
dried. Metals of CuCl2 and Cu(NO3)2ꢂ3H2O (Sigma) and Cu(OAc)2ꢂH2-
O, Co(OAc)2ꢂ4H2O, Ni(OAc)2ꢂ4H2O and UO2(NO3)2ꢂ5H2O (BDH).
Organic solvents were spectroscopic pure from BDH Aldrich Chem-
ical Co., Inc. included ethanol, benzene and dimethyl formamide.
Results and discussion
4-Acrylamido-2-hydroxybenzoic acid (ABH) monomer was pre-
pared by amidation reaction of acryloyl chloride with 4-amino-2-
hydroxybenzoic acid in benzene solvent with continuous stirring
at 0 °C [13]. ABH monomer was polymerized by free radical poly-
merization by using 2,20-azoisobutyronitrile (AIBN) as initiator.
All the polychelates are dark color solids. They are insoluble in
common organic solvents. ABH-metal ion polymer complexes were
prepared by the reaction of equimolar amounts of ABH monomer
and metal salts using (0.1 w/v%) AIBN as initiator and DMF as sol-
vent. The elemental analyses of all these polychelates indicate 1:1
and 1:2 (metal:ligand) stoichiometry (Table 1).
Preparation of monomer and polymer
The amidation of 4-amino-2-hydroxybenzoic acid was per-
formed with acryloyl chloride at 0 °C as described previously
[12–14]. The crude product was crystallized from ethanol forming
a gray powder of ABH monomer (Scheme 1). The yield is 75.23%,
m.p. 170 °C. Analytical Calc. for C, 57.97; H, 4.35; N, 6.76%. Found:
C, 57.77; H, 4.32; N, 6.66%.
Poly(N-4-acrylamido-2-hydroxybenzoic acid) (PABH) homopol-
ymer was prepared by free radical initiation of ABH using (0.1 w/v)
% AIBN as initiator and DMF as solvent and reflux for 6 h
(Scheme 1). The polymer product was precipitated by pouring in
distilled water and dried in a vacuum oven for several days at
40 °C.
Theoretical study
Calculated energies and energy difference for all conformers of
the 4-acrylamido-2-hydroxybenzoic acid (ABH), determined by HF
method with 3-21G basis set. The geometrical structure scheme of
all conformers is shown in Fig. 1. Stabilization energy of each con-
former, the highest occupied molecular orbital energy (EHOMO), the
lowest unoccupied molecular orbital energy (ELUMO) and the
energy gap between HOMO and LUMO are summarized in Table 2.
The lowest value of these stabilization energies showed that a sta-
ble conformer (C1). Intramolecular hydrogen bonds can be respon-
sible for the geometry and the stability of
a predominant
conformation; the formation of hydrogen bonding between a
hydroxyl group and COOH cause the structure of the conformer
C1 to be the most stable conformer.
Preparation of polymer complexes
In a typical preparation, a solution of ABH (0.01 mol) in dimeth-
ylformamide (DMF; 20 ml), the metal salts (0.01 mol) in DMF
Comparison study is established between stable conformer of
4-amino-2-hydroxybenzoic acid (AB), ABH (C1) and ABH dimer

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
113
H
C
H
C
H
C
H
H
H
NH2
H
H
H
H
C
C
C
C
C
C
C
H
H
H
H
+
H
+
C
C
O
N
O
N
O
N
Dry benzene
0 - 5 oC
OH
Cl
C
O
HO
O
+
O
H
O
O
C
C
+
C
H
H
O-
O
H
O-
HO
O
HO
I
III
II
Different forms of ABH
n
H
C
O
N
R
C
R
C
DMF
reflux
O
OH
O
H
H
H
C
O
HO
O
O
O
O-
PABH
O
H
O
O
H
H
O
H
R
C
C
R
CH2
C
R=
n
O
CONH
H
O
IV
Scheme 1. The formation mechanism of ABH and PABH and intra- and inter-molecular hydrogen bond.
Table 1
Elemental analysis (C, H, N and M)a of polymer complexes (1–7) (for molecular structures see Fig. 5).
Compoundb
leff.
B.M.
dia.
Color
Experimental (calc.) (%)
C
H
N
M
[[UO2(AB)2]ꢂ2H2O]n
Black
33.32
2.12
3.67
32.89
1
(33.43)
48.00
(2.23)
3.65
(3.9)
5.43
(33.15)
12.55
[[Cu(AB)2]ꢂ5/4H2O]n
1.82
1.88
1.86
1.84
4.61
dia.
Deep brown
Brown
2
(48.19)
32.88
(3.72)
2.66
(5.62)
7.54
(12.76)
17.23
3
[[Cu(AB)(ONO2)(OH2)]ꢂ 4H2O]n
(33.06)
40.43
(2.76)
2.88
(7.71)
3.77
(17.5)
17.66
3
[[Cu(AB)(OAc)].½H2O]n
4
Deep brown
Brown
(40.51)
31.46
(3.09)
2.28
(3.94)
3.55
(17.87)
16.47
3
[[Cu(ABH)(O2SO2)]ꢂ 4H2O]n
(31.58)
37.87
(2.37)
3.33
(3.68)
3.43
(16.72)
15.33
5
[[Co(AB)(OAc)(OH2)]ꢂ2H2O]n
Brown
6
(38.1)
38.00
(3.44)
2.77
(3.7)
3.54
(15.59)
15.32
[[Ni(AB)(OAc)]ꢂ3H2O]n
Brown
7
(38.13)
(2.91)
(3.71)
(15.54)
a
The excellent agreement between calculated and experimental data supports the assignment suggested in the present work.
L is the anion of ABH as given in Scheme 1, insoluble in water, but partially soluble in ethanol and completely soluble in DMF.
b

114
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
ELUMO ꢁ EHOMO
structures (Fig. 2). We found that, AB has higher stabilization
energy than ABH and its dimer structure, so AB is less stable than
ABH and ABH dimer (Table 3). Intermolecular hydrogen bond
which is formed in ABH dimer showed lower stabilization energy
than monomeric form (ABH). So, ABH dimer is more stable com-
pared to ABH.
Molecular structure (HOMO & LUMO) is shown in Fig. 3 for all
conformers. Also HOMO & LUMO of AB, ABH (C1) and its dimer
structure are presented in Fig. 4. The HOMO–LUMO energy gap,
g
¼
¼
ð3Þ
2
1
g
r
ð4Þ
ð5Þ
ð6Þ
Pi ¼ ꢁ
v
1
S ¼
D
E, which is an important stability index, is applied to develop the-
oretical models for explaining the structure and conformation bar-
riers in many molecular systems. The smaller is the value of E, the
2g
Pi2
D
x
¼
ð7Þ
ð8Þ
more is the reactivity of the compound has [17–19]. The calculated
quantum chemical parameters are given for all conformers in
Table 2 and for AB, ABH and ABH dimer in Table 3, respectively.
2
g
Pi
g
Additional parameters such as separation energies,
electronegativities, , chemical potentials, Pi, absolute hardness,
, absolute softness, , global electrophilicity, [20,21], global
softness, S, and additional electronic charge, Nmax, have been cal-
culated according to the following equations [22]:
D
E, absolute
D
Nmax ¼ ꢁ
v
g
r
x
The predicted bond lengths and bond angles for most stable
conformer AB, ABH (C1) and ABH dimer are tabulated in Tables 4
and 5.
D
In the ring part, the CꢁC bond lengths of the benzene ring for AB
are observed in the range 1.34–1.353 Å. The C@O bond lengths in
the carboxylic acid group conform to the average values are tabu-
lated for an aromatic carboxylic acid in which C@O is 1.212 Å and
CꢁO is 1.358 Å. The NH2 showed identical value of N–H bond
lengths (1.049 Å). ABH showed nearly values to AB bond lengths,
D
E ¼ ELUMO ꢁ EHOMO
ð1Þ
ð2Þ
ꢁðEHOMO þ ELUMO
Þ
v
¼
2
C1
C2
C3
C4
C5
C6
C7
C8
Fig. 1. Molecular structure with atomic numbering for all conformers of ABH.

