Ozlem Oter

Ratiometric sensing of CO2 in ionic liquid modified ethyl cellulose matrix

In this study emission-based ratiometric response of ion pair form of 1-hydroxy-3,6,8-pyrenetrisulfonate (HPTS) to gaseous CO(2) has been evaluated in ionic liquid (IL) containing ethyl cellulose (EC) matrix. The ionic liquid: 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF(4)); provided longer storage time and highly stable microenvironment for the HPTS molecule due to the buffering effect. The utilization of ionic liquid in ethyl cellulose matrix resulted with superior spectral characteristics. The excitation spectra of HPTS exhibited an atypical isoemmissive point in modified EC matrix at 418 nm which allows ratiometric processing of the signal intensities. EMIMBF(4)-doped sensor films exhibited enhanced linear working range between 0 and 100% pCO(2). The signal changes were fully reversible and the shelf life of the EMIMBF(4)-doped films was extended from 15 to 95 days.

An ultra sensitive fluorescent nanosensor for detection of ionic copper

A stable and ultra sensitive nano-scale fluorescent chemo-sensor for trace amounts of Cu(2+) was proposed. The Cu(2+) selective fluoroionophore 2-{[(2-aminophenyl)imino]methyl}-4,6-di-tert-butylphenol (DMK-7) was encapsulated in polymeric ethyl cellulose. The sensing membranes were fabricated in form of nanofibers and thin films. When embedded in polymers, the exploited DMK-7 dye exhibited enhanced photophysical characteristics in absorbance, Stokes shift, fluorescence quantum yield, and short and long-term photostability with respect to the solution phase. Sensing abilities of the nanofibers and thin films were tested by steady state and time resolved fluorescence spectroscopy. To our knowledge, this is the first attempt using the DMK-7-doped electrospun nanofibrous materials for copper sensing. The offered sensor displayed a sensitive response with a detection limit of 3.3×10(-13) M for Cu(2+) ions over a wide concentration range of 5.0×10(-12)-5.0×10(-5). Additionally, exhibited high selectivity over convenient cations; Na(+), K(+), Ca(2+), Mg(2+), NH4(+) and Ag(+), Al(3+), Ba(2+), Co(2+), Cr(3+), Fe(3+), Fe(2+), Hg(2+), Li(+), Mn(2+), Ni(2+), Pb(2+), Sn(2+) and Zn(2+).

Photocharacterization of Novel Ruthenium Dyes and Their Utilities as Oxygen Sensing Materials in Presence of Perfluorochemicals

Photophysical constants of three novel ruthenium dyes derived from tridentate pyridinediimine (pydim) ligands has been declared and their photoluminescent properties were investigated in solvents of dichloromethane (DCM), tetrahydrofuran (THF) and ethanol (EtOH) by UV-Visible absorption, emission and excitation spectra. The quantum yield, fluorescence decay time, molar extinction coefficient and Stoke’s shift values of the novel ruthenium complexes were determined. The perfluoro compound (PFC) nonadecafluorodecanoic acid which is also known as medical gas carrier has been used for the first time together with newly synthesized Ruthenium complexes in ethyl alcohol. The utilities of oxygen sensing materials were investigated in EtOH in presence of chemically and biochemically inert PFC.

Significant sensitivity and stability enhancement of tetraphenylporphyrin-based optical oxygen sensing material in presence of perfluorochemicals

Emission-based oxygen sensing properties of highly luminescent tetraphenylporphyrin molecules were investigated in polystyrene, ethyl cellulose, poly(1-trimethylsilyl-1-propyne) and poly(isobutylmethacrylate) matrices. The effect of perfluorochemicals (PFCs) on oxygen sensitivity and stability of the sensor materials was also examined. Fluorescence intensity and lifetime measurements of meso-tetraphenylporphyrinato Zn(II) (ZnTPP) and meso-tetraphenylporphyrin (H2TPP) materials were performed in the concentration range of 0–100% pO2. The fluorescence intensity variation of H2TPPvs. oxygen was 86%. H2TPP-based composite also yielded higher Stern–Volmer constant, faster response and regeneration time, excellent long term photostability and larger linear response range with respect to ZnTPP. The detection limit of oxygen for H2TPP was less than 0.5%. When stored in sealed bags protected from sunlight, no decrease in oxygen sensitivity was observed during approximately five months. As far as we know, the gathe...

