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    Phosphorus-nitrogen compounds. Part 35. Syntheses, spectroscopic and electrochemical properties, and antituberculosis, antimicrobial and cytotoxic activities of mono-ferrocenyl-spirocyclotetraphosphazenes
    (Royal Soc Chemistry, 2016) Okumus, Aytug; Elmas, Gamze; Cemaloglu, Resit; Aydin, Betul; Binici, Arzu; Simsek, Hulya; Acik, Leyla
    The reactions of octachlorocyclotetraphosphazene, N4P4Cl8, with N-alkyl-N-mono-ferrocenyldiamines, FcCH(2)NH(CH2)(n)NHR1 [n = 2, Fc = ferrocene, R-1 = Me (1); n = 2, R-1 = Et (2) and n = 3, R-1 = Me (3)], led to the formation of monoferrocenyl-spirocyclotetraphosphazenes (4-6). When the reactions were carried out with excess pyrrolidine, morpholine and 1,4-dioxa-8-azaspiro[4,5] decane (DASD), the fully substituted products (4a-6c) were obtained in high yields. The structures of all the phosphazene derivatives were characterized by MS, FTIR, H-1, C-13 and P-31 NMR, HSQC and HMBC techniques. The crystal structures of 4a and 5a were determined by X-ray crystallography. The electrochemically reversible one-electron oxidation of Fc redox centers was observed for cyclotetraphosphazenes. The fully substituted phosphazenes (4a-6c) were evaluated for their antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv, and compounds 4a-6a and 5c were found to be active. The antibacterial activities of phosphazenes 4a-6c against G(+) and G(-) bacteria and their antifungal activities against yeast strains were carefully scrutinized. The results indicate that compounds 4a-6a, 6b, 4c and 5c are very effective against yeast strains. The anticandidal activities of 6a and 6b make them promising anticandidal agents. The interactions of these compounds with plasmid DNA and their cytotoxic activity against L929 fibroblast and DLD-1 colon cancer cell lines were also investigated.
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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; Simsek, Hulya
    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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    Phosphorus-nitrogen compounds. Part 65. Novel diansa-spiro-cyclotetraphosphazenes: synthesis, characterization, bioactivity and electrochemical properties, and dye-sensitized solar cell fabrication studies
    (Royal Soc Chemistry, 2022) Mutlu, Gurcu; Okumus, Aytug; Elmas, Gamze; Kilic, Zeynel; Guzel, Remziye; Sabah, Busra Nur; Acik, Leyla
    In this investigation, the substitution reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (tetramer, OCCP, 1), with sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (L1) was found to yield the compounds, 2,4-ansa-(2) and spiro-(2) cyclotetraphosphazene derivatives. The starting hexachloro-2-cis-4-dichloro-monoferrocenyl-ansa-(N/O)cyclotetraphosphazene (2) reacted separately with dipotassium salts of N2O2 donor-type aminopodands, (KOPhCH2NH)(2)R [R = (CH2)(n), n = 2 (L2) and n = 3 (L3)], to produce mono-ferrocenyl-2,4-ansa-6,8-ansa-spirocyclotetraphosphazenes (dias; 3 and 4). Both products were purified by column chromatography, and their structures were confirmed using ESIMS, FTIR, H-1, C-13, and P-31 NMR spectral data. Besides, the molecular and crystal structures of 4 were elucidated by single-crystal X-ray diffraction. Compound 4 has four-different chiral P-centers. However, the absolute configuration of stereogenic P-centres of an enantiomer was designated as SS'S '' R'''. Both new compounds were also used for the examination of optical and electrochemical properties, and survey of bioactivity. To this end, the minimum inhibitory, bactericidal, and fungicidal concentrations (MIC, MBC, and MFC) were determined with the microdilution technique. These MIC, MBC, and MFC values were found to vary between 2500 mu M and 312.5 mu M. DNA cleavage activities of 3 and 4 with pBR322 plasmid DNA were also studied using electrophoretic mobility on an agarose gel. BamHI and HindIII restriction enzyme digestions of compound-pBR322 plasmid DNA were conducted to supply more insight into changes in DNA conformation. Cyclotetraphosphazene 4 caused DNA cleavage activity even at the lowest concentration. In addition to that, compound 4 inhibited enzyme digestion, indicating that DNA binds to A/A nucleotides with DNA binding activity. Moreover, the cytotoxicities of 3 and 4 were investigated by MTT assay against MDA-MB-231 breast cancer cells and COS-1 mammalian fibroblast cells. On the other hand, the optical and electrochemical properties of dias 3 and 4 were studied using UV-vis absorption and cyclic voltammetry techniques. As a result, both compounds can be suggested as ferrocene-based charge transformable phosphazene structures that can be used as new generation and synergistic DSSC materials.