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
115
Table 2
Stabilization energy, HOMO, LUMO and other additional parameters of all ABH Conformers.
Compound
EHOMO (a.u.)
ELUMO (a.u.)
D
E (a.u.)
v
(a.u.)
g
(a.u.)
r
(a.u.)ꢁ1
Pi (a.u.)
S (a.u.)ꢁ1
x
(a.u.)
DNmax
1
2
3
4
5
6
7
8
ꢁ0.3481
ꢁ0.4158
ꢁ0.4184
ꢁ0.4174
ꢁ0.4176
ꢁ0.4180
ꢁ0.4193
ꢁ0.4167
ꢁ0.1701
ꢁ0.1676
ꢁ0.1694
ꢁ0.1710
ꢁ0.1730
ꢁ0.1711
ꢁ0.1698
ꢁ0.1710
0.1780
0.2482
0.2490
0.2464
0.2446
0.2469
0.2494
0.2457
0.2590
0.2917
0.2939
0.2942
0.2953
0.2945
0.2945
0.2938
0.0890
0.1241
0.1245
0.1232
0.1223
0.12345
0.12474
0.1228
11.223
8.0580
8.0305
8.1158
8.1766
8.1001
8.0163
8.1400
ꢁ0.2590
ꢁ0.2917
ꢁ0.2939
ꢁ0.2942
ꢁ0.2953
ꢁ0.2945
ꢁ0.294
5.6117
4.0290
4.0152
4.0579
4.0883
4.0500
4.0081
4.0700
0.3755
0.3430
0.3469
0.3513
0.3565
0.3514
0.3477
0.3515
2.903
2.351
2.360
2.388
2.414
2.386
2.361
2.392
ꢁ0.2938
AB
ABH
Dimer
Fig. 2. Molecular structure with atomic numbering for AB, ABH and ABH dimer.
Table 3
Stabilization energy, HOMO, LUMO and other additional parameters of AB, ABH and its dimer.
Compound
EHOMO (a.u.)
ELUMO (a.u.)
D
E (a.u.)
v
(a.u.)
g
(a.u.)
r
(a.u.)ꢁ1
Pi (a.u.)
S (a.u.)ꢁ1
x
(a.u.)
DNmax
AB
ABH
Dimer
ꢁ0.425
ꢁ0.372
ꢁ0.347
ꢁ0.095
ꢁ0.179
ꢁ0.173
0.330
0.194
0.174
0.260
0.276
0.260
0.165
0.097
0.086
6.052
10.337
11.510
ꢁ0.260
ꢁ0.276
ꢁ0.260
3.0259
5.048
5.7554
0.2048
0.393
0.3907
1.574
2.849
2.999
while showed a remarkable change in NH bond length of ABH due
to bonding with acryloyl molecule. In ABH, N–H bond length is
1.01 and N–C bond length is 1.365.
the formation of hydrogen bonding between two molecules via a
hydroxyl group and –COOH cause the structure of the dimer to
be the most stable conformer. The intermolecular hydrogen bonds
are almost linear (the O–H. . .O angle equals 179.4°) and their
length is 2.063 Å. The intramolecular hydrogen bonds between
the hydroxyl groups and the oxygen atoms of the carbonyl groups
are strongly bent (the O–H. . .O angle equals 164.7°) and the O. . .O
distance is 2.056 Å [23].
Bond angle C5ꢁC4ꢁC7 is smaller than C3ꢁC4ꢁC7 because of
interaction between the carboxyl acid (COOH) and hydroxyl (OH)
group of AB and ABH (Fig. 2). These results are in agreement with
literatures [1–3]. The torsional angles of AB (C5ꢁC4ꢁC7ꢁO9 and
C3ꢁC4ꢁC7ꢁO8 are 179.992° and 179.997°, respectively) and
ABH (C5ꢁC4ꢁC7ꢁO9 and C3ꢁC4ꢁC7ꢁO8 are 178.8° and 179.3°,
respectively). The tilt angles are calculated 180°. The dihedral
angles are nearly the same among the all conformers.
Composition and structure of polymer complexes
The geometric structure of ABH dimer is also calculated (Fig. 2).
Stabilization energy lowest value of dimer showed higher stability
than ABH. Intermolecular hydrogen bonds can be responsible for
the geometry and the stability of a predominant conformation;
The solid polymer complexes of Cu(II) and UO2(II) ions with
ABH monomer are subjected to elemental analyses, IR, 1H NMR,
solid reflectance, magnetic studies, molar conductance and ther-

116
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
mal analyses to identify their tentative formulae in a trial to eluci-
date their molecular structure.
The data of elemental analysis as given in Table 1 denote that
three types of complexes were formed. For the first case the ligand
behave as a monobasic and not contains anion (complex without
chloride anions) (1M:2L molar ratio, Fig. 5(A)).
ΔE = 0.2446 a.u.
C5
UO2ðNO3Þ2 ꢂ 5H2O þ ABH ! ½½UO2ðABÞ2ꢃ ꢂ 2H2Oꢃn
Conformers
LUMO
HOMO
ΔE = 0.1780 a.u.
C1
ΔE = 0.2469 a.u.
C6
ΔE = 0.2482 a.u.
C2
ΔE = 0.2494 a.u.
C7
ΔE = 0.2490 a.u.
C3
C8
ΔE = 0.2457 a.u.
ΔE = 0.2464 a.u.
C4
Fig. 3 (continued)
5
CuCl2 þ ABH ! ½½CuðABÞ2ꢃ ꢂ H2Oꢃ
4
n
For the second case the ligand behave as a monobasic and con-
tains one anion (complexes with half equivalent anions) (1M:1L
molar ratio, as shown in Fig. 5(B and C)).
Fig. 3. Molecular structure HOMO and LUMO for ABH conformers.

