JSCS Vol 64, No. 9
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J.
Serb. Chem. Soc. 64(9) 497-503 (1999)
UDC 547.94:542.611/Taxus baccata/:547.597
JSCS-2688
Original scientific paper
Semisynthesis of Taxol®:
an improved procedure for the isolation of 10-deacetylbaccatin III
R. N. SAICIC, R. MATOVIC and Z. CEKOVIC
Faculty of Chemistry, University of
Belgrade, Studentski trg 16, P.O.Box 158, YU-11001 Belgrade, and ICTM Center
for Chemistry, Njegoseva 12, Belgrade, Yugoslavia
(Received
17 February, revised 1 April 1999)
From
the needles of domestic yew, (Taxus baccata), 10-deacetylbaccatin III
(10-DAB) can be isolated in quantities of up to 297 mg per kg of fresh needles.
Additional quantities of 10-DAB can be obtained from the extract by NaBH4
mediated reductive hydrolysis of baccatin esters. A four-step procedure
converts 10-DAB into taxol in 58% overall yield.
Key
words: anti-tumor agents, taxol, natural products, semisynthesis.
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J.
Serb. Chem. Soc. 64(9) 505-512 (1999)
UDC 547.639-547.391.1:615.37
JSCS-2689
Original scientific paper
Substitued (E)-b-(benzoyl)acrylic
acids suppressed survival of neoplastic human HeLa cells
Z. JURANIC, LJ. STEVOVIC*, B. DRAKULIC**, T. STANOJKOVIC, S.
RADULOVIC and I. JURANIC
Institute for Oncology and
Radiology, Belgrade,
*Faculty of Chemistry, University of Belgrade, P.O.Box 158,
Belgrade and
**Center for Chemistry ICTM, Belgrade, Yugoslavia
(Received
27 January, revised 31 March 1999)
The
bacteriostatic activity of some of alkyl substituted (E)-b-(benzoyl)acrylic
acids was shown earlier. The aim of this study was to investigate the
antiproliferative action of 19 alkyl-, or halogeno-, or methoxy-, or acetamido-
substituted (E)-b-(benzoyl)acrylic acids, against human cervix
carcinoma, HeLa, cells. Target HeLa cells were continuously treated with
increasing concentrations of substituted (E)-b-(benzoyl)acrylic acids
during two days. The MTT test was used for assessment of the antiproliferative
action of this group of compounds. Treatment of HeLa cells with 4-methyl-,
4-fluoro-, 4-chloro-, 4-bromo- and 4-methoxy- derivatives of (E)-b-(benzoyl)
acrylic acid leads to the expression of cytostatic activity against HeLa cells
(IC50 were in the range from 31-40 µM). Their antiproliferative action was less
than that of the basic compound (E)-b-(benzoyl)acrylic acid whose IC50
was 28.5 µM. The 3,4-dimethyl-, 2,4-dimethyl- and 2,5-dimethyl- derivatives as
well as the 4-ethyl- and 3,4-dichloro- and 2,4-dichloro-derivatives, have
stronger cytostatic activity than the correspoding monosubstituted and parent
compound. Their IC50 were 18.5 µM; 17.5 µM; 17.0 mM; 17.5 µM; 22.0 µM and 18
µM, respectively. The 4-iso-propyl- and 4-n-butyl-derivatives
exerted higher cytostatic activity than the compounds with a lower number of
methylene -CH2- groups in the substitutent. Their IC50 were 14.5 µM
and 6.5 µM respectively. The 2,5-di-iso-propyl- and 4-tert-butyl-derivatives
expressed the most strong antiproliferative action against the investigated
HeLa cells, IC50 being 4.5 µM and 5.5 µM, respectively. The investigated
compounds affected the survival of HeLa cells, expressing a strong
structure-activity relationship of the Hansch type.
Key
words: benzoylacrylic acids, HeLa cells, cytotoxicity, QSAR.
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J.
