Synthesis for novel VO(II)- triazole complexes; spectral, analytical characterization and catalytic usage for biodiesel synthesis from waste oil

Article abstract of DOI:10.1016/j.molstruc.2019.04.018

Novel mono-nuclear VO(II)-traizoles complexes have been synthesized and fully characterized by all possible tools(analytical, spectral and conformational). The neutral tri-dentate mode, was the suggested bonding feature based on comparative IR spectra. Th

Full text of DOI:10.1016/j.molstruc.2019.04.018

Accepted Manuscript
Synthesis for novel VO(II)- triazole complexes; spectral, analytical characterization
and catalytic usage for biodiesel synthesis from waste oil
Nashwa El-Metwaly, Thoraya A. Farghaly, Ismail Althagafi, Marwa G. Elghalban
PII:
S0022-2860(19)30407-7
DOI:
https://doi.org/10.1016/j.molstruc.2019.04.018
MOLSTR 26390
Reference:
To appear in: Journal of Molecular Structure
Received Date: 10 February 2019
Revised Date: 2 April 2019
Accepted Date: 3 April 2019
Please cite this article as: N. El-Metwaly, T.A. Farghaly, I. Althagafi, M.G. Elghalban, Synthesis
for novel VO(II)- triazole complexes; spectral, analytical characterization and catalytic usage for
biodiesel synthesis from waste oil, Journal of Molecular Structure (2019), doi: https://doi.org/10.1016/
j.molstruc.2019.04.018.
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
Graphical Abstract
______________________________________________________________________________
Synthesis for novel VO(II)- triazole complexes; spectral, analytical
characterization and catalytic usage for biodiesel synthesis from waste oil
Nashwa El-Metwaly*
│
Thoraya A. Farghaly
│
Ismail Althagafi
│
Marwa G. Elghalban
Waste
Biodiesel
cooking oil
_____________________________________________________________________________________

ACCEPTED MANUSCRIPT
Synthesis for novel VO(II)- triazole complexes; spectral, analytical characterization
and catalytic usage for biodiesel synthesis from waste oil
Nashwa El-Metwalya,b*│Thoraya A. Farghalya,c│ Ismail Althagafia│ Marwa G. Elghalbana,b
a
Chemistry Department, College of Applied Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
bChemistry Department Faculty of Science, Mansoura University, Mansoura, Egypt
c Chemistry Department, Faculty of Science, Cairo University, Cairo, Egypt
ABSTRACT
Novel mono-nuclear VO(II)-traizoles complexes have been synthesized and fully characterized by all
possible tools(analytical, spectral and conformational). The neutral tri-dentate mode, was the suggested
bonding feature based on comparative IR spectra. The octahedral geometry, was suggested for all
complexes except for [VO(CATP)(H2O)] (SO4)(H2O)2 complex. ESR spectral data clarify, the ionic
feature of in plane σ- bonding as well as in plane π - bonding. XRD patterns display the amorphous
feature, as the main characteristic for most tested compounds. Two crystalline complexes, showed
crystallite-sizes located excellently in nanometer range. SEM images displayed rocky-shape surfaces
for all tested compounds, except for the two crystallite complexes. TGA curves displayed
discriminated thermal stability, among investigated complexes, which most of them appeared with
high thermal stability. Conformational indexes calculated predict the superiority features of
[VOSO4(CATB)]H2O complex. This study was strengthen by docking process, which orients to the
negligible inhibition role of most VO(II)-complexes against DNA (2hio). Another application pathway
was interested to synthesize biodiesel from waste oils. A chosen complex (VO(II)-CATB) was utilized
in heterogeneous-catalytic process. Moreover, its V2O5 oxide has been prepared from deliberate
calcinations process. The complex and its oxide have been used separately to prepare economic
compound (biodiesel) from waste oil. The two catalysts succeeded in isolating biodiesel, in particular
the complex which produced a perfect product in record time. Some physical characteristics were
estimated for synthesized biodiesel, which highly compatible with that reported in literature for other
undesirable biodiesel-synthesis processes.
Keywords: VO(II)-Traizole complexes, Biodiesel synthesis, Molecular Docking, DFT/B3LYP
*Corresponding author: Prof. Nashwa M. El-Metwaly
E- mail address: n_elmetwaly00@yahoo.com , Telephone No.: +966538553123
1. INTRODUCTION
1

ACCEPTED MANUSCRIPT
One of the challenges facing industry and many sectors in the world is the lack of energy
sources. Scientists around the world are searching for cheap and easy-to-access sources of energy. The
curtailment fossil fuel reserves and more rigorous environmental assizes have produced a global
concern in renewable energy sources. The alternative fuel, biodiesel, is generated from the trans-
esterification by alcohols of animal fats or vegetable oils [1]. The properties of biodiesel are similar to
those of petroleum-diesel and can be used in traditional diesel engines without amendment. Biodiesel
is less toxic, renewable and has minimal environmental effect compared to diesel extracted from
petroleum [2]. The limitation of the production of biodiesel is attributed to high costs of raw material,
vegetable oils [3]. Also, using the edible oils in the production of biodiesel will be affected on the
existing food market. So, the researches over the worldwide have focused on biodiesel production from
WCO(Waste Cooking Oil) as a third generation source which have a positive effect on the efficiency
of such fuel[4,5]. The tras-estrification with homogenous catalysts such as KOH and NaOH has some
advantages as low price and easy availability, but the catalyst cannot be reused. Furthermore, it gives
soaps when reacts with oil and acids, which reduces the percent yield of esters, make the detachment
difficult and also consume the catalyst and cannot be isolated from the reaction mixture. So, using
heterogeneous catalysts especially metal oxides is the suitable solution to these problems[6,7].On the
other hand, the discovery of vanadate-dependent enzymes and their significance in diverse biological
catalytic operations [8,9] has spurred research on the catalytic manifestations of vanadium (VOLx)
complexes. Several pattern vanadium complexes display catalytic activity towards different organic
conversions, also, VO(II)-nitrogen coordination plays a good role in catalysis of nitrophenol to
aminophenol[10,11].Triazoles and their Schiff's bases displayed outstanding pharmacological activities
as anticonvulsant, antimicrobial, antitumor, analgesic, and antidepressant[12]. From the previous work
reported, we intended to synthesize new VO(II)-traizole complexes. These complexes will be fully
characterized using all possible spectral, analytical and theoretical techniques. Two selected complexes
will be tested towards biodiesel synthesis from waste oil. Moreover, their oxides yielded from
calcinations will be used in this catalytic application after full description. This heterogeneous catalytic
process, will be compared versus referenced undesirable method, which mainly used a dangerous
catalyst (CaO). This study, aims to throw a shadow on a new distinguish catalyst used to synthesize
economic product from wastes by a safe process.
2. Methodology
2.1. The reagents
2

ACCEPTED MANUSCRIPT
All chemicals, reagents and solvents were purchased from Fluka, Merck and Sigma-Aldrich.
Also, used as it is without previous treatments. VOSO4.XH2O, trifluoroacetic acid, thiocarbohydrazide,
4-chlorobenzaldehyde,
2-bromo-4′-aminoacetophenone,
2-bromo-4′-methylacetophenone,
2-
bromoacetophenone, 2-bromo-4′-chloroacetophenone and 2-bromo-4′-bromoacetophenone, were the
compounds utilized in the synthesis for new compounds.
2.2. Preparations
2.2.1. Synthesis of triazole derivatives
A scientific preparation method for 4-amino-5-trifluoromethyl-4H-[1,2,4]triazole-3-thiol (3) was
reported in previous work[13].As; equi-moles from aqueous trifluoroacetic acid (1) (11.4g, 0.1 mol) and
thiocarbohydrazide (2) (10.6g, 0.1 mol) were mixed and refluxed along 5h, then cooled. The white
crystals obtained were isolated through filtration followed by washing with cold water and re-
crystallized from water to produced pure triazole compound 3. Conversion of triazole derivative 3 to 4-
((4-chlorobenzylidene)amino)-triazole-3-thiol derivative 4 carried out via the condensation of
aminotriazole thiol 3 (4.6g, 0.025 mol) with 4-chlorobenzaldehyde (3.5g, 0.025 mol) in glacial acetic
acid (20 mL) under conventional heating for 5 h followed by filtration for the formed precipitate and
crystallization from ethanol. New traizole compounds (6a-e, Scheme 1) were isolated from the reaction
of equi-moles (3.06g, 0.01 mol) from compound 4 and α-haloketone derivatives (5a-e) (2.12g (5a) or
2.13g (5b) or 1.98g (5c) or 2.31g (5d) or 2.76g (5e), 0.01 mol) . Each reaction mixture was refluxed in
dioxane (30 ml) in presence of 0.35 mL triethylamine a long 8-10 h (tested regularly by TLC (1:1,
ethylacetate : n-hexane). The solid precipitates were filtrated off and re-crystallized from proper solvent.
The best structural form for five derivatives was displayed (Fig. 1).
S
CF3COOH
H2NHN
H2O
NHNH2
+
1
2
N
N
N
N
Ar
F3C
ArCOCH2Br
5
S
F3C
N
N
SH
N
N
Cl
OHC
SH
O
N
N
F3C
Dioxane/Et3N
6
N
H2N
AcOH /
4
3
Cl
Cl
Ar
Compd. No.
Yield
78%
4-NH2C6H4
4-CH3C6H4
C6H5
6a
6b
6c
6d
6e
80%
75%
72%
70%
4-ClC6H4
4-BrC6H4
Scheme 1. Synthesis of ligands 6a-e
3

