Synthesis of new transition metal complexes of 1H-perimidine derivatives having antimicrobial and anti-inflammatory activities

Article abstract of DOI:10.1007/s11164-011-0482-9

New series of 1H-perimidine-2-thiol derivatives and (2-substituted- 1Hperimidin- 1-yl)ethane-1,2-dione derivatives and their ligands (C ₂₄H₁₄N₄S₂O₂) H ₂L¹ and (C₂₆H₁₈N₄S ₂O₂) H₂L² have been synthesized with transition metal ions, e.g., Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized compounds and their complexes were characterized by elemental analysis, ¹H NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory effects against some bacterial strains by the disc diffusion method. On the other hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity. Springer Science+Business Media B.V. 2012.

Full text of DOI:10.1007/s11164-011-0482-9

Res Chem Intermed (2012) 38:1527–1550
DOI 10.1007/s11164-011-0482-9
Synthesis of new transition metal complexes
of 1H-perimidine derivatives having antimicrobial
and anti-inflammatory activities
•
Fatma A. Bassyouni Sherifa M. Abu-Bakr
•
•
Khaled H. Hegab Wafaa El-Eraky
•
•
Ahmed A. El Beih Mohamed E. Abdel Rehim
Received: 27 September 2011 / Accepted: 29 December 2011 / Published online: 18 February 2012
Ó Springer Science+Business Media B.V. 2012
Abstract New series of 1H-perimidine-2-thiol derivatives and (2-substituted-1H-
perimidin-1-yl)ethane-1,2-dione derivatives and their ligands (C24H14N4S2O2) H2L1
and (C26H18N4S2O2) H2L2 have been synthesized with transition metal ions, e.g.,
Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated
for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized
compounds and their complexes were characterized by elemental analysis, 1H
NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic
spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory
F. A. Bassyouni (&) ꢀ A. A. El Beih
Chemistry Department of Natural and Microbial Products and Pharmaceutical Research
Department, Center of Excellence for Advanced Sciences, National Research Centre,
Cairo 12622, Egypt
e-mail: fatma.nrc@hotmail.com
A. A. El Beih
e-mail: aae2eg@yahoo.com
S. M. Abu-Bakr
Chemistry Department of Natural and Microbial Products, National Research Centre,
Cairo 12622, Egypt
e-mail: sherifakandel@hotmail.com
K. H. Hegab
Department of Inorganic Chemistry and Pharmaceutical Research Department, Center of Excellence
for Advanced Sciences, National Research Centre, Cairo 12622, Egypt
e-mail: kh19salm@hotmail.com
W. El-Eraky
Department of Pharmacology, National Research Centre, Cairo 12622, Egypt
e-mail: wafaa_nrc@yahoo.com
M. E. A. Rehim
Department of Analytical Chemistry, Stockholm University, 10691 Stockholm, Sweden
e-mail: mohamed.abdel-rehim@anchem.su.se
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effects against some bacterial strains by the disc diffusion method. On the other
hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity.
Keywords Mercapto-1H-perimidine derivatives ꢀ Quinoxaline derivatives ꢀ
Transition metal complexes ꢀ Antiinflammatory activity ꢀ Antimicrobial activity
Introduction
Perimidine derivatives are of wide interest because of their diverse biological
activities and chemical application. Several classical synthetic methods have been
reported for synthesis of perimidine derivatives. The most widely used method for
preparation of perimidine is the cyclocondensation reaction of 1,8-diaminonaph-
thalene with carboxylic acids under microwave irradiation [1–4]. Multi-nuclear
N-heterocyclic compounds like perimidines are of wide interest because they
exhibit a diverse range of biological activities [5–8]. The most commonly method
for the preparation of perimidines is the condensation reaction of 1,8-diamino-
naphthalene with a carbonyl group, which needs special reagents or force reaction
conditions. However, because of the continuing interest in this field, investigation
into simple methods for the synthesis of perimidines is important [2, 9–12].
Substituted naphthalene and their derivatives show a variety of biological activity,
such as antihypertensive, 1,2B-adrenergic antagonists, Ca2? channel blocker,
antitumor, antifungal, and antiviral [13–16].
Moreover, there is a considerable interest in the pharmacological of heterocyclic
ligand and their metal chelates [17, 18]. In general, nitrogen- and sulfur-containing
organic compounds and their metal complexes display a wide range of biological
activity such as antitumor, antibacterial, antifungal, and antiviral [19–24].
Motivated by the afore-mentioned findings and in a continuation of our interest
in the synthesis of a wide range of heterocyclic systems for biological screening
programmed in our laboratory [25–27], we describe here a facile synthesis of some
new 1H-perimidin derivatives, 1,2-bis(2-mercapto-1H-perimidin-1-yl)ethane-1,2-
dione derivatives, and 1,2-bis(2-(mercaptomethyl)-1H-perimidin-1-yl)ethane-1,2-
dione derivatives with their new transition metal ion complexes aiming to study
their antibacterial, analgesic, and anti-inflammatory activities in order to get a new
compounds that could be optimized for potent analgesic, anti-inflammatory, and
antibacterial agents.
Experimental
Chemistry
All melting points were measured on a Gallenkamp melting point apparatus and are
uncorrected. The IR spectra (4,000–400 cm-1) were recorded using KBr pellets in a
Jasco FT/IR 300 E Fourier transform infrared spectrophotometer. The NMR spectra
1
were recorded on a Joel HNMR and 13C NMR spectrometer (500 MHz) were run
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Synthesis of new transition metal complexes
1529
in dimethylsulphoxide (DMSO-d6). Chemical shifts were related to that of the
solvent. Mass spectra were recorded on Joel GC/MS mass spectrometer at 70 eV.
Elemental analyses were carried out at the Micro analytical Center of Cairo
University, Giza, Egypt. Molar conductance was measured at room temperature on
electronic conductivity model 19000-05 (USA). The electronic absorption spectra
were recorded using a Shimadzu UV-240 UV–Visible recording spectrometer.
Thermo-gravimetric analyses were carried out using a DTA-7 and TGA-7 perkin
Elmer 7 series thermal analyses system. The magnetic moments were measured
using Gouy method with Hg [Co (SCN)4] as calibrate, National Research Center,
Cairo, Egypt. Follow-up of the reactions and checking the purity of the compounds
was made by TLC on silica gel pre-coated aluminum sheets (Type 60 F254; Merck,
Germany).
Synthesis of 1H-perimidine-2-thiol (1)
To a solution of ethanolic potassium hydroxide (50 mL of 0.5% KOH) and 1,8-
diaminonaphthalene (10 mmol) in 25 mL of ethanol, carbon disulfide (10 mmol)
was added dropwise, and the contents were refluxed with stirring for 6 h. Then, the
mixture was left to cool at room temperature overnight. The solid product so formed
was filtered off, washed with water, and recrystallized from ethyl acetate, yielding
68% of product 1. Mp.: 244–246 °C.
1H-NMR (500 MHz, DMSO): d = 3.75 (1H, s, SH), 7.20–7.55 (6H, m, Ar–H),
11.33 (1H, s, NH, D2O-exchangeable). IR (KBr) cm-1 : v = 3,323 (NH), 2,500
(SH), 1,645 (C=N). MS: m/z = 199 [M? -1,100%]. Anal. Calcd for
C11H8N2S: = C, 65.98; H, 4.03; N, 13.99; S, 16.01. Found: C, 65.90; H, 4.08; N,
13.95; S, 16.05.
Synthesis of (1H-perimidine-2-yl)methanethiol (6)
1,8-Diaminonaphthalene (0.5 mol) and thioglycolic acid (0.5 mol) were added to
4 N HCl (100 mL) and contents were refluxed with stirring for 5 h. The mixture
was treated with aqueous sodium bicarbonate solution until pH 9, and the
precipitated solid was filtered off, washed with ether, and recrystallized from ethyl
acetate, yielding 72% of product 6, Mp.: 260–262 °C.
1H-NMR (500 MHz, DMSO): d = 3.68 (2H, d, CH2S), 3.85 (1H, s, CH2SH,
D2O-exchangeable), 7.22–7.55 (6H, m, Ar0H), 10.22 (1H, s, NH, D2O-exchange-
able). IR (KBr) cm-1 : v = 3,396 (NH), 2,450 (SH), 1,645 (C=N). MS: m/z = 214
[M?, 60%]. Anal. Calcd for C12H10N2S: C, 67.26; H, 4.70; N, 13.07; S, 14.96.
Found: C, 67.22; H, 4.65; N, 12.98; S, 14.92.
Reaction of 1H-perimidine-2-thiol (1) or 1H-perimidine-2-ylmethanethiol
(6)with benzoyl chloride: general procedure for synthesis of (2) and (7)
To a solution of compound 1 or 6 (0.01 mol) in dry acetone (25 mL), and K2CO3
(0.02 mol), then benzoyl chloride (0.02 mol) was added slowly with stirring for
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15 min. After addition was completed, the mixture was stirred for 3 h at room
temperature, then the mixture was poured on ice/water, and the precipitate formed
was collected by filtration, washed with water, ethanol and crystallized from ethyl
acetate, yielding 74% of product 2. Mp.: 255–257 °C and yielding 70% of 7. Mp.:
227–229 °C.
1H-perimidin-2-yl-benzothioate (2)
1H-NMR (500 MHz, DMSO): d = 6.77–6.90 (5H, m, Ar–H), 7.20–7.55 (6H, m,
Ar–H), 11.30 (1H, s, NH, D2O-exchangeable). IR (KBr) cm-1 : v = 3,323 (NH),
1,710 (C=O), 1,610 (C=N). MS: m/z = 304 [M?, 49%]. Anal. Calcd for
C18H12N2OS: C, 71.03; H, 3.97; N, 9.20; S, 10.54. Found: C, 71.08; H, 3.94; N,
9.16; S, 10.50.
(1H-perimidin-2-yl) methyl benzothioate (7)
1H-NMR (500 MHz, DMSO): d = 3.90 (2H, s, CH2S), 6.86–7.00 (5H, m, Ar–H),
7.20–7.65 (6H, m, Ar–H), 11.35 (1H, s, NH, D2O-exchangeable). IR (KBr) cm-1
:
v = 3,378 (NH), 1,725 (C=O), 1,641 (C=N). MS: m/z = 318 [M?, 31%]. Anal.
Calcd for C19H14N2O S: C, 71.67; H, 4.43; N, 8.80; S, 10.07. Found: C, 71.63.; H,
4.40; N, 8.88; S, 10.05.
Reaction of (1H-perimidin-2-yl) benzothioate (2) or [(1H-perimidin-2-yl)
methyl –benzothioate (7) with sodium borohydrid (NaBH4): general procedure
for preparation of compound (3) and (8)
Sodium borohydride (8.1 mmol) was added slowly to a solution of (1H-perimidin-
2-yl)-benzothioate (2) or (1H-perimidin-2-yl)methyl) benzothiaoate (7) (2.7 mmol)
in 25 mL of chloroform at 0 °C followed by stirring for 30 min at room
temperature; water (50 mL) was added to the reaction mixture and extracted with
ethyl acetate. The organic layer was evaporated, yielding 62% of product 3 Mp.:
269–271 °C or yielding 65% of product 8. Mp.: 262–264 °C.
(1H-perimidin-2-ylthio)(phenyl) methanol (3)
1H-NMR (500 MHz, DMSO): d = 5.70 (1H, s, CH), 6.87–7.00 (5H, m, Ar–H),
7.22–7.55 (6H, m, Ar–H), 11.20 (1H, s, NH, D2O-exchangeable), 12.90 (1H, s, OH,
D2O-exchangeable). IR (KBr) cm-1 : v = 3,396 (OH), 3,290 (NH), 1,645 (C=N).
MS: m/z = 306 [M?, 35%]. Anal. Calcd. for C18H14N2OS: C, 70.65; H, 4.61; N,
9.14; S, 10.47. Found: C, 70.61; H, 4. 65; N, 9.11; S, 10.44.
