Browsing by Author "Içli S."
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Item Photophysical and photochemical characteristics of an azlactone dye in sol-gel matrix; a new fluorescent pH indicator(2003) Ertekin K.; Karapire C.; Alp S.; Yenigül B.; Içli S.The photophysical and photochemical properties of an azlactone derivative, 4-(p-N,N-dimethylaminophenylmethylene)-2-phenyl-5-oxazolone, (DPO) in a sol-gel matrix have been examined. The fluorescence quantum yield, radiative lifetime, fluorescence lifetime, fluorescence rate constant and singlet energy values of the DPO dye were determined in a modified tetraethyl orthosilicate (TEOS) solid matrix by absorption and emission spectroscopy and obtained data were compared with the results of measurements in acetonitrile (MeCN) and tetrahydrofuran (THF) solution. The sol-gel matrix enhanced the fluorescence quantum yield (Qf=0.296) and fluorescence emission lifetime (τf=0.47 ns) compared to Qf=0.0027-0.0025 and τf=0.02-0.03 ns for solutions in MeCN and THF. The acidity constant of DPO was found to be as pKa=5.1 in the transparent sol-gel matrix. The dye doped sol-gel exhibited a pH sensitivity in pH range 3.0-7.0. © 2002 Elsevier Science Ltd. All rights reserved.Item A study on photophysical properties of some Vitamin K3 derivatives(2004) Hakli O.; Karapire C.; Posokhov Y.; Içli S.Photophysical properties of menadione sodium bisulfite (MSB), menadione nicotinamide bisulfite (MNB) and menadione dimethylpyrimidinol bisulfite (MPB) were studied in their aqueous solutions. They are oil-soluble vitamins and not naturally fluorescent, however, it is possible to gain fluorescent signal by the use of phosphate buffer solutions containing sodium dodecyl sulfate (SDS) at optimum concentration. The quantum yields of fluorescence emission, Φ f, were measured as ∼10-4, 0.0085 and 0.053 for MSB, MNB, MPB, respectively. Fluorescence quenching with Co2+ ions yielded the quenching rates of 1.7×109, 4.6×1010, and 1.5×1010 M-1 s-1 for MSB, MNB and MPB, respectively. Calculated Gibbs free energy (Δ G) values (≤-5 kcal/mol) of the compounds suggest that electron transfer could be the reason of quenching with Co2+ ions. Studied derivatives were found to give two electrons. Equilibrium constants (Keq) derived from Δ G values pointed out strong association between the pairs of MSB, MNB and MPB complexes. They were irradiated by using not only artificial Xe lamp of fluorescence spectrophotometer, but also by using direct and concentrated sunlight and degradation (%), rate constant (kp) and half-lives (t1/2) were compared. Photodegradation (%) of Vitamin K3 derivatives varied depending on the irradiation source. Photostability tests pointed out MPB as the most stable derivative. © 2004 Elsevier B.V. All rights reserved.Item Photoinduced electron transfer-catalyzed processes of sulfoamino perylene diimide under concentrated sun light(2006) Dinçalp H.; Içli S.A new water-soluble perylene diimide derivative, N,N′-bis(12- sulfoaminododecyl)-3,4,9,10-perylenetetracarboxdiimide (SULFAPER), has been synthesized and characterized by visible, fluorescence, IR, 1H and 13C NMR, mass, CV and time resolved measurements. Its photophysical properties in aqueous and organic solutions have been described. The singlet energy levels of the synthesized compound have been found to be 57.8 kcal/mol and 59.2 kcal/mol in aqueous and methanol solution, respectively. The LUMO energy level of SULFAPER has been determined by solid state cyclic voltammetry, and found to be -3.60 eV. SULFAPER undergoes two electron reduction process (-0.64 V and -0.42 V) versus ferrocene. SULFAPER has an energy band gap of 2.56 eV. The absorption maximum of the synthesized compound gives bathochromic shift of 12 nm in water with respect to its visible spectrum in methanol solution. The fluorescence quantum yields of the compound are low both in water and methanol solution because of the aggregation effect. Time-resolved fluorescence measurements have showed that the fluorescence decay times of the SULFAPER are τ1 = 4.1 ns and τ2 = 0.8 ns in water, and τ1 = 4.0 ns and τ2 = 2.5 ns in methanol solutions. The aqueous solution of SULFAPER is stable under UV-VIS irradiation, but a slight loss of fluorescence emission (25%) has been detected at a rate of k p = 6.3 × 10-5 s-1 in methanol solution, which might be the result of either the quenching of fluorescence emission by reactive oxygen species, or by enhanced aggregation effect. SULFAPER-sensitized photooxidations of (E)-cinnamic acid and methyl acrylate have been found to give selective photoproduct formations under concentrated sun light in organic phase. (E)-cinnamic acid has been seen to favor photochemical E-Z isomerization and methyl acrylate has been seen to favor the formation of methyl 2-oxopropanoate. The quantum yield of (E)-cinnamic acid (ΦCA) under concentrated solar irradiation process has been calculated to be about 0.015, by the employment of an actinometry method developed by Erten and Icli. © 2005 Elsevier Ltd. All rights reserved.Item Preliminary tests of the radiopharmaceutical potential of N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)-perylene-3,4,9,10-tetracarboxylic diimide radiolabeled with 131 I(Springer Netherlands, 2007) Avcıbaşı U.; Dinçalp H.; Ünak T.; Yıldırım Y.; Avcibaşi N.; Duman Y.; Içli S.Perylene diimide denvatives are one of the G-quadruplex DNA interactive agents which are thought to be useful in application of cancer treatment Starting from this consideration, N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)- perylene-3,4,9,10-tetracarboxylic diimide (PYPER) was synthesized, radioiodinated with 131 I, and its radiopharmaceutical potentials were tested on a male Albino rabbit and male Albino Wistar rats. This compound was successfully radioiodinated with 131 I with a radioiodination yield of about 100%. Scintigraphic imaging with the radiiodinated compound ( 131 I-PYPER) was performed on a rabbit. Static images were obtained from posterior projection using a Diacan gamma camera at several time intervals. The scintigrams clearly showed that the radioiodinated compound was not quickly cleared from the metabolism, accumulating in the stomach over about 30 minutes. The clearance time of this compound was considerably longer than 5 hours. The results obtained in this study agreed with that of the biodistribution studies and indicated that 131 I-PYPER might be used as a scintigraphic agent for examining stomach diseases. © 2007 Springer Science+Business Media, Inc.Item Fluorescent macromolecular perylene diimides containing pyrene or indole units in bay positions(2010) Dinçalp H.; Kizilok S.; Içli S.Novel, symmetric and unsymmetric perylene diimide dyes with pyrene or indole units in the bay positions of the perylene ring were synthesized and characterized using FT-IR, 1H and 13C NMR, MS, UV-Vis spectra and cyclic voltammetry. The λmax in different solvents were in the range 526-585 nm and emission wavelengths of the dyes exhibited positive solvatochromism with increasing solvent polarity. Long wavelength emissions >750 nm of dyes with pyrene units displayed charge-separated state of perylene-pyrene system. Dyes with pyrene or indole units showed greater photostability in toluene than dyes which did not contain these bulky substituents. Incorporating electron-donating indole substituents lowered the band gap energies and, therefore, the HOMO energy levels were increased. The energy density and shape of the molecular orbitals were calculated theoretically. © 2009 Elsevier Ltd. All rights reserved.Item Optical and photovoltaic properties of salicylaldimine-based azo ligands(2010) