New Zn(II) complexes based on biologically active substituted acetic acid and nitrogen donor ligands: synthesis, crystal structure and biological applications

Article abstract of DOI:10.1080/00958972.2017.1326593

The complexes [Zn(phenylacetato)₂(2-aminopyridin)₂] (3), [Zn(phenylacetato)₂(1,10-phenanthroline)]·H₂O (4), and [Zn(phenylacetato)₂(2,9-dimethyl-1,10-phenanthroline)]·0.5 H₂O (5) were prepa

Full text of DOI:10.1080/00958972.2017.1326593

Journal of Coordination Chemistry
ISSN: 0095-8972 (Print) 1029-0389 (Online) Journal homepage: http://www.tandfonline.com/loi/gcoo20
New Zn(II) complexes based on biologically
active substituted acetic acid and nitrogen
donor ligands: Synthesis, crystal structure and
biological applications
Shayma Kamel, Hijazi Abu Ali & Amani Abu Shamma
To cite this article: Shayma Kamel, Hijazi Abu Ali & Amani Abu Shamma (2017): New Zn(II)
complexes based on biologically active substituted acetic acid and nitrogen donor ligands:
Synthesis, crystal structure and biological applications, Journal of Coordination Chemistry, DOI:
10.1080/00958972.2017.1326593
To link to this article: http://dx.doi.org/10.1080/00958972.2017.1326593
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Date: 13 May 2017, At: 17:13

Publisher: Taylor & Francis
Journal: Journal of Coordination Chemistry
DOI: http://dx.doi.org/10.1080/00958972.2017.1326593
New Zn(II) complexes based on biologically active substituted acetic acid and
nitrogen donor ligands: Synthesis, crystal structure and biological applications
1
1
*
SHAYMA KAMEL , HIJAZI ABU ALI and AMANI ABU SHAMMA
Department of Chemistry, Birzeit University, West Bank, Palestine
The complexes [Zn(phenylacetato) (2-aminopyridin) ] (3), [Zn(phenylacetato) (1,10-
2
2
2
phenanthroline)]·H O (4) and [Zn(phenylacetato) (2,9-dimethyl-1,10-
2
2
1
phenanthroline)]·0.5 H O (5) were prepared and characterized by IR-, UV-Visible, H
2
1
3
and C NMR spectroscopy, and single crystal X-ray diffraction. BNPP hydrolysis of
the complexes and their parent nitrogen ligands showed that the hydrolysis rate of
5
-1 -1
5
-1 -
bis-(4-nitrophenyl) phosphate (BNPP) was 1.7×10 L/mol s for 3, 3.1×10 L/mol s
1
4
-1 -1
for 4 and 4.3×10 L/mol s for 5. Anti-bacterial activities show the effect of
complexation on activity against Gram-positive (S. epidermidis, S. aureus, E.
faecalis, M. luteus and B. Subtilis) and Gram-negative (K. pneumonia, E. coli,
P. Mirabilis and P. Aeruginosa) bacteria using the agar well-diffusion method.
Complex 4 showed good activity against G- bacteria except P. Aeruginosa, and
against G+ bacteria except E. ferabis. Complex 5 showed no activity against G-
bacteria, low activity against M. luteus and B. Subtilis bacteria and high activity
against S. epidemidis and S. aureus. Complex 3 did not show any activity against G-
or G+ bacteria.
*
Corresponding author. Emails: habuali@birzeit.edu; habuali1@yahoo.com
1
These authors contributed equally to this work.
1