((1H-perimidin-2-yl)methylthio) (phenyl)methanol (8)
1H-NMR (500 MHz, DMSO): d = 3.80 (2H, s, CH2S), 5.65 (IH, d, CH), 6.80–7.00
(5H, m, Ar–H), 7.22–7.65 (6H, m, Ar–H), 11.30 (1H, s, NH, D2O-exchangeable),
12.90 (1H, s, OH, D2O-exchangeable). IR (KBr) cm-1 : v = 3,390 (OH), 3,280
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Synthesis of new transition metal complexes
1531
(NH), 1,647 (C=N). MS m/z: 320 [M?, 30%]. Anal. Calcd. for C19H16N2OS: C,
71.22; H, 5.03; N, 8.74; S, 10.01. Found: C, 71.18.; H, 4.96; N, 8.78; S, 10.05.
General procedures for synthesis of (1H-perimidin-2-
ylsulfonyl)(phenyl)methanol (4) and (1H-perimidin-2-yl)methysulfonyl)
(phenyl) methanol (9)
Compound 3 or 8 (10 mmol) was dissolved in glacial acetic acid (5 mL) at 80 °C
and then 30% hydrogen peroxide (2 mL) was added. Further additions of 30%
hydrogen peroxide (2 mL) were made every 15 min during the first 2 h, and then,
after 3 h, 3 mL of 30% hydrogen peroxide was added and refluxed for 24 h. The
reaction was allowed to cool to room temperature, and was then poured onto water
(50 mL), and the solid formed collected by filtration, washed with water, ethanol,
and crystallized from ethyl acetate, yielding 62% of product 4. Mp.: 276–278 °C
and yielding 65% of product 9, Mp.: 290–292 °C.
(1H-perimidin-2-yl)sulfony)(phenyl)methanol (4)
1H-NMR (500 MHz, DMSO): d = 5.70 (1H, s, CH), 6.85–7.00 (5H, m, Ar–H),
7.22–7.65 (6H, m, Ar–H), 11.20 (1H, s, NH, D2O-exchangeable); 12.90 (1H, s, OH,
D2O-exchangeable); IR (KBr) cm-1 : v = 3,395 (OH), 3,280 (NH), 1,645 (C=N).
MS: m/z = 338 [M?, 40%]. Anal. Calcd for C18H14N2O3S: C, 63.89; H, 4.17; N,
8.28; S, 9.48. Found: C, 63.89; H, 4.23; N, 8.32; S, 10.55.
((1H-perimidin-2-yl) methyl) sulfonyl)(phenyl) methanol (9)
1H-NMR (500 MHz, DMSO): d = 3.60 (2H, s, CH2S), 5.75 (IH, d, CH), 6.80–7.00
(5H, m, Ar–H), 7.22–7.6 5 (6H, m, Ar–H), 11.50 (1H, s, NH, D2O-exchangeable);
12.80 (1H, s, OH, D2O-exchangeable). IR (KBr) cm-1 : v = 3,390 (OH), 3,280
(NH), 1,647 (C=N), 1,320 (SO2). MS: m/z = 339 [M?, 25%]. Anal. Calcd. for
C18H15N2O3S: C; 63.70; H, 4.45; N, 8. 25; S, 9.45. Found: C, 63.55; H, 4.43; N,
8.28; S, 9.50.
General procedures for methylation of (1H-perimidin-2-yl)sulfonyl)
(phenyl)methanol (4) and ((1H-perimidin-2-yl)methyl)sulfonyl)(phenyl)
methanol (9): synthesis of compound (5) and (10)
To a solution of [(1H-perimidin-2-ylsulfonyl)(phenyl)methanol (4) or [(1H-perimi-
din-2-yl)methylsulfonyl)(phenyl)methanol (9) (1 mmol) dissolved in acetone
(30 mL), potassium carbonate (2 mmol), then excess of methyl iodide (2 mmol),
was added portionwise with stirring over a period of 10 min and then refluxed for
6–7 h. The reaction mixture was allowed to cool to room temperature and the solid
product that formed was collected by filtration, washed with water, and dried and
recrystallized from ethyl acetate, yielding 66% of product 5, Mp.: 286–288 °C and
yielding 63% of product 10, Mp.: 295–297 °C.
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F. A. Bassyouni et al.
2-(Methoxy(phenyl)methylsulfonyl)-1-methyl-1H-perimidine (5)
1H-NMR (500 MHz, DMSO): d = 3.20 (3H, s, N-CH3), 3.40 (3H, s, OCH3), 5.60
(IH, d, CH), 6.80–7.00 (5H, m, Ar–H), 7.22–7.65 (6H, m, Ar–H). IR (KBr) cm-1
:
v = 1,647 (C=N), 1,320 (SO2). MS: m/z = 367 [M? ?1, 18%]. Anal. Calcd. for
C20H18N2O3S C, 65.55; H, 4.95; N, 7.64; S, 8.75. Found: C, 65.50; H, 4.89; N, 7.60;
S, 8.68.
2-((Methoxy(phenyl)methylsulfonyl)methyl)-1-methyl-1H-perimidine (10)
1H-NMR (500 MHz, DMSO): d = 3.20 (3H, s, N-CH3), 3.40 (3H, s, OCH3), 3.65
(1H, s, CH2S), 5.70 (2H, d, CH), 6.80–7.00 (5H, m, Ar–H), 7.20–7.65 (6H, m, Ar–
H). IR (KBr) cm-1 : v = 1,645 (C=N), 1,340 (SO2). MS: m/z = 380 [M?, 60%].
Anal. Calcd. For C21H20N2O3S: C, 66.29; H, 5.30; N, 7.36; S, 8.43. Found: C,
66.24; H, 5.35; N, 7.30; S,8.47.
Synthesis of 1,2-bis(2-substituted-1H-perimidin-1-yl)ethane-1,2-dione (11)
and (12)
To a solution of compound 1 or 6 (0.033 mol) in MeOH (100 mL) was added diethyl
oxalate (2.26 g, 0.016 mol) in a 2:1 molar ratio. The solution was refluxed for 2 h, and
then conc. HCl (6 mL) was added dropwise with constant stirring. The product which
formed was filtered off under vacuum, washed thoroughly with water, and then n-
hexane and dried under vacuum and crystalline from ethyl acetate yielding 75% of
product 11. Mp.: 275–277 °C and 72% yielding of product 12. Mp.: 282–284 °C.
1,2-Bis(2-mercapto-1H-perimidin-1-yl)ethane-1,2-dione (11)
1H-NMR (500 MHz, DMSO): d = 3.90 (2H, ss, 2 SH), 6.90–7.65 (12H, m, Ar–H).
IR (KBr) cm-1: v = 1, 720, 1,740 (C=O), 1,647–1,660 (C=N), 2,550 (SH). MS: m/
z = 453 [M? -1, 35%]. Anal. Calcd. for C24H14N4O2S2: C, 63.42; H, 3.10; N,
12.33; S, 14.11. Found: C, 63.49; H, 3.13; N, 12.35; S, 14.06.
1,2-Bis(2-mercaptomethyl-1H-perimidin-1-yl)ethane-1,2-dione (12)
1H-NMR (500 MHz, DMSO): d = 3.58 (2H, ss, 2CH2-SH), 3.80–3.90 (4H, ss, 2
CH2S), 6.90–7.60 (12H, m, Ar–H). IR (KBr) cm-1: v = 1,745, 1,720 (C=O);
1,640–1,660 (C=N); 2,600 (SH). MS: m/z = 480 [M? -2, 15%]. Anal. Calcd. for
C26H18N4O2S2: C, 64.71; H, 3.76; N, 11.61; S, 13.29. Found: C, 64.75; H, 3.73; N,
11.65; S, 13.26.
Reaction of compounds 11 and 12 with diamino compounds: General procedure
for preparation of compounds (13–15)
A mixture of compound 11 or 12 (10 mmol) and the appropriate diamino
derivatives, namely O-phenylenediamine, 3,4 diaminobenzoic acid and 2,3
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Synthesis of new transition metal complexes
1533
diaminopyridine (10 mmol), in absolute ethanol (25 mL), and TEA (1 mL), were
refluxed with stirring for 6–8 h. The solid product formed was filtered off, washed
with water, and recrystallized from ethyl acetate to afford the compounds 13–15 in
70–75% yield.
1,10-(Quinoxaline-2,3-diyl)bis(1H-perimidine-2-thiol) (13)
1
72% yield. Mp. [300 °C. H-NMR (500 MHz, DMSO): d = 3.80 (2H, ss, 2SH),
6.90–7.60 (12H, m, Ar–H), 7.70–7.90 (4H, m, Ar–H). IR (KBr) cm-1
:
v = 1,620–1,640 (C=N). MS: m/z = 526 [M?, 25%]. Anal. Calcd. for
C30H18N6S2: C, 68.42; H, 3.45; N, 15.96; S, 12.18. Found: C, 68.45; H, 3.43; N,
15.94; S, 12.16.
2,3-Bis(2-mercapto-1H-perimidin-1-yl)quinoxaline-6-carboxylic acid (14a)
1
70% yield. Mp. [300 °C. H-NMR (500 MHz, DMSO): d = 3.75 (2H, ss, 2 SH),
6.90–7.70 (12H, m, Ar–H), 7.88–8.00 (3H, m, Ar–H), 12.10 (1H, s, OH); IR (KBr)
cm-1: v = 3,390 (OH), 1,620–1,640 (C=N). MS: m/z = 570 [M?, 20%]. Anal.
Calcd. for C31H18N6O2S2: C, 65.25; H, 3.18; N, 14.73; S, 11.24. Found: C, 65.30;
H, 3.13; N, 14.75; S, 11.26.
2,3-Bis(2-(mercaptomethyl)-1H-perimidin-1-yl)quinoxaline-6-carboxylic acid (14b)
75% yield, Mp. [300 °C. 1H-NMR (500 MHz, DMSO): d = 3.58 (2H, ss,
2CH2SH), 3.85–3.95 (4H, ss, 2CH2-S), 6.90–7.70 (12H, m, Ar–H),7.80–7.95 (3H,
m, Ar–H),12.40 (1H, s, OH); IR (KBr) cm-1: v = 3,395 (OH), 1,620–1,640 (C=N).
MS: m/z = 598 [M?, 24%]. Anal. Calcd. for C33H22N6O2S2: C, 66.20; H, 3.70; N,
14.04; S, 10.71. Found: C, 66.25; H, 3.73; N, 14.08; S, 10.76.
(1,10-(Pyrido[2,3-b]pyrazine-2,3-diyl)bis(1H-perimidine-2,1-diyl))dimethanethiol
(15)
1
75% yield. Mp. [300 °C. H-NMR (500 MHz, DMSO): d = 3.58 (2H, ss, CH2
SH), 3.90 (4H, ss, 2CH2-S), 6.80–7.60 (12H, m, Ar–H), 7.80–7.95 (3H, m, Ar–H).
IR (KBr) cm-1: v = 1,620–1,645 (C=N). MS: m/z = 556 [M? ?1, 15%]. Anal.
Calcd. for C31H21N7S2: C, 67.01; H, 3.81; N, 17.64; S, 11.54. Found: C, 67.05; H,
3.83; N, 17.68; S, 11.56.
Synthesis of the transition metal complexes [Cu(en)2](Ac)2; [Co(en)2]Cl2;
[Ag(en)]NO3 and [Ru(en)2]Cl3
[Cu(en)2-H2L1](Ac)2ꢀ2H2O complexe (16)
To a stirred solution of ligand H2L1 (0.24 g, 0.5 mmol) in 50 mL ethanol, warmed
for 15 min, was added an aqueous solution of [Cu (en)2](Ac)2 (0.16 g, 0.5 mmol in
15 mL hot ethyl alcohol) dropwise over 30 min at 50 °C; molar ratio
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F. A. Bassyouni et al.
metal:en:ligand 1:2:1. The mixture was refluxed at these conditions for 24 h. The
resulting brown precipitate was filtered off, washed several times with small portions
of hot ethanol, diethyl ether, and dried in vacuum desiccator over anhydrous calcium
chloride, as a deep brown color. Yield 70%, 0.28 g pure. Mp. [300.
IR (KBr) cm-1: v = 3,385 (OH) H2O, 3,234, 3,140 (NH2), 2,924,1,535, 631
(CH2), 2,490 (SH), 1,669, 1,639 (C=N), 395 (Cu–N). Anal. Calcd for
C32H36N8S2O6Cu (755.54): Calcd : C, 50.82; H, 4.76; N, 14.82; S, 8.47. Found:
C, 50.60; H, 4.32; N, 14.80; S, 8.45%. Molar conductance Km (X-1cm2mol-1): 68
(electrolytic nature). Magnetic moment: 1.73 B.M (square planar geometry).
[Co(en)2-H2L1(H2O)2]Cl2ꢀ3H2O complex (17)
A similar procedure was carried out for Co (II) complex as well as procedure 17,
molar ratio metal:en:ligand 1:2:1, as deep brown color. Yield 79.69%, 0.56 g pure,
Mp.: [300. IR (KBr) cm-1
: v = 3,412 (OH)H2O, 3,205, 3,181 (NH2),
2,975,1,562d, 653r (CH2), 2,417 (SH), 1,630, 1,600 (C=N), 365 (Co–N). Anal
Calcd. for C28H32N8S2O5Cl2Co (753.93): Calc.: C, 44.56; H, 4.24; N, 14.85; S,
8.48. Found; C, 44.36; H, 3.92; N, 14.58; S, 8.25%. Molar conductance Km
(X-1cm2mol-1): 73 (electrolytic nature). Magnetic moment: 4.55 B.M (confirmed
octahedral geometry).
[Ag(en)-H2L1]NO3ꢀ2H2O complex (18)
The same procedure was carried out for Ag (I) H2L1 complex as 17 and 18, molar
ratio metal:en:ligand 1:2:1, as deep brown color. Yield 76.01%, 0.28 g pure.
Mp. [300. 1H-1H NMR: d NH2 at 5.2 ppm, d SH at 3.75 ppm, d CH2 at
3.80–3.94 ppm, and d of the aromatic part at 6.90–7.90 ppm. IR (KBr) cm-1
:
v = 3,320 (OH)H2O, 3268 (NH2), 2,966, 1,537d, 709 (CH2), 2,486 (SH), 1,614
(C=N), 360 (Ag–N). Anal. Calcd. for C28H30N8S2O3Ag (641.87): Calc.: C, 52.35;
H, 4.67; N, 8.72; S, 9.97. Found: C, 52.10; H, 4.41; N, 8.59; S, 9.83%. Molar
conductance Km (X-1cm2mol-1): 63 (electrolytic nature).
[Cu(en)2-H2L2](Ac)2ꢀ3H2O complex (19)
A similar procedure for 17–19 was carried out using ligand H2L2 for Cu (II)
complex, molar ratio metal:en:ligand 1:2:1, deep brown color. Yield 80.24%, 0.26 g
pure, Mp.: [300. IR (KBr) cm-1 : v = 3,383 (OH) H2O, 3,221, 3,133 (NH2), 2,920,
1,537, 618 (CH2), 2,450 (SH), 1,610, 1,583 (C=N), 681 (Cu–N). Anal. Calcd. for
C34H42N8S2O7Cu (801.54): Calcd : C, 50.90; H, 5.23; N, 13.97; S, 7.98. Found: C,
50.65; H, 5.10; N, 13.78; S, 7.67%. Molar conductance Km (X-1cm2mol-1): 69
(electrolytic nature). Magnetic moment: 1.71 B.M (square planar geometry).
[Ru(en)2-H2L2 Cl2]Clꢀ3H2O complexe (20)
A final procedure was carried out using the ligand H2L2 as Ru-H2L2 complex as
well as 19, molar ratio metal: en: ligand 1:2:1, deep brown color. Yield 75.61%,
123