ACCEPTED MANUSCRIPT
F
F
N
F
N
S
(ACTA)
N
N
H
N
H
O
Cl
F
F
N
F
N
S
(ACTM)
N
N
CH3
O
Cl
F
F
N
F
N
(ACTP)
N
N
S
O
Cl
F
F
N
F
N
S
(ACTC)
N
N
Cl
O
Cl
F
F
N
F
N
S
(ACTB)
N
N
Br
O
Cl
Fig. 1. Optimized structures of traizole derivatives (6a-e; CATA-CATB)
2.2.2. Preparation of VO(II)-traizole complexes
4

ACCEPTED MANUSCRIPT
Novel colored VO(II)- traizole complexes were synthesized by mixing equi-molar weights.
Dissolving 2mmol from VOSO4.xH2O (neglecting hydrated water, 0.326g), then added to ethanolic
solutions of traizole derivatives (6a-e) as follow, 0.880, 0.878, 0.850, 0.919 and 1.01 g, sequentially.
All mixed solutions were refluxed for 4-7h. Dissolved 0.5 g sodium acetate (in bi-distilled water), was
added to adjust pH of each solution for precipitation. The colored precipitates were isolated after
filtration and washed by ethanol, diethyl ether and finally dried in vacuum desiccators.
2.3. Analysis techniques
The percentages of elements (carbon, hydrogen and nitrogen) were extracted by implementing
Perkin-Elmer 2400 CHN Elemental Analyzer. The metal and sulfur contents were evaluated using
standard analytical methods [14]. The conductance measurements (in DMSO) were recorded by
JENWAY model 4070 Conductance Bridge. KBr-IR and NMR spectra were scanned over JASCO FT-
IR-4100 spectrophotometer (400-4000 cm-1) and Burker (500MHz), respectively. The electronic
spectra and magnetic susceptibility were obtained through UV2 Unicam UV/Vis spectrophotometer (in
o
DMSO solvent) and Johnson Matthey Magnetic Susceptibility Balance at 25 C, respectively. Mass
spectra for two selected complexes were conducted at70 ev by using AEIMS 30 mass spectrometer
using 40°C/min, heating rate and the mass/ charge scanning range was 50-1000. EPR spectra were
o
given at 25 C by using Jeol JES-RE1X EPR spectrometer with DPPH standard (υ = 9.435 GHz).
TGA/DTG curves were extracted by Shimadzu Thermogravimetric Analyzer (20-900oC). The heating
o
rate was 10 C min-1 under nitrogen. XRD patterns were obtained (10˚<2θ <90˚ rang) on X-ray
diffractometer (GNR, APD2000PRO, Italy) with a graphite mono-chromator. The scanning rate is
0.03° min−1 by using Cu/Kα1 radiation. SEM images were displayed on Joel JSM-6390 equipment.
Molecular modeling and docking were executed by Gaussian09 and Autodock tools 4.2, respectively.
DNA degradation was achieved in molecular biology lab.
2.4. Computational studies
2.4.1. Kinetics
ꢀH, ꢀS and ꢀG were the thermodynamic parameters intended for computation over DTG
curves. The order (n) and energy of activation (E) were also calculated over chosen stages. Well
identified bordered, was the significant characteristic for chosen stages, which varied completely upon
investigated curves. Many researchers [15-23] had accomplished equations for calculating these
5

ACCEPTED MANUSCRIPT
parameters and discussing the advantages for such calculations in raising the knowledge about the
prepared compounds and orient for application. Coat-Redfern[17] and Horowitz-Metzger[22], among
the researchers interested in this point of research and developed equations for such purpose. These
equations were implemented to calculate thermodynamic parameters over definite stages in DTG
curves.
2.4.2. DFT/B3LYP method
The molecular optimization process, was performed by implementing Gaussian 09 program
[24]. All triazole derivatives and their VO(II) complexes, were treated by using DFT/B3LYP method at
suitable base set. Log and chk files were extracted and visualized upon Gauss-View program [25].All
atoms were numbered according to scientific scheme. Essential parameters were extracted from output
files, especially for EHOMO and ELOMO levels. Also, significant physical parameters were estimated by
using known relations [26, 27], as follow;
1- χ = -0.5 (ELUMO + EHOMO
)
2- ꢁ = - χ = 0.5 (ELUMO + EHOMO
)
3- η = 0.5 (ELUMO - EHOMO
)
4- S = -0.5 η
5- ω = ꢁ2/ 2 η
6- σ = 1/η
2.4.3. QSAR study
Surface area, hydration energy, reactivity, Polarizability and Log p are the essential QSAR
parameters calculated. HyperChem program (8.1) was used for optimizing the structural forms for ten
tested compounds. Molecular mechanics force field (MM+) followed by semi-empirical AM1 is
considered the Pre-optimization process. A free optimization process was executed without restriction
for any parameter till reaching the equilibrium state. Polake-Ribiere conjugated gradient algorithm was
the system for minimizing energy content till reach the optimized structures [28].
2.4.4. Docking process
DOCK module of MOE technique (version 2014) [29,30] caused a great revolution in drug
industry. Which is considered the pre-computational method in drug designing. Upon 2hio DNA
receptor, the hydrogen atoms were added after removing water molecules around the duplex.
MMFF94x force field, assigns the parameters and charges. Five VO(II) complexes were docked inside
minor and major grooves, after generating alpha-site spheres using MOE site-finder module. The
6

ACCEPTED MANUSCRIPT
docking scoring by MOE software in London dG scoring function and also upgraded by two unrelated
refinement methods. The geometries of docking complexes were built in the best stereo and minimal
energy, to be suitable for obtaining the best binding. The free binding energy and hydrogen bonds in
between amino acid in the receptor, were used to clarify the grad of binding between the tested
compounds and protein molecule. The hydrogen bonds were counted based on measuring the bond
length, which is not exceed than 3.5 Å.
2.5. Biodiesel synthesis
The synthesis of biodiesel from cooking waste oils, is considered the main application
interested in this study. The previous articles which interested in biodiesel synthesis, were mainly
focus on using living lime (CaO) as a catalyst [31-33]. This catalyst is known by its high activity
which needs restricted precautions during the experiment. Our process characterized by its safety and
economic. First of all, the cooking waste oil obtained (WO) was filtered off to separate solid disposal
before trans-esterification process.
2.5.1. Heterogeneous catalysis
A. Using prepared complexes
[VOSO4(CATB)] complex was chosen as a potential catalyst in biodiesel synthesis. This choice
was based on its expected reactivity, broad surface area and nano-crystalline nature as well as its
thermal stability (till 147.8°C). In a round flask, 0.25g from the complex was mixed with 30 mL waste
oil and (30 mL) methanol. The reaction mixture was stirred under reflux at 120°C for 2h. After
refluxing a mixture, the complex was filtered off by centrifuge, dried and then weighed to assert on its
catalytic role. After that, the reaction mixture was transferred to separating funnel, after 20 min, a
perfect separation was observed for two phases. The biodiesel, the less dense phase (upper layer), was
separated, washed with water then add NaCl to turn the solution clear, dried using Na2SO4 (anhydrous)
then weighed
B. Using prepared oxides
A yellow powdered oxide, was obtained from previous complex, through calcinations process.
This calcinations was carried out over a chosen complex in open air and then put in ignition oven (at;
o
650 C) for complete calcinations till a constant weight. The oxide obtained was analyzed (elemental,
XRD and SEM) to establish their chemical formulae. The reactivity, surface area and whole
7

