Spectral studies, thermal investigation and biological activity of some metal complexes derived from (E)-N′-(1-(4-aminophenyl)ethylidene)morpholine-4-carbothiohydrazide

Article abstract of DOI:10.1016/j.molstruc.2017.05.014

A new series of biologically active Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes derived from the novel thiosemicarbazone ligand; (E)-N′-(1-(4-aminophenyl)ethylidene)morpholine-4-carbothiohydrazide (HL) were synthesized. The mode of bonding of the ligand and the geometrical structures of its metal complexes were achieved by different analytical and spectral methods. The ligand coordinated with metal ions in a neutral bidentate fashion through the thione sulfur and azomethine nitrogen atoms. All metal complexes adopted octahedral geometry, except Cu(II) complexes (3, 6, 7) which have a square planar structure. The general thermal decomposition pathways of the ligand along with its metal complexes were explained. The thermal stability of the complexes is controlled by the number of outer and inner sphere water molecules, ionic radii and the steric hindrance. The activation thermodynamic parameters; (activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*) and Gibbs free energy (ΔG*)) along with order of reaction (n) were estimated from DTG curves. The ESR spectra of Cu(II) complexes indicated that (d_x2-y2)¹ is the ground state with covalence character of metal–ligand bonds. The molluscicidal and biochemical effects of the ligand and its Ni(II); Cu(II) complexes (2; 3, 5, 7) along with their combinations with metaldehyde were screened in?vitro on the mucous gland of Eobania vermiculata. The tested compounds exhibited a significant toxicity against the tested animals and have almost the same toxic effect of metaldehyde which increases the mucous secretion of the snails and leads to death.

Full text of DOI:10.1016/j.molstruc.2017.05.014

Accepted Manuscript
Spectral studies, thermal investigation and biological activity of some metal
complexes derived from (E)-N′-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide
El-Sayed A. El-Samanody, Magdy W. Polis, Esam M. Emara
PII:
S0022-2860(17)30594-X
10.1016/j.molstruc.2017.05.014
MOLSTR 23755
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 13 January 2017
Revised Date: 30 March 2017
Accepted Date: 4 May 2017
Please cite this article as: E.-S.A. El-Samanody, M.W. Polis, E.M. Emara, Spectral studies,
thermal investigation and biological activity of some metal complexes derived from (E)-N′-(1-(4-
aminophenyl)ethylidene)morpholine-4-carbothiohydrazide, Journal of Molecular Structure (2017), doi:
10.1016/j.molstruc.2017.05.014.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
Spectral studies, thermal investigation and biological activity of some metal
complexes derived from (E)-N'-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide
a
b
b
El-Sayed A. El-Samanody , Magdy W. Polis , Esam M. Emara *
a
:
Chemistry Department, Faculty of Science, Menoufia University, Shebin El-Kom, Egypt.
Plant Protection Researches Institute, Agricultural Researches Center, Giza, Egypt.
b
:
Graphical Abstract
CH3
CH3
O
H
N
N
N
N
HN
S
S
H N
2
H N
2
N
O
E-isomer
Z- isomer
Proposed structure for the thiosemicarbazone ligand (HL)
1

ACCEPTED MANUSCRIPT
Abstract
A new series of biologically active Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes derived
from the novel thiosemicarbazone ligand; (E)-N'-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide (HL) were synthesized. The mode of bonding of the ligand and the geometrical
structures of its metal complexes were achieved by different analytical and spectral methods. The
ligand coordinated with metal ions in a neutral bidentate fashion through the thione sulfur and
azomethine nitrogen atoms. All metal complexes adopted octahedral geometry, except Cu(II)
complexes (3, 6, 7) which have a square planar structure. The general thermal decomposition pathways
of the ligand along with its metal complexes were explained. The thermal stability of the complexes is
controlled by the number of outer and inner sphere water molecules, ionic radii and the steric
hindrance. The activation thermodynamic parameters; (activation energy (E*), enthalpy of activation
(
∆H*), entropy of activation (∆S*) and Gibbs free energy (∆G*)) along with order of reaction (n) were
1
estimated from DTG curves. The ESR spectra of Cu(II) complexes indicated that (dx2-y2 ) is the ground
state with covalence character of metal–ligand bonds. The molluscicidal and biochemical effects of the
ligand and its Ni(II); Cu(II) complexes (2; 3, 5, 7) along with their combinations with metaldehyde
were screened in vitro on the mucous gland of Eobania vermiculata. The tested compounds exhibited a
significant toxicity against the tested animals and have almost the same toxic effect of metaldehyde
which increases the mucous secretion of the snails and leads to death.
Keywords: Thiosemicarbazone; spectral studies; thermal investigation; molluscicidal activity;
biochemical measurements
*
Corresponding author. E-mail address: esamemara@ymail.com (Esam M. Emara)
2

ACCEPTED MANUSCRIPT
1
. Introduction
Thiosemicarbazones act as chelating agents with transition metal ions, bonding via thione sulfur
and azomethine nitrogen atoms [1]. The thiosemicarbazone moiety is planar and adopts an extended
conformation due to the extensive π-electron delocalization throughout the moiety [2]. Since the
thiosemicarbazone ligands have variable binding modes, the behavior of these modes is explored as
their transition metal complexes [3-5]. Thiosemicarbazones and their metal complexes exhibit
numerous medicinal, pharmacological and biological activities [1-3, 6]. Particularly, the
thiosemicarbazones can be used as analytical reagents for the determination of metals and as devices
for optical storage and optical information processing [1, 7]. Morpholine is a cyclic secondary amine
which contains both the amine and ether groups and is suitable for extractive distillation and solvent
application in the petrochemical industries [8]. Morpholine derivatives are widely used as versatile
synthetic units in organic synthesis for the construction of agrochemical, fungicides and bactericides.
Many compounds of this class were reported to possess anti-inflammatory, analgesic, local anesthetic,
anti-HIV, anti-cancer, appetite suppressant, anti-depressant, antifungal and antimicrobial activity [9,
1
0]. The land snail; Eobania vermiculata has a destructive effect to citrus species and also feed on the
foliage of many gardens and ornamental plants. Therefore, the control of these snails is becoming very
important [11, 12]. The chemical control of pest snail communities through the application of
pesticides is still the most effective approach, particularly over large area. However, the presence of
agrochemicals in high concentrations in soil may induce mortality in non-target species like vertebrate
animals and human beings and lead to pollution of environment. Thus, application with lower
concentrations in snail combat is expected to avoid such a hazard [12]. The present study oriented to
investigate the mode of chelation of (E)-N'-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide ligand towards some transition metals based on elemental analyses, spectral and
thermal studies. Also, this study was focused to evaluate the effect of this ligand and some of its
prepared metal complexes on the mucous gland of Eobania vermiculata.
3

ACCEPTED MANUSCRIPT
2
. Experimental
2
.1. Materials and methods
All the chemicals and solvents employed in the synthesis were of analytical grade (BDH, Merck
and Sigma Aldrich) and were used as received.
Elemental analyses (C, H, N and S) were reported at Main Defense Chemical Laboratory on a
Perkin Elmer-2400 elemental analyzer. Metal ions of the obtained complexes were estimated
complexometrically [13]. Furthermore, chloride and bromide ions were specified by using Mohr's
method [13]. Fast Atom Bombardment mass spectrum (FAB-MS) for the ligand was performed on a
-1
Shimadzu Qp-2010 Plus spectrometer. Infrared spectra were conducted in range (4000–400 cm ) on a
1
Nicolet FT-IR spectrophotometer. The H NMR spectra were carried out by using DMSO-d on a
6
Varian Gemini 200 NMR spectrometer at 300 MHz. The absorption electronic spectra were measured
in Nujol mulls using a Perkin Elmer Lambda 4B spectrophotometer. Molar conductivity measurements
-3
were obtained in DMF solution (10 M) using CD6N Tacussel conductimeter. The electron spin
resonance (ESR) spectra were given by Bruker BioSpin GmbH. Measurements were effected in the X-
band frequency 9.714 GHz on a microcrystalline powder at room temperature; the microwave power
was around 2.012 mW. The thermal analyses (TG/DTG) were reported by using a Shimadzu DAT/TG–
ο
5
0 thermal analyzer at a heating rate of 10 C/min under N atmosphere with a flowing rate of 20
2
ο
mL/min over the range (25–900 C) using platinum crucibles. Magnetic susceptibilities were measured
at room temperature by a modified Gouy method using a Johnson Matthey magnetic susceptibility
’
balance. Pascal s constants were used to calculate the diamagnetic corrections [14]. The effective
magnetic moment calculations were obtained from the equation; ꢀꢁꢂꢂꢃ = 2.84(ꢄꢅꢆꢇꢈꢈꢉꢃꢊ)ꢋ/ꢌ. Melting
points were measured by using Stuart melting point apparatus. Biochemical measurements were
performed at Plant Protection Researches Institute, Giza, Egypt.
2
.2. Synthesis of the thiosemicarbazone ligand; (E)-N'-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide (HL)
4