Synthesis of new transition metal complexes
1535
0.40 g pure, Mp.: [300. IR (KBr) cm-1 : v = 3,427(OH)H2O, 3,198, 3,117 (NH2),
2,927,1,477d, 671 (CH2), 2,445 (SH), 1,629, 1,579 (C=N), 460 (Ru–N), 380 (Ru-
Cl). Anal. Calcd. for C30H34N8S2O4Cl3Ru (841.50): Calc.: C, 42.78; H, 4.04; N,
13.30; S, 7.60. Found: C, 42.53; H, 3.99; N, 13.15; S, 7.50%. Molar conductance Km
(X-1cm2mol-1): 75 (electrolytic nature). Magnetic moment: 1.73 B.M (confirmed
octahedral geometry).
Results and discussion
Reaction of naphthalene-1,8-diamine, potassium hydroxide and carbon disulphide in
ethanol under reflux for 6 h afforded the starting compound 1H-perimidine-2-thiol
(1) in 68% yield which was further reacted with benzoyl chloride in the presence of
potassium carbonate and acetone to gave 1H-perimidine-2-yl-benzothionate (2).
The latter compound was easily converted to (1H-perimidine-2-ylthio) (phenyl)
methanol (3) by reduction with sodium borohydride. Compound 3 was oxidized
yielding the corresponding compound (1H-perimidine-2-ylsulfonyl) (phenyl)
methanol (4). Compound 4 which was methylated with methyl iodide in the
presence of potassium carbonate led to the formation of 2-(methoxy(phenyl)meth-
ylsulfonyl)-1-methyl-1H-perimidine (5) (Scheme 1). The structure of compounds 1,
2, 3, 4, and 5 were established on the basis of their elemental analysis and spectral
data. For example, 1H NMR spectrum of compound 3 indicated the presence of the
(CH) singlet at 5.70 ppm as well as the presence of two singlets at 11.20 and
12.90 ppm, corresponding to NH and OH in addition to IR spectrum showed the
1
presence of two bands at 3,290 and 3,396 cm-1 for the NH and OH groups. H-
NMR spectrum of the compound 4 gave the evidence of the presence of aromatic
protons as a multiple at d 6.85–7.65 ppm, and mass spectrum of compound 4
showed a molecular ion peak at m/z at 338 (Cf. experimental part). The IR spectrum
of compound 5 showed disappeared of NH and OH characteristic bands.
In a similar manner, (1H-perimidine-2-yl) methanethiol (6) was prepared upon
the condensation reaction of naphthalene-1,8-diamine with thioglycolic acid in the
presence of 4NHCl. Compound 6 was reacted with benzoyl chloride in the presence
of potassium carbonate and acetone to afford (1H-perimidin-2-yl) methyl)benzo-
thionate (7) which was reduced with sodium borohydride to form the corresponding
[(1H-perimidin-2-yl) methylthio (phenyl)methanol (8), which was oxidized to gave
the corresponding ((1H-perimidin-2-yl) methylsulfonyl)(phenyl)methanol (9), and
subsequent methylatation was carried out with methyl iodide to produce the
corresponding 2-((methoxy(phenyl)methylsulfonyl)methyl)-1-methyl-1H-perimi-
dine (10) (Scheme 1). (All synthesized compounds are indicated by TLC).
In addition, compounds 6, 7, 8, 9 and 10 gave satisfactory elemental analyses and
spectroscopic data (IR, 1H NMR, MS) consistent with their assigned structures. The
IR spectra of compounds 9 and 10 showed characteristic absorption bands at 1,320
and 1,340 cm1 for the SO2 group, the OH group at 3,390 cm1 and the NH group at
3,280 cm1 for compound 9 and disappeared of NH and OH for compound 10,
respectively. The mass spectrum of the isolated product 10 showed a peak
corresponding to the molecular ion at m/z 380.
123