ACCEPTED MANUSCRIPT
morphology may be significantly different from similar purchased. The heterogeneous catalytic
process (using complex) was repeated by using the prepared oxide (0.25g), for comparison. Also, such
proposed heterogeneous catalytic process, was asserted by high degree of insolubility for the complex
in the reaction medium, as well as the oxide used (V2O5). Moreover and after filtrating the catalyst, the
weight used was completely unchanged before and after the process execution.
3. RESULTS AND DISCUSSION
3.1. General features
General features estimated from analytical study (Table 1), propose 1:1 molar ration among the
ligand and vanadyl atom. The prepared complexes are stable, non hygroscopic, having high melting
points (˃300oC). All synthesized complexes are insoluble in common organic solvents except DMSO
and DMF were completely soluble. The molar conductivities (Λm) were measured for all complexes in
DMSO solvent. The values computed were found at 5.41-51.75 Ω-1cm2mol-1 rang, which covering
conducting and non-conducting features [34]. [VO(CATP)(H2O)](SO4)(H2O)2 and [VO (CATC)(H2O)2]
(SO4) complexes, were the conducting among the whole tested complexes. This may be discussed based
on the contribution of ionizable sulphate group around the coordination sphere
3.2. Mechanism of triazole preparation
4-Aminotriazole thione 3 and its schiff base 4 were synthesized previously as described in
literature reports [13]. The novel five ligands namely, 4-((4-chloro-benzylidene)-amino)-5-
trifluoromethyl-3-(aryl)-2-oxoethyl)thio-4H-[1,2,4]triazole were prepared by refluxing a mixture of
equimolar quantity of α-haloketone derivatives 5a-e and schiff base 4 in dioxane in the presence of base
catalyst Et3N. Studying all spectral data (Tables 2& 3) of the products, proved their structural forms. As
1
for example, the H-NMR spectra of all derivatives (Figs. 2 &1S) revealed in addition to the
characteristic signals for the aromatic and aliphatic protons, the presence of singlet signal due to the
methylene protons (CH2) at δ 3.74-4.80 ppm. The mechanism for the formation of ligands was
illustrated in Scheme 2. Moreover, IR spectrum of 6a exhibited the characteristic absorption bands for
stretching vibrations of NH2 group at υ = 3434 and 3152 cm-1. In addition, all derivatives revealed the
absorption bands near 1680 cm-1 in their IR spectra, which attributed to the presence of carbonyl groups
in CO-Ar moiety.
8

ACCEPTED MANUSCRIPT
H
O
O
S
OH
HO
F3C
H
N NH
+
F3C
OH
F3C
N NH
H2NHN
NHNH2
-H2O
1
S
S
2
HN
B
HN
A
NH2
NH2
O
H
HO
F3C
N
N
N NH
F3C
N NH
H
HN
H
O
F3C
S
SH
S
N
H2N
N
NH2
Cl
+
-H2O
B'
NH2
C
3
N
N
N
N
Ar
N
N
F3C
F3C
SH
S
N
N
N
F3C
SH
O
AcOH
N
N
Ar
Dioxane/Et3N
-HBr
N
+
Br
OH
H
O
6
5
D
4
Cl
Cl
Cl
Scheme. 2. The mechanism of synthesis procedure for triazole derivatives (6a-e)
3.3. The mode of bonding in complexes
The mode of binding belonging to triazole derivatives (6a-e) toward VO(II) ions, was
established based on relative shifts of function bands wavenumbers, after coordination. Table 3
summarize essential functional bands which point to bonding attitude. ν(C=O), ν(C=N) and ν(C-S)
bands suffer a noticeable lower shift which refers to covalent coordination with VO(II) atom. This
reflects the tridentate mode of bonding for triazole derivatives. νas(SO4) and νs(SO4) bands have been
observed at; 1252-1289 and 1158-1191 cm-1 ranges in [VOSO4(CATA)], [VOSO4(CATM)]2H2O and
[VOSO4(CATB)] complexes spectra. This appearance coincides to the bidentate attachment of
sulphate group towards central atom[35]. While, the spectra of [VO (CATP)(H2O)] (SO4)(H2O)2 and
[VO(CATC)(H2O)2](SO4) complexes, displayed only one band at; 1405 and 1357cm-1, respectively.
This agrees comfortably with stretching inside ionizable sulphate group. δr(H2O) and δw(H2O) bands
have appeared in most complexes spectra. The bands were at; 755- 786 and 650 - 672 cm-1 ranges,
respectively. A characteristic band attributing to ν(V=O) has clearly appeared in almost the same area
for all complexes (≈1050 cm-1); except for [VO (CATP)(H2O)](SO4)(H2O)2 (at 992 cm-1). This band
position is strongly coherent to the number of bonds surround vanadium atom [36]. The exception of
such complex may refer to differ coordination number (five) from the rest (six). New ν(V-O), ν(V-N)
and ν(V-S) bands, shined at low wavenumber region, confirm the mode of bonding for traizoles versus
VO(II) atom.
9

ACCEPTED MANUSCRIPT
3.4. Electronic transition bands
Remarkable bands were grouped and displayed in Table 4. The spectra have been obtained in
DMSO solvent by influence of Uv-Vis spectral region. π → π* and n→ π* transitions were the
significant intra ligand transitions observed at; 47619.05- 50505.0 and 32258.06-34013.61cm-1
attributing to free traizole derivatives, respectively[37]. The high degree of chromophoric conjugation
inside the molecules influences on the deep colors observed attached with charge transfer inside the
free compounds. Most of these bands suffer noticeable shift in the complexes spectra, which may
belong to coordinating groups, which orients to facilitating electronic transition pathway inside groups.
Also, in all complexes except for [VO(CATP)(H2O)](SO4)(H2O)2, significant d-d transition bands
were recorded at 11261-11494 and 14260- 15356 cm-1 ranges. According to molecular orbital theory,
2
2
these bands assign for; B2g→2Eg and B2g→2B1g in distorted octahedral geometry (Fig. 3). In the
environment of C4v symmetry, the ground state is a singlet orbital and the one electron in d is in non-
2
bonding type (dxy, B2g). The crystal field stabilization energy values (Dq) were calculated based on;
2B2g→2B1g (υ1) = 10Dq relation, and the values agree with known reported [38]. As we know that, the
value of crystal field stabilization energy, is fully matching with the first transitional band value (υ1)
through the former equation. While, the rest complex displayed 18182 and 19347 cm-1 bands, which
2
2
they attributing to B2→2E and B2→2B1 transition, respectively in square-pyramidal geometry (Fig.
4). Also, new charge transfer bands were estimated assign for O→ V, N→V and S→ V, respectively.
10

ACCEPTED MANUSCRIPT
Fig. 3. Optimized structures of VO(II) -traizole complexes
3.5. Mass spectra
Mass spectral analysis is considered the most essential tool, which used to assert the molecular
formula, particularly with failure in isolating single crystal for any synthesis. Figure 5 displays MS
spectra of two selected complexes; [VO(CATP)(H2O)](SO4)(H2O)2 and [VOSO4(CATB)]. The
spectrum of [VO(CATP)(H2O)](SO4)(H2O)2 complex shows; molecular ion peak at m/z = 606.91 (I=
2.97, calcd. 641.86) which may attribute to M+-2H2O. The dehydration process may occur during the
vaporization of complex before its bombardment by electron beam. The successive fragmentation
stages were displayed in scheme 3, which were ended by a peak at m/z = 43.06 (I = 38.85), which
agrees with vanadium isotope. The spectrum of [VOSO4(CATB)]H2O complex shows a molecular ion
peak at m/z = 666.22 (I= 2.28, calcd 666.72). The ion peak is approximately coinciding to M+. This
little difference, is logical with the presence of chlorine atom or vanadium, which are known by their
isotopic nature. Also, successive fragmentation process, was ended by a peak at m/z= 45.03(I= 10.66),
which strongly agrees with vanadium isotope [39].
11

ACCEPTED MANUSCRIPT
Scheme. 3. The proposed fragmentation for [VO(CATP)(H2O)](SO4)(H2O)2 complex
3.6. EPR study
EPR spectral analysis were conducted at; υ = 9.435 GHz, upon four investigated complexes.
The binding nature around VO(II) atom for complexes, can be obtained through computing
Hamiltonian parameters(Table 5)[40]. Vanadyl ion represents d1 systems, which transfer electron to D2
in distorted geometry. This electron occupies t2g orbitals, which corresponding to T2g (ground state
term). Eight hyperfine splitting lines, is the expected appearance of VO(II) spectra( I = 7/2). In C4v
symmetry, two sets of lines (eight lines) were predicted, while in symmetry of C2v, the expectation for
three sets of eight lines. But, the spectra of the complexes have been appeared with poor resolution and
highly smooth (Fig. 6). This may refer to high d-d interaction between neighboring centers which
affects directly on degree of lines splitting. g// ˂ g ˂ ge shows the presence of un-paired electron in dxy,
which attributing to tetragonal geometry. Isotropic and anisotropic parameters were calculated by; Ao =
(A11+2A ) ꢂ 3 and go = (g11+ 2g ) ꢂ 3 relations [41].This parameters display high degree of deviation
from free electron value (ge = 2.0023). These parameters (A and g) point to distorted tetragonal
geometry. The G values calculated from this relation; G = (g//-2.0023)/(g - 2.0023) = 4, suffer high
reduction except for square-pyramidal complex. This reduction is corresponding to high-exchange
interaction between vanadium centers in neighboring particles. Also, this high interaction orients to the
cause for smoothly curves obtained, which is considered the main reason prohibiting the resolution for
hyperfine splitting [42]. MO indexes (β2 and α2) have been calculated using known equations[43].The
values calculated reflect the highly ionic feature of in plane- σ- or π- bonding around central atom[41].
The dipole term (p) values have been calculated by known relation[44] after using the anisotropic
parameters (A// and A )by negative values. The values agree with that known for VO(II) ion. Also, the
Fermi-contact term (K) values, calculated [45], point to the relatively high magnetic interaction of
single electron with the atomic nucleus. The ability for minimizing A// value against g// value, is called
a tetrahedral distortion index (f = g///A//)[41] which clarify the high distortion of all complexes.
3.7. XRD and SEM analysis
XRD patterns have been obtained at 10˚ < 2θ < 90˚ range (Fig. 7 &2S). This analysis gave a
good view about the crystal lattice dynamics. Also, assert on purity of tested compounds from starting
materials using known methods [46].Only two patterns represent the nano-crystalline feature for
12

ACCEPTED MANUSCRIPT
corresponding complexes; [VOSO4(CATM)]2H2O (A) and [VOSO4(CATB)]. While, the rest, which
are treated in XRD study(four compounds), introduce patterns attributing to the amorphous feature.
The crystallinity advantage, may reflect a perfect building for the atomic arrays in distinct layers,
which facilitate calculating the crystal physical indexes. Using high intense peak, crystallite
parameters; 2θ, d spacing, FWHM, relative intensity, particle sizes, crystal strain (ε) and dislocation
density(δ) have been estimated (Table 6)using known equations[47].The crystallite sizes calculated fall
comfortably in nanometer range. However, the amorphous advantage for other investigated may refer
to the fast precipitation for such compounds which led to this irregularity in the arrangement of
particles or atoms. The crystal strain and dislocation density are the two indexes throwing a light on the
network dislocation. Their reduced values, point to high regularity in the crystal lattice of the two
nano-complexes. SEM images (Fig. 3S) for all tested compounds were obtained after electron beam
scanning for the solid surface. The topography, morphology and the microstructures of solid surfaces
were mostly in rocky or fused shape except for two complexes (VO-CATM and VO-CATB). The
crystallite surface of the two complexes, reflects a spherical particle shape. This agrees strongly with
XRD patterns. Also, large variation between the free derivatives and their regarding complexes
confirms the purity of VO(II) complexes from starting materials[48]. This relatively similar
topography, may refer to extreme similarity of preparation conditions conducted. The XRD, SEM and
vanadium content for oxides obtained from the calcinations for [VOSO4(CATM)]2H2O and
[VOSO4(CATB)] complexes, have been discussed. XRD pattern (Fig. 7) was matched with other
standard pattern, which likely to be V2O5 oxide. The distinctive nanometer size calculated, (Table 6)
the high strain and dislocation inside the crystal, all of them may assist its catalytic activity. Also, SEM
image display a regular morphology completely different from that of original complex. As well as the
vanadium content was determined after complete digestion for 0.02g (in conc HNO3), using a known
complexometric method [14] to verify the molecular formula suggested.
3.8. TGA analysis
Assumptions for degradation technique regarding triazole derivatives and their VO(II)
complexes have been displayed in Table 1S. The compounds have been heated (20-900oC range) at
constant heating rate (10oC min-1) under nitrogen. TGA curves for traizole derivatives displayed three
to four decomposition stages except for 6e (CATB) compound degraded in two stages. The organic
compounds displayed a complete degradation under heating system without residue, except for 6e
o
compound, leave four carbon atoms. Up to 450 C was sufficient for complete vaporization for most
organic compounds, which is logically known. TGA curves for VO(II)-traizole complexes represented
13

ACCEPTED MANUSCRIPT
three to four degradation stages upon all thermally unstable complexes except for [VOSO4(CATB)].
The mechanism of degradation was proposed separately, for each complex, depending on the structural
form of it. The lower thermal stability is the main feature observed for all complexes except for
[VOSO4(CATA)] and [VO(CATC)(H2O)2](SO4) complexes. This exception due to the absence of
crystal water molecules, which conducts to easiest degradation. Up to 800oC was sufficient for
complete distortion of coordination sphere, leaving VO2, which mainly polluted by carbon atoms still.
The plausible degradation scheme, displays an adequate conformity, about; found/ calculated mass
losses proposed in each stage.
3.9. Computational study
3.9.1. Kinetics
The kinetics upon DTG curves have been investigated for traizole derivatives and their
complexes. Only one step (1st, 2ed or 3rd) was chosen for calculating thermodynamic parameters (E,
∆H, ∆S and ∆G). The selected stage has a moderate sharpness and definite borders to facilitate
determining fraction decompose (α) versus temperature. Coats–Redfern[17] and Horowitz–Metzger
equations[22] were the two comparative methods used. The kinetics, over all degradation process, give
a great impact about the strength of whole chemical building. Also, clarify the impact of metal atoms
inserted in organic compounds upon the thermal feature of chemical structure. Over extracted plots
(Figs. 4S&5S) and applying the two methods, thermodynamic parameters have been calculated (Table
2S). ∆H = E + PV, ∆G= ∆H-T∆S and ∆S*= R ln (Ah/KbTS) were the equations used for calculation.
Whereas; kB and h are the Boltzmann and Plank’s constants, respectively. Ts is the midpoint
temperature for the selected stage. The data shown the following essential notices; i) high activation
energy values were generally recorded for complexes in comparing to relative free ligands. This may
be explained based on thermal stability for coordinating organic compounds. ii) Negative signs for ∆S
values reflect the degree of randomness for the complexes versus to original ligands. iii) The positive
∆H values introduces endothermic feature for all decomposition stages. iv) ∆G values were generally
raise in complexes which attached to the values of ∆H and ∆S.
3.9.2. DFT/B3LYP method
The best structural forms for organic derivatives (Fig. 1) and their VO(II) complexes (Fig. 3)
were extracted, applying Gaussian09 program. DFT/B3LYP was the suitable method used for
optimization process using 6-31G base set [49,a&b]. The resulted files (log and chk) were visualized
over program screen to extract essential physical parameters. EHOMO, ELUMO and ꢀE(energy gap) were
14

ACCEPTED MANUSCRIPT
the first essential indexes computing belonging to frontier levels. Such level energy values, have a
significant impact on the general characteristics for compounds. The frontiers images (HOMO &
LUMO) for all treated compounds, were displayed in Figs 8 & 6S. The HOMO levels in all traizole
ligands, appeared concentrated along traizole ring as well as aromatic-p-substituent moiety. However,
the LUMO levels appeared in the opposite site beside the traizole ring also. This represent, a high
electron density over the bound space, which is logical with the presence of intensive donor atoms in
this area of the compounds. Moreover, HOMO & LUMO images upon VO(II) complexes, displayed
divers features belonging to the distribution of such levels around the central atom. HOMO & LUMO
images reflect a high concentration around the coordinating atoms, surround vanadyl. Moreover, the
LUMO levels more prolonged over the whole molecules, in comparing to HOMO levels.
3.9.2.1. Computed physical parameters
Electronegativity (χ), chemical potential (ꢀ), global hardness (η), global softness (S), global
electrophilicity index (ω) and absolute softness (ϭ) were the estimated parameters using known
equations[26,27]. The values of these physical parameters (Table 7), were obtained based on frontiers
energy gap (ELUMO-EHOMO). Electrophilicity index (ω) is the guide for toxicity and reactivity of tested
compound. As, a measure for the ability of acquiring electrons from surrounding. With regarding to
traizole derivatives, a significant difference was recorded over all estimated physical parameters,
which may attribute to the impact of p- substituents. Regarding to complexes, essential notices were
summarized as follow; i) the complexes showed high electrophilicity values relative to their
corresponding ligands. VO(II)-CATM has the superiority in attributing to such index. ii) Global
hardness (η) and global softness (S), are two faces for the same coin, introduces the degree of
flexibility for structural form, which excellence with complexes[50,51]. iii) The ꢀE(energy gap) values
in VO(II) complexes, suffer a significant minimization, relative to original derivatives. This points to
the influence of metal atom in the molecular orbital diagrams inside the molecules. iv) Enhanced
biological feature for complexes, is strongly attached with their absolute softness (ϭ) values, which are
clearly rose beside, their reduced energy gaps [52]. According to numbering scheme, other important
characteristics were gathered from log files and showed in Table 8. Charges over coordinating atoms
(S, N and O) were extracted for the free traizole derivatives and their corresponding complexes.
Regarding to free traizole derivatives, the charges over these chosen atoms reveal a suitable variation,
which assure on the influence of p-substituents on the electron density upon a whole compound. These
charges suffer a significant reduction after complexation process. The ionic feature of new
coordinating bonds can be concluded attributing to vanadium charge which mostly affected by a strong
15