Keywords: Zinc(II) complexes; Nitrogen ligands; Zinc(II) phenylacetate; Phosphate
diester hydrolysis; Anti-bacterial activity
1
. Introduction
The metabolism and transport of metal ions and their complexes have been studied
1]. All biological activities of metals are due to their characteristics such as redox
[
activity, many coordination modes, and reactivity towards organic substrates [2].
There are four major categories for the essential chemical elements: (a) bulk elements
-
3
-2
(
H, C, N, O, P, S), (b) macrominerals and ions (Na, K, Mg, Ca, Cl, PO , SO ), (c)
4
4
trace elements (Fe, Zn, Cu), and (d) ultratrace elements that involve nonmetals (F, I,
Se, Si, As, B) and metals (Mn, Mo, Co, Cr, V, Ni, Cd, Sn, Pb, Li); each essential
element has approximate percentages by weight for an adult human [3]. Zinc is
relatively abundant and is essential for many biological processes and must be
included in the diet for optimum health [4].
Carboxylic acids can be ligands and have many biological activities such as
anti-inflammatory effect (ibuprofen, naproxen and tolmetin) [5]. The anti-bacterial
activities of nalidixic acid can be enhanced by complexation with metal ions.
However, in other similar complexes the activities were decreased [6].
Recently, studies on the antimicrobial activity of Nonsteroidal Anti-
Inflammatory Drugs (NSAIDs) showed increased activity when complexed with
transition metals and various nitrogen ligands [7]. Several metal complexes accelerate
the drug action and efficacy of organic therapeutic agents, e.g. Co(II) complexes
bearing mefenamic acid [8], naproxen [9] or tolfenamic acid [10] and Mn(II)
complexes of tolfenamic acid [11] have been studied as anti-inflammatory agents. In
addition, Cu(II) complexes of mefenamic acid, naproxen, diclofenac [12] diflunisal
[
13] and flufenamic acid [14] have been reported. Zinc complexes with biologically
active ligands have pharmaceutical effects because they can catalyze enzymatic
2

processes in biological systems, e.g. zinc(II) aliphatic carboxylates with nitrogen-
based ligands (like valproic acid) [15, 16] and aromatic carboxylates with nitrogen-
based ligands (like naproxen, ibuprofen, Indomethacin…) have been synthesized and
studied as anti-bacterial and anti-malarial agents [17-20].
Phosphate hydrolysis has an important role in many biological and
environmental applications. For example, this hydrolysis represents the cleavage of
the phosphorus bond as shown in scheme 1.
Scheme 1. Phosphate hydrolysis of BNPP.
A hydroxamic acid (HL) containing benzo-15-crown-5 and their copper(II), zinc(II),
cobalt(II) and manganese(II) complexes have been synthesized and studied as
catalysts [21, 22]. The catalytic properties of these complexes and the kinetics and
mechanism of BNPP hydrolysis were investigated. Moreover, the kinetic
mathematical model of BNPP cleavage catalyzed by these complexes has been
proposed [21, 22].
Rapid hydrolysis of the high stable phosphate diester bond in bis-(4-
nitrophenyl) phosphate (BNPP) by enzymes or catalysts containing metal ion
complexes have recently been achieved [21, 22].
2. Experimental
2
.1. Chemicals, materials and biological species
All reagents, chemicals and solvents were purchased from commercial sources and
were used without purification.
3

2
.2. Physical measurements
Solid samples with anhydrous potassium bromide (KBr) were ground and
compressed into a disc to use for IR spectral measurements, which were recorded
-
1
from 200-4000 cm on a TENSOR II (BRUKER) FT-IR Spectrometer. UV-Vis
spectra were recorded on an Agilent 8453 photodiode array (PDA) spectrophotometer
from 200-600 nm using CH OH as solvent. NMR spectra were recorded on a Varian
3
1
13
Unity Spectrometer operating at 300 MHz for H and C nuclei. Melting points were
determined in capillary tubes with an Electrothermal apparatus and Bruker SMART
APEX CCD X-ray diffractometer was used for X-ray data.
2
.3. Synthesis and characterization of zinc(II) compounds
All zinc(II) compounds were prepared at room temperature.
2
.3.1. [bis-(phenylacetato)zinc(II)] (2). Sodium hydroxide (1.0 mmol, 1.5 g) and
phenyl acetic acid (1.0 mmol, 5.0 g) in 100 ml of MeOH were stirred for 3 h. Then
the solvent was evaporated to give a needle solid which was re-dissolved in MeOH
and ZnCl (1.0 mmol, 5.0 g) in 15 ml of MeOH was added to it with stirring. The
2
reaction mixture was stirred for an additional 12 h; the obtained white precipitate was
then filtered, washed with cold water and air dried to give 4.4 g of solid product.
1
[
Zn(C H O ) ] (2). 89% yield; m.p. > 200 °C; H NMR (CDCl ): δ (ppm) 3.39 (s,
8
7
2 2
3
1
3
1
2
H, CH ), 7.21 (s, 5H, CH); C{ H}-NMR (CDCl ): δ (ppm) 43.11 (CH ), 126.21
2
3
2
−1
(
CH), 128.31 (CH), 129.69 (CH), 137.91 (C), 176.98 (C=O); IR (cm , KBr): 3444,
2
350, 1531, 1439, 1391, 723; UV-Vis (MeOH, λ (nm)): 214, 259, 265.
2
.3.2. [Zn(phenylacetato) (2-aminopyridine) ] (3). 2-Aminopyridine (4 mmol, 0.38
2
2
g) dissolved in a minimum of MeOH was added with stirring to a 50 ml MeOH
solution of [bis-(phenylacetato)zinc(II)] (2.0 mmol, 0.40 g), then the clear reaction
4