1536
F. A. Bassyouni et al.
NH
N
NH
N
SH
SH
PhCOCl
PhCOCl
Acetone/K2CO3
i
6
i
1
Acetone/K2CO 3
NH
N
O
NH
N
O
S
S
7
2
ii
NaBH4
ii NaBH4
NH
N
NH
OH
S
S
OH
N
8
3
iii
H2O2/AcOH
H2O2/AcOH
iii
O
S
O
O
O
N
N
OCH3
NH
S
OH
MeI
iv
NH
S
OH
O
MeI
iv
N
N
OCH3
O
N
S
O
CH3
N
O
CH3
10
9
4
5
Scheme 1 Conditions and reagents: (i) PhCOCl/acetone/K2CO3/reflux, (ii) NaBH4/chloroform/0 °C,
(iii) H2O2/AcOH/80 °C, (iv) Mel/acetone/K2CO3/reflux
Furthermore, treatment of 1H-perimidine derivatives 1 and 6 with dietyloxalate
in methanol and in the presence of HCl and refluxed in 2:1 molar ratio afforded only
one product in each case (as examined by TLC), identified as 1,2-bis(2-substituent -
1H-perimidin-1-yl)ethane-1,2-dione derivatives 11 and 12, respectively (Scheme 2).
The structures of the latter compounds were established on the basis of their
elemental analysis and spectral data. The IR spectra of the isolated products 11 or 12
revealed the appearance of carbonyl absorption bands at 1,720, 1,740 cm1 and SH at
2,550, and 2,600 cm1.
Reaction of 1,2-bis (2-substituted-1H-perimidin-1-yl)ethane-1,2-dione derivatives
11 and 12 with o-phenylenediamine, 3,4-diaminobenzoic acid and pyridine-2,3-
diamine in ethanol and in presence of TEA under refluxed condition afforded one
product in each time (as evidenced by TLC) which was identified as 1,10-(quinoxaline-
2,3-diyl)bis(1H-perimidine-2-thiol)
(13),
2,3-bis(2-mercapto-1H-perimidin-1-
yl)quinoxaline-6-carboxylic acid (14a), 2,3-bis(2-(mercaptomethyl)-1H-perimidin-
1-yl)quinoxaline-6-carboxylic acid (14b) and (1,10-(pyrido[2,3-b]pyrazine-2,3-
diyl)bis(1H-perimidine-2,1-diyl))dimethanethiol (15), respectively (Scheme 2).
The IR spectra of compounds 13, 14a,b and 15 indicated the absence of C=O
groups and the presence of different bands at 1,620–1,645 cm-1 for C=N groups.
The structures of compounds 13, 14a,b and 15 were established on the basis of their
elemental analysis and spectral data. For example, the structure of compound 13 is
supported by its mass spectrum which showed a molecular ion peak at m/z 526. The
123

Synthesis of new transition metal complexes
1537
i
11, R= SH
12, R= CH2SH
1, R= SH
6, R= CH2SH
iii
R = CH2SH
R = SH
ii
iv
13
15
14 a, R = SH
14 b, R = CH2SH
Scheme 2 Reagents and conditions: (i) methanol/HCl/reflux, (ii–iv) ethanol/TEA/reflux
1H NMR spectrum of the compound 14b exhibits signals at 3.85–3.95 ppm due to
the presence of methylene protons and OH at 12.40 ppm, in addition to aromatic
protons as a multiple at 6.90–7.95 ppm, respectively. The IR spectrum of
compounds 14a,b showed characteristic absorption bands at 1,620–1,640 cm-1
due to the presence of C=N and OH group at 3,395 cm-1, and compound 15 showed
characteristic absorption bands at 1,620–1,645 cm-1 due to the presence of C=N
groups. All the synthesized compounds 13-15 were confirmed by thin layer
chromatography.
Synthesis and characterization of transition metal complexes
All the complexes are colored, non-hygroscopic and stable solids. They are
insoluble in water, sparingly soluble in the common organic solvents, but fairly
soluble in DMF. Physical properties of the complexes are given in Table 1. The
metal complexes 16–18 of compound 11 with [Cu(en)2](Ac)2, [Co(en)2]Cl2 and
[Ag(en)2] NO3 and the metal complexes 19 and 20 of compound 12 with
[Cu(en)2](Ac)2, and [Ru(en)2]Cl3, respectively, were synthesized according to the
´
reported methods by Merchan et al. [28] forming 1:1 (metal:ligand) complexes.
1
These complexes were characterized by elemental analyses, IR and H-NMR (for
123

1538
F. A. Bassyouni et al.
Ligand 1
,
H2LI
N
N
SH
C=O
C=O
N
N
[Cu(en)2](Ac)2
[Ag(en)2]NO3
iii
i
SH
11
N
N
N
SH
SH
N
CH -CH
2
CH -CH
2
2
2
C=N
C=N
C=N
C=N
NH
NH
2
2
Cu
Ag
(Ac) (H O)
2
2
2
No3 (H2O)2
NH
NH
2
2
CH -CH
2
2
CH -CH
2
2
N
N
N
N
ii
SH
SH
18
16
[Co (en)2 ] Cl2
N
N
SH
CH -CH
2
2
OH2
C=N
C=N
NH
2
Co
Cl (H O)
3
3
2
NH
2
OH2
CH -CH
2
2
N
N
SH
17
Scheme 3 Reagents and conditions : (i–iii) ethanol/reflux
diamagnetic complexes), electronic and mass spectra, magnetic moments and
conductance measurements as well as thermogravimetric analyses (TG). Based
upon this characterization, the prepared complexes have the proposed structural
formulae: [Cu(en)2-(H2L1)](Ac)2ꢀ2H2O (16), [Co(en)2-(H2L1)(H2O)2]Cl2ꢀ3H2O (17)
and [Ag(en)2-H2L1] NO3ꢀ2H2O (18) for ligand 11; H2L1, on the other hand, [Cu
(en)2-H2L2](Ac)2ꢀ3H2O (19), and [Ru(en)2-H2L2Cl2]Clꢀ4H2O (20) for ligand 12;
H2L2 (cf. Schemes 3, 4).
123

Synthesis of new transition metal complexes
1539
123

1540
F. A. Bassyouni et al.
,
H2L2
Ligand 2
SH
N
N
CH2
C=O
C=O
N
N
[Ru(en)2]Cl3
ii
[Cu(en)2](Ac)2
i
CH2
SH
12
SH
N
N
N
N
SH
CH -CH
2
CH -CH
2
2
2
Cl
C=N
C=N
C=N
C=N
NH
NH
NH
NH
2
2
Cu
Ru
Cl
.H O
Cl
.(H O)
3
(Ac)
2
2
2
2
2
CH -CH
2
2
CH -CH
2
2
N
N
N
N
SH
SH
19
20
Scheme 4 Reagents and conditions: (i–ii) ethanol/reflux
Molar conductance studies
The metal complexes were dissolved in DMF and the molar conductivities of their
solutions (10-3 M) at room temperature were measured to establish the charge of
the metal complexes. The elemental analyses and the conductance data are reported
in Table 1, indicated that all the metal complexes have conductivity values in the
range 68–75 Km (X-1cm2mol-1) suggesting the electrolytic nature of these
complexes.
Infrared spectral analysis of ligands and metal complexes
The infrared spectral bands of the ligands and their metal complexes are listed in
Table 2. For the Cu (II), Co (II)-H2L1 and Ru (III)-H2L2complexes, the
characteristic bands at 1,740, 1,720 cm-1 attributed to m(C=O) disappears, with
the formation of a new strong band at 1,579–1,669 cm-1 region which indicates the
condensation of m (C=O) group with NH2 group of bis-(ethylenediamine) metal
complexes. The formation of the m (C=N) band, and the disappearance of the m
(C=O) band in the complexes commensurate with effective Schiff’s base
condensation. The alkyl CH2 group shows characteristic stretching absorption
bands in the region 2,920–2,975, deformation band at 1,477–1,537 and rocking
modes at 618–709 cm-1
,
respectively.
A
medium intensity band at
123

Synthesis of new transition metal complexes
1541
Table 2 Infrared spectral data for H2L1, H2L2 and their metal complexes of compounds 16–20
Compound
m(H2O) m(NH2)
m(CH2)
m(SH) m(C=O)
m(C=N)
m(M–
N)
H2L1
–
–
–
2,550 1,720,
1,740
1,647,
1,660
–
C24H14N4S2O2
[Cu(en)2-H2L1](Ac)2ꢀ2H2O
3,285
3,234,
3,140
2,924,
1,535
2,490
2,417
2,486
–
–
–
1,669,
1,639
424
C32H36N8S2O6Cu
r-631
[Co(en)2H2L1(H2O)2]
3,412
3,320
3,205,
3,181
2,975,
1,562
1,630,
1,600
365
360
Cl2ꢀ3H2O
28H32N8S2O5Cl2Cu
C
r-653
[Ag(en)2-H2L1] NO3ꢀ2H2O
C28H30N8S2O3Ag
3,268
–
2,924,
1,537
1,614
r-709
2,920
H2L2
–
2,600 1,720,
1,740
1,645,
1,660
–
C26H18N4S2O2
[Cu(en)2-H2L2](Ac)2ꢀ3H2O
3,383
3,221,
3,133
2,920,
1,537
2,450
–
1,610,
1,583
420
C
34H42N8S2O7Cu
r-618
[Ru(en)2-H2L2(Cl)2]Clꢀ4H2O 3,427
3,198,
3,117
2,927,
1,477
2,445
–
1,629,
1,579
460
C
30H34N8S2O4Cl3Ru
r-671
3,317–3,234 cm-1 was observed in the complexes which was assigned to m (NH2)
groups of the other side of bis(ethylenediamine) moiety suggesting 1:1 condensation
reaction. In the IR region, the bands appearing at ranges 360–460 cm-1 have been
assigned to m (M–N), which further confirms the formation of the complexes. The m
(Ru-Cl) stretching vibration appears as a strong band at 335 cm-1
.
1H NMR analysis of complex [Ag(en)2-H2L1] NO3ꢀ2H2O
The 1H NMR spectra of the diamagnetic complex [Ag(en)2-H2L1] NO3ꢀ2H2O
exhibited the presence of only a slight shift of d NH2 at 5.2 ppm compared to free
ligand (at 5.95 ppm) in this complex, and displays signals d SH at 3.80 ppm, d CH2
at 3.70–3.84 ppm, and d of the aromatic part at 6.75–7.60 ppm.
Electronic spectra
Electronic absorption spectral bands and magnetic moment of the ligands and their
complexes are listed in Table 3.
For Cu(II)-H2L1 and Cu(II)-H2L2 complexes, the magnetic moment values 1.73
and 1.71, respectively, are attributed to one unpaired electron which gave a broad
2
2
band at 690 and 678 nm assignable to B1g ? A1g transition which is
123