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
117
Compounds
AB
LUMO
HOMO
ΔE = 0.330 a.u.
ABH
ΔE = 0.178 a.u.
Dimer
LUMO
ΔE = 0.174 a.u.
HOMO
Fig. 4. Molecular structures HOMO and LUMO for AB, ABH (C1) and ABH dimer.
ꢀ
ꢁ
3
4
complexes and there is no counter ion present outside the coordi-
nation sphere of polymer complexes [24].
CuðNO3Þ2 ꢂ 3H2O þ ABH ! ½CuðABÞðONO2ÞðOH2Þꢃ ꢂ H2O
n
The number of water molecules varies according to the nature
of the metals. Thus the results of elemental analysis clarify, that
three types of bonding are formed between the M2+ ions and the
ligand under study, those with covalent, ionic and partially ionic
and covalent bonds.
ꢀ
ꢁ
1
2
CuðOAcÞ2 ꢂ H2O þ ABH ! ½CuðABÞðOAcÞꢃ ꢂ H2O
n
CoðOAcÞ2 ꢂ 4H2O þ ABH ! ½½CuðABÞðOAcÞðOH2Þꢃ ꢂ 2H2Oꢃn
NiðOAcÞ2 ꢂ 4H2O þ ABH ! ½½NiðABÞðOAcÞꢃ ꢂ 3H2Oꢃn
For the third case the ligand behave as a neutral and contains
anion (complex with equivalent anion) (1M:1L molar ratio, Fig. 5D)
All the polymer complexes have high melting point, denoting a
strong bonding between the ligand and metal ions. It is interesting
to point out that, the data of elemental analysis are in satisfactory
agreement with the expected formula which gives support for the
suggested composition.
ꢀ
ꢁ
Infrared spectra
3
4
CuSO4 ꢂ 5H2O þ ABH ! ½CuðABHÞðO2SO2Þꢃ ꢂ H2O
n
The IR spectra of ABH ligand and all these polychelate resemble
each other in general appearance. However there is a noticeable
difference in certain vibrational frequencies.
Where AB = deprotonated ABH.
The molar conductance values for the polymer complexes (1–7)
(10ꢁ3 M) are determined in DMF and these values are found to be a
low value which indicates the non-ionic nature of these polymer
Examination of IR spectrum of the ABH shows a medium broad
band around 3400–3100 cmꢁ1 which may be assigned to OH of

118
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
Table 4
Bond lengths for AB, ABH and its dimer.
Bond lengths (Å)
AB
ABH
Intermolecular hydrogen bond (ABH Dimer)
O(9)–H(10)
C(5)–H(18)
C(1)–H(16)
C(2)–H(17)
O(11)–H(12)
C(4)–O(11)
C(7)–O(9)
C(7)–O(8)
C(3)–C(7)
C(6)–C(1)
C(5)–C(6)
C(4)–C(5)
C(3)–C(4)
0.971
1.104
1.103
1.103
0.971
1.363
1.358
1.212
1.368
1.339
1.34
1.346
1.353
1.348
1.341
1.049
1.049
1.268
O(9)–H(24)
C(6)–H(23)
C(3)–H(22)
C(2)–H(21)
O(10)–H(11)
C(5)–O(10)
C(7)–O(9)
C(7)–O(8)
C(4)–C(7)
C(6)–C(1)
C(5)–C(6)
C(4)–C(5)
C(3)–C(4)
C(2)–C(3)
C(1)–C(2)
N(12)–H(17)
N(12)–C(13)
N(12)–C(1)
C(13)–C(15)
C(13)–O(14)
C(15)–C(16)
C(16)–H(20)
C(16)–H(19)
C(15)–H(18)
0.971
1.098
1.102
1.104
1.0
1.379
1.349
1.229
1.366
1.346
1.345
1.35
1.339
1.342
1.348
1.01
1.365
1.35
O(9)–H(10)
H(10)–O(26)
O(27)–H(28)
H(28)–O(8)
O(11)–H(12)
H(12)–O(8)
O(29)–H(39)
O(26)–H(39)
1.010
1.075
0.991
1.072
0.995
1.061
1.003
1.073
C(2)–C(3)
C(1)–C(2)
N(13)–H(15)
N(13)–H(14)
C(6)–N(13)
1.36
1.206
1.342
1.1
1.102
1.105
Table 5
Bond angles for AB, ABH and its dimer.
Bond angles (°)
AB
ABH
Intermolecular hydrogen bond (ABH Dimer)
H(15)–N(13)–C(6)
H(14)–N(13)–C(6)
H(15)–N(13)–H(14)
O(9)–C(7)–O(8)
O(9)–C(7)–C(3)
O(8)–C(7)–C(3)
C(4)–C(3)–C(7)
C(2)–C(3)–C(7)
C(1)–C(6)–N(13)
C(5)–C(6)–N(13)
120.281
C(1)–N(12)–H(17)
C(1)–N(12)–C(13)
H(17)–N(12)–C(13)
O(9)–C(7)–O(8)
O(9)–C(7)–C(4)
O(8)–C(7)–C(4)
109.793
133.388
116.819
119.333
125.455
115.212
118.337
123.144
126.721
115.026
122.966
124.552
111.542
123.905
O(26)–H(10)–O(9)
O(8)–H(28)–O(27)
O(11)–H(12)–O(8)
O(29)–H(39)–O(26)
176.730
120.161
119.558
113.465
121.977
124.558
118.119
122.862
120.422
120.593
179.427
164.782
164.113
C(7)–C(4)–C(5)
C(7)–C(4)–C(3)
N(12)–C(1)–C(6)
N(12)–C(1)–C(2)
H(20)–C(16)–C(15)
C(15)–C(13)–O(14)
C(15)–C(13)–N(12)
O(14)–C(13)–N(12)
Torsional angles (°)
C(2)–C(3)–C(7)–O(8)
C(4)–C(3)–C(7)–O(9)
179.992
179.997
C(5)–C(4)–C(7)–O(9)
C(3)–C(4)–C(7)–O(8)
178.807
179.382
phenolic, carboxylic O–H and amide –N–H stretching vibration
[25]. This observed region may be due to mixing of intramolecular
and intermolecular hydrogen bonding due to N–H and O–H groups
(Scheme 1(I and IV)). Well resolved sharp band around 3300 cmꢁ1
observed in the spectra of all polymer metal complexes indicates
the presence of an N–H/O–H group indicative of participation of
carboxylic OH group in metal bonding. The spectrum of ligand
ABH shows strong bands at 1690 and 1660 cmꢁ1 which may be
attributed to carbonyl stretching frequencies due to aromatic car-
boxylic and amide groups, respectively.
All the polymer metal complexes show the absence of a band
at 1690 cmꢁ1 and shift in the band of the amide around
1660 cmꢁ1 to around 1650–30 cmꢁ1. It is quite possible that the
band due to carboxylic carbonyl group would have been involved
in coordination with metal ion while amide carbonyl group may
not be participating in direct metal bonding. However, all the
polymer metal complexes reveal the presence of two bands
around 1600 and 1460 cmꢁ1. This may be due to the carboxylate
ion [26]. It is well established that the band around 1600 cmꢁ1 is
due to symmetric stretching and that of 1460 cmꢁ1 is due to anti-
symmetric stretching vibrations of the carboxylate ion [27]. The
frequency difference [
D
t
=
t
as(COOꢁ) ꢁ
t
s(COOꢁ)] can be used
as an indication of the binding mode of the carboxylate [27]. If
Dt
is greater than 200 cmꢁ1, the group is probably bound in a
monodentate way, as was observed for the polymeric complexes
reported herein.
A strong band at 1280 cmꢁ1 in the spectrum of ligand may be
due to hydrogen bonded O–H in plane bonding vibration. All the
polymer metal complexes show this band shifted to 1250 cmꢁ1
which may be due to –O–M suggesting coordination through the
carboxylic oxygen [28]. These two bands are either slightly shifted
to lower frequencies or remained decreased markedly in intensity.
This indicates that the carboxylate group participated in complex
formation with the metal ions [28].