ACCEPTED MANUSCRIPT
4
-morpholinethiosemicarbazide was prepared according to the published literature [15]. The
entitled ligand was prepared by adding the dissolved 0.1 mol (13.52 g) of p-aminoacetophenone to 0.1
mol (16.12 g) of 4-morpholinethiosemicarbazide in hot ethanol. The reaction mixture was catalyzed by
adding few drops of concentrated H SO acid after an hour of starting the reaction. The obtained yellow
2
4
precipitate was filtered off, washed several times with ethanol and dried in a vacuum desiccator over
anhydrous CaCl2.
2
.3. Synthesis of the thiosemicarbazone metal complexes
2 2
The metal complexes derived from the reaction of the ligand with MCl .nH O; (M = Co(II),
Ni(II), Cu(II), Zn(II) and Cd(II); n = 0–6) and other copper(II) salts (acetate, bromide, perchlorate)
were synthesized. 0.01 mol of an ethanolic solution (35 mL) of the appropriate metal salt was added
dropwise to 0.01 mol of a hot ethanolic solution of the ligand in (1L:1M) molar ratio. The reaction
ο
mixture was refluxed for 4 hours at 80 C. The formed complexes were filtered off, washed several
times with ethanol and dried in a vacuum desiccator over anhydrous CaCl . Moreover, the Cu(II) and
2
Zn(II) chloride complexes were re-prepared by (2L:1M) molar ratio in order to investigate the effect of
changing the molar ratio on the stoichiometry of the separated complexes. Analytical and physical data
of the thiosemicarbazone ligand (HL) and its metal complexes are tabulated in Table 1.
Insert Table 1 and its caption here
2
2
.4. Biological studies
.4.1. Tested snails
The molluscicidal activity of the thiosemicarbazone ligand (HL) as well as its Ni(II); Cu(II)
complexes (2; 3, 5, 7) against Eobania vermiculata was evaluated. The tested snails were collected
from untreated fields at Sadat city, Menoufia governorate, Egypt. The muslin bags were used to
transfer the collected snails directly to the laboratory at which the animals kept in a small plastic boxes
filled with moist optimal soil provided with fresh green lettuce leaves for two weeks for adaptation.
Adult healthy animals with almost the same shell diameter were utilized and starved for 24 hours
5

ACCEPTED MANUSCRIPT
before treatments. The treatments were carried out by using contact technique [16]. Four concentrations
(
300, 200, 100, 50 ppm) of the tested compounds were prepared by using DMF. A parallel control test
was conducted.
2
.4.2. Biochemical measurements
Eobania vermiculata was treated with LC50 of the tested compounds and their mixtures with
metaldehyde in order to assess the activities of alanine amino transaminase (ALT), aspartate amino
transaminase (AST) and total proteins (TP) [17, 18]. The biochemical tests were conducted under
laboratory conditions after three days of treatments. Shells of the tested snails were removed by making
a cut around the whorls in a continuous manner starting at the aperture opening using bone scissors and
the shell broken fragments were carefully removed. The tissues of the animals were dissected out,
homogenized in distilled water, centrifuged at 8000 rpm for 15 min at 5ºC in a refrigerated centrifuge
and then kept in a freezer.
2
.4.3. Statistical analysis
The values of LC50 with slope and fiducial limits of each treatment were estimated by using
Probit analysis program [19]. The results were estimated as Mean±SD and were subjected to analysis
of variance technique (ANOVA). The means were compared, for significance, by LSD method at the
probability of 0.05 [20].
3
. Results and discussion
Table (1) illustrates the colors, elemental analyses, chemical formulae, melting points and molar
conductivity values of the prepared compounds. Metal complexes with different stoichiometry; 1:1 and
:2 (M:L) arise from the reactions of the thiosemicarbazone ligand (HL) with different metal salts. All
obtained metal complexes are stable, non-hygroscopic and freely soluble in DMF and DMSO. The
1
-1
2
-1
molar conductance values are within ranges; (3–23), (57–76) and 112 ꢀ cm mol , indicating to non-
electrolytic nature of (1, 6-10) complexes [16, 21], 1:1 electrolyte for complexes (2, 3, 5) [22] and 1:2
electrolyte for complex (4) [23], respectively (Table 1).
6

ACCEPTED MANUSCRIPT
3
.1. Mass spectra
The (FAB-MS) of the thiosemicarbazone ligand (HL) (Fig. 1) displays a molecular ion peak at
m/z = 278 amu, corresponding to the calculated theoretical molecular weight. This value proposed the
chemical formula (C H N SO) which based on the elemental analyses data of the ligand. The
1
3
18
4
spectrum also reveals additional degradations equivalent to a series of molecular ion peaks appeared at
+
+
m/z = 263, 191, 133, 118, 92 and 65 amu, matches with the fragment ions; [C H N SO] , [C H N S] ,
13
16
3
9
8
3
+
+
+
+
[
C
8
H
8
N
2
] , [C
8
H
7
N] , [C
7
H
7
] and [C
Insert Fig. 1 and its caption here
.2. H NMR spectra of the thiosemicarbazone ligand and its metal complexes
The thiosemicarbazone ligand contains a π-system of the azomethine bond which enriches the
5 5
H ] , respectively.
1
3
basis of Z-E stereoisomerism. These stereoisomers may be stabilized by electron lone pairs of nitrogen
1
and sulfur atoms. The H NMR spectrum of the ligand displays two signals at δ 10.47 and 9.87 ppm
with integral ratio (1:2), ascribed to NH proton of Z and E stereoisomers, respectively [24, 25] (Table
2
). The spectrum shows signals at δ (6.53–7.99), 5.44, (3.07–3.82) and (2.15–2.48 ppm) ranges,
assignable to aromatic ring, NH , CH and CH protons, respectively [16, 26–29]. The signals at δ
0.47, 9.87 and 5.44 ppm disappeared in the presence of D O, confirming their assignment as NH and
NH , respectively.
2
2
3
1
2
2
The spectra of Zn(II), Cd(II) complexes (8, 9, 10) exert resonances corresponding to protons of
aromatic ring, NH , solvents (coordinated or crystallized), CH and CH groups, assignable by signals
2
2
3
within ranges; δ (6.44–7.99), (5.49–5.59), (3.83–3.89), (3.07–3.82) and (2.14–2.47 ppm), respectively.
Those signals are almost at the same positions in the ligand. The spectra of the complexes reveal NH
signal in range δ (9.91–10.39 ppm) with the absence of SH signal in range (12–13 ppm), indicating that
the ligand binds with metal ions in a neutral thione form which is compatible with infrared
assignments. The spectra of Zn(II) and Cd(II) complexes (8, 10) exhibit only the NH signal of E form
at δ 10.11 and 9.92 ppm, respectively (Table 2), established that those complexes are separated in E
7

