JSCS Vol 71, No. 11
Adobe Acrobat version
|
These articles were
created using Adobe Acrobat and some were compressed using WinZip |
To download the latest |
|
|
To download the text of the whole issue
click here |
|
Impresum |
|
J. Serb. Chem.
Soc. 71 (11) 1125–1135 (2006) |
To download this article click here 107 KB |
Influence of N–1 substituent properties on binding affinities of
arylpiperazines to the binding site of 5-HT1A receptor
MARIO V. ZLATOVIC, VLADIMIR V. SUKALOVIC*, SLADJANA
V. KOSTIC-RAJACIC*, DEANA B. ANDRIC and GORAN M. ROGLIC
Faculty of Chemistry, University of Belgrade,
POB 158, 11000 Belgrade, Serbia
*ICTM, Department of
Chemistry, University of Belgrade, POB 473, 11000 Belgrade, Serbia
(Received 19 May, revised
24 July 2006)
Serotonin receptors
(5-HTRs), especially the 5-HT1A subtype, have been the subject of
intensive research for the past decade, due to their function in human
physiology. Several structurally different classes of ligands are known to bind
to the 5-HT1A receptor, but arylpiperazine derivatives are AMong the
most important ligands. In the work, docking analyses were used to explain the
binding affinities of a series of ligands with different N-1
substituent. All ligands had in common the arylpiperazine structure, while the N-1
substituent was modified to investigate the influence of ligand structure on
its binding affinity. The shape and size, as well as the rigidity of the
substituents were altered to investigate the possible effects on the formation
of the receptor – ligand complex.
Keywords: 5-HT1A, binding site, hydrophobic pocket,
arylpiperazine.
|
J. Serb. Chem.
Soc. 71 (11) 1137–1145 (2006) |
To download this article click here 99 KB |
Synthesis, characterization and spectroscopic
studies of the dihydrobis(1,2,3-benzotriazolyl)borate anion and its complexes
with MCl2·py2
KHWAJA S. SIDDIQI, AHMAD UMAR, SHAHAB A. A. NAMI
and SADAF KHAN
Department of Chemistry,
Aligarh Muslim University, Aligarh-202002, India
(Received 18 May 2005, revised 14 May 2006)
The preparation of
sodium dihydrobis(1,2,3-benzotriazolyl)borate was realised by refluxing one
mole of sodium borohydride with two moles of 1,2,3-benzotriazole in toluene
over a period of 12 h. Its complexes with MCl2·py2 [whereM=Mn(II),
Fe(II), Co(II), Ni(II), Cu(II) and py=pyridine] were characterized by elemental
analysis as well as magnetic, spectroscopic and conductivity measurements. On
the basis of these studies, it is proposed that the geometry of all the
complexes is octahedral. The ligand field parAMeters 10 Dq, B and b show extensive overlap between the M–L orbital. The molar
conductance of 10-3 M solutions of the complexes in DMSO suggest them to be
non-ionic in nature.
Keywords: borate, transition metal complexes, spectroscopy.
|
J. Serb. Chem.
Soc. 71 (11) 1147–1151 (2006) |
To download this article click here 87 KB |
Short communication
Stability of the
barium–benzo-15-crown-5 complex in nitrobenzene saturated with water
E. MAKRLÍK and P. VAURA*
Faculty of Applied
Sciences, University of West Bohemia, Husova 11, 306 14 Pilsen, Czech Republic
*Prague Institute of
Chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic
(Received 20 July 2005,
revised 21 March 2006)
From extraction
experiments and g-activity measurements, the
exchange extraction constant corresponding to the equilibrium Ba2+(aq)
+ SrL22+(nb) D BaL22+(nb) + Sr2+(aq)
occurring in the two-phase water–nitrobenzene system (L =benzo-15-crown-5; aq =
aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex
(Ba2+, SrL22+) = 0.3 ± 0.1. Furthermore, the
stability constant of the benzo-15-crown-5–barium complex in nitrobenzene
saturated with water was calculated for the temperature of 25 °C: log bnb (BaL22+)=13.3±0.1.
