Quantum, characterization and spectroscopic studies on Cu(II), Pd(II) and Pt(II) complexes of 1-(benzo[d]thiazol-2-yl)-3-phenylthiourea and its biological application as antimicrobial and antioxidant

Article abstract of DOI:10.1016/j.molstruc.2017.04.065

Divalent platinum, palladium and copper chelates of H₂PhT have been isolated and identified. Their structures have been elucidated by partial elemental analyses, magnetic susceptibilities and spectroscopic estimations and additionally mass spec

Full text of DOI:10.1016/j.molstruc.2017.04.065

Accepted Manuscript
Quantum, characterization and spectroscopic studies on Cu(II), Pd(II) and Pt(II)
complexes of 1-(benzo[d]thiazol-2-yl)-3-phenylthiourea and its biological
application as antimicrobial and antioxidan
Suhair M. S. Jamb
PII:
S0022-2860(17)30507-0
10.1016/j.molstruc.2017.04.065
MOLSTR 23688
DOI:
Reference:
To appear in:
Journal of Molecular Structure
Received Date:
Revised Date:
Accepted Date:
24 January 2017
15 April 2017
17 April 2017
Please cite this article as: Suhair M. S. Jamb, Quantum, characterization and spectroscopic studies
on Cu(II), Pd(II) and Pt(II) complexes of 1-(benzo[d]thiazol-2-yl)-3-phenylthiourea and its biological
application as antimicrobial and antioxidan, Journal of Molecular Structure (2017), doi: 10.1016/j.
molstruc.2017.04.065
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ACCEPTED MANUSCRIPT
Molecular electrostatic potential map for H PhT.
2

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2
+
2+
2+



Preparation of Cu , Pd and Pt complexes of phenylthiourea
derivatives.
Elemental analysis, magnetic susceptibilities and spectroscopic
estimations of the ligand and its complexes.
Molecular modeling, chemical reactivity, MEP, NLO, Mulliken atomic
charges, and binding energy were estimated for the investigated
compounds.
1


Theoretical infrared intensities and H NMR of the ligand was
computed utilizing DFT technique.
DNA bioassay, antibacterial and antifungal activities of the compounds
have been determined.

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Quantum, characterization and spectroscopic studies on Cu(II), Pd(II) and
Pt(II) complexes of 1-(benzo[d]thiazol-2-yl)-3-phenylthiourea and its
biological application as antimicrobial and antioxidant
Abstract
Divalent platinum, palladium and copper chelates of H PhT have been isolated and
2
identified. Their structures have been elucidated by partial elemental analyses, magnetic
1
susceptibilities and spectroscopic estimations and additionally mass spectra. The FTIR and H
NMR studies illustrated that H PhT performs as mono-negative bi-dentate in Cu(II) and Pd(II)
2
complexes while it behaves as neutral bi-dentate in both Pt(II) complexes. Both magnetic moments
and spectral studies suggests a tetrahedral coordination geometry for [Cu(HPhT)(H O)Cl]
2
complex, a square planar geometry for both [Pd(HPhT) ] and [Pt(H PhT) Cl ] complexes and
2
2
2
2
octahedral geometry for [Pt(H PhT) Cl ] complex. The molecular modeling are drawn and
2
2
2
demonstrated both bond lengths and angles, chemical reactivity, MEP, NLO, Mulliken atomic
charges, and binding energy (kcal/mol) for the investigated compounds. Theoretical infrared
1
intensities and H NMR of H PhT was computed utilizing DFT technique. An examination of the
2
experimental and hypothetical spectra can be extremely valuable in making right assignments and
analyzing the main chemical shift. DNA bioassay, antibacterial and antifungal activities of the
investigated compounds have been determined.
Key words: Thiazole, thiourea, DFT, NLO, theoretical IR, DNA bioassay and antimicrobial
studies.
1
. Introduction
Thioureas containing thiazole ring and their chelates have found wide applications in
exceptional pharmacological items as penicillin and vitamins. They can bind DNA, RNA, in
addition to their anti-diabetic, anti-cancer, anti-viral, anti-microbial and anti-fungal properties.
Also, literature survey of thioureas transition metal chelates, particularly platinum chelates
illustrated interesting applications in anticancer medications. As a ligand, the thiazole moiety is
conceivably ambidentate and can coordinate the metal ions either through the thione or thiol forms.
2
+
2+
2+
The ability of thiazoles to coordinate to Cu , Pd and Pt , soft acids, indicated coordination to
the marginal base azomethine nitrogen atom and thiazole sulfur atom [1-4]. With regards to the

