JSCS - Vol 62, No 9- Abstracts

JSCS Vol 62, No 9

J. Serb. Chem. Soc. 62(9) 711-718 (1997)
JSCS-2441
UDK 06.055.5:54/66:486.1

One hundred years of the Serbian Chemical Society - 1897-1997

JOVAN JOVANOVIC

J. Serb. Chem. Soc. 62(9) 719-726 (1997)
JSCS-2442
UDK 547.923:542.91
Original scientific paper

Synthesis and oxidative transformations of 5-hydroxy-5a-cholest-8-en-3b-yl acetate

MIHAJLO M. MIHAJLOVIC, MILAN M. DABOVIC, VLADIMIR D. PAVLOVIC, NATALIJA M. KRSTIC and LJUBINKA B. LORENC

Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O.Box 158, YU-11001 Belgrade and ICTM - Center for Chemistry, Njegoseva 12, P.O.Box 815, YU-11001 Belgrade, Yugoslavia

(Received 16 May 1997)
5-Hydroxy-5a-cholest-8-en-3b-yl acetate (8) (prepared in 6 steps starting from 7-dehydrocholesteryl acetate (1) was transformed with ruthenium tetraoxide to 5-hydroxy-8,9-dioxo-8,9-seco-5a-cholestan-3b-yl acetate (9). Treatment of the later 8,9-seco-5-hydroxy derivates with lead tetraacetate(LAT) or mercuric oxide/iodine reagent (HgO/I₂) resulted, instead of the expected oxidative b-fragmentation of its C(5)-C(10) bond, in the competing non-regio and non-stereoselective acetoxylation of the a-positions next to the 8- and 9-oxo function (with LAT), and in the ~ 82% recovery of the starting material(with HgO/I₂). The results are discussed in terms of the strong hydrogen bonding which exists between the 5a-hydroxyl and the 8-oxo group.

Key words: 5-hydroxy-5a-cholest-8-en-3b-yl acetate, ruthenium tetraoxide oxidation of 8,9-seco-steroid derivative, reactivity.

J. Serb. Chem. Soc. 62(9) 727-735 (1997)
JSCS-2443
UDK 547.64:54.024.66.095.25
Original scientific paper

Cyclization/alkoxy radical fragmentation tandem: an efficient approach to the synthesis of bridged cyclooctane derivatives

RADOMIR SAICIC and ZIVORAD CEKOVIC

Faculty of Chemistry, University of Belgrade, Studentski trg 16, P.O.Box 158, YU-11001 Belgrade and ICTM - Center for Chemistry, Njegoseva 12, P.O.Box 815, YU-11001 Belgrade, Yugoslavia

(Received 16 May 1997)
In this paper an efficient synthetic approach to bridged cyclooctanone framework is described, which is based on cyclization/alkoxy radical fragmentation as a tactical combination of reactions. While the hypoidite reaction of alcohol 11 proceeds in a normal fashion, the hypobromite reaction of the same precursor unexpectedly affords dibromo derivative 14, which, in turn, shows unusual reactivity in the presence of cesium acetate.

Key words: cyclooctane, radicals, fragmentation, taxane, aldol reaction

J. Serb. Chem. Soc. 62(9) 737-748 (1997)
JSCS-2444
UDK 547.81:54.024
Original scientific paper

Synthesis of methyl 4-O-acetyl- and 4-acetamido-4-deoxy-2,3,6-tri-O-methyl-a-D-galacto- and a-D-glucopyranoside

DAVID YEAGLEY and MOMCILO MILJKOVIC

Department of Biochemistry and Molecular Biology, The Milton S. Hershey Medical center, The Pennsylvania State University, Hershey, PA 17033, USA

(Received 16 May 1997)
Using methyl 2,3,6-tri-O-methyl-a-D-glucopyranoside (12) as the common starting material the synthesis of methyl 4-O-acetyl and 4-acetamido-4-deoxy-2,3,6-tri-O-methyl-a-D-gluco- (1 and 3, respectively) and a-D-galactopyranosides (2 and 4, respectively) has been described. Synthesis of 12 from methyl 4,6,-O-benzylidene-a-D-glucopyranoside, via a series of regioselective blocking and deblocking reactions has also been described.