Keywords: barium, benzo-15-crown-5, stability constant, nitrobenzene.
|
J. Serb. Chem.
Soc. 71 (11) 1153–1160 (2006) |
To download this article click here 119 KB |
A study concerning the pretreatment of CNTs and
its influence on the performance of NiB/CNTs AMorphous catalyst
CHANG YUAN HU*,**, FENG YI LI*, LI HUA* and RONG BIN
ZHANG*
*Department of Chemistry, Nanchang University, Nanchang, Jiangxi 330047,
P.R. China
**Jiangxi Key Laboratory
of Nationals Surface Engineering, Jiangxi Science and Technology Normal
University, P.O. Box 224, Nanchang 330013, P.R. China
(Received 17 October 2005,
revised 6 March 2006)
As prepared carbon
nanotubes were pretreated with nitric acid (CNTs-HNO3) or AMmonia
(CNTs-NH3). Fourier transform infrared spectroscopy (FTIR)
measurements showed that the surface of the nanotubes was functionalized with
carboxylic and hydroxyl functional groups after the acid treatment and that
basic groups containing nitrogen, such as N–H and C–N, were introduced to the
surface of the nanotubes after the AMmonia treatment. X-Ray diffraction
analysis implied that the nickel residue in the CNTs was effectively removed by
acid treatment. However, the nickel residue was only partially eliminated by
AMmonia pretreatment. NiB AMorphous catalysts supported on CNTs-HNO3
and CNTs-NH3 were prepared by the impregnation–chemical reduction method
and characterized by transmission electron microscopy (TEM), as well as
inductively coupled plasma (ICP) spectroscopy and studied in the selective
hydrogenation of acetylene. TEM measurements showed that a high density NiB
particles of about 9 nm were homogeneously dispersed on the CNTs-NH3.
However, NiB particles (13–23 nm)with AMean size of 16 nm were scattered on the
CNTs-HNO3. As a result, the activity and selectivity of NiB/CNTs-NH3
were higher than those of NiB/CNTs-HNO3 in the selective hydrogenation
of acetylene.
Keywords: CNTs,
pretreatment, NiB AMorphous catalyst, acetylene selective hydrogenation,
AMmonia.
|
J. Serb. Chem.
Soc. 71 (11) 1161–1172 (2006) |
To download this article click here 135 KB |
Surface modification of a zeolite and the influence of pH and ionic strength on
the desorption of an AMine
JOVAN LEMIC, SINISA MILOSEVIC, MARIJA VUKASINOVIC*, ANA RADOSAVLJEVIC-MIHAJLOVIC
and DRAGANA KOVACEVIC
Institute for Technology
of Nuclear and Other Mineral Raw Materials, P. O. Box 390, 11001 Belgrade,
Serbia
Veterinary Specialized Institute, P. O. Box 390, 36000 Kraljevo, Serbia
(Received 31 October
2005, revised 16 February 2006)
The adsorption of stearyldimethylbenzylAMmonium
chloride (SDBAC) on the clinoptilolite–heulandite rich tuff in dependence on
the applied temperature was studied. The maximal AMount of sorbed SDBAC was 123
mmol/kg in the case of thermally treated zeolite tuff (100 °C) and a warm
surfactant solution (80 °C). The AMount and properties of water adsorbed on the
organo-zeolite (OZ) as well as the bonding between the organic species and the
zeolite were investigated by DTA, TG, DTG and IR analyses. During gradual
heating in an oxidizing atmosphere, the adsorbed organic material was oxidized,
giving rise to significant exothermic peaks. The adsorption of water vapor
decreased with increasing SDBAC loading up to 75 mmol/kg of zeolite, which can
be ascribed to an intensification of the hydrophobic characteristics of the
surface. With loadings above the 75 mmol/kg, the adsorption of water vapor
increased. Desorption of SDBAC from the organo-zeolite under environmentally
relevant conditions: distilled water, pH 3 and 10 buffers, as well as aqueous
NaCl and CaCl2 solutions, was investigated. OZs with loadings up to
their external cation exchange capacity value (75 mmol/kg) were stable under
all of the applied conditions.
