Esra Tanrıverdi Eçik

Competitive formation of cis and trans derivatives in the nucleophilic substitution reactions of cyclophosphazenes having a mono-spiro P–NHR group

Nucleophilic substitution reactions of N(3)P(3)Cl(4)[NH(CH(2))(3)NMe] (1) and N(3)P(3)Cl(4)[NH(CH(2))(3)O] (2) with mono-functional alcohols (methanol, 2,2,2-trifluoroethanol, phenol) and a secondary amine (pyrrolidine) were used to investigate the relationship between the incoming nucleophile and the proportions of products with substituents that are cis or trans to the spiro NH moiety. The reaction products were characterized by elemental analysis, mass spectrometry, (1)H and (31)P NMR spectroscopy and the configurational isomers by X-ray crystallography. Six products have been characterised with the substituent cis to the spiro NH group for the alcohol (methanol, phenol) and pyrrolidine derivatives of both compounds 1 and 2, compared to just one derivative with the substituent trans to the spiro NH group, that for the pyrrolidine derivative of compound 2. For each reaction the relative proportions of cis and trans isomers were determined by (31)P NMR measurements of the reaction mixtures. It was found that the reactions of compound 1 with all three alcohols and of compound 2 with methanol lead to exclusive formation of isomers with the substituent cis to the NH moiety, whereas all other reactions lead to mixtures of cis and trans isomers in different ratios under standard reaction conditions. However, when crown ether is included in the reaction medium for the reactions of compound 2 with both 2,2,2-trifluoroethanol and phenol, it is found that only cis isomers are formed. All these results are rationalised in terms of the competition between at least two effects; the cis-directing effect by hydrogen bonding of the incoming nucleophile to the spiro N-H group already present on the cyclophophazene ring and the cis-directing effect of the sodium cation coordinating to the oxygen lone pairs of the P-O moiety of the spiro ring.

BODIPY decorated dendrimeric cyclotriphosphazene photosensitizers: synthesis and efficient singlet oxygen generators

In the present work, syntheses of BODIPY decorated dendrimeric cyclotriphosphazenes (8–10) are described. The newly synthesized dendrimeric cyclotriphosphazenes have been characterized by 1H, 13C, 31P NMR spectroscopies, and UV-Vis electronic absorption spectra. These derivatives show absorption in the NIR region with good molar extinction coefficients. Singlet oxygen generation capacities of novel compounds (8–10) are measured using the trap molecule 1,3-diphenylisobenzofuran. BODIPY decorated dendrimeric cyclotriphosphazenes (8–10) demonstrate high singlet oxygen quantum yields. Also, each of them shows chemical and photostability under the conditions of singlet oxygen measurement. The dendrimeric cyclotriphosphazenes are proposed as potential photosensitizers that can be used as efficient singlet oxygen generators.

Octa-BODIPY derivative dendrimeric cyclotetraphosphazenes; photophysical properties and fluorescent chemosensor for Co(2+) ions.

We have designed and synthesized the first examples of fluorescent chemosensors based on octa-BODIPY decorated dendrimeric cyclotetraphosphazenes. The structures these synthesized compounds were verified by 1H, 13C, 31P NMR spectroscopies and UV-vis electronic absorption spectra. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotetraphosphazenes (OBCP 1-3) were investigated by fluorescence spectroscopy. OBCP 1-3 showed strong absorption in the 500-640nm region with high molar extinction coefficients. Additionally, octa-BODIPY decorated dendrimeric cyclotetraphosphazenes are candidate for fluorescent chemosensor for Co2+ showing high selectivity with a low limit of detection.

Characterization of paraben substituted cyclotriphosphazenes, and a DNA interaction study with a real-time electrochemical profiling based biosensor

AbstractThis paper describes an amperometric method for studying DNA-drug candidate interactions. It uses an automatted electrochemical biosensor (MiSens®) based on real-time electrochemical profiling and gold nanoparticles. A biochip was prepared from a 10 x 20 mm silicon dioxide wafer. The biochip surface is modified with a self-assembled monolayer and integrated into the microfluidic system. All the steps of the DNA-drug interaction assay have been performed during fluid flow. Biotinylated surface DNA has been captured on a NeutrAvidin -modified biochip surface. Hybridization of the complementary target sequence and biotinylated detection probe to the surface DNA strand was studied with and without the addition of newly synthesised drug candidates. NeutrAvidin and enzyme modified gold nanoparticles were then injected to bind to the biochip surface. The real-time reading of the amperometric response during the substrate injection results in the biosensor signal. The DNA interaction analysis was exemplarily applied to test the activity of paraben-substituted cyclotriphosphazenes as potential anticancer agents. Two of the synthesised compounds were identified that are capable of inducing DNA damage by 27 and 34%, respectively. Graphical abstractDNA-drug interactions can be investigated by an automated biosensor device that relies on Real-time Electrochemical Profiling (REP™).