Key words: D-galactopyranoside, D-glucopyranozide, synthesis of

J. Serb. Chem. Soc. 62(9) 749-753 (1997)
JSCS-2446
UDK 547.74/.75:542.91
Preliminary communication

PRELIMINARY COMMUNICATION
New, flexible synthesis of 1,4,5,6-tetrahydrocyclopenta[b]pyrrol-4-ones

MILAN STOJANOVIC and YOSHITO KISHI

Department of Chemistry, Harvard University, Cambridge, MA 02138, USA

(Received 9 June 1997)
A novel approach to various pyrroles fused with cyclopentanones is described.

Key words: 1,4,5,6-terahydrocyclopenta(b)pyrrol-4-ones, synthesis of, bioluminwsence

J. Serb. Chem. Soc. 62(9) 755-768 (1997)
JSCS-2446
UDK 547.567.541.6
Original scientific paper

Structure and reactivity of steroidal quinones

DRAGANA R. MILIC, BOGDAN A. SOLAJA, LJILJANA DOSEN-MICOVIC, BELA RIBAR*, AGNES KAPOR*, DUSAN SLADIC and MIROSLAV J. GASIC

Faculty of Chemistry, University of Belgrade, Studentski trg 16,
P.O.Box 158, YU-11001 Belgrade and
*Institute of Physics, Faculty of Science, University of Novi Sad, Trg Dositeja Obradovica 4, YU 21000 Novi Sad, Yugoslavia

(Receiver 8 July 1997)
The preparation of substituted steroidal A-ring 1,4-quinones by nucleophilic addition results in pronounced regioselectivity at C(2), as confirmed by the X-ray analysis of 2-methoxy-2,5(10)-diene-1,4,17-trione. Conformational analysis (PM3, AMI, MNDO) of the suggested protonated intermediates and the difference in the relative energies of the transition states are considered. The results of cytotoxicity tests of selected quinones are also presented.

Key words: steroids, quinones, semi-empirical calculations, cytotoxicity

J. Serb. Chem. Soc. 62(9) 769-775 (1997)
JSCS-2447
UDK 547.781/.785
Original scientific paper

Novel dopaminergic/serotonergic ligands of 5-[2-(N,N-di-n-propylamino)-ethyl] benzimidazole series

VUKIC SOSKIC* ** and JELENA JOKSIMOVIC*

*Institute for Biological Research, 29. Novembra 142, YU-11000 Belgrade and
**Institute for Chemistry, Technology and Metallurgy, Njegoseva 12, YU-11000 Belgrade, Yugoslavia

(Received 9 June 1997)
A series of 5-[2-N,N-di-n-propylamino)-ethyl]benzimidazole derivatives has been synthesized by introducing different substituents into position 2 of the molecule. The resulting ligands were checked in vitro for their binding affinity at the dopamine (D₁ and D₂) and serotonin (5-HT_1A) receptors using synaptosomal membranes of the bovine caudate nuclei and hippocampi, respectively, and appropriate radioligands. None of the novel ligands expressed a binding affinity at the dopamine D₁ receptor. Compounds 1 and 10 were competitors of both [¹H]spiperone and [³H]-8-OH-DPAT. Compound 3 was inactive in displacing [3H]spiperone form the dopamine D₂ receptor, and compound 4 in displacing [³H]-8-OH-DPAT from serotonin 5-HT_1A receptor. The remaining seven novel ligands (2,5,6-9,11) expressed a moderate mixed dopaminergic/serotonergic activity with the affinity in the micromolar range of the concentrations. The fair affinity of compounds 11 and 8 produced by introducing very voluminous diphenylmethyl or 1-naphthylmethyl groups into position 2 of the parent compound, respectively, indicates that both the D₂ dopamine and 5-HT_1A receptor molecules are sterically very tolerant. The inactivity of ligands 3 and 10, interpreted by the electroststic repulsive interaction of the positively charged pyridyl groups and the above receptors, suggests that during design and synthesis of dopamine and serotonin agonist and antagonists, electroni effects should be aken into consideration.