Serb. Chem. Soc. 64(9) 513-518 (1999)
UDC 547.585:546.881.4:541.428.49
JSCS-2690
Original scientific paper
A polymeric oxovanadium(IV)
pyromellitate complex
DUSANKA D. VASOVIC and DJORDJE STOJAKOVIC
Faculty of Technology and
Metallurgy, University of Belgrade, Karnegijeva 4, P.O.Box 494, YU-11001
Belgrade, Yugoslavia
(Received
9 March 1999)
The
reaction of oxovanadium(IV) sulphate with 1,2,4,5-benzenetetracarboxylic acid
(pyromellitic acid) in the presence of potassium carbonate yields a polymeric
complex, K2[VO(pyr)]·6H2O (I) [pyr =
pyromellitate(4-) ion]. The PM3(tm) calculations and IR spectroscopy suggest
that the polymeric structure of I consists of -V-pyr-V-pyr- chains formed
by the 1,4- or 1,5-bridging by the pyr ions. The chains are additionally
cross-linked by the chelate function of one of the COO- groups of the pyr ion.
Magnetic measurements do not reveal the presence of antiferromagnetic coupling
between the V centers.
Key
words: oxovanadium(IV) complexes, pyromellitic acid, polymeric structure,
PM3(tm) calculations.
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J.
Serb. Chem. Soc. 64(9) 519-531 (1999)
UDC 546.719:547.554:541.428.49:542.9
JSCS-2691
Original scientific paper
A study of the effect of ammonia
gas on the solid mono- and dinuclear oxorhenium(V) complexes
M. M. MASHALY
Department of Chemistry, Faculty of
Education, Ain Shams University, Roxy, Cairo, Egypt
(Received
15 December 1998, revised 11 March 1999)
The
reaction of ammonia gas with the solid oxorhenium(V) complexes [Re2 O3L2Cl4]·2H2O, [Re2O2L3Cl6]·2H2O,
[ReOLCl(OH2)3]Cl2, [ReOL2(OH2)3]CCl3, [ReOLCl3(OH2)],
[ReOL(SCN)2Cl(OH2)]·H2O and [ReOL(SCN)Cl2(OH2)] (where L
= 2-benzimadazolethione), yielded the corresponding ammine and/or amine
complexes, [Re2O3L2(NH3)2(NH2)2]Cl2 (I), [Re2O2L3(NH3)2(NH2)4]Cl2 (II),
[Re2O3L2(NH3)2 (NH2)4]·H2O (III), [Re2O3L4(NH2)4] (IV),
[Re2O3L2(NH3)2(NH2)4C (V), [Re2O3L2(SCN)4(NH3)2] (VI)
and [Re2O3L2(Thio)2(NH2)4] (VII), respectively, (Thio = thiourea) where ammonia gas
has replaced other ligands such as chlorine and water. In complex VII
thiourea replaced the thiocyanate group in the start complex through its
reaction with ammonia gas. The obtained ammine and/or amine of rhenium(V)
complexes have been observed to decompose through several isolatable, as well
as non-isolatable complex species as intermediates during heating. [Re2O3L4], [Re2O3L2(NH2)4] and [Re2O3L2(SCN)4], were synthesized
pyrolytically in the solid state from the corresponding parent oxorhenium
complexes. The electronic absorption spectra and magnetic moments of the
complexes show that the Re(V) cation has an octahedral configuration. IR,1H-NMR
spectroscopy, conductivity measurements and thermal analysies show that ammonia
and thiourea behave as neutral monodentate ligands, SCN- and NH2- as
monodentate monoanionic ligands, the organic ligand (L) as a neutral monodentate
or bidentate ligand towards the metal cation.
Key
words: ammine and amine complexes, synthesis, magnetic properties,
electrical conductivity, 1H-NMR,
thermal analysis.
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J. Serb. Chem. Soc. 64(9) 533-538 (1999)
UDC 547.56:543.422:539.172.3:546.131
JSCS-2692
Original scientific paper
Protonation constants of
hydroxybenzenes in hydrochloric acid
D. S. VESELINOVIC, M. V. OBRADOVIC* and S. B. TOSIC*
Department of Physical Chemistry,
Faculty of Science, Studentski trg 12-16, P.O.Box 550, YU-11001 Belgrade and
*Chemistry Department, Faculty of Philosophy, YU-18000 Nis,
Yugoslavia
(Received
30 September 1998, revised 23 March 1999)
The
absorption spectra of monohydroxybenzene (Fen), 1,3-dihydroxybenzene (Rez),
1,4-dihydroxybenzene (Hi), 1,2,3-trihydroxybenzene (Pg) and
1,3,5-trihydroxybenzene (Fg) in aqueous solutions of hydrochloric acid with
different values of the Hammett acidity function(H0) have two absorption bands
in the region between 190-220 nm and 260-290 nm. This behavior is similar in
another mineral acids (H2SO4, H3PO4, HClO4). The
absorbance decreases with increasing of acidity (with decreasing of H0 values)
because of O-protonation. The absorption maxima shift to longer wavelengths,
and the graphic dependence of the absorption of the second band as a function
of H0 gives characteristic S-curves. These curves show the different
effect of the acid on the form the protonation of the investigated
hydroxybenzenes. The potonation constants of the hydroxybenzenes were
calculated: pKFen=-1.95; pKRez=-2.40; pKHi= -1.93; pKPg=-2.95; pKFg=-1.83.
