Synthesis of New Dicoumarol Based Zinc Compounds and their Invitro Antimicrobial Studies

Abstract

The dicoumarol derivatives were reacted with Zn (II) salt yielding the complexes (1-10) where metal centre was seen to be coordinated with dicoumarols through hydroxyl and carbonyl sites of attachments. All the synthesized compounds were studied spectroscopically using1H,13C{1H}-NMR, infrared spectroscopic method, and analytically using ES(+,-)-MS, elemental analyses and conductance studies. The combined NMR and mass spectral data suggested the attachment of two ligands to the zinc (II) centre. Hydroxyl site is deprotonated and take part in charge neutralization of metal center. The synthesized zinc based dicoumarol compounds were screened for antimicrobial activities against Gram negative bacteria Escherichia coli, Salmonella typhus, Agrobacterium tumefaciens, Erwinia carotovora, Pseudomonas aeruginosa, Klebsiella pneumoniae, Gram positive bacteria Staphylococcus aureus, Bacillus subtilis, Bacillus atrophaeus and fungal Strain Candida albicans. All the compounds shown exceptional antimicrobial and antifungal activities.

Full text

Article J. Mex. Chem. Soc. 2015, 59(2), 137-142
© 2015, Sociedad Química de México
ISSN 1870-249X
Synthesis of New Dicoumarol Based Zinc Compounds and their Invitro
Antimicrobial Studies
Sadia Rehman*1,a, Muhammad Ikram*,a and Fazle Subhan1
1 Department of Chemistry, Abdul Wali Khan University Mardan, Pakistan. E-mail: sadia@awkum.edu.pk
* ikram@awkum.edu.pk
a Equal Contributors
Received January 9th, 2015; Accepted March 18th, 2015
Abstract. The dicoumarol derivatives were reacted with Zn (II)
salt yielding the complexes (1-10) where metal centre was seen to
be coordinated with dicoumarols through hydroxyl and carbonyl
sites of attachments. All the synthesized compounds were studied
spectroscopically using 1H, 13C{1H}-NMR, infrared spectroscopic
method, and analytically using ES(+,-)-MS, elemental analyses and
conductance studies. The combined NMR and mass spectral data
suggested the attachment of two ligands to the zinc (II) centre.
Hydroxyl site is deprotonated and take part in charge neutraliza-
tion of metal center. The synthesized zinc based dicoumarol com-
pounds were screened for antimicrobial activities against Gram
negative bacteria Escherichia coli, Salmonella typhus, Agrobacterium
tumefaciens, Erwinia carotovora, Pseudomonas aeruginosa, Klebsiella
pneumoniae, Gram positive bacteria Staphylococcus aureus, Bacillus
subtilis, Bacillus atrophaeus and fungal Strain Candida albicans. All
the compounds shown exceptional antimicrobial and antifungal
activities.
Key words: Dicoumarols, zinc compounds, spectral analysis, antimi-
crobial, antifungal activities
Resumen: Derivados del dicoumarol se hicieron reaccionar con sales de
Zn (II) para formar los complejos (1-10), en donde el centro metálico se
encuentra coordinado con la moléculas de dicumarol a través de los gru-
pos hidroxilos y carbonilos. Todos los compuestos sintetizados fueron
estudiados espectroscópicamente, utilizando: RMN de 1H, 13C{1H}, es-
pectroscopia de infrarrojo; y analíticamente, utilizando: espectrometría
de masas con ionización por electroespray ES(+,-)-MS, análisis elemental
y conductancia. Los datos de RMN y de espectrometría de masas sugie-
ren que existen dos ligandos unidos al centro de Zn (II). Los grupos hi-
droxilo se encuentran desprotonados y contribuyen a la neutralización de
la carga del metal central. Los compuestos de dicoumarol base Zinc, sin-
tetizados en este trabajo, fueron evaluados en su actividad antimicrobiana
con bacterias Gram Negativas: Escherichia coli, Salmonella typhus,
Agrobacterium tumefaciens, Erwinia carotovora, Pseudomonas
aeruginosa, Klebsiella pneumoniae; bacterias Gram positivas:
Staphylococcus aureus, Bacillus subtilis, Bacillus atrophaeus y la
cepa fungica de Candida albicans. Todos los compuestos mostraron
actividades excepcionales, tanto antimicrobianas como anti fúngicas.