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above applications, we have reported here the synthesis and spectroscopic studies on the ligand
(
H PhT) and its Cu(II) , Pt(II) and Pd(II) chelates. The proposed structures were supported by
2
geometry optimization of the ligand and its chelates.
2
. Experimental
2
.1.
Materials and Instruments
The following compounds were bought from Sigma Aldrich and utilized as received. The
elemental analyses were done on Research Center, College of Pharmacy, and KSU Riyadh using
a Perkin–Elmer elemental instrument”. Standard techniques was utilized to estimate the contents
of metal and chloride in the chelates [5]. Estimation of the molar conductance for the chelates in
“
1
13
DMF was estimated utilizing “a Tacussel bridge (CD6NG)”. H- and C NMR were obtained with
a JEOL 400 MHz NMR spectrometer, in deuterated dimethylsulfoxide (DMSO-d ) at room
6
temperature utilizing tetramethylsilane (TMS) as an internal standard. D O-exchange was utilized
2
to affirm the identification of the NH- signals. Fourier transform infrared (FTIR) spectra were
recorded using a Bruker Tensor 27 FTIR spectrophotometer (Bruker Optics GmbH, Ettlingen,
Germany) utilizing KBr pellets. Unicam UV–Vis spectrophotometer were utilized to record UV–
Vis. spectra. The estimation of magnetic moment was done on a “Sherwood magnetic balance” at
푚푎푠푠
푚
( ).
o
2
5 C. EI-MS were measured on Finnigan 711A (8 kV) and recorded as
푐ℎ푎푟푔푒 푧
2
.2.
Preparation of 1-(benzo[d]thiazol-2-yl)-3-phenylthiourea (H PhT)
2
By mixing 1:1 molar ratio of 2-aminobenzothiazole (1.50 g, 0.01mol) and phenyl
isothiocyanate (1.35 g, 0.01mol) in 30 ml hot ethanolic solution. The reaction mixture was refluxed
for 3.5 hrs. Pale yellow precipitate was separated after cooling, then isolated, recrystallized by hot
C H OH and lastly desiccated over P O . The purity was checked by TLC. C H N S (285.38).
2
5
2
5
14 11
3 2
%
Found (Calcd.): C 58.62 (58.92), H 3.65 (3.89), N 14.64 (14.72). Mass spectrum: m/z = 285 (63%)
corresponding to (C H N S ).
1
4
11
3 2
2
.3.
Synthesis of metal complexes
Cu(HPhT)(H O)Cl], [Pd(HPhT) ] and [Pt(H PhT)Cl ] chelates were synthesized by
[
2
2
2
2
refluxing H PhT (0.285 g, 1.0 mmol) and 1.0 mmol of metal salt; 0.17 g of CuCl .2H O, 0.22 g of
2
2
2
Pd(CH COO) or 0.42 g of K PtCl in 20 ml ethanol for 6 h. On the other hand, [Pt(H PhT) Cl ]
3
2
2
4
2
2
2
was prepared by using 2.0 mmol of H PhT ligand with 1 mmol of K PtCl . The produced hot
2
2
4
chelates were separated, washed with C H OH then C H OC H and desiccated over P O .
2
5
2
5
2
5
2
5

