Synthesis, molecular modeling, TD-DFT, antimicrobial, and in vitro therapeutic activity of new spherical nano-sized sulfonamide imine ligands and their zinc (II) and copper (II) complexes

Article abstract of DOI:10.1002/aoc.5953

A series of nanometer-sized spherical sulfonamide imine ligands HL¹-HL⁵ and their copper and zinc complexes were synthesized and fully characterized based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM) studies, m

Full text of DOI:10.1002/aoc.5953

Received: 16 April 2020
DOI: 10.1002/aoc.5953
Revised: 12 July 2020
Accepted: 14 July 2020
F U L L P A P E R
Synthesis, molecular modeling, TD-DFT, antimicrobial, and
in vitro therapeutic activity of new spherical nano-sized
sulfonamide imine ligands and their zinc (II) and copper
(II) complexes
Ali El-Dissouky1 | Eslam S. Abu-Elsoud1 | Afaf Abdel Razik1
|
Mohamed K. Awad2 | Hammed H.A.M. Hassan1 | Amel F. Elhusseiny1
1Chemistry Department, Faculty of
A series of nanometer-sized spherical sulfonamide imine ligands HL1-HL5
Science, Alexandria University, 2 Bagdad
street, PO Box 2-Moharrem Beck,
and their copper and zinc complexes were synthesized and fully characterized
Alexandria, 21321, Egypt
2Theoretical Applied Chemistry Unit
based on elemental analyses, spectroscopic (UV/vis, FT-IR, NMR, EPR, SEM)
studies, molar conductance and thermal analyses. Furthermore, computational
(TACU), Chemistry Department, Faculty
of Science, Tanta University, Tanta, Egypt
studies of HL1-HL5 were carried out by the DFT/B3LYP method. TD-DFT,
HOMO and LUMO energy values, chemical hardness, electronegativity, elec-
trophilic index, softness, and other parameters were calculated. Screening
against several pathogenic microorganisms indicated that HL1 exhibited high
activity against the tested Gram-negative bacteria relative to other analogues
and the inhibition activity is greater than the standard Gentamicin. Analo-
gously, HL2 exhibited high potent activity against the tested Gram-positive
bacteria. Copper complexes exhibited a higher potent activity than zinc ana-
logues. Noteworthy, inhibition activity of [Cu (L3)(OAc)] complex is higher
than that of the standard Ampicillin. [Cu (L2)(OAc)] complex displayed a simi-
lar activity of the standard bactericides and fungicides in use. The complexes
showed appreciated values of MIC against bacterial strains: B. subtilis
(MIC = 0.4 μg / mL), E. coli and S. pneumonia (MIC = 1.95 μg / mL) and
P. aeruginosa (MIC = 7.81 μg / mL). in vitro cytotoxic activities study proved
that [Cu (L3)(OAc)] complex exhibited appreciable activity versus (HEPG-2);
IC50 = 4.8 μg/ml, while [Cu(L2)(OAc)] complex showed a high activity against
(MCF-7); IC50 = 6.2 μg/ml. These results could be considered as new findings
of promising antitumor candidates for experimental chemotherapy.
Correspondence
Amel F. Elhusseiny, Chemistry
Department, Faculty of Science, Alexandria
University, 2 Bagdad street, PO Box
2-Moharrem Beck, 21321 -Alexandria,
Egypt.
Email: amel_elhusseiny@sci.alexu.edu.eg
K E Y W O R D S
complexes, computational studies, cytotoxicity, nanomaterial, spectroscopic
1 | INTRODUCTION
of human infections and many animal systems.[1] Their
chemical structures, enriched with nitrogen, sulfur
Sulfa-drugs are ligands possess potent biological activity
because of their crucial role in eliminating a wide range
and oxygen groups, offered a great tendency to form
metal complexes. Chemical modification by reaction with
Appl Organomet Chem. 2020;e5953.
wileyonlinelibrary.com/journal/aoc
© 2020 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.5953

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EL-DISSOUKY ET AL.
varieties of aldehydes, ketones or chelation with metals
furnished biologically active and powerful corrosion
inhibitors.[1–4]
The copper and zinc ions were described as ions of
interest for several biological processes.[5] These ions
are key factors in cellular metabolism and activate
many critical enzymes functions in protein and DNA
syntheses.[6] Their coordination modulated protein
structures for clarifying biological function and occurred
as a core factor in protein revenue and misfolding of
protein- illnesses.[7] Furthermore, these ions possess
antioxidant and pro-antioxidant properties against
accelerated ageing and injury healing.[8] As an antioxi-
dant, copper scavenges free radicals and diminish their
damage effect.[9] As a pro-oxidant, on the contrary, it sup-
ports free radical damage and adds to the advance of
Alzheimer's sickness.[10] Zinc ions are active antimicro-
bial agents even at low concentrations. It may be a neuro-
toxin, proposing zinc homeostasis showing a serious role
in normal brain operations and central nervous
system.[11] Cu proteins have different characters in bio-
logical electron transport and oxygen transportation trig-
gering easy Cu(I) ! Cu (II) interexchange. Copper is
essential for phospholipids production found in periph-
eral nerves.[12]
FIGURE 1 Structures of the sulfonamide imines HL1-HL5
to understand the structure of the ligands, upon using
geometry optimization and HOMO-LUMO analysis.
(iii) the synthesis and the characterization of their copper
and zinc complexes. (iv) the evaluation of in-vitro bacteri-
cidal and fungicidal activities of all the prepared com-
pounds and the Minimum Inhibitory Concentration
(MIC) activities against a panel of microorganisms.
(v) the study of in vitro cytotoxicity and the IC50 versus
the selected mammalian cell lines, breast cancer (MCF7),
liver cancer (HEPG2), and colon cancer (HCT116).
The use of inherently nanostructured bioactive
materials for nanotherapy is an encouraging method
for future active chemotherapy. Many organic materials
could be prepared in a quite precise way to form
various nanoscale structures down to the molecular
scale. Such nanomaterials could be synthesized either by
2 | EXPERIMENTAL
interfacial techniques or by emulsion method.
A
commonly used method for organic nanoscale materials
preparation is solvent displacement referred to nano-
precipitation.[13] This method includes the dissolution of
the monomers in an organic, water-miscible solvent,
which is then added to the aqueous phase in the presence
or absence of a surfactant. In addition to the aqueous
phase, the organic solvent instantly spreads out leading
to the development of nanoscale materials.
In the current study, we present (i) the preparation
and characterization of new nanosized sulfonamide-
imine ligands, Figure 1, namely; 4-{[(1E)-(2-hydroxy-
1-salicyl)methylene]-amino}-N-(4,6-dimethyl pyrimidin-
2-yl)benzenesulfonamide (HL1), 4-{[(1E)-(2-hydroxy-
1-salicyl)methylene]-amino}-N-(4-methyl pyrimidin-2-yl)
benzene sulfonamide (HL2), 4-{[(1E)-(2-hydroxy-
1-naphthyl)methylene]amino}-N-(4,6-dimethylpyrimidin-
2-yl) benzenesulfonamide (HL3), 4-{[(1E)-(2-hydroxy-
1-naphthyl) methylene]amino}-N-(4-methyl pyrimidin-
2-yl)benzenesulfon amide (HL4) and 4-{[(1E)-(2-hydroxy-
2.1 | Materials and solvents
4-amino-N-(4,6-dimethylpyrimidin-2-yl) benzenesulfona-
mide
(sulfamethazine),
4-amino-N-(4-methyl
pyrimidin-2-yl) benzenesulfonamide (sulfamerazine),
4-amino-N-(pyrimidin-2-yl) benzene sulfonamide (sulfa-
diazine), salicylaldehyde and 2-hydroxynaphthaldehyde
were purchased from Aldrich. Ethanol (BDH-
PROLABO), dimethyl sulfoxide (DMSO, Aldrich) and
diethyl ether were of pure grade quality and used as
received. Hydrated divalent copper and zinc acetates
were purchased from Aldrich and used as received.
2.2 | Physical measurements
Microanalyses of carbon, hydrogen, nitrogen, and sulfur
were carried out at the Regional Centre of Mycology and
Biotechnology, El-Azhar University, Cairo. The metal
analysis was performed by the atomic absorption
technique, Faculty of Science, Alexandria University, in
1-naphthyl)methylene]amino}
-N-pyrimidin-2-yl)
benzenesulfonamide (HL5). (ii) the TD-DFT calculations

EL-DISSOUKY ET AL.
3 of 23
SCHEME 1 Synthesis of
sulfonamide imine ligands HL1- HL5
and their Cu (II) and Zn (II) complexes.>
addition to complexometric titration using standard
EDTA solution in the presence of a suitable metal
indicator at the appropriate pH. The melting points of
the prepared compounds were measured using an
electro-thermal melting point apparatus and were not
corrected. FT-IR spectra (KBr pellets; 3 mm thickness)
were carried out on a Perkin-Elmer FT-IR Spectropho-
tometer (FT-IR 1650). All spectra were recorded within
the wavenumber range of 4,000–500 cm−1 at room
Giza-Egypt. Thermal analyses were recorded in the tem-
ꢀ
ꢀ
perature range from 25 C to 1,000 C using LINSEIS
STA PT1000 thermogravimetric analyzer. The experimen-
tal conditions were as follows: the platinum crucible and
the heating rate were 10 ꢀC/min. and the maximum sam-
ple weight was 10 mg, at the central laboratory unit, Fac-
ulty of Science, Alexandria University. The morphologies
of nanosized organic ligands were detected by Scanning
Electron Microscope (SEM) (JEOL-JSM5300), at the E-
Microscope Unit; Faculty of Science, Alexandria Univer-
sity. Sonication of samples was done in de-ionized water
for 5 min, then deposited onto a carbon-coated copper
mesh and allowed to air-dry before the examination.
Antimicrobial Screening tests and Cytotoxicity studies
were accomplished at the Regional Centre of Mycology
and Biotechnology, El-Azhar University, Cairo.
temperature 25
1
ꢀC. Electronic spectra were per-
formed using a UV 500 UV–vis spectrophotometer at
room temperature (RT) as dimethyl sulphoxide solutions.
The 1H-NMR spectra were carried out on a JEOL
500 spectrometer as DMSO-d6 solution with TMS as an
internal standard at Faculty of Science Alexandria Uni-
versity. Molar conductivity measurements were measured
ꢀ
using HI 8033 HANNA conductometer at 25 1 C for
10−3 M DMSO solution. Digital Orion pH/ISE meter was
used for the pH measurements. EPR measurements on
polycrystalline copper samples were measured at room
temperature 298 K using a high sensitivity standard
cylindrical resonator (ER 4119HS) operating at 9.8 GHz,
with a 100 kHz modulation frequency and DPPH as an
external standard at National Institute for standards–
2.3 | Synthesis of organic ligands HL1-
HL5 (general method)
The organic ligands HL1-HL5 were synthesized
according to the reported procedure with a slight
modification.[14,15] The aldehydes namely; salicylaldehyde