Palabras clave: Dicoumarol; compuestos de zinc; análisis espectros-
cópico; actividad antimicrobiana; actividad antifúngica
Introduction
Zinc is one of the essential metal ion found in all forms of life
and is involved in many regulatory activities inside body which
includes growth and development of the body, normal brain
functioning and gene expressions. An average adult human be-
ing has around 3 g of zinc in the body. It also play vital role in
preventing many diseases like pneumonia, malaria, common
cold and cancers etc [1,2].
Zinc if combined with coumarin derivatives may function
as good inhibitor of many enzymes, cure diseases by inhibiting
the activities of many pathogenic microbes and recently tested
for the anticancer activities. Through coordination of dicouma-
rols with zinc (II) ion a library of compounds can be synthe-
sized with new type of zinc binding groups (ZBG’s). Though
the ZBG of hydroxamic acid and other heterocyclic ZBG’s
were also synthesized but the present library of ZBG’s provide
insight into the natural product based zinc (II) binders [2-5].
Coumarins can act as effective drugs in treating many dis-
eases like cancer, neuronal diseases, AIDS, etc because they
are regarded as good chelator for the iron in haem or inside
proteins[6]. For example epigallocatechin-3-gallate (EGCG) is
an excellent remedy for neuronal diseases. Structurally it is
comprised of coumarin unit that neutralizes iron (III) safe-
guarding the cell from the oxidative stress of iron (III) [7].
Since the discovery of metal ion role inside body the metal
based chemistry is becoming attractive field for the scientific
community. Metal ions like zinc, copper, iron, and cobalt are
crucial for the proper functioning of cells inside the living
matrix, and any disruption can lead to serious neuropsychiatric
diseases such as Alzheimer’s, Menke’s, Wilson’s and Parkin-
son’s diseases, Friedreich’s ataxia and Hallervorden–Spatz
syndrome [8].
Carbonic anhydrase (CAs) is one of the important en-
zymes involved in the conversion of carbon dioxide to carbon-
ate and proton, a very simple but essential step to overcome the
carbon dioxide concentration inside cells. This process is slow
without the presence of a suitable metallic catalyst [9]. CAs
evolved independently at least five times, with five genetically
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138 J. Mex. Chem. Soc. 2015, 59(2) Sadia Rehman et al.
VLWHWKHȖ&$VDUHSUREDEO\)H,,HQ]\PHVEXWWKH\DUHDOVR
active when bounded to Zn(II) or Co(II) ions), whereas the
ȗFODVVXVHV&G,,RU=Q,,WRSHUIRUPWKHSK\VLRORJLFUHDF-
tion catalysis [13-16].
Metallo thioneins, the ZIP and ZnT families of proteins
distribute the zinc ions for specific activities. Therefore zinc is
very essential metal ion either as mobile or chelatible and
much attention was paid by the scientists all round the world.
The role of zinc can be seen in many zinc enriched tissues of
hippo campus, pancreas, and most important prostate [17]. In-
tra cellular zinc trafficking therefore is attracting much atten-
tion, hence our work aimed to synthesize the coordination
complex of biologically important coumarins and use them for
the in vitro antimicrobial studies [18]. The active dicomarols
reported earlier were used for the synthesis of zinc based deriv-
atives [19].
2. Results and discussion
2.1 Spectral analyses
Dicoumarols derived from the condensation of different al-
dehydes with 4-hydroxycoumarin were reacted with
[Zn{N(SiMe3)2}2] [21] to get the tetrahedral complexes in
1:2 molar metal to ligand ratio. These complexes were char-
acterized unambiguously using different spectroscopic and
analytical techniques. All the ligands were found to be an-
ionic in nature and coordinating to the zinc center through
lactons and hydroxyl site of attachments [19].
The high resolution ES+-MS analyses revealed the specif-
ic molecular ion peaks with reasonable abundance, exceptions
were seen for the 4 and 10 metal complexes. The reason may
be due to the unstable nature of these two complexes in solu-
tion formation. The compositions of all the zinc based metal
complexes (1-10) of dicoumarols were also confirmed by ele-
mental analyses.