mixture was stirred for an additional 7 h. The solution was allowed to evaporate to
give solid crystals. Crystals for X-ray structural analysis were obtained by
recrystallization from CH Cl .
2
2
1
[
Zn(C H O ) (C H N ) ] (3). 77% yield; m.p. = 147-149 °C; H NMR (CDCl ): δ
8
7
2 2
5
6
2 2
3
3
(
ppm) 3.64 (s, 2H, CH ), 5.78 (s, 2H, NH ), 6.39 (d, 1H, CH, J = 8.4 Hz), 6.47 (t,
2
2
H-H
3
1
7
1
1
H, CH, J = 12.9 Hz), 7.20 (m, 1H, CH), 7.26 (m, 5H, CH), 7.37 (m, 1H, CH),
.74 (d, 1H, CH, J = 5.4 Hz); C{1H}-NMR (CDCl ): δ (ppm) 43.60 (CH ),
H-H
3
13
H-H
3
2
11.43 (CH), 112.96 (CH), 122.96 (CH), 126.10 (CH), 128.18 (CH), 129.52 (CH),
−1
37.16 (C), 139.73 (CH), 145.97 (CH), 159.05 C(NH ), 178.52 (C=O); IR (cm ,
2
KBr): 3341, 3227, 3024, 2700, 1619, 1567, 1499, 1360, 1271, 1159, 851, 698, 661;
UV-Vis (MeOH, λ (nm)): 296.
2
.3.3. [Zn(phenylacetato) (1,10-phenanthroline)]monohydrate (4). 1,10-
2
Phenanthroline (2.0 mmol, 0.36 g) dissolved in minimum amount of MeOH was
added with stirring to [bis-(phenylacetato)zinc(II)] (2.0 mmol, 0.40 g) dissolved in 50
ml MeOH. The clear solution of the reaction mixture was stirred for an additional 7 h,
then was allowed to evaporate and solid crystals were obtained. Suitable crystals for
X-ray structural analysis were obtained by recrystallization from MeOH.
1
[
Zn(C H O ) (C H N )]·H O (4). 85% yield; m.p. = 101 °C; H NMR (CDCl ): δ
8
7
2 2
13 12
2
2
3
3
(
ppm) 3.63 (s, 2H, CH ), 7.19 (m, 5H, CH), 7.68 (t, 2H, CH, J = 12.6 Hz), 7.76 (s,
2
H-H
3
3
13
1
2
H, CH), 8.32 (d, 2H, CH, J = 8.1 Hz), 9.05 (d, 2H, CH, J = 4.8 Hz); C{ H}-
H-H
H-H
NMR (CDCl ): δ (ppm) 43.43 (CH ), 124.28 (CH), 125.03 (CH), 126.04(CH), 126.58
3
2
(
CH), 128.11(CH), 128.45 (C), 129.39 (CH), 137.06 (C), 138.85 (CH), 150.12 (CH),
−1
1
80.59 (C=O); IR (cm , KBr): 1998, 1515, 1223, 1144, 1100, 853; UV-Vis (MeOH,
λ (nm)): 277, 292, 325.
5