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    Phosphorus-nitrogen compounds. Part 77. The synthesis of novel ferrocenyl(N/O)spiro- and 2-cis-4-dichloro-ferrocenyl(N/O)ansa-cyclotetraphosphazenes with 9-ethyl-3-carbazolyl pendant arm(s): spectral, bioactivity, electrochemical and dye-sensitized solar cell fabrication studies
    (Taylor & Francis Ltd, 2025) Mutlu, Gurcu; Yakut, Mehtap; Okumus, Aytug; Elmas, Gamze; Binici, Arzu; Guzel, Remziye; Sabah, Busra Nur
    Herein, the reactions of octachlorocyclotetraphosphazene (OCCP, 1) with sodium-3-ferrocenylmethyl-amino)-1-propanoxide (L1) gave hexachloro-ferrocenyl-(N/O)-spiro-2 and 2-cis-4-dichloro-ferrocenyl-(N/O)-ansa-3 cyclotetraphosphazenes in THF. Spiro- (2) reacted with excess 9-ethyl-N-methyl-3-carbazolyl-1,3-diaminopropane (L2) and 9-ethyl-N-ethyl-3-carbazolyl-1,2-diaminoethane (L3) to produce 2-trans-6-dispiro (dispiro-2a) and 2-trans-4-cis-6-trans-8-tetraspiro (tetraspiro-2b) cyclotetraphosphazenes, respectively. The reactions of ansa-3 with excess L2 led to the formation of monospiro {2-cis-4-dichloro-ansa-2-trans-6-spiro(N/N) (ansa-spiro-3b)} and dispiro {2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/N) (ansa-dispiro-3b)} cyclotetraphosphazenes. However, the reactions of ansa-3 with excess 9-methyl-N-ethyl-3-carbazolyl-1,2-diaminomethane (L4) afforded 2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/N) (ansa-dispiro-3a). Ansa-3 was also reacted with excess sodium 3-(9-ethyl-carbazolamino)-1-propanoxide (L5) to give 2-cis-4-dichloro-ansa-2-trans-6-spiro(N/O) (ansa-spiro-3c) and 2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/O) (ansa-dispiro-3c) cyclotetraphosphazenes. Reactions were carried out by classical and microwave-assisted methods. These novel multi-heterocyclic inorganic/organic hybrid cyclotetraphosphazenes can offer valuable insights into developing new materials. Tetraspiro-2b and all ansa compounds have more than one stereogenic P-atom. The optical and electrochemical properties of some cyclotetraphosphazenes were investigated using UV-vis absorption and cyclic voltammetry (CV) techniques. As a result, these phosphazenes can be suggested as ferrocene-based charge transformable structures. They can be used as new-generation and synergistic dye-sensitized solar cell (DSSC) materials. Additionally, antimicrobial activities of five compounds (dispiro-2a, ansa-spiro-3b, ansa-dispiro-3b, ansa-spiro-3c and ansa-dispiro-3c) against various pathogenic bacteria and yeasts were evaluated. Their interactions with pBR322 plasmid DNA were also investigated.