Key words: dopaminergic, serotonergic, dopamine recepters, benzimidazoles

J. Serb. Chem. Soc. 62(9) 777-786 (1997)
JSCS-2448
UDK 615.777:547.962.5
Original scientific paper

Molecular features in the antifungal activity of thaumatin-like proteins from barley grain

ANA CVETKOVIC and JOVAN HRANISAVLJEVIC

Institute of General and Physical Chemistry, Studentski trg 12/V, P.O.Box 551, YU-11001 Belgrade, Yugoslavia

(Received 23 June 1997)
Leakage of cell constituents from brewers years was induced by incubation with thaumatin-like (TL) proteins isolated from barley grain. According to HPLC analysis, the released mixture is characterized by a broad molecular mass spectrum. It was partitioned by ultrafiltration into low- and high-molecular weight (MW) portions (membrane cut-off 10 kDa) and characterized by HPLC, SDS-PAGE and IEF. The low-MW portion consisted of eytoplasmic metabolites and the high-MW of periplasmic glycoproteins with MW values, 33-55 kDa and pl 4-6. Comparative experiments were performed with amphiphilic compounds which revealed a consistence of leakage effects with increasing hydrophobicity. Examination of the leaked cell constituents induced by incubation of yeast cells with dodecanoate and glycodeoxycholate sodium salts showed that the released mixtures were composed of cytoplasmic low-MW metabolites and high-MW nucleic acids. This suggests that thydrophobic molecules, as well as hydrophobic domains in TL-molecules generally determine the transmembrane transport from the cytoplasm while the basic groups in the TL-molecules participate in a specific detachment of periplasmic proteins.

Key words: PR-proteins, TL-proteins, barley, amphiphilic agents, brewers yeast, membrane permeabilization

J. Serb. Chem. Soc. 62(9) 789-799 (1997)
JSCS-2449
UDK 611-018:66.01:576.3
Review paper

REVIEW
Cell-polymer-bioreactor system for tissue engineering

GORDANA VUNJAK-NOVAKOVIC and LISA FREED

Division of Health Science and Technology, Massachusetts Institute of Technology,
Cambridge, MA 02139, USA

(Received 24 July 1997)
Tissue engineering is a new interdisciplinary field which combines the theoretical principles and practical approaches of biology, polymer chemistry and chemical engineering to create functional tissue substitutes for scientific studies and clinical applications. Isolated cells are stimulated to remodel their parent tissues in vitro by using biodegradable polymer scaffolds which provide a temporary 3-dimensional structure for tissue growth, and bioreactors which provide control over physiological parameters and hydrodynamic forces in the cell microenvironment. Highly porous polyglycolic acid scaffolds were specifically designed for tissue engineering and tested with respect to their biocompatibility, structure and degradation rate. Various tissue engineering bioreactors including static, well mixed and rotating vessels have been used in cultivations of natural and engineered tissues for up to 3 months. This paper reviews the use of cells, polymers and bioreactors to engineer cartilage and other tissues, and study tissue morphogenesis under controlled in vitro conditions. Some recent findings on the effects of bioreactor design and operating conditions on the structure, metabolic and biomechanical function of the growing tissue are also discussed.

Key words: tissue engineering, bioreactor, polyglycolic acid, cartilage

J. Serb. Chem. Soc. 62(9) 801-715 (1997)
JSCS-2450
UDK 541.124.2:541.122/.123:516.7
Original scientific paper

Response reactions: Interpretation and geometric representation

ISTVAN NAGYPAL, IVAN GUTMAN*, EUFROZINA HOFMAN and ILIE FISHTIK**

Institute of Physical Chemistry, Attila Jozef University, P.O.Box 105,
H-6701 Szeged, Hungary,
*Faculty of Science, University of Kragujevac, P.O.Box 60,
YU-34001 Kragujevac, Yugoslavia and
**University of North Carolina, Raleigh, NC 27606, USA

(Received 17 April 1997)
The concept of response reactions, elaborated in full detail in a few recently published papers, is interpreted in an alternative way, in order to make its chemical meaning easier to understand, and to visualize its most important features. The reaction extents in multiple-equilibrium systems are then interpreted in terms of response reactions. A geometric representation of the response reactions in three-component multiple-equilibrium systems is presented and a few illustrative examples provided.