Further structural studies was done using techniques like
1H and 13C{1H} NMR along with infrared spectral studies.
Multinuclear NMR and infrared studies confirm the formula-
tion revealed from elemental analyses and MS spectral studies.
The resonances caused by the N(SiMe3)2 were replaced by di-
coumarols. The deprotonation of strong hydrogen bonded phe-
nols is therefore very easily attained. In previous studies such
deprotonation was obtained with sodium metals or sodium me-
thoxide which is also confirmed by us in our sodium work in
the field of the same ligands [20]. The unambiguous and suc-
cessful deprotonation along with successful approach to break
the strong intramolecular hydrogen bonds is therefore one of
beneficial aspects of the [Zn{N(SiMe3)2}2]. The CH proton
found at the linking site of the two coumarin groups was found
to be resonating at 5.3-5.9 ppm depending upon the variation
in the aromatic aldehydes [19]. All the complexes show mul-
tiplates in the region of 6-9 ppm, assigned to the resonances
caused by aromatic protons. The hydroxyl resonance, ob-
served at 11-17 ppm in the free ligands, was found completely
absent in the 1H-NMR spectra of all the zinc complexes. The
13C{1H}-NMR also support the 1H-NMR spectral analyses,
the hydroxyl based carbon and lactone carbonyl resonances
ZHUHIRXQGORZILHOGFRPSDUHGWRWKHQHDWOLJDQG¨į a
ppm). Therefore all the observations were found completely in
line with the complexation behavior for the dicoumarol ligands
coordinating through these two sites of attachments. In an im-
pure NMR spectra of the samples show a singlet at 0 ppm
which was assigned to the HN(SiMe3)2. On purification such
resonances were completely removed. The infrared spectra
also established the attachment of dicoumarol ligands through
lactone and phenolic sites. The vibration caused by hydroxyl
group was completely diminished by the complexation to zinc
centre whereas in other cases it is broadened to a very large
extent compared to the neat ligand. The lactonic stretch was
IRXQGPLVSODFHGE\¨ȣ FP-1, suggesting its participa-
tion in coordination. The general structure of the produced
complexes is shown in Fig. 1.
2.2 Antimicrobial activities
All the synthesized zinc complexes were subjected to their an-
timicrobial activities against selected pathogenic Gram posi-
tive bacteria, Gram negative bacteria and a fungal strain. The
activities of all the synthesized compounds were compared
with a standard drug already used for stopping the pathogenic
activities of tested microorganisms. As may be depicted from
table 1, all the compounds were found much more active
against the Bacillus atrophaeus except 6. By comparing these
results with the bare dicoumarol ligands (as given in table 2)
[19] it can be concluded that metal complexation make the li-
gands much more active. The reason for the enhanced activi-
ties may be due to the increase in hydrophobicity in complexes.
The results for the antimicrobial activities of these compounds
against Bacillus subtilis and Bacillus atrophaeus are very
close. Therefore we can conclude that all the zinc based metal
complexes of dicoumarols are showing potential antimicrobial
activities against Bacillus species of Gram positive bacteria.
On the other hand all the zinc based metal complexes of dicou-
marol were found moderately active against Gram negative
ZKHUH5 DOGHK\GHVZLWKGLIIHUHQWVXEVWLWXWLRQV
Fig. 1. Proposed structure of Zinc (II) complexes of dicoumarols

Synthesis of New Dicoumarol Based Zinc Compounds and their Invitro Antimicrobial Studies 139
bacteria viz Klebsiella pneumoniae, Salmonella typhus, Pseu-
domonas aeruginosa, and Escherichia coli and Gram positive
bacteria like Staphylococcus aureus. Strong antimicrobial ac-
tivities were observed against Agrobacterium tumefaciens,
Erwinia carotovora, and Candida albican. All the compounds
were found much more active than the bare ligands. These
results show that zinc which is also essential metal for many
body functions can also be used as potential antimicrobial ther-
apeutic agent for decreasing or completely vanishing the func-
tions of the microbes in the form of metal complex of
dicoumarol ligand.