ACCEPTED MANUSCRIPT
isomer only. Meanwhile, the spectrum of Zn(II) complex (9) shows two signals of NH group (δ 9.91
and 10.39 ppm), considering that the complex exists in Z/E isomers.
Insert Table 2 and its caption here
3
.3. IR spectra of the thiosemicarbazone ligand and its metal complexes
The comparison between the IR spectra of the ligand and prepared metal complexes gives an
insight into the binding behavior of the ligand. The most prominent IR spectral features of the ligand
and its metal complexes are tabulated in Table (3) and shown in Fig. (2). The IR spectrum of the
-1
thiosemicarbazone ligand displays bands at 1533, 1291, 1223, 904 and 505 cm , attributed to
thioamide bands I (δ(NH) + υ(C=N), II (δ(NH) + υ(C–N)), III (υ(C–N) + υ(C=S)), IV (υ(C=S)) and
γ(C=S), respectively [30, 31]. The υ(NH ), υ(NH), υ(N–NH) and γ(NH) bands are located at 3375,
2
-1
3
236, 1036 and 694 cm , respectively [30b, 32, 33]. These data are gathered with the absence of υ(SH)
-1
in range (2500–2600 cm ) to suggest that the ligand exists mainly in the thione rather than the thiol
-1
form. The υ(C=N) band overlapped with δ(NH ) and appears as a strong band at 1620 cm [6].
2
-1
Additional bands are observed at 1427 and 1374 cm , characteristic for CH and CH deformation,
2
3
respectively [16, 34].
Insert Fig. 2 and its caption here
Insert Table 3 and its caption here
-1
The IR spectra of prepared metal complexes show that the υ(C=N) of the ligand (1620 cm )
-1
undergoes (blue/red) shift by (2–19) and (2–13 cm ) in all complexes, respectively. On the other hand,
-1
-1
the δ(NH) of the ligand (1533 cm ) shifted to higher/lower wavenumbers by (5–61 cm ) upon
complexation. Also, the υ(N–NH) and γ(NH) bands of the ligand suffered changes in their intensity and
position upon chelation. Furthermore, the spectra of the prepared metal complexes display new bands
-1
within range (424–477 cm ), ascribed to υ(M–N) [35]. The aforesaid data established the contribution
of the azomethine nitrogen atom in chelation.
8

ACCEPTED MANUSCRIPT
The thioamide ligand bands are strongly affected upon complexation (Table 3). The υ(C=S) and
-1
-1
γ(C=S) ligand bands (904, 505 cm ) undergo (blue/red) shift by (13–33) and (5–41 cm ) upon
chelation, respectively. The above observations gathered with the absence of υ(SH) band, indicating
that the ligand coordinated with metal ions through sulfur atom of the thione group. The stretching
vibrations of NH and NH groups are not clearly assignable due to overlapping with υ(OH) of lattice
2
-1
solvents within range (3401–3473 cm ) [24]. Moreover, the spectra of the complexes display bands at
-1
(
1637–1646) and (618–661 cm ) ranges, due to coordinated water molecules [31, 36]. The spectra
-1
show a significant new band within range (470–496 cm ), due to υ(M–O) [37]. Cu(II) acetate complex
͞
͞
-1
(
6) shows νas(COO ) and νsy(COO ) at 1576 and 1392 cm , respectively, indicating a monodentate
acetate coordination [16]. While, Cu(II) perchlorate complex (7) displays a splitted strong bands (ν ) at
3
-1
-1
(
1115, 1080 cm ) and a strong band (ν ) at 630 cm , in agreement with a monodentate coordination of
4
perchlorate [16].
The above arguments concluded that the ligand chelated in a neutral bidentate fashion through the
azomethine nitrogen and thione sulfur atoms (NS type). Based on analytical and spectral studies (IR,
1
H NMR, mass), the chemical structure of the thiosemicarbazone ligand (HL) may be proposed as
shown in Scheme 1.
Insert Scheme 1 and its caption here
3
.4. Molecular modeling study of the thiosemicarbazone ligand (HL)
The molecular modeling of the chemical structure of the thiosemicarbazone ligand (HL) was
+
carried out by using (MM ) calculations in order to have fundamental features of the electronic
structure as well as the stereochemistry of the ligand [38]. Moreover, the molecular mechanisms
+
(
MM ) have massive applications in coordination chemistry [38]. The molecular modeling of the
ligand (Fig. 3 and Table 4) displays numbering of its skeleton.
Insert Fig. 3 and its caption here
Insert Table 4 and its caption here
9

ACCEPTED MANUSCRIPT
3
.5. Electronic spectra and magnetic moments of the thiosemicarbazone ligand (HL) and its metal
complexes
The electronic absorption spectra are important techniques for elucidating the stereochemistry of
metal complexes. The electronic spectrum of the thiosemicarbazone ligand displays a medium
absorption band at 265 nm, attributed to π-π* electronic transition of the phenyl ring [38]. This band
suffers (red/blue) shift upon complexation with metal ions (Table 5). Moreover, the chromophores of
the ligand ((C=N) and (C=S)) are observed at 320 and 367 nm, respectively [38, 39]. The n-π*
transition bands undergo change in both intensity and position in all complexes, indicating the
involvement of the azomethine nitrogen and thione sulfur atoms in chelation. The ligand to metal
charge transfer (LMCT) bands of metal complexes appear as a strong broad band in range (467–412
nm) [16].
4
Co(II) complex (1) exhibits (d–d) transition bands at 687 and 586 nm, assigned to T (F) →
1
g
4
4
4
A (P) (υ ) and T (F) → T (P) (υ ) transitions, respectively [16, 40]. These bands are consistent
2
g
2
1g
2g
3
with the magnetic moment value (5.07 B.M.) to establish a high spin octahedral geometry around
Co(II) ion (Table 5) [16].
The (d–d) electronic transitions of Ni(II) complex (2) appear at 681 and 518 nm, ascribed to
3
3
3
3
A (F) → T (F) (υ ) and A (F) → T (P) (υ ) transitions, respectively, characteristic for an
2
g
1g
2
2g
1g
3
octahedral geometry for Ni(II) ion [16, 26]. The magnetic moment value (3.56 B.M.) supports a further
evidence for octahedral Ni(II) ion [16, 38] (Table 5).
The electronic spectra of Cu(II) complexes (3, 6, 7) show two intense bands in ranges; (688–679)
2
2
2
2
and (561–526 nm), corresponding to B → E and B → A transitions, respectively (Table 5),
1
g
g
1g
1g
indicate a square planar geometry around Cu(II) ions [38, 40–42]. However, the electronic spectra of
Cu(II) complexes (4, 5) display two absorption bands at (671, 564) and (682, 544 nm), assignable to
2
2
2
2
B
g
1g → B2g and B1g → E transitions, respectively (Table 5). The magnetic moment values for Cu(II)
1
0

ACCEPTED MANUSCRIPT
complexes (3-7) lie in range (1.70–1.86 B.M.). This value is in agreement with the spin value of one
electron [38, 41, 42].
The aforementioned data confirmed the proposed chemical structure for metal complexes shown
in Scheme 2.
Insert Table 5 and its caption here
Insert Scheme 2 and its caption here
3
.6. Thermal analysis of the ligand and its metal complexes
The results achieved from the thermal analyses (TG, DTG) of the ligand and its metal complexes
are listed in Table (6) and Fig. (4). The thermodynamic and kinetic parameters of the
thiosemicarbazone ligand and its metal complexes were estimated [16] and represented in Table (7).
The TG curve pattern of the thiosemicarbazone ligand (HL) establishes that the ligand is thermally
ο
ο
stable up to 133 C with insignificant mass loss below 100 C, due to releasing of residual solvent (0.25
H O) from the tested sample [38]. The ligand undergoes thermal decomposition through two steps in
2
ο
ο
temperature ranges; (133–505 C) and (505–712 C). The first step shows 55.47% TG weight loss,
corresponding to the removal of morpholinethiosemicarbazide moiety (C SO) via breaking the
5
7 3
H N
azomethine bond. This step is associated with three successive DTG peaks at (Tmax.= 169, 201 and
ο
3
07 C). However, the second decomposition step associated with 42.20% TG weight loss, assignable to
ο
complete ligand pyrolysis. This step is characterized by a strong DTG peak at (Tmax.= 611 C), Table
(
6). The proposed thermal decomposition mechanism for the ligand is shown in Scheme (3).
Insert Fig. 4 and its caption here
Insert Scheme 3 and its caption here
ο
The desolvation and/or dehydration stage of metal complexes occurs within range (18–226 C).
All metal complexes (except Cu(II); Zn(II), Cd(II) complexes (4, 5; 9, 10)) decomposed firstly with the
removal of coordinated anions due to weak bonding between metal and anions [43]. Sometimes, the
removal of ionic chloride associated with coordinated anions and coordinated water [44]. In case of
1
1