4 of 23
EL-DISSOUKY ET AL.
(0.4 mL, 3.50 mmol) or 2-hydroxy-1-naphthaldehyde
(0.6 g, 3.7 mmol) dissolved in absolute ethanol(25 mL)
was added to a warm solution of the appropriate sul-
fonamides (3.50 mmol) namely: Sulfamethazine(1.0 g),
sulfamerazine(0.94 g) or sulfadiazine (0.87 g) in absolute
ethanol (15 mL). The mixture was acidified with drops
of glacial acetic acid followed by reflux for four hours.
After the mixture was cooled, the orange solid product
was isolated and recrystallized from ethanol. The rec-
rystallized precipitate was isolated by filtration, washed
with ethanol, ether and dried under vacuum at 60 ꢀC
for 24 h and then kept in a vacuum desiccator. The
compounds were checked for purity by TLC and their
sharp melting points
2.3.3 | 4-{[(1E)-(2-Hydroxy-1-naphthyl)
methylene]amino}-N-
(4,6-dimethylpyrimidin-2-yl)
benzenesulfonamide (HL3)
ꢀ
Yield 80.5%; m.p. 237 C; yellow solid. Anal. Calc. for
C23H20N4SO3 (%): C, 63.8; H, 4.60; N, 12.9; S, 7.4. Found
(%): C, 63.7; H, 4.3; N, 12.7; S, 7.1; FT-IR(ν, cm−1): 3444,
1,589, 1,350, 1,245, 1,153. UV–Vis (λmax, nm): 260, 320,
1
420. H-NMR (δ, ppm): Singlet OH signal at δ11.72, two
singlets at δ 9.65 and δ 9.64, aromatic protons at δ 8.74,
δ 8.72, δ 8.29–8.26 ppm (m), δ 8.09–8.02 (m), δ
7.87–7.82 (m), δ 7.70–7.65 (m), δ 7.63–7.62 (mδ7.61–7.60
(m), δ 7.59–7.58 (mδ7.56–7.50 (m), δ7.42–7.37 (m), δ
7.18–7.15 (m), δ6.88–6.85 (m), δ 6.68–6.66 (m), δ
6.58–6.55 (m), δ 2.23 (s, 3H, majorδ 2.20 (s, 3H, CH3,
minor).
2.3.1 | 4-{[(1E)-(2-Hydroxy-1-salicyl)
methylene]-amino}-N-(4,6-dimethyl
pyrimidin-2-yl) benzenesulfonamide (HL1)
2.3.4 | 4-{[(1E)-(2-Hydroxy-1-naphthyl)
methylene]amino}-N-(4-methyl pyrimidin-
2-yl) benzene sulfonamide (HL4)
ꢀ
Yield 95.4%; m.p. 265 C; yellow solid. Anal. Calc. for
C19H18N4SO3 (%): C, 59.6; H, 4.70; N, 14.6; S, 8.3.
Found (%): C, 59.5; H, 4.4; N, 14.6; S, 8.5; FT-IR
(ν, cm−1): 3393, 1,595, 1,238, 1,310, 1,149. UV–Vis
(λmax, nm): 260, 355, 400. 1H-NMR (δ, ppm): Four
ꢀ
Yield 96.4%; m.p. 247 C; yellow solid. Anal. Calc. for
C22H18N4SO3 (%): C, 63.1; H, 4.3; N, 13.3; S, 7.6. Found
(%): C, 63.3; H, 4.5; N, 13.6; S, 7.7; FT-IR(ν, cm−1): 3436,
1,570, 1,338, 1,245, 1,151. UV–Vis (λmax, nm): 260, 320,
420. 1H-NMR (δ, ppm): Broad deuteratable OH at δ
11.73, δ 9.57 (s, 1H, H1), δ 8.43 (d, j 9.0 Hz, 1H, arom), δ
8.31 (d, j 6.0 Hz, 1H, arom), δ 8.07 (2d, j 8.7 Hz, 6 Hz, 1H,
arom), δ7.93 (d, j 9.0 Hz, 1H, arom), δ 7.74 (2d, j 6.2 Hz,
6.4 Hz, 2H, arom), δ 7.55 (2d, j 7.8, 7.8 Hz, 1H, arom), δ
7.36 (2d, j 7.2 Hz, 7.8 Hz, 2H, arom), δ 7.00 (d, j 9.3 Hz,
1H, arom), δ 6.91 (2d, j 5.1 Hz, 1H, arom), δ 2.32 (s, 3H,
CH3).
CH3 protons signals at
2.28 ppm, 2.26 ppm., CH=N proton at δ 8.93 ppm,
8.90 ppm, 8.89 ppm. Deuteratable broad
δ 2.23 ppm, 2.20 ppm,
δ
δ
singlet signal at δ 5.21 ppm NH proton. The aromatic
protons δ 6.57–6.49 (m, 1H), δ 6.64–6.62 (m, 1H),
δ 6.72–6.65 (m, 1H), δ 6.84–6.80 (m, 1H), δ 7.03–6.87
(m, 1H), δ 7.43–7.38 (m, 1H), δ 7.50–7.46 (m, 1H),
δ
7.77–7.55 (m, 1H),
δ 8.03–8.01 (m, 1H) and
δ 8.17–8.08 (m, 1H).
2.3.5 | 4-{[(1E)-(2-hydroxy-1-naphthyl)
methylene]amino}-N-pyrimidin-2-yl)
benzene sulfonamide (HL5)
2.3.2 | 4-{[(1E)-(2-Hydroxy-1-salicyl)
methylene]-amino}-N-(4-methylpyrimidin-
2-yl) benzene sulfonamide (HL2)
ꢀ
Yield 96.3%; m.p. 291 C; yellow solid. Anal. Calc. for
Yield 96%; m.p. 180 ꢀC; yellow solid. Anal. Calc. for
C18H16N4SO3 (%): C, 58.6; H, 4.30; N, 15.2; S, 8.6.
Found (%): C, 58.6; H, 4.2; N, 15.4; S, 8.8; FT-IR(ν,
cm−1): 3436, 1,594, 1,340, 1,245, 1,160.. UV–Vis (λmax,
nm): 260,355, 400. 1H-NMR (δ, ppm): Broad singlet
OH signal at δ11.77 ppm, two singlet signals at δ10.14
and δ10.13 corresponding to 1H and aromatic protons
resonated at δ 8.86 ppm (2 s δ 8.24–8.22 ppm (m) δ
8.0 ppm (m), δ7.66–7.60 (m) δ7.54–7.48 (m), δ7.47–7.42
(m), δ6.99–6.94 (m) δ6.86–6.83 (m), δ6.58–6.55 (m),
δ2.27 (s, 3H, major), δ 2.29 (s, 3H, minor).
C21H16N4SO3 (%): C, 62.3; H, 3.9; N, 13.8; S, 7.9. Found
(%): C, 62.1; H, 4.1; N, 14.2; S, 8.1; FT-IR(ν, cm−1): 3436,
1,570, 1,338, 1,245, 1,151. UV–Vis (λmax, nm): 260, 320,
1
420. H-NMR (δ, ppm): Singlet broad deuteratable OH at
δ11.83, δ9.59 (s, 1H), aromatic protons resonated at δ.51
(d, j 6.6 Hz, 1H), δ.45 (d, j 8.7 Hz, 1H), δ.03 (d, j 8.7 Hz,
1H), δ7.93 (d, j 9.3 Hz, 1H), δ7.76 (2d, j 7.2 Hz, 8.4 Hz,
2H), δ 7.60 (d, j 6.0 Hz, 1H), δ7.52 (2d, j 7.2 Hz, 7.2 Hz,
2H), δ7.35 (2d, j 7.2 Hz, 7.8 Hz, 2H), δ 7.06 (2d, j 4.8 Hz,
4.8 Hz, 2H), δ 6.96 (2d, j 9.0 Hz, 1H), δ 6.56 (2d, j 9.0 Hz,
1H).

EL-DISSOUKY ET AL.
5 of 23
2.4 | Synthesis of nanosized organic
ligand HL1–HL5 (general method)
2.5.3 | [cu (L2)(OAc)]
Yield 94%; m.p. >300 ꢀC; green solid. Anal. Calc. for
C20H18N4SO5Cu (%): C, 49.0; H, 3.6; N, 11.4; S, 6.5; Cu,
12.9. Found (%): C, 49. 2; H, 3.4; N, 11.6; S, 6.7; Cu, 12.9.
Λm (Ω−1mol−1cm2) = 2; FT-IR (ν, cm−1): 3444, 1,607,
1,567, 1,410, 1,339, 1,278, 1,161, 505, 446. UV–Vis (λmax,
nm): 260, 320, 415, 700.ESR: g1 = 2.05, g2 = 2.14,
g3 = 2.26; Rr = 0.57; <g> = 2.15.
Salicylaldehyde or 2-hydroxylnaphthaldehyde (0.5 mmol)
dissolved in dioxane (50 mL) was added instantly to the
appropriate sulfonamide drug namely; sulfamethazine,
sulfamerazine or sulfadiazine (0.5 mmol) dissolved in
dioxane/H2O mixture (50: 5 v/v) in an ultrasonic bath.
Few drops of glacial acetic acid were added to the solu-
tion and the turbid solution was further ultrasonicated at
42 KHz for a period of 1 h. The resulted colloidal solution
was extracted by centrifugal separation for 15 min at
6000 rpm and the precipitate was thoroughly washed
with water, ether and dried at 60 ꢀC for 24 h in a
vacuum oven.
2.5.4 | [Zn (HL2) 2 (OAc)2]
ꢀ
Yield 95.2%; m.p. 231 C; yellow solid. Anal. Calc. for
C40H38N8S2O10Zn (%): C, 52.3; H, 3.9; N, 12.2; S, 6.9; Zn,
7.1. Found (%): C, 52.6; H, 4.1; N, 12.4; S, 7.2; Zn, 7.0. Λm
(Ω−1mol−1cm2) = 3; FT-IR (ν, cm− 1): 1569, 1,245, 3,437,
1,158, 1,338, 1,490, 1,692, 506,439. UV–Vis (λmax, nm):
2.5 | Synthesis of metal (II) complexes
(general method)
1
260, 320, 425, HNMR: CH=N δ8.60 (s, 1H),OH δ12.65
(s, 1H disappeared with D2O),NH δ5.94(s,1H),CH3 δ2.50
(s 6H), CH3COO δ3.30(s, 6H),Pyrimidin protonδ 6.56
(m,2H),Aromatic protons δ6.60–7.98 (m, 8H).
A
warm ethanolic solution of
M
(OAc)2.nH2O
[M = Cu (II) or Zn (II), n = 1 or 2, respectively]
(2.0 mmol) was added to a (2.0 mmol) of the prepared
organic ligands HL1-HL5 in ethanol (25 mL). The mix-
ture was refluxed for 2 h and the formed precipitate
in each case was collected by filtration, washed thor-
oughly with ethanol, diethyl ether and dried at 60 ꢀC
for 24 h in a vacuum oven. The melting points of the
synthesized complexes were in the range 219 ꢀC to >
2.5.5 | [cu (L3) (OAc)]
Yield 90%; m.p. >300 ꢀC; green solid. Anal. Calc. for
C25H22N4SO5Cu (%): C, 54.2; H, 3.9; N, 10.1; S, 5.7; Cu,
11.4. Found (%): C, 54. 9; H, 4.2; N, 10.3; S, 5.9; Cu, 12.7.
Λm (Ω−1mol−1cm2) = 2; FT-IR (ν, cm−1): 3458, 1,630,
1,535, 1,451, 1,368, 1,285, 1,138, 550, 437. UV–Vis (λmax,
nm): 260, 320, 420, 690, ESR: g∥=2.27, g⊥=2.07;
<g> = 2.13.
ꢀ
300 C.
2.5.1 | [cu (L1) (OAc)]
Yield 89.2%; m.p. 219 ꢀC; brown solid. Anal. Calc. for
C21H20N4SO5Cu (%): C, 50.0; H, 3.9; N, 11.1; S, 6.3; Cu,
12.6. Found (%): C, 50. 3; H, 3.7; N, 11.4; S, 6.6; Cu, 12.7.
Λm (Ω−1mol−1cm2) = 4; FT-IR (ν, cm−1): 3398, 1,656,
1,517, 1,487, 1,340, 1,256, 1,167, 540,425. UV–Vis (λmax,
nm): 265, 360, 430, 756.ESR: g1 = 2.02, g2 = 2.22,
g3 = 2.26; Rr = 0.12; <g> = 2.18
2.5.6 | Zn[(HL3) (OAc)2].2H2O
ꢀ
Yield 89.2%; m.p. >300 C; yellow solid. Anal. Calc. for
C27H30N4SO9Zn (%): C, 49.8; H, 4.4; N, 8.6; S, 4.9; Zn,
10.0. Found (%): C, 50.1; H, 4.7; N, 8.7; S, 5.2; Zn, 10.1.
Λm (Ω−1mol−1cm2) = 3; FT-IR (ν, cm−1): 3435, 1,642,
1,538, 1,429, 1,376, 1,217, 1,139, 500, 438.UV–Vis (λmax,
nm): 260, 320, 425,1HNMR: CH=N δ9.09 (s, 1H),OH
δ9.65(s,1H disappeared with D2O), NH δ5.96(s,1H), CH3
δ2.51 (d 6H), CH3COO δ3.44(s, 6H), Pyrimidin protonδ
6.68(s,2H), Aromatic protons δ6.96–8.10 (m, 10H).
2.5.2 | [Zn (L1) 2].2H2O
Yield 90%; m.p. 240 ꢀC; yellow solid. Anal. Calc. for
C38H38N8S2O8Zn(%): C, 52.8; H, 4.4; N, 12.9; S, 7.4; Zn,
7.5. Found (%): C, 53.1; H, 4.1; N, 13.3; S, 6.6; Zn, 7.4. Λm
(Ω−1mol−1cm2) = 4; FT-IR (ν, cm−1): 3387, 1,512,
1,374,1,271, 1,140, 586,452. UV–Vis (λmax, nm): 270, 370,
430, 1HNMR: CH=N δ10.05(s, 1H), NH δ5.96 (s,1H), CH3
δ2.4 (s 6H), pyrimidin proton at δ 6.54(s,1H),aromatic
protons δ6.70–7.74 (m, 8H).
2.5.7 | [cu (L4)(OAc)].3H2O
ꢀ
Yield 96.3%; m.p. >300 C; green solid. Anal. Calc. for
C24H26N4SO7Cu (%): C, 48.5; H, 3.3; N, 9.4; S, 5.3; Cu,
10.6. Found (%): C, 52. 4; H, 4.2; N, 9.5; S, 53; Cu, 10.4.

6 of 23
EL-DISSOUKY ET AL.
Λm (Ω−1mol−1cm2) = 3; FT-IR (ν, cm−1): 3445, 1,654,
1,537, 1,431, 1,396, 1,253, 1,138, 565,462.UV–Vis (λmax,
nm): 260, 320, 420, 690.ESR: g1 = 2.06, g2 = 2.09,
g3 = 2.27; Rr = 0.85; <g> = 2.14.
strengths, f), were obtained using the Time-Dependent
Density Functional Theory (TD-DFT) at the same level of
the theory.
2.7 | Antimicrobial activity
2.5.8 | [Zn (HL4)(OAc)2].2H2O
The ligands HL1-HL5 and their copper and zinc com-
plexes were screened in-vitro against pathogenic bacteria
strains: (i) Gram-positive bacteria: Streptococcus pneumo-
nia (ATCC 49619) and Bacillus subtilis (ATCC6633),
(ii) Gram-negative bacteria: Escherichia coli (ATCC 6538)
and Pseudomonas aeruginosa (ATCC 9027) and
(iii) Fungi: Candida albicans (ATCC 10231) and Aspergil-
lus fumigatus (ATCC 46645). Ampicillin and Gentamicin
were used as standard bacteriocide while Amphotericin B
as a standard fungicide.
The antimicrobial activity of the samples was deter-
mined using the diffusion agar method.[14] All the pre-
pared compounds were dissolved to synthesize a stock
solution of 5 mg/mL in DMSO. The solution was two-fold
diluted to have solutions of various concentrations. Mea-
suring the diameters of the inhibition zone (mm) was
used to determine the antimicrobial activities. Media
with DMSO was served as control.
ꢀ
Yield 92.2%; m.p. >300 C; orange solid. Anal. Calc. for
C26H28N4SO9Zn (%): C, 49.0; H, 4.2; N, 8.7; S, 5.0; Zn,
10.5. Found (%): C, 49.3; H, 4.6; N, 9.0; S, 4.9; Zn, 10.3.
Λm (Ω−1mol−1cm2) = 3; FT-IR (ν, cm−1): 3437, 1,630,
1,539, 1,428,1,380, 1,252,1,134,586, 439.UV–Vis (λmax,
nm): 260, 320, 425,1HNMR: CH=N δ9.09 (s, 1H),OH
δ9.65(s,1H disappeared withD2O), (NH) δ5.96(s,1H),
(CH3) δ2.49 (d 3H), CH3COO δ3.44(s, 6H),Pyrimidin
protonδ 6.58(s,2H),Aromatic protons δ6.71–8.13 (m,
10H).
2.5.9 | [cu (L5) (OAc)].2H2O
Yield 92%; m.p. 290 ꢀC; green solid. Anal. Calc. for
C23H22N4SO7Cu (%): C, 49.1; H, 3.9; N, 9.9; S, 5.6; Cu,
11.3. Found (%): C, 49.4; H, 4.2; N, 10.3; S, 5.4; Cu, 11.3.
Λm (Ω−1mol−1cm2) = 3; FT-IR (ν, cm−1): 3443, 1,620,
1,539, 1,491, 1,339,1,277, 1,135, 570, 463. UV–Vis (λmax,
nm): 270, 335, 420, 690.ESR: g = 2.12.
All cultures were usually maintained on NA (nutrient
ꢀ
agar) and incubated at 37 C. The inoculums of bacteria
were performed by growing the culture in NA broth at
37 ꢀC for 24 h. Approximately, 0.1 mL of diluted bacterial
or fungal culture suspension was spread with the help of
spreader on NA plates uniformly. Solutions of the tested
compounds and reference drugs were prepared by dis-
solving 10 mg of the compound in 10 mL DMF. A
100 mL sample was pipetted into a hole (depth 3 mm)
made in the center of the agar. Sterile 8 mm discs
(Hi media Pvt. Ltd.) was impregnated with test com-
pounds. The disc was placed onto the plate and each
plate had one control disc impregnated with solvent. The
incubation of the plates was carried out at 37 ꢀC
for 18–48 h. Standard discs of Gentamicin and
Ampicillin (Antibacterial agents were; 10 mg/disc) and
Amphotericin B (Antifungal agent; 10 mg/disc) were
acted as positive controls for antimicrobial activity while
filter discs impregnated with 10 μL of solvent dimethyl
sulfoxide were served as a negative control.
2.5.10 | [Zn (L5)2]
Yield 97%; m.p. 289 ꢀC; yellow solid. Anal. Calc. for
C42H30N8S2O6Zn (%): C, 57.8; H, 3.4; N, 12.8; S, 7.3; Zn,
7.5. Found (%): C, 57.6; H, 3.7; N, 12.6; S, 7.5; Zn, 7.7. Λm
(Ω−1mol−1cm2) = 3; FT-IR (ν, cm−1): 3438, 1,537, 1,336,
1,285, 1,154, 573, 438. UV–Vis (λmax, nm): 270, 340,
1
430, HNMR: CH=N δ9.22 (s, 1H), (NH) δ5.97(s,1H),,
Pyrimidin
protonδ
6.52(d,3H),Aromatic
protons
δ6.55–8.45 (m, 10H).
2.6 | Computational methodology
Gas-phase geometries of HL1-HL5 were optimized by
.
DFT/B3LYP method[16] combined with 6–31 + G (d) basis
set[17] using the Gaussian 03 package.[18] The optimized
geometries were verified by performing frequency
calculations. Full geometry optimization was performed
to generate the optimized structures and ground-state
properties of the studied compounds. The electronic
transition properties, which include maximum excitation
wavelength (λmax) and relative intensities (oscillator
2.8 | In vitro cytotoxicity screening
The antitumor studies of HL1, [Cu(L2)(OAc)] and
[Cu(L3)(OAc)] were estimated versus three human
tumors; liver cancer (HEPG2), breast cancer (MCF7) and
colon cancer (HCT 116). Different concentrations of the

EL-DISSOUKY ET AL.
7 of 23
selected candidates were applied to determine IC50 values
using doxorubicin as a standard. The human cell lines:
Liver carcinoma cell lines (HEPG2), Breast carcinoma
cell line (MCF7) and Colon carcinoma cell line (HCT
116) were achieved from VACSERA Tissue Culture Unit.
Chemicals Used: Dimethyl sulfoxide (DMSO), crystal vio-
let and trypan blue dye were procured from sigma (ST.
Lous, Mo., USA). Fetal bovine serum, DMEM, RPMI-
1640, HEPES buffer solution, L-glutamine, gentamycin
and 0.25% Trypsin – EDTA were purchased from Lonza.
Crystal violet stain (1.0%) was prepared from 0.5% (w/v)
crystal violet and 50% ethanol, diluted with distilled
water then filtered through a Whatman filter paper No.1.
Cell lines propagation: The cell was propagated in
Dulbecco's modified Eagle's medium (DMEM) sup-
plemented with 10% heat- inactivated fetal bovine serum,
1.0% L-glutamine, HEPES buffer and 50 μg/mL gen-
triplicate. The cell cytotoxic effect of each tested com-
pound was calculated.[15,19] The inhibitory activity IC50 of
Doxorubicin, the standard drug versus the studied carci-
noma cell lines was identified under the above studied
environments.
3 | RESULTS AND DISCUSSIONS
3.1 | Synthesis and characterization
The targeted nanosized organic ligands, HL1-HL5 were
prepared by the nanoprecipitation reaction, Scheme 1, of
equimolar ratios of the aldehyde and the sulfonamide
drug namely; sulfamethazine, sulfamerazine or sulfadia-
zine in a mixture of dioxane/H2O (10: 1, V/V) under
ultrasonic conditions at 42 kHz for 1 h..
ꢀ
tamycin. The cells were kept at 37 C in a humidified
Interestingly, the desired particles were obtained as
well-separated spherical morphology, Figure 2, with some
interconnection degree. The tendency of spherical particle
formation of the prepared sulfonamide imine derivatives
could be related to the distribution stability of particles in
the reaction medium or the precipitation mechanism of
the particles.[20] The average diameter of the particles cal-
culated from SEM images based on numerous particles
selected randomly, ranges from 44–150 nm and the associ-
ation between particles was present in a larger or smaller
extent. The average diameters of sulfonamide imine
ligands prepared from sulfamethazine HL1 and HL3 were
70 nm and 100 nm; standard deviations were 5.85 and
11.69, respectively. The average diameter nanosized sul-
fonamide imine ligands prepared from sulfamerazine drug
exhibited a small average diameter compared to their
sulfamethazine counterpart. The average diameters for
HL2 and HL4 are 56 nm and 44 nm; standard deviations
are 13.60 and 7.44, respectively. Based on the obtained
results, the presence of two methyl substituents on the
pyrimidine ring increased the ligand nanosized.[21,22]
The heating ethanolic solution of hydrated metal ace-
tate (copper or zinc) with an equimolar ratio of the
appropriate organic ligands HL1–HL5 furnished the
corresponding complexes and their melting points are in
atmosphere with 5.0% CO2 and were subcultured two
times a week. Cell toxicity was monitored by determining
the effect of the test samples on cell morphology and cell
viability. Cytotoxicity evaluation using viability assay: for
cytotoxicity assay, the cells were seeded in 96-well plate
at a cell concentration of 1x104 cells per well in 100 μL of
growth medium. Fresh medium containing different con-
centrations of the test sample was added after 24 h of
seeding. Serial two-fold dilutions of the tested chemical
compound were added to confluent cell monolayers dis-
pensed into 96-well, flat-bottomed microliter plates
(Falcon, Nu, USA) using a multichannel pipette. The
microliter plates were incubated at 37 ꢀC in a humidified
incubator with 5.0% CO2 for a period of 48 h. Three wells
were used for each concentration of the test samples.
Control cells were incubated without a test sample and
with or without DMSO. The little percentage of DMSO
present in the wells (maximal 0.1) does not affect the
expꢀeriment. After incubation of the cells for 24 h at
37 C, the various concentration of the sample (50, 25,
12.5, 6.25, 3.12 and 1.56 μg) was added and the incuba-
tion was continued for 48 h and viable cells were deter-
mined by a colorimetric method. In brief, after the end of
the incubation period, media were aspirated and the crys-
tal violet solution (1.0%) was added to each well for at
least 30 min. The stain was removed, and the plates were
rinsed using tap water until all excess stain is removed.
Glacial acetic acid (30%) was then added to all wells and
mixed thoroughly, and then the absorbance of the plates
was measured after gently shaken on a Microplate reader
(TECAN, Inc.), using a test wavelength of 490 nm. All
results were corrected for background absorbance
detected in wells without added stain. Treated samples
were compared with the cell control in the absence of the
tested compounds. All experiments were carried out in
ꢀ
the range of 219–300 C. The non-electrolytic nature of
the prepared metal complexes was concluded from their
lower molar conductivity values.
3.1.1 | Geometry optimization and time-
dependent density functional theory (TD-
DFT) of the organic compounds
The fully optimized geometries of the investigated ligands
HL1-HL5 where the numbers of atoms are presented in

