Synthesis, characterization, analgesic and anti-inflammation activity of new phthalazines and their Cu(II) and Zn(II) complexes

Article abstract of DOI:10.1007/s00044-015-1427-4

1,4-Dioxo-3, 4, 4e, 5, 10, 10a-hexahydro-1H-5,10-benzenobenzo [g] phthalazin-2-yl-thioamide [6a]; 1,4-dioxo-3, 4, 4e, 5, 10, 10a-hexahydro-1H-5, 10-benzenobenzo [g] phthalazin-2-yl-N-pyridylthioamide [6b] and 1,4-dioxo-3, 4, 4e, 5, 10, 10a-hexahydro-1H-5, 10-benzenobenzo[g]phthalazin-2-yl-N-ethylthioamide [6c] and their [Cu(6a-H)(OAc)], [Zn(6a-H)(OAc)], [Cu(6b-H)(H₂O)₂(OAc)]·3H₂O and [Zn(6b-H)(OAc)], [Cu₂(6c-H)](OAc)₃]·2H₂O and [Zn(6c-H)(OAc)] complexes have been synthesized via a reaction between phthalazinedione 6a-c derivatives and the acetate salt of Cu(II) or Zn(II). These compounds were characterized by elemental analysis, spectra (UV-Vis, IR, ¹H NMR, ¹³C NMR, ESR), conductance, thermal analysis and magnetic moments.

Full text of DOI:10.1007/s00044-015-1427-4

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-015-1427-4
ORIGINAL RESEARCH
Synthesis, characterization, analgesic and anti-inflammation
activity of new phthalazines and their Cu(II) and Zn(II) complexes
Yousery E. Sherif1,2 Moustfa A. Gouda1,3 Ahmed A. El-Asmy3,4
•
•
Received: 26 May 2015 / Accepted: 8 August 2015
Ó Springer Science+Business Media New York 2015
Abstract 1,4-Dioxo-3, 4, 4e, 5, 10, 10a-hexahydro-1H-
5,10-benzenobenzo [g] phthalazin-2-yl-thioamide [6a]; 1,4-
dioxo-3, 4, 4e, 5, 10, 10a-hexahydro-1H-5, 10-benzenobenzo
[g] phthalazin-2-yl-N-pyridylthioamide [6b] and 1,4-dioxo-3,
4, 4e, 5, 10, 10a-hexahydro-1H-5, 10-benzenobenzo[g]ph-
thalazin-2-yl-N-ethylthioamide [6c] and their [Cu(6a-
H)(OAc)], [Zn(6a-H)(OAc)], [Cu(6b-H)(H2O)2(OAc)]Á3H2O
and [Zn(6b-H)(OAc)], [Cu2(6c-H)](OAc)3]Á2H2O and
[Zn(6c-H)(OAc)] complexes have been synthesized via a
reaction between phthalazinedione 6a–c derivatives and the
acetate salt of Cu(II) or Zn(II). These compounds were
characterized by elemental analysis, spectra (UV–Vis, IR,
1H NMR, 13C NMR, ESR), conductance, thermal analysis
and magnetic moments.
Introduction
Arthritis is a family of musculoskeletal disorders consisting
of more than 100 different diseases or conditions that destroy
joints, bones, muscles, cartilage and other connective tissues,
hampering or halting physical movement (Lipsky, 2001).
Medications used to treat rheumatoid arthritis can be divided
into two groups: those that help relieve symptoms and reduce
inflammation (nonsteroidal anti-inflammatory drugs and
corticosteroids) and those that can modify the disease or put
it in remission (disease-modifying antirheumatic drugs and
biologic agents) (Hawkey, 1992). The analgesic effect of
NSAIDs is primarily the result of their inactivation of
cyclooxygenase: an enzyme that converts arachidonic acid
into eicosanoids such as prostaglandins and leukotrienes
(Celotti and Laufer, 2001). Two forms of cyclooxygenase
have been identified: COX-1, which exists in the stomach,
intestines, kidneys and platelets and COX-2, which expres-
sed as part of the inflammatory process (Battistini et al.,
1994). Ibuprofen is a non-selective inhibitor of cyclooxy-
genase and is available as both a prescription and over-the-
counter (OTC) product (Cryer and Feldman, 1998). A
number of heterocyclic compounds containing phthalazine
rings were associated with diverse pharmacological prop-
erties such as anticonvulsant (Grasso et al., 2000), car-
diotonic (Nomoto et al., 1990), antidiabetic and anti-
inflammatory (Dogruer et al., 2004). Also, phthalazines have
been reported to potentially inhibit serotonin reuptake and
are considered antidepression agents (Cashman et al., 2009).
Furthermore, heterocyclic compounds containing phtha-
lazinedione moiety (Fig. 1) are interest due to their ant
hypoxic and antipyretic agent (Jain and Vederas, 2004) and
HAV 3C inhibitor (Carling et al., 2004).