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2
.4.
Quantum chemical computations
The main errand for the theoretical studies is to decide the most stable geometry of H PhT
2
and its metal chelates. Computational DFT were performed for H PhT by (B3LYP) function
2
together utilizing “6-311++G(d,p)” basis set while semi-empirical method was utilized for the
complexes to infer the entire geometry stabilization and ordinary-style examination for separated
chelates [6-8]. Lorentzian band shapes with full width at half maximum was utilized to sketch the
calculated IR spectrum. The improved structure was utilized to register the minimal spin-permitted
electronic vertical excitation energies utilizing (B3LYP) with standard Pople basis set that
incorporates diffuse functions on atoms (6-311 ++ G (d, p). The electronic properties, for example
frontier molecular orbitals, dipole moments and infrared intensities were ascertained.
Computations on proton magnetic shielding values were done utilizing (GIAO) approach
[9, 10] for gas phase. This methodology permits the calculation of the indisputably chemical
shielding because of the electronic surroundings of the respective cores. The chemical shift was
estimated hypothetically by using the exact level of speculation on TMS. DFT studies have been
utilized to ascertain the dipole moment, mean polarizability and first static hyperpolarizability into
account the constrained field ideology. The basic and spectroscopic portrayal of a unfaltering
molecule was done utilizing Gaussian 09 program bundle on the private PC [11].
2
.5.
DNA-methyl green bioassay [12, 13]
00 ml of 0.05 M Tris-HCl buffer (pH 7.5) containing 7.5 mM MgSO was added to 20
1
4
mg of DNA methyl green; the mixture was disintegrated at 310 K for 24 h. Test samples 10,100,
000 mg) were dissolved in ethanol in Ependoff tubes. After that, the solvent was evacuated under
1
vacuum, then a solution containing 200µl of the DNA/methyl green was poured into each separate
Ependoff. Samples were hatched at surrounding temperature. Beyond one day, the absorbance of
the samples was evaluated at 645 nm. Readings were adjusted for starting absorbance and
standardized as the rate of the unstained standard.
2
.6.
Antimicrobial and antimycotic activities in terms of MIC (µg/mL) [14]
The anti-bacterial behavior of H PhT and its divalent Cu, Pd and Pt chelates was
2
investigated against strains disengaged from animal by-products and were blamed for being
immediate reason of nourishment inebriation in human. The strains incorporate Staphylococcus
aureus “Gram-positive bacteria” and Escherichia coli “Gram-negative bacteria” utilization Muller

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Hinton agar medium. The anti-fungal behavior of the materials were studied against (Candida
albicans) using Sabouraud dextrose agar medium (Oxoid). Ciprofloxacin (100 µg/ml) and
Fluconazole (100 µg/ml) were utilized as standard for hostile to bacterial and against parasitic
movement.
Agar steak dilution method was utilized to determine MIC of the investigated compounds.
1
00 µg/ml stock solution of the studied compound in DMSO and measured amounts of the studied
materials were consolidated in a determined amount of molten sterile agar (Muller Hinton agar for
anti-microbial studies and “Sabouraud dextrose agar” one for anti-parasitic action). A pre-
determined amount of this medium at 50 °C containing the material was poured into a Petri dish
to yield a profundity of 4 mm and permitted to densify. 105 cfs/ml of a suspension of the micro-
organism was applied to plates with serially diluted compounds in DMSO to be checked and
incubated at 37 °C for one and two days for microbes and parasites, individually. The MIC is the
least amount of the investigated material showing no unmistakable development of
microorganisms or organisms on the plate.
3
. Results and discussion
Table 1 outlines the data of elemental analysis and some physical properties of the chelates.
The stoichiometries of the coordination adducts set up by elemental analysis are affirmed by
geometry optimization. The non-electrolytic nature of the chelates was assessed by the small
2
-1
-1
quantity of molar conductivity (1.0 – 17.0 cm ohm mol ) [15]. Disappointingly, single crystals
of the investigated chelates cannot be obtained. The purity of the H PhT ligand was examined by
2
TLC (silica gel). The chelates were non-hygroscopic and insoluble in typical organic solvents but
soluble in DMSO. All the chelates showed melting point above 300 ⁰C.
3
.1.
IR spectra
The IR spectrum of H PhT and its divalent chelates were performed as KBr disc in the
2
-1
4
000-400 cm scope. Table 2 demonstrates the FTIR spectra of H PhT and its chelates. The IR
2
−
1
1
2
spectrum of H PhT displays bands at 3436, 3162 and 804 cm , attributable to υ(N –H), υ(N -H)
2
−
1
and υ(C=S), individually. There are no bands in the 2290-2495 cm range attributable to υ(S-H)
which confirms the existence of H PhT in the thione form in the solid state (Structure 1a). The
2
-1
bands at 1569 and 1528 cm due to ν(C=C) and ν(C=N) of the thiazole ring vibrations,
consequently. In both Cu and Pd complexes (Structures 2, 3), H PhT acts as a mono-negative bi-
2