Synthesis, structural characterization, oxygen sensitivity, and antimicrobial activity of ruthenium(II) carbonyl complexes with thiosemicarbazones

[Ru(CO)(PPh3)2(η3-O,N3,S-TSC1)] (1), [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC2)] (2), and [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC3)] (3) have been prepared by reacting [Ru(H)(Cl)(CO)(PPh3)3] with the respective thiosemicarbazones TSC1 (2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone), TSC2 (3-hydroxybenzaldehyde thiosemicarbazone), and TSC3 (3,4-dihydroxybenzaldehyde thiosemicarbazone) in a 1 : 1 M ratio in toluene and all of the complexes have been characterized by UV–vis, FT-IR, and 1H and 31P NMR spectroscopy. The spectroscopic studies showed that TSC1 is coordinated to the central metal as a tridendate ligand coordinating via the azomethine nitrogen (C=N), phenolic oxygen, and sulfur to ruthenium in 1, whereas TSC2 and TSC3 are coordinated to ruthenium as a bidentate ligand through azomethine nitrogen (C=N) and sulfur in 2 and 3. Oxygen sensitivities of 1–3 and [Ru(Cl)(CO)(PPh3)2(η2-N3,S-TSC4)] (4), and antimicrobial activities of 1–3 have been determined. Graphical Abstract Ru(II) carbonyl complexes were prepared by reacting [Ru(H)(Cl)(CO)(PPh3)3] with the respective thiosemicarbazone ligands and the complexes were characterized by UV–vis, FT-IR, and 1H and 31P NMR spectroscopy. Oxygen sensitivities and antimicrobial activities of the complexes were determined.

pH-Driven Fluorescent Switch Behavior of Azometine Dyes in Solid Matrix Materials

ABSTRACT Photoinduced switch behaviors of two dimethylamino-bearing azometine derivatives (AZM-I and AZM-II) were investigated in conventional solvents, polyvinyl chloride (PVC) and ethyl cellulose (EC) by means of absorption and emission spectroscopy. The fluorescence modulation of the molecular switches arises from increasing response of the exploited molecules to pH between pH = 6.00 and 11.00 in emission intensity at 590 and 582 nm. In the employed systems optical or chemical inputs are transduced into detectable spectroscopic outputs after the controlled exchange of protons between solution and membrane phases. In immobilized phases the attained reversible relative signal changes were very good; 97% and 99% for AZM-I and AZM-II respectively. Sensitivities of the molecular switches to most abundant anions and metal cations were also investigated. Except that of bicarbonate, Hg2+ and Ag+, presence of anions and metal cations in test medium did not restrict the proton sensing ability of the molecules.

Spectrofluorometric Determination of Carbon Dioxide Using 8-Hydroxypyrene-1,3,6-trisulfonic Acid in a Zeolite Composite

The monitoring of green house gas carbon dioxide of great global significance. In this study, a natural zeolite-polymer composite material was used for the first time for the sensing of dissolved and gaseous carbon dioxide with a spectrofluorimetric method. A carbon dioxide gas sensitive dye, 8-hydroxypyrene-1, 3, 6-trisulfonic acid, was used in its ion pair form either entrapped in the pores of zeolite-polymer composite as a thin film or in an electrospun polymer coated zeolite. The zeolite was modified with sodium hydroxide solution in order to supply a functional environment for the dye. The zeolite was preferred for its superior characteristics, including forming a porous, selective, and filtering layer to improve the selectivity and sensitivity of the sensor. The sensing membranes containing zeolites exhibited nearly a six-fold enhancement in the sensitivity and wide dynamic range between 0.0% and 100.0% gaseous carbon dioxide. The limits of quantification for gaseous and dissolved carbon dioxide were 0.5% and 9.89 × 10−6 mol/L, respectively. The zeolite-polymer composite films were stable for a longer period than the free zeolite films. No significant changes in the fluorescence intensity and sensor characteristics were observed over three months. Future work may involve other natural or synthetic zeolites with specific pore diameters for the design of task specific sensors.