8 of 23
EL-DISSOUKY ET AL.
FIGURE 2 SEM images of the
nanosized sulfonamide imine ligands:
(a) HL1, (b) HL2, (c) HL3, (d) HL4,
(e) HL5
Figure 3 and their selected geometric parameters bond
lengths, bond angles and dihedral angles are listed in
Table 1. The optimized geometries of the investigated sul-
fonamide imine compounds suggest that the C-C, C-O,
C-N, S=O and S-N bond distances were found toꢀbe in
the range 1.346–1.462, 1.346–1.351, 1.301–1.424, and
the dihedral angles are in the range −119-156ꢀ, respec-
tively. The bond angles were found to be in the range
97–125 ꢀ1.437–1.438 and 1.755–1.760 A
Quantum chemical parameters of the ligands HL1-HL5
were obtained from the calculations including the ener-
gies of the HOMO and the LUMO, absolute electronega-
tivities, χ, chemical potentials, Pi, absolute hardness, η,
absolute softness, σ, global electrophilicity, ω, global
softness, S, and additional electronic charge, ΔNmax,
were calculated using the following equations (1–8) and
listed in Table 2.
The HOMO represents the electron-donating ability
of the molecule to donate electrons to appropriated
acceptor molecules with low-energy, empty molecular
orbital. The lower value of LUMO indicates the high abil-
ity of the molecule to accept electrons.[23] While, the
higher value of HOMO of the ligand, the easier is its abil-
ity to offer electrons. Furthermore, the smaller value of
the HOMO-LUMO energy gap, ΔE, the lower stability
and higher reactivity of the compound.[23] The optimized
geometry of the studied molecules, molecular frontier
orbitals, HOMO and LUMO, are visualized with Gauss-
ian view.[24,25] The charge density distribution, HOMO
and LUMO, for the free ligands HL1-HL5 are presented
in Figure 4. The dipole moment μ calculated from the
first derivative of the energy to an applied electric field,
was used to discuss and rationalize the structure.
ΔE = ELUMO −EHOMO
ðELUMO + EHOMOÞ
ð1Þ
ð2Þ
χ = −
2
ELUMO−EHOMO
η =
ð3Þ
2
1
σ =
η
ð4Þ
ð5Þ
ð6Þ
Pi = −χ
1
S =
2η

EL-DISSOUKY ET AL.
9 of 23
FIGURE 3 The fully optimized geometries of the investigated ligands HL1 HL5 and numbering of atoms by DFT/B3LYP method
Pi2
method. Frontier molecular orbitals (FMO) were per-
formed at the same level of theory. The theoretical
absorption spectra were simulated using Gaussian soft-
ware. TD-DFT results and the calculated excitation wave-
lengths of the investigated HL5 free ligands and their
assignments are displayed in Table 3. and TDDFT-
calculated electronic transitions in sulfonamide imine
ligands HL1and HL3 are displayed in Figures 5 and 6 as
representative examples.
The TD-DFT studies for the sulfonamide imine
ligand, 4-{[(1E)-(2-hydroxy-1-salicyl) methylene] amino}-
N-(4, 6)- dimethyl pyrimidine- 2-yl) benzene sulfon-
amide, (HL1), (Figure 5) and Table 4, represent six
main absorption bands at 663.67, 589.81, 469.88, 464.92,
393.00 and 390.31 nm. The calculated band at
663.67 nm arises from the transitions of π electrons from
HOMO to LUMO/LUMO+4 as relative to π (py) - π
*(saly/Azo-m/An)/π *(saly). The broad calculated band
at 589.81 nm arises from the transitions of [π (an)- π
*(An), π (saly/Azo-m/An)- π *(saly/An) and π (py)- π
*(saly/An)]from HOMO/HOMO-2/HOMO-5 to LUMO
+1/LUMO+2; the calculated band at 469.88 nm arises
from the transitions of π electrons from HOMO-1to
LUMO+6 which represents π (py)- π *(py) transition.
The broad calculated band at 464.92 nm arises from the
transitions of π electrons from HOMO/HOMO-4 to
ω =
ð7Þ
ð8Þ
2η
Pi
ΔNmax = −
η
An inspection of the results reveals that the value of ΔE
for HL1and HL2 ligands are found to be 0.1517 eV and
0.1552 eV, respectively, indicating that the HL1 ligand is
less stable and more reactive than HL2 ligand. This is
quite reasonable where the presence of the two-CH3
groups (electron-donating group) on the pyrimidine
moiety will enhance the electron density by their positive
inductive effect, revealing the co-planarity of the
molecule and thus affording a maximum resonance
via delocalization π-system. However, the value of
ΔE for HL3– HL5 ligands increases in the order
HL3 > HL4 > HL5 leading to the opposite effect. Addi-
,
tionally, the higher HOMO energy value of HL5
compared to HL3and HL4 indicated its high ability to
offer electrons and its lower LUMO energy value
indicated its high ability to accept electrons.[23]
To gain detailed insight into the charge transitions,
the theoretical electronic spectra were calculated by using
time-dependent density functional theory (TD-DFT)

10 of 23
EL-DISSOUKY ET AL.
TABLE 1 Selected calculated bond lengths (Ao), bond angles (o) and dihedral angles(o) for sulfonamide imine ligands
Sulfonamide imine ligands
Bond length (Ao)
C(3)-C(4)
HL1
HL2
HL3
HL4
HL5
1.418
1.418
1.447
1.447
1.447
C(4)-C(5)
1.414
1.414
1.400
1.400
1.400
C(4)-C(8)
1.462
1.461
1.456
1.456
1.455
C(5)-O(7)
1.351
1.351
1.346
1.346
1.346
C(8)-N(9)
1.301
1.301
1.306
1.306
1.306
N(9)-C(10)
1.424
1.423
1.423
1.423
1.422
S(16)-O(17)
1.438
1.438
1.438
1.438
1.437
S(16)-O(18)
1.438
1.438
1.438
1.438
1.437
S(16)-N(19)
1.755
1.757
1.756
1.756
1.760
N(19)-C(20)
1.394
1.393
1.394
1.394
1.392
C(20)-N(21)
1.383
1.385
1.383
1.383
1.386
Bond Angle (o)
HL1
HL2
HL3
HL4
HL5
C(8)-N(9)-C(10)
123.91
125.029
120.351
108.756
108.630
97.015
121.644
118.414
HL1
123.970
125.040
120.368
108.885
108.759
97.068
121.673
118.589
HL2
123.590
125.474
120.334
108.825
108.667
97.008
121.679
118.405
HL3
123.627
125.483
120.351
108.954
108.797
97.061
121.717
118.581
HL4
123.665
125.487
120.369
109.087
108.928
97.112
121.911
118.461
HL5
C(4)-C(5)-O(7)
C(4)-C(8)-N-(9)
C(13)-S(16)-O(17)
C(13)-S(16)-O(18)
C(13)-S(16)-N(19)
S(16)-N(19)-C(20)
N(19)-C(20)-N(21)
Dihedral angle(o)
C(8) -N(9) -C(10) -C(11)
C(13) -S(16)-O(18)- C(12)
-C(13) -S(16) -O(17) C(12)
C(13) -S(16) -N(19) -C(12)
C(23)- C(24) -C(26) -H40)
C(23) -C(24)- C(26)- H(41)
C(23)- C(24)-C(26)- H(42)
C(21)- C(22)- C(27)-H(43)
C(21)- C(22)- C(27)-H(45)
C(21)- C(22)-C(31)- H(49)
C(21)- C(22)- C(31)- H(51)
−66.433
21.347
156.371
−91.117
60.114
−60.353
-----------
120.175
−119.861
---------
---------
−66.908
21.288
156.523
−91.073
−60.353
----------
60.142
---------
----------
----------
---------
−57.621
21.352
156.433
−91.076
----------
---------
60.065
−60.450
---------
119.995
−120.041
−57.707
21.277
156.573
−91.043
--------
-------
−58.014
20.991
156.764
−91.093
-------
-------
60.071
−60.427
---------
--------
-------
------
-------
------
------
------
1.437-1.438 and 1.755-1.760 Aꢀ, respectively. The bond angles were found to be in the range 97-125 ꢀ and the dihedral angles are in the range
-119-156ꢀ.
LUMO+4 [π (saly/Azo-m/An) or π (py)- π *(saly). The
highest energy broad calculated band at 393.00 nm
The TD-DFT studies of the free ligand (4-{[(1E)-
(2-hydroxy-1-naphthyl) methylene] amino}-N-(4, 6)-
dimethyl pyrimidine- 2-yl) benzene sulfonamide) HL3,
ligand Figure 6 and Table 3, imply six main absorption
bands at 797.51, 597.32, 548.90, 469.86, 422.22 and
411.12 nm. The calculated band at 797.51 nm arising
from transitions of π electrons corresponds from HOMO
to LUMO as relative to π (naph)- π *(naph/Azo-m/An).
The calculated band at 597.32 nm arises from transitions
arises from the transitions of
π electrons from
HOMO/HOMO- 2 to LUMO/LUMO+7 [π (saly/Azo-
m/An)- π *(saly/Azo-m/An) and π (py)- π *(saly/Azo-
m)],the broad calculated band at 390.31 nm arises from
transitions of π electrons from HOMO/HOMO-4 to
LUMO which refers to [π (saly/Azo-m/An) or π (py)-π
*(saly/Azo-m/An)].

EL-DISSOUKY ET AL.
11 of 23
FIGURE 4 Molecular frontier orbitals HOMO and LUMO of sulfonamide imine ligands HL1-HL5
TABLE 2 The calculated quantum chemical parameters for sulfonamide imine compounds HL1-HL5
EHOMO
Molecule (eV)
ELUMO
(eV)
ΔE
(eV)
μ
(D)
E tot
(AU)
X
(eV)
ŋ
(eV)
ơ
Pi
S
ω
ΔN
(eV)-1 (eV)
(eV)-1 (eV)
max
0.171 2.121
0.171 2.101
0.183 2.292
0.184 2.295
0.186 2.313
HL1
HL2
HL3
HL4
HL5
−0.2368
−0.2411
−0.2295
−0.2300
−0.2307
−0.0851
−0.0859
−0.0899
−0.0906
−0.0915
0.1517
0.1552
0.1396
0.1394
0.1393
3.436 − 1577.705 0.1609 0.0759 13.184 −0.161 6.591
3.454 − 1538.383 0.1635 0.0776 12.886 −0.163 6.443
3.991 − 1731.349 0.1597 0.0698 14.326 −0.160 7.163
4.023 − 1692.026 0.1603 0.0697 14.347 −0.160 7.174
4.740 − 1652.703 0.1611 0.0696 14.367 −0.161 7.179
from HOMO/HOMO-3 to LUMO+1 of [π (naph/Azo-
m/An)- π *(naph/Azo-m/An)]; the calculated band at
548.90 nm arises from the transitions of π electrons from
HOMO to LUMO/LUMO+6 which represent [π (naph)- π
*(naph/Azo-m/An)/π *(Azo-m/An)]. The calculated band
at 469.86 nm arises from transitions of π electrons from
HOMO-9 to LUMO+4 [π (py) - π *(py)]. The calculated
band at 422.22 nm arises from transitions of π electrons
from HOMO/HOMO-2 to LUMO/LUMO+2 [π
(naph/Azo-m/An) - π *(naph/Azo-m/An) and π (naph)-π
*(naph)] The highest energy calculated band at
411.12 nm arises from transitions of HOMO to LUMO+8
[π (naph)- π *(naph/Azo-m)].
3.1.2 | FTIR spectra of HL1-HL5 and their
complexes
The υ (C=N) azomethine band for HL1–HL5 is located at
1595, 1594, 1,589, 1,570 and 1,581 cm−1, respectively. The

