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Učitelj ocjenjuje znanje učenika pomoću odabranog oblika ocjenjivanja. Ispisuje odnosno sastavlja razmatrane ciljeve, standarde znanja iz nastavnog kurikuluma, formira mrežni dijagram, ljestvicu bodova, sastavlja zadatke raznih vrsta te kriterije za stjecanje bodova.

Dehydroacetic acid (dha = 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one) is used as fungicide and in the synthesis of various organic compounds and complexes. Complexes of dha with transition metal ions are fungistatic. Reaction of 2-aminopyridine derivatives with dehydroacetic acid gives a novel pyridopyrimidines, which are obtained by opening of dehydroacetic acid ring. These compounds express good chelating properties and were used as polydentate ligands for synthesis of new dioxomolybdenum(VI) and oxovanadium(IV) complexes. All compounds were characterized by means of chemical analysis, IR spectroscopy, X-ray powder diffraction, and some by thermogravimetric analysis and single crystal X-ray diffraction method.

Intensive studies have been carried out during the last decade on the biochemical, pharmacological and physicochemical functions of molybdenum. In particular, many kinds of dioxomolybdenum compounds have been synthesized in order to study the catalytic oxygen atom transfer reactions as model of molybdoenzymes. Our investigations on the molybdenum(VI) complexes with salicylaldehyde and (L-asparagine, L-glutamine, L-ornithine hydrochloride) gave results which confirmed possible catalytic role of molybdenum in oxidative decarboxylation of aminoacids. The reaction of [MoO2(sal)2] and L-asparagine resulted in the yellow crystalline product [Mo2O5(sal-L-Asn)2] (1) and coumarine-3-carboxamide, (2) while in the reaction of [MoO2(sal)2] and L-ornithine (in hydrochloride form) a novel dissymmetric polydentate ligand coordinated to the molybdenum atom was obtained (3). All products were characterized by elemental analyses, IR and NMR data and X-ray analysis (3). We performed computational methods in order to investigate a possible mechanism for the reaction of [MoO2(sal)2] and L-ornithine.

Gamma-Type octamolybdates of the formulae, Na4[Mo8O26(alaO)2] * 18H2O (I), Na4[Mo8O26(glyglyO)2] * 15H2O (II) and Na4[Mo8O26(gly-glyO)2] * 12H2O (III) have been prepared from sodium molybdate in aqueous solution by adding DL-alanine or glycylglycine. Their crystal structures have been determined by X-ray structure analysis. DL-alanine and glycylglycine coordinate molybdenum atom in gamma-octamolybdate [Mo8O26]4- anions via monodentate carboxylate-oxygen atom. The prepared octamolybdates were screened for the possible antiproliferative activity on a panel of five tumor cell lines and on a normal cell line. All tested compounds showed a differential cell-growth inhibition in a dose-dependent manner selectively on hepatocellular carcinoma cell line (HepG2) and breast cancer cell line (MCF-7).

Two macrocyclic ligands N, N'-propylene-diylbis[3-(1-iminoethyl)-6-methyl-2H-pyran-2, 4(3H)-dione] I and N, N'-phenylene-diylbis[3-(1-iminoethyl)-6-methyl-2H-pyran-2, 4(3H)-dione] II have prepared by the condensation of dehydroacetic acid (3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one) with 1, 2-phenylenediamine and 1, 3-propylenediamine. They have been characterized by means of elemental analyses, IR spectroscopy as well as by x-ray crystallography. The x-ray studies confirmed the existence of strong N-H• • • O molecular hydrogen bonds in both structures.

Istražen je odnos morfologije monokristala tosiluracila i pripadajućeg Flackovog parametra

The investigations on polyoxomolybdates coordinated by organic ligands seem to be essential for understanding the antitumor activities of this class of compounds and modelling substrates involving in enzyme inhibition.1 In the course of our studies on polyoxometalates by amino acids2 and peptides we have prepared and characterized gamma-type octamolybdates coordinated by DL-alanine, Na4[Mo8O26(AlaO)2] • 18H2O (I) and glycyl-glycine, Na4[Mo8O26(glyglyO)2] • 12H2O (II). Both crystal structures consist of gamma-octamolybdate [Mo8O26]4- anions, sodium cations and water molecules with DL-alanine and glycyl-glycine coordinated via monodentate carboxylate – oxygen atom occupying the vacant sites of five coordinated molybdenum atoms in the gamma-[Mo8O26]4- anions. The effects of I and II, as well as of [Hmorph]4[Mo8O24(OH)2L2]• 4D (L = DL-alanine, DL-methionine, Hmorph = morpholinium cation, D = H2O or CH3OH) on proliferation of different human tumor cell lines (HeLa, SW620, HepG2, Hep-2, MCF-7 and human fibroblasts) have been investigated. All tested compounds have showed a significant "differential" cell-growth inhibition on HepG2 (hepatitic carcinoma) and MCF-7 (breast carcinoma) cell lines.

Beta'-Hydroxy-beta-enaminones containing 4-hydroxy-2-pyrone ring are known as good complexing agents and therefore are of interest in coordination and bioinorganic chemistry. The interest in these complexes derives from the possibility of their enzyme inhibitory properties owing to the interaction of the pyrone ring and enzyme active site. The molecular structure of compound (1) can be described as consisting of three structural fragments: 2-pyrone ring substituted by ethoxy group at position 6, delocalized central enaminone part and N-substituent (methoxycarbonylmethylammino group).

New molybdenum(V), [Mo2O4L12D2] (2), vanadium(IV), [VOL12], (3), and tungsten(VI), [WO2L12] (4), complexes have been obtained by the reaction of [Mo2O3(acac)4], [VO(acac)2] or Na2WO4• 2H2O (acac = acetilacetonate ion) with ethyl 4-hydroxy-3-[3-(methoxycarbonylmethylammino)-2-butenoyl]-2H-pyran-2-on-6-carboxylate, HL1, (1). In all complexes metals are coordinated by two ligands through two oxygen atoms only (as β -diketonate). Bonding of the ligand in such meaner provides the coordination of the monodentate solvent molecule D in the molybdenum complex (2). The complexes have been characterized by means of elemental analyses and IR spectra. The molecular structures of the ligand (1) and of the complex (3) have been confirmed by a single crystal X-ray diffraction study.