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    Phosphorus-nitrogen compounds: Part 60: Synthesis of hexaminomonoferrocenyl-spiro(N/O)cyclotetraphosphazenes: Spectral and electrochemical properties, tuning of redox feature, and antituberculosis activity
    (Taylor & Francis Ltd, 2023) Binici, Arzu; Elmas, Gamze; Okumus, Aytug; Guzel, Remziye; Simsek, Hulya; Kilic, Zeynel
    In the present investigation, the condensation reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (1) (tetramer, OCCP), with sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (L) resulted in the formation of the starting compound hexachloromonoferrocenylspiro(N/O)cyclotetraphosphazene (2). Thereafter, reactions of spiro (2) with excesses of 1-(2-aminoethyl)pyrrolidine, 1-(2-aminoethyl)piperidine and 4-(2-aminoethyl)morpholine in dry THF gave hexaaminomono-ferrocenylspiro(N/O)cyclotetraphosphazenes, 2a, 2b, and 2c, respectively. These new products were prepared for investigation of spectral and electrochemical properties, tuning of redox features, and examination of antituberculosis activities. The structures of 2a-2c were elucidated using elemental analysis, mass spectrometry (ESI-MS), FTIR, HMBC, HSQC, H-1, C-13 {H-1}, and P-31 {H-1} NMR data. The electrochemical behavior of these products containing monoferrocenyl group was investigated. Their use as potential alternative electrolyte redox couples for dye-sensitized solar cells (DSSC) was examined. The findings may inspire solar cell studies to explore the redox mediator behind the working mechanisms of DSSCs. Conversely, the antituberculosis activities of three compounds were examined against Mycobacterium tuberculosis H37Rv. The MIC values of 2a and 2 b were found to be as 30 and 35 mu g/mL, respectively, against the H37Rv reference strain.
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    Syntheses, structural characterization and biological activities of spiro-ansa-spiro-cyclotriphosphazenes
    (Royal Soc Chemistry, 2015) Basterzi, Nisan Sevin; Kocak, Selen Bilge; Okumus, Aytug; Kilic, Zeynel; Hokelek, Tuncer; Celik, Omer; Turk, Mustafa
    The replacement reactions of the Cl-atoms in partly substituted spiro-ansa-spiro-cyclotriphosphazenes (7 and 8) with excess pyrrolidine, 4-(2-aminoethyl) morpholine, and 1,4-dioxa-8-azaspiro[4,5] decane in dry THF led to the formation of heterocyclic amine substituted cyclotriphosphazenes (9a-c and 10a-c). All cyclotriphosphazene derivatives were characterized by elemental analysis, FTIR, MS, 1D H-1, C-13 and P-31 NMR and 2D HSQC, and HMBC techniques, and the crystal structure of partly substituted cyclotriphosphazene 8 was verified by X-ray diffraction analysis. Cyclotriphosphazene derivatives (5-8, 9a-c, and 10a-c) were subjected to antimicrobial activity against seven clinic bacteria and one yeast strain, and the interactions of the phosphazenes with plasmid pBR322 DNA were investigated. Phosphazene derivatives [(5, 7, 8, 9b and 9c) and (10a and 10b)] caused a slight increase and substantial decrease in the mobility of form I DNA, respectively, while 9a caused retardation on gel. Cytotoxic, apoptotic and necrotic effects against L929 fibroblast and A549 lung cancer cells were also evaluated. While the highest toxic effect was obtained for 9a in L929 fibroblast cells and for 9c in A549 lung cancer cells at 100 mg mL(-1) concentration, the highest apoptotic effect was determined for 10a in L929 fibroblast cells and for 9a in A549 lung cancer cells at the same concentration. It was found that 9a and 10b exhibited the most necrotic effects against L929 fibroblast and A549 lung cancer cells, respectively. The toxic and necrotic effects of the phosphazenes against A549 lung cancer cells were greater than those against L929 fibroblast cells, whereas, the apoptotic effect of the compounds was greater in L929 fibroblast cells than in A549 lung cancer cells.