Chemistry Journal of Moldova

The study has been focused on the comparative analysis of various analytical techniques for the injection of samples applied to detect the additives with flavouring potential that are used to obtainillicitly the "Muscat" and "Isabella" wines, by implementing the GC/MS method with injection of liquid samples directly into the capillary column, using the "Head-space" method and the solid phasemicroextraction (SPME).

Two new mononuclear coordination complexes constructed by non-covalent interactions, [Ni(phen)2(H2O)2](ClO4)2 (1) and [Cd(ClO4)2(phen)2] (2), where phen=1,10-phenanthroline, were synthesized and characterized by single-crystal X-ray diffractometry. The structural determination revealed that the coordination geometry around the Ni/Cd centres is distorted octahedral for each complex. In the complexes 1 and 2 the metal atoms have N4O2 coordination cores. In 1 the intermolecular OH···O hydrogen bonds, which involve the coordinating water molecules as donors and the perchlorate O atoms as acceptors form zigzag-like hydrogen-bonding chains, which are further assembled via π-π stacking interactions between adjacent phen rings, thus forming a supramolecular network structure. In the crystal structure of 2, π-π stacking interactions are noted between neighbouring hydrophobic phen ligands, yielding 1D supramolecular chains. The luminescence studies show that compound 1 displays blue luminescence, while compound 2 - white-light emission upon excitation with ultraviolet light.

Two crystalline compounds of germanium(IV) with malic acid (HMal) and 1,10ʹ-phenanthroline (phen) - [Ge(HMal)2(phen)]•pheh•2H2O (I) and [CuCl(phen)2][Ge(OH)(HMal)2] (II) were synthesized for the first time and characterized by elemental analysis, IR-spectroscopy and thermogravimetric analysis. There was elucidated from single-crystal X-ray diffraction that two different forms of Germanium are implemented: Ge4+ (I) and hydrolyzed GeOH3+ (II) to form distorted octahedron and pyramid respectively.

It has been conducted increase the yield up to 63% of ethyl 5-hydroxy-1,2-dimethyl-1H-3-indolecarboxylate via interaction of p-benzoquinone with N-methyl-b-aminocrotone ether in mixture of glacial acetic acid/ethyl acetate.

A series of homobi- and polynuclear zinc and cadmium coordination compounds supported by 1,2-cyclohexanedionedioxime (nioxime, NioxH2) and bridging bidentate ligands: 4,4'-bipyridyl (bpy), 1,2-bis(4-pyridyl) ethane (bpe), 1,3-bis(4-pyridyl) propane (bpp) and dipyridyl sulphide (dps) have been characterized by the experimental techniques of ¹H and ¹³C NMR spectroscopy. Individual NMR data of the compounds are consistent with their assignment as complexes.

The solvothermal reaction of zinc(II) nitrate with 1,2,3-benzenetricarboxylic acid (1,2,3-H3BTC) and 4,4ʹ-bis(imidazol-1-ylmethyl)biphenyl (BIBPh) produced a crystalline solid {[Zn3(BIBPh)3(BTC)2]∙H2O}n. The product has been structurally characterised and investigated by X-ray diffraction, IR and thermogravimetric methods. The polymer has a bidimentional structure and crystallizes in the P21/c space group of the monoclinic system with the following unit cell parameters: a= 14.8687(16), b= 36.915(4), c= 13.8378(16) (Å), β= 105.584(6)°. The asymmetric unit of the crystal structure contains three zinc(II) ions, three BIBPh ligands and two BTC3- monodentate ligands with all three deprotonated carboxylate groups that balance the overall charge. All zinc centers have similar coordination environment: each metal ion is four coordinated exhibiting a slightly distorted tetrahedral coordination, where two positions are occupied by oxygen atoms of the carboxylic acid and the other two by nitrogen atoms of imidazole subunits

4-(Dimethylamino)pyridine was found to be the homogenous and efficient catalyst for one-pot, multi-component reactions between hydrazine monohydrate, ethyl cyanoacetate, ketone, and malononitrile for the synthesis of 1,6-diamino-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarbonitrile derivatives using ultrasonication at room temperature in ethanol solution within 35-50 min with yields of over 90%. This procedure offers various remarkable features such as short reaction times, clean reaction condition, excellent yields, and easy work-up methods.

The study describes the synthesis of 11-homodrim-6,8-dien-12-oic acid N-substituted amides containing diazine, 1,2,4-triazole and carbazole rings based on commercially available sclareolide. The mentioned compounds were prepared for the first time by interaction of the generated in situ acyl chloride with some heterocyclic amines: 2- and 4-aminopyrimidine, 2-aminopyrazine, 3-amino-1,2,4-triazole and N-aminocarbazole. Their structures were fully elucidated by elemental and spectral analyses (IR, 1H and 13C NMR).

The synthesis and antiviral activity evaluation of new derivatives of 2-aminothiazole, 1,2,4-triazole, as well as oxindoles has been realized. The synthesized compounds exhibited different cytotoxicity, in particular, oxindols 4, 5 , 7 , 8 , 9, 10, 11, 12, 13, 58 as well as thiazole/triazole 73 and 75 turned out to be the most cytotoxic for MT-4 cell lines. The compounds 11, 12, 73, and 75 are more toxic than reference compound Efavirenz. As far as the antiviral activity is concerned, none of the title compounds turned out active against Reo-1, Sb-1, VSV, RSV, YFV and VV viruses. The results obtained against Bovine Viral Diarrhoea Virus (BVDV) showed that nine compounds (six from oxindol’s seria 6, 12, 13, 52, 56, 58 and three 73, 75, 77 of triazole homologues) resulted moderate active. Among all of them, the most potent compound was 52, with EC50 of 6.6 μM. Studies of effect of synthesized compounds against Coxsakie Virus (CVB-2) revealed that only two compounds, 13 and 73 exhibit moderate activity (EC50 >40 and >18 μM, respectively). It should be noticed that eleven compounds, 4, 5, 7, 8, 9, 10, 11, 12, 13, 58, and 75 showed moderate activity against HIV-1 (EC50 >16 – m >59μM).