2
.3.4. [Zn(phenylacetato) (2,9-dimethyl-1,10-phen)] hemihydrate(5). 2,9-
2
Dimethyl-1,10-phen (2.0 mmol, 0.45 g) dissolved in a minimum of MeOH was added
with stirring to [bis-(phenylacetato)zinc(II)] (2.0 mmol, 0.40 g) dissolved in 50 ml
MeOH. The clear solution of the reaction mixture was stirred for an additional 7 h,
then was allowed to evaporate and solid crystals were obtained. Suitable crystals for
X-ray structural analysis were obtained by recrystallization from MeOH.
1
[
Zn(C H O ) (C H N )]·0.5H O (5). 79 % yield; m.p. = 159-165 °C; H NMR
8
7
2 2
15 16
2
2
3
(
CDCl ): δ (ppm) 2.99 (s, 3H, CH ), 3.66 (s, 2H, CH ), 7.15 (t, 2H, CH, J = 15.6
3
3
2
H-H
3
3
Hz), 7.21 (d, 2H, CH, J = 6.9 Hz), 7.28 (d, 2H, CH, J = 7.2 Hz), 7.54 (d, 2H,
H-H
H-H
3
3
13
1
CH, J = 8.4 Hz), 7.64 (s, 2H, CH), 8.19 (d, 2H, CH, J = 8.4 Hz); C{ H}-
H-H
H-H
NMR (CDCl ): δ (ppm) 24.78 (CH ), 43.05 (CH ), 125.55 (CH), 125.99 (CH), 126.25
3
3
2
(
C), 126.86 (CH), 128.10 (CH), 129.35 (CH), 137.35 (C), 139.09 (CH), 140.1 9 (C),
−1
1
60.73 (C), 179.04 (C=O); IR (cm , KBr): 3027, 2800, 1500, 1450, 1340, 1221, 861;
UV-Vis (MeOH, λ (nm)): 201, 231 269.
2
.4. X-ray crystallography
Single crystal X-ray analyses of 3, 4 and 5 were carried out by attaching single
crystals to a glass fiber with epoxy glue, and then transferring to the X-ray
diffractometer system (Bruker SMART APEX CCD) which is controlled by using a
Pentium-based PC running the SMART software package [23]. The diffracted
graphite-monochromated (Kα radiation λ = 0.71073 Å) was detected on a phosphor
screen at -44 °C, held at 6.0 cm from the crystal. A detector array of 512×512 pixels
(
a pixel size ≈ 120 µm) was used to collect data [24]. Crystal data and structure
refinements are summarized in tables 1 and 2.
6

2
.5. Kinetic measurements of BNPP hydrolysis
Optimum concentrations and conditions for the BNPP hydrolysis were chosen by
running different UV-visible kinetic experiments and the best absorbance versus time
plots were used to determine the optimum conditions.
The following conditions were used for all hydrolysis reactions: HEPES“4-(2-
hydroxyethyl)-1-piperazineethanesulfonic acid” buffer with concentration of 50 μM
was prepared by dissolving the appropriate amount in a minimum amount of
deionized water, then controlling the pH to 7.91 using HCl or NaOH and the final
volume was adjusted to 100 ml. BNPP (0.036 g) was dissolved in the prepared buffer
to obtain a concentration of 1 mM. The desired complex concentration was prepared
using methanol as a solvent; the two solutions were kept in a water bath at 25 °C for
1
0 minutes, then (1.5 ml) of the two solutions were mixed in a quartz cell at 25 °C,
the rate of release of p-nitrophenol was directly measured using UV-Vis
-
1
-1
spectrophotometer at λ = 400 nm and an extinction coefficient of 13400 Lmol cm .
The concentration effect of BNPP solution on the hydrolysis process was measured
-4
-5
by preparing 10 and 10 M solutions and the rate of hydrolysis was calculated [25].
3
3
. Results and discussion
.1. Synthesis of Zn(II) complexes
The proposed structure of [bis-(phenylacetato)zinc(II)] 2 and 3, 4 and 5 are shown in
schemes 2 and 3, respectively.
Scheme 2. Synthesis and proposed structure of zinc(II) complexes.
7