ACCEPTED MANUSCRIPT
charge transfer ( L→ V). The minimization for heat of formation in coincides to complex formation, is
an indicator for high stability of formed complexes. The increase of dipole moments, which is
coherently with the complexation, reflect the impact of metal insertion on the overall electron density.
Regarding to VO(II) complexes, unsteady oscillator strength features in comparing to free ligand, may
be attributing to variable crowding surround central atom[53].
3.9.3. QSAR parameters
Quantitative structure–property relationships (QSAR) were estimated (Table 9) upon optimized
structures from applying HyperChem(8.1) program. Surface area values clarify increasing in
complexes compared to original ligands, which considered logically after complexation. Partition
coefficient (log P) values, appeared reduced in VO(II) complexes, specifically with VO(II)-CATA and
VO(II)-CATB. This points to the high biological feature which may be expected from such two
complexes [54].While, the reactivity and polarizability values for VO(II)-CATM and VO(II)-CATB
the complexes, showed a distinguish escalating feature from original ligands. These parameters
likelihood the enhancement for whole characteristics. The reactivity, polarizability and crystallite size
were the significant characteristic for choosing the complexes suitable in catalytic application.
3.9.4. Molecular Docking study
This computational study concerning to the degree of inhibition for the docked organic
compound and protein of pathogen cells. This is considered the pre-test in drug designing. The
obtained interaction data were displayed in Table 10. Each VO(II) complex was treated using MOE
module versus 2hio DNA- protein, to conduct the inhibition view against infected cell acid[29,30]. The
results appeared discriminated binding scores, which close to lower binding mode except for VO(II)-
6d complex (Fig. 9). The ionic binding is the main type of interaction between ligand and receptor.
This may refer to ionic characteristic of most complexes as well as enriched dipole feature over
intensive functional-groups. While the other complexes were varied dramatically between moderate to
nil binding mode (Figs 7S &8S). In general the complexes herein are not likely to be the target orients
to 2hio protein receptor of infected cell-DNA, which directed us to another application pathway.
3.10. The catalytic application
The synthesis of biodiesel from waste cooking oil is major interest in this study. As we reported
previously, that the cause for this choice is the unsafe process which mostly utilized in previous
researches [55]. Formerly reported in the literature, the main catalyst used was CaO, which known by
16

ACCEPTED MANUSCRIPT
its high reactivity and several requirements, must be taken in consideration, to achieve the process with
adequate-safety. Here and regarding the safety of our proposed process, may be considered a
successful alternative-process for biodiesel synthesis. [VOSO4(CATB)] complex, was the selected one
for this application based on its distinguish capacity as; surface area, reactivity, polarizability, nano-
crystallinity, spherical particulate and thermal stability. These features may lead to significant impact
on its catalytic behavior in preparing such economic product. Moreover, the calcinations techniques
was applied upon the complex through the complete oxidation in open air and followed by ignition
o
oven(650 C). Yellow powdered oxide was obtained and fully characterized by; XRD, SEM and
vanadium content. XRD and SEM introduces patterns coincide to that attributing to V2O5 oxide in its
nano-sized spherical particles. Also, the evaluation for vanadium content asserts the formula proposed.
The sunflower waste oil (WO) has been used for biodiesel synthesis in heterogeneous catalytic process
(Figs. 10&10S). It was known that, this oil mainly consists of oleic acid as well as other fatty acids.
Trans- esterification process (Scheme 3) has been tracked upon two comparative catalysts (complex,
oxide), which they implemented at the same conditions [56,57].The oxide catalyst produced biodiesel,
by a limited yield although its normal physical properties. Density, viscosity and cloud point were the
physical parameters estimated(Table 3S) for synthesized biodiesel and have been compared with that
for ASTM-6751 Biodiesel (reference)[58-60].Finally, the process utilizing the complex displayed that,
the complex plays a best desired role in biodiesel synthesis at record time compared to oxide. This may
refer to the promising features recorded for the complex from various physical investigations among
experimental / theoretical techniques.
O
O
O
O
R1 O CH3
O
O
O
O
R1
R2
R3
OH
OH
OH
catalyst
heat
+
+
3 CH3OH
R2 O CH3
O
R3 O CH3
Scheme. 3. The transestrification of the waste oil to biodiesel
4. CONCLUSIONS
Novel VO(II)-traizole complexes, were prepared and fully characterized. Spectral and
analytical data confirmed the molecular and structural formulae for all new synthesis. The obtained
mononuclear complexes were appeared mainly in octahedral geometry. This proposal was confirmed
by UV-Vis and ESR spectral data. The conformational study was implemented to verify the structural
formulae proposed. Such, which mainly depends on the distribution of coordinating functional-groups,
that basically obtained from optimization process. While, the molecular docking study was executed
17

ACCEPTED MANUSCRIPT
by MOE module, to predict the biological activity of new complexes, before practical application. The
absence of significant biological activity, which concluded from docking process as a preliminary step
in drug designing, this orients us for another field of application, as catalysis. After that, distinguish
properties of VO(II)-CATB complex motivate to be implemented in catalytic application. This study
interested in biodiesel synthesis from cooking waste oils (WO). Moreover, the oxide of chosen
complex, which obtained after calcinations (V2O5), was also utilized from comparative point of view to
introduce the best. The complex revealed superiority in biodiesel-synthesis in comparing to its
calcinations-oxide. Distinct physical parameters estimated for synthesized biodiesel, were compatible
with standard values. The main advantage of our experiment lies in its safety and economic validity, in
comparing to others previously reported.
ACKNOWLEDGEMENTS
Prof. Nashwa El-Metwaly and co-authors would like to thank Deanship of Scientific Research at Umm
Al-Qura University (project ID: 17-SCI-1-03-0001) for the financial support to this research extracted
from the project.
REFERENCES
[1]
S.J. Yoo, H. Lee, B. Veriansyah, J. Kim, J. Kim, Y. Lee. Synthesis of biodiesel from rapeseed
oil using supercritical methanol with metal oxide catalysts. Bioresource Technology 101
(2010) 8686–8689.
[2]
[3]
[4]
C.-Y. Lin, H.-A. Lin, L.-B. Hung, Fuel structure and properties of biodiesel produced by the
peroxidation process. Fuel, 85 (2006) 1743–1749.
C. Pastore, A. Lopez, V. Lotito, G. Mascolo. Biodiesel from dewatered wastewater sludge: A
two-step process for a more advantageous production. Chemosphere, 92 (2012) 667-673.
M. Pirouzmand, M. M. Anakhatoon, Z. Ghasemi, One-step biodiesel production from waste
cooking oils over metal incorporated MCM-41; positive effect of template. Fuel, 216 (2018)
296-300.
[5]
[6]
B.R. Vahid, N. Saghatoleslami, H. Nayebzadeh, J. Toghiani, Effect of alumina loading on the
properties and activity of SO42−/ZrO2 for biodiesel production: Process optimization via
response surface methodology. J. Taiwan Institute Chem. Eng., 83 (2018) 115-123.
B. Peng, Q. Shu, J. Wang, G. Wang, D. Wang, M. Han, Biodiesel production from waste oil
feedstocks by solid acid catalysis. Process Safety and Environment Protection, 86 (2008)
18

ACCEPTED MANUSCRIPT
441-447.
[7]
[8]
A.B. Fadhil, E.T.B. Al-Tikrity, M.A. Albadree, Biodiesel production from mixed non-edible
oils, castor seed oil and waste fish oil. Fuel, 210 (2017) 721-728.
M. Weyand, H. J. Hecht, M. Kiess, M.F. Liaud, H. Vilter, D. Schomburg, X-ray Structure
Determination of a Vanadium dependent Haloperoxidase from Ascophyllum nodosum at 2.0
AÊ Resolution J. Mol. Biol. 293 (1999) 595-611.
[9]
J. N. Carter-Franklin, J. D. Parrish, R.A. Tchirret-Guth, R. D. Little, A. Butler, Vanadium
haloperoxidase-catalyzed bromination and cyclization of terpenes. J. Am. Chem. Soc. 125
(2003) 3688-3689.
[10] D. Rehder, Bioinorganic Vanadium Chemistry, John Wiley & Sons, New York, (2008).
[11] C. Bolm, Vanadium-catalyzed Asymmetric Oxidations. Coord. Chem. Rev., 237(2003) 245-
256.
[12] A. Ayati, S. Emami, A. Foroumadi, The importance of triazole scaffold in the development
of anticonvulsant agents, Eur. J. Med. Chem., 109 (2016) 380-392.
[13] M. Chen, X. Wang, S. Wang, Y. Feng, F. Chen, C. Yang. Synthesis, characterization and
fungicidal activities of novel fluorinated 3,5-disubstituted-4H-1,2,4-triazol-4-amines.
J. Fluorine Chem., 135(2012) 323-329.
[14] A. I. Vogel. Text Book Of quantitative Inorganic Analysis Longman, London (1986).
[15] G.A. Bain, J.F. Berry, Diamagnetic Corrections and Pascal's Constants. Chem. Educ., 85 (2008)
532-536.
[16] E. S. Freeman, B. Carroll, The Application of Thermoanalytical Techniques to Reaction
Kinetics: The Thermogravimetric Evaluation of the Kinetics of the Decomposition of Calcium
Oxalate Monohydrate. J. Phys.Chem., 62 (1958) 394-397.
[17] W. Coats, J. P. Redfern, Kinetic Parameters from Thermogravimetric Data. Nature, 201
(1964) 68-69.
[18] T. Ozawa, A New Method of Analyzing Thermogravimetric Data. Bull. Chem. Sot. Japan., 38
(1965) 1881-1886.
[19] W. W. Wendlandt, Thermal Methods of Analysis, New York, Wiley (1974).
[20] J. H. F. Flynn, L. A. Wall, General Treatment of the Thermogravimetry of Polymers. J. Res.
Natl. Bur. Stand. A. 70 (1966) 487-523.
[21] P. Kofstad, Oxidation of Metals: Determination of Activation Energies. Nature, 179 (1957)
1362-1363.
[22] H. W. Horowitz, G. A.Metzger, A New Analysis of Thermogravimetric Traces. Anal Chem., 35
19