Compound 1 was found more active than the parent di-
coumarol ligand against all the tested microbes except Candi-
da albican and Erwinia carotovora, compound 2 was more
active than the dicoumarol ligand except the Pseudomonas
aeruginosa, similar activities were seen for all the compounds
from 3-10. Compounds like 3, 5, 7, 8, & 9 were found much
active against Bacillus atrophaeus than the standard drug
erythromycin. Compounds 2 & 10 showed similar activities
against Bacillus atrophaeus which are aslo comparable to the
drug. Compound 2 was found much active than the standard
drug in inhibiting the activities of Bacillus subtilis. None of the
metal based compound was found active against the Klebsiella
pneumoniae, Salmonella typhus, Pseudomonas aeruginosa,
Escherichia coli, Erwinia carotovora, and Staphylococcus au-
reus. Except compound 1, 4 and 6 all the tested compounds
showed greater activities against the Candida albican as com-
pared to the standard drug. Similarly all the tested compounds
reveal greater activities against Agrobacterium tumefaciens
except the compound 6.
Table 1. In Vitro antimicrobial activities of zinc complexes dicoumarols against different animal and plant pathogens
Compounds Bacillus
atrophaeus
(mm)
Bacillus
subtilis
(mm)
Klebsiella
pneumoniae
(mm)
Salmonella
typhus
(mm)
Pseudomonas
aeruginosa
(mm)
Escherichia
coli
(mm)
Staphylococcus
aureus
(mm)
Candida
albican
(mm)
Agrobacterium
tumefaciens
(mm)
Erwinia
carotovora
(mm)
1 24 24 16 16 --- 15 16 --- 22 ---
2 25 28 19 12 --- 24 15 22 26 15
3272212132114 222324 16
4 22 22 16 --- 16 16 17 --- 22 15
5262209132225 192422 14
6 19 15 11 --- 20 24 21 19 13 15
7 29 20 --- 12 20 22 19 21 26 15
8 29 22 --- --- 21 25 21 25 24 18
9272514202019 212327 22
10 25 20 20 10 20 20 21 24 26 16
Standard 25 26 29 42 36 38 34 16 15 26
Gram positive bacteria: Bacillus atrophaeus, Bacillus subtilis, Staphylococcus aureus, standard used was erythromycin in 6 μM
Gram negative bacteria: Klebsiella pneumoniae, Salmonella typhus, Pseudomonas aeruginosa, Escherichia coli, Agrobacterium tumefaciens,
Erwinia carotovora, standard used was ciprofloxacin in 6 μM
Fungal Strain: Candida albican, standard used was clothrimazol in 6 μM
Table 2. In Vitro antimicrobial activities of dicoumarols against different animal and plant pathogens*
Compounds Bacillus
atrophaeus
(mm)
Bacillus
subtilis
(mm)
Klebsiella
pneumoniae
(mm)
Salmonella
typhus
(mm)
Pseudomonas
aeruginosa
(mm)
Escherichia
coli
(mm)
Staphylococcus
aureus
(mm)
Candida
albican
(mm)
Agrobacterium
tumefaciens
(mm)
Erwinia
carotovora
(mm)
L125 22 --- --- 20 14 16 22 22 15
L212 09 09 06 09 --- 16 12 10 10
L326 22 --- --- 16 --- 09 15 20 ---
L417 17 --- --- 18 12 __ 12 16 11
L515 12 --- 11 15 10 13 30 20 ---
L613 15 --- --- 18 --- 13 19 27 13
L721 22 --- 12 18 12 11 20 24 17
L816 20 11 --- 20 09 15 20 20 ---
L921 21 12 10 19 19 09 21 20 15
L10 22 25 --- --- 15 12 12 --- 28 11
Standard 25 26 29 42 36 38 34 16 15 26
[19] Rehman, S.; Ikram, M.; Baker, R. J.; Zubair, M.; Azad, E.; Min, S.; Riaz, K.; Mok, K. H.; Rehman, S.-U-.; Chem. Cent. J., 2013, 7, 68.