Nitrogen donor ligands were mixed with 2 in various ratios as shown in the
Experimental section. The proposed structures are supported by their single crystal X-
ray structure determination. The physical properties and yield of the prepared zinc(II)
complexes are listed in table 3.
Scheme 3. Synthesis and proposed structure of the zinc(II) complexes.
3
3
.2. Crystallographic study
.2.1. X-ray crystal structure of 3. As shown in figure 1, Zn(II) is bound to two
monodentate phenyl acetate and two monodentate 2-ampy ligands. The Zn(1)-O(1)
bond of 1.942(2) Å and Zn(1)-O(3) 1.9359(19) Å and Zn(1)-N(1) 2.056(3) Å and
Zn(1)-N(3) 2.048(2) Å bond distances are obtained. Selected bond distances and
angles are listed in table S1 (Supporting Material).
8

Complex 3 adopted slightly distorted tetrahedral geometry around Zn(II),
O(1)-Zn(1)-O(3) = 129.09(10)°, N(1)-Zn(1)-N(3) = 99.19(10)°, N(1)-Zn(1)-O(1) =
1
08.34(10)°, N(3)-Zn(1)-O(3) = 106.05(9)°.
Further stability of the crystal lattice was gained by intramolecular hydrogen
bonding. Table 4 shows the H-bond distances in (Å), where these bonds are between
O(1), O(2), O(3) and O(4) of the phenyl acetate groups and H of the amino groups as
represented by the dashed lines within a single molecule.
3
.2.2. X-ray crystal structure of 4. The atomic scheme and atom connectivity for 4
are shown in figure 2, in which Zn(II) is covalently bonded to one monodentate
phenyl acetate group, one bidentate phenyl acetate and one bidentate 1,10-phen.
Selected interatomic distances and angles are found in table S2.
Complex 4 adopted slightly distorted trigonal bipyramidal geometry around
Zn(II) with O(3)-Zn(1)-O(4) = 58.56(10)°, N(1)-Zn(1)-N(2) = 79.40(8)°, N(1)-Zn(1)-
O(3) = 104.10(8)°, O(1)-Zn(1)-N(2) = 109.19(8)°.
The water (O1w) is positioned between (O2) of the phenyl acetate groups at
2
.879 Å, (O3) at a distance of 3.231 Å and to another (O1w) at a distance of 3.655 Å.
The water molecule is disordered so the hydrogens could not be found.
.2.3. X-ray crystal structure of 5. The atomic scheme and atom connectivity for 5
3
are shown in figure 3, in which Zn(II) is covalently bonded to one monodentate
phenylacetate group, one bidentate phenylacetate and one bidentate 2,9-dmp.
Selected interatomic distances and angles are found in table S3. Complex 5 has
slightly distorted trigonal bipyramidal geometry around Zn(II), O(1)-Zn(1)-O(4) =
1
11.81(19)°, N(1)-Zn(1)-N(2) = 80.8(3)°, O(1)-Zn(1)-N(2) = 110.45(16)°, N(1)-
Zn(1)-O(3) = 100.1(2)°.
9

The water (O1w) is positioned between two carbonyl groups (O2) of the
phenylacetate group from two neighbor complexes at 2.674 Å. The water molecule is
disordered so the hydrogens could not be found.
3
.3. IR spectroscopy
-
1
Infrared spectral data of sodium phenylacetate complexes from 400-4000 cm as KBr
pellets are summarized in table 5.
In metal carboxylate complexes, the major characteristic of the IR spectra is
-
the frequency of the υ asymmetric (υ ) and υ symmetric (υ ) of carbonyl (COO )
as
s
-
stretches and the difference between them ∆υ(COO ). The frequency of these bands
depends upon the coordination mode of carboxylate. Monodentate complexes exhibit
-
∆
υ(COO ) values that are much greater than ionic complexes. Chelating (bidentate)
-
complexes exhibit ∆υ(COO ) values that are significantly less than the ionic (phenyl
-
acetate) values. ∆υ(COO ) values for bridging complexes are greater than those of
chelating complexes, and close to the ionic values [26].
-
-
The stretching vibrations for sodium phenyl acetate ߭ (COO ) and ߭ (COO )
as
s
-
1
-1
-
have been observed at 1562.2 cm and 1387.1 cm , respectively, with Δ߭COO value
-
1
-
-1
-
of 175.1 cm . In 3, ΔυCOO = 199 cm > ΔυCOO (Na phenyl), so monodentate
-
-1
-
coordination is expected. In 4, ΔυCOO = 139.5 cm < ΔυCOO
indicating
(
Na phenyl)
bidentate coordination. However, according to X-ray, the coordination mode was
bidentate for the first carboxylate group and monodentate for the second. Complex 5
-
-1
-
with ΔυCOO = 226 cm >> ΔυCOO
indicates monodentate coordination.
(
Na phenyl)
All previously mentioned coordination modes of 3-5 are in agreement with their
X-ray structure determination.
Generally, the ν(M-O) and ν(M-N) for metal complexes are weak bands at 430-
-
1
4
74 and 524-576 cm , respectively [27]. These bands for 3-5 are shown in table 5.
1
0