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dentate ligand attached to the nitrogen atom of the thiazole moiety and the C=S group in the thiol
1
isomer. This behavior is illustrated by (i) the absence of υ(N –H), (ii) the movement of ν(C=N)
Py
frequeny. (iii) the shift of ν(C=S) peaks to lower wavenumbers with the appearance of new bands
at 1535, 1527, 1156 and 1132 due to ν(N=C-S) and ν(C-S), respectively. In both platinum chelates
(
Structures 4, 5), H PhT behaves as a neutral bi-dentate attached to the nitrogen atom of the
2
thiazole moiety and the C=S group of the thione form. This behavior is confirmed by (i) the shift
1
of υ(N –H) to large wavenumber. (ii) the shift of ν(CS) to lower wavenumber, proposing the
2
coordination to Pt(II) by the thione-Sulfur atom while the υ(N –H) band moved to higher
wavenumbers.
Structure 1a. Molecular modeling of H PhT in
Structure 1b. Molecular modeling of H PhT in
2
2
the thione form.
the thiol form.

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Structure 2. Molecular modeling of [Cu(HPhT)(H O)Cl].
2
Structure 3. Molecular modeling of [Pd(HPhT)2].

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Structure 4. Molecular modeling of [Pt(H PhT)Cl ].
2
2
Structure 5. Molecular modeling of [Pt(H PhT) Cl ].
2
2
2
3
.2.
1H NMR spectra
1
The H NMR spectrum of the H PhT in DMSO-d illustrates the existence of the ligand in
2
6
the thiol form in solution (Structure 1) under the test settings. The presence of signals at 1.92 and
0.46 ppm assignable to (SH) and (NH)protons, respectively. The signals of all aromatic hydrogen
1
are in the range of (7.28 – 7.95 ppm) equivalent to 10 protons of the thiol tautomer. In case of both
1
platinum chelates, the signal at 10.46 ppm assignable to (NH) protons in the H NMR spectrum of
1
the ligand still exist in the H NMR spectrum of these complexes but shifted to downfield
confirming the neutrality of the ligand and the coordination via both C=S and C=N groups while
the signal at 1.92 ppm due to (SH) proton disappears. Further evidence for deprotonation of the
1
thiol group in [Pd(HPhT) ] comes from the H NMR spectrum, asserting the weakness of the
2
signals of the (NH) protons while the signal at 1.92 ppm due to SH proton disappears.
3
.3.
13C-NMR spectra
1
3
The C-NMR spectra of H PhT and its divalent chelates in DMSO-d illustrated signals
2
6
assignable to carbon atoms in the phenyl, thiazole and C=S groups. The following points can be

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illustrated by comparing the chemical shift values of the chelates with those of H PhT: (i) An
2
upfield move for the (CS) carbon from 172.00 ppm in the H PhT to 170.84 ppm in [Pd(HPhT) ]
2
2
II
containing the mono-anion ligand. This is due to the complexation of the S atom to Pd metal.
(
ii) An upfield move for the (C=S) carbon from 172.00 ppm in H PhT to 171.06-169.08 ppm in
2
II
both Pt chelates containing the neutral ligand. (iii) No obvious pattern was noticed in the shift of
signals of aromatic ring carbons. The previous behavior might be credited to the contradicting
impact of σ-electron withdrawing and π-bonding donation over those carbons that are affected by
the coordinated metals [16, 17].
3
.4.
Electronic spectra and magnetic behavior
All chelates are diamagnetic at 300 K, with the exception of Cu(II) one which has
paramagnetic property (μ = 1.93 B.M./Cu atom). This indicate a tetrahedral arrangement around
eff
divalent palladium and platinum chelates. The electronic spectra of the ligand and its chelates were
displayed in Nujol mull. The spectrum of the H PhT ligand shows an intense absorption band at
2
2
61 nm assignable to π → π* transition of thiazole ring. Another intense band is seen at 298 nm
-1
(
33557 cm ) attributable to π → π* of (C=N) group which shifts in chelates to higher frequencies,
proving the complexation of H PhT via (C=N) nitrogen atom. The band at 361 nm
2
azomethine
attributable to (n→π*)thiazole, transitions. Electronic spectra of copper complex can be an indicator
of its geometry [18]. The electronic spectrum of Cu complex shows an absorption band in the
region of 370 nm indicating a four-coordinated geometry of Cu(II) [18, 19]. The band at 273 nm
might be attributable to intra-ligand charge transfer (CT) transitions.
The coordination and the kind of the metal affects this band as illustrated by marginally
shorter wavelengths moves with splitting in both divalent Pt and Pd chelates. This might be
credited to the broad delocalization of π system by the clear π-back coordination M→L between
2
+
2+
Pt and Pd ions and both CS and CN atoms. The new band showed up at 316 and 341 nm in
Pt(II) chelates.
The d-d bands from the spectra of the Pd chelate having low intensities appeared at 461
1
1
nm and were assigned to the A → A transition in square planar environment around palladium
1
g
2g
[16, 20]. Other bands from the spectra of the complex are too intense to be assigned to d-d
transition.
3
3
.5.
Molecular modeling
.5.1. IR

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Frequency estimation were done to earn the spectroscopic mark of H PhT. There are little
2
contrasts amongst hypothetical and exploratory vibrational wavenumbers as appeared in Fig. 1.
The main reason for this difference is that the calculation were done for uncoordinated H PhT in
2
vacuum, yet the examinations were accomplished for solid H PhT. The vibrational modes of
2
H PhT are exceptionally complex because of its low symmetry. Particularly, torsion, in- and out-
2
of plane modes are hard to allocate as a result of interpreting with the ring modes furthermore with
the derivative. In any case, there are some clear frequencies helpful to describe in the obtained
chart. The correlation graphic portrayed concordance between the hypothetical and experimental
wavenumbers (Fig. 2). There is linear relationship between the hypothetical and experimental
wavenumbers as depicted by the next equation:
2
vcal =0.98683vexp + 18.5772 with correlation coefficients (R = 0.99985).
1
3
.5.2. H NMR
The structure of bulky compounds can be investigated by combined utilization of
experimental and computational tools. The obtained structure of H PhT after optimization is
2
1
utilized to figure the H NMR spectrum at B3LYP strategy with 6-311++G(d,p) level utilizing the
GIAO method and the chemical shifts of H PhT are accounted for in ppm in respect to TMS for
2
1
1
H NMR which are introduced in Table 3. Theoretical H NMR has a signal at 10.71 ppm
attributable to only one NH proton confirming the presence of H PhT in the thiol form in a solution.
2
3
3
.5.3. Chemical reactivity
.5.3.1. Global reactivity descriptors
The assurance of energies of the HOMO and LUMO are essential criterion in quantum
estimations. The HOMO “Highest Occupied Molecular Orbitals” is the one which principally
behaves as an electron donor. On the other hand, the LUMO “Lowest Unoccupied Molecular
Orbital” is the orbital that greatly behaves as the electron receiver. These orbitals are additionally
named frontier molecular orbitals (FMOs).
i. The EHOMO and ELUMO and the adjoining levels are practically negative. This illustrate the
stability of the isolated chelates [21-24].
ii. The FMOs hypothesis anticipate sites of electrophilic attack on aromatic ligands. The
combination among these orbitals is an administering element in numerous responses. One has
the ability to demonstrate that by the computation via scanning for the biggest estimations of

