Turan Ozturk

Novel Two-Band Ratiometric Fluorescence Probes with Different Location and Orientation in Phospholipid Membranes

3-hydroxyflavone (3-HF) derivatives are very attractive fluorescence sensors due to their ability to respond to small changes in their microenvironment via a dramatic alteration of the relative intensities of their two well-separated emission bands. We developed fluorescence probes with locations at different depths and orientations of 3-HF moiety in the phospholipid bilayer, which determine their fluorescence behavior. While the spectral shifts of the probes correlate with their binding site polarity, the intensity ratio is a complex parameter that is also sensitive to the local hydration. We demonstrate that even the deeply located probes sense this hydration effect, which can be modulated by the charge of the lipid heads and is anisotropic with respect to the bilayer plane. Thus the two-band ratiometric fluorescence probes can provide multiparametric information on the properties of lipid membranes at different depths.

A Berzelius Reagent, Phosphorus Decasulfide (P4S10), in Organic Syntheses

2.3. Amides and Lactams 3435 2.4. Imides 3448 2.5. Thiophenes 3451 2.6. Thiazolines, Thiazoles, and Thiazines 3454 2.7. Dithiazoles 3456 2.8. Thiadiazoles 3456 2.9. Imidazolines and Pyrimidines 3456 2.10. Alcohols 3458 2.11. PdO to PdS 3461 2.12. Reduction 3462 2.13. Nucleotides, Purines, and Pyrimidines 3463 2.14. Miscellaneous 3467 2.15. P4S10 vs Lawesson’s Reagent (LR) 3473 3. Conclusion 3473 4. Acknowledgments 3473 5. References 3473

Facile syntheses of 3-hydroxyflavones.

Modification of the present synthetic methods led to the syntheses of 3-hydroxyflavones in a shorter reaction time, with simple purification and higher yields. Application of the method provided the syntheses of 3HFs having a hydroxyl group on the phenyl ring (ring B) in one step, which is an improvement compared to the four steps, long reaction time, and low yield using the current method available in the literature.

Synthesis of furanochromones: a new step in improvement of fluorescence properties

New 3-hydroxychromone derivatives with a fused furan heterocycle (2-aryl-3-hydroxyfurano[3,2-g]chromones) have been synthesized. This was achieved by an important improvement in the synthetic procedure. Like their parent analogs, these new compounds exhibit two intensive fluorescence emission bands belonging to normal (N*) and tautomer (T*) excited-state forms. While the spectral position of the N* band remains unchanged, the T* band is shifted to longer wavelengths, providing larger separation between the two bands. The new compounds exhibit increased molecular extinction and, more importantly, have about twice as high fluorescence quantum yields. These properties make them very promising for designing new two-band fluorescence sensors.

Reversible Doping of a Dithienothiophene‐Based Conjugated Microporous Polymer

Dithienothiophene (DTT) based conjugated microporous polymers (CMPs) were synthesized by bulk and electrochemical oxidative polymerizations. Spectroelectrochemical measurements showed that DTT-CMP can be reversibly oxidized and reduced, accompanied by a significant change of the absorption properties making the material interesting for electrochromic devices. Reversible doping and dedoping of the bulk polymer network was also observed using iodine and ammonia, respectively. Nitrogen gas sorption measurements of the neutral, doped, and dedoped polymer networks indicated the presence of iodide species within the pores, and the conductivity of the networks is highly increased upon doping with iodine. The introduction of the strong electron donor DTT into a conjugated porous network, and the ability for redox switching, make DTT-CMPs interesting materials for organo(opto)electronic devices and sensors.

Long wavelength photoinitiated free radical polymerization using conjugated thiophene derivatives in the presence of onium salts

Long wavelength free radical photopolymerization of (meth)acrylic monomers using a conjugated thiophene derivative, namely 3,5-diphenyldithieno[3,2-b:2′,3′-d]-thiophene (DDT) and one of the following compounds, namely diphenyliodonium hexafluorophosphate (Ph2I+PF6−), triphenylsulfonium hexafluorophosphate (Ph3S+PF6−) and N-ethoxy-2-methylpyridinium hexafluorophosphate (EMP+PF6−), as photosensitizer and coinitiator, respectively, was described. Polymerization occurred only when DDT, in the presence of the onium salts, was irradiated at wavelengths where the salts have no absorption. A feasible initiation mechanism involves intermolecular electron transfer from photoexcited thiophene compound to the onium salt. The relative initiation efficiencies of the salts were investigated and evaluated in terms of their redox potentials.