1
13
3
.4. H and C Nuclear Magnetic Resonance
1
The relative intensities of H NMR signals are in accord with the proposed structures,
figures 4 and 5. Due to complex formation, change in the chemical shift takes place.
As shown in table S4 slight upfield and downfield shifts were observed due to
complexation with Zn or/and nitrogen donor ligands.
3
.5. Electronic absorption spectroscopy
Zn(II) complexes with completely filled d orbitals have no d-d electronic transitions.
From the results tabulated in tables 6 and 7, no ligand to metal charge transfer
“LMCT” can be observed due to filled d orbitals. The bands are assigned to MLCT
charge transfer and intraligand transitions e.g., π-π* transition; the spectra of the
complexes are similar to those of nitrogen parent ligands with very small shifts
caused by zinc coordination. MLCT bands were observed at 201-296 nm with є
-
1
-1
values around 3000 Lmol cm [28, 29].
3
.6. BNPP Hydrolysis
The abilities of 3-5 for phosphate diester hydrolysis were studied. The initial rate of
hydrolysis was determined by measuring the absorption of 4-nitrophenolate at 400
nm and various plots of absorbance versus time were obtained
The Michaelis-Menten equation was used for calculating the initial rate against
different concentrations of BNPP and the results are summarized in table 8. A
suggested mechanism is shown in scheme 4: (1) H O coordinates with metal complex
2
to produce complex A, (2) the oxygen on the P=O of the substrate (BNPP) is
coordinated to the complex metal ion, forming intermediate B, (3) intramolecular
metal hydroxide attacks the positive P of BNPP molecule to enhance release of the p-
nitrophenol with first-order rate constant (k) for this step which is considered the key
step for the hydrolysis, (4) after that H O coordinates again with the metal ion
2
quickly, forming D, (5) the intermediate D quickly loses p-nitrophenol and
1
1

phosphoric acid where H O is again bonded to the metal(II) rapidly, and thus
2
completes the catalytic cycle [29, 30-32].
Scheme 4. The proposed mechanism of hydrolysis of BNPP.
3
.7. Anti-bacterial activity
The anti-bacterial activities of the synthesized zinc complexes were screened against
different gram-negative bacteria (K. pneumonia, E. coli, P. Mirabilis and P.
Aeruginosa) and gram-positive bacteria (S. epidermidis, S. aureus, E. ferabis, M.
luteus and B. Subtilis) to show the effect of complexation on anti-bacterial activity.
The average IZD inhibition zone diameters of three trials of the complexes were
measured and stated as average ± standard error and summarized in table 9.
ZnCl and Zn-phenyl did not show anti-bacterial activity against the tested
2
micro-organisms. DMSO was used as negative control to resist any tested
microorganisms, whereas gentamicin (G) and erythromycin (E) were used as positive
control for both G- and G+ bacteria. Complex 3 showed no activity against all tested
bacterial species. Complex 4 showed good activity against G- bacteria except P.
1
2

