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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; Hokelek, Tuncer
    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 37. Syntheses and structural characterizations, biological activities of mono and bis(4-fluorobenzyl)spirocyclotetraphosphazenes
    (Royal Soc Chemistry, 2017) Elmas, Gamze; Okumus, Aytug; Sevinc, Pelin; Kilic, Zeynel; Acik, Leyla; Atalan, Mustafa; Hokelek, Tuncer
    The Cl substitution reactions of octachlorocyclotetraphosphazene, N4P4Cl8, with one equimolar amount of (4-fluorobenzyl)diamines (1-3) affords mono(4-fluorobenzyl) spirocyclotetraphosphazenes (4-6) as minor products. However, the reactions of N4P4Cl8 with two equimolar amounts of (4-fluorobenzyl) diamines (1-3) leads to the formation of mono (4-6), 2-trans-6-bis (7-9, as major products) and 2-cis-6-bis (4-fluorobenzyl) spirocyclotetraphosphazenes (10-12). The 2-cis-6-bis compounds (10 and 12) were separated and purified using column chromatography as minor products, whereas compound 11 could not be isolated. The mono-spiro (4-6) and 2-trans-6-bis-spiro (7-9) cyclotetraphosphazenes were reacted with excess pyrrolidine in THF to afford the fully substituted hexapyrrolidino (4a-6a) and tetra-pyrrolidino (7a-9a) products in high yield. Compound 9 was also reacted with piperidine, morpholine and 1,4-dioxa-8-azaspiro[4,5]decane (DASD) to obtain the tetraamino products (9b, 9c and 9d), respectively, due to its very high yield. The elemental analyses, mass spectra (ESI-MS), Fourier transform infrared (FTIR) spectra, and H-1, C-13{H-1}, and P-31{H-1} NMR data of the cyclotetraphosphazenes were in agreement with the suggested structures. The molecular structures of 7, 9 and 12 were established by X-ray crystallography. The antibacterial activities of the compounds against G(+) and G(-) bacteria and their antifungal activities against yeast strains were scrutinized. The results indicated that 4a and 5a were the most active compounds, especially to yeast strains. In addition, it was found that the most active compound toward DNA was 8. The cytotoxic activities of the cyclotetraphosphazenes against L929 fibroblast and MCF-7 breast cancer cell lines were elucidated. Compound 8a exhibited the most toxic effects against both types of cells.
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    Phosphorus-nitrogen compounds. part 38. Syntheses, characterizations, cytotoxic, antituberculosis and antimicrobial activities and DNA interactions of spirocyclotetraphosphazenes with bis-ferrocenyl pendant arms
    (Elsevier Science Sa, 2017) Elmas, Gamze; Okumus, Aytug; Cemaloglu, Resit; Kilic, Zeynel; Celik, Suheyla Pinar; Acik, Leyla; Hokelek, Tuncer
    The reactions of N4P4Cl8 (1), with two equimolar amounts of N-(1-ferrocenylmethyl)-N-methyl-propylenediamine gave the monoferrocenyl-spiro (as a byproduct), bisferrocenyl-2-trans-6-dispiro (2) and bisferrocenyl-2-cis-6-dispiro (3) cyclotetraphosphazenes. The 2-trans-6-dispiro (2) was reacted with excess monoamines to produce the tetraamino products (2a-2d). The one equimolar amount of the diamines and dialkoxides with 2 afforded the mono-diamino (2e and 2f) and mono-dialkoxy (2g and 2h) cyclotetraphosphazenes. Whereas, excess diamines and dialkoxides with 2 produced the bis-diamino (2i and 2j) and bis-dialkoxy (2k and 2l) bisferrocenyl-2-trans-6-dispirocyclotetraphosphazenes. The structures of the compounds were verified by elemental analyses, ESI-MS, FTIR, HSQC, HMBC, H-1, C-13, and P-31 NMR techniques. The molecular structures of 2 and 2b were established by X-ray crystallography. Compounds 2e and 2f have two stereogenic P-atoms. Additionally, the structures of 2i-2l containing tetraspiro rings in the skeletons look similar a propeller. The Fc groups of the cyclotetraphosphazenes were found to be redox active with two-reversible electron oxidations. The antimicrobial activity of the compounds was examined against some bacteria and yeast strains. The interactions of the compounds with DNA revealed that the compounds caused conformational changes even strand break on super-coiled DNA helix. Furthermore, the compounds (except 2, 2a and 2d) inhibited DNA restriction indicating compounds binding to A/A and G/G nucleotides of the DNA. The evaluations of the cytotoxic activity against L929 fibroblast and DLD-1 colon cancer cell lines were carried out. Some of the compounds were evaluated for antituberculosis activity against reference strain Mycobacterium tuberculosis H37Rv, and 2i and 2l displayed antituberculosis activity against H37Rv. (C) 2017 Elsevier B.V. All rights reserved.