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
119
X
O
O
O
O
O
.nH2O
M
.nH2O
M
OH2
O
n
n
M= UO2(II) (1), n=2
M=Cu(II) (2), n=5/4
M= Cu(II) (3), X= ONO2, n=¾;
M= Co(II) (6), X= OAc, n=2
(B)
(A)
O
O
O
O
O
O
O
Cu
S
H3C
¾ H2O
n H2O
M
O
O
O
n
n
M= Cu(II) (4), n=½;
M= Ni(II) (7), n=3
(5)
(D)
(C)
Fig. 5. Structure of polymer complexes.
Participation of the phenolic and carboxylic OH groups is also
confirmed by the appearance of new bands in the complexes is
usual range (1.60–1.92 Å) observed for dioxouranium(IV) com-
plexes [36].
the 465–445 cmꢁ1 regions which is consistent with the
t(M–O)
The existence of water of hydration and/or water of coordina-
tion in the spectra of all the polymer metal complexes render it dif-
ficult to get conclusion from the phenolic group of the ligand,
which would be overlapped by those of the water molecules. The
participation of the phenolic group is further confirmed by clarify-
stretching vibration [29] as suggested by Soliman and Mohamed
[25]. In the IR spectrum of the polymer complex containing nitrate
as the gegenion, the band observed at 275 cmꢁ1 can be assigned to
t
(Cu–ONO2), consistent with the bands at 255 cmꢁ1 reported ear-
lier for Cu–ONO2 in metal complex [30]. Moreover, in the nitrato
polymer complex of ABH, two strong bands at 1285 and
1407 cmꢁ1 corresponding to t1 and t4 modes of nitrato groups
with a separation of 122 cmꢁ1 indicate the presence of a terminally
bonded monodentate nitrate group [31]. The IR spectrum of poly-
mer complex (5) contains strong bands at 1000, 1115, 1206 cmꢁ1
ing the effect of chelation on the
t
(C–O) stretching vibration. The
shift of the
t
(C–O) of phenolic group, from 1280 cmꢁ1 in the free
ligand to 1270–1255 cmꢁ1 in the polymer metal complexes forma-
tion [10,34]. Also the participation of the OH group is apparent
from the shift in position of the d(OH) in-plane bending from
1395 cmꢁ1 in the free ligand to 1390–1375 cmꢁ1 in the polymer
metal complexes [38].
due to t t2, and these
3, 955 cmꢁ1 due to t1 and 465 cmꢁ1 due to
can be assigned to a bridging bidentate sulfato group [31]. In the
The presence of water molecule in the polymer metal com-
plexes are assisted by the appearance of a broad band within the
acetate polymer complex (6) the peaks are observed at
1561 cmꢁ1
t
(C@O) and 1388 cmꢁ1
t
(C–O); the difference in the
range 3450–3300 cmꢁ1, which is attributed to
t(OH2) of the water
main two peaks, i.e. 173 cmꢁ1 suggests that the acetate ions are
coordinated to the metal ion in monodentate fashion [31,32].
In the polymer complexes (4 & 7), the bands which are observed
molecules associated with the polymer complex formation. Also a
bending vibration of the water molecules, d(OH2), is found in the
range 960–915 cmꢁ1. The other bending vibration of the water
molecules, d(OH2), is usually around 1600 cmꢁ1 which always
interferes with the skeleton vibration of the benzene ring (C@C
vibration).
near 1530 and 1435 cmꢁ1 attributed to
t
as(OCO) and
ts(OCO) of
the acetate group, respectively, indicate asymmetric bidentate
coordination of this group
100 cmꢁ1) [33].
(
D
t
(OCO) =
t
as(OCO) ꢁ
ts(OCO) <
The IR spectrum of the uranium polymer complex (1) exhibits
1H NMR spectra
two bands at 942 and 822 cmꢁ1 which are assignable to
t
as(O@U@O) and
tion indicates that the linearity of the O@U@O group is maintained
in the complex [34]. The force constant (f) for the as(O@U@O)
t
s(O@U@O) modes, respectively. This observa-
The 1H NMR spectrum of PABH homopolymer was recorded in
DMSO-d6 solution using TMS as internal standard, includes six res-
onances at 10.80, 7.57, 7.28, 3.20, 2.53 and 2.10 ppm relative to
TMS which may be assigned to the COOH, CONH, aromatic protons,
OH phenolic, vinylic –CH– and –CH2 protons, respectively. There is
a weak peak at 3.25 ppm due to the water proton. On addition of
D2O the intensities of NH, OH and COOH protons significantly
decreases. The peaks at (10.80, 3.20 and 7.57 ppm), which are
due to the exchangeable hydrogen-bonded carboxyl/hydroxyl/
amine (COOH/OH/NH) proton, disappear upon exchange with
t
mode was calculated for polymer complex (1) by the following
the method of McGlynn et al. [35]. It was found to be
7.34 mdyne/Å, and agrees well with the force constant values of
similar dioxouranium(VI) complexes [36]. From this work, the
U–O bond distance RU–O was calculated by using Jone’s
equation [37], R = 1.08fꢁ1/3 + 1.17, where f is the force constant
for the tas(O@U@O). It was found to be 1.72 Å, and this is in the

120
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
D2O and can be associated with the COOH/OH/NH protons involved
in intramolecular hydrogen bonding indicating the involvement of
the COOH group in chelation through displacement of the COOH
proton.
In the 1H NMR spectrum of polymer complex (1), the signal for
the proton of COOH group disappeared, suggesting the participa-
tion of COOH proton to the metal center in the formation of
COO-M and the proton of phenolic OH group were shifted towards
down field, due to the coordination of phenolic oxygen with metal
and a significant shifting in all the peaks was observed which con-
firm the formation of polymer metal complex. The peak of aro-
matic protons became broad due to the intramolecular
(ABH)
(AB)
interaction towards the metal ion and variation in the
density around the protons.
p-electron
X-ray diffraction
The X-ray diffraction patterns (XRD) of AB, ABH monomer and
its complexes in powder forms are shown in Figs. 6 and 7, respec-
tively. The XRD patterns of the AB and ABH monomer powder
forms are polycrystalline with different structure and various
degree of crystallinity (Fig. 6). The XRD pattern for polymer com-
plexes (1 & 2) indicates a mixture of polycrystals and amorphous
structure (Fig. 7 (1 & 2)). While the XRD patterns for all other cop-
per polymer complexes (Fig. 7 (3–5)) are completely amorphous.
The average crystallite size (D) can be determined using by Scher-
rer equation [39–41]:
0
10
20
30
40
50
60
70
2θo
Fig. 6. The XRD patterns of AB and ABH monomer powder forms.
(5)
(4)
(3)
0:9k
D ¼
ð9Þ
b1=2 cos h
(2)
The equation uses the reference peak width at angle (h), where k
is wavelength of X-ray radiation (1.541874 Å) and b1/2 is the width
at half maximum of the reference diffraction peak measured in
radians. The dislocation density, d, is the number of dislocation
lines per unit area of the crystal. The value of d is related to the
average particle diameter (D) by the relation [40]:
(1)
1
d ¼
ð10Þ
D2
0
10
20
30
40
50
60
70
The values of D are 418 and 270 nm for AB and ABH monomer,
respectively. The values of d are 5.72 ꢄ 10ꢁ6 and 1.37 ꢄ 10ꢁ5 for AB
and ABH monomer, respectively.
2θo
Fig. 7. The XRD patterns of polymer complexes powder forms (1–5).
TGA analysis
decomposition of the rest of the monomer leaving metal oxides
residue (Table 6).
The thermal behavior of PABH homopolymer and its polymer
complexes (1–7) were investigated using thermogravimetric anal-
ysis (TGA). TGA curves of all compounds are shown in Fig. 8.
Weight loss percentage in each stage of PABH homopolymer and
its polymer complexes (1–7) is presented in Table 6. It can be seen
clearly that the mass losses obtained from the TG curves and that
calculated for the corresponding molecule or molecules as well as
the final decomposition product are in good agreement for all of
the decomposition steps. PABH homopolymer shows two decom-
position steps [42,43], the first stage occur in the temperature
range 170–185 °C is attributed to decarboxylation mechanism
(Found 29.95% and calc. 28.07%). The second stage in the tempera-
ture range 185–255 °C corresponding to combustion of a part of
the monomer (C6H4N) (Found 43.73%; calc. 42.99%) and at higher
temperature 300–605 °C, loss of acrylaldehyde molecule (C3H3O)
(Found 26.32%; calc. 26.57%) [42]. All polymer complexes showed
TG curves in the temperature range ꢅ30 to 120 °C loss of outer
water molecules. The second stage is related to loss of CO2 gas or
coordinated water molecule. The third stage is attributed to loss
of a part of the monomer. The final weight losses are due to the
The TGA is used for the determination of rates of degradation of
PABH homopolymer and its polymer complexes. The rate constant
of the thermal decomposition was plotted according to the Arrhe-
nius relationship [44,45]:
ln Kꢆ ¼ ln Å ꢁ Eꢆ=RT
where K⁄ is the rate constant of the thermal degradation, Å is a pre
exponential constant, E⁄ the thermal activation energies of decom-
position, R is a gas constant (= 8.314 J Kꢁ1 molꢁ1) and T is the abso-
lute temperature. The activation energies of decomposition (E⁄) are
calculated from the slope of the straight line obtained from the plot
ln K⁄ versus 1/T. The values of E⁄ are listed in Table 7. It is clear that,
the activation energy of PABH homopolymer is greatly higher than
its polymer complexes (1–7). Therefore, PABH is more stable than
the polymer complexes (1–7), which may be attributed to steric
hindrance. The relation between E⁄ and representative Pascal con-
stants of complexes (3–5) is shown in Fig. 9. It is observed that
the activation energy (E⁄) value of the formed polymer complexes
increases in the order NOꢁ3 > OAcꢁ > SO24ꢁ. Our results are also in