Keywords: organo-zeolite, quaternary AMine, surface modification, ion
exchange.
|
J. Serb. Chem.
Soc. 71 (11) 1173–1186 (2006) |
To download this article click here 215 KB |
Activity and stability of RuO2-coated
titanium anodes prepared via the alkoxide route
VLADIMIR PANIC, ALEKSANDAR DEKANSKI, SLOBODAN
MILONJIC*, VESNA B. MISKOVIC-STANKOVIC** and BRANISLAV NIKOLIC**
ICTM-IEC, Njegoseva 12,
11000 Belgrade, Serbia
*Vinca Institute of
Nuclear Sciences, P. O. Box 522, 11001 Belgrade, Serbia
**Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4,
P. O. Box 3503, YU-11120, Belgrade, Serbia
(Received 12 May,
revised 24 July 2006)
Titanium anodes with an active RuO2
coating of two different thicknesses were prepared from the oxide suspended in
ethanol ("ink" method), while the oxide itself was synthesized by the
hydrolysis of ruthenium ethoxide in an ethanolic solution (alkoxide route). The
morphology of prepared oxide was exAMined by scanning electron microscopy. The
electrochemical properties of the prepared Ti/RuO2 anodes, involving
their cyclic voltAMmetric behavior in H2SO4 and NaCl
solutions, activity in the chlorine and oxygen evolution reaction, impedance
behavior in H2SO4, and stability during electrolysis in
dilute chloride solutions, were investigated. The performances of the anodes
are compared to those of a Ti/RuO2 anode prepared by the sol–gel
procedure from an oxide sol obtained by the forced hydrolysis of ruthenium
chloride in acid solution. The anodes prepared via the alkoxide route showed a
higher capacitance and activity for the chlorine evolution reaction than the
anode prepared by the inorganic sol–gel procedure. The results of the stability
test showed that the utilization of the coating active material is better when
the anodes were prepared via the alkoxide route than via the inorganic sol–gel
procedure, particularly for anodes with a smallermass of coating. The different
rates of loss of activity indicate a degradation mechanism for the anodes
prepared via the alkoxide route in which electrochemical dissolution of RuO2
from the coating surface prevails over the growth of an insulating TiO2
layer in the coating/Ti substrate interphase. The effect of RuO2
dissolution from the coating surface increases with increasing coating mass.
Keywords: RuO2 coating, alkoxide, ink method, ruthenium ethoxide,
chlorine evolution, anode stability.
|
J. Serb. Chem.
Soc. 71 (11) 1187–1194 (2006) |
To download this article click here 101 KB |
PRELIMINARY COMMUNICATION
Influence of chloride ions on the open circuit potentials of chromium in
deaerated sulfuric acid solutions
BORE JEGDIC, DRAGUTIN M. DRAZIC* and JOVAN P.
POPIC*
Institute for Chemical Power Sources, Batajni~ki drum bb, 11070 Belgrade-Zemun,
Serbia
*Institute of Chemistry, Technology and Metallurgy-Center for Electrochemistry,
P. O. Box 473, 11001 Belgrade, Serbia
(Received 20 October
2005, revised 13 January 2006)
Open circuit potential measurements and cyclic
voltAMmetry of chromium in deaerated aqueous H2SO4 solution
of pH 1 without and containing NaCl in the concentration range 0.5 – 4 M
revealed that chromium exhibits two stable open circuit potentials having the
character of a Wagner–Traud corrosion potential. One, Ecorr.1, was
established on the passive surface formed by exposing Cr previously to air or
passivated potentiostacially in a controlled manner, and the second one, Ecorr.2,
at the bare Cr surface obtained by prolonged cathodic activation. There is a
small difference in the Ecorr.1 values as a function of the passive
layer properties. Addition of NaCl accelerates the hydrogen evolution reaction
on the passive surface to some extent, while the sAMe reaction on the bare
surface was not affected by NaCl. On the other hand, presence of NaCl
accelerates the anodic reaction on the bare surface, and it activates the
dissolution of the passive layer so that the passive currents increase with
addition of NaCl. This effect is so large that at concentration of NaCl larger
than 3 M, the destruction of the passive layer was so fast that in a matter of
seconds the Cr was activated, and the only one stable corrosion potential
observed was Ecorr.2. No pitting of Cr in the presence of NaCl was
observed up to the transpassive potentials.