Aeruginosa, and against G+ bacteria except E. ferabis. Complex 5 showed no activity
against G- bacteria, low activity against M. luteus and B. Subtilis bacteria and high
activity against S. epidemidis and S. aureus.
4
. Conclusion
New Zn(II) complexes with phenyl acetic acid in the presence of 2-ampy, 2,9-dmp
1
and 1,10-phen have been synthesized and characterized. IR, UV-Vis, H and
1
3
1
C{ H}-NMR spectroscopic techniques were used to study the new complexes. X-
ray single crystal diffraction measurements were also determined for 3-5 as evidence
for their structures. Different metal geometries and carboxylate coordination modes
have been proved. The structure of 3 is a slightly distorted tetrahedral geometry with
two monodentate phenyl acetate groups and two monodentate 2-ampy ligands.
Complexes 4 and 5 showed similar distorted trigonal bipyramidal geometries with
one monodentate and one bidentate phenyl acetate group and one bidentate 1,10-phen
or 2,9-dmp, respectively. The obtained results from the kinetic experiments showed
that these complexes can be potent BNPP hydrolysis agents with the activitiy
decreasing in the order 4 > 3 > 5.
Complex 3 did not show any activity against G- or G+ bacteria. Complex 4
showed good activity against G- bacteria except P. Aeruginosa and G+ bacteria
except E. faecalis. Complex 5 showed no activity against G- bacteria, low activity
against M. luteus and B. Subtilis and high activity against S. epidermidis and S.
aureus.
Appendix A. Supplementary data
CCDC 1488198, CCDC 1488200 and CCDC 1488196 contain the supplementary
crystallographic data for 3, 4 and 5, respectively. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax:
1
3

(
+44)1223-336-033; or E-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found in the online version.
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1
6

`
Figure 1. View of the molecular structure of 3 showing the atom numbering scheme.
Ellipsoids represent thermal displacement parameters at the 25% probability level and
hydrogens in calculated positions have been omitted for clarity.
1
7

Figure 2. View of the molecular structure of 4 showing the atom numbering scheme.
Ellipsoids represent thermal displacement parameters at the 50% probability level and
hydrogens in calculated positions have been omitted for clarity.
1
8

Figure 3. View of the molecular structure of 5 showing the atom numbering scheme.
Ellipsoids represent thermal displacement parameters at the 25% probability level and
hydrogens in calculated positions have been omitted for clarity.
1
9

N
O
O
NH2
Zn
N
O
NH2
O
3
1
Figure 4. H-NMR spectrum of 3.
2
0

N
N
Zn
O
O
O
O
5
1
Figure 5. H-NMR spectrum of 5.
2
1

Table 1. Structure refinement and crystal data for 3 and 4.
3
4
Empirical formula
Formula weight
Temperature
C H N O Zn
C H N O Zn
2
6
26
4
4
28 22
2
5
523.88
531.85
293(1) K
0.71073 Å
Triclinic
P-1
293(1) K
Wavelength
0.71073 Å
Crystal system
Space group
Monoclinic
P2(1)/c
Unit cell dimensions
a = 10.877(2) Å
7.918(4)°
b = 11.204(2) Å
4.302(4)°
c = 11.461(3) Å
5.807(4)°
= a = 10.589(1) Å
= 90°
8
= b = 11.165(2) Å
7
= 97.681(2)°
=
c = 12.160(3) Å
90°
=
7
3
3
Volume
1302.9(5) Å
2
2438.3(6) Å
Z
4
3
3
Density (calculated)
Absorption coefficient
F(000)
1.335 Mg/m
1.449 Mg/m
-
1
-1
0.980 mm
544
1.049 mm
1096
3
3
Crystal size
0.36 × 0.36 × 0.13 mm
2.39 to 28.01°
0.36 × 0.29 × 0.26 mm
2.20 to 27.00°
Theta range for data
collection
Index ranges
-14<=h<=14, -
-13<=h<=13, -
23<=k<=23,
- 16<=l<=16
26565
1
4<=k<=14,
15<=l<=14
15064
-
Reflections collected
Independent reflections 6067 [R(int) = 0.0258]
Completeness to theta = 96.4 %
5314 [R(int) = 0.0306]
99.8 %
2
8.03°
Absorption correction
Multi-scan
Semi-empirical from
equivalents
Max. and min.
transmission
0.8832 and 0.7193
6067 / 4 / 332
0.7720 and 0.7038
Data / restraints /
parameters
5314 / 0 / 325
2
2