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
121
100
80
60
40
20
0
100
(1)
PABH
90
80
70
60
50
40
30
0
100
200
300
400
500
600
700
800
0
100
200
300
400
500
600
Temperature (°C)
Temperature (°C)
100
90
80
70
60
50
40
30
20
100
90
80
70
60
50
40
30
20
(2)
(3)
0
100
200
300
400
500
600
700
800
0
100
100
100
200
200
200
300
400
500
600
700
800
Temperature (°C)
Temperature (°C)
(5)
100
90
80
70
60
50
40
30
20
(4)
100
90
80
70
60
50
40
30
0
300
400
500
600
700
800
0
100
200
300
400
500
600
700 800
Temperature (°C)
Temperature (°C)
100
90
80
70
60
50
40
30
20
10
(6)
100
90
80
70
60
50
40
30
20
10
(7)
0
100
200
300
400
500
600
700
800
0
300
400
500
600
700
800
Temperature (°C)
Temperature (°C)
Fig. 8. TGA diagrams of PABH homopolymer and its polymer complexes (1–7).

122
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
Table 6
Thermal data of PABH homopolymer and its polymer complexes (1–7).
Compounda
PABH
Temperature range (°C)
TG weight loss % Found (Calc.)
Assignments
170–185
185–255
300–605
40–80
80–245
245–660
>800
40–133
133–303
303–442
442–492
>800
40–104
104–181
181–301
301–340
>800
29.95 (28.07)
43.73 (42.99)
26.32 (26.57)
5.01 (5.62)
12.22 (12.00)
45.12 (43.36)
37.60 (38.61)
4.55 (4.52)
28.54 (28.30)
35.87 (35.34)
9.97 (11.0)
21.07 (21.07)
3.73 (3.72)
CO2
C6H4N
C3H3O
2H2O
2CO2
C18H16N2O4
UO2
11 4H2O
CO2 + H2O + NH3
C13H6N
C3H3O
1
2
CuO + 2C
3
3
4
4H2O
6.40 (4.95)
H2O
CO2 + C6H5ON
NO2
C3H3O + CuO
½H2O
40.06 (41.59)
12.67 (14.12)
37.14 (37.05)
2.35 (2.53)
40–95
95–178
178–281
281–345
>800
40–105
105–354
354–560
>800
6.46 (5.06)
H2O
35.72 (35.54)
20.20 (20.40)
37.04 (36.29)
3.67 (3.55)
16.39 (16.84)
52.44 (52.87)
27.50 (27.22)
8.79 (9.53)
CO2 + C6H4
C5H5O2N
C3H3O + CuO
3
5
6
7
4H2O
SO2
CO2 + C7H9NO3
CuO + 2C
2H2O
30–90
90–320
320–580
>800
16.50 (16.40)
58.18(54.24)
21.53 (19.83)
14.92 (14.29)
27.50 (27.27)
36.56 (38.66)
21.79 (19.78)
H2O + CO2
CH3COO + C9H8NO
CoO
30–85
3H2O
85–430
430–700
>800
CO2 + CH3COO
C9 H8NO
NiO
a
The number corresponds to that used in Table 1.
Table 7
Arrhenius relationship activation energy for PABH
homopolymer and its polymer complexes (1–7).
agreement with the respective positions of these anions as given in
the representative Pascal constants [46].
Compounda
E⁄ (kJ/mol)
Kinetic studies
PABH
341.46
36.87
47.58
79.81
77.58
35.70
41.93
34.46
1
2
3
4
5
6
7
The thermodynamic activation parameters of decomposition
processes of complexes namely activation energy (Ea), enthalpy
(D (D
H⁄), entropy S⁄), and Gibbs free energy change of the
decomposition (D
G⁄) are evaluated graphically by employing the
Coast–Redfern [47] and Horowitz–Metzger [48] methods.
a
The number corresponds to that used in Table 1.
Coast–Redfern equation
The Coast–Redfern equation, which is a typical integral method,
can represent as:
where kB is the Boltzmann constant, h is the Plank’s constant and Ts
is the TG peak temperature.
ꢂ
ꢃ
Z
Z
a
T2
dx
ð1 ꢁ
A
u
Ea
RT
¼
exp
ꢁ
dt
ð11Þ
n
a
Þ
0
T1
Horowitz–Metzger equation
The Horowitz–Metzger equation is an illustrative of the approx-
imation methods. These authors derived the relation:
For convenience of integration, the lower limit T1 usually taken
as zero. This equation on integration gives:
ꢀ
ꢁ
ꢀ
ꢁ
"
#
lnð1 ꢁ
aÞ
Ea
RT
AR
uEa
1ꢁn
ln ꢁ
¼ ꢁ
þ ln
ð12Þ
1 ꢁ ð1 ꢁ
a
1 ꢁ n
Þ
Eah
T2
log
¼
for n–1
ð14Þ
)]
2:303RT2s
A plot of left-hand side (LHS) against 1/T was drawn (Fig. 10). Ea
is the energy of activation in J molꢁ1 and calculated from the slop
and A in (sꢁ1) from the intercept value. The entropy of activation
when n = 1, the LHS of equation 14 would be log[ꢁlog(1 ꢁ
a
(Fig. 11). For a first order kinetic process, the Horowitz–Metzger
D
S⁄ in (J Kꢁ1 molꢁ1) calculated by using the equation:
equation may write in the form:
ꢀ
ꢂ
ꢃꢁ
ꢀ
ꢂ
ꢃꢁ
Wa
Eh
2:303RT2s
Ah
kBTs
D
Sꢆ ¼ 2:303 log
R
ð13Þ
log log
¼
ꢁ log 2:303
ð15Þ
W
c