140 J. Mex. Chem. Soc. 2015, 59(2) Sadia Rehman et al.
By comparison of the activities of dicoumarols and their
zinc based metal complexes it becomes clear that the zinc com-
plexation make the ligands much active against the pathogenic
microbes.
3. Conclusion
Zinc metal complexes of the dicoumarols were synthesized in-
situ by reacting [Zn{N(SiMe3)2}2] with the ligands in THF as
a medium. All the metal complexes (1-10) were assigned ge-
ometries using various spectro-analytical techniques. In vitro
antimicrobial activities revealed that all the metal complexes
(1-10) except 6 are more active against Gram positive bacteria
and Candida albican, whereas moderate activities were ob-
served against Gram negative bacteria. The most important
aspect of these metal complexes is the presence of nontoxic
and bioregulatory zinc ion, which can make them very useful
as effective pharmaceutical drug.
4. Experimental
4.1 Materials and methods
All chemicals, buffers and solvents used were of analytical
grade. Benzaldehyde, 4-nitrobenzaldehyde, 4-chlorobenzalde-
hyde, and N,N-dimethyl-4-benzaldehyde were obtained from
Fluka whereas 3-pyridinecarboxaldehyde, 3-indolecarboxal-
dehyde, 4-methoxybenzaldehyde, vaniline, 2-hydroxynaph-
thaldehyde, salicyldehyde, dimethylsilazane and butyllithium
were obtained from Sigma Aldrich and were used as such with-
out further purification. Zinc chloride was obtained from fluka,
and solvents were obtained from local suppliers of Sigma Al-
drich, Merck or Fluka and were distilled at least twice before
use. Unless otherwise stated, all reactions were carried out un-
der a dinitrogen atmosphere.
4.2 Instrumentation
Elemental analyses were carried out on Varian Elementar II.
Melting points were recorded on a Gallenkamp apparatus. IR
spectra were recorded using Shimadzu FTIR Spectrophotome-
ter Prestige-21. 1H-NMR were measured with Bruker DPX
400MHz (400.23 MHz) whereas, 13C{1H}NMR were recorded
on Bruker AV 400MHz (150.9 MHz) spectrometers in CD3OD
at room temperature. Chemical shifts are reported in ppm and
standardized by observing signals for residual protons. Molar
conductance of the solutions of the metal complexes was de-
termined with a conductivity meter type HI-8333. All mea-
surements were carried out at room temperature with freshly
prepared solutions. Mass spectra were recorded on a LCT Or-
thogonal Acceleration TOF Electrospray mass spectrometer.
4.3 Antimicrobial activity
About 2.8 g/L nutrient agar and nutrient broth were prepared in
deionized water and kept in autoclave set at 1.5 Pounds pres-
sure for about 15 min. The nutrient agar media were poured
aseptically into sterilized petri dishes in laminar flow under
inert atmosphere. The petri dishes were kept in inverted posi-
tion for about 24 hrs at 37 oC. Bacterial cultures were adjusted
to 0.5 McFarland turbidity standards and Candida albican was
adjusted to 108 cfu/ml. Sterile filter paper of diameter 6mm
was used for bacterial strains whereas its thickness ranged upto
13 mm for fungal strains. These filter papers were in the form
of discs and were seeded with 0.5 McFarland and 106 cfu/ml
cultures of bacteria and fungi respectively. Solutions (0.5 mM)
of the synthesized compounds were applied to the prepared
discs and incubated for 18 hr at 37 oC. Subsequent measure-
ments of the zone of activity were carried out [21].
4.4 Synthesis of dicoumarols
Synthesis of dicoumarols has been described by Sadia et al.
2013 [19]. The sequence of codes L1-L10 used in this manu-
script is following the sequence as described earlier by us [19].
4.5 Synthesis of zinc compounds
Zinc derivatives of the coumarin ligands [19] were prepared by
following the same procedure. [Zn{N(SiMe3)2}2] was synthe-
sized according to the literature procedure [22]. 10 mmol of
butyllithium in n-hexane was added to the 50 mmol dimethyl
silazane dissolved in degassed dry diethyl ether and the reac-
tion mixture stirred for one hour at 0 oC in completely inert
atmosphere. 20 mmol of synthesized yellow liquid Li{N(-
SiMe3)2}2 was added to the 10mmol ethereal solution of zinc
chloride and the mixture stirred under argon for one hour.