2
Goodness-of-fit on F
1.122
1.197
Final R indices [I >
R1 = 0.0591, wR2 =
0.1440
R1 = 0.0519, wR2 =
0.1213
2sigma (I)]
R indices (all data)
R1 = 0.0722, wR2 =
R1 = 0.0576, wR2 =
0.1244
0
.1514
-3
-3
Largest diff. peak and
hole
0.526 and -0.397 e.Å
0.533 and -0.439 e.Å
a R1 = Fo – Fc / Fo and wR2 = { [w(F02 – Fc2)2]/
1
/2
[w(Fo2)2]}
2
3

Table 2. Structure refinement and crystal data for 5.
Empirical formula
Formula weight
Temperature
C H N O Zn
3
0
27
2
4.50
552.91
296(1) K
Wavelength
0.71073 Å
Crystal system
Space group
Monoclinic
C2/c
Unit cell dimensions
a = 29.017(6)
Å = 90°
b = 12.615(2)
Å =
1
00.401(2)°
c = 14.667(3)
Å =
9
0°
3
Volume
5280(2) Å
8
Z
3
Density (calculated)
Absorption coefficient
F(000)
1.391 Mg/m
-
1
0.971 mm
2296
0.42 × 0.16 × 0.10 mm
3
Crystal size
Theta range for data collection 2.68 to 27.00°
Index ranges
-36<=h<=36, -14<=k<=16,
18<=l<=18
-
Reflections collected
Independent reflections
Completeness to theta =
19220
5684 [R(int) = 0.0581]
98.4%
2
8.03°
Absorption correction
Semi-empirical from
equivalents
Max. and min. transmission
Data / restraints / parameters
0.9092 and 0.6859
5684 / 0 / 341
0.851
2
Goodness-of-fit on F
Final R indices [I > 2sigma
R1 = 0.0546, wR2 =
0.1425
(
I)]
2
4

R indices (all data)
R1 = 0.1619, wR2 =
.1740
0.270 and -0.324 e.Å
0
-3
Largest diff. peak and hole
a
R1 = Fo – Fc / Fo and wR2 = { [w(F02 –
1
/2
Fc2)2]/ [w(Fo2)2]}
2
5

Table 3. Physical properties and yield of zinc(II) complexes.
Compounds %Yield
m.p (°C)
147-149
Solubility
3
77
CHCl , CH OH, CH C(O)CH ,
3
3
3
3
DMSO
4
5
85
79
101
CHCl , CH OH
3
3
159-165
CH OH, CH C(O)CH , DMSO
3
3
3
2
6

Table 4. Hydrogen bonds for 3 [Å and °].
D-H...A
d(D-H)
d(H...A)
d(D...A)
<(DHA)
179(3)
N(2)-
H(1N2)...O(2)#1
0.819(10) 2.112(11) 2.931(4)
0.815(10) 2.090(15) 2.873(4)
0.811(10) 2.194(15) 2.971(4)
0.817(10) 2.140(17) 2.901(4)
N(2)-
H(2N2)...O(3)
161(3)
160(3)
155(3)
N(4)-
H(1N4)...O(4)#2
N(4)-
H(2N4)...O(1)
2
7

-
1
Table 5. Summary of principle peaks in the IR spectra of 3-5 (cm ).
Na-phenyl
acetate
Assignments
3
4
5
ν(C-H)ar
γ(C-H)
3025
3024
851
3057
3027
933,710
853
861
ν(C-H)alph
νas(N-H)
νs(N-H)
δ(NH2)
2000
2700
3341
3227
1619
661,698
1998
2800
-
-
-
-
-
-
-
-
-
-
-
-
(N-H)
wagging
ν(C-NH2)
ν(C-C)ring
-
1271
-
-
1496
1159
1223
1450
ν(C-C) +
1281,1186
1499,1360
1144,1100 1340,1221
ring
δ(CH)
ν(C-N)
ν(Zn-O)
ν(Zn-N)
-
-
-
1567
459
1515
421
1500
400
527
580
550
2
8

Table 6. UV-visible spectral data for the prepared complexes.
-
1
-1
Compounds
Zn-phenyl
λmax (nm)
214
Є (Lmol cm )
2280.3
202.9
2
2
59
65
203.68
3
4
296
7864.7
277
27471
19379
1594.4
2
3
92
25
5
201
23816
53062
31408
2
2
31
69
2
9