Keywords Phthalazine Á Cu(II) Á Zn(II) Á
Complexes, analgesic Á Anti-inflammatory
& Yousery E. Sherif
youserysherif@hotmail.com
1
Department of Chemistry, Faculty of Science and Arts, Ulla,
Taibah University, Fahd Street, Ulla,
El Madinah All Monwara, KSA
2
Department of Clinical Pharmacology, Faculty of Medicine,
Mansoura University, Mansoura, Egypt
3
Department of Chemistry, Faculty of Science, Mansoura
University, Mansoura, Egypt
4
The Cu(II) and Zn(II) complexes showed anti-inflam-
matory, analgesic and antirheumatic effects (Hosny and
Department of Chemistry, Faculty of Science, Kuwait
University, Kuwait City, Kuwait
123

Med Chem Res
Fig. 1 Heterocycles containing
the phthalazinedione moiety
Antihypoxic and antipyretic agent
HAV 3C inhibitor
Sherif, 2015; Jackson et al., 1978). Moreover, other trace
elements were used in the treatment of rheumatoid arthritis
including calcium (mainly in the form of calcium aspirin),
zinc and gold [Au(I) complexes of thiomalate, thioglucose,
thiopropanol or thiosulfate; Au(II) colloids and Au(III)
chloride]. A large proportion of gold complexes onto the
serum albumin in plasma and perhaps it have similar roles
to those of copper. However, since gold is not normally
found in humans, many series of researches have concen-
trated on copper (Jackson et al., 1978). Quantitative
observations concerning the anti-inflammatory role of
copper drug compounds have been made previously by
Sorenson (Sorenson, 1976) who reported that copper salts
of many acidic anti-inflammatory drugs are more effective
for reducing inflammation.
Shimadzu model 50 H instrument using 20 mg samples.
The nitrogen flow rate and heating were, respectively,
20 cm3/min and 10 °C/min at the National Research Cen-
ter, Dokki, Giza, Egypt. The magnetic measurements were
carried out on a Sherwood Scientific Magnetic Balance at
1
Mansoura University. The H NMR and 13C-NMR spectra
were obtained on
a
Bruker spectrophotometer at
(500)150 MHz, using TMS as an internal reference and
DMSO-d6 as solvent at the Chemistry Department, Faculty
of Science, King Abdul Aziz University, Saudi Arabia.
Synthesis of 1, 4-dioxo-3, 4, 4a, 5, 10-10-hexahydro-
1H-5, 10-benzo–benzo [g] phthalazin-2yl-thioamide)
(6a), 1,4-dioxo-3, 4, 4a, 5, 10-10a-hexahydro-1H-
5,10-benzenobenzo[g]phthalazin-2-yl-N-pyridin-2yl-
thioamide (6b) and 1,4-dioxo-3, 4, 4e, 5, 10, 10a-
hexahydro-1H-5, 10-benzenobenzo[g]-phthalazin-2-
yl-N-ethylthioamide (6c)
These biological data prompted us to synthesize some
new phthalazinedione copper and zinc complexes incor-
porating thioamide moiety, starting from dibenzobarallene
in order to investigate their anti-inflammatory and anal-
gesic activities.
Thiosemicarbazide (4a), 4-(pyridin-2yl)thiosemicarbazide
(4b) [5.07 g, 0.03 mol], 4-ethylthiosemicarbazide (4c)
[3.60 g, 0.03 mol] in dimethylformamide were heated
under reflux for 10 h. The reaction mixture was cooled then
poured in ice, and the separated product was filtered off,
dried and crystallized from benzene-ethanol to give:
6a–c (Khalil et al., 2009).
Materials and methods
All chemicals were of analytical grade and were used
without further purification. Melting points were recorded
on Gallen Camp electric melting point apparatus and were
uncorrected. Carbon and hydrogen content was determined
on a Microanalytical Unit of Cairo University. Molar
conductance measurements of the complexes (10-3
mol L-1) in DMSO solution were carried out with a con-
ductivity bridge YSI model 32. Metal analysis was carried
out by standard methods (Vogel, 1961). The IR spectra
were measured using KBr disks on a Mattson 5000 FTIR
spectrometer. The electronic spectra were recorded on UV2
Unicam UV/Vis spectrophotometer using 1-cm stoppered
silica cells. Powder ESR spectra were obtained in a 2-mm
quartz capillary at room temperature with a Bruker EMX
spectrometer working in the X-band (9.78 GHz) with
100 kHz modulation frequency. The microwave power and
modulation amplitudes were set at 1 m Wand 4G. The low
field signal was obtained after four scans with a tenfold
increase in the receiver again. The thermogravimetric
analysis measurements (TGA, DTG) were carried out at a
Synthesis of the metal (II) complexes (7–12)
A mixture of 6a, 6b or 6c (3 mmol) and the acetate salt of
Cu (II) or Zn (II) (3 mmol) in 25 mL absolute ethanol was
heated under reflux on a water bath for 6 h. The formed
precipitate was filtered off, washed with hot water, hot
ethanol and diethylether and finally dried to give [Cu(6a-
H)(OAc)] (7), [Zn(6a-H)(OAc)] (8), [Cu(6b-H)(H2O)2
(OAc)]Á3H2O, (11), [Zn(6b-H)(OAc)] (9) [Cu2(6c-
H)(OAc)3(H2O)2] (12) and [Zn(6c-H)(OAc)] (10).
