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    Phosphorus-nitrogen compounds. Part 42. The comparative syntheses of 2-cis-4-ansa(N/O) and spiro(N/O) cyclotetraphosphazene derivatives: spectroscopic and crystallographic characterization, antituberculosis and cytotoxic activity studies
    (Royal Soc Chemistry, 2019) Binici, Arzu; Okumus, Aytug; Elmas, Gamze; Kilic, Zeynel; Ramazanoglu, Nagehan; Acik, Leyla; Hokelek, Tuncer
    The reaction of N4P4Cl8 (1) with one equimolar amount of the sodium salt of an N/O donor-type bidentate ligand (2) afforded two kinds of derivatives, namely, mono-ferrocenyl-2-cis-4-dichloro-ansa- (2,4-ansa; 3) and mono-ferrocenyl-spiro- (spiro; 4) hexachlorocyclotetraphosphazenes. The reaction yield (35%) of 4 was significantly larger than that of 3 (14%). The 2,4-ansa compound (3) was reacted with excess secondary amines to produce 2-cis-4-dichloro-ansa-cyclotetraphosphazenes (3a-3d). On the other hand, the spiro compound (4) gave fully substituted mono-ferrocenyl-spiro-cyclotetraphosphazenes (4a-4d) with excess monoamines as well. The tetrameric phosphazene derivatives were characterized by ESI-MS and/or HRMS, FTIR, HSQC, HMBC, H-1, C-13, and P-31 NMR spectroscopy and X-ray crystallography (for 4). It is observed that the 2,4-ansa and spiro-cyclotetraphosphazenes have different thermal stabilities. Additionally, the CVs of the new mono-ferrocenyl pendant-armed cyclotetraphosphazenes revealed electrochemically reversible one-electron oxidation of the Fe-redox centre. The 2,4-ansa phosphazenes (3 and 3a-3d) have two different stereogenic P centers indicating that they are expected to be in racemic mixtures (RR'/SS'). The chiralities of 3a and 3c were investigated by chiral HPLC. The manuscript also deals with the antimicrobial activities against G(+)/G(-) bacteria and fungi, the interactions with plasmid DNA, the in vitro cytotoxic activities against L929 fibroblast and MCF7 breast cells, and the antituberculosis activities against Mycobacterium tuberculosis H37Rv of the cyclotetraphosphazenes.
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    The comparative reactions of 2-cis-4-ansa and spiro cyclotetraphosphazenes with difunctional ligands: Structural and stereogenic properties, electrochemical, antimicrobial and cytotoxic activity studies
    (Wiley, 2021) Okumus, Aytug; Elmas, Gamze; Kilic, Zeynel; Binici, Arzu; Ramazanoglu, Nagehan; Acik, Leyla; cosut, Bunyemin
    In this study, two kinds of compounds, namely, mono-ferrocenyl-2-cis-4-dichloro-ansa- (2,4-ansa; 3) and mono-ferrocenyl-spiro- (spiro; 4) hexachlorocyclotetraphosphazenes, were obtained by the Cl replacement reaction of N4P4Cl8 (1) with an equimolar amount of sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (2). The reactions of 2,4-ansa (3) with excess diamines and dialkoxides resulted in the formation of ansa-cyclotetraphosphazenes (3a-3e). Spiro (4) was reacted with excess diamines and dialkoxides to give the mono-ferrocenyl-spiro-cyclotetraphosphazenes (4a-4d). Although 2,4-ansa (3) produced the dispiro (3a) with N-(4-fluorobenzyl)-N '-methylethane-1,2-diamine, it afforded both monospiro (3b) and dispiro (3c) with N-(4-fluorobenzyl)-N '-methylpropane-1,3-diamine. However, spiro (4) yielded a trispiro (4a) with N-(4-fluorobenzyl)-N '-methylethane-1,2-diamine and 2,6-dispiro (4b) with N-(4-fluorobenzyl)-N '-methylpropane-1,3-diamine. The structures of the phosphazenes were elucidated by FTIR, ESI-MS and/or HRMS, spectroscopic and crystallographic (for 3f and 4b) data. Furthermore, the electrochemical findings of cyclotetraphosphazenes exhibited electrochemically reversible one-electron oxidation of Fe-redox centre. As an example, the chirality of 3c was investigated by P-31 NMR spectroscopy on the addition of (R)-(+)-2,2,2-trifluoro-1-(9 '-anthryl)-ethanol, chiral solvating agent (CSA). The circular dichroism (CD) (for 3d and 3e), HPLC (for 3d, 3e and 3f) and X-ray (for 3f) display that these compounds have chirality (RS ' or SR ') in the solution and solid state. This paper also focuses on the antimicrobial activities, the interactions with pBR322 DNA, in vitro anticancer activity against L929 fibroblast and MCF7 breast cells, and antituberculosis activity against Mycobacterium tuberculosis H37Rv of the cyclotetraphosphazenes.
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    The reactions of N3P3Cl6 with monodentate and bidentate ligands: the syntheses and structural characterizations, in vitro antimicrobial activities, and DNA interactions of 4-fluorobenzyl(N/O)spirocyclotriphosphazenes
    (Tubitak Scientific & Technological Research Council Turkey, 2017) Okumus, Aytug; Elmas, Gamze; Kilic, Zeynel; Ramazanoglu, Nagehan; Acik, Leyla; Turk, Mustafa; Akca, Gulcin
    The Cl replacement reactions of 4-fluorobenzyl(N/O)spirocyclotriphosphazene (2) with excess monoamines led to the formation of 4-fluorobenzylspiro(N/O)tetraaminocyclotriphosphazenes (2a-2d). The partly substituted dispiro 3b and dispiro 3c and fully substituted trispirocyclotriphosphazenes (trans 4a, cis 4c, 4d, and 4e) were obtained, respectively, from the reactions of 2 with one equimolar and two equimolar amounts of diamines, aminoalcohol, and diols. Although efforts were made for the separation of the cis/trans and optical isomers of the dispiro phosphazenes, only one set of diastereomers (RR/RS or SS/SR) of dispiro 3b and dispiro 3c was isolated, respectively. The P-31 NMR spectral data of the other dispiro phosphazenes were evaluated from the P-31 NMR spectra of the reaction mixtures. The reactions of 2 with excess N-methylethylenediamine gave trans 4a as a racemic mixture. While trans 4b (racemic) and cis 4b (meso) occurred from the reaction of 2 with excess N-methyl-1,3-propanediamine, they were not isolated separately. Some of the phosphazenes were screened against bacteria and fungi. The activities of the compounds against anaerobic and microaerophilic gram-negative bacteria were evaluated. It was found that compounds 2, 2b, and trans 4a exhibited tolerable toxic effects on fibroblast cells and had the highest toxicity against MCF-7 cells.