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atomic orbital coefficients. Thus, orbitals of H PhT with the biggest quantity of coefficients
2
might be treated as the places suitable for complexation. The previous outcome is affirmed by
the information acquired from the computation since nitrogen of (C=N)azomethine and sulphur of
(C=S)thione showed the biggest quantities.
iii. Gutmann’s variation principle, ‘‘the bond strength increases as the neighboring bonds get to
be weaker’’ which proved by Linert et al. [25]. This explanation agrees well with the results
as the increase of the EHOMO is accompanied by a weakness “elongation” of the M–L bonds.
This promotes a fortifying “shortness” of the distances beside the M-L sites.
iv. The energy gap (∆퐸 = EHOMO - ELUMO) is an a critical indicator that describes the chemical
reactivity and kinetic stability for the investigated material [21]. H PhT is characterized by
2
small energy showing that charge move fluently happens in it. The aforementioned factor
affect the biological behavior of H PhT. The conjugation is the main reason for the small
2
energy [26]. DFT strategy idea the substance reactivity and site selectivity of the atomic
frameworks. EHOMO, ELUMO, ∆퐸 which clarifies the inevitable charge exchange collaboration
inside the studied material, electronegativity (χ), potential (µ), hardness (η), softness (S),
electrophilicity (ω) and the softness (ϭ) [27, 28] are recorded in Table 4.
χ = -1/2 (ELUMO + EHOMO
)
(1)
(2)
(3)
(4)
(5)
µ= - χ =1/2 (ELUMO + EHOMO
)
η =1/2 (ELUMO - EHOMO
S =1/2 η
)
2
ω = µ /2 η
Electrophilicity record is a standout amongst the most critical quantum descriptors in
depicting toxicity of various toxicity of different contaminations as far as their reactivity and site
selectivity [29]. Likewise, the electrophilicity appropriately evaluates the biological behavior of
medication receptor collaboration. This new reactivity record estimates the stabilization in energy
when the framework obtains more electronic charge from the surrounding. The significance of η
and ϭ is used to estimate both reactivity and stability.
3
.5.4. Geometry optimization using DFT study
For the discussion of the optimized molecular structure. Examination of the information
figured for the bond distances and angles, the following points can dedicated:

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1
2
. The HOMO level is largely localized on the N(7) and S(13) atoms (Fig. 3) showing
that these atoms are the favored destinations for nucleophilic reaction at the central
cation.
. The counts demonstrated that the charge dispersion of the HOMO level of Cu-chelate
II
is exceptionally confined on the lone pair of N and S atoms, and d-orbital of Cu - atom,
(Fig. 4). The charge density of the LUMO level is, for the most part, distributed on the
the nitrogen atoms and the phenyl group (Fig. 4).
3
4
. While in Pd(II) chelate (Fig. 5), the charge distribution of the HOMO level is
delocalized on the d-orbital of palladium and the lone pair of sulfur atom. On the other
hand, the charge density of the HOMO level of Pd(II) and Pt(II) complexes is conveyed
over the entire system.
. Likewise, the charge of the LUMO level is exceedingly delocalized over the entire
moiety of the chelate and on d-orbital of Pd and Pt metals (Figs. 5- 7). It was concluded
from the above explanation that there is σ-donation from H PhT to the d-orbital of the
2
metal together with back donation from the d-orbital of the metal atom to H PhT which
2
enhances the stability of the examined chelates.
3
.5.5. Molecular electrostatic potential (MEP)
The MEP is defined as a figure of electrostatic potential charted onto the stationary electron
density surface. MEP is likewise extremely accommodating in research of the structure with its
physio-chemical relationship and also hydrogen bonding collaborations [30-32]. This potential
“
V(r)” at any distance “r (x, y, z)” is characterized as far as the cooperation energy between the
charge created by the proton, electrons and nuclei situated at this distance [33]. Calculation of this
potential is feasible for particles utilizing the Γ-point and different k-focuses. In the recent paper,
3
D graphs of “MEP” of H PhT and its metal chelates (Figs. 8-12) have been drawn. In can be
2
concluded that the greatest negative area favored for electrophilic reaction is shown by the red
color, while the most extreme positive district favored for nucleophilic reaction is illustrated by
the blue color. The increase in the potential can be ordered as follow: blue > green > red, where
blue demonstrates the powerful attraction while the red illustrates the powerful repulsion. Areas
with negative values are distributed on nitrogen and sulfur atoms while the regions having the
positive values are distributed on the hydrogen atoms.
3
.5.6. Polarizability and Hyperpolarizability

