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FULYA TAKTAK

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Papers by FULYA TAKTAK

Research paper thumbnail of Spectroscopic Determination of Acid Dissociation Constants of Some Pyridyl Shiff Bases

Journal of Chemical and Engineering Data, 2006

The acid dissociation constants of twelve novel drug precursor N-substituted-6-acylbenzothiazolon... more The acid dissociation constants of twelve novel drug precursor N-substituted-6-acylbenzothiazolone derivatives were determined by using the UVÀvis spectroscopic technique. The protonation and deprotonation behaviors of the investigated molecules were researched from the super basic to super acid regions (i.e., 8 mol 3 L À1 KOH to 98% H 2 SO 4 ) including the pH region. It is observed that all of the molecules are protonated in the super acidic region. The calculated relative stability values of possible tautomer structures indicate that the keto form of investigated molecules is favored over the enol form. It was predicted that protonation occurs at the amide (oxo) group found in the keto form.

Research paper thumbnail of Micelles and ‘reverse micelles’ with a novel water-soluble diblock copolymer

Polymer, 2008

A series of poly [2-(diisopropylamino)ethyl methacrylate]-block-poly[2-(N-morpholino)ethyl methac... more A series of poly [2-(diisopropylamino)ethyl methacrylate]-block-poly[2-(N-morpholino)ethyl methacrylate], [PDPA-b-PMEMA], have been synthesized by using group transfer polymerization. These novel PDPA-b-PMEMA diblock copolymers dissolved molecularly in aqueous solution at low pH (<6.0) due to the protonation of all tertiary amine residues of both blocks and formed PDPA-core micelles at pH 7.5 by PMEMA block forming the micelle coronas. On the other hand, it was also observed that these diblock copolymers formed near-monodisperse 'reverse micelles', PMEMA-core micelles, in n-alkanes with or without requiring cosolvent depending on comonomer ratios. Dynamic light scattering studies indicated monodisperse or near-monodisperse micelles in both cases. The intensity-average radii of the PDPA-core and the PMEMA-core micelles were between 10 nm and 17 nm (polydispersity index, m 2 /G 2 < 0.08) and between 10 nm and 13 nm in n-hexane (m 2 /G 2 < 0.09), respectively.

Research paper thumbnail of Synthesis and physical gels of pH and thermo-responsive tertiary amine methacrylate based ABA triblock copolymers and drug release studies

Polymer, 2010

A series of novel pH-responsive ABA triblock copolymer gelators have been synthesized by using po... more A series of novel pH-responsive ABA triblock copolymer gelators have been synthesized by using poly [2-(diisopropylamino)ethyl methacrylate] (PDPA) as the A block and poly[2-(dimethylamino)ethyl methacrylate] (PDMA) as the B block via group transfer polymerization. While the PDPA-b-PDMA-b-PDPA triblock copolymers are molecularly soluble in acidic aqueous media due to protonation of all tertiary amine groups, they formed either gels by the chain-end hydrophobic interactions with relatively high polymer concentration (10 wt%) or near monodisperse "flower" micelles with low polymer concentration at neutral and basic aqueous solutions. The hydrophobic model drug release was studied in a sustained manner from the gels at pH 7.4 by varying the polymer concentration, the polymer molecular weight and the temperature of the medium. Preliminary studies indicate that both slow, sustained release and fast, triggered release of a model hydrophobic drug, dipyridamole, can be achieved by tuning the solution pH, polymer concentration, polymer molecular weight and temperature of the gel.

Research paper thumbnail of Synthesis and Selective Extractant Properties of a Calixarene Thioether Derivative and its Oligomeric Analogue

Herein we report the synthesis of a novel calix[4]arene thioether derivative (4) and its oligomer... more Herein we report the synthesis of a novel calix[4]arene thioether derivative (4) and its oligomeric analogue (5). The liquid-liquid extraction properties of these compounds towards the selected metal cations were evaluated, and it was concluded, based on our observations, that these compounds demonstrated remarkable affinity towards the selected metal cations. Nevertheless, 3 is a good extractant and very selective for Hg 2+ ions, whereas, in the case of its oligomeric analogue 5, the situation is quiet different.

Research paper thumbnail of Spectroscopic Determination of Acid Dissociation Constants of Some Pyridyl Shiff Bases

Journal of Chemical and Engineering Data, 2006

The acid dissociation constants of twelve novel drug precursor N-substituted-6-acylbenzothiazolon... more The acid dissociation constants of twelve novel drug precursor N-substituted-6-acylbenzothiazolone derivatives were determined by using the UVÀvis spectroscopic technique. The protonation and deprotonation behaviors of the investigated molecules were researched from the super basic to super acid regions (i.e., 8 mol 3 L À1 KOH to 98% H 2 SO 4 ) including the pH region. It is observed that all of the molecules are protonated in the super acidic region. The calculated relative stability values of possible tautomer structures indicate that the keto form of investigated molecules is favored over the enol form. It was predicted that protonation occurs at the amide (oxo) group found in the keto form.

Research paper thumbnail of Micelles and ‘reverse micelles’ with a novel water-soluble diblock copolymer

Polymer, 2008

A series of poly [2-(diisopropylamino)ethyl methacrylate]-block-poly[2-(N-morpholino)ethyl methac... more A series of poly [2-(diisopropylamino)ethyl methacrylate]-block-poly[2-(N-morpholino)ethyl methacrylate], [PDPA-b-PMEMA], have been synthesized by using group transfer polymerization. These novel PDPA-b-PMEMA diblock copolymers dissolved molecularly in aqueous solution at low pH (<6.0) due to the protonation of all tertiary amine residues of both blocks and formed PDPA-core micelles at pH 7.5 by PMEMA block forming the micelle coronas. On the other hand, it was also observed that these diblock copolymers formed near-monodisperse 'reverse micelles', PMEMA-core micelles, in n-alkanes with or without requiring cosolvent depending on comonomer ratios. Dynamic light scattering studies indicated monodisperse or near-monodisperse micelles in both cases. The intensity-average radii of the PDPA-core and the PMEMA-core micelles were between 10 nm and 17 nm (polydispersity index, m 2 /G 2 < 0.08) and between 10 nm and 13 nm in n-hexane (m 2 /G 2 < 0.09), respectively.

Research paper thumbnail of Synthesis and physical gels of pH and thermo-responsive tertiary amine methacrylate based ABA triblock copolymers and drug release studies

Polymer, 2010

A series of novel pH-responsive ABA triblock copolymer gelators have been synthesized by using po... more A series of novel pH-responsive ABA triblock copolymer gelators have been synthesized by using poly [2-(diisopropylamino)ethyl methacrylate] (PDPA) as the A block and poly[2-(dimethylamino)ethyl methacrylate] (PDMA) as the B block via group transfer polymerization. While the PDPA-b-PDMA-b-PDPA triblock copolymers are molecularly soluble in acidic aqueous media due to protonation of all tertiary amine groups, they formed either gels by the chain-end hydrophobic interactions with relatively high polymer concentration (10 wt%) or near monodisperse "flower" micelles with low polymer concentration at neutral and basic aqueous solutions. The hydrophobic model drug release was studied in a sustained manner from the gels at pH 7.4 by varying the polymer concentration, the polymer molecular weight and the temperature of the medium. Preliminary studies indicate that both slow, sustained release and fast, triggered release of a model hydrophobic drug, dipyridamole, can be achieved by tuning the solution pH, polymer concentration, polymer molecular weight and temperature of the gel.

Research paper thumbnail of Synthesis and Selective Extractant Properties of a Calixarene Thioether Derivative and its Oligomeric Analogue

Herein we report the synthesis of a novel calix[4]arene thioether derivative (4) and its oligomer... more Herein we report the synthesis of a novel calix[4]arene thioether derivative (4) and its oligomeric analogue (5). The liquid-liquid extraction properties of these compounds towards the selected metal cations were evaluated, and it was concluded, based on our observations, that these compounds demonstrated remarkable affinity towards the selected metal cations. Nevertheless, 3 is a good extractant and very selective for Hg 2+ ions, whereas, in the case of its oligomeric analogue 5, the situation is quiet different.

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