Keywords: chromium, corrosion, open circuit potential, sulfuric acid,
chloride ions.
|
J. Serb. Chem. Soc.
71 (11) 1195–1205 (2006) |
To download this article click here 134 KB |
Validation of an HPLC method for the
simultaneous determination of eletriptan and UK 120.413
MIRA ZECEVIC, BILJANA JOCIC, SNEZANA
AGATONOVIC–KUSTRIN* and LJILJANA ZIVANOVIC
Institute of Pharmaceutical Chemistry and Drug Analysis, Faculty of Pharmacy,
Vojvode Stepe 450, P. O. Box 146, 11000 Belgrade, Serbia
*Pharmacy M315, School of Biomedical, Biomolecular and Chemical Sciences, The
University of Western Australia, Crawley, W. A., 6009, Australia
(Received 2 December
2005)
Arapid and sensitive
RPHPLCmethod was developed for the routine control analysis of eletriptan
hydrobromide and its organic impurity UK 120.413 in Relpax® tablets.
The chromatography was performed at 20 °Cusing a C18 XTerraTM (5 m,
150 × 4,6 mm) column at a flow rate 1.0 ml/min. The drug and its impurity were
detected at 225 nm. The mobile phase consisted of TEA (1 %) – methanol
(67.2:32.8 v/v), the pH of which was adjusted to 6.8 with 85 % orthophosphoric
acid. Quantification was accomplished by the internal standard method. The
developed RP HPLC method was validated by testing: accuracy, precision,
repeatibility, specificity, detection limit, quantification limit, linearity,
robustness and sensitivity. High linearity of the analytical procedure was
confirmed over the concentration range of 0.05 – 1.00 mg/ml for eletriptan
hydrobromide and from 0.10 – 1.50 µg/ml for UK 120.413, with correlation
coefficients greater than r = 0.995. The low value of the RSD expressed
the good repeatability and precision of the method. Experimental design and a
response surface method were used to test robustness of the analytical
procedure and to evaluate the effect of variation of the method parAMeters,
nAMely the mobile phase composition, pH and temperature. They showed small
deviations from the method setting. The good recovery and low RSD
confirm the suitability of the proposed RP HPLC method for the routine
determination of eletriptan hydrobromide and its impurity UK 120.413 in Relpax®
tables.
Keywords: validation, RP HPLC, eletriptan hydrobromide, UK 120.413.
|
J. Serb. Chem.
Soc. 71 (11) 1207–1218 (2006) |
To download this article click here 106 KB |
Principal component articial neural network calibration models for the
simultaneous spectrophotometric estimation of
mefenAMic acid and paracetAMol in tablets
DONDETI SATYANARAYANA, KAMARAJAN KANNAN and RAJAPPAN MANAVALAN
Department of Pharmacy,
AnnAMalai University, AnnAMalainagar, TAMil Nadu – 60802, India
(Received 8 August 2005, revised 3 February 2006)
Simultaneous estimation
of all drug components in a multicomponent analgesic dosage form with
artificial neural networks calibration models using UV spectrophotometry is
reported as a simple alternative to using separate models for each component.
Anovel approach for calibration using a compund spectral dataset derived from
three spectra of each component is described. The spectra of mefenAMic acid and
paracetAMol were recorded as several concentrations within their linear range
and used to compute a calibration mixture between the wavelengths 220 to 340
nm. Neural networks trained by a Levenberg–Marquardt algorithm were used for
building and optimizing the calibration models using MATALAB® Neural
Network Toolbox and were compared with the principal component regression model.
The calibration models were throughly evaluated at several concentration levels
using 104 spectra obtained for 52 synthetic binary mixtures prepared using
orthogonal designs. The optimized model showed sufficient robustness even when
the calibration sets were constructed from a different set of pure spectra of
the components. The simultaneous prediction of both components by a single
neural netwook with the suggested calibration approach was successful. The
model could accurately estimate the drugs, with satisfactory precision and
accuracy, in tablet dosage with no interference from excipients as indicated by
the results of a recovery study.