Key words: response reactions, multiple-equilibrium systems, chemical thermodinamics

J. Serb. Chem. Soc. 62(9) 817-835 (1997)
JSCS-2451
UDK 546.271:535.14:543.423
Original scientific paper

Quantum chemical calculation of the electronic spectrum of the B₂H₂ radical. Comparison with spectra of related species

MILJENKO PERIC and BOJANA OSTOJIC

Faculty of Physical Chemistry, University of Belgrade, Studentski trg 16,
YU-11000 Belgrade, Yugoslavia

(Received 23 April 1997)
The singlet and triplet electronic states of the B₂H₂ radical are calculated by means of the quantum chemical ab initio method. The spectrum is compared with those of related molecular and atomic species. It is found that there is a great similarity between the global structures of the spectra of B₂H₂ and O₂. The nature of the binding in B₂H₂ is discussed in terms of the composition of the molecular orbitals and the molecular geometry dependence of their energy.

Key words: quantum chemistry, ab initio, B₂H₂ radical, electronic spectrum

J. Serb. Chem. Soc. 62(9) 837-845 (1997)
JSCS-2452
UDK 547.821.2:547.759.32:546.712-54-386
Original scientific paper

Transition metal complexes with thiosemicarbazide-based ligands.
Part XXXV. Pentagonal-bipyramidal manganese(II) complexes with 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone) (H₂L).
Crystal and molecular structure of [Mn(NCS)(H₂L)MeOH]NCS

VUKADIN M. LEOVAC, ERIKA Z. IVEGES, VALERIJA I. CESLJEVIC, VLADIMIR DIVJAKOVIC* and URLIH KLEMENT**

Institute of Chemistry, Faculty of Science, University of Novi Sad,
Trg Dositeja Obradovica 3, YU 21 000 Novi Sad,
*Institute of Physics, Faculty of Science, University of Novi Sad,
Trg Dositeja Obradovica 4, YU 21 000 Novi Sad, Yugoslavia and
**Institut fur Anorganische Chemie, Universitat Regensburg, Universitatsst. 31,
8400 Regensburg, Germany

(Received 18 June 1997)
The template reaction of warm alcoholic solutions of Mn(OAc)₂, S-methylisothiosemicarbazidehydrogen-iodide and 2,6-diacetylpyridine, in the presence of an excess of NH₄NCS yielded complexes of the general formula [Mn(NCS)(H₂L)ROH]NCS, where H₂L denotes the pentadentate N₅ ligand 2,6-diacetylpyridine bis(S-methylisothiosemicarbazone), and R = Me, Et. X-ray analysis of the MeOH complex showed its pentagonal-bypyramidal configuration (PBP), with the H₂L ligand in the equatorial plane, while the axial positions were occupied by one NCS group and a MeOH molecule. On the basis of IR spectra similar structure is supposed for the EtOH complex. the desolvate complex [Mn(NCS)₂(H₂L)], probably has a PBP structure too, in which both the axial positions are occupied by a NCS groups.

Key words: manganese(II) complexes, 2,6-diacetylpyridine bis(s-methylisothiosemicarbazone)

J. Serb. Chem. Soc. 62(9) 847-855 (1997)
JSCS-2453
UDK 547.964:542.93:546.98/541.428.49/
Original scientific paper

Compounds analogous to intermediates in hydrolytic cleavage of peptides by palladium(II) complexes