Pharmacological testing
Eighty-four Sprague–Dawley rats (200–250 g) were
obtained from the animal house of Faculty of Medicine,
Mansoura University, and fed on a standard rat chow and
water ad libitum. Animal care and experiments were
123

Med Chem Res
Proximal joint (right ankle) mobilization tolerance
(pain scoring)
performed in accordance with the guidelines established by
the NIH Guide to the Care and Use of Laboratory Animals,
NIH publication no. 86–23. Rats were housed under similar
standard laboratory conditions. The animals were divided
into two main groups (non-arthritic control and arthritic
group). In the arthritic group, all rats had been inoculated
by the reagent of collagen–adjuvant arthritis into the left
paw pad. Rats which developed right paw arthritic mani-
festations after 45 days were divided into four groups:
arthritic control, piroxicam-treated zinc acetate, copper
acetate-treated, copper complex- and zinc complex-treated
groups. The compounds were given orally via gastric tube
daily for 7, 45 days after Freund’s injection of Collagen II-
arthritis. This is a modified form of the previous models
(Trentham et al., 1977). This model of collagen–adjuvant
arthritis (Waksman et al., 1960) is considered to be a
representative of rheumatoid arthritis or ankylosing
spondylitis in human. Collagen II–Freund’s adjuvant
emulsion (0.1 mL) was injected intradermal into the left
hind foot paw pad of each rat (if no arthritis developed
within 4 weeks, some of the animals were challenged by a
second inoculation). After 45 days, the systemic arthritis
developed in both hind paws (Wood et al., 1969). Most of
the compounds are insoluble in water and were suspended
in 0.5 % sodium carboxymethylcellulose [CMC]. The
determined doses were injected intraperitoneal. The doses
are calculated according to the reference (Ghosh and
Schild, 1971).
This mobilization tolerance was graded from 1 to 4. Degree
1 corresponds to tolerance of complete flexion 90°; degrees
2–4 correspond to increasing the degrees of maltolerance
according to a rat hind limb withdrawal, squeaking and
when the flexion becomes painful. Degree 4 corresponds to
squeaking with just initiation of flexion. Each of the six
non-arthritic, non-treated rats had a score of 1 (Ghosh and
Schild, 1971). This measurement was done at the seventh
day of drug treatment. The results were expressed as mean
SE. Multi regression analysis (one way ANOVA,
Newman-Keuls and F-test) test was used to compare more
than two groups Collagen-adjuvant arthritis model in rats.
p values B 0.05 were considered statistically significant
(Waynforth and Flecknell, 1992).
Results and discussion
Characterization of 6a, 6b and 6c and their Cu(II)
and Zn(II) complexes (7–12)
Scheme 1 describes the synthesis of the target compounds.
Dibenzobarallene (3) was prepared via heating of anthra-
cene (1) with maleic anhydride (2) in xylene under reflux
(Clar, 1931). Condensation of (3) with thiosemicarbazide
(6a), 4-(pyridin-2-yl) thiosemicarbazide (6b) or 4-ethylth-
iosemicarbazide (6c) in DMF produced phthalazinedione
6a (Khalil et al., 2009) 6b or 6c. These compounds were
Paw edema measurement: (Paw edema meter)
1
characterized by elemental analysis, IR, H NMR and MS.
The adjuvant-induced inflammation in the contralateral
paw pad (hind right paw pad) was measured by the paw
edema meter measurement of rat paw thickness joint
inflammation measurement. It was carried out for 45 days
after complete Freund’s adjuvant injection (Randall and
Selitto, 1957; Ward and Jones, 1962).
Reaction of 6a, 6b or 6c with zinc acetate or copper acetate
in ethanol produced [Cu(6a-H)(OAc)] (7), [Zn(6a-H)(OAc)]
(8), [Cu(6b-H)(H2O)2(OAc)]Á3H2O (11), [Zn(6b-H)(OAc)]
(9), [Cu2(6c-H)(OAc)3(H2O)2] (12) and [Zn[6c-H](OAc)]
(10). The analytical data and physical properties of the prepared
complexes are summarized in the experimental section. The
found and calculated % of C, H and M agree well and proved
the suggested formulae. The molar ratio (M/L) is suggested for
1:1 complexes (7–11) and 2:1 complex (12).
Pain tolerance measurement right paw pad pressure
tolerance
All the metal complexes are stable in air, insoluble in most
common organic solvents, but soluble in DMSO. Conduc-
tance, magnetic moments and melting points of the com-
plexes are given in Table 1. The molar conductance values
for complexes were found within the range 8.0–4.3
ohm-1 cm2 mol-1 of 1 9 10-3 mol L-1 DMSO solution, at
25 °C, reported for nonelectrolyte complexes (Geary, 1971).