ACCEPTED MANUSCRIPT
Cu(II); Zn(II), Cd(II) complexes (4, 5; 9, 10), the elimination of coordinated anions overlapped with
partially ligand pyrolysis [45]. The lower onset and broad temperature range for the removal of
solvents of crystallization indicate that the solvents are not involved in lattice voids. While, the higher
temperature of the removal of the rest solvents in case of Cu(II) and Cd(II) complexes (5, 10) reassures
that the rest solvents exist in the lattice structure [16, 41].
[
Co(HL)Cl (H O) ].2.75H O complex (1) is used as a representative example to explain the
2 2 2 2
decomposition pathway for Ni(II); Cu(II); Zn(II) complexes (2; 3, 6; 8) (Scheme 4). The TG curve of
ο
Co(II) complex (1) displays 10.09% TG weight loss in (19–192 C) range, attributed to dehydration
ο
process (Table 6). This step has a weak DTG peak at (Tmax.= 37 C). After that, the thermal
decomposition starts and achieved in three continuation steps. The first one associates with 21.06% TG
ο
weight loss up to 262 C, equivalent to the removal of coordinated chlorides as well as two mole of
ο
coordinated water molecules. Meanwhile, the second decomposition step takes place up to 431 C with
TG weight loss 23.91%. This is convenient with the pyrolytic process started with the rapture of
azomethine group to release 4-ethylbenzenamine moiety. This process is characterized by DTG peak at
ο
(
T
max.= 305 C). While, the last degradation step including a five membered ring metal chelates bonded
ο
with morpholine moiety takes place up to 594 C, with 29.71% TG weight loss, ascribed to complete
ο
ligand pyrolysis and represented by a strong DTG peak at (Tmax.= 529 C). The thermal decomposition
process ends with the formation of CoO as a final product [16, 38, 46].
Insert Table 6 and its caption here
Insert Scheme 4 and its caption here
[
Cu(HL) Br(H O)].Br.6H O complex (5) is utilized as a model for the decomposition mechanism
2 2 2
for Cu(II); Zn(II), Cd(II) complexes (4, 5; 9, 10). The TG pattern of Cu(II) complex (5) reveals that the
ο
partial dehydration process takes place up to 209 C and associates with 7.29% TG weight loss (DTG
ο
peak at Tmax. = 45 C). The decomposition stage is represented by two successive steps. The first one
includes the removal of rest water (3.25 mole), debromination (coordinated and ionic) and two mole of
1
2

ACCEPTED MANUSCRIPT
ο
morpholine moiety. This step is compatible with 43.29% TG weight loss up to 563 C (DTG peak at
ο
Tmax. = 270 C) (Table 6). The removal of ionic bromide along with first decomposition step signifies
the hydrogen bonding between ionic bromide and lattice water molecules [44]. However, the second
ο
step displays 42.56% TG weight loss up to 891 C, ascribed to complete ligand pyrolysis. The thermal
decomposition reaction leads to the formation of copper metal (6.86%) as a final residue [47].
The data show that all metal complexes have higher thermal stability than that of the free ligand.
The higher thermal stability of Ni(II) complex (2) is due to its smaller ionic radius, in addition to the
steric hindrance in Cu(II); Zn(II), Cd(II) complexes (4, 5; 9, 10) [16, 41]. Also, Zn(II) complex (8)
shows higher thermal stability than Zn(II) and Cd(II) complexes (9, 10), due to the steric hindrance
caused by the number of the ligand molecules around the central metal ions [41]. The activation energy
of the dehydration step of Co(II), Ni(II) and Cu(II) complexes (1-3) is 173.29, 181.90 and 163.90 KJ
-1
mol , respectively, with a second order reaction (Table 7). Moreover, the E* of the first decomposition
step of those complexes is in the order; (2) > (1) > (3), proceeding via a first order reaction (Table 7)
and consistent with the thermal stability order of those complexes (Table 6). Also, the activation energy
and the order of reaction for the dehydration and/or desolvation process of Zn(II) and Cd(II) complexes
-1
-1
(
9, 10) are (125.61 KJ mol , 2.07) and (63.79 KJ mol , 1.60), respectively (Table 7). Meanwhile, the
-1
E* and n of the first decomposition step for these complexes are (249.92 KJ mol , 1.83) and (233.40
-1
KJ mol , 1.51) for complexes (9, 10), respectively (Table 7). These data are compatible with the
thermal stability order for these complexes; (9) > (10) (Table 6).
Insert Table 7 and its caption here
3
.7. Electronic spin resonance spectral studies of the thiosemicarbazone-copper(II) complexes
The ESR spectra of the solid Cu(II) complexes (3–7) measured on X–band frequency 9.714 GHz
at room temperature are illustrated in Table (8). The ESR spectra of these complexes show two well
resolved signals; gǁǁ = (2.161–2.275) and g
┴
= (2.028–2.068) ranges (Fig. 5). The spectra show that g׀׀ >
1
g┴ > 2.0023, pointing to an axial symmetry with (dx2-y2) ground state [16, 38, 48] and characteristic for
1
3

ACCEPTED MANUSCRIPT
the tetragonal distorted Cu(II) complexes [48]. The calculated gǁǁ values (Table 8) are less than 2.3,
confirmed with a distorted symmetry with covalence characters of metal–ligand bonds [42]. The
geometric parameter (G) measures the exchange interaction between Cu(II) centers in a polycrystalline
solid. The G value lies in range (4.15–8.16), excluding the exchange interaction between Cu(II) centers
[
48]. These data are compatible with magnetic moment values for Cu(II) complexes (3–7) (Table 5).
Insert Fig. 5 and its caption here
Insert Table 8 and its caption here
3
3
.8. Biological studies
.8.1. Molluscicidal activity
The results in Table (9) illustrate the molluscicidal activity data of metaldehyde,
thiosemicarbazone ligand (HL) and its Ni(II); Cu(II) complexes (2; 3, 5, 7) after 72 hours of treatment.
The data established that metaldehyde is more toxic than other compounds. On the other hand, the
thiosemicarbazone ligand is more toxic on Eobania vermiculata than its synthesized metal complexes,
attributed to the uncoordinated nitrogen and sulfur atoms of the free ligand. The higher toxicity of
Cu(II) ion is responsible for the higher molluscicidal activity of Cu(II) complexes (3, 5, 7) than Ni(II)
complex (2) [49]. Moreover, the data concluded that Eobania vermiculata is more susceptible to
metaldehyde and thiosemicarbazone ligand (HL) than Ni(II); Cu(II) complexes (2; 3, 5, 7) (Table 9).
Insert Table 9 and its caption here
3
.8.2. Biochemical results
The data obtained from the biochemical study of metaldehyde, thiosemicarbazone ligand and its
Ni(II); Cu(II) complexes (2; 3, 5, 7) (Fig. 6-8) established that metaldehyde inhibited the ALT activity
and increased the total protein and AST activity. Moreover, the thiosemicarbazone ligand and its tested
complexes possessed the same trend of metaldehyde towards the ALT activity (Table 10). While, the
combination between the tested compounds and metaldehyde led to a further decrease in the ALT
activity. However, the AST activity increased after treatment with the ligand and its complexes.
1
4

ACCEPTED MANUSCRIPT
Meanwhile, the mixture of metaldehyde with the tested compounds increased the AST activity more
than control. Also, the total proteins content increased after treatments. On the other hand, the TP
content of the tested snails was reduced after combination with metaldehyde (Table 10).
Insert Fig. 6 and its caption here
Insert Fig. 7 and its caption here
Insert Fig. 8 and its caption here
Insert Table 10 and its caption here
4
. Conclusion
The novel thiosemicarbazone ligand; (E)-N'-(1-(4-aminophenyl)ethylidene)morpholine-4-
carbothiohydrazide (HL) and its Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes were synthesized
and investigated by different analytical and spectral techniques. The obtained data established that the
ligand behaves as a neutral bidentate one and binds with metal ions via the azomethine nitrogen and
thione sulfur atoms (NS type). All metal complexes have octahedral geometry, except Cu(II)
complexes (3, 6, 7) which have a square planar one. The thermal decomposition data show that all
metal complexes have higher thermal stability than that of the free ligand. The ionic radii, number of
outer and inner sphere water molecules along with the steric hindrance caused by the number of the
ligand molecules around the central metal ions are important factors for illustrating the thermal stability
of metal complexes. The activity of metaldehyde, the ligand as well as its Ni(II); Cu(II) complexes (2;
3
, 5, 7) on the mucous gland of Eobania vermiculata was screened in vitro. The tested compounds have
nearly the same toxic effect of metaldehyde which increases the mucous secretion of the snails and
leads to death. The investigated compounds caused remarkable activity on some biochemical targets
(
ALT, AST, TP). These variations lead to serious metabolic and cellular damage. Thus, these
compounds can be used to combat the proliferation of Eobania vermiculata.
Acknowledgments
1
5