TATJAN N. PARAC and NENAD KOSTIC

Department of Chemistry, Iowa State University, Ames, IA 50011, USA

(Received 19 May 1997)
Reactions of cis-[Pd(en)(sol)₂]2+, in which en is ethylenediamine and sol is water or acetone, with dipeptide N-CBZ-Met-Gly-OEt(1) and its thioamide (symbol t) analog N-CBZ-Mett-Gly-OEt(2) are studied by ¹H- and ¹³C-NMR spectroscopy. The compound 1 reacts with cis-[Pd(en)(sol)₂]²⁺ forming the complex cis-[Pd(en)(N-CBZ-Met-Gly-OEt)(sol)]²⁺ (3), in which the peptide coordinates to palladium(II) via the sulfur atom in the side chain of methionine. This mode of coordination is favorable for the hydrolysis of the Met-Gly amide bond. The compound 2 reacts with cis-[Pd(en)(sol)₂]²⁺ and forms the complex cis-[Pd(N-CBZ-Met-Gly-OEt)(sol)₂]²⁺ (4), in which the thiopeptide coordinates to palladium(II) via two sulfur atoms, those in the methionine side chain and in the thioamide group. The bidentate coordination in 4 is unfavorable for the hydrolysis of the thioamide group, because the binding of thiocarbonyl group to palladium(II) results in the strengthening of the thioamide C-N bond. Therefore, the complex 4 is an unreactive analog of the reactive intermediate in the cleavage by external attack of solvent molecule. These studies with model complexes contribute to the understanding of the mechanism by which palladium(II) complexes hydrolyze peptides and proteins.

Key words: peptides, hydrolytic cleavage of, palladium(II) complexes

J. Serb. Chem. Soc. 62(9) 857-871 (1997)
JSCS-2454
UDK 539.125.41:539.183.5:543.42
Original scientific paper

Determination of absolute interproton distances by variable temperature two-dimensional cross-relaxation spectroscopy

NENAD JURANIC, ZSOLT ZOLNAI and SLOBIDAN MACURA

Department of Biochemistry and Molecular Biology, Mayo Graduate School, Mayo Clinic and Foundation, Rocheste, Minnesota 55905, USA

(Received 3 July 1997)
We propose to use the temperature dependence of laboratory frame cross-relaxation rate to deduce the absolute value of interproton distances in solutions. For rigid molecules undergoing random motion, the cross relaxation rate becomes zero at a characteristic temperature T₀, while at a higher temperature T_max it reaches its maximum. At T_max the correlation time is precisely defines and the interproton distance can be calculated directly from the cross-relaxation rate. The applicability of the method is tested on a small model compound, cyclo (L-Pro-Gly). For the geminal proton pair of glycin, the measured distance of 1.89±0.011A disagrees with the model value beyond the experimental error, indicating that the accepted model parameters need to be reevaluated.

Key words: NMR, cross-relaxation, distances, cyclo-(L-Pro-Gly)

J. Serb. Chem. Soc. 62(9) 873-884 (1997)

JSCS-2455
UDK 546.923:541.183:66.094
Original scientific paper

0₂ adsorption and reduction on Pt(111) modified with Br and Ag adlayers. an electrochemical and in situ X-ray diffraction study

R. R. ADZIC* ** and J. X. WANG*

*Chemical Science Division, Department of Applied Science,
Brookhaven National Laboratory, Upton NY 11973, USA and
**ICTM - Institute of Electrochemistry, Njegoseva 12, P.O.Box 815,
YU-11001 Belgrade, Yugoslavia

(Received 17 July 1997)
Structures of Br and Ag adlayers were determined on the Pt(111) in the absence and in the presence of O₂ reduction. On Pt(111), the commensurate (3x3) Br adlayer was found between 0.3 and 0.8 V in HClO₄ solutions. O₂ reduction is blocked by the (3x3) Br adlayer up to 0.5 V. At this potential, the ordered phase vanishes. Adsorbed disordered Br ions change the mechanism of O₂ reduction on Pt(111) from a 4e^- into a 2e^-reaction. Ag forms a hexagonal incommensurate bilayer at underpotentials while the first monolayer has a commensurate (1x1) structure. A complete inhibition of O₂ reduction on Pt(111) has been observed upon deposition of Ag monolayer. Analysis of the inhibition of O₂ reduction as a function of the Ag coverage shows that during reduction O₂ adsorbs in a bridge configuration on Pt(111).