For assessment of the analgesic activity of the used drugs,
pressure was applied by the analgesimeter on the rat pad
of the right paw. The pressure increased gradually (a
certain number of grams per second until the rat either
squeaks or tries to withdraw its limb). The pressure was
continuously monitored by a pointer moving along a lin-
ear scale. Increasing pressure tolerance of drug-treated
rats indicates analgesic activity of the administered drug
(Randall and Selitto, 1957; Ward and Jones, 1962). This
measurement was done at the seventh day of drug treat-
ment (45 days after complete Freund’s adjuvant
injection).
1
IR and H NMR data
The IR spectra of 6a, 6b and 6c (Scheme 1; Table 2) reveal
bands at 2544, 2451 or 2540 cm-1, due to m(SH), of the
123

Med Chem Res
Scheme 1 Synthesis of phthalazinediones 6a, 6b, 6c
Table 1 Physical properties and elemental analysis of 6a, 6b and 6c and their Cu(II) and Zn(II) complexes
Compound, formula
Color
Found (Calcd.) (%)
M.p., °C Magnetic
Conductance
moments BM X-1 cm2 mol-1
FW
C
H
Metal
–
6a
White
65.66 (65.31) 4.23
(4.33)
4.11
(3.64)
230
260
280
220
270
–
–
349.44
470.99
472.81
426.12
638.15
C19H15N3O2S
[Cu(6a-H)(OAc] (7)
C21H17N3O4SCu
[Zn(6a-H)(OAc)] (8)
C21H17N3O4SZn
6b
Light green
White
52.6
13.55
0.78
–
4.90
8.00
–
(53.55)
55.54
(13.50)
4.66 (4.44) 13.71
(13.83)
(53.35)
63.75
White
4.79
–
–
C24H18N4O2S
[Cu(6b-H)(H2O)]Á3H2O
(11)
(67.59)
47.93
(4.25)
5.01
Green
10.05
(9.99)
2.15
6.40
(48.93)
(4.73)
C
26H30N4O9SCu
[Zn(6b-H)(OAc)] (9)
26H20N4O9SZn
Yellowish white 57.41
(56.79)
4.57
11.80
(11.90)
–
295
260
286
299
–
4.30
549.89
377.47
734.73
499.88
C
(4.37)
5.69
6c
White
62.21
C21H19N3O2S
(66.88)
(5.07)
3.9
[Cu2(6c-H)(AOc)3]Á3H2O (12) Brawn
27H33N4O2SCu2
44.72
(44.13)
17.50
1.50
–
5.80
4.50
C
(4.53)
4.10
(17.70)
13.00
[Zn(6c-H)(OAc)] (10)
Yellowish white 54.52
(55.27)
C23H20N4O2SZn
(4.03)
(13.06)
thiol form of the three ligands. Moreover, the IR spectrum
of 6b shows bands at 1564, 635 and 428 cm-1 which are
assigned to m(C=Npyridine). These bands are important in
deciding whether the pyridine ring takes part in coordina-
tion or not. The bands at 1740 and 1701 cm-1 assigned to
m(C=O) remained more or less shifted in complexation
which indicates their inertness in coordination. The m(C=N)
band of the pyridine in [Cu(6b-H)(H2O)2(OAc)]Á3H2O (11)
is shifted after complexation to 1533 cm-1. The acetate
bands appeared at 1500 and 1357 cm-1. The t(SH) band
was disappeared due to its coordination by forming of S–
Cu or S–Zn bonds.
H)(OAc)](9), [Cu2(6c-H)(OAc)3(H2O)2](12) and [Zn(6c-
H)(OAc)](10) showed the disappearance of the SH band and
the shift of the CO groups to lower frequency. It is concluded
that the ligands behave as a mononegative bidentate coor-
dinating through the carbonyl oxygen and the thiol sulfur
(Scheme 2; Table 2). This suggestion is supported by the
following evidence (i) the disappearance of the band at
2540 cm-1 assigned to m(SH) indicating that this group is
taking part in coordination after displacement of hydrogen;
(ii) the shift of the band assigned to m(CO) to higher wave
number, (iii) the presence of (COamidic) group more or less
unaltered indicating that these groups do take part in coor-
dination, (iv) the spectra showed bands at 1481–1500,
1309–1338 or 1308–1414 cm-1 assigned to the mas and ms
The IR spectra of [Cu(6a-H)(OAc)](7), [Zn(6a-
H)(OAc)](8), [Cu(6b-H)(H2O)2(OAc)]Á3H2O(11), [Zn(6b-
123

Med Chem Res
Table 2 The most important IR bands of the ligands and their complexes
Compound
m(NH)
m(SH)
m(C=O)
m(C=N)
mas(AOc)
ms(AOc)
6a
3410
3248
3364
3204
3410
3311
3417
3450
3218
3261
3334
3417
2544
1735, 1724
1619
–
–
[Cu(6a-H)(OAc)] (7)
[Zn(6a-H)(OAc)] (8)
–
–
1727, 1707
1728, 1710
1612
1608
1481–1500
1465–1510
1309–1344
1304–1338
6b
2451
–
1740, 1701
1738, 1700
1604, 1628
1616
–
–
[Cu(6b-H)(H2O)2(OAc)]Á3H2O (11)
1483–1520
1309–1338
[Zn(6b-H)(OAc)] (9)
–
1736, 1700
1728, 1701
1725
1622, 1600
1617
1482–1510
1309–1341
–
6c
2540
–
–
[Cu2(6c-H)((OAc)3(H2O)2)]Á3H2O
(12)
1625
1482
1308–1340
[Zn(6c-H)(OAc)] (10)
3430
–
1738
1621
1485
1308–1322
Scheme 2 Synthesis of copper and zinc complexes 7–12
1H and 13C NMR
vibrations of the acetate group, respectively. The difference
between the two bands suggests the bidentate nature of the
acetate group (Cakir et al., 2002; Nakamoto, 1970) and the
bands in the region at 568, 454 and 439 cm-1 assigned to
m(Cu–O), m(Cu–N) and m(Cu–S), respectively (Atzei et al.,
2000). The spectrum of [Cu(6b-H)(H2O)2(OAc)]Á3H2O(11)
has an intense, broad band centered at 3417 cm-1, suggest-
ing that the water molecules are coordinate and hydrate
(Hafez et al., 1995a, b).