Novel fully-BODIPY functionalized cyclotetraphosphazene photosensitizers having high singlet oxygen quantum yields

Abstract Novel fully-BODIPY functionalized dendrimeric cyclotetraphosphazenes (FBCP 1 and 2) have been synthesized and characterized by 1H, 13C and 31P NMR spectroscopies. The photophysical and photochemical properties of FBCP 1 and 2 are investigated in dichloromethane solution. The effectiveness of singlet oxygen generation was measured for FBCP 1 and 2 by UV–Vis spectra monitoring of the solution of 1,3-diphenylisobenzofuran (DPBF), which is a well-known trapping molecule used in detection of singlet oxygen. FBCP 1 and 2 show high molar extinction coefficients in the NIR region, good singlet oxygen quantum yields and appropriate photo degradation. The data presented in the work indicate that the dendrimeric cyclotetraphosphazenes are effective singlet oxygen photosensitizers that might be used for various areas of applications such as photodynamic therapy and photocatalysis.

Study on the Synthesis, Photophysical Properties and Singlet Oxygen Generation Behavior of Bodipy-Functionalized Cyclotriphosphazenes.

A new series of bodipy-functionalized cyclotriphosphazene derivatives were designed and synthesized. The identities of all newly synthesized compounds were confirmed by using 1H, 13C, 31P NMR spectroscopies. The photophysical properties of bodipy-functionalized cyclotriphosphazenes were investigated via absorption and fluorescense spectroscopies in dichloromethane. Singlet oxygen generation capacities of new compounds were also examined using the trap molecule 1,3-diphenylisobenzofuran. The targeted compounds showed high molar extinction coefficients in the NIR region and respectable singlet oxygen quantum yields when compared to that of methylene blue. The new bodipy-functionalized cyclotriphosphazenes are efficient photosensitizers to be potentially used for the singlet oxygen generation.

New hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates as highly selective and sensitive fluorescent chemosensor for Co 2+ ions

In the study, the new hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) have been successfully synthesized and characterized by using general spectroscopic techniques such as 1H, 13C and 31P NMR spectroscopies. The photophysical and metal sensing properties in THF solutions of dendrimeric cyclotriphosphazene conjugates (HBCP 1 and 2) were investigated by UV-Vis and fluorescence spectroscopies in dilute tetrahydrofuran solutions. These dendrimers showed strong absorption bands 501 and 641nm at low concentration with high molar extinction coefficients. In addition, the stoichiometry of the complex between the conjugate (HBCP 2) and Co2+ ions were determined by a Jobs plot obtained from fluorescence titrations. The metal sensing data showed that the hexa-bodipy functionalized dendrimeric cyclotriphosphazene conjugate (HBCP 2) is a candidate for fluorescent chemosensor for Co2+ ions due to showing high selectivity with a low limit of detection.

Synthesis, photophysical, DFT and photodiode properties of subphthalocyanine–BODIPY dyads

In this study, subphthalocyanine–borondipyrromethene conjugates have been successfully designed and synthesized. The novel compounds were fully characterized by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and 1H and 13C NMR spectroscopies. The photophysical properties of the conjugates were investigated by means of absorption and fluorescence spectroscopies in benzene solutions. The results showed that while the absorption spectra of both conjugates remain almost the same, compound 5 has a better fluorescence behavior and higher energy transfer efficiency. To test the effect of the replacement of the methyl group in the conjugates, Density functional theory (DFT) was used to calculate the equilibrium geometries of the ground state for the conjugates. The torsional angle of the BODIPY with reference to Sub-Pc in compound 5 (−125.4°) was different than that in compound 6 (−91.4°). This planarization results in a decrease in the orbital energy of the BODIPY unit in compound 5, making a smaller gap for the energy transfer mechanism between the BODIPY and Sub-Pc unit. In addition, their photodiode properties were tested here. The obtained phototransient current and capacitance results indicated that the devices exhibit both photodiode and photocapacitor properties. Therefore, it can be concluded that the subphthalocyanine–borondipyrromethene conjugate-based photodevices can be used as photodiodes in solar tracking systems.

A novel photosensitizer based on a ruthenium(II) phenanthroline bis(perylenediimide) dyad: synthesis, generation of singlet oxygen and in vitro photodynamic therapy

In this study, a novel photosensitizer having two perylenediimide units and a phenanthroline ruthenium(II) coordination moiety (Ru-BP) has been developed for photodynamic therapy (PDT) of cancer cells. This new compound was prepared via reactions of two newly designed molecules, namely, 5,6,12,13-tetrakis(4-(tert-butyl)phenoxy)-2-(2,6-diisopropylphenyl)-9-(4-hydroxyphenyl)anthra[2,1,9-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10(2H,9H)-tetraone (P6) and a bis(2,2′-bipyridyl)-(4,7-dichlorophenanthroline)ruthenium(II) complex (7). The singlet oxygen production of P6 and Ru-BP was investigated by a chemical method using 1,3-diphenylisobenzofurane as a trap molecule. Additionally, photodynamic therapy efficacy of the novel Ru-BP complex and P6 was evaluated in vitro. Ru-BP significantly decreased the viability of human chronic myeloid leukemia cells under red light but not in the dark, pointing out that the complex, itself, was not cytotoxic and singlet oxygen formation was required for the initiation of cell death mechanisms. Thus, Ru-BP can be effectively used as a photosensitizer in photodynamic therapy, which makes the novel Ru-BP a promising singlet oxygen generator for further biological applications.