White floating powder of [Zn{N(SiMe3)2}2] was obtained af-
ter purifying the sample by washing and recrystallizing from
diethyl ether.
10 mmol of [Zn{N(SiMe3)2}2] was added to 5 cm3 THF
and stirred at 0 oC, 5 mmol of dicoumarol ligand dissolved in
minimum amount of THF was added to this solution and the
mixture stirred for 4-5 hour at room temperature. After the for-
mation of powder, the mixture was filtered and washed many
times with diethyl ether and THF and dried in vacou.
4.5.1 Bis[3,3’-(1H-indole-3-ylmethanediyl-4-hydroxy-2H-
chromen-2-one)]zinc (II) (1)
IR: 3500(bd), 2980(w), 2612(w), 1689(s), 1636(w), 1584(w),
1518(w), 1483(s), 1417(s), 1260(s), 1241(w), 1222(w),
1107(w), 1073(s), 1025(w), 900(w), 848(s), 791(w), 749(w),
695(w), 660(w) cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k):
į V+PHWK\OP+P+GG
JHH +] +  P+GGJHH +]
1H), 7.78 (s, 1H), 7.80 (s, 1H) ppm, 13C{1H}-NMR (150.9
MHz, CD3OD, 303k): į &+ S\UUROH &S\U-
role), 112-138 (CH, aromatic), 155 (C, phenolic), 164 and 165
& 2 ODFWRQH SSP (OHPHQWDO $QDO\VLV &54H36N2O12Zn),
Calc. C: 66.84%, H: 3.74%, N: 2.89%, Zn: 6.74%, Exp. C:
66.44%, H: 3.69%, N: 2.90%, Zn: 6.34%, EI-MS: m/z (%)
968.1554 (100%) [C54H36N2O12Zn +].

Synthesis of New Dicoumarol Based Zinc Compounds and their Invitro Antimicrobial Studies 141
4.5.2 Bis[(3,3’-(4-chlorophenyl)methanediyl-4-hydroxy-2H-
chromen-2-one)]zinc(II) (2)
IR: 3420(bd), 2924(w), 2890(w), 1703(w), 1649(s), 1605(s),
1524(s), 1411(s), 1347(s), 1277(w), 1182(s), 1107(s), 1045(s),
921(s), 894(s), 831(s), 797(s), 758(s), 742(s), 712(s), 699(s),
669(s) cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k): į 
(s, 1H, methyl), 7.18-8.0 (aromatic protons) ppm, 13C{1H}-
NMR (150.9 MHz, CD3OD, 303k): į   &+ PHWK\O
114.8-132 (Aromatic carbons), 152 (C, Chloro), 154 (C, Phe-
nolic), 162 & 164 (C, lactone) ppm. Elemental Analysis
(C50H28Cl2O12Zn), Calc. C: 62.75%, H: 2.95%, Zn: 6.83%,
Exp. C: 62.14%, H: 3.09%, Zn: 6.91%, EI-MS: not observed.
4.5.3 Bis[(3,3’-(4-hydroxyphenyl)methanediyl-4-hydroxy-
2H-chromen-2-one)]zinc(II) (3)
IR: 3700(bd), 2980(bd), 2800(bd), 1704(s), 1649(s), 1605(s),
1526(s), 1469(s), 1414(s), 1245(s), 1182(s), 1107(s), 1042(s),
921(s), 892(s), 831(w), 799(w), 758(s), 743(s), 712(s), 669(s)
cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k): į V+
methyl), 6.63-7.81 (m, aromatic protons) ppm, 13C{1H}-NMR
(150.9 MHz, CD3OD, 303k): į &+PHWK\O
(aromatic carbons), 164 (C, lactone) ppm, Elemental Analysis
(C50H30O14Zn), Calc. C: 65.26%, H: 3.29%, Zn: 7.11%, Exp.
C: 65.80%, H: 5.10%, Zn: 8.89%. EI-MS: m/z (%) 918.0921
(40%) [C50H30O14Zn +].