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
123
In the electronic spectra of the ligand and its polymeric metal
complexes, there are wide range bands were observed due to
90
80
70
60
50
40
30
p ?
p⁄ and n ? p⁄ of C@O chronopher or charge-transfer
4
either the
transition arising from
3
p-electron interactions between the metal
and ligand, which involved either a metal-to-ligand or ligand-to-
metal electron transfer [49]. The electronic spectra of the free
ligand in DMF showed strong absorption bands in the region
35,450–23,800, that could be attributed to the
p ?
p⁄ and n ? p⁄
transitions in the benzene ring or C@O groups for free ligand.
The absorption bands in the ligand changed a bit in intensity and
remained slightly changed for metal polymeric complexes. The
absorption shift and intensity change in the spectra of the metal
polymeric complexes most likely originated from the metallation,
increased the conjugation and delocalization of the whole elec-
5
tronic system and resulted in the energy change of the
p ?
p⁄
and n ? p⁄ transitions of the conjugated chromophore [50].
-40
-35
-30
-25
-20
-15
The electronic spectra of polymer complexes revealed a broad
bands in the region 18,300–18,600 and 19,800–20,200 cmꢁ1
assignable respectively to the transition 2B1g ? 2B1g and
2B1g ? 2Eg, state and is the measure of the difference between in-
plane and axial fields. Since the in-plane field is constant in all pres-
ent cases, the change in the position of the bands would be due to
the axial field only. In these copper(II) polymer complexes, the
spectral bands are found to be sensitive to the nature of the anion
Representative Pascal constants
Fig. 9. The relation between E⁄ and representative Pascal constants of polymer
complexes (3–5).
where h = T ꢁ Ts, W = W ꢁ W, W = mass loss at the completion
c
a
a
reaction; W = mass loss up to time t. The plot of log [log (W /W )]
a
c
X, and shift to higher energy in the order NOꢁ3 > OAcꢁ > SO42ꢁ
.
vs. h was drawn and found to be linear from the slope of which Ea
was calculated. The pre-exponential factor, A, calculated from
equation:
Thus, these spectral data indicating the possibility of a square
planar environment around the Cu(II) ion [51], where the ligand
is bidentate and the axial position are occupied by the anions
and/or water (Fig. 5).
Ea
A
h
ꢄ
ꢅi
¼
ð16Þ
RT2s
Ea
s
u
exp ꢁ RT
Electron spin resonance
The entropy of activation,
D
S⁄, is calculated from Eq. (13). The
enthalpy activation,
from:
D
H⁄, and Gibbs free energy,
D
G⁄, calculated
The ESR spectra of a variety of copper(II) complexes have been
measured in order to investigate the bonding character of copper–
ligand bonds in the complexes. The bonding parameters showing
the degree of covalency for the bonds have been estimated from
the magnetic parameters, namely, the g and A values, determined
from their ESR spectra [44,51]. Little attention has been paid to
the interesting and important problem of binding some correlation
between the degree of covalency thus obtained and the chemical
and physical properties of the complexes or their ligand molecules
themselves. However, it is not easy to do this because of the fact
that the ESR of the complexes is substantially concerned with only
the antibonding orbitals associated with the copper atom.
The ESR spectra of polymer complexes (2–5) are characteristic
of a d9, configuration and having an axial shape with g|| > g\ char-
acteristic of polymer complexes with 2B1g(dx2-y2) ground state. The
g-values suggest a square planar geometry [52]. The ESR parame-
ters are presented in Table 9. The average g values were calculated
according to:
D
D
Hꢆ ¼ Ea ꢁ RT
ð17Þ
ð18Þ
Gꢆ ¼
D
Hꢆ ꢁ T
D
Sꢆ
The calculated values of Ea, A,
D
S⁄,
D
H⁄ and
D
G⁄ for the decom-
position steps for PABH and its polymer complexes are summa-
rized in Table 8. The kinetic data obtained from the two methods
are comparable and can be considered in good agreement with
each other.
Electronic spectra and magnetic moments
Elemental analyses, IR and molar conductivity data were used
to prove the stoichiometry and formulation of the polymer com-
plexes. A square planar geometry were assumed for all copper(II),
nickel(II) and tetrahedral geometry was found for cobalt(II) poly-
mer complexes based on their magnetic data and spectral studies.
The Ni(II) polymer complex show diamagnetic properties and
the electronic spectrum of this complex show bands at 16,110
and 21,930 cmꢁ1 which are assigned as 1A1g ? 1A2g and
1A1g ? 1B1g transitions, respectively. The electronic spectrum of
Co(II) polymer complex show absorption band at 13,690 cmꢁ1
assignable to 4A2(F) ? 4T1(P), which is characteristic value for the
tetrahedral Co(II) complex. The magnetic moment of Co(II) is
4.61 B.M. suggesting four coordinate tetrahedral geometry.
The leff. values of the Cu(II) polymeric complexes are normal
within the range reported for one unpaired electron in a tetrahe-
dral or square planar geometry (Table 1). It is impossible to differ-
entiate between these two geometries on the basis of electronic
spectra. Instead, it may be distinguished on the basis of ESR
spectra.
ga ¼ 1=3½gjj þ 2g?ꢃ
v
:
and give values in the range 2.120–2.127. The ESR data are reported
in Table 9. The gav. values for the polymer complexes studies follow
the order:
ꢀ
ꢁ
ꢀ
ꢀ
ꢀ
ꢁ
1
2
3
4
½CuðABÞðOAcÞꢃ ꢂ H2O
>
>
>
½CuðABHÞðO2SO2Þꢃ ꢂ H2O
n
n
ꢁ
5
½CuðABÞ2ꢃ ꢂ H2O
4
n
ꢁ
3
4
½CuðABÞðONO2ÞðOH2Þꢃ ꢂ H2O
:
n
In axial symmetry, the g values are correlated by the expres-
sion = (g|| ꢁ 2)/(g\ ꢁ 2), which reflects the exchange interaction
between copper(II) centers in the solid polycrystalline complex

124
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
-11.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
-16.0
-16.5
-17.0
PABH
PABH
-11.5
-12.0
-12.5
-13.0
-13.5
170-199 oC
199-289 oC
-14.0
0.00212 0.00214 0.00216 0.00218 0.00220 0.00222 0.00224
0.00180
0.00186
0.00192
0.00198
0.00204
0.00210
(1/T(K))
(1/T(K))
-12
-13
-14
-15
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
(1)
(1)
80-245 oC
250-410 oC
0.0015
0.0016
0.0017
0.0018
0.0019
0.00196 0.00210 0.00224 0.00238 0.00252 0.00266 0.00280
(1/T(K))
(1/T(K))
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
(2)
(2)
133-299 oC
oC
310-485
0.00132 0.00138 0.00144 0.00150 0.00156 0.00162 0.00168
0.0018 0.0019 0.0020 0.0021 0.0022 0.0023 0.0024
(1/T(K))
(1/T(K))
-11.5
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-11.4
(3)
(3)
-12.0
-12.6
-13.2
-13.8
-14.4
-15.0
-15.6
197-400 oC
100-197 oC
0.0015
0.0016
0.0017
0.0018
0.0019
0.0020
0.0021
0.0022
0.0023
0.0024
0.0025
0.0026
(1/T(K))
(1/T(K))
Fig. 10. Coats–Redfern (CR) of PABH homopolymer and its polymer complexes (1–7).