1542
F. A. Bassyouni et al.
Table 3 Electronic absorption spectral bands of the ligand H2L1,H2L2 and their complexes as well as
their magnetic moments of compounds 16–20
Compound
Electronic absorption bands kmax. (nm) in DMSO
leff
Intraligand and charge transfer bands (nm) d–d transitions (B.M.)
H2L1
211, 220, 234, 281, 321, 340, 354
217, 235, 290, 328, 349, 350
–
–
C24H14N4S2O2
[Cu(en)2-H2L1](Ac)2ꢀ2H2O
690
1.73
4.55
–
C32H36N8S2O6Cu
[Co(en)2H2L1(H2O)2] Cl2ꢀ3H2O 204, 207, 234, 281, 321, 339, 350
460, 560
C28H32N8S2O5Cl2Cu
[Ag(en)2-H2L1] NO3ꢀ2H2O
281, 321, 330
–
C28H30N8S2O3Ag
H2L2
207, 225, 237, 316, 330
221, 229, 238, 296, 328, 342, 355
207, 274, 321, 405
–
–
C26H18N4S2O2
[Cu(en)2-H2L2](Ac)2ꢀ3H2O
678
1.71
1.73
C34H42N8S2O7Cu
[Ru(en)2-H2L2 (Cl)2] Clꢀ4H2O
550, 720
C30H34N8S2O4Cl3Ru
characteristic of square planar environment around the copper (II) ion. A strong
metal ligand charge transfer (MLCT) bands at the 211–351 nm region appear in all
the complexes attributed to the p–p* transition [29].
The complex [Co(en)2-H2L1(H2O)2]Cl2ꢀ3H2O exhibited new bands around
560 nm and a strong high-energy band at 460 nm, which were assigned to the
4
4
4
4
transitions T1g(F) ? T2g(F), T1g(F) ? T1g(P), respectively, for a high-spin
octahedral geometry. The magnetic susceptibility measurements (4.55 B.M.) for the
solid Co (II) complexes are also indicative of three unpaired electrons per Co (II)
ion consistent with their octahedral environment.
In case of the [Ru(en)2-H2L2 Cl2]Clꢀ4H2O complex, the electronic spectra
showed many types of transitions, the first one appeared at range 207–274 nm
which can be assigned to p–p* transition. The second type of transitions appeared at
range 321 nm which can be assigned to n - p* transition was due to transitions
involving molecular orbital of the C=N chromospheres and the benzene ring. These
bands have also been shifted upon complexation indicating that the imine group
nitrogen atom appears to be coordinated to the metal ion. The spectra of the
complexes show another types of transitions different from the free ligands. The first
one was at range 405 nm which can be assigned to ligand to metal charge transfer
[29]. The other one appeared at 550, 720 nm which can be attributed to d–
d transitions in the metal orbital [30]. The diamagnetic complex of [Ag (en)2-H2L1]
NO3ꢀ2H2O showed strong bands at 280, 321, and 330 nm, indicating a tetrahedral
geometry of these complexes.
123

Synthesis of new transition metal complexes
1543
123

1544
F. A. Bassyouni et al.
Thermal analysis
Thermo gravimetric analysis (TGA) results of the investigated metal complexes are
reported in Table 4.
Thermo gravimetric analyses (TGA) of Cu(en)2-H2L1](Ac)2ꢀ2H2O and [Cu(en)2-
H2L2](Ac)2ꢀ3H2O complex shows that the first weight loss of 4.38 (cal. 4.76) and
7.33 (cal 0.6.73) % from 50 to 150 and 90 to 120 °C, corresponds to the loss of two
and three hydrated water molecules, respectively. Increasing temperature led to the
further decomposition at range 200–740 °C, as indicated by a significant weight loss
with CuO of 10.58 (cal.10.52) and 9.68 (cal.9.92) % at 650 and 740 °C, respectively
[32].
Another example for [Ru (en)2-H2L2(Cl2)]Clꢀ4H2O: the thermal decomposition
occurs at three steps. The first degradation step take place in range of 90–100 °C
and its corresponds to elimination of four water molecules due to a weight loss of
8.63% in a good matching with theoretical value 8.55%. The second step falls in the
range 100–500 °C, which is assigned to loss of the organic part (C30H34N8S2O3). At
the third step, the RuOCl is the final product remaining stable until 800 °C [33]. The
decomposition steps of all complexes can be represented as:
50ꢁ150ꢂC
200ꢁ2470 ꢂC
Â
Ã
Â
Ã
CuðenÞ ꢁH L1 ðAcÞ ꢀ 2H O
CuðenÞ2ꢁH2L ðAcÞ2
ƒƒƒƒ!
ƒƒƒƒ!
2
2
2
2
250ꢁ400 ꢂC
400ꢁ650
ꢂC
Â
Ã
unstable intermediate
Â
CuꢁH2L1
CuO:
Ã
ƒƒƒƒƒƒ!
ƒƒƒƒƒ!
90ꢁ120 ꢂC
Ã
unstable intermediate
Â
CuðenÞ ꢁH L2 ðAcÞ ꢀ3H O
CuðenÞ2ꢁH2L2 ðAcÞ2
ƒƒƒƒƒ!
2
2
2
2
250ꢁ495 ꢂC
495ꢁ730 ꢂC
120ꢁ250 ꢂC
740 ꢂC
Â
Ã
CuꢁH2L2
ƒƒƒƒƒ!
ƒƒƒƒƒ!
ƒƒƒƒƒ!
CuO
90ꢁ150 ꢂC
Â
Ã
Â
Ã
CoðenÞ ꢁH L1ðH OÞ Cl :3H O
CoðenÞ2ꢁH2L1ðH2OÞ2 Cl2
ƒƒƒƒƒ!
2
2
2
2
2
2
190ꢁ220 ꢂC
220ꢁ477 ꢂC
Â
Ã
CoðenÞ ꢁH2L1 Cl2
unstable intermediate
ƒƒƒƒƒ!
ƒƒƒƒƒ!
2
477ꢁ780 ꢂC
CO O4 :
3
ƒƒƒƒƒ!
ꢂC
Â
Ã
Â
Ã
AgðenÞ ꢁH2L1 NO ꢀH O 80ꢁ104 AgðenÞ ꢁH2L1 NO3
ƒƒƒƒƒ!
3
2
2
2
170ꢁ206 ꢂC
220ꢁ450 ꢂC
½AgðenÞꢁH L1ꢃ
unstable intermediate
ƒƒƒƒƒ!
ƒƒƒƒƒ!
2
450ꢁ650 ꢂC
Ag O
2
ƒƒƒƒƒ!
100 ꢂC
100ꢁ500 ꢂC
Â
Ã
Â
Ã
RuðenÞ ꢁH L2ðCl Þ Clꢀ4H O
RuðenÞ ꢁH L2ðCl Þ Cl
unstable
ƒƒ!
ƒƒƒƒƒ!
2
2
2
2
2
2
2
500ꢁ800 ꢂC
intermediate ðLoss organic partÞ
RuOCl
ƒƒƒƒƒ!
123