12 of 23
EL-DISSOUKY ET AL.
TABLE 3 Calculated triplet excitation energies, wave lengths, and their contributions for the sulfonamide imine ligands
Excitation energy (eV)
Wave length (nm)
Contributions
HL1
1.8682
2.1021
663.67
589.81
HOMO-LUMO, HOMO!LUMO+4
HOMO-5 ! LUMO+2,
HOMO-2 ! LUMO+1, HOMO !
LUMO+1
2.6386
2.6668
469.88
464.92
HOMO-1 ! LUMO+6
HOMO-4 ! LUMO+4, HOMO !
LUMO+4
3.1548
393.00
390.31
HOMO-2 ! LUMO, HOMO ! LUMO
+7
3.1766
HL2
HOMO-4 ! LUMO, HOMO ! LUMO
1.8687
2.1027
663.49
589.64
HOMO ! LUMO, HOMO ! LUMO+4
HOMO-5 ! LUMO+2,
HOMO-2 ! LUMO+2
2.6328
2.6670
3.1552
3.1759
HL3
470.92
464.88
392.95
390.39
HOMO-1 ! LUMO+6
HOMO ! LUMO+4
HOMO-2 ! LUMO
HOMO-4 ! LUMO, HOMO! LUMO
1.5546
2.0757
797.51
597.32
HOMO ! LUMO
HOMO-3 ! LUMO+1, HOMO !
LUMO+1
2.2588
2.6388
2.9365
548.90
469.86
422.22
HOMO ! LUMO, HOMO ! LUMO+6
HOMO-9 ! LUMO+4
HOMO-2 ! LUMO, HOMO ! LUMO
+2
3.0158
HL4
411.12
HOMO ! LUMO+8
1.5548
2.0763
797.42
597.13
HOMO ! LUMO
HOMO-3 ! LUMO+1, HOMO !
LUMO
2.2584
2.6328
2.9363
548.99
470.93
422.24
HOMO ! LUMO+6
HOMO-1 ! LUMO+7
HOMO-2 ! LUMO, HOMO ! LUMO
+2
3.0165
411.03
HOMO ! LUMO+2, HOMO !LUMO
+8
HL5
1.5549
2.0776
2.2579
2.6082
2.9364
797.36
596.76
549.12
475.37
422.24
HOMO ! LUMO
HOMO ! LUMO+1
HOMO ! LUMO, HOMO ! LUMO+6
HOMO-2 ! LUMO+7
HOMO-1 ! LUMO, HOMO ! LUMO
+3
2.9364
410.95
HOMO-1 ! LUMO

EL-DISSOUKY ET AL.
13 of 23
FIGURE 5 TD-DFT calculated electronic transitions in sulfonamide imine 4-{[(1E)- (2-hydroxy-1-salicyl) methylene] amino}-N-(4, 6)-
dimethyl pyrimidine-2-yl) benzene sulfonamide, (HL1)
difference in stretching vibration of the azomethine
group may be due to the steric and/or electronic effect of
the substituents on the aromatic rings. The spectra of
HL1–HL5 exhibit broadbands at 3393, 3436, 3,444, 3,461
and 3,456 cm−1, respectively, due to υ (OH) and υ
(NH) of the sulfonamide groups. The broad nature and
the low-frequency position of these bands could be taken
as a proof for the involvement of these two groups in
intra- and/or intermolecular hydrogen bonding. The
hydroxyl and the azomethine groups are oriented to form
hydrogen bond of intramolecular type (O-H----N=C) for-
ming a stable six-membered while the sulfonamide
(NH) group and its adjacent -SO2 and/or pyrimidine
nitrogen are not in positions to form stable intramolecu-
lar hydrogen bonding but maybe participated in an inter-
molecular hydrogen bonding of the type (N-H … O=S=O
… N-H). The FT-IR spectra of the free ligands displayed
two bands at 1310–1340 cm−1 and 1,149–1,155 cm−1 due
to υ (SO2)asym and υ (SO2)sym, respectively. Furthermore,
the spectra of the ligands displayed a medium-strong
band in the range 1,238–1,261 cm−1, due to phenolic υ(C-
O) confirming the participation of the phenolic OH in H-
bonding.[26] Furthermore, the ligands exhibited the
pyrimidine υ (C=N) at 1513–1567 cm−1 as only one strong-
medium band suggesting that the two C=N groups in the
pyrimidine moiety are equivalent. Generally, the FT-IR
spectra of the Cu (II) and Zn (II) complexes displayed a
medium-strong band at 1512–1569 cm−1 due to υ
(C=N)azomethine compared to that of the ligands that
found at 1570–1595 cm−1. The lower shift of υ(C=N)
ranging from 58 to 26 cm−1 on chelation indicated the
coordination of the azomethine nitrogen to the metal
ion.[27] The spectra of the metal (II) complexes displayed
a band at 1520–1554 cm−1 due to υ (C=N)Pyrimidine simi-
lar to that of the ligands suggesting a non-bonding nature
of the pyrimidine nitrogen atoms. The characteristic band
of υ(C-O)phenolic was upward shifted by 15–24 cm−1 in
copper complexes, [Zn(L1)2].2H2O and [Zn(L5)2] con-
firming the coordination of the deprotonated phenolic-
OH, whereas no appreciable shift of this specific band
was noticed in the case of [Zn (HL2)2(OAc)2], [Zn (HL3)
(OAc)2].2H2O and [Zn (HL4)(OAc)2].2H2O indicating the
bonding of the phenolic OH to the metal ion.
All copper complexes exhibited new medium bands
at υ 1,607–1,656 cm−1 and 1,410–1,491 cm−1 assignable
to υasym (COO−) and υsym (COO−), respectively. The

14 of 23
EL-DISSOUKY ET AL.
FIGURE 6 TD-DFT calculated electronic transitions in sulfonamide imine 4-{[(1E)- (2-hydroxy-1-naphthyl) methylene] amino}-N-
(4, 6)- dimethyl pyrimidine- 2-yl) benzene sulfonamide, (HL3)
magnitude of separation (Δυ = υasym–υsym) is in the
range of 165–197 cm−1 in all complexes except for
[Zn (HL3)(OAc)2].2H2O and [Zn (HL4)(OAc)2].2H2O
which suggests the bidentate coordination of the acetate
group.[28] The value of Δυ = 202 cm−1 in the case of
[Zn (HL3)(OAc)2].2H2O and [Zn (HL4)(OAc)2].2H2O
confirmed the monodentate nature of the acetate
group.[28] All complexes displayed medium broad bands
at 3200–3500 cm−1 characteristic to ν (NH) and ν
(OH) and bands at 500–586 and υ 425–462 cm−1 related
to ν (M–N) and ν (M–O), respectively, supporting the
coordination to the ligands.[27]
3.1.3 | Electronic spectra
The electronic spectra of the organic ligands and their Cu
(II) and Zn (II), complexes were recorded as 10−5
M
DMSO solution in the wavelength range of
200–1,000 nm. The spectra of HL1–HL5 showed high
intense bands at 260–270, 320–355 and 415–475 nm due
to the intra- ligand π ! π*, n ! π* and charge transfer
transitions, respectively, and rather consistent with the
literature data.[29] The [Cu(L2)(OAc)].nH2O, [Cu(L3)
(OAc)].H2O,
[Cu(L4)(OAc)].3H2O,
and
[Cu(L5)
(OAc)].2H2O exhibited broad bands at λ 690–700 nm

EL-DISSOUKY ET AL.
15 of 23
TABLE 4 Thermal analyses of sulfonamide imine ligands and their metal (II) complexes
Mass loss (%) Found
Compound No.
HL 1
Steps TG (ꢀC) DTG (ꢀC)
(Calculated)
24.37(24.34)
75.625(75.65)
11.73(11.71)
5.43(5.36)
Fragment
DTA (ꢀC)
I
250–457
457–800
80–121
325
575
80
C6H5O
87.1(Endo.)
II
I
C13H13SO2N4 530(Exo.)
[Cu(L 1 ) (OAc)]
C2H3O2
CHN
81.4(Endo.)
361.3(Exo.)
II
III
IV
121–177
177–310
310–550
Residue
80–144
150
260
360
27.82(27.80)
42.39(42.50)
12.60(12.61)
4.17(4.16)
C6H4O2S
C12H12ON3
Cu
---
[Zn (L 1
)
2 ].2H 2
O
I
90
2H2O
94.7(Endo.)
II
III
144–344
344–580
Residue
80–300
224
570
42.33(42.27)
44.07(44.12)
9.41(9.42)
C19H17O2SN4 463and572.2(Exo)
C19H17O3SN4
ZnO
---
HL 2
[Cu (L 2 )(OAc)]
I
85
25.25(25.27)
74.74(74.72)
12.05(12.05)
5.52(5.51)
C6H5O
89.7(Endo.)
II
I
300–650
80–120
305and550
85
C12H11O2N4S 527.1(Exo.)
C2H3O2
CHN
84(Endo.)
476(Exo.)
I
120–185
185–280
280–490
Residue
84–260
135
III
IV
230
28.63(28.06)
40.87(40.85)
12.91(12.97)
11.11(10.87)
40.02(40.02)
40.06(40.02)
8.79(8.85)
C6H4O2S
C11H10ON3
Cu
340and470
---
[Zn (HL 2
)
2 (OAc) 2
]
I
150
425
560
C4H6O3
84(Endo.)
II
III
260–505
505–670
Residue
220–370
370–454
454–765
80–217
C18H16O3SN4 427.3(Exo.)
C18H16O3SN4 560.6(Exo.)
ZnO
---
HL 3
I
295
416
570
150
340
478
35.89(35.87)
6.32(6.25)
C6H5O2SN
CHN
103.2(Endo.)
540.1(Exo.)
II
III
I
57.77(57.87)
10.69(10.65)
30.59(30.53)
47.18(47.33)
11.52(11.47)
5.55(5.52)
C22H18ON2
C2H3O2
C11H7NO
C12H12O2N3S
Cu
[Cu (L 3 )(OAc)]
112.9(Endo.)
473.3(Exo.)
II
III
217–397
397–572
Residue
80–115
---
[Zn (HL 3 )(OAc) 2 ].2H 2
O
I
85
2H2O
86.1(Endo.)
568.6(Exo.)
II
III
IV
I
115–360
360–640
Residue
135–419
419–755
80–155
250
15.68(15.65)
66.25(66.31)
12.51(12.49)
36.98(37.08)
63.01(62.91)
19.12(19.03)
23.94(23.92)
46.22(46.67)
10.70(10.69)
5.677(5.64)
16.03(16.00)
C4H6O3
C23H20N4SO3
ZnO
425and590
---
HL 4
[Cu (L 4 )(OAc)].3H 2
295
C6H5O2SN
C16H13ON3
C2H9O5
C10H6O
C12H11N4SO
Cu
94.9(Endo.)
568.9(Exo.)
82.6(Endo.)
311.9(Exo.)
II
I
575
O
150
II
III
155–295
295–487
Residue
80–100
230
305and435
---
[Zn (HL 4 )(OAc) 2 ].2H 2
O
I
85
2H2O
82.3(Endo.)
558.6(Exo.)
II
III
100–210
210–647
165
C4H6O3
C22H18N4SO3
340,456and555 65.52(65.57)
(Continues)