Key words: oxygen electro reduction, oxygen adsorption, Pt(111) surface, Br adlayer, Ag adlayer

J. Serb. Chem. Soc. 62(9) 885-895 (1997)
JSCS-2456
UDK 567.261:541.138.2:541.135.52
Original scientific paper

Methanol oxidation on platinum single crystal surfaces in sodium bicarbonate solutions

A. V. TRIPKOVIC, K. DJ. POPOVIC, J. D. MOMCILOVIC and D. M. DRAZIC

ICTM - Institute of Electrochemistry, Njegoseva 12, P.O.Box 815, YU-11001 Belgrade, Yugoslavia

(Received 11 March 1997)
Methanol oxidation on platinum low-index surfaces was carried out in sodium bicarbonate solutions. It was shown that the low-index planes of platinum adsorb OH^- and bicarbonate anions, as well as "poisoning species". The surface activity was directly correlated to the OH_ad species coverage. The "poisoning species", produced during methanol oxidation, participate in the reaction at higher potentials, but partially block the surface at lower potentials. A dual path reaction mechanism was proposed based on the assumptions that HCO is a reactive intermediate and that formate is a reaction product in the main path, while CO₂ is a product of "poisoning species" oxidation in a parallel reaction path.

Key words: methanol oxidation, platinum single crystal, sodium bicarbonate, anion adsorption, reaction mechanism

J. Serb. Chem. Soc. 62(9) 897-903 (1997)
JSCS-2457
UDK 543.544:539.281
Original scientific paper

Log k pair linearity rule and proportionality rule in C₁₈ column chromatography

TOMISLAV JANJIC, GORDANA VUCKOVIC and MILENKO CELAP

Faculty of Chemistry, University of Belgrade, P.O.Box 158, YU-11001 Belgrade, Yugoslavia

It has been established that the two rules formulated for thin-layer salting-out chromatography - R_M pair linearity rule and Proportionality rule - can also be applied to C₁₈ column chromatography in all the cases where the Bosch model is valid, but instead of R_M values, the corresponding log k values are used. In addition, it has also been found that he obtained RPP values designate a new polarity scale for solvent systems.

Key words: C₁₈ column chromatography, mobile phase polarity parameter P_m^N, log k pair linearity rule, Proportinality rule

J. Serb. Chem. Soc. 62(9) 905-914 (1997)
JSCS-2458
UDK 546.49:542.61:547.498
Original scientific paper

Stabilization of mercury from precious metals extraction wastes utilizing trimercapto-s-triazine

LJILJANA SOLUJIC, MARK R. VAN DAJK*, EMIL B. MILOSAVLJEVIC and JAMES I. HENDRIX

Department of Chemical Engineering, Beadle Center, University of Nebraska,
Lincoln, NE 68588, USA and
*Department of Chemistry, University of Nevada, Reno, NV 89557, USA

(Received 9 June 1997)
The need for the removal of mercury from the precious metals extraction circuits may be influenced by process, environmental, as well as by occupational hazard reasons. In these circuits mercury is mainly present as cyanide complexes. The effectiveness of any stabilization method will be influenced by the high thermodynamic stability mercury-cyano species exhibit in an aqueous solution. In this study, we have investigated the utility of the trisodium salt of trimercapto-s-triazine (TMT, CAS No. 17766-26-6) for precipitation of mercury from the corresponding cyano-complexes. The influence of pH, mole ratio of TMT to Hg, coagulant and flocculant additions, excess of free cyanide, as well as the presence of other metal-cyano species on the effectiveness of mercury precipitation were investigated in detail. Also, a "real world" precisious metals mill effluent initially containint ~ 7 µg/mL (ppm) of Hg was treated and it was found that greater than 99.8% of the mercury was removed from the solution as an insoluble Hg/TMT complex.

Key words: trisodium trimercapto-s-triazine, Hg precipitation of