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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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    Phosphorus-nitrogen compounds. Part 48. syntheses of the phosphazenium salts containing 2-pyridyl pendant arm: structural characterizations, thermal analysis, antimicrobial and cytotoxic activity studies
    (NATL INST SCIENCE COMMUNICATION-NISCAIR, 2020) Elmas, Gamze; Okumus, Aytug; Kilic, Zeynel; Ozbeden, Pelin; Acik, Leyla; Tunali, Beste Cagdas; Turk, Mustafa
    The phosphazenium salts (protic ionic liquids, PILs/protic molten salts, PMOSs) (6a-6d and 7a) of the free phosphazene bases (4a-4d and 5a) have been prepared by the reactions of the corresponding cyclotriphosphazenes with the bulky gentisic acid. The structures of the PMOS have been evaluated using the elemental analyses, FTIR, H-1, C-13{H-1} and P-31{H-1} NmR data. The molecular and crystal structures of 4a and 6c are established by X-ray crystallography. The thermal properties of the PMOS are determined using TG and DTA techniques. On the other hand, the antimicrobial activities of the free phosphazene bases (4a-4d and 5a-5d) and PMOSs (6a-6d and 7a) are screened against the selected bacteria and yeast strains. The antimicrobial activities of the free phosphazene bases and the PMOSs are compared. The interactions of the phosphazenes and their salts with plasmid DNA are elucidated by the agarose gel electrophoresis. The evaluations of the cytotoxic activities of these compounds are also studied against to L929 fibroblast and breast cancer cells (MDA-MB-231).
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    Phosphorus-nitrogen compounds. Part 64. Comparative reactions of spiro and ansa (N/O) cyclotetraphosphazenes with bulky (4-fluorobenzyl) N/N and N/O donor type bidentate reagents: structure, stereogenic properties and cytotoxic activity studies
    (Royal Soc Chemistry, 2022) Elmas, Gamze; Binici, Arzu; Yakut, Mehtap; Okumus, Aytug; Kilic, Zeynel; Cosut, Bunyemin; Hokelek, Tuncer
    The reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (1) (OCCP, tetramer), with an equimolar amount of sodium 3-(N-ferrocenylmethylamino)-1-propanoxide (L1) resulted in the formation of ferrocenyl-spiro-(2) and ferrocenyl-2-cis-4-dichloro-ansa-(3) cyclotetraphosphazenes. Both of the starting compounds were used to produce the new inorganic-organic hybrid multiheterocyclic-spiro and ansa cyclotetraphosphazenes. Spiro (2) was treated with excess N-(4-fluorobenzyl)-N'-ethyl-1,2-diaminoethane (L2) to give 2-trans-6-dispiro (trans-2a) and 2-trans-4-cis-6-trans-8-tetraspiro (tetraspiro-2a) cyclotetraphosphazenes. Spiro (2) was also reacted with excess sodium 3-(4-fluorobenzylamino)-1-propanoxide (L3) to produce 2-trans-6-dispiro (trans-2b), 2-cis-6-dispiro (cis-2b), 2-cis-4-trans-6-trispiro (trans-2c), 2-cis-4-dispiro-6-trispiro (cis-2c), 2-cis-4-dichloro-ansa-4-trans-6-spiro(N/O) (ansa-2b) and 2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/O) (ansa-2c). The reactions of 2,4-ansa (3) with excess L2 led to the formation of 2-cis-4-dichloro-ansa-2-trans-6-spiro(N/N) (trans-3a) and 2-cis-4-dichloro-ansa-2-cis-6-spiro(N/N) (cis-3a) cyclotetraphosphazenes. However, the reactions of 2,4-ansa (3) with excess L3 afforded monospiro {2-cis-4-dichloro-ansa-4-trans-6-spiro(N/O) (trans-3b) and 2-cis-4-dichloro-ansa-4-cis-6-spiro(N/O) (cis-3b)} and dispiro {2-cis-4-dichloro-ansa-6-trans-8-dispiro(N/O) (trans-3c) and 2-cis-4-dichEoro-ansa-6-cis-8-dispiro(N/O) (cis-3c)}. The obtained products were characterized by spectroscopic techniques. The crystal structures of trans-2b and cis-3b were clarified by single crystal X-ray analysis. The products had stereogenic P-centres except for trans-2a, tetraspiro-2a, trans-2b and cis-2b. The stereogenic properties of tetrameric phosphazenes were evaluated by X-ray crystallography and chiral high performance liquid chromatography (HPLC) methods. The structure of cis-3b revealed the absolute configurations of the enantiomers (SS'R ''/RR'S ''). The broad HPLC peak of cis-3b indicates that it may exist as a resamate in solution. The cytotoxic activities of the cyclotetraphosphazenes were evaluated using an MTT assay against L929 mouse fibroblasts, A549 non-small lung cancer and Caco-2 colorectal adenocarcinoma cells. Compound cis-3b was found to be very effective in all cell lines up to 104.1 mu M.