1
The H NMR spectrum of [Zn(6a -H)(OAc)] (8) (Table 3)
displayed two singlet signals at d = 1.84 and 7.42 ppm and
broadsinglet at11.2 ppm assignedtoCH3CO, NHandNHCO
protons, respectively. The spectrum of [Zn(6b-H)(OAc)] (9)
showedasingletsignalat1.78 ppmduetotheCH3COprotons
and a broad singlet signal at 10.95 ppm due to the NH–CO
proton. Moreover, [Zn (6c-H)(OAc)] (10) displayed a singlet
123

Med Chem Res
Table 3 NMR spectra of ligands and their complexes
Compound
Spectra
6a
1H-NMR (DMSO-d6): d ppm 3.29 (br, 2H, C4a–H, C10a–H), 4.88 (br, 2H, C5–H, C10–H), 5.98 (br, 1H, NHC=S),
7.12–7.79 (m, 12H, Ar–H), 8.33 (br, s, 1H, NH) 10.95 (br, s, 1H, NHC=O), 13C-NMR(DMSO-d6) dppm:173.2(2C,
C1,C4), 170.6-(C=NH),141.0(2C, C5a, C5a–), 139.0(2C, C9a, C9a–), 127.4(2C, C7, C7–), 126.8(2C, C8, C8–),
125.0(2C, C6, C6–),124.2(2C, C9, C9–), 48.1(C4a), 45.2(C10a), 45.0(C10), 44.8(C5)
6b
6c
1H-NMR (DMSO): dppm 3.29(brs, 2H, C4a–H, C10a–H), 4.88(brs, 2H, C5–H, C10–H), 5.98(brs, 1HNHC=S),
7.12–7.79 (m, 12H, Ar–H), 8.33 (br, s, 1H,NH) 10.95 (br, s, 1H, NHC=O), EIMS (m/z) (%) 408 (M ? –(H2O) 0.3),
377 (1.1), 290 (19.4), 230 (1.2), 204 (2.3), 202 (1.2), 178 (100),152 (8.1), 128(1.6), 94 (2.5) and 71 (0.5)
1H-(DMSO-d6): d ppm 1.22 (t, 3H, CH3), 3.29 (br, s, 2H, C4a-H, C10a-H), 4.76 (s, br, 2H, C5–H, C10–H), 7.10-7.40
(m, 8H, Ar–H), 7.95 (br, s, 1H, NH), 9.12 (br, s, 1H, NHCO), 9.41 (br, 1H, SH). 13C NMR (DMSO-d6): d ppm
173.78 (C1), 173.50 (C4), 141.32(C5a), 141.29(C5a–), 139.12(C=S), 138.58(C9a–), 138.54(C9a–),126.9(C6),
126.65(C6–), 126.57(C9), 126.52(C9–), 124.78(C7), 124.72(C7–), 124.14(C8), 124.13(C8–), 45.00(C4a),
44.91(C10a), 40.35 (CH2), 39.65 (C10), 39.51(C5), 13.89(CH3). EIMS (m/z) (%) 357 (M?, 2.6), 318 (2.9), 290
(4.0), 259 (8.6), 231 (4.0), 202 (8.0), 178 (100),152 (9.3), 112 (4.0), 82 (5.3) and 55 (3.3)
[Zn(6a-H)(OAc)] (7)
1H-NMR (DMSO-d6): d ppm 1.95(s, 3H, CH3), 3.20 (br, s, 2H, C4a-H, C10a-H), 4.76 (brs, 2H, C5–H, C10–H),
7.16–7.40 (m, 8H, ArH), 7.67 (brs, 1H, NH), 11.20 (brs, 1H, NHCO). 13C– NMR(DMSO-d6): d ppm. 172.2 (C1),
170.1(C4), 169.8(CO acetate), 169.2(C=N), 142.3(C 5a), 142.1(C5a–), 141.6(C9a), 141.0(C9a–), 127.4(C7),
127.2(C7–), 126.8 (2C, C8,C8–),125.6 (2C, C6,C6–), 125.0(C9), 124.2 (C9–), 48.3(C4a),46.2(C10a), 45.1 (C10),
44.8 (C5), 23.9 (CH3 acetate)
[Zn(6b-H)(OAc)] (9)
Zn(6c-H)(OAc)] (10)
1H-NMR(DMSO-d6): d ppm. 1.87(s, 3H, CH3–CO), 3.42(brs, 2H, C4a-H, C10a-H),4.72(brs, 2H, C5–H, C10–H),