The present study describes the synthesis of new five hybrid compounds, containing both di- or trinorlabdane and 2-amino-1,3-thiazole structural units with potential biological activity, based on natural labdane diterpenoide (-)-sclareol and its intermediate sclareolide. The structures of novel compounds were confirmed using IR, 1H, and 13C NMR analyses.

Several types of differently coloured crystals (light blue, blue and red) were obtained in the synthesis of assembled complex of mixed crystals with three metals by using solvent diffusion method. The mechanism of obtaining the assembled complexes is discussed based on the structure and colour change. The red crystal has 2D interpenetrated structure. The light-blue samples were [H2(bpp)][M(NCS)4] and they were built up spirally. The blue samples were M(NCS)2(bpp) and they formed 1D chain. [H2(bpp)][M(NCS)4] changed to 1D chain polymer (M(NCS)2(bpp)) by releasing HNCS from the cation and anion in a reaction vessel. Inductively Coupled Plasma Atomic Emission Spectroscopy, Electrospray Ionization Mass Spectrometry and X-Ray diffraction were used for characterization of the obtained complexes.

Synthesis of novel tetranorlabdane compounds bearing 1,3,4-thiadiazole units and intermediary tetranorlabdane compounds with thiosemicarbazone fragment has been reported. The structures of the new synthesized compounds were confirmed using IR and 1H, 13C, and 15N NMR spectroscopy. The in vitro antifungal and antibacterial activities of the mentioned compounds have been evaluated. Results of this study have shown that the 1,3,4-thiadiazole-2-imine has excellent activity against tested strains of fungi and species of bacteria at minimum inhibitory concentration values of 0.125 and 2.5 μg/mL, respectively.

The synthesis and characterization of [(5-mercapto-1,3,4-oxadiazol-2-yl)aryl]-3,5-diaryl-4,5-dihydro-1Hpyrazole-1-carbothioamides - derivatives of pyrazolines and 5-[4(3)-isothiocyanatophenyl]-2-thio-1,3,4-oxadiazoles were realized. The synthesized compounds, are crystalline substances, stable in storage and when exposed to air and light.

This study describes the synthesis of some novel compounds containing bis-1,3,4-oxadiazole bearing quaternary ammonium salt moieties. The target compounds were prepared from 2-(dimethylamino)ethyl methacrylate (DMAEMA) or 2-(diethylamino) ethyl methacrylate (DEAEMA), using adipic acid as starting material. All the newly synthesized compounds showed satisfactory analytic data for the proposed structures, which were confirmed by IR and NMR (¹H and ¹³C) spectroscopy. The newly synthesized compounds were evaluated for their antibacterial activity against various gram-positive and gram-negative strains of bacteria, and the antifungal activities were tested against three phytopathogenic fungi namely, Fusarium oxysporum, Fusarium commune and Fusarium rodelens. Some of the tested compounds displayed promising antibacterial and antifungal activities.

This article reports on the high yield synthesis and novel chalcones with isothiocyanate and imidazol groups. The synthesis was started from N,N-diphenilamine and finished with 4-(N,N-diphenylamino)-4’-(2-thioxo-imidazolidin-4-one)-chalcone, where the cheap and accessible reagents were used.

Starting with the methyl 11-homodrim-8-ene-7-oxo-12-oate a two steps synthesis of methyl-11-homodrim-6,8(9)-diene-12-oate was accomplished in 87% overall yield, which on photooxygenation in the presence of tetraphenylporphyrin gave a mixture of methyl esters of 11-homodrim-7-ene-6α,9α-peroxy-12-oic and 11-homodrim-5,8-diene-7-oxo-12-oic acids 21% and 54% yields, respectively.

This review deals the methods of preparation of the 11-bishomodrimane-8α-ol-12-one, a convenient synton for the synthesis of drimanic and bishomodrimanic compounds, including the biologically active ones. The triterpenic tetracyclic derivatives of the onoceranic range and the fragrance compounds with ambergris odour can be also obtained from this compound.

The selective one-step synthesis of 13-epi-manoyl oxide is reported based on a low-temperature superacidic cyclization of sclareol. The reaction conditions have been finely tuned in order to achieve a 9:1 ratio between epimeric oxides in favor of the desired 13-epi-oxide.

The known diterpenic ester – 15α-angeloyl-ent-kaur-16-en-19-oic (angeloylgrandifl oric) acid has been isolated from the dry wastes of Helianthus annuus L. The synthesis of 15α-hydroxy- and 15-oxo-ent-kaur-16-en-19- oic acids starting from ent-kaur-16-en-19-oic acid has been performed.

A relatively simple method for isolation of the mixture of ent-kaur-16-en-19-oic (1) and ent-trachiloban-19-oic (2) acids from dry waste of sunflower processing has been elaborated, and it has been shown that the waste can serve as an accessible source of ent-kauranic and ent-trachilobanic diterpenoids.

A mixture of 7α- and 17-bromonorambreinolides was obtained on treatment of the mixture of isomeric methyl bicyclohomofarnesenoates, the norambreinolide transesterification product, with NBS and H2O2. The structure of 7α- and 17-bromonorambreinolides was elucidated on the basis of spectral data. The structure of 17-bromonorambreinolide was confirmed by its reduction with LiAlH4 into sclaradiol, and that of 7α-bromonorambreinolide by X-ray analysis.