16 of 23
EL-DISSOUKY ET AL.
TABLE 4 (Continued)
Compound No.
Mass loss (%) Found
(Calculated)
Steps TG (ꢀC) DTG (ꢀC)
Fragment
DTA (ꢀC)
Residue
12.77(12.77)
ZnO
---
HL 5
I
180–430
430–763
80–176
320
560
95
38.33(38.36)
61.44(61.63)
16.96(16.91)
25.32(25.28)
46.39(46.48)
11.31(11.30)
44.41(44.41)
46.27(46.24)
9.31(9.34)
C6H5O2SN
C15H11ON3
C2H7O4
117.4(Endo.)
544.9(Exo.)
81.6(Endo.)
489.7(Exo.)
II
I
[Cu(L 5 )(OAc)].2H 2
O
II
III
176–410
410–650
Residue
79–260
312
490
C10H6O
C11H9O2N4S
Cu
---
[Zn (L 5
)
]
I
165
C20H14O3N3S 79.7(Endo.)
C20H14O4N3S 589.3(Exo.)
2
II
260–644
Residue
330and590
ZnO
---
2
referred to B1g
tetragonally
!
2B2g transition corresponding to a
transfer. It has been reported that in a highly polar sol-
vent as DMSO, the enolic tautomer could be present in
more than one form.[32] The enol tautomer could be
observed as a resonance hybrid of two canonical struc-
tures, the quinoid and/or zwitterionic forms, Figure 7. In
general, polar solvents shifted the enol-keto equilibrium
towards the enolic form.[33,34] The solvent protonates the
imino bond-forming several possible intermediates
including a zwitterionic form which favor molecular
polarity and thus, the electrostatic intermolecular inter-
actions become stronger. The keto-amine tautomer could
be either cis or trans relative to the C=N bond.[35]
distorted
copper
(II)
complexes
ion.[30,31] The spectrum of [Cu(L1)(OAc)] showed solely a
single broadband at 765 nm consistent with tetragonally
distorted
or
trigonal
bipyramidal
copper
geometry.[30] The UV–Vis spectra of zinc complexes did
not exhibit a d-d transitional band characteristic of d10
species. Furthermore, their spectral bands are nearly sim-
ilar to their precursor ligands with red or blue shifts.
According to the empirical formula supported by other
data such as elemental analysis and spectroscopic data, a
tetrahedral geometry for all Zn (II) complexes was pro-
posed, except [Zn (HL2)2(OAc)2] complex where octahe-
dral geometry was estimated.
1
The H-NMR spectra of the prepared organic ligands
HL2 HL5 showed broad singlet signal at
δ11.77-δ11.82 ppm corresponding to the deuteratable
OH. The two singlet signals at δ10.14 and 10.13 ppm in
the spectrum of HL2 and δ9.65 and 9.64 ppm in the spec-
trum of HL3 corresponded to azomethine proton. How-
ever, the HC=N proton appeared at δ 9.57 and 9.59 ppm
in the spectrum of HL4 and HL5 respectively. The aro-
matic protons resonated at δ 8.86–6.55 ppm. The spec-
trum of HL2 exhibited methyl protons at δ2.27 (s, 3H,
major) and δ 2.29 (s, 3H, minor). In a similar fashion, the
spectrum of HL3 displayed a singlet at δ δ 2.23 (s, 3H,
major) and δ 2.20 (s, 3H, CH3, minor) assignable to
1
3.1.4 | H NMR spectra of the ligands and
their Zn (II) complexes
The 1H-NMR spectra of the sulfonamide imines HL1-
HL5 were performed in DMSO-d6. The H-NMR spec-
1
trum of HL1, is given in the supporting information
(Figure S1), was selected as a representative example.
Four isomers in (8:5:2:1) ratio were easily identified by
the presence of four CH3 protons signals according to
their relative abundance at δ 2.23 ppm, 2.20 ppm,
2.28 ppm and 2.26 ppm, respectively. The singlet signal
of the azomethine proton of the isomeric mixture reso-
nated at δ 8.93 ppm, δ 8.90 ppm, δ 8.89 ppm while that
belongs to the minor isomer could be buried under other
signals. The deuteratable broad singlet signal at δ
5.21 ppm was attributed to the NH proton. The aromatic
protons appeared subsequently as multiplet signals. The
presence of such isomers was attributed to enolimine-
ketoamine tautomerism by intramolecular proton
1
methyl protons. Analogously the H-NMR spectrum of
HL4 recorded a methyl signal at δ 2.32 (s, 3H, CH3).
Zinc (II) complexes exhibited similar singlet at δ
10.05–8.60 ppm, assigned to azomethine (-CH=N)
proton. This specific proton resonated relatively at a
lower field than that of the ligand (Δδ = +1.07
to 0.27 ppm) indicating azomethine's nitrogen-Zn
(II) coordination. The absence of phenolic-OH signal in
the case of [Zn(L1)2].2H2O and [Zn(L5)2] confirmed
its deprotonation upon complexation. The spectra of

EL-DISSOUKY ET AL.
17 of 23
FIGURE 7 Enolimine-ketoamine tautomerism of HL1 in DMSO-d6
[Zn (HL2)2(OAc)2], [Zn (HL3)(OAc)2].2H2O and
[Zn (HL4)(OAc)2] .2H2O exhibited abroad and low-
intensity signal at δ 12.65, 9.65, 9.65 ppm, respectively,
due to the phenolic-OH. Relative to the parent ligand,
the latter signal was downfield shifted by (Δδ = 0 to +
0.13 ppm). This signal disappeared in the presence of
D2O and its broadness and low intensity could be consid-
ered as an evidence for bonding of the oxygen atom of
the deprotonated and non-ionized phenolic group to the
zinc (II) ion.[36] The [Zn (HL2)2(OAc)2], [Zn (HL3)
(OAc)2].2H2O and [Zn (HL4)(OAc)2].2H2O complexes
exhibited new signals at δ 3.30, 3.44 and 3.49 ppm,
respectively, assignable to Zn (II) coordination. Methyl
of g3 > g2 > g1 with gav = 2.18, 2.15 and 2.14, respec-
tively, demonstrating that the unpaired electron presents
2
2
mainly in dx -y ground state confirming elongated
tetragonally distorted copper geometry. Moreover, the R
values, indicated the distortion towards symmetry of
2
2
2
2
mixed dx -y and dz states with increasing dz predomi-
nance in their ground states than dx -y2. The spectrum of
2
the polycrystalline sample [Cu(L3)(OAc)] displayed axial
parameters g (2.27) > g⊥( 2.07)>ge (2.0023) indicating
k
2
2
dx -y ground state, and the latter was further confirmed
by the 2.13 average g-value. The value of G- parameter,
3.80, indicated a negligible or very small direct Cu-Cu
interaction in the solid-state and intermediate ligand
field. In the parallel region, the spectrum displayed a
hyperfine structure owing to the coupling of the nuclear
spin (I = 3/2) of both copper isotopes 65Cu and 63Cu
with the unpaired electron. The appearance of the paral-
lel hyperfine revealed a covalent Cu-ligand bond. On the
other hand, no splitting was observed in the g┴ region
owing to the unresolved ligand hyperfine interaction at
room temperature. As appeared from the spectrum, the
hyperfine line splitting factor of 103G agrees with distor-
tion from planarity. The tetragonal distortion was
substituents in zinc complexes appeared at
δ
2.40–2.51 ppm, whereas the sulfonamide (SO2NH) proton
resonated at δ 5.94–5.97 ppm and the signal disappeared
with D2O. The pyrimidine proton(s) signal appeared at δ
6.68–6.25 ppm. Other aromatic protons appeared at δ
6.55–8.54 ppm without coordination to the zinc ion as
predicted from their chemical shifts.
3.1.5 | EPR spectra
deduced from the empirical factor
ƒ
=
g
/A
k
k
The X-band EPR parameters of [Cu(L1)(OAc)], [Cu(L2)
(OAc)] and [Cu(L4)(OAc)].3H2O showed rhombic nature
(220 cm−1), in general, the value of ƒ ≥ 150 cm−1 rev-
ealed a strong distortion ascribed to the flexible structure

18 of 23
EL-DISSOUKY ET AL.
and/or bulkiness effect of the ligand. The planarity dis-
tortion towards the tetragonally distorted tetrahedral or
steps. The proposed fragments for the degradation steps
are compiled in Table 4 All copper complexes displayed
two endothermic and exothermic DTA peaks and
the heat capacity values were calculated from the DSC
curves, curves given in the supporting information
(Table S2).
octahedral structure decreased A and increased g as
k
k
exemplified in many synthetic and biologically active
copper compounds.[36,37]
Based on equation (9) the in-planar π bonding param-
eter α2 was calculated to be 0.57 which agrees with cova-
lent Cu-in-plane-ligand bonding and is inconsistent with
The
TGA/DTA
curves
of
[Zn(L1)]2.2H2O,
[Zn (HL2)2(OAc)2], [Zn (HL3)(OAc)2].2H2O and
[Zn (HL4)(OAc)2].2H2O complexes, as shown in the
supporting information (Figure S3), exhibited three
decomposition steps, while, on the other hand, [Zn(L5)2]
complex displayed degradation within two steps. The
residual decomposition products in all zinc complexes
were ZnO as remains. The DTA curve of [Zn(L1)]2.2H2O
and [Zn (HL2)2(OAc)2] complexes showed two endother-
mic peaks and one exothermic peak, however, other com-
plexes of HL3-HL5 displayed an endothermic and an
exothermic peak. The heat capacity for the zinc com-
plexes was calculated from the DSC curve. The thermal
studies of the synthesized complexes from their curves
were in good agreement with their proposed structures
and their molecular formula.
the value of g < 2.30.
k
ꢀ
ꢁ
À
Á
α2 = A =0:036 + g −2:0023 + 3=7 g┴ – 2:0023 + 0:04
k
k
ð9Þ
The room temperature X-band EPR spectrum of [Cu(L5)
(OAc)].2H2O showed an isotropic intense absorption
band in the high field due to the tumbling motion of mol-
ecules[38] and the line width estimated from the spectrum
Δpeak-peak = 191 G. The gi = 2.12 region indicated a
dipole–dipole and weak exchange interactions between
Cu (II) centers. The complex has low g-value signifying
more covalent polar bonding. The g-value of 2.12 (>
2.0023 for the free electron) indicated the location of the
The thermodynamic parameters of decomposition
namely, activation energy (Ea), enthalpy change (ΔH),
entropy change (ΔS) were evaluated by employing the
Horowitz-Metzger equation,[40] and given in the
supporting information (Table S2). The chemical reac-
tion order (n) and the value of the decomposed sub-
stance fraction (αm) were calculated utilizing the
Kissinger method.[41] The values of collision factor
(Z) was obtained using Horowitz-Metzger equation
(10),[40]
2
unpaired electron predominantly in the dx -y2 orbital gro-
und state. In general, the spectrum is consistent with the
tetragonally distorted species with coordination number
4, in agreement with the literature data for distorted
square planar copper complexes.[39]
3.1.6 | Thermal studies
Thermal analysis, Table 4, of the ligands and their com-
plexes were studied utilizing thermogravimetric analysis
(TGA), derivative thermogravimetric analysis (DTG), dif-
ferential thermal analysis (DTA) and differential scan-
ning calorimetric (DSC) methods in a stream of nitrogen
and the results are compiled in the supporting informa-
tion (Table S2). Furthermore, the % weight losses during
decomposition steps are summarized and estimated in
terms of the molecular formula. The TGA profiles and
data of the ligands HL1–HL5 showed two main decompo-
sition steps except for HL3 which display three successive
decomposition steps where each one displays maximum
DTG peaks at which the degradation temperature
occurred. The gradual degradation of ligands was accom-
panied by successive endothermic and exothermic DTA
peaks and the heat capacity was calculated from the DSC
curve.
ꢂ
ꢃ
ꢂ
ꢃ
Ea
Ea
RT2m
KTm
h
ΔS
R
Z =
ϕ exp
=
exp
ð10Þ
RTm
where (ΔS) is the entropy of activation, (R) represents
molar gas constant, (ϕ) rate of heating (K S−1), (K) the
Boltzmann constant, and (h) the Planck's constant.[42]
The change in enthalpy (ΔH) for any phase proceeding at
any peak temperature (Tm), was determined from the
relation (ΔS = ΔH/T). Considering, the least square cal-
culations, the lnT against 1,000/T plots for all complexes,
for DTA curve, gave straight lines from which the activa-
tion energies are calculated according to the stated
method.[42] The slope is of Arrhenius type and equals to
(− Ea/R).
The heat capacity (Cp) could be calculated from the
The TGA profile of the copper complexes [Cu(L1)
(OAc)] and [Cu(L2)(OAc)] proceeded in four degradation
steps while [Cu(L3)(OAc)], [Cu(L4)(OAc)].3H2O and
[Cu(L5)(OAc)].2H2O decomposed in three successive
relation (11):
Q
Cp =
ð11Þ
ΔT

EL-DISSOUKY ET AL.
19 of 23
where (Cp) is the heat capacity in (mJ.g−1 K−1) and (Q) is
the amount of heat energy or heat flow per unit of time
(mJ/sec) and (ΔT) is the temperature differences between
the onset and the offset of the endothermic and exother-
mic peaks. The calculated heat capacity values are col-
lected in the supporting information (Table S2).
Based on the thermal results, the following points are
concluded:
exhibited potent activity versus Gram-negative bacteria
and the growth inhibition zone diameters were 22.6 mm
(E. Coli), 18.3 mm (P.Aeruginosa). Interestingly, the inhi-
bition zone diameters are higher than those obtained by
the standard bacteriocide Gentamicin.
As reported in the literature, the discovery of potent
antitumor candidates depends basically on the line of
antibiotics affecting Gram-negative bacteria.[43,44] The
membrane of these bacteria is surrounded by a lipopoly-
saccharides outer membrane which allows lipid-soluble
materials passage. It is clear that HL1 combined with the
lipophilic layer via charge transfer interaction and thus,
enhanced the membrane permeability of the Gram-
negative bacteria and it restricted further growth of the
organisms.[45] HL2 exhibited potent activity against
Gram-positive bacteria like Gentamicin and Ampicillin;
the standard bactericides in use. HL3 and HL4 virtually
lack any noticeable antibacterial activity, while HL5
showed moderate activity against B. subtilis and
S. pneumonia, low activity against E. Coli and inactive
against P. aeruginosa. Concerning structure–activity cor-
relation, it may be concluded that imines based
salicylaldehyde exhibited higher activity than those
derived from 2-hydroxynaphth- aldehyde.
Antibacterial activities of Cu (II) and Zn
(II) complexes are given in Table 5. It is obvious that cop-
per complexes are more active than zinc complexes.
Noteworthy, [Cu(L1)(OAc)] displayed a higher inhibition
zone against S. pneumoniae and B. subtilis than the pre-
cursor ligand HL1. On the other hand, [Cu(L2)(OAc)]
exerted equal inhibition zone diameters as the standard
bacteriocides in use. Analogously, [Cu(L3)(OAc)]
exhibited high activity against B. subtilis and it was also
performed an inhibition zone diameter greater than
Ampicillin.
• The calculated values of the collision number (Z) in
each case exhibited a direct relation to (Ea). Both maxi-
mum and minimum (Z) values were 3.84 and 0.109,
respectively, indicating variable mechanisms at differ-
ent speeds.
• At the maximum development of the reaction in each
step, the values of the decomposed fraction (αm) have
the same magnitude ranging from 0.72 to 0.40 within
the melting temperature (Tm) range 862.3–352.7 K.
• The entropy change (ΔS) for all compounds is in the
range of - 0.239 to - 0.271 kJK−1 mol−1 indicating
ordered transition states in less random molecular con-
figurations than the complexes.
• The fraction values of the order of the reaction
(n) suggested either incomplete reaction or its proceeds
in a complicated mechanism.
The activation energies (Ea) of Cu (II) complexes are
lower than that of Zn (II) complexes. The order is by the
rule stated that: the activation energy (Ea) of the complex
increases as the metal ion radius decreased
(Zn (II) = 88 pm < r Cu (II) = 91 pm). The trend of the
−1
calculated (Ea, kJmol ) of the complexes using
Horowitz-Metzger method at the first decomposition step
is in the following order:
[Zn (L1)2].2H2O = 28.406 > [Cu(L1) (OAc)] = 27.345,
[Zn (HL2)2(OAc)2] = 61.414 > [Cu(L2)(OAc)] = 41.911,
Remarkably, all zinc complexes exhibited no activity
only against Pseudomonas aeruginosa. Concerning metal-
activity correlation, it was noticed that [Cu(L2)(OAc)],
[Cu(L3) (OAc)], [Zn (HL3)(OAc)2].2H2O and [Zn (HL4)
OAc)2].2H2O exerted higher activity compared to their
ligands. In contrary, HL5 exhibited a better activity
against all bacteria strains than its complexes. it was con-
cluded that metal chelates enhanced the biological activ-
ity and this behavior could be explained in terms of
azomethine H-bonding with various active cellular con-
stituents that produce interference with normal cellular
processes.[46]
[Zn (HL3)(OAc)2].2H2O
=
36.117
>
[Cu(L3)
(OAc)] = 28.644,[Zn (HL4)(OAc)2].2H2O = 60.951 > [Cu
(L4)(OAc)].3H2O = 41.564, [Zn(L5)2] = 33.688 > [Cu(L5)
(OAc)].2H2O = 32.296.
• The negative (ΔH) values indicate an exothermic
decomposition process.
• The heat capacity (Cp) of the dehydration process of
the hydrated complexes is nearly similar and equals to
272.9 mJg−1 K−1.
The data of the antifungal activity of HL1-HL5 and
their metal (II) complexes are collected in Table 5 and
(in the supporting information Figure S4). It was shown
that: (i) the free ligands displayed appreciable antifungal
activity in the order: HL2 > HL1 > HL5 > HL4 > HL3.
(ii) the [Cu(L3)(OAc)] complex showed high potency
3.2 | Antimicrobial evaluation
The antimicrobial screening data Table 5, are represented
graphically, in the supporting information (Figure S4).
Results indicated that among the tested ligands, HL1

20 of 23
EL-DISSOUKY ET AL.
TABLE 5 Antimicrobial screening results of sulfonamide imine ligands and their Cu (II) and Zn (II) complexes
Inhibition zone diameter (mm/mg sample)
Compound
E. Coli
ATCC
6538
(Gram negative bacteria)
P. Aeruginosa
ATCC 9027
S. Pneumoniae
ATCC 49619
B. subtilis
ATCC 6633
C. albicans
ATCC 10231
A. fumigatus
ATCC 46645
(Gram positive bacteria)
(Fungi)
Gentamicin(G-)
Ampicillin (G+)
Amphotericin B
Control: DMSO
HL1
[Cu(L1) (OAc)]
[Zn (L1)2].2H2O
HL2
19.9
17.3
23.8
32.4
25.4
Nil
23.7
Nil
Nil
Nil
Nil
Nil
22.6
20.3
11.9
19.9
19.9
10.8
18.3
NA
NA
17.3
17.3
NA
16.3
18.2
16.9
23.8
23.8
12.9
18.3
20.3
18.2
32.4
32.4
13.2
16.9
17.2
13.8
19.6
25.4
16.9
17.3
21.3
15.7
20.2
23.7
18.7
[Cu (L2)(OAc)]
[Zn
(HL2)2(OAc)2]
HL3
[Cu (L3) (OAc)]
[Zn (HL3)
NA
NA
13.1
NA
NA
NA
11.2
17.6
13.4
12.6
24.3
15.3
18.3
18.9
22.6
17.5
33.7
19.8
(OAc)2].2H2O
HL4
[Cu(L4)
NA
NA
NA
NA
13.3
16.5
15.7
22.3
17.6
12.3
19.5
29.8
(OAc)].3H2O
[Zn (HL4)
8.5
NA
12.3
12.7
15.4
17.6
(OAc)2].2H2O
HL5
[Cu (L5)
13.6
11.2
NA
NA
16.7
10.2
19.2
9.8
15.9
15.9
16.8
14.6
(OAc)].2H2O
[Zn (L5) 2]
9.4
NA
14.6
14.3
11.7
13.6
NA = No Activity.
against Aspergillus fumigatus and it even displayed higher
activity than Amphotericin B,(iii) analogously, [Cu(L2)
(OAc)] possessed more potent activity than its parent
ligand and it displayed similar activity like the fungicide
in use, (iv) metal chelates have higher activity than free
ligands and this may be clarified in terms of chelation
theory and overtone's concept.[47] The complexes
increased the lipophilicity and thus, enhanced the
penetration into lipid membranes and blocked the sites
on the enzymes of the microorganism, (v) the activity of
the complexes versus different organisms relies on either
the differences in ribosome in microbial cells or the
impermeability of the microbe's cells.[46]
activity[48] and the MIC (μg / mL) results are given in
Table 6. The [Cu(L2)(OAc)] complex exhibited high activ-
ity against B. subtilis (MIC = 0.4 μg / mL), E. Coli and
S. Pneumonia (MIC = 1.95 μg/mL) and P. Aeruginosa
(MIC = 7.81 μg/mL).
3.3 | In vitro cytotoxicity assessment
Searching for novel metal complexes like cis-
diaminodichloro platinum (II) (cisplatin) for cancer treat-
ment has witnessed a growing research interest and a
great number of even non-platinum complexes exhibit
remarkable activity in this concern.[22,49,50] The anti-
tumor studies of HL1, [Cu(L2)(OAc)] and [Cu(L3)(OAc)]
were estimated versus liver cancer (HEPG2), breast
The free HL1, as well as the complexes [Cu(L2)(OAc)]
and [Cu(L3)(OAc)], were selected to determine the mini-
mum inhibitory concentration (MIC) for antibacterial

EL-DISSOUKY ET AL.
21 of 23
TABLE 6 Minimum inhibitory concentrations (MIC) in (μg/mL) for antibacterial activity
E. Coli ATCC
6538
P.Aeruginosa ATCC
9027
S.Pneumonia ATCC
49619
B.subtilis ATCC
6633
Compound
(Gram negative)
(Gram positive)
Streptomycin (Gram
0.03
3.9
negative)
Penicillin G (Gram positive)
HL1
[Cu (L2)(OAc)]
[Cu (L3)(OAc)]
0.06
62.5
1.95
7.81
0.03
31.25
0.49
3.9
31.25
1.95
7.81
62.5
7.81
15.63
TABLE 7 IC50 values (μg/ml) in Doxorubicin as standard for HL1, [Cu (L2 − 3) (OAc)] against HEPG2, MCF7 and HCT 116 (doses
ranging from 0 to 50 μg/ml)
Compound
Doxorubicin
HL1
[Cu (L2)(OAc)]
[Cu (L3) (OAc)]
MCF-7 (Breast carcinoma)
HCT-116 (Colon carcinoma)
HEPG-2 (Hepatocellular)
0.44
15.5
6.2
0.47
9.6
1.2
16.2
9.1
7.4
6.9
12.5
4.8
FIGURE 8 Plot of cell viability % versus concentration of HL1 ligand, [Cu(L2)(OAc)] and [Cu (L3)(OAc)] against: a) HCT-116, b)
HEPG-2, c) MCF-
cancer (MCF7) and colon cancer (HCT 116) as well as
the IC50 values using doxorubicin as a standard are listed
in Table 7 and shown in Figure 8. The [Cu (L3)(OAc)]
exhibited higher activity versus HEPG-2 than other cell
lines; IC50 = 4.8 μg/ml. Noteworthy, the [Cu(L2)(OAc)]
exhibited potent activity against breast carcinoma MCF-7
and colon carcinoma; IC50 = 6.2, 7.4 and 9.1 μg/ml,
respectively. These results might be recommended as
new findings of promising antitumor candidates for clini-
cal and experimental chemotherapy.
4 | CONCLUSIONS
The targeted well-separated spherical nanosized ligands
HL1-HL5 were prepared. The heating ethanolic solution
of copper or zinc acetates with an equimolar ratio of the
appropriate ligands furnished the corresponding com-
plex. 1H-NMR spectrum of HL1, as a representative
example, indicated the presence of four isomers in
(8:5:2:1) ratios attributed to enol-imine-keto-amine tau-
tomerism in DMSO, the enol tautomer was observed as a