Keywords: artificial neural networks, principal components,
UVspectrophotometry, mefenAMic acid, paracetAMol.
|
J. Serb. Chem.
Soc. 71 (11) 1219–1236 (2006) |
To download this article click here 152 KB |
The chemical characteristics of soil which
determine phosphorus partitioning in highly calcareous soils
ANA TOPALOVIC, LIDIJA B. PFENDT*, NATALIJA PEROVIC, DRAGANA DJORDJEVIC**,
SNEZANA TRIFUNOVIC*,** and PETAR A. PFENDT*,**
Biotechnical Institute, University of Montenegro, Kralja Nikole b.b., 81000
Podgorica, Montenegro
*Faculty of Chemistry,
University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia
**Center for Chemistry, Institute for Chemistry, Technology and Metallurgy ,
ICTM, Njegoseva 12, 11000 Belgrade, Serbia
(Received 12 December
2005, revised 26 February 2006)
Phosphorus fractions
from three highly calcareous soils (average, 24.9 ± 4.8 %CO32-)
from sAMpling sites with aMediterranean climate were isolated by sequential
extraction. In order to provide a more reliable basis for the definition of the
obtained P-fractions, principal component analysis was applied and from the
chemical characteristics of the 14 investigated soils, those characteristics
which define the content and association features of the P-fractions were
assessed. The soils are characterized by a relatively high pH (8.0 – 8.2) and
by significantly differing contents of organic mater, acid-soluble Mg and total
P. These differences affected the various association features of the
P-fraction with the soil constituents. The NH4F–P fraction (isolated
with 0.5 M NH4F, pH 8.2) is defined by the contents of the main
metals of the oxide–hydroxide–clay associations (Al, Fe,Mn) or by the the redox
potential (Eh) of Mn. The accumulation of NaOH–phosphorus (extractable
with 0.1M NaOH) depended on the constituents of the oxide–hydroxide–clay
association, the humic substances and Eh-related factors. In those soils
in whichNaOH–Pis defined by the oxide–hydroxide–clay assoiation, the
participation of Fe as a bridge-forming metal is proposed. The main part of
total P, i.e., DP = TP – (NH4F–P
+ NaOH–P) is defined by the status of Mn– and Fe–humic complexes or by the
concentration of hydroxyl-ions.
Keywords: NH4F–extractable P, NaOH–extractable P,
phosphorus-associations, principal component analysis.
|
J. Serb. Chem.
Soc. 71 (11) 1237–1246 (2006) |
To download this article click here 125 KB |
The sorption and crystallographic
characteristics of alumina activated in a reactor for pneumatic transport
LJILJANA ROZIC, TATJANA NOVAKOVIC, SRDJAN PETROVIC, ZELJKO CUPIC,
ZELJKO GRBAVCIC* and ALEKSANDAR ROSIC**
ICTM-Department of
Catalysis and Chemical Engineering, Njegoseva 12, Belgrade, Serbia
*Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4,
Belgrade, Serbia
**Faculty of Mining and
Geology, University of Belgrade, Djusina 7, Belgrade, Serbia
(Received 20 October
2005, revised 3 March 2006)
Active transition
alumina powders were obtained by flash calcination of gibbsite in a reactor for
pneumatic transport in the dilute, two-phase flow regime in the temperature
interval from 883 to 943 K with a residence time between 0.4 and 0.9 s. The
results of X-ray diffraction analysis confirmed that the activated alumina
sAMples were either microcrystalline or AMorphous. From nitrogen
adsorption–desorption isotherms, the specific surface areas of all sAMples were
calculated by the BETmethod. Using the sorption data, the fractal dimension of
the surface of the alumina sAMples was calculated according to a modified FHH
method. By application of fractal geometry, using the values of the fractal
dimension of the surface and of the specific surface area, the effective
surface areas of the active aluminas were calculated for the adsorption of
molecules having a cross-section area greater than that of the nitrogen
molecule
Keywords: pneumatic transport, transition AMorphous aluminas, X-ray
diffraction, fractal dimension.
Copyright &AMp; copy; SHD 2006.
January 15, 2007.
For
more information contact: JSCS@tmf.bg.ac.yu