ACCEPTED MANUSCRIPT
The authors are grateful to Chemistry Department, Menoufia University and Harmful Animals
Department, Plant Protection Researches Institute for their constructive support.
References
[
[
[
1] T.A. Yousef, O.K. Alduaij, S.F. Ahmed, G.M. Abu El-Reash, O.A. El-Gammal, J. Mol. Struct.
1125 (2016) 788–799.
2] S.M. Kumar, K. Dhahagani, J. Rajesh, K. Anitha, G. Chakkaravarthi, N. Kanakachalam, M.
Marappan, G. Rajagopal, Polyhedron 85 (2015) 830–840.
3] S.M. Kumar, J. Rajesh, K. Anitha, K. Dhahagani, M. Marappan, N.I. Gandhi, G. Rajagopal,
Spectrochim. Acta A 142 (2015) 292–302.
[4] S. Datta, D.K. Seth, R.J. Butcher, S. Bhattacharya, Inorg. Chim. Acta 377 (2011) 120–128.
[5] P. Paul, P. Sengupta, S. Bhattacharya, J. Organomet. Chem. 724 (2013) 281–288.
[6] S. Kumar, N. Kumar, Int. J. Res. Pharm. Biomed. Sci. 4 (2013) 305–311.
[7] D. Kovala-Demertzi, M.A. Demertzis, J.R. Miller, C. Padadopoulou, C. Dodorou, G. Filousis, J.
Inorg. Biochem. 86 (2001) 555–563.
[8] M. Makavana, S. Sharma, J. Mol. Liq. 222 (2016) 535–548.
[9] P. Ghosh, M.J. Deka, A.K. Saikia, Tetrahedron 72 (2016) 690–698.
[10] J.D. Raja, S. Jeyaveeramadhavi, C. Vedhi, M. Sankarganesh, M. Vadivel, J. Chem. Pharm. Res.
7
(2015) 15–22.
[11] E.H. Eshra, Ann. Agric. Sci. 59 (2014) 281–284.
[
12] M.A. Radwan, A.E. Essawy, N.E. Abdelmeguied, S.S. Hamed, A.E. Ahmed, Pest. Biochem.
Physiol. 90 (2008) 154–167.
[13] J. Bassett, R.C. Denney, G.H. Jeffery, J. Mendham, Vogel’s Textbook of Quantitative Inorganic
th
Analysis Including Elementary Instrumental Analysis, 4 ed., Longman Group, London, (1978).
[14] J. Lewis, R.G. Wilkins, Modern Coordination Chemistry, Interscience, New York (1960) p.
1
6

ACCEPTED MANUSCRIPT
403.
[15] J.P. Scovill, Phosphorus, Sulfur Silicon Relat. Elem. 60 (1991) 15–19.
[16] S.A. AbouEl-Enein, S.M. Emam, M.W. Polis, E.M. Emara, J. Mol. Struct. 1099 (2015) 567–
5
78.
17] D.S. Young; Effect of Drugs on Clinical Laboratory Tests, 4 ed AACC Press Washington
1995) p. 1472.
18] D.S. Young; Effect of Disease on Clinical Laboratory Tests, 4 ed AACC Press Washington 48
2001) 682–683.
th
[
[
(
th
(
rd
[
19] D.J. Finney; Probit Analysis, 3 ed., Cambridge University Press, London (1971) p. 318.
20] R.G.D. Steel, J.H. Torrie, Principle and Procedure of Statistics. A Biometrical Approach, 2
ed., McGraw-Hill Book Company, New York, USA, 1981.
nd
[
[
[
[
21] A.M. Khedr, F.A. Saad, Turk. J. Chem. 39 (2015) 267–280.
22] S. Saikat, N.S. Kumar, C.A. Prasun, D. Kamalendu, Ind. J. Sci. 12 (2015) 17–24.
23] S.I. Al-Resayes, M. Shakir, A. Abbasi, Kr.M.Y. Amin, A. Lateef, Spectrochim. Acta A 93
2012) 86–94.
(
[
24] M.S. Refat, H.K. Ibrahim, S.Z.A. Sowellim, M.H. Soliman, E.M. Saeed, J. Inorg. Organomet.
Polym. 19 (2009) 521–531.
[25] (a) S.A. Patil, S.N. Unki, A.D. Kulkarni, V.H. Naik, P.S. Badami, Spectrochim. Acta A 79
(2011) 1128–1136;
(b) V. Marković, M.D. Joksović, S. Marković, I. Jakovljevic, J. Mol. Struct. 1058 (2014) 291–
297.
[26] P. Tyagi, S. Chandra, B.S. Saraswat, Spectrochim. Acta A 134 (2015) 200–209.
[27] S. Vinayaditya, A. Ameeta, M. Vikash, R. Ramsneh, A. Savita, Int. J. Res. Pharm. Sci. 1 (2011)
125–146.
1
7

ACCEPTED MANUSCRIPT
[
28] K. Ahmet. T. Esref, G. Bahattin, Y. Ismail, Chin. J. Chem. 24 (2006) 1599–1604.
29] K. Nomiya, K. Sekino, M. Ishikawa, A. Honda, M. Yokoyama, N.C. Kasuga, H. Yokoyama, S.
Nakano, K. Onodera, J. Inorg. Biochem. 98 (2004) 601–615.
[
[30] (a) T.V. Koksharova, Russ. J. Gen. Chem. 85 (2015) 111–115;
(
b) M.S. Masoud, M.A. EI-Dessouky, F.A. Aly, S.A. AbouEl-Enein, Transition Met. Chem. 15
1990) 443–448.
(
[
[
[
[
31] A.M. Hammam, M.A. EL-Gahami, Z.A. Khafagi, M.S. AL-Salimi, S.A. Ibrahim, J. Mater.
Environ. Sci. 6 (2015) 1596–1605.
32] N.A. Mazlan, T.B.S.A. Ravoof, E.R.T. Tiekink, M.I.M. Tahir, A. Veerakumarasivam, K.A.
Crouse, Transition Met. Chem. 39 (2014) 633–639.
33] H.B. Shawish, M. Paydar, C.Y. Looi, Y.L. Wong, E. Movahed, S.N. Abdul Halim, W.F. Wong,
M. Mustafa, M.J. Maah, Transition Met. Chem. 39 (2014) 81–94.
34] Y.S. Mary, C.Y. Panicker, M. Sapnakumari, B. Narayana, B.K. Sarojini, A.A. Al-Saadi, C.V.
Alsenoy, J.A. War, H.K. Fun, Spectrochim. Acta A 138 (2015) 529–538.
[
[
[
35] S. Chandra, S. Bargujar, R. Nirwal, N. Yadav, Spectrochim. Acta A 106 (2013) 91–98.
36] O.B. Ibrahim, Adv. Appl. Sci. Res. 3 (2012) 3522–3539.
37] Z.K. Genc, S. Tekin, S. Sandal, M. Sekerci, M. Genc, Res. Chem. Intermed. 41 (2015) 4477–
4488.
[
38] S.M. Emam, S.A. AbouEl-Enein, E.M. Emara, J. Therm. Anal. Calorim. 127 (2017) 1611–1630.
39] (a) E. Pahontu, F. Julea, T. Rosu, V. Purcarea, Y. Chumakov, P. Petrenco, A. Gulea, J. Cell.
Mol. Med. 19 (2015) 865–878;
[
(b) N.M. El Metwally, R. Arafa, U. El-Ayaan, J. Therm. Anal. Calorim. 115 (2014) 2357–2367.
[
40] S.M. Emam, A.S. El-Table, H.M. Ahmed, E.A. Emad, Arab. J. Chem. (2014) In Press.
41] S.M. Emam, I.E. El-Sayed, N. Nassar, Spectrochim. Acta A 138 (2015) 942–953.
[
1
8