Novel organoboron compounds derived from thieno[3,2-b]thiophene and triphenylamine units for OLED devices

Two novel D–A (donor–acceptor) and one D–A–D small molecules containing mesitylborane as an acceptor and triphenylamine as a donor, linked through a thieno[3,2-b]thiophene π-conjugated spacer, are synthesized and characterized. Their photo- and electrochemical properties were investigated by experimental and computational studies. The emission quantum efficiencies were determined to be between 46% and 68% in THF. Their solid-state quantum yields were recorded up to 42%. The fabricated electroluminescent devices as emitting materials showed sky-blue to yellowish green emissions. Their devices exhibit high performance with a turn-on voltage, maximal brightness, and highest luminescence efficiency of up to 4.0 V, 1200 cd m−2 and 1.13 cd A−1, respectively. These results pave new avenues for the future molecules possessing D and A units connected via fused thiophenes.

Controlled release of 5-aminosalicylicacid from chitosan based pH and temperature sensitive hydrogels.

A series of temperature and pH responsive hydrogels based on chitosan and poly(N-isopropyl acrylamide) (PNIPA) was prepared by redox polymerization. Effect of the composition on swelling behavior of the hydrogels and the release of 5-aminosaylcilic acid (5-ASA) at different temperatures and pHs have been investigated. Ammonium persulphate and TEMED were used as a redox pair at room temperature. As a cross linker, methacrylated chitosan was synthesized through the reaction of chitosan with glycidyl methacrylate (GMA). Introduction of the cross-linker provided the hydrogels with pH and temperature sensitivities. The phase transition temperatures of the hydrogels were determined by derivative differential scanning calorimeter (DDSC). Their phase transition temperatures were increased by chitosan content. Swelling behaviors and the release of 5-ASA varied significantly with pH, temperature and the gel composition. The release of 5-ASA from the hydrogels was followed by UV-Vis and fluorescence spectroscopy.

Synthesis of a chiral monosubstituted derivative of bis(ethylenedithio)tetrathiafulvalene: reaction of the cyclic sulfate ester of R,R-1,4-difluorobutane-2,3-diol with 2-thioxo-1,3-dithiole-4,5-dithiolate

2-Thioxo-1,3-dithiole-4,5-dithiolate reacts stereospecifically with the cyclic sulfate ester of R,R-1,4-difluorobutane-2,3-diol by two nucleophilic attacks, ring opening of the cyclic sulfate ester at carbon and displacement of the nearer fluorine atom, to form a derivative of the 1,3-dithiolo[4,5-b]-1,4-dithiin ring system. This product is converted in two steps into an analogue of bis(ethylenedithio)tetrathiafulvalene with a 2-fluoro-1-hydroxyethyl side-chain, a new substrate for the preparation of electroactive materials.

A class of sulfonamides as carbonic anhydrase I and II inhibitors

Abstract Four groups of novel sulfonamide derivatives: (i) acetoxybenzamide, (ii) triacetoxybenzamide, (iii) hydroxybenzamide and (iv) trihydroxybenzamide, all having thiazole, pyrimidine, pyridine, isoxazole and thiadiazole moieties were prepared and their inhibitory effects were studied on two metalloenzymes, i.e. carbonic anhydrase isozymes (hCA I and II), purified from human erythrocyte cells by Sepharose-4B-l-tyrosine-sulfanilamide affinity chromatography. These enzymes are present in almost all living organisms to catalyse the synthesis of bicarbonate ion (HCO3−) from carbon dioxide and water. The sulfonamide derivatives were found to be active against hCA I and II in the range of 2.62–136.54 and 5.74–210.58 nM, respectively.