22 of 23
EL-DISSOUKY ET AL.
[2] a) M. K. Gupta, H. L. Singh, S. Varshney, A. K. Varshney,
Bioinorg. Chem. Appl. 2003, 1, 34. b) S. K. Adavi, A. A. Yadav,
R. S. Bendre, J. Mol. Str. 2018, 1152, 223.
[3] C. S. Allardyce, P. J. Dyson, Dalton Trans. 2016, 4, 3201.
https://doi.org/10.1039/C5DT03919C
[4] D. P. Pate, S. P. Prajapati, A. K. Rana, P. S. Patel, Pelagia
Research Library 2012, 3, 491.
[5] J. Osredkar, N. Sustar, J. Clinic.Toxicol. 2011, S: 3.
[6] T. J. McCarthy, J. J. Zeelie, D. J. Krause, Clin. Pharma. Ther.
1992, 17, 5.
[7] L. Leinartaite, K. Saraboji, A. Nordlund, D. T. Logan,
M. Oliveberg, J. Am. Chem. Soc. 2010, 132, 13495. https://doi.
org/10.1021/ja1057136
[8] N. Fabris, E. Mocchegiani, Aging 1995, 7, 77. https://doi.org/
10.1007/BF03324297
[9] M. Araya, F. Pizarro, M. Olivares, M. Arredondo,
M. González, M. Méndez, Biol. Res. 2006, 39, 183. https://doi.
org/10.4067/s0716-97602006000100020
resonance hybrid of two canonical structures, the zwitter-
ionic and/or quinoid forms, while the keto-amine tauto-
mer is regarded as trans or cis relative to the C=N bond.
The absence of phenolic-OH signal in [Zn(L1)2].2H2O
and [Zn(L5)2] confirmed its deprotonation upon complex-
ation. Other zinc complexes exhibited phenolic-OH, dis-
appeared upon D2O treatment, unambiguously proved to
bond to zinc (II) ion.
The optimized geometries of HL1-HL5 ligands were
verified by performing time-dependent density functional
analysis (TD-DFT). Quantum chemical parameters
including energy gap, absolute electronegativities, chemi-
cal potentials, absolute hardness, absolute softness, global
electrophilicity, global softness, an additional electronic
charge of the ligands HL1- HL5 were calculated.
The antimicrobial screening results against various
pathogenic bacteria revealed a unique potent activity of
HL1 against Gram-negative bacteria and exhibited effi-
cient potential higher than the standard Gentamicin. The
[Cu(L1)(OAc)] and [Cu(L3)(OAc)] complexes displayed
better activity compared to standard bacteriosides in use.
It was noticed that [Cu(L2)(OAc)], [Cu(L3)(OAc)],
[Zn (HL3)(OAc)2] and [Zn (HL4)OAc)2] exerted higher
activity compared to their ligands. The minimum inhibi-
tory concentration (MIC) of [Cu(L2)(OAc)] exhibited
high activity against B. subtilis (0.4 μg/mL), E. Coli and
S. Pneumonia (1.95 μg/mL) and P. Aeruginosa
(7.81 μg/mL). in vitro antitumor studies, [Cu(L3)(OAc)]
[10] Y. Christen, Am. J. Clin. Nutr. 2000, 71, 621S. https://doi.org/
10.1093/ajcn/71.2.621s
[11] B. K. Bitanihirwe, M. G. Cunningham, Synapse 2009, 63, 1029.
https://doi.org/10.1002/syn.20683
[12] a) S. J. Lippard, J. M. Berg, Principles of bioinorganic chemistry,
University Science Books, Mill Valley, California 1994. ISBN
0-935702-73-3 b) E. D. Harris, Nutr. Rev. 2001, 59, 281. https://
doi.org/10.1111/j.1753-4887.2001.tb07017.x
[13] C. Pichot, reactive nanocolloids for nanotechnologies and mic-
rosystems, in colloidal nanoparticles in biotechnology, (Ed:
A. Elaissari), wiley-interscience a john wiley & sons, inc., pub-
lication 2008 1.
[14] M. Gaber, H. A. El-Ghamry, S. K. Fathalla, M. A. Mansour,
Mater. Sci. & Eng. C. 2018, 83, 78.
exhibited
remarkable
activity
against
HEPG-2
[15] T. L. Riss, R. A. Moravec, Assay Drug Dev. Technol. 2004, 2, 51.
https://doi.org/10.1089/154065804322966315
[16] A. D. Becke, J. Chem. Phys. 1993, 98, 5648. https://doi.org/10.
1063/1.464913
[17] P. C. Hariharan, J. A. Pople, Theoret. Chim. Acta 1973, 28, 213.
https://doi.org/10.1007/BF00533485
[18] M. J. Frisch, et al, Gaussian 03. Revision B.01. Gaussian. Inc.
Pittsburgh PA, 2003.
(IC50 = 4.8 μg/ml). The [Cu(L2)(OAc)] showed potent
activity against MCF-7 and HCT 116 (IC50 = 7.4 and
9.1 μg/ml). These results might be recommended as new
findings of promising antitumor candidates for clinical
and experimental chemotherapy.
CONFLICT OF INTEREST
The authors declare that no conflict of interest.
[19] T. L. Decker, M. L. Lohmann-Matthes, J. Immunol. Method
1988, 115, 61. https://doi.org/10.1016/0022-1759(88)90310-9
[20] H. H. A. M. Hassan, E. M. E. Mansour, A. M. S. A. Zeid,
E. R. El-Helow, A. F. Elhusseiny, R. Soliman, Che. Cent. J
2015, 9, 44. https://doi.org/10.1186/s13065-015-0123-2
[21] G. M. G. Hossain, A. J. Amoroso, A. Banu, K. M. A. Malik, Poly-
hedron 2007, 26, 967. https://doi.org/10.1016/j.poly.2006.09.056
[22] A. F. El Husseiny, A. El-Dissouky, A. M. H. Al-Hamza,
H. A. M. Hassan, J. Coord. Chem. 2015, 68, 241. https://doi.
org/10.1080/00958972.2014.982551
AUTHOR CONTRIBUTIONS
Ali El-Dissouky: Methodology; project administration;
supervision. Eslam S. Abu-Elsoud: Formal analysis;
investigation. Afaf Abdel Razik: Formal analysis; inves-
tigation. Mohamed K. Awad: Data curation; software;
validation. Hammed H.A.M. Hassan: Formal analysis.
[23] R. Dennington, T. Keith, J. Millam, Gauss View, Version 4.1.2,
Semichem Inc., Shawnee Mission, KS. Google Scholar, 2007.
[24] W. H. Mahmoud, R. G. Deghadi, M. M. I. El Desssouky,
G. G. Mohamed, Appl. Organometal Chem. 2019, 33, e4556.
https://doi.org/10.1002/aoc.4556
ORCID
Amel F. Elhusseiny https://orcid.org/0000-0001-6395-
5742
[25] R. A. Bhat, D. Kumar, A. Alam, B. A. Mir, A. Srivastava,
M. A. Malla, M. A. Mir, J. Mol. Str. 2018, 1173, 72. https://doi.
org/10.1016/j.molstruc.2018.06.061
[26] G. G. Mohamed, M. A. Zayed, S. M. Abdallah, J. Mol. Str.
2010, 979, 62. https://doi.org/10.1016/j.molstruc.2010.06.002
REFERENCES
[1] H. M. Dalloul, K. N. El–Nwairy, A. Z. Shorafa,
A. S. A. Samaha, MOJ Biorg. Org. Chem. 2017, 1, 255. https://
doi.org/10.1155/S1565363303000244

EL-DISSOUKY ET AL.
23 of 23
[27] M. A. Arafath, F. Adam, M. R. Razali, L. E. A. Hassan,
M. B. K. Ahamed, A. M. Majid, J. Mol. Str. 2017, 1130, 791.
[28] A. F. Elhusseiny, E. S. Aazam, H. M. Al-Amri, Spectrochim.
Acta Part A 2014, 128, 852. https://doi.org/10.1016/j.saa.2014.
03.003
[29] M. A. EL-Nawawy, R. S. Farag, I. A. Sabbah, A. M. Abu–Yamin,
IJPSR 2011, 2, 3143. https://doi.org/10.13040/IJPSR.0975-8232
[30] A. B. P. Lever, Coord. Chem. Reviews 1968, 3, 119. https://doi.
org/10.1016/S0010-8545(00)80107-1
[42] M. L. Dhar, O. Singh, J. Therm. Anal. 1991, 37, 259. https://
doi.org/10.1007/BF02055928
[43] H. Nikaido, T. Nakae, Adv. Microbiol. And Phys. 1979, 20, 163.
https://doi.org/10.1016/S0065-2911(08)60208-8
[44] M. Abdul Qadir, M. Ahmed, H. Aslam, S. Waseem,
M. I. Shafiq, J. Chem. 2015, 2015, 1. https://doi.org/10.1155/
2015/524056
[45] F. Barbato, V. Cirocco, L. Grumetto, M. I. La Rotonda, Eur.
J. Pharm. Sci. 2007, 31, 288. https://doi.org/10.1016/j.ejps.2007.
04.003
[31] a) R. Karbouje, A El-Dissouky, E Al-Saleh, B Jeragh, J. Coord.
Chem.
2010,
63,
868.
https://doi.org/10.1080/
[46] A. F. Elhusseiny, A. El-Dissouky, A. M. Al-Hamza, H. H.
A. M. Hassan, J. Mol. Str. 2015, 1100, 530. https://doi.org/10.
1016/j.molstruc.2015.07.049
[47] B. G. Tweedy, Phytopathology 1964, 55, 910.
[48] S. Jayakumar, D. Mahendiran, D. Arumai Selvan, A. Kalilur
Rahiman, J. Mol. Str. 2019, 1196, 567. https://doi.org/10.1016/
j.molstruc.2019.06.088
[49] A. F. Elhusseiny, H. H. A. M. Hassan, Spectrochim. Acta A.
2013, 103, 232. https://doi.org/10.1016/j.saa.2012.10.063
[50] Y. Kwon, J. Song, H. Lee, E. Kim, K. Lee, S. Lee, S. J. Kim,
Med. Chem. 2015, 58, 7749. https://doi.org/10.1021/acs.
jmedchem.5b00764
00958971003645946 b) L. A. Saghatforoush, S. Hosseinpour,
M. W. Bezpalko, W. S. Kassel, Inorg. Chim. Acta 2019, 484,
527. https://doi.org/10.1016/j.ica.2018.04.053
ꢀ
ꢀ
ꢀ
ꢀ
[32] J. Matijevic-Sosa, M. Vinkovic, D. Vikic-Topic, Croat. Chem.
Acta 2006, 79, 489. https://hrcak.srce.hr/5662
[33] E. S. Aazam, A. Fawazy, P. B. Hitchcock, Acta Crystallogr. E
2006, 62, o4285. https://doi.org/10.1107/S1600536806034519
[34] R. J. Santos-Contreras, A. Ramos-Organillo, E. V. Garcίa-Báez,
I. I. Padilla-Martίnez, F. J. Martίnez-Martίnez, Acta
Crystallogr. C. 2009, 65, o8. https://doi.org/10.1107/S0108270
108040407
[35] A. A. Emara, A. A. Saleh, O. M. I. Adly, Spectrochim. Acta Part
A 2007, 68, 592. https://doi.org/10.1016/j.saa.2006.12.034
[36] A. F. Elhusseiny, H. H. A. M. Hassan, H. Hussien, A. El-
Dissouky, R. A. Palmer, J. K. Cockcroft, Transition Met. Chem.
2015, 40, 643. https://doi.org/10.1007/s11243-015-9958-6
[37] B. K. Singh, U. K. Jetley, R. K. Sharma, B. S. Garg, Spe-
ctrochim. Acta A 2007, 68, 63. https://doi.org/10.1016/j.saa.
2006.11.001
SUPPORTING INFORMATION
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in the Supporting Information section at the end of this
article.
How to cite this article: El-Dissouky A, Abu-
Elsoud ES, Abdel Razik A, Awad MK,
Hassan HHAM, Elhusseiny AF. Synthesis,
molecular modeling, TD-DFT, antimicrobial, and
in vitro therapeutic activity of new spherical nano-
sized sulfonamide imine ligands and their zinc (II)
and copper (II) complexes. Appl Organomet Chem.
2020;e5953. https://doi.org/10.1002/aoc.5953
[38] a) M. S. Masoud, E. A. Khalil, A. M. Hafez, A. F. El-Husseiny,
Spectrochim. Acta A 2005, 61, 989. https://doi.org/10.1039/
B417739H b) A. C. Warden, L. Spiccia, M. T. W. Hearn,
J. F. Boas, J. R. Pilbrow, Dalton 2005, 10, 1804.
[39] A. F. Elhusseiny, H. Hussien, H. H. A. M. Hassan, Lett. Org.
Chem. 2019, 16, 235.
[40] H. H. Horowitz, G. A. Metzger, Anal. Chem. 1963, 35, 1464.
https://doi.org/10.1021/ac60203a013
[41] E. Kissinger, Anal. Chem. 1957, 29, 1702. https://doi.org/10.
1021/ac60131a045