Key
words: hydroxybenzenes, Hammett acidity function, hydrochloric acid,
protonation, UV spectra, S-curve, protonation constant.
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J.
Serb. Chem. Soc. 64(9) 539-552 (1999)
UDC 546.37:543.54:546.226/541.132/:541.18.041.5
JSCS-2693
Original scientific paper
Mechanism and kinetics of the
electrosorption of sulphate anions on the (111) face of silver
B. M. JOVIC, D. M. DRAZIC* and V. D. JOVIC**
Institute of Technical Sciences
SASA, P.O.Box 745, YU-11001 Belgrade,
*Institute of vElectrochemistry ICTM, P.O.Box 815, YU-11001
Belgrade and
**Center for Multidisciplinary Studies, University of Belgrade,
P.O.Box 33, YU-11030 Belgrade, Yugoslavia
(Received
25 April 1999)
The
processes of adsorption of sulphate anions onto the (111) face of silver have
been investigated by analysis of the cyclic voltammetry and potentiostatic
pulse results. It was shown, by fitting the experimentally recorded q - E
dependences, that the adsorption of anions follows Frumkin adsorption isotherm.
The adsorbed structure was found to be less dense than expected for the dense
packed anion monolayer and the process was characterized by high value of the
interaction parameter and the Gibbs energy of adsorption (f = 16.5 and DG°ads,q->0 = - 64 kJ
mol-1). From the slope of the Ep,a - log (c0)
dependence it was concluded that complete charge transfer between the adsorbed
anions and the silver substrate occurs. This is supported by the Ep,a - log v
linear dependence in the region of high sweep rates (v > 10 V s-1) with
rational value of line slope (~ 60 mV dec-1) which is
possible only if the complete charge transfer reaction occurs. The
electrosorption process of sulphate anions was found to be complex
electrochemical reaction, taking place through three steps. It was proposed
that the rate-determining step is the second step, i.e., the
electrochemical formation of (SO4)ads
species.
Key
words: (111) face of silver, sulphate anions, complete charge transfer,
Frumkin adsorption isotherm, mechanism and kinetics of electrosorption.
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J.
Serb. Chem. Soc. 64(9) 553-561 (1999)
UDC 661.887/666.363/:548.524/.55
JSCS-2694
Original scientific paper
Single crystals of bismuth silicon
oxide grown by the Czochralski technique and their characterisation
ALEKSANDAR GOLUBOVIC, SLOBODANKA NIKOLIC, RADOS GAJIC*, STEVAN
DJURIC** and ANDREJA VALCIC***
Institute of Chemistry, Technology
and Metallurgy, Njegoseva 12, YU-11000 Belgrade,
*Institute of Physics, Pregrevica 118, P.O.Box 57, YU-11001
Belgrade,
**Faculty of Mining and Geology, Djusina 7, P.O.Box 162, YU-11000
Belgrade, and
***Faculty of Technology and Metallurgy, Karnegijeva 4, YU-11000
Belgrade, Yugoslavia
(Received
23 November 1998, revised 11 May 1999)
Single
crystals of Bi12SiO20 were grown by the Czochralski technique. The critical diameter
and the critical rate of rotation were calculated. Suitable polishing and
etching solutions were determined. X-Ray measurements were performed on
powdered samples to obtain the lattice parameters. The optical properties of
the bismuth silicon oxide single crystals were investigated. The obtained results
are discussed and compared with published data.
Key
words: bismuth silicon oxide single crystals, Czochralski technique, critical
diameter, ciritical rate of rotation, etching solution, optical properties.
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