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    Phosphorus-nitrogen compounds: Part 31. Syntheses, structural and stereogenic properties, in vitro cytotoxic and antimicrobial activities, and DNA interactions of bicyclotetraphosphazenes containing bulky side group
    (Elsevier Science Sa, 2015) Mutlu, Gurcu; Elmas, Gamze; Kilic, Zeynel; Hokelek, Tuncer; Koc, L. Yasemin; Turk, Mustafa; Dal, Hakan
    Hexachlorocyclotriphosphazene, N3P3Cl6, and octachlorocyclotetraphosphazene, N4P4Cl8, were reacted with K2N2O2 salt of symmetric tetradentate ligand to obtain spiro-bino-spiro [(sbs) (2)] and 2,6-spiro-ansa-spiro [(2,6-sas) (3)] phosphazenes, respectively. The sbs was obtained in a very poor yield, whereas, 2,6-sas was obtained in a moderate yield. The derivatives of 2,6-sas with mono-and diamines were synthesized. When the reactions were carried out, one equimolar amount of 2,6-sas with an excess pyrrolidine, piperidine, morpholine, 1,4-dioxa-8-azaspiro[4,5]decane (DASD), N-methylethane1,2-diamine, N-ethylethane-1,2-diamine and N-methylpropane-1,3-diamine, along with the fully substituted 2,6-sas-cyclotetraphosphazene derivatives (4a, 4b and 5a-7a), were prepared. However, the excess morpholine and DASD with 2,6-sas yielded the geminal bis-(4c and 4e) and tris- (4d and 4f) cyclotetraphosphazenes, respectively. The Cl replacement reaction of 2,6-sas with one equimolar amount of 7 led to the formation of partly substituted 2,6-sas (7b). The structures of the compounds were verified by elemental analyses, MS, FTIR, H-1, C-13{H-1}, P-31 NMR, HSQC, HMBC and X-ray crystallography (for 3 and 4a) techniques. All the 2,6-sas cyclotetraphosphazenes (except 3, 4a and 4b) have stereogenic P-atoms. All the compounds were screened for antibacterial and antifungal activities against bacteria and yeast strains. The interactions of the compounds with supercoiled plasmid pBR322 DNA were investigated. The evaluations for cytotoxic activity, and apoptotic and necrotic effects against A549 lung cancer and L929 fibroblast cell lines were introduced. (C) 2015 Elsevier B.V. All rights reserved.
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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
    (2017) Okumuş, Aytuğ; Elmas, Gamze; Kılıç, Zeynel; Ramazanoğlu, Nagehan; Açık, Leyla; Türk, Mustafa; Akca, Gülçin
    The Cl replacement reactions of 4-fluorobenzyl(N/O)spirocyclotriphosphazene (2) with excess monoamines led to the formation of 4-fluorobenzylspiro(N/O)tetraaminocyclotriphosphazenes (2a2d). 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 31P NMR spectral data of the other dispiro phosphazenes were evaluated from the 31P 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
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    Synthesis of Bis(2,2,3,3-tetrafluoro-1,4-butanedialkoxy)-2-trans-6-bis(4-fluorobenzyl)spirocyclotetraphosphazene: Structural Characterization, Biological Activity and DFT Studies
    (SPRINGER/PLENUM PUBLISHERS, 2020) Elmas, Gamze; Kilic, Zeynel; Cosut, Bunyemin; Kesan, Gurkan; Acik, Leyla; Cam, Merve; Tunali, Beste Cagdas
    The Cl replacement reaction of octachlorocyclotetraphosphazene, N4P4Cl8 (1), with two equimolar amounts of N-(4-fluorobenzyl)-N'-methylpropane-1,3-diamine led to the formation of 4,4,8,8-tetrachloro-2-trans-6-bis-N-(4-fluorobenzyl)-N'-methylpropane-1,3-diamino-cyclotetraphosphazene (2). The reaction of 2 with excess sodium 2,2,3,3-tetrafluoro-1,4-butanedioxide afforded the bis(2,2,3,3-tetrafluoro-1,4-butanedialkoxy)-2-trans-6-bis(4-fluorobenzyespirocyclotetraphosphazene (2a). The elemental analyses, mass spectrum (ESI-MS), FTIR, HSQC, HMBC, H-1, C-13 and P-31 NMR spectral data of 2a were consistent with the proposed structure. The crystal structure of 2a was elucidated by X-ray diffraction method. The spectroscopic data of the molecules (2 and 2a) in the ground state were investigated by the Density Functional Theory (DFT) from the crystal structures. On the other hand, compound 2a was found to be the most active against S. aureus G(+) (MIC value: 125 mu M). Whilst, any antifungal activity of 2a was not observed against C. albicans and C. tropicalis. This compound also exhibits cytotoxic activity against L929 fibroblast and MCF-7 breast cancer cells. The interaction of 2a with pBR322 DNA was researched using gel electrophoresis. It is understood that the change in DNA conformation by interstrand of 2a with A/A and G/G nucleobases in DNA. [GRAPHICS] .
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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.