ACCEPTED MANUSCRIPT
[
[
[
42] O.P. Gupta, A. Kumar, J. Chem. Chemic. Sci. 5 (2015) 69–78.
43] S.A. AbouEl-Enein, J. Therm. Anal. Calorim. 91 (2008) 929–936.
44] L.S. Vojinović-Ješić, M.V. Rodić, B.B. Holló, S.A. Ivković, V.M. Leovac, K.M. Szécsényi, J.
Therm. Anal. Calorim. 123 (2016) 2069–2079.
[
[
[
45] Y.K. Abdel-Monem, S.M. Emam, H.M.Y. Okda, J. Mater. Sci. Mater. Electron. 28 (2017)
2
923–2934.
46] Y.K. Abdel-Monem, S.A. Abou El-Enein, M.M. El-Sheikh-Amer, J. Mol. Struct. 1127 (2017)
86–396.
3
47] L.H. Abdel-Rahman, A.M. Abu-Dief, M. Ismael, M.A.A. Mohamed, N.A. Hashem, J. Mol.
Struct. 1103 (2016) 232–244.
[
48] M. Tyagi, S. Chandra, P. Tyagi, Spectrochim. Acta A 117 (2014) 1–8.
49] A. Abdul-Ghani, A. Abu-Hijleh, M. Qazzaz, Biol. Trace Elem. Res. 101 (2004) 87–95.
[
1
9

ACCEPTED MANUSCRIPT
Table 1
Analytical and physical data of the thiosemicarbazone ligand (HL) and its metal complexes
No Compound
F.W.
Elemental analyses Found/(Calcd.)%
M.P.
Ʌ
a
ο
-1
2
-1
Color
278.38
C
H
N
S
X
ــــ
M
ــــ
( C) ꢀ cm mol
HL
55.67
6.67
19.95
11.61
131
189
223
184
190
209
212
219
187
174
165
ــــ
23
76
58
112
57
6
C
13
H
18
N
4
SO
Yellow
(56.09)
31.28
(6.52) (20.13) (11.52)
5.77 11.88 7.11
ــــ
ــــ
1
2
3
4
5
6
7
8
9
[Co(HL)Cl (H O) ].2.75H O
2
2
2
2
493.88
14.73
12.69
C H N SO5.75CoCl2
Brown
(31.62)
30.17
(5.61) (11.34) (6.49) (14.38) (11.93)
5.57 10.79 6.27 13.88 11.64
(5.95) (10.67) (6.09) (13.52) (11.18)
5.59 11.97 6.91 15.91 14.15
(5.06) (12.23) (7.00) (15.50) (13.88)
13
27.5
4
[Ni(HL)Cl(H
C H N SO NiCl
2
2
O)
3
].Cl.3.5H
2
O
525.12
Yellowish brown
457.86
(29.73)
34.48
13
31
4
7.5
[Cu(HL)Cl(H O)].Cl.1.5H O
2
2
C H N SO CuCl
2
Green
(34.09)
37.41
13
23
4
3.5
[Cu(HL)
2
(H
2
O)
2
].Cl
2
.6H
2
O
835.26
5.82
(6.27) (13.41) (7.68) (8.50)
5.81 11.98 7.03 17.21
13.55
8.04
8.14
7.77
(7.61)
7.35
C H N S O CuCl
Yellowish green
906.24
(37.38)
34.11
26
52
8
2
10
2
[Cu(HL) Br(H O)].Br.6H O
2
2
2
C
26
H
50
N
8
S
2
O
9
CuBr
2
Light green
507.97
(34.46)
43.77
(5.56) (12.37) (7.08) (17.63) (7.01)
[Cu(HL)(CH COO) ].0.75EtOH.0.75H O
5.58
(5.95) (11.03) (6.30)
3.84 12.51 5.79
(4.25) (12.11) (6.91)
4.99 12.09 6.81
12.03
6.58
ــــ
ــــ
12.46
(12.50)
13.62
3
2
2
C18.5H N SO Cu
Dark green
462.83
(43.74)
33.46
30
4
6.5
[Cu(HL)(ClO )(OH)].0.25H O
ــــ
22
6
4
2
C
13
H
19.5
N
4
SO6.25CuCl
Brown
(33.74)
33.77
ــــ
(13.72)
13.58
[Zn(HL)Cl (H O) ].H O
468.84
15.73
2
2
2
2
C H N SO ZnCl
2
Yellow
(33.30)
43.81
(5.16) (11.95) (6.84) (15.14) (13.95)
13
24
4
4
[Zn(HL) Cl ].1.5H O
720.19
5.40
(5.46) (15.56) (8.90) (9.86)
6.43 11.33 6.91 6.61
15.13
8.25
9.13
9.21
(9.08)
10.82
7
2
2
2
C
26
H
39
N
8
S
2
O
3.5ZnCl
2
Yellow
(43.36)
41.07
1
0
[Cd(HL) Cl ].4EtOH.4H O
2
2
2
996.51
3
C H N S O CdCl
2
Yellow
(40.98)
(6.88) (11.24) (6.44) (7.12) (11.28)
34
68
8
2
10
a
:
X = Cl or Br
1

ACCEPTED MANUSCRIPT
Table 2
1
H NMR spectra of the ligand and its complexes (8-10)
Ligand
HL)
[Zn(HL)Cl (H O) ].H O
[Zn(HL) Cl ].1.5H O
[Cd(HL) Cl ].4EtOH.4H O
Assignment
2
2
2
2
2
2
2
2
2
2
(
complex (8)
complex (9)
complex (10)
1
0.47
.87
.53–7.99
–
10.39
–
–NH (Z- form)
–NH (E-form)
9
10.11
9.91
9.92
6
6.52–7.93
5.54
6.44–7.93
5.59
6.52–7.99
5.49
aromatic ring protons
5
.44
-
–NH protons
2
3.84
3.83
3.89
solvents protons
3
2
.07–3.82
.15–2.48
3.07–3.76
2.14–2.47
3.07–3.82
2.18–2.47
3.07–3.75
2.15–2.47
–CH protons
2
3
–CH protons
2

ACCEPTED MANUSCRIPT
Table 3
Infrared spectral bands (cm ) of the thiosemicarbazone ligand and its metal complexes
-1
No Compound
ν(OH) +
ν(C=N)
Thioamide bands
ν(NH
2
)/ν(NH) + δ(NH
2
)
υ(N–NH) γ(C=S)
1036(s) 505(m)
γ(NH)
ν(M-O)
ν(M-N)
I
II
III
IV
HL
3445(s,b)
1620(s)
1533(s)
1291(s)
1223(s)
904(m)
694(m)
ـــ
ــــ
3
3
398(m)
375(m)
3
236(s)
1
2
3
4
5
6
[Co(HL)Cl
[Ni(HL)Cl(H
[Cu(HL)Cl(H
2
(H
O)
O)].Cl.1.5H
O) ].Cl .6H
O)].Br.6H
2
O)
2
].2.75H
2
O
3424(s,b)
3419(s,b)
3445(s,b)
3442(s)
1618(s)
1633(s)
1573(w)
1573(m)
1546(m)
1276(s)
1276(s)
1271(s)
1232(s)
887(s)
1031(m) 546(w)
1025(s) 546(w)
1239(w) 881(m) 1033(w) 532(w)
690(w)
680(m)
679(w)
486(w)
483(w)
491(w)
473(w)
456(w)
425(w)
469(w)
446(w)
2
3
].Cl.3.5H
2
O
1248(m) 891(m)
2
2
O
1601(m)
[Cu(HL)
[Cu(HL)
(H
O
1607(m) 1550(s,sp) 1275(m) 1240(m) 883(m) 1028(m) 508(w) 687(vw)
2
2
2
2
2
Br(H
O
3450(s,b)
3445(s,b)
1613(s)
1613(s)
1550(s)
1275(m) 1240(m) 882(m) 1027(m) 510(w) 702(vw)
483(vw) 477(w)
492(vw) 470(w)
2
2
2
[Cu(HL)(CH
COO)
].0.75EtOH.0.75H
O
1552(w)
1272(m)
1229(s)
884(s)
1033(w) 528(w)
792(w)
3
2
2
3
407(w)
7
8
9
[Cu(HL)(ClO
[Zn(HL)Cl (H
[Zn(HL) Cl ].1.5H
[Cd(HL) Cl ].4EtOH.4H O
2
4
)(OH)].0.25H
2
O
3443(s,b)
3446(m,b)
3401(s,b)
3473(w)
1606(s)
1612(m)
1623(s)
1622(s)
1543(w)
1519(s)
1270(s)
1231(s)
883(m) 1045(w) 530(w) 699(vw)
496(vw) 453(w)
487(vw) 437(w)
O) ].H
O
1275(m) 1235(m) 871(m) 1031(w) 513(w)
694(w)
693(w)
683(w)
2
2
2
2
O
1528(w)
1594(s)
1281(w)
1271(s)
1231(w)
1231(s)
880(s)
883(s)
1047(s)
508(w)
470(w)
481(vw) 424(w)
439(w)
2
2
2
1
0
2
2
1030(m) 513(m)
3
446(w)
1546(vw)
vw: very weak, w: weak, m: medium, s: strong, b: broad, sh: shoulder, sp: splitted.
3