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DFT hypothesis has been utilized as an effective strategy to examine the organic nonlinear
optical materials. The associations of electromagnetic fields in different media to create another
fields changed in phase, frequency, amplitude or other propagation characteristics from the
incident field gives rise to NLO [34]. The polarizability and hyperpolarizability describe the
reaction of a framework in any given electric field [35]. They could decide not just the quality of
the strength of molecular communications (for example, the long-range induction, and dispersion
forces), the cross-areas of various scattering and collision forms, additionally, the NLO of the
framework [36]. The hypothesis of electric polarizability is a main component of the normal
translation of an extensive variety of phenomena, from nonlinear optics and electron scattering
[37] to ones initiated by intermolecular collaborations..
1
1
E = E° ‒ µ 퐹 ‒ 2훼 퐹 퐹 ‒ 6훽 퐹 퐹 퐹 + …
훼 훼
훼훽 훼 훽
훼훽훾 훼 훽 훾
Where E° is the energy of unperturbed molecule, F the field at the starting point, µ , α and β
αβγ
α
α
αβ
are the components of dipole moment, polarizability and the first order hyperpolarizabilities,
respectively. The total dipole moment (µ), the mean diole polarizability (α), the anisotropy of the
polarizability (Δα) and the total first order hyperpolarizability βtotal, utilizing x, y, z components
they are defined as
2
푥
2
푦
2 1/2
푧
µ = (µ + µ + µ )
훼 + 훼 + 훼
푧푧
푥푥
푦푦
‹
α› =
3
‒
1/2
2
2
2
2 1/2
푥푥
훥훼 = 2
[
(훼 ‒ 훼 ) + (훼 ‒ 훼 ) + (훼 ‒ 훼 ) + 6훼
]
푥푥
푦푦
푦푦
푧푧
푧푧
푥푥
2
푥
2
푦
2 1/2
푧
훽푡표푡푎푙 = (훽 + 훽 + 훽 )
And
훽푥 = 훽
푥푥푥
푦푦푦
+ 훽푥푦푦 + 훽푥푧푧
+ 훽푥푥푦 + 훽푦푧푧
훽푦 = 훽
훽푧 = 훽 + 훽푥푥푧 + 훽푦푦푧
푧푧푧
In the recent study, the estimated dipole moment, polarizability and first order hyperpolarizability
values are calculated and listed in Table 5.

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3
.5.7. Mulliken atomic charges
Mulliken atomic charge computation has a noteworthy part in the use of quantum
concoction estimation to molecular framework on account of atomic charges impact, electronic
structure, molecular polarizability, dipole moment and other properties of the framework. The
estimated values of H PhT are recorded in Table 6. Figure 8 illustrates the charge distribution
2
structure of H PhT. The S(8) and N(7) atoms revealed a negative charge because of their donating
2
property. Moreover, S(8) atom has bigger ones more than N(7) atoms. Hydrogen atoms display
positive charges because of its accepting property. Figure 13 illustrates the atoms numbering of
H PhT.
2
3
.6.
DNA-methyl green bioassay
All prepared compounds were evaluated in the DNA methylgreen assay (Fig. 14). H PhT
2
ligand and [Pd(HPhT) ] complex exhibited the most potent activity as a DNA interacting agent,
2
with an IC value of 34.5 and 39.8 µg/ml, respectively, while [Pt(H PhT)Cl ] and [Pt(H PhT) Cl ]
5
0
2
2
2
2
2
complexes showed moderate DNA interacting properties with IC value of 47.1 and 61.3 µg/ml,
5
0
respectively. [Cu(HPhT)(H O)Cl] complex exhibited the lowest DNA interacting activity.
2
3
.7.
Antimicrobial and Antimycotic Activities in terms of MIC (µg/mL).
All the isolated compounds were assayed in vitro against E. coli ATCC 25922, S.
aureus ATCC 25923 for the determination of antibacterial activity. C. albicans ATCC 10231 was
utilized for the assurance of antifungal behavior. Ciprofloxacin and fluconazole were utilized as
reference medications in order to compare the antimicrobial activity. As found in Table 7, the
H PhT and its chelates demonstrated diverse action against standard Gram-negative microbes “E.
2
coli, P”, H PhT has the highest antibacterial activity with MIC value of 4.68 followed by
2
[
Pd(HPhT) ] complex. H PhT and its [Pd(HPhT) ] complex demonstrated interesting behavior
2 2 2
against the tested Gram-negative strains “S. aureus”. H PhT showed higher antibacterial activity
2
against S. aureus with MIC value equals 3.12 μg/ml related to the control medication. Table 7
demonstrated that all compounds introduced diverse MICs against C. albicans contrasted with the
control fluconazole (1.17 μg/ml). Both H PhT and [Pd(HPhT) ] showed the highest antifungal
2
2
activity against C. Albicans as compared with fluconazole. [Cu(HPhT)(H O)Cl] complex showed
2
the lowest antibacterial and antiviral activities among the prepared compounds.
4
. Conclusion