4.5.4 Bis[(3,3’-(4-nitrophenyl)methanediyl-4-hydroxy-2H-
chromen-2-one)]zinc(II) (4)
IR: 3420(bd), 2924(w), 2890(w), 1703(w), 1649(s), 1605(s),
1524(s), 1411(s), 1347(s), 1277(w), 1182(s), 1107(s), 1045(s),
921(s), 894(s), 831(s), 797(s), 758(s), 742(s), 712(s), 699(s),
669(s) cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k): į 
(s, 1H, methyl), 7.18-8.0 (aromatic protons) ppm, 13C{1H}-
NMR (150.9 MHz, CD3OD, 303k): į   &+ PHWK\O
114.8-132 (Aromatic carbons), 152 (C, nitro), 154 (C, Pheno-
lic), 162 & 164 (C, lactone) ppm. Elemental Analysis (C50H-
28N2O16Zn), Calc. C: 61.39%, H: 2.89%, N: 2.86 %, Zn:
6.69%, Exp. C: 63.01%, H: 2.11%, N: 2.89 %, Zn: 5.93%, EI-
MS: m/z (%) 976.0724 (5%) [C50H28N2O16Zn +].
4.5.5 Bis[3,3’-[(3-methoxy-4-hydroxyphenyl)methanediyl-4-
hydroxy-2H-chromen-2-one)]zinc(II) (5)
IR: 3300(bd), 2980(bd), 1704(s), 1649(s), 1605(s), 1526(s),
1469(s), 1414(s), 1245(s), 1182(s), 1107(s), 1042(s), 921(s),
892(s), 831(w), 799(w), 758(s), 743(s), 712(s), 669(s) cm-1,
1H-NMR (400.23 MHz, CD3OD, 303k): į EUV +
methyl), 6.55-6.64 (m, 1H), 7.19 – 7.31 (m, 2H), 7.50 (t, 3JHH
+]+G3JHH +]+SSP (OHPHQWDO
Analysis (C52H34O16Zn), Calc. C: 63.72%, H: 3.50%, Zn:
6.67%, Exp. C: 62.23%, H: 4.10%, Zn: 6.89%. EI-MS: m/z
(%) 978.1132 (23 %) [C52H34O16Zn +].
4.5.6 Bis[3,3’-(pyridin-3-ylmethanediyl-4-hydroxy-2H-
chromen-2-one)]zinc(II) (6)
IR: 3700(bd), 2980(bd), 2800(bd), 1704(s), 1649(s), 1605(s),
1526(s), 1469(s), 1414(s), 1245(s), 1182(s), 1107(s), 1042(s),
921(s), 892(s), 831(w), 799(w), 758(s), 743(s), 712(s), 669(s)
cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k): į V+
methyl), 6.63-7.81 (m, aromatic protons) ppm, 13C{1H}-NMR
(150.9 MHz, CD3OD, 303k): į &+PHWK\O
(aromatic carbons), 164 (C, lactone) ppm, Elemental Analysis
(C48H28N2O12Zn), Calc. C: 62.40%, H: 3.17%, N: 3.15%, Zn:
7.35%, Exp. C: 62.43%, H: 3.79%, N: 3.98%, Zn: 7.06%, EI-
MS: m/z (%) 888.0928 (100%) [C48H28N2O12Zn +].
4.5.7 Bis[3,3’-[(4-methoxyphenyl)methanediyl-4-hydroxy-
2H-chromen-2-one)]zinc(II) (7)
IR: 2980(w), 1622(s), 1597(s), 1577(s), 1556(s), 1521(s),
1481(s), 1452(s), 1402(s), 1340(s), 1271(s), 1242(s), 1209(s),
1153(w), 1105(s), 1072(s), 1024(s), 979(s), 947(s), 881(s),
815(s), 765(s), 750(s), 717(s), 688(s), 677(s), 610(w), 526(s)
cm-1, 13C{1H}-NMR (150.9 MHz, CD3OD, 303k): į 
(CH, N-CH3), 103.73 (CH, methyl), 114.85-146.99 (aromatic
region), 152.34 (C, phenolic), 164.82 & 167.82 (C, lactone)
ppm, Elemental Analysis (C52H34O14Zn), Calc. C: 65.87%, H:
3.61%, Zn: 6.90%, Exp. C: 66.32%, H: 3.83%, Zn: 7.03%, EI-
MS: m/z (%)946.1234 (7%) [C52H34O14Zn +].