ACCEPTED MANUSCRIPT
Table 4
Fundamental bond lengths for the ligand (HL)
Atom Bond Atom Bond length (Å) Atom Bond Atom Bond length (Å)
C(9)
C(10)
C(11)
C(12)
C(13)
C(6)
N(14)
N(1)
C(7)
C(8)
C(9)
C(10)
C(11)
C(8)
C(8)
C(11)
C(6)
1.3948
1.3949
1.3948
1.3948
1.3948
1.3370
1.2660
1.2600
1.4970
N(2)
C(3)
N(5)
C(15)
C(19)
C(16)
O(17)
C(18)
S(4)
N(1)
N(2)
C(3)
N(5)
N(5)
C(15)
C(16)
C(19)
C(3)
1.3520
1.3690
1.3690
1.4756
1.4756
1.5364
1.4333
1.5364
1.5760
C(6)
4

ACCEPTED MANUSCRIPT
Table 5
Electronic spectral data and magnetic moment values of the ligand and its metal complexes
No. Compound
Electronic spectral bands (nm)
Assignment
µeff.
B.M.)*
_
(
HL
320,367
n-
π
*
*
265
π-π
4
4
1
2
3
4
5
6
7
[Co(HL)Cl
2
(H
2
O)
2
].2.75H
2
O
687
T
1g(F)
T (F)
→
→
A
T (P)
2g
2g(P)
5.07
3.56
1.82
1.70
1.75
1.86
1.81
4
4
5
4
86
34
1
g
LMCT
Intraligand transition
2
2
2
2
2
3
2
69,334
681
3
3
[Ni(HL)Cl(H
O)
2
].Cl.3.5H
3
O
2
A
2g (F)
→
→
T1g(F)
3
3
5
4
18
36
A (F)
T (P)
1g
2
g
LMCT
Intraligand transition
31,334
688
2
2
[Cu(HL)Cl(H
O)].Cl.1.5H
2
O
2
B → E
1g g
2
2
5
4
61
32
B1g
→ A1g
LMCT
Intraligand transition
67,332
671
2
2
[Cu(HL)
[Cu(HL)
(H
O)
2
].Cl
2
.6H
2
O
2
B
→
B
2
1g
2g
2
2
5
4
64
24
B1g → Eg
LMCT
Intraligand transition
43,322
682
2
2
Br(H
2
O)].Br.6H
2
O
B
→
B
2
1g
2g
2
2
5
4
44
38
B1g → Eg
LMCT
Intraligand transition
76,343
684
2
2
[Cu(HL)(CH
COO)
3
].0.75EtOH.0.75H
2
O
2
B
→
→
E
1g
g
2
2
5
4
58
12
B
1g
A
1g
LMCT
Intraligand transition
00,343
679
2
2
[Cu(HL)(ClO
)(OH)].0.25H
O
B
→
→
E
4
2
1g
g
2
2
5
4
26
20
B
1g
A
1g
LMCT
Intraligand transition
71,339
8
[Zn(HL)Cl
[Zn(HL) Cl
[Cd(HL) Cl
: (per metal ion)
2
(H
].1.5H
].4EtOH.4H
2
O)
2
].H
2
O
448
41,349
467
73,320
440
71,345
LMCT
Intraligand transition
LMCT
Diamagnetic
Diamagnetic
Diamagnetic
2
2
2
9
2
2
2
O
Intraligand transition
10
2
2
2
O
LMCT
Intraligand transition
*
5

ACCEPTED MANUSCRIPT
Table 6. Thermal decomposition of (HL) ligand and its metal complexes
No. Compound
TG range DTG peak
Mass Loss %
Found Calcd.
Assignment
stable
T
S
ο
ο
ο
(
C)
( C)
( C)
HL
25-133
33-505
-
-
-
133
g
d
1
169
01
07
55.47
55.57 loss of C
5
H
7
N
3
SO
c
2
3
g
I
d
5
05-712
611
42.20
0.57
41.78 loss of C H N
7.75 11
r
At 712
1.06
10.03 loss of 2.75 mole of H
21.67 loss of Cl and 2 mole of H O
0.25C
f
a
1
2
3
[Co(HL)Cl (H O) ].2.75H O
19-192
37
10.09
21.06
23.91
29.71
15.23
11.41
24.43
22.27
27.08
14.81
13.33
11.77
25.73
33.78
2
O
192
226
188
2
2
2
2
c
d
1
2
4
92-262
62-431
31-594
216
305
2
2
g
d
23.92 loss of C
29.20 loss of C H N S
15.17 CoO
11.15 loss of 3.25 mole of H O
2
24.67 loss of Cl and 3.25 mole of H O
22.50 loss of C
27.46 loss of C H N S
14.22 NiO
13.65 loss of 1.5 mole of H
11.69 loss of one mole of H O and 0.5Cl
8 8
H N
c
d
529
5
10
3
r
At 594
e
a
[Ni(HL)Cl(H O) ].Cl.3.5H O
2
3
2
19-226
51
c
d
2
26-289
89-498
98-899
255
2
2
f
d
2
4
310
8 8
H N
c
d
512
5
10
3
r
At 899
e
a
[Cu(HL)Cl(H O)].Cl.1.5H O
2
2
18-188
39
2
O and 0.5Cl
2
e
d
1
88-259
59-503
03-899
226
2 2
e
d
2
5
312
25.80 loss of C
33.67 loss of C H N SO
8 8
H N
c
d
603
4
.5 10
3
g
8
8
22
74
g
r
At 899
15.39
10.94
33.62
15.19 Cu + 0.5C
10.78 loss of 5 mole of H
33.67 loss of Cl , 2 mole of H O and 2 mole of C H NO
e
a
4
[Cu(HL) (H O) ].Cl .6H O
18-192
38
2
O
192
2
2
2
2
2
c
d
1
92-391
230
2
2
4
9
e
3
31
c
d
3
91-899
582
42.03
42.43 loss of C15.5H N S
6 2
20
g
6
38
r
At 899
13.41
7.29
13.12 CuO + 2.5C
7.46 loss of 3.75 mole of H
f
a
5
6
[Cu(HL) Br(H O)].Br.6H O
28-209
45
2
O
209
215
2
2
2
c
d
2
5
09-563
63-891
270
43.29
42.56
43.32 loss of Br , 3.25 mole of H O and 2 mole of C H NO
42.21 loss of C H N S
2
2
4
9
I
d
714
1
8
18
6 2
g
872
r
At 891
6.86
9.56
7.01
9.46
Cu
f
a+b
[Cu(HL)(CH COO) ].0.75EtOH.0.75H O
25-215
43
2
loss of 0.75 mole of EtOH and 0.75 mole of H O
3
2
2
g
1
97
c
d
2
3
4
15-311
11-454
54-647
243
23.15
23.16
25.19
23.24 loss of 2CH COO
23.26 loss of C H N
25.43 loss of C3.75H N S
3
h
d
468
-
8
8
d
10
3
r
At 647
18.94
18.61 CuO + 1.25C
a
b
d
c
e
f
g
h
I
r
:
Dehydration, : Desolvation, : Decomposition, : strong, : medium, : weak, : very weak, : broad, : broad strong, : final residue
6