Synthesis of new transition metal complexes
1545
Pharmacological screening
Anti-inflammatory activity
Animals
Adult male albino rats of 120–150 g body weight were obtained from the animal
house of National Research Centre, Cairo Egypt. Animals were kept in separate
cages, six animals each, under hygienic conditions in temperature-controlled rooms
at 25 °C. Animals were allowed free access to standard laboratory diet and water,
and they were maintained at a 12 h light/dark cycle. Work was done according to
internationally accepted principles for laboratory animal’s use and care in European
Community Guidelines [34], and Ethical Committee of National Research Centre
Approval was obtained.
Drugs
Indomethacin (Nile Company, Egypt), Carrageenan (Sigma, USA), Acetyl Salicylic
acid (CID) and normal saline were obtained from the local market. All tested
compounds and reference drugs were given to the animals in oral dose of 50 mg/kg-1
b.w. in DMSO while the negative control group received 1 mL of DMSO.
Anti-inflammatory assay
The anti-inflammatory activity of the newly synthesized compounds 2, 3, 7, 8, 12, 13,
17, 18, 19 and 20 were investigated in comparison with Indomethacin according to
paw edema method [35]. The animals were randomly divided into groups of six
animals each and were fasted for 18 h before the experiment, with free access to water.
Standard drug indomethacin was administered orally at 20 mg/kg-1. Carrageenan
solution in saline (1%, 0.1 mL) was injected into sub-planter region of right hind paw
of each rat; the left hind paw volume was injected with 0.1 mL saline; 1 h later the left
hind paw volume was measured using Plethysmometer. The percent edema inhibition
was calculated from the mean difference between the two paws using a Plethysmom-
eter (7141: UGO Basile, Comerio, Italy). Each value represents the mean SEM
relative to the standard. The mean increase of paw volume at each time interval was
compared with that of control group (six rats treated with carrageenan, but without test
compounds) at the same time intervals as shown in Table 5. The percentage inhibition
values were calculated according to the formula: % Anti-inflammatory activ-
ity = (1 - Rt/Rc) 9 100 (Rt = result of tested group; Rc = result of control group).
Analgesic assay
Analgesic activity was evaluated using method described by Eddy and Leibach [36]
using a hot plate method at 53 0.5 °C. Albino mice allocated to different groups
consisting of six animals each. Analgesic activity was measured at 60 and 90 min
after drug administration at 50 mg/kg-1 and the reference drug acetyl salicylic acid
123

1546
F. A. Bassyouni et al.
Table 5 Acute anti-inflammatory effect (Carrageenan-induced paw edema) of compounds 2, 3, 7, 8, 12,
13, 17, 18, 19 and 20
Compounds
Oedema volume (% change from baseline)
1 h
2 h
3 h
4 h
Control
51.31 4.17
39.24 9.46
47.47 6.59
38.91 4.77
46.81 6.93
56.95 4.57
45.30 4.20
53.30 6.02
55.87 4.17
61.09 6.09
56.47 3.84
58.69 4.79
66.62 7.11
36.68 7.31*
56.66 7.25
48.90 5.93
55.15 4.85
68.19 5.89
52.72 8.32
58.03 8.10
49.95 4.47
72.28 4.44
51.91 3.02
60.95 12.30
70.74 7.24
39.73 7.83*
55.18 6.08
44.39 3.82
64.65 4.43
64.00 7.95
60.29 6.33
63.33 6.67
65.10 4.49
72.29 6.64
52.10 3.37*
64.01 7.88
67.45 5.59
24.92 6.13*
46.87 5.03*
36.04 3.36*
55.27 8.18*
68.90 5.83
46.61 6.30*
59.27 7.48
58.02 7.42
68.05 9.48
61.11 3.71
67.81 10.76
Indomethacin 20 mg/kg
2 (50 mg/kg)
3 (50 mg/kg)
7 (50 mg/kg)
8 (50 mg/kg)
12 (50 mg/kg)
13 (50 mg/kg)
17 (50 mg/kg)
18 (50 mg/kg)
19 (50 mg/kg)
20 (50 mg/kg)
* Significantly different from control at p \ 0.05
Table 6 Effect of drugs on the
Compounds
1 h
0
2 h
gastric ulcer number after drug
injection by 2 h
Control
0
0
0
Indomethacin
7.2 1.5
0.8 0.7
0.8 0.5
1.2 0.4
0.2 0.2
13.8 3.9*
1.0 0.8*
1.2 0.7*
1.3 0.5*
0.2 0.2*
2
3
7
8
12
13
17
18
19
0
0
0
0
0
0
0
0
0
0
0
0
0.8 0.8
0.2 0.1
0.3 0.3
1.0 1.0*
0.3 0.3*
0.5 0.5*
* Significantly different from
control at p \ 0.05
20
at 150 mg/kg-1, when each animal was placed gently on the hot plate at 53 °C. The
time in seconds at which the animal jumped or licked its legs was taken to be the
reaction time and compared to the negative control group and reference drug as
shown in Table 6.
Ulcerogenicity
Acute ulcerogenicity was determined according to the method of Corell et al. [37].
The animals were divided into groups as mentioned before. Ulcerogenic activity
was evaluated after oral administration of the tested compounds in 50 mg/kg-1 b.w.
123

Synthesis of new transition metal complexes
1547
and reference drug indomethacin 20 mg/kg-1 b.w. to the fasted animals, which
were then fed normal diet for 5 h and then sacrificed and their stomachs removed
and opened against grater curvature, washed with distilled water and cleaned gently
by normal saline. The mucosal damage was examined by means of a magnifying
lens. Mucosal damage was assessed using a scoring system. The mean score of each
treated group minus the mean score of the control group was regarded as the
severity index of gastric mucosal damage.
All experiments involving animals were carried out using protocols approved by
the Animal Committee, University of Barcelona (Spain). Animal care was in
compliance with Generalitat of Catalunya regulations on protection of animals used
for experimental and other scientific purposes.
Statistical analysis
Data are presented as mean SEM. Data were analyzed by ANOVA followed by
Duncan and multiple group comparison tests.
Rats were treated with test compounds (50 mg/kg) and their inflammatory
response to sub-planter injection of carrageenan was compared to untreated group
(n = 6). Indomethacin (10 mg/kg) was used as the reference anti-inflammatory
drug. Volumes of hind paws were measured using standard liquid displacement
technique. Percent change in paw volumes at 0, 1, 2, 3 and 4 h post-drug
administration were calculated and compared between different treatments. The
cumulative anti-inflammatory effect over the whole 4 h was represented by the
average change in paw volumes. Data are presented as mean SEM (Table 5).
Mice were treated with tested compounds (50 mg/kg) and their response to
thermal noxious stimulation was compared to untreated group (n = 6). Acetyl
Salicylic acid (20 mg/kg) was used as the reference central analgesic agent. Latent
time in seconds (withdrawal latency) required for the mice to lick a paw or jump
from the hot surface (52 0.1 °C) was measured and compared between different
treatment groups at 0, 60, and 90 min post-drug administration. Data are presented
as mean SEM.
The ulcerogenic activity of the tested compounds in comparison with
indomethacin clearly showed that compounds 12, 13 and 17 induced no ulcerogenic
effect. Meanwhile, compounds 18, 2, 3, 7, 8, 19 and 20 showed only slight
ulcerogenic effect. The mucous membrane of the stomach of the indomethacin-
treated rats showed severe signs of damage accompanied by perforations as shown
in Table 6. The finding correlates well and adds a very important advantage to their
anti-inflammatory activity. On the other hand, compounds 2, 3, 7 and 12 possesses
anti-inflammatory activity compared to the control group.
Antimicrobial activity
Antimicrobial assay
Antimicrobial activity of the synthesized compounds (2, 3, 8, 13, 14a, b, 16, 17, 18,
19 and 20) were screened in vitro and in comparison with control drugs Rifampicin
123

1548
F. A. Bassyouni et al.
Table 7 Antimicrobial activity of compounds 2, 3, 8, 13, 14a, 14b, 16, 17, 18, 19 and 20
Compounds
Inhibition zone (mm)
E. coli
S. aureus
B. subtilis
C. albicans
A. niger
2
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
3
-
-
????
-
-
8
???
????
-
-
???
???
??
??
??
-
13
??
-
??
??
-
14a
14b
??
??
??
-
-
16
-
-
17
-
-
18
-
-
-
19
??
-
??
??
??
-
-
20
-
-
Rifampicin
????
???
????
Inhibition zone diameter (% inhibition): ? 6–9 mm (33–50%); ?? 10–12 mm (55–67%); ???
13–15 mm (72–83%); ???? 16–18 mm (89–100%). Percentage inhibition values were relative to
inhibition zone (18 mm) with 100% inhibition
(Egyptian Pharmaceutical Trading, Cairo, Egypt) and evaluated against Gram-
positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and
fungi (Candida albicans and Aspergillus niger) by the agar diffusion technique [38,
39]. All microorganisms used were obtained from the culture collection of the
Department of Chemistry of Natural and Microbial Products, National Research
Center, Cairo, Egypt. The microorganisms were passaged at least twice to ensure
purity and viability. The compounds were mounted at a concentration of 100 lg/
disc. The bacteria were maintained on nutrient agar medium while yeast and fungi
were maintained on potato dextrose agar medium. DMSO was used as solvent
control which showed no inhibition zone. The agar media were incubated with the
different microorganism cultures tested. After 24 h of incubation at 30 °C for
bacteria and yeast and 72 h of incubation at 28 °C for fungi, the diameter in mm of
the inhibition zone was measured (Table 7). Rifampicin was used as a positive
control for antimicrobial activity at a concentration of 100 lg/disk. The results
shown in Table 7 revealed that compound 13 exhibited a wide range of
antimicrobial activity against Gram-positive and Gram-negative bacteria and yeast,
while compounds 8, 14a, b and 16 exhibited a moderate antimicrobial activity
against E. coli and C. albicans. Compounds 17, 19 and 20 also exhibited a moderate
antibacterial activity in comparison with Rifampicin. But compound 3 exhibited
high inhibitory effect against B. subtilis strain.
Preparation of the discs
Compounds 2, 3, 8, 13, 14a, b, 16, 17, 18, 19 and 20 together with the positive
control Rifampicin were mounted on a paper disc prepared from blotting paper
123