4.5.8 Bis[3,3’-(phenylmethanediyl-4-hydroxy-2H-chromen-
2-one)]zinc(II) (8)
IR, : 3400(bd), 3026(w), 2980(w), 1598(s), 1516(s), 1446(s),
1405(s), 1366(s), 1356(w), 1277(w), 1250(w), 1211(w),
1107(s), 1084(s), 1058(w), 937(w), 837(s), 757(s), 727(s),
693(s) cm-1, 1H-NMR (400.23 MHz, CD3OD, 303k): į 
8.11 (aromatic protons) ppm, 13C{1H}-NMR (150.9 MHz,
CD3OD, 303k): į  &+ PHWK\O DUR-
PDWLF& 2ODFWRQHSSP(OHPHQWDO$QDO\VLV
(C50H30O12Zn), Calc. C: 67.61%, H: 3.40 %, Zn: 7.36%, Exp.
C: 67.21%, H: 3.76 %, Zn: 7.99 %, EI-MS: m/z (%) 886.1023
(60%) [C50H30O12Zn +].
4.5.9 Bis[(3,3’- (4-N,N-dimethylaminophenyl)methanediyl-
4-hydroxy-2H-chromen-2-one)]zinc(II) (9)
IR: 3414(bd), 3242(w), 2980(w), 1622(s), 1597(s), 1577(s),
1556(s), 1521(s), 1481(s), 1452(s), 1402(s), 1340(s), 1271(s),
1242(s), 1209(s), 1153(w), 1105(s), 1072(s), 1024(s), 979(s),
947(s), 881(s), 815(s), 765 (s), 750 (s), 717 (s), 688 (s), 677 (s),
610 (w), 526 (s) cm-1, 13C{1H}-NMR (150.9 MHz, CD3OD,
303k): į &+1&+3), 103.73 (CH, methyl), 114.85-
146.99 (aromatic region), 152.34 (C, C-N-(CH3)2), 164.82 &
167.82 (C, lactone) ppm, Elemental Analysis (C54H40N2O12Zn),
Calc. C: 66.57%, H: 4.14%, N: 2.88%, Zn: 6.71, Exp. C:
66.57%, H: 4.14%, N: 2.88%, Zn: 6.71, EI-MS: m/z
(%)972.1867 (100%) [C54H40N2O12Zn +].
4.5.10 Bis[(3,3’- (2-hydroxy-1,2-dihydronaphthalen-1-yl-4-
hydroxy-2H-chromen-2-one)]zinc(II) (10)
IR: 2980(w), 1622(s), 1597(s), 1577(s), 1556(s), 1521(s), 1481(s),
1452(s), 1402(s), 1340(s), 1271(s), 1242(s), 1209(s), 1153(w),
1105(s), 1072(s), 1024(s), 979(s), 947(s), 881(s), 815(s), 765(s),
750(s), 717(s), 688(s), 677(s), 610(w), 526(s)cm-1, 13C{1H}-
NMR (150.9 MHz, CD3OD, 303k): 103.73 (CH, methyl),
114.85-146.99 (aromatic region), 152.34 (CH, phenolic), 164.82
& 167.82 (C, lactone) ppm, Elemental Analysis (C58H34O14Zn),

142 J. Mex. Chem. Soc. 2015, 59(2) Sadia Rehman et al.
Calc. C: 68.28%, H: 3.36%, Zn: 6.41%, Exp. C: 68.31%, H: 3.87%,
Zn: 6.12%. EI-MS: m/z (%)1018.1234 (10%) [C58H34O14Zn +].
Conflict of interest
The author declares no conflict of interest.
Author’s contribution
Both the authors M. Ikram and S. Rehman equally contributed
to the content of this manuscript and equal first authors.
Acknowledgment
The authors are gratefully acknowledged to the Higher Edu-
cation Commission (HEC) Pakistan for providing financial
assistance.
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