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
125
-11.5
-11.5
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
-12.0
(4)
(4)
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
90-180 oC
181-374 oC
-16.0
0.00160 0.00168 0.00176 0.00184 0.00192 0.00200 0.00208
0.0022
0.0023
0.0024
0.0025
0.0026
0.0027
(1/T(K))
(1/T(K))
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-15.0
-15.5
-16.0
-16.5
(5)
(5)
360-606 oC
-15.5 100-360 oC
0.0016
0.0018
0.0020
0.0022
0.0024
0.00120
0.00128
0.00136
0.00144
0.00152
(1/T(K))
(1/T(K))
-11.5
-12
-13
-14
-15
-16
(6)
(6)
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
90-250 oC
oC
250-435
0.00196 0.00210 0.00224 0.00238 0.00252 0.00266
0.0014
0.0015
0.0016
0.0017
0.0018
0.0019
(1/T(K))
(1/T(K))
-11.5
-12.0
-12.5
-13.0
-13.5
-14.0
-14.5
-12
-13
-14
-15
-16
-17
(7)
(7)
350-550 oC
120-350 oC
0.0012
0.0013
0.0014
0.0015
0.0016
0.00168 0.00182 0.00196 0.00210 0.00224 0.00238
(1/T(K))
(1/T(K))
Fig. 10 (continued)

126
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
0.4
0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
-1.8
-2.0
-2.2
-2.4
PABH
PABH
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
W
W
W
W
199-289 oC
170-199 oC
-10
-5
0
5
10
-40
-20
0
20
40
θ (K)
θ (K)
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
0.0
-0.4
-0.8
-1.2
-1.6
(1)
(1)
W
W
W
W
80-245 oC
250-410 oC
-60
-30
0
30
60
-60
-30
0
30
60
θ (K)
θ (K)
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
-1.8
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
(2)
(2)
W
W
W
W
133-299 oC
310-485 oC
-80
-60
-40
-20
0
20
40
60
80
-80
-60
-40
-20
0
20
40
60
80
θ (K)
θ (K)
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
0.4
0.0
(3)
(3)
-0.4
-0.8
-1.2
-1.6
-2.0
W
W
W
W
197-400 oC
100-197 oC
-88
-66
-44
-22
0
22
44
66
88
-40
-30
-20
-10
0
10
20
30
40
θ (K)
θ (K)
Fig. 11. Horowitz–Metzger (HM) of PABH homopolymer and its polymer complexes (1–7).

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
127
0.0
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
-1.8
(4)
(4)
-0.3
-0.6
-0.9
-1.2
-1.5
-1.8
W
W
W
W
181-374 oC
90-180 oC
-120 -90
-60
-30
0
30
60
90
120 150
-40
-30
-20
-10
0
10
20
30
40
θ (K)
θ (K)
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
-1.8
0.3
(5)
(5)
0.0
-0.3
-0.6
-0.9
-1.2
-1.5
-1.8
W
W
W
W
360-606 oC
100-360 oC
-90
-60
-30
0
30
60
90
-120
-90
-60
-30
0
30
60
90
120
θ (K)
θ (K)
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
0.0
(6)
(6)
-0.4
-0.8
-1.2
-1.6
W
W
W
W
250-435 oC
90-250 oC
-90
-60
-30
0
30
60
90
-60
-30
0
30
60
θ (K)
θ (K)
0.4
0.0
0.2
0.0
(7)
(7)
-0.2
-0.4
-0.6
-0.8
-1.0
-1.2
-1.4
-1.6
-0.4
-0.8
-1.2
-1.6
-2.0
W
W
W
W
350-550 oC
120-350 oC
-90
-60
-30
0
30
60
90
-90
-60
-30
0
30
60
90
θ (K)
θ (K)
Fig. 11 (continued)

128
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
Table 8
Thermodynamic activation energy for PABH homopolymer and its polymer complexes (1–7).
Compounda
Temp. range (°C)
Method
Parameter
Ea (kJ molꢁ1
)
A (sꢁ1
)
D
S⁄ (J molꢁ1 Kꢁ1
)
D
H⁄ (kJ molꢁ1
)
D )
G⁄ (kJ molꢁ1
PABH
170–199
199–289
80–245
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
HM
CR
341
344
2.58E+36
5.17E+37
2.27E+06
2.50E+07
5.80E+00
1.50E+02
1.21E+03
2.18E+04
1.51E+01
7.41E+02
1.00E+03
1.64E+04
1.73E+04
3.27E+05
5.57E+03
7.02E+04
6.65E+06
1.45E+08
3.63E+03
6.82E+04
7.15Eꢁ01
3.48E+01
4.35E+04
7.33E+05
2.19E+01
3.91E+0
4.49E+02
4.74E+02
337
340
80.3
131
123
146
146
129
124
178
174
147
140
198
194
121
118
166
164
118
114
161
157
152
145
223
219
129
126
183
177
150
147
215
208
84.6
94.5
30.8
38.1
67.0
77.5
40.0
49.2
73.1
85.1
54.7
61.9
68.7
78.4
73.8
79.9
65.3
75.2
29.4
39.0
106
ꢁ1.28E+02
ꢁ1.08E+02
ꢁ2.33E+02
ꢁ2.06E+02
ꢁ1.92E+02
ꢁ1.68E+02
ꢁ2.26E+02
ꢁ1.94E+02
ꢁ1.94E+02
ꢁ1.71E+02
ꢁ1.67E+02
ꢁ1.42E+02
ꢁ1.79E+02
ꢁ1.58E+02
ꢁ1.17E+02
ꢁ9.13E+01
ꢁ1.82E+02
ꢁ1.57E+02
ꢁ2.52E+02
ꢁ2.20E+02
ꢁ1.64E+02
ꢁ1.40E+02
ꢁ2.23E+02
ꢁ1.99E+02
ꢁ1.96E+02
ꢁ1.69E+02
ꢁ2.47E+02
ꢁ2.24E+02
ꢁ1.38E+02
ꢁ1.10E+02
90.2
27.2
34.5
62.0
72.4
36
45.1
67.5
79.6
51.2
58.4
63.9
73.7
70.4
76.5
60.8
70.6
25.2
34.8
99.6
1
2
3
4
5
6
7
250–410
133–299
310–485
100–197
197–400
90–180
181–374
100–360
360–606
90–250
119
113
34.4
42.1
67.6
78.3
28.4
37.6
121
30.7
38.4
62.5
73.1
24.2
33.4
250–435
120–350
350–550
7.74E+02
1.83E+04
1.27E+00
2.13E+01
9.02E+05
2.71E+07
115
129
HM
135
a
The number corresponds to that used in Table 1.
[53] Accordingly, if G < 4, then the exchange interaction may be
present, if G > 4, then the exchange interaction may be negligible;
however, which is the case in the polymer complexes under inves-
tigation. Interestingly, in these complexes, G > 4, suggesting the
presence of an exchange interaction may be negligible. The mag-
netic moments of these polymer complexes are normal at room
temperature. The G values follow the order:
A|| polymer complexes exhibit g|| < 2.3, suggesting covalent
characters of the copper–ligand bonding in the present polymer
complexes. The g||/A|| is taken as an indication for the stereochem-
istry of the copper(II) polymer complexes. Addison has suggested
that this ratio may be an empirical indication of the tetrahedral
distortion of the square planar geometry [54]. The values lower
than 135 cmꢁ1 are observed for square planar structures and those
higher than 150 cmꢁ1 for tetrahedrally distorted complexes. The
values for the polymer complexes under investigation. Table 9,
showed that all polymer complexes associated with a square pla-
nar ligand around the copper(II) centers. The g||/A|| values lie just
within the range expected for the complexes.
ꢀ
ꢁ
ꢀ
ꢀ
ꢀ
ꢁ
3
4
5
½CuðABÞ2ꢃ ꢂ H2O
4
½CuðABÞðONO2ÞðOH2Þꢃ ꢂ H2O
>
>
>
n
n
ꢁ
1
½CuðABÞðOAcÞꢃ ꢂ H2O
2
n
ꢁ
2
The g-values of the copper(II) polymer complexes with a B1g
ground state (g|| > g\) may be expressed [55] by:
3
4
½CuðABHÞðO2SO2Þꢃ ꢂ H2O
:
n
g ¼ 2:0023 ꢁ ð8K2k0=
D
Exy
Þ
This is consistent with the order of the strength of metal–anion
jj
jj
interactions, i.e. nitrate > acetate > sulfate. Our results are also in
agreement with the respective positions of these anions as given
in the representative Pascal constants [46].
g? ¼ 2:0023 ꢁ ð2K2 k0=
D
Exz
Þ
?
Table 9
ESR spectral and calculated bonding parameters for the Cu(II) complexes (2–5).
b
c
Complexa
g||
g\
gav.
G
a2
A||
g||/A||
D
Exy (cmꢁ1
)
D
Exz (cmꢁ1
)
K\2
K2||
K2
b2
b12
2
3
4
5
2.246
2.260
2.258
2.250
2.057
2.045
2.061
2.060
2.120
2.117
2.127
2.123
4.32
5.78
4.20
4.17
0.80
0.93
0.90
0.84
177
221
196
167
127
102
115
134
18310
18590
18570
18550
19810
20215
20195
20090
0.685
0.525
0.719
0.695
0.675
0.724
0.720
0.700
0.67
0.60
0.72
0.70
0.82
0.56
0.80
0.84
0.84
0.78
0.80
0.83
a
b
c
The number corresponds to that used in Table 1.
A values in 10ꢁ4 (cmꢁ1).
The unit (cmꢁ1).