ACCEPTED MANUSCRIPT
Table 6. Continued
No. Compound
TG range
DTG peak
Mass Loss % Assignment
Found Calcd.
T
( C)
192
S
ο
ο
ο
(
C)
( C)
f
a
8
[Zn(HL)Cl (H O) ].H O
30-192
46
2.34
24.71
25.15
32.97
14.83
1.92
loss of 0.5 mole of H
2
O
2
2
2
2
c
d
1
3
5
92-338
38-571
71-899
258
24.75 loss of 2.5 mole of H
25.20 loss of C H N
8 8
32.89 loss of C H N SO
3
15.23 Zn + 0.5C
2
O and Cl
2
e
d
5
6
08
h
d
51
4.5 10
r
At 899
f
a
9
[Zn(HL) Cl ].1.5H O
21-176
39
3.82
34.13
51.57
3.75
loss of 1.5 mole of H
2
O
176
166
2
2
2
I
d
1
3
76-397
97-899
222
34.05 loss of Cl
and 2 mole of C H NO
2 4 9
f
d
4
5
93
51.86 loss of C17.25H N S
18 6 2
c
89
r
At 899
10.48
10.33 Zn + 0.75C
1.16 loss of 0.25 mole of EtOH
49.17 loss of Cl , 3.75 mole of EtOH, 4 mole of H O and 2 mole of C H NO
g
b
1
0
[Cd(HL) Cl ].4EtOH.4H O
29-166
51
1.45
49.21
2
2
2
c
d
1
66-607
236
2
2
4
9
f
4
08
h
d
6
07-899
731
At 899
38.52
38.39 loss of C H N S
6 2
1
8
18
r
10.82
11.28 Cd
a
b
d
c
e
f
g
h
I
r
:
Dehydration, : Desolvation, : Decomposition, : strong, : medium, : weak, : very weak, : broad, : broad strong, : final residue
7

ACCEPTED MANUSCRIPT
Table 7. Kinetic parameters of the thermal decomposition of the thiosemicarbazone ligand (HL) and its metal complexes
-
1
No. Compound
Stage
No.
I
Temperature
range ( C)
133-505
DTG peak
n
ꢁE*/
KJmol
182.47
31.02
ꢁH*/
KJmol
179.90
28.59
A/s
-ꢁS*/
ꢁG*/
-1
ο
ο
-1
-1
-1 -1
(
C)
KJmol K
0.0291
0.0458
0.0222
0.0348
0.0668
0.0706
0.0714
0.0242
0.0669
0.0707
0.0706
0.0737
0.0666
0.0707
0.0725
0.0392
0.0758
0.0764
0.0186
0.0707
0.0721
0.0764
0.0747
0.0669
0.0721
0.0783
0.0787
0.0666
0.0688
0.0706
0.0756
0.0245
0.0719
0.0745
0.0276
0.0261
0.0329
0.0322
0.0336
0.2141
0.2105
0.2104
0.2213
KJmol
g
c
g
I
HL
169
2
3
611
2.22
1.92
0.56
1.15
1.76
1.31
1.44
1.46
1.53
1.28
1.65
1.78
1.83
1.35
0.87
0.57
1.17
1.24
2.85
1.63
1.07
0.57
1.40
2.05
1.53
0.54
0.51
2.18
1.82
1.70
1.44
1.78
1.69
1.22
1.44
2.07
1.83
1.24
1.38
1.60
1.51
1.16
1.13
262.30
37.88
188.89
41.96
01
07
638.17
387.35
173.29
230.34
885.52
1011.54
181.90
394.24
896.47
769.72
163.90
213.74
188.41
229.38
1968.71
1707.35
222.49
263.66
339.48
134.80
1105.56
151.84
140.35
75.82
197.22
179.60
717.25
350.97
73.91
154.90
124.07
352.31
943.57
125.61
249.92
392.13
422.58
63.79
635.62
384.97
134.87
227.87
882.82
1009.01
179.36
391.73
894.03
767.17
161.46
241.15
185.74
225.22
1965.00
1704.89
220.05
261.07
334.46
131.03
1103.17
149.43
137.57
70.91
194.27
177.31
714.89
348.68
71.48
152.50
121.25
349.87
940.60
123.19
147.27
389.24
419.81
61.34
786.50
263.50
298.98
269.90
1159.74
858.64
391.75
504.07
1203.38
645.27
363.58
313.13
195.50
154.49
1244.36
988.02
535.73
334.03
357.12
91.23
642.44
398.16
154.30
248.85
894.36
1021.93
199.75
413.07
914.79
789.80
181.04
263.13
209.01
244.82
1998.82
1727.50
225.49
283.06
358.62
165.63
1124.61
168.83
161.65
117.18
222.21
196.69
739.92
369.92
104.01
159.57
145.62
371.70
950.45
130.79
157.77
400.45
431.00
124.50
302.75
483.09
352.85
II
I
II
III
IV
I
505-712
19-192
192-262
262-431
431-594
19-226
226-289
289-498
498-899
18-188
188-259
259-503
503-899
f
1
2
3
[Co(HL)Cl (H O) ].2.75H O
37
2
2
2
2
c
216
305
529
51
255
310
512
39
226
312
603
g
c
e
[Ni(HL)Cl(H O) ].Cl.3.5H O
2
3
2
c
II
f
III
IV
I
II
III
IV
c
e
[Cu(HL)Cl(H O)].Cl.1.5H O
2
2
e
e
c
g
g
8
8
38
22
74
e
4
[Cu(HL) (H O) ].Cl .6H O
I
II
18-192
192-391
2
2
2
2
2
c
e
c
g
230
31
582
38
3
III
391-899
6
805.51
322.35
155.43
44.02
f
5
6
8
9
[Cu(HL) Br(H O)].Br.6H O
I
II
III
28-209
209-563
563-891
45
270
714
8
43
1
243
468
46
258
508
651
39
222
493
5
51
236
2
2
2
c
I
g
72
99.67
f
[Cu(HL)(CH COO) ].0.75EtOH.0.75H O
I
25-215
403.04
1281..31
451.47
57.72
3
2
2
g
c
97
II
III
I
215-311
311-647
30-192
192-338
338-571
571-899
21-176
h
f
[Zn(HL)Cl (H O) ].H O
330.57
143.16
273.83
659.27
266.69
183.85
313.65
297.58
120.15
289.80
390.96
157.40
2
2
2
2
c
e
II
III
IV
I
II
III
h
f
[Zn(HL) Cl ].1.5H O
2
2
2
I
176-397
397-899
f
c
89
g
1
0
[Cd(HL) Cl ].4EtOH.4H O
I
II
29-166
166-607
2
2
2
c
f
233.40
420.85
269.78
230.55
418.29
266.54
4
08
h
III
607-899
731
c
e
f
g
h
I
:
strong, : medium, : weak, : very weak, : broad, : broad strong
8

ACCEPTED MANUSCRIPT
Table 8
ESR parameters of the thiosemicarbazone-copper(II) complexes (3-7)
No. Complex g׀׀ g┴ *gav. **G
3
4
5
6
7
[Cu(HL)Cl(H
2
O)].Cl.1.5H
O) ].Cl .6H
O)].Br.6H
2
O
2.254 2.061 2.126 4.29
2.275 2.068 2.137 4.15
2.233 2.031 2.098 8.04
O 2.161 2.032 2.075 5.34
2.212 2.028 2.089 8.16
[Cu(HL)
2
2
(H
2
2
2
2
O
[Cu(HL)
Br(H
O
2
2
[Cu(HL)(CH
3
2 2
COO) ].0.75EtOH.0.75H
[Cu(HL)(ClO
)(OH)].0.25H O
2
4
av // ׀׀ ┴
⊥
*: g = (2g + g )/3 and **: G = (g – 2.0023) / ( g – 2.0023)
9

ACCEPTED MANUSCRIPT
Table 9
Molluscicidal activity data of the tested compounds
No. Compound
Concentration Corrected Mortality LC50 Slope ± S.E.
(ppm)
(%)
HL
300
66.63
58.29
49.95
49.95
96.66
94.99
74.97
49.95
58.29
41.61
41.61
8.24
66.63
49.95
24.92
16.58
66.63
49.95
24.92
8.24
67.25 0.54 ± 0.21
50.91 2.51 ± 0.30
218.66 1.66 ± 0.24
193.33 1.85 ± 0.24
197.50 2.32 ± 0.26
204.21 1.99 ± 0.25
2
1
00
00
5
0
Metaldehyde
300
2
1
00
00
5
0
2
3
5
7
[Ni(HL)Cl(H
2
O)
3
].Cl.3.5H
2
O
300
2
1
00
00
5
0
[Cu(HL)Cl(H
O)].Cl.1.5H
O
300
2
2
2
1
00
00
5
0
[Cu(HL)
Br(H
O)].Br.6H
O
300
2
2
2
2
1
00
00
5
0
[Cu(HL)(ClO
)(OH)].0.25H
O
300
66.63
49.95
16.58
16.58
4
2
2
1
00
00
5
0
1
0