7.03–7.39(m, 12H, ArH),10.95 (brs, 1H, NH–CO)
1H-NMR(DMSO-d6): d ppm. 1.26 (t, 3H, CH3), 1.98(s, 3H, CH3(acetate), 3.20 (br, s, 2H, C4a-H, C10a-H), 4.77(s, br,
2H, C5–H, C10–H), 7.15–7.40(m, 8H, Ar–H), 8.02(br, s, 1H, NH), 9.61 (br, s, 1H, NHCO). 170.7 (C1), 168.9 (CO,
acetate), 168.8(C4) 141.3(C5a), 141.0 (C5a–), 138.0 (C9a–), 137.8 (C9a–), 127.1 (C6), 127.0(C6–), 126.6(C9),
126.5(C9–), 125.1 (C7), 124.7 (C7–), 124.1 (C8), 124.0(C8–), 44.9(C4a), 44.8 (C10a), 40.7 (CH2), 39.8 (C10),
39.7(C5), 23.7 (CH3, acetate), 13.9(CH3)
signal for the three protons of CH3CO at 1.94 ppm and broad
singlet signal for the proton of NH–CO at 10.83.
d9 systems with the presence of one unpaired electron
(Hafez et al., 1995a, b).
The 13C NMR spectrum of [Zn(6a-H)(OAc)] (8) has
signals at d = 170.1 (C4); 169.8 (CO acetate); 169.2 (C=N)
and 23.9 (CH3 acetate). Also, the 13C NMR of [Zn (6c-
H)(OAc)] (9) showed peaks at 168.9 (CO acetate), 168.8
(C4), 40.7 (CH2), 23.7 (CH3, acetate), 13.9 (CH3).
The spectrum of [Cu2(6c-H)(OAc)3(H2O)2](12) in Nujol
showed a broad band at 13,000 cm-1 assigned to the
2B1g ? 2A1g and B1g ? Eg transitions in a square-pla-
nar geometry around the first atom (Hafez et al., 1995a, b).
The spectrum showed also another band at 18,380 cm-1
assigned to a distorted octahedral structure around the
second copper atom. The bands recorded at 25,905 and
17,920 cm-1 are suggested to LMCT and MLTC (Singh
et al., 1990). The magnetic moment value (1.5 BM) is
subnormal due to the presence Cu…Cu interaction (El-
Gammal, 2010).
2
2
Electronic spectra and Magnetic Measurements
The electronic spectrum of [Cu(6a-H)(OAc)](7) in Nujol
showed a broad band at 13,000 cm-1 assigned to the
2
2B1g ? A1g transition in a square-planar geometry
(Lever, 1986). The band recorded at 25,905 cm-1 is
assigned to LMCT. The shoulder at 17,920 cm-1 is
assigned to MLCT (Cu–p orbital of the ligand) (Cotton and
Wilkinson, 1980). The magnetic moment (0.78 BM) of
[Cu(6a-H)(OAc)] is lower than that reported for the d9
system. The subnormal moment is due to strong interaction
between the metal ions in the complex particles (Hafez
et al., 1995a, b).
ESR spectra of the copper complexes
ESR spectra of the complexes were recorded in the solid
state to gather information about their geometry and to
determine the magnetic interaction in the metal complexes.
The spin Hamiltonian parameters of the complexes were
calculated and are summarized in Table 4.