ACCEPTED MANUSCRIPT
(1963) 1464-1468.
[23] X. Wu. A. K. Ray, Density-functional study of water adsorption on the PuO (110) surface.
2
Phys. Rev. B., 65 (2002) 85403-7.
[24] M. J. Frisch, et al., Gaussian 09, Revision D, Gaussian, Inc., Wallingford, CT, (2010).
[25] R. Dennington, T. Keith , J. Millam .Gauss View, Version 4.1.2, SemichemInc, Shawnee
Mission, KS, (2007).
[26] U. El-Ayaan, N. M. El-Metwally, M. M.Youssef, S. A. A. El Bialy, Perchlorate mixed–ligand
copper(II) complexes of β-diketone and ethylene diamine derivatives: Thermal, spectroscopic
and biochemical studies. Spectrochim. Acta, Part A, 68 (2007) 1278-1286.
[27] R. K. Ray, G. R. Kauffman, EPR Spectra and covalency of bis(amidinourea/O-alkyl-1-
amidinourea)copper(II) complexes Part II. Properties of the CuN42− chromophore. Inorg. Chem.
Acta, 173 (1990) 207-214.
[28] M. M. Al-Iede, J. Karpelowsky, D.A. Fitzgerald , Recurrent diaphragmatic hernia: modifiable
and non-modifiable risk factors Pediatr Pulmonol, (2015).
[29] K. H. Mashat, B. A. Babgi, M. A. Hussien, M. N. Arshad, M. H. Abdellattif, Synthesis,
structures, DNA-binding and anticancer activities of some copper(I)-phosphine complexes.
Polyhedron 158 (2019) 164–172.
[30] M. H. Abdellattif, M. A. Hussien, E. Alzahrani, New Approaches of 4-Aryl-2-Hydrazinothiazole
derivatives, molecular docking, and biological evaluations, IJPSR, 9(12)(2018)1000-1019.
[31] V. Narula, M. F. Khan, A. Negi, S. Kalra, A. Thakur, S. Jain. Low temperature optimization of
biodiesel production from algal oil using CaO and CaO/Al2O3 as catalyst by the application of
response surface methodology. Energy, 140 (2017) 879-884.
[32] J. F. Puna, J. F. Gomes, J. C. Bordado, M. Joana, N. Correia, A. Paula, S. Dias. Biodiesel
production over lithium modified lime catalysts: Activity and deactivation. Applied Catalysis
A: General, 470 (2014) 451-457.
[33] V.B. Veljković, O.S. Stamenković, Z.B. Todorović, M.L. Lazić, D.U. Skala, Kinetics of
sunflower oil methanolysis catalyzed by calcium oxide. Fuel, 88 (2009) 1554-1562.
[34] W.J. Geary, The use of conductivity measurements in organic solvents for the characterisation
of coordination compounds. J. Coord. Chem. Rev. 7 (1971) 81-122.
[35] N. M. El-Metwaly, R. M. El-shazly, I. M. Gabr, A. A. El-Asmy, Physical and spectroscopic
studies on novel vanadyl complexes of some substituted thiosemicarbazides. Spectrochim.
Acta, 61 (2005) 1113-1119.
20

ACCEPTED MANUSCRIPT
[36] K. S. Abu-Melhaa, N. M. El-Metwally, Spectral and thermal studies for some transition metal
complexes of bis(benzylthiocarbohydrazone) focusing on EPR study for Cu(II) and VO2+.
Spectrochim. Acta, Part A, 70 (2008) 277-283.
[37] A.A. Abou-Hussen, N.M. El-Metwaly, E.M. Saad, A.A. El-Asmy, Spectral, magnetic, thermal
and electrochemical studies on phthaloyl bis(thiosemicarbazide) complexes. J. Coord. Chem.
58 (2005) 1735-1749.
[38]
A. B. P. Lever Inorganic Electronic Spectroscopy, Elsevier, Amsterdam (1986).
[39] M. S. Refat, N. M. El-Metwaly, Structure and vibrational spectroscopy investigation of 2-(4-
chlorophenyliminomethyl)-8-hydroxyquinoline. Spectrochimica Acta Part A, 81 (2011) 215-
256.
[40] E. Bagdatil, E. Altuntas, U. Sayin, Synthesis and structural characterization of new
oxovanadium (IV) complexes derived from azo-5-pyrazolone with prospective medical
importance. J. Mol. Struct. 1127 (2017) 653-661.
[41] H. Yokoi, A. W. Addison, Spectroscopic and redox properties of pseudotetrahedral copper(II)
complexes. Their relation to copper proteins. Inorg. Chem. 16 (1977) 1341-1349.
[42] a) B. J. Hathaway, D.E. Billing. The electronic properties and stereochemistry of mono-
nuclear complexes of the copper(II) ion. Coord. Chem. Rev., 5 (1970) 143-207, b) B. J.
Hathaway, A new look at the stereochemistry and electronic properties of complexes of the
copper(II) ion. Struct. Bonding (Berlin), 57 (1984) 55-118.
[43] T. M. Dunn, Spin-orbit coupling in the first and second transition series. Trans. Faraday Soc., 57
(1961) 1441-1444
.
[44] B. R. Mc Garvey, The isotropic hyperfine interaction. J. Phys. Chem., 71 (1967) 51-67.
[45] M. Salagram, N. Satyanarayana , S. Radhakrishna. Semi-empirical evaluation of molecular-
orbital parameters, and spin—orbit, dipolar and fermi-contact terms of VO2+ ion in lattices.
Polyhedron, 5 (1986) 1171-1181.
[46] B. D. Cullity, Elements of X –ray diffraction. second ed., Addison –Wesley Inc., (1993).
[47] S. Velumani, X. Mathew, P.J. Sebastian, Sa.K. Narayandass, D. Mangalaraj, Structural and
optical properties of hot wall deposited CdSe thin films. Sol. Cells, 76 (2003) 347-358.
[48] J. S. Ritch, T. Chivers, K. Ahmad, M. Afzaal, P. O. Brien, Synthesis, Structures, and
Multinuclear NMR Spectra of Tin(II) and Lead(II) Complexes of Tellurium-Containing
Imidodiphosphinate Ligands: Preparation of Two Morphologies of Phase-Pure PbTe from a
Single-Source Precursor. Inorg. Chem., 49 (2010) 1198-1205; T. Mokari, M. Zhang, P. Yang,
21