M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
129
(a)
(b)
3
A x 10-4 (cm-1)
ll
220
2.260
3
4
g
av.
210
200
190
180
170
2.255
2.250
2.245
4
5
5
2
2
0.78
0.80
0.82
0.84
0.86
α2
0.88
0.90
0.92
0.94
Fig. 12. The relation between a2 vs. (a) A|| ꢄ 10ꢁ4 (cmꢁ1) and (b) gav.
(b)
(a)
230
0.94
0.92
0.90
0.88
0.86
0.84
3
A x 10-4 cm-1
(
)
ll
220
210
200
190
180
170
160
3
2
α
4
α2
4
5
5
-45
-40
-35
-30
-25
-20
-15
Representative Pascal constants
Fig. 13. The relation between representative Pascal constants of complexes (3–5) and (a) A|| ꢄ 10ꢁ4 (cmꢁ1) and (b) a2
.
3
(a)
4
(b)
5
2.260
2.256
2.252
2.248
2.244
2.060
2.056
2.052
2.048
2.044
4
2
5
2
3
0.52
0.56
0.60
0.64
0.68
0.72
0.68
0.70
0.72
0.74
2
ll
2
T
k
k
Fig. 14. The relation between (a) K2|| vs. g|| and (b) K2\ vs. g\
.
where K|| and K\ are the parallel and perpendicular components
respectively of the orbital reduction factor (K), k0 is the spin–orbit
tron transition energies of 2B1g ? 2B1g and 2B1g ? 2Eg From the
above relations, the orbital reduction factor (K||, K\, K), which are
a measure of covalency [55], can be calculated. For an ionic environ-
coupling constant for the free copper,
DExy and DExz are the elec-

130
M.M. Ghoneim et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 111–131
groups enhances the electron density on the coordination sites
230
220
210
200
190
180
170
160
and simultaneously increase the value of ESR parameters (Table 9).
The plot of A|| vs. g|| (Fig. 15) shows a linear relationship
between A|| and g|| for each chromophore. The A|| and g|| values
are relatively insensitive to the inductive effect of the co-ligand
and chiefly depend on the stereochemical factors. The g|| values
are weaker in the ‘‘O,O’’ compounds in agreement with the more
electron donating character of the nitrogen atom.
3
4
2
Conclusion
5
The structures of the Cu(II), Co(II), Ni(II) and UO2(II) ions poly-
mer complexes of ABH were confirmed by elemental analyses, IR,
1H NMR, molar conductance and thermal analysis data. Therefore,
from IR spectrum, it is concluded that ABH binds to the metal ions
through protonated carboxylate O and phenolic OH [except com-
plex (5)]. Three types of polymeric complexes were prepared. In
type [(1) & (2)](1:2) (monobasic and bis-bidentate) the chelate
rings are six-membered/four coordinate, whereas in type [(3) &
(4)](1:1) (monobasic and bidentate) they are six-membered/four
coordinate, monobasic and bidentate. In type [5](1:1) (neutral
and bidentate) the chelate is six-membered/four coordinate. While
in case of complex (5), it coordinates via its COOH/OH. From the
molar conductance, it is found that all polymer complexes are
non-electrolytes. The 1H NMR spectra of ABH and its UO2(II) poly-
mer complex show that the COOH signal in the free ligand is com-
pletely disappeared in the spectrum of the UO2(II) polymer
complex indicating the involvement of the COOH group in chela-
tion through displacement of the COOH proton. The values of acti-
vation energies of decomposition (E⁄) are found to be 341.46,
36.87, 47.58, 79.81, 77.58, 35.70, 41.93 and 34.46 kJ/mol for PABH
and its polymer complexes (1–7), respectively. It is clear that, the
activation energy of PABH is greatly higher than its polymer com-
plexes (1–7).
2.245
2.250
2.255
2.260
2.265
g
ll
Fig. 15. The relation between g|| vs. A|| ꢄ 10ꢁ4 (cmꢁ1).
ment, K = 1 and for a covalent environment K < 1, the lower value of
K, the greater is the covalency.
K2? ¼ ðg? ꢁ 2:0023Þ
D
E
xz=2k0
K2jj ¼ ðgjj ꢁ 2:0023Þ
DE
xy=8k0
K2 ¼ ðK2jj þ K2?Þ=3
The K values (Table 9) for the copper(II) polymer complexes are
indicative of their covalent nature [56]. Kivelson and Neiman [22]
noted that, for an ionic environment, g|| P 2.3. Theoretical work by
Smith [57] seems to confirm this view. The g||-values reported here
show considerable covalent bonding character. Also, the in-plane
r
-covalency parameter a2 was calculated. The calculated values
(Table 9) suggest covalent bonding nature [58].
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p
-bonding coefficient (b21 and b,
respectively) are dependent upon the values of
the following equations [58]:
DExy and DExz in
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