ACCEPTED MANUSCRIPT
Divalent platinum, palladium and copper chelates of H PhT have been isolated by the
2
reaction of 2-aminobenzothiazole and phenyl isothiocyanate. The ligand H PhT behaves as
2
monobasic bi-dentate in Cu(II) and Pd(II) chelates while it behaves as neutral bi-dentate in both
Pt(II) complexes. The spectral analysis reveals a tetrahedral coordination geometry for
[
Cu(HPhT)(H O)Cl], a square planar geometry for both [Pd(HPhT) ] and [Pt(H PhT) Cl ] and
2 2 2 2 2
octahedral geometry for [Pt(H PhT) Cl ]. The solid IR confirmed the presence of the ligand in the
2
2
2
1
13
thione form while H- and C-NMR spectra suggested the presence of H PhT in the thiol form in
2
solution. The molecular modeling are drawn and indicated chemical reactivity, MEP, NLO,
Mulliken atomic charges, and total energy for all the isolated compounds. Theoretical infrared
1
intensities and H NMR of H PhT was calculated using DFT method. An examination of the
2
exploratory and hypothetical spectra can be extremely helpful in making right assignments and
comprehension the fundamental synthetic chemical shift. The DNA bioassay, antibacterial and
antifungal activities of the prepared compounds have been screened. The H PhT and [Pd(HPhT) ]
2
2
exhibited the most potent activity as a DNA interacting agent. In addition, H PhT has the highest
2
antibacterial activity followed by [Pd(HPhT)2].
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[
2

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Fig. 1. Comparison of experimental and theoretical IR spectra of H PhT.
2
Fig. 2. The linear regression between the experimental and theoretical (keto form) frequencies of
H PhT.
2

ACCEPTED MANUSCRIPT
ELUMO= -2.79eV
excited state)
(
EHOMO= -5.15 eV
ground state)
(
Fig. 3. 3D plots frontier orbital energies using DFT method for H PhT.
2

ACCEPTED MANUSCRIPT
ELUMO= -8.32eV
excited state)
(
EHOMO= -15.56 eV
ground state)
(
Fig. 4. 3D plots frontier orbital energies using DFT method for [Cu(HPhT)(H O)Cl].
2

ACCEPTED MANUSCRIPT
ELUMO= -1.63 eV
excited state)
(
EHOMO= -8.30 eV
ground state)
(
Fig. 5. 3D plots frontier orbital energies using DFT method for [Pd(HPhT)2].

ACCEPTED MANUSCRIPT
ELUMO= -2.21 eV
excited state)
(
EHOMO= -8.40 eV
ground state)
(
Fig. 6. 3D plots frontier orbital energies using DFT method for [Pt(H PhT)Cl ].
2
2

ACCEPTED MANUSCRIPT
ELUMO= -0.056eV
excited state)
(
EHOMO= -8.63 eV
ground state)
(
Fig. 7. 3D plots frontier orbital energies using DFT method for [Pt(H PhT) Cl ].
2
2
2

ACCEPTED MANUSCRIPT
Fig. 8. Molecular electrostatic potential map for H PhT.
2
Fig. 9. Molecular electrostatic potential map for [Cu(HPhT)(H O)Cl].
2

ACCEPTED MANUSCRIPT
Fig. 10. Molecular electrostatic potential map for [Pd(HPhT)2].
Fig. 11. Molecular electrostatic potential map for [Pt(H PhT)Cl ].
2
2

ACCEPTED MANUSCRIPT
Fig. 12. Molecular electrostatic potential map for [Pt(H PhT) Cl ].
2
2
2
Fig. 13. The Mulliken charge distribution for H PhT.
2

ACCEPTED MANUSCRIPT
Fig. 14. DNA/methyl green colourimetric assay of the DNA-binding compounds (IC values
5
0
represent the concentration (mean ± SD, n = 3-5 separate determinations) required for a 50%
decrease in the initial absorbance of the DNA/methyl green solution).