Synthesis of new transition metal complexes
1549
(5 mm diameter) with the help of a micropipette at a concentration of 100 lg/15lL
DMSO/disc. The discs were applied on the microorganism-grown agar plates.
Preparation of agar plates
Minimal agar was used for the growth of specific microbial species. The preparation
of agar plates for Bacillus subtilis, Staphylococcus aureus and Escherichia coli
(bacteria) utilized nutrient agar (2.30 g; obtained from Panreac Quimica, Spain)
suspended in freshly distilled water (100 mL), and potato dextrose agar medium
(3.9 g/100 mL; obtained from Merck) for Candida albicans and Aspergillus niger
(fungi). This was allowed to soak for 15 min and then boiled in a water bath until
the agar was completely dissolved. The mixture was autoclaved for 15 min at 120
°C and then poured into previously sterilized Petri dishes and stored at 30 °C for
inoculation.
Procedure of inoculation
The spore suspension was prepared with the help of a platinum wire loop to reach a
microbial concentration equivalent of 0.5 Mac-Farland.
Application of the discs
Sterilized forceps were used for the application of the paper disc on previously
inoculated agar plates. When the discs were applied, they were incubated at 37 °C
for 24 h for bacteria and yeast, and at 28 °C for 48 h for fungi. The zone of
inhibition around the disc was then measured in millimeters.
Acknowledgment The authors acknowledge the financial support received from the National Research
Center, Cairo, Egypt (Project No: 8040204).
References
1. J.L. Di Martino-, J. Jacquault, J.P. Bazureau, J. Bull. Soc. Chim. F. 133, 587 (1996)
2. W.L. Deady, T. Rodemann, J. Heterocycl. Chem. 35, 1417 (1998)
3. N. Foroughifar, A. Mobinikhaled, H. Fathinejad Jirandehi, Sulfur Silicon Relat. Elem. 178, 1241
(2003)
4. F. Langa, P. de la Cruz, A. de la Hoz, A. Diaz-Ortiz, E. Diez-Barra, Contemp. Org. Synth. 4, 373
(1997)
5. N. Foroughifar, A. Mobinikhaledi, H. Jirandehi, S. Mem, Sulfur Silicon Relat. Elem. 178, 1269
(2003)
6. N. Foroughifar, A. Mobinnikhaledi, Asian J. Chem. 14, 61 (2002)
7. X. Bu, W.L. Deady, J.G. Finlay, C.B. Baguley, A.W. Denny, J. Med. Chem. 44, 2004 (2004)
8. F.A. Pozharskii, V.V. Dalnikovskaya, Russ. Chem. Rev. 50, 816 (1981)
9. M.N. Starshikoy, T.F. Pozharskii, Chem. Heterocycl. Compd. 9, 922 (1975)
10. I. Yavari, M. Adib, F. Jahani-moghaddam, R.H. Bijanzadeh, Tetrahedron 58, 6901 (2002)
11. J.J. Vanden Eynde, F. Delfosse, A. Mayence, V.Y. Haverbeke, Tetrahedron 51, 5813 (1995)
12. T.U. Mueller-Westerhoff, S. Vance, I.D. Yoon, Tetrahedron 47, 909 (1991)
13. M.J. Herbert, D.P. Woodgate, A.W. Denny, J. Med. Chem. 30, 2081 (1987)
14. J.W.K. Baker, R.A. March, S. Parsons, M.R. Paton, W.G. Stewart, Tetrahedron 58, 8505 (2002)
123

1550
F. A. Bassyouni et al.
15. J.J. Baldwin, L.E. Engelhardt, R. Hirschmann, F.G. Lundell, S.G. Ponticello, T.C. Ludden, S.C.
Sweet, A. Scriabine, N.N. Share, R. Hall, J. Med. Chem. 22, 687 (1979)
ˇ
16. D. Ivica, R. Mirta, V. Visnja, P.K. Sandra, K. Marijeta, P. Ivo, C. Marina, Bioorganic Med. Chem.
16, 5189 (2008)
17. B.Y. Rokade, Z.R. Sayyed, Rasayan J. Chem. 2, 972 (2009)
18. R. Stefano, M. Debrap, P.V. Peter, N.A. Edith, S.K. Shyam, W. Kevinj, O.S. Marcia, P.T. Albert, J.C.
James, H.S. Martin, Antimicrob. Agents Chemother. 40, 234 (1996)
´
19. M. Belen Tarallo, J.A. Costa-Filho, V.D. Ernanni, M. Antonio, Q. Clarice, P.R.F. Leite, B. Graciela,
´
G. Dinorah, T.H. Marıa, J. Argent. Chem. Soc. 97, 80 (2009)
20. M. Karuna, F. Nighat, S. Ran Vir, Indian J. Chem. 46A, 1221 (2007)
21. K. Irena, Recent Patents Anti Cancer Drug Discov. 1, 1 (2006)
22. R. Nairl, A. Shah, S. Baluja, S. Chanda, J. Serb. Chem. Soc. 71, 733 (2006)
23. K. Anil, K. Devinder, ARKIVOC. (xiv):117 (2007)
24. B.M. Vasudevachari, M.B.A. Antony, J. Biosci. 7, 33 (1985)
25. B.A. Fatma, B.A.M. Sherifa, O.I. Abdel Salam, M. Abdel Rehim, Egypt Pharm. J. 8, 107 (2009)
26. S.R. Eslam, B.A. Fatma, B.A.M. Sherifa, R.M. Hanaa, A.M. Mohamed, Acta Pharm. 60, 55 (2010)
27. T.A. Hanaa, B.A. Fatma, G.M. Amira, A.A. Mona, E.S. Wageeh, Pharmacol. Rep. 61, 1153 (2009)
28. L.E. Merchan, J. Garın, E. Melendez, D. Ortiz, T. Tejero, T Synthesis, 368 (1987)
29. B. Falguni, D.K. Anjan, M. Golam, P. Shie-Ming, B. Samaresh, Polyhedron 19, 1663 (2000)
30. F. Arjmand, B. Mohani, S. Ahmed, Eur. J. Med. Chem. 40, 1103 (2005)
31. N.S. Youssef, K.H. Hegab, Synth. React. Inorg. Met. Org. Chem. 35, 391 (2005)
32. H.R. Holm, A.F. Cotton, J. Am. Chem. Soc. 80, 5658 (1958)
33. S. Sharma, F. Athar, R.M. Maurya, A. Azam, Eur. J. Med. Chem. 40, 1414 (2005)
34. B. Tan, Guidelines on the care and use of animals for scientific purposes, national advisory com-
mittee for laboratory animal, Singapore (2004)
35. A. CWinter, A.E. Risley, W.G. Nus, Proc. Soc. Exp. Biol. Med. 111, 544 (1962)
36. B.N. Eddy, D. Leibach, J. Pharmacol. Exp. Ther. 107, 385 (1953)
37. T. Corell, K.J. Moller, J. Spawinski, Acta. Pharmacol. Toxicol. 45, 232 (1979)
38. J.K. Domig, S. Mayrhofer, U. Zitz, C. Mair, A. Petersson, E. Amtmann, K.H. Mayer, W. Kneifel, Int.
J. Food Microbiol. 120, 191 (2007)
39. O.E. Ajaiyeoba, A.P. Onocha, O.S. Nwozo, W. Sama, Fitoterapia. 74, 706 (2003)
123