In the spectrum of [Cu(6b-H)(H2O)2(OAc)]Á3H2O(11),
the band at 1768 cm-1 indicates a distorted octahedral
structure. The band at 2451 cm-1 is assigned to LMCT. Its
magnetic moment value (2.15 B.M) lies in the range of the
The room temperature solid state ESR spectra of the
copper complexes exhibit an axially symmetric g-tensor
parameters with g|| [ g\ [ 2.0023, indicating that the
copper site has a d2x - dy2 ground state characteristic of
123

Med Chem Res
Table 4 ESR data of the Cu(II) complexes and their magnetic moment at room temperature
g\
gk
G
leff.t, BM
[Cu(6a-H)(OAc)] (7)
2.06
2.06
2.09
2.25
1.50
4.17
0.98
2.15
[Cu(6b-H)(OAc)(H2O)2]Á3H2O
(11)
[Cu2(6c-H))(OAc)3(H2O)2] (12)
2.05
2.11
2.20
1.50
Table 5 Thermoanalytical results (TGA) of M(II) complexes
Compound
Decomposition Temperature
step
Mass loss
found %
Mass loss
(Calcd. %)
Assignment
range (°C)
[Cu(6a-H)(OAc)] (7)
1st
50.0–180.0
200.0–260.0
260.0–300.0
300.0–480.0
Above 480.0
50.0–180.0
180.0–480.0
4.6
(4.5)
Loss of NH3 ? 2H2
2nd
3rd
15.6
26.5
18.3
35
(16.1)
(26.3)
(18.4)
(34.7)
(3.2)
Loss of (benzyl C6H4)
C
10H4(C6H4 ? C4H4)
4th
C2O3N2S(CH3 ? N2 ? CS)
CuC2O4 ? C
Residual
1st
[Zn(6a-H)(OAc)] (8)
3.5
Loss of NH
2nd
64.5
(65.0)
Loss of
C16H12 ? N2 ? C2H4 ? CH3COO
3rd
480.0–730.0
Above 730.0
50.0–180.0
180.0–206.0
11.3
20.6
1.06
26.0
(11.6)
(20.3)
(1.4)
Loss of 2CO
ZnS
Residual
1st
[Cu(6b-H)(H2O)2(OAc]Á3H2O (11)
Loss of ‘H2O
2nd
(26.0)
Loss of C7H8O5
(CO3 ? 2H2O ? benzyl C6H4)
3rd
206.0–328.0
23.3
(23.3)
Loss of C7H9 7/2O (benzyl C6H4 ? 5/
2H2O ? CO)
4th
328.0–418.0
Above 418.0
50.0–180.0
180.0–371.0
15.2
34.5
8.2
(15.3)
(33.9)
8.2
Loss of C5H9N2 (pyridyl NH ? 2H2)
CuC7H4 N2S
Residual
1st
[Zn(6b-H) OAc] (9)
Loss of H2 ? CH3CO
Loss of
2nd
49.34
43.34
C19H14ON(C14H8 ? C5H4N ? H2O)
3rd
371.0–500.0
500.0–750.0
Above 750.0
60–180 °C
190–270 °C
270–298 °C
298–680 °C
14.2
7.9
14.5
Loss of C4H2N2 (C4H2 ? N2)
4th
7.9
CS
Residual
1st
20
19.6
Zn ? CO2
Loss –2H2O
–C12H8 ? 3(CH3CO–)
–C5H5ON
–N2H4
[Cu2(6c-H)(OAc)3(H2O)2] (12)
5.0
(3.4 %)
40.4
2nd
3rd
40.8
13.2
9.9
13.2
4th
(10.6)
Cu2C4O4S
CH3
[Zn(6c-H) OAc] (10)
1st
110–189
190–326
Residue
3
3.3
81
2nd
3rd
83
C23H21N3O4S ? CO
ZnO
16.3
square-planar or octahedral stereochemistry (Speier et al.,
1996).
g = 2.06 attributable to the dipolar broadening and
enhanced spin lattice relaxation.
The calculated G values for [Cu(6a-H)(OAc)](7) and
[Cu2(6c-H)(OAc)3(H2O)2]Á3H2O(12) are less than 4, sug-
gesting copper–copper exchange interactions. The ESR
spectrum of [Cu(6b-H)(OAc)(H2O)2]Á3H2O(11) exhibits
broad single line, nearly isotropic signal centered at
Thermal analysis
To establish the proposed formula for the complexes, the
thermogravimetric analysis (TGA) was carried out under N2.