ACCEPTED MANUSCRIPT
Shape, Size, and Assembly Control of PbTe Nanocrystals. J. Am. Chem. Soc. 129 (2007) 9864-
9865; J. J. Urban, D. V. Talapin, E. V. Shevchenko, C. B. Murray, Self-Assembly of PbTe
Quantum Dots into Nanocrystal Superlattices and Glassy Films. J. Am. Chem. Soc., 128 (2006)
3248-3255.
[49]
1-
A) I. Althagafi, M. G Elghalban, F. Saad, J. H Al-Fahemi, N. M El-Metwaly, S.
Bondock, L. Almazroai, K. A Saleh, G. A Al-Hazmi, Spectral characterization, CT-DNA
binding, DFT/B3LYP, molecular docking and antitumor studies for new nano-sized VO (II)-
hydrazonoyl complexes, J. of Mol. Liq., 242(2017)662; B) G. A Al-Hazmi, K. S Abou-
Melha, N. M El-Metwaly, K. A Saleh , Synthesis of Novel VO (II)-Perimidine Complexes:
Spectral, Computational, and Antitumor Studies, , Bioinorganic Chemistry and
ApplicationsVolume 2018( 2018) Article number 7176040
[50] R. C. Chikate, S. B. padhye, Transition metal quinone–thiosemicarbazone complexes 2:
Magnetism, ESR and redox behavior of iron (II), iron (III), cobalt (II) and copper (II)
complexes of 2-thiosemicarbazido-1,4-naphthoquinone. Polyhedron, 24 (2005) 1689-1700.
[51] H. Allal, Y. Belhocine, E. Zouaoui. Computational study of some thiophene derivatives as
aluminium corrosion inhibitors. J. Mol. Liq., 265 (2018) 668-678.
[52] I. Fleming, Frontier Orbital's and Organic Chemical Reactions, Wiley, London, (1976).
[53] S. K. Tripathi, R. Muttineni, S. K. Singh, Extra precision docking, free energy calculation and
molecular dynamics simulation studies of CDK2 inhibitors. J. Theor. Biol., 334 (2013) 87-100.
[54] F. A. Saad, J. H. Al-Fahemi, H. El-Ghamry, A. M. Khedr, M. G. Elghalban, N. M. El-Metwaly,
Elaborated spectral, modeling, QSAR, docking, thermal, antimicrobial and anticancer activity
studies for new nanosized metal ion complexes derived from sulfamerazine azodye. J. Therm.
Anal. Calorim., 13 (2018), 1249-1267.
[55] Z. Kesic, I. Lukic, M. Zdujic, L. Mojovic and D. Skala, Calcium Oxide Based Catalysts for
Biodiesel production( Review), Chem. Ind. Chem. Eng. Q . 22 (4) 391−408 (2016)
[56] N. Terakado, S. Shintani, Y. Nakahara, Expression of Cu,Zn-SOD, Mn-SOD and GST-pi in
oral cancer treated with preoperative radiation therapy. Oncol Rep, 7 (2000) 1113-1120.
[57] V. Singh, M. Yadav, Y. C. Sharma. Effect of co-solvent on biodiesel production using
calcium aluminium oxide as a reusable catalyst and waste vegetable oil. Fuel, 203 (2017)
360-369.
[58] I. B. Banković–Ilić, M. R. Miladinović, O. S. Stamenković, V. B. Veljković, Application of
nano CaO–based catalysts in biodiesel synthesis. Renewable and Sustainable Energy
22

ACCEPTED MANUSCRIPT
Reviews, 72 (2017) 746-760.
[59] N.A. Negma, G.H. Sayed, O.I. Habiba, F.Z. Yehia , E.A. Mohamed, Heterogeneous catalytic
transformation of vegetable oils into biodiesel in one-step reaction using super acidic
sulfonated modified mica catalyst. J. Molecular Liq., 237 (2017) 38-45.
[60] L.M. Correia, N.S. Campelo, D.S. Novaes, C.L. Cavalcante Jr, J.A. Cecilia, E. Rodríguez-
Castellón, R.S. Vieira, Characterization and application of dolomite as catalytic precursor for
canola and sunflower oils for biodiesel production. Chem. Eng. J., 269 (2015) 35-43.
23

ACCEPTED MANUSCRIPT
Table 1 Analytical data of triazole derivatives (6a-e) and their VO(II) complexes
Λm, Ohm-
Compounds
Color
Elemental analysis (%) Calcd (Found)
Cl
1cm2 mol-1
(Empirical formula )
C
H
N
S
V
---
1) (C18H13ClF3N5OS)(CATA,6a)(439.84)
2)[VO SO4(CATA)](602.84)
Yellow
49.15(49.14) 2.98(2.96) 15.92(15.92) 8.06(8.05)
7.29(7.29) ------
6.30
---
Olive green 35.86(35.85) 2.17(2.15) 11.62(11.60) 5.88(5.89)
Brown
52.00(52.05) 3.21(3.20) 12.77(12.78) 8.08(8.08)
Olive green 35.78(35.79) 2.84(2.82) 8.78(8.77)
5.56(5.53)
50.89(51.02) 2.85(2.84) 13.19(13.21) 8.35(8.36)
33.68(33.65) 2.83(2.87) 8.73(8.76) 5.52(5.55)
10.64(10.62) 8.45(8.41)
7.31(7.30) ------
3) (C19H14ClF3N4OS)(CATM,6b)(438.85)
4)[VO SO4(CATM)]2H2O(637.88)
5.41
---
10.05(10.10) 7.99(8.02)
7.55(7.57) ------
5) (C18H12ClF3N4OS)(CATP,6c)(424.82)
6)[VO (CATP)(H2O)](SO4)(H2O)2(641.86)
7) (C18H11Cl2 F3N4OS)(CATC,6d)(459.27)
8)[VO (CATC)(H2O)2](SO4)(658.30)
9)(C18H11BrClF3N4OS)(CATB,6e)(503.72)
10)[VO SO4(CATB)](666.72)
Brown
Brown
51.75
---
9.99(10.10) 7.94(7.95)
Faint yellow 47.07(47.02) 2.41(2.40) 12.20(12.18) 15.44(15.41) 6.98(695)
------
44.63
---
Olive green 32.84(32.85) 2.30(2.28) 8.51(8.47)
Yellow
42.92(42.92) 2.20(2.19) 11.12(11.12)
10.77(10.76) 9.74(9.70) 7.74(7.73)
6.37(6.36) ------
Cannot determined
5.81
Olive green 32.43(32.56) 1.66(1.69) 8.40(8.39)
9.60(9.57) 7.64(7.63)
Cannot determined
Table 2 1H, 13CNMR data for triazole derivatives (6a-e)
Compounds
1H NMR
13C NMR
6a, CATA
2.14 (s,2H, NH2), 4.80 (s,2H, CH2), 6.75- 41.68 (CH2), [114.28, 121.84, 129.11, 129.55, 130.17,
8.20 (m, 8H, Ar-H), 8.21 (s, 1H, N=CH).
130.93, 133.60, 134.02, 139.30, 142.53, 148.50,
160.39(Ar-C)], 196.50 (C=O)
6b, CATM
6c, CATP
6d, CATC
6e, CATB
1.60 (s,3H, CH3), 3.74 (s, 2H, CH2), 7.30- 38.28 (CH3), 55.52 (CH2), [128.13, 129.17, 129.49,
8.02 (m, 8H, Ar-H), 8.64 (s, 1H, N=CH).
129.76, 129.90, 130.14, 132.11, 132.43, 135.27,
135.60, 142.11, 142.80 (Ar-C)], 194.37 (C=O)
4.12 (s,2H, CH2), 7.16 (s,1H,N=CH) 45.05 (CH2), [116.45, 119.14, 123.93, 125.90, 128.27,
7.19-7.85 (m, 9H, Ar-H).
128.36, 131.54, 135.94, 136.65, 140.54, 147.15,
155.07(Ar-C)], 190.86 (C=O)
4.25 (s,2H, CH2), 6.80-7.91(m, 9H, Ar-H) 48.0 (CH2), [116.48, 119.17, 127.55, 127.70, 128.20,
and N=CH).
128.93, 129.39, 129.72, 130.04, 143.82, 144.09,
154.97 (Ar-C)], 195.0 (C=O)
4.03 (s,2H, CH2), 7.29 (s,1H, N=CH), 49.20 (CH2), [119.08, 127.94, 128.16, 128.93, 129.46,
6.73-7.95 (m, 8H, Ar-H).
130.16, 131.40, 132.68, 132.89, 143.40, 150.03,
154.07 (Ar-C)], 193.21 (C=O)
1

ACCEPTED MANUSCRIPT
Table 3 Functional IR spectral bands (cm-1) of triazole derivatives (6a-e) and their VO(II) complexes
δr(H2O),δw(H2O)
Compounds
νOH,νCH-Ar νC=O νC=N νC-S νas(SO4) νs(SO4)
νV=O νM-O νM-N νM-S
NH2,3434,3152
3428,3153
......,3154
1679 1603 679
1673 1591 653 1289 1158 ----
1687 1585 677 ---- ---- ----
1677 1576 666 1270 1160 755, 650
----
----
----
---- ---- ---- ----
1054 619 519 478
---- ---- ---- ----
1049 610 554 470
---- ---- ---- ----
992 593 B. c. 513
---- ---- ---- ----
1048 604 524 474
---- ---- ---- ----
1058 606 542 470
1) 6a, CATA
2)[VO SO4(CATA)]
3) 6b, CATM
B.C. 3428
.....,3187
4)[VO SO4(CATM)]2H2O
5) 6c, CATP
1658 1572 687
1615 1560 672
1677 1567 680
1670 1533 657
1682 1569 655
----
ν, ionic,1405
---- ----
ν, ionic, 1357
---- ----
----
----
B.c. 3440
772, 672
----
6)[VO (CATP)(H2O)](SO4)(H2O)2
7) 6d, CATC
......,3151
3473,3152
786, 660
----
8)[VO (CATC)(H2O)2] (SO4)
9)6e, CATB
......, 3064
-----
1671 1528 640 1252 1191
----
10)[VO SO4(CATB)]
B. c. Broad centered
Table 4 Electronic transition bands (cm-1) for triazole derivatives (6a-e) and their VO(II) complexes
Compounds
ꢀ(eff) Dq d-d transition Intraligand and charge
Complex
Geometry
(cm-1) bands (cm-1) transfer(cm-1)
(B.M.)
-----
1.73
-----
1.74
-----
1.78
------
1426 11261; 14260
------
47619.05; 32258.06
------
1) 6a, CATA
50505.05; 34013.6; 25510.2
49504.95; 33783.78
Octahedral
------
2)[VO SO4(CATA)]
3) 6b, CATM
1535.6
11494; 15356
------
51546.39;34246.57; 32051.28; 24154.59 Octahedral
4)[VO SO4(CATM)]2H2O
5) 6c, CATP
50505.05; 34013.60; 24038.46
49103.25; 33015.23; 25343.25
------
Square-pyramidal
18182; 19347
6)[VO (CATP)(H2O)](SO4)(H2O)2
------
------
50505.05;34013.61
------
7) 6d, CATC
1.78
----
1532.1 11494; 15321
------
50000.0; 34246.57; 24271.84
49504.95; 34013.61
Octahedral
------
8)[VO (CATC)(H2O)2](SO4)
9)6e, CATB
1.75
1487.3 11364; 14873
49456.74; 26178.01
Octahedral
10)[VO SO4(CATB)]
Table 5 Spin – Hamiltonian parameters computed for most VO(II) complex (A and p x10-4)
β2
g
A
α2
G
p
k
Complex
g//
go
A11
f
Ao
2) [VO SO4(CATA)]
1.927 1.971 1.956 161 119.69 62 95.00
1.929 1.971 1.957 160 120.56 65 96.67
2.406 115.09 0.779 1.102 1.530
2.342 110.45 0.830 1.124 1.531
4
6
8
)[VO SO4(CATM)]2H2O
)[VO(CATP)(H2O)](SO4)(H2O)2 1.920 1.979 1.959 175 109.71 73 107.00 3.532 ----
----
1.964 1.090
) [VO (CATC)(H2O)2](SO4)
1.933 1.973 1.960 162 119.32 68 99.33
2.365 109.29 0.867 1.052 1.533
2

ACCEPTED MANUSCRIPT
Table 6. XRD parameters for nano-crystalline complexes
δ(Å-2)
Intensity
Size (Å) 2θ
d-spacing
(Å)
FWHM
Compounds
ε
3.339
3.103
1.462
25.07 753.4
18.86 420.0
26.25 240.3
3.5492
4.7015
6.7845
0.1276 0.08969 0.4443
0.1817 0.10386 0.4731
1)[VO SO4(CATM)]2H2O
2)[VOSO4(CATB)]
3) V2O5
2.8016 0.4678
0.4286
Table 8. Estimated physical parameters upon optimized structures by DFT/B3LYP method
(EH - EL)
Compounds
EH (eV) EL (eV) (eV)
El-Eh
x(eV)
µ(eV)
η(eV)
S(eV-1)
ω(eV)
ϭ(eV)
CATA
-0.21524 -0.09152
-0.1237 0.12372 0.15338 -0.15338 0.06186 0.03093 0.190151 16.16553508
-0.0863 0.0863 0.20229 -0.20229 0.04315 0.021575 0.474174 23.17497103
-0.1581 0.15812 0.17009 -0.17009 0.07906 0.03953 0.182966 12.6486213
-0.078 0.07798 0.22462 -0.22462 0.03899 0.019495 0.647014 25.64760195
-0.1618 0.16184 0.16941 -0.16941 0.08092 0.04046 0.177334 12.35788433
-0.0725 0.07252 0.16476 -0.16476 0.03626 0.01813 0.374322 27.57859901
-0.1549 0.15487 0.182815 -0.18282 0.077435 0.038718 0.215802 12.91405695
-0.0565 0.05648 0.16789 -0.16789 0.02824 0.01412 0.499063 35.41076487
-0.1566 0.15658 0.17445 -0.17445 0.07829 0.039145 0.194359 12.77302337
-0.1049 0.10492 0.21518 -0.21518 0.05246 0.02623 0.441312 19.06214258
VO(II)+CATA -0.24544 -0.15914
CATM
-0.24915 -0.09103
VO(II)+CATM -0.26361 -0.18563
CATP
-0.25033 -0.08849
VO(II)+CATP -0.20102 -0.1285
CATC
-0.26025 -0.10538
VO(II)+CATC -0.19613 -0.13965
CATB
-0.25274 -0.09616
VO(II)+CATB -0.26764 -0.16272
Table 9 Considerable bond lengths, charges, Heat of formation (E), dipole moment(D), oscillator strength(ʄ)and excitation
energies(E)
Compounds
S6 / S7
(coordinated)
0.442405
N15/ N16 O9/ O10
V
E
(A.U.)
D
(Debye)
ʄ
E
(nm)
(coordinated)
coordinated)
-2200.10305276 4.3324 0.0003 403.84
-3920.26108263 18.1672 0.0004 11834.2
CATA
-0.150616
-0.409986 -------
/ 0.026146 / 0.001056
0.443330 -0.142443
/0.200855 -0.197636
VO(II)+CATA
CATM
VO(II)+CATM
CATP
VO(II)+CATP
CATC
VO(II)+CATC
CATB
-2184.06749538 3.1809 0.0185 342.17
-3904.22467118 8.3523 0.0036 8988.13
-2144.75414290 3.1744 0.0316 335.04
-3241.34103856 7.0427 0.0002 2125.97
-2604.73939397 3.5916 0.0074 351.01
-3700.44294622 6.6361 0.0015 5768.26
-4715.73185415 3.4109
-0.395659 -------
/ 0.090623 / 0.004075 / 0.330341 -0.280582
0.445146 -0.132537 -0.394706 -------
/ 0.126080 / -0.002343 / -0.078191 1.700495
0.397484 -0.110515 -0.327687 -------
/ 0.043118 / 0.008932 /-0.003311 0.314163
0.449863 -0.150324 -0.390935 -------
/ 0.100144 / 0.039138 / 0.250164 -0.056450
0.0128
346.48
VO(II)+CATB
-6437.00965246 7.2977 0.0162 4807.21
3

ACCEPTED MANUSCRIPT
Table 10 Computational QSAR parameters for optimized triazole derivatives and their VO(II) complexes
VO-CATA VO-CATM VO- CATP VO-CATC VO-CATB
Function
6a
6b
6c
6d
6e
Surface area (Approx) (Å2) 574.23 611.51 568.37 602.71
614.09 583.08
679.00 672.13
610.77
683.11
562.93
642.41
600.48
667.81
603.09
697.01
1238.13
-18.10
1.86
Surface area (Grid) (Å2)
655.29 663.22 638.97 658.00
Volume (Å3)
1077.75 1097.92 1045.71 1088.84 1108.19 1198.82 1217.51 1113.25 1158.03
Hydration energy(Kcal/mol) -16.07 -9.72
-10.90 -10.45
4.45 4.23
114.32 115.06 110.77 115.49
40.58 41.06 39.22 41.15
-10.57 -26.40
4.50 1.23
118.31 129.09
41.85 42.08
-20.02
3.10
-24.85
2.57
-24.61
2.35
Log P
2.73
4.60
Reactivity (Å3)
Polarizability (Å3)
129.82
43.56
117.28
39.72
121.99
41.65
133.20
43.49
Table 11 Interaction parameters for VO(II) complexes against calf thymus DNA (2hio) complexes
Complex
Ligand Receptor
Interaction Distance(Å) E ( Kcal/mol) S( energy score)
6-ring N ARG 134 (C) pi-H
4.67
-0.8
-1.2
-3.7
-6.3282
-5.5948
VO(II)-6a
VO(II)-6b
F
27
30
NZ LYS 99 (A) H-acceptor 3.04
C
Ionic
3.13
NZ LYS 99 (A
)
-6.1536
-6.3398
VO(II)-6c ----
----
----
----
3.07
3.39
3.78
3.39
----
4.0
-2.3
-1.0
-2.3
O
8
OD2 ASP 68 (B) Ionic
VO(II)-6d
S
11
OE2 GLU 71 (B) Ionic
N
N
28 OE1 GLU 71 (B) Ionic
28 OE2 GLU 71 (B)
-6.2867
VO(II)-6e ----
----
----
----
----
4

ACCEPTED MANUSCRIPT
Fig. 2. NMR spectra of 4-((4-Chloro-benzylidene)-amino)-5-trifluoromethyl-3-((4-methyl-phenyl)-2-oxoethyl)thio-
4H-[1,2,4]triazole (6b, CATM) derivative
Fig. 4. UV-Vis spectra for two selected complexes
1