123

Med Chem Res
Table 6 Influence of copper acetate, piroxicam, 6a, 6b, 6c and their complexes on analgesic effect and inflammation(edema thickness) in
adjuvant-induced rheumatoid arthritis model in rats (M SE), n number of rats = 6
Group
Dose (mg 200 g-1
)
Analgesic effect
Pain tolerance
Inflammation
Edema thickness
Pain scoring
1. Negative control
2. Positive control
3. Piroxicam
[SCMC] Solvent
10.50 0.56
3.92 0.3¥
1.00 0.00
2.00 0.00
[SCMC] Solvent
3.83 0.17¥
2.50 0.43¥É
2.5 0.22¥
3.53 0.67¥
4.33 0.11¥
4.17 0.42¥
4.00 0.22¥
4.50 0.22¥
6.00 0.22¥ÉÓÒ
4.33 0.18¥k
6.00 0.40¥ÉÓÒ
4.75 0.22¥
3.85 0.34¥
3.33 0.33¥
3.17 0.31¥
4.35 0.22¥
0.36
0.22
0.22
1.10
0.36
0.96
0.96
1.8
4.08 0.15¥É
4.00 0.36¥
5.00 0.45¥
4.83 0.40¥
5.00 0.31¥
2.28 0.28¥
3.50 0.67¥
3.25 0.56¥
5.00 0.65¥
3.00 0.36¥
4.25 0.11¥
4.83 0.40¥
4. Copper acetate
5. Zinc acetate
1.83 0.31É
3.00 0.36¥
2.83 0.31¥
1.67 0.21ÉØ
3.67 0.31¥
2.67 0.21¥
3.50 0.34¥Ò
2.67 0.21¥
3.33 0.21¥
1.67 0.21ÉØ
6. 6a
7. [Cu(6a-H)(OAc)] (7)
8. [Zn(6b-H)(OAc)] (8)
9. 6b
10. Cu(6b-H) (H2O)2 Ac].3H2O (11)
11. [Zn(6b-H) OAc] (9)
12. 6c
1.04
0.93
2.2
13. [Cu2(6c-H)(OAc)3(H2O)] (12)
14. [Zn(6c-H)(OAc)] (10)
1.03
SCMC 0.5 % sodium carboxymethyl cellulose
¥ P \ 0.01 vs non-arthritic control É P \ 0.01 vs arthritic control § P \ 0.01 vs piroxicam
Ò
Ó P \ 0.01 vs copper acetate P \ 0.01 vs zinc acetate Ø P \ 0.01 vs [6a]
} P \ 0.01 vs [6b] k P \ 0.01 vs [Cu(6a-H)OAc] (21)
The maximum temperature values, Tmax/°C, together with
the corresponding weight loss for each step of decomposi-
tion are given in Table 5 together with its theoretical %.
The TGA curve of [Cu(6a-H)(OAc)](7) showed the first
step at 50–180 °C with loss of NH3 ? 2H2 (Found 4.6 %
(Calcd. 4.5 %). The second step at 180–260 °C is corre-
sponding to the loss of C6H4 (Found 15.6; Calcd. 16.1 %).
The third step is due to the loss of C10H4 at 260–300 °C
with 26.5 % (Calcd. 26.3 %). The weight loss in the fourth
step is corresponding to the removal of C2O3N2S. The
residue at temperature [480 °C is CuC2O4 ? C.
The TGA thermogram of [Zn(6a-H)(OAc)] (8) showed
the first step at 50–180 °C due to the loss of CH3 (Found
3.5 %; Calcd. 3.2 %). The second step lies at 180–480 °C
corresponding to loss of C16H12 ? N2 ? C2H4 ? CH3COO
(Found 64.5 % Calcd. (65.0 %). The next step corresponds
to the loss of 2CO at 480–730 °C (11.3 %, Cacd. 11.6 %).
The last step at 730 °C corresponds to ZnS as residue.
The TGA curves (TGA and DTG) of [Cu(6b-
H)(OAc)(H2O)2]Á3H2O](11) displayed decomposition at
50–180 °C corresponding to the loss of ‘H2O [1.06 %
(1.4 %]. The second step at 180–206 °C is corresponding
to the loss of C7H8O5 (CO2 ? 2H2O ? C6H4) [26.0 %
(Calcd. 26.0 %]. The third step corresponds to the loss of
C7H9O3.5 at 206–328 °C [23.3 % (23.3 %)]. The fourth
step corresponds to the loss of C5H9N2(pyridyl)NH ? 2H2)
at 328–418 °C [15.2 % (15.3 %)]. The last step ([418 °C)
corresponds to residue CuC7H4O2SN2) [34.5 % (33.9 %).
The TGA of [Zn(6b-H)(OAc)](9) showed one decom-
position step at 50–180 °C due to the removal of H2 ?
CH3CO (8.2 %, Calcd. 8.2 %). In the temperature range
180–371 °C, C19H14ON(C14H8 ? C5H4N ? H2O) is lost
with 49.34 % Calcd. 43.34 %). The third step is due to the
loss of C7H9 O3.5 at 371–500 °C with 14.2 % loss (Calcd.
14.5 %). The fourth step corresponds to the loss of CS at
500–750 °C, 7.5 % which is close to the calculated 7.5 %
leaving residue (Zn ? CO2).
The thermogram of [Cu2(6c-H)(OAc)3(H2O)2](12)
indicates the loss of one hydrated water at 60–180 °C. It
showed also the decomposition of the coordinated ligands
in three successive stages corresponding to two coordinated
water, three coordinated acetates and the organic ligand
without two carbonate molecules at 180–750 °C.
The TGA and DTG of [Zn(6c-H)(OAc)](10) showed the
decomposition at 110–189; 190–326 and [326 °C due to
rupture of CH3 [3.0 % (3.3 % theoretical)]; C23H21N3O4
S ? CO [83 % (calculated 81 %)] and the residue ZnO2
[16.3 % (19.6 %)].
Anti-inflammatory and analgesic effects of the ligands
and their complexes
As shown in Table 6, piroxicam was able to modify the
rheumatoid index (RI), pain tolerance and pain scoring
positively. On the other hand, the ligands and their Cu(II)
and Zn(II) complexes showed different degrees of
123

Med Chem Res
2, alpha 3, and alpha 5-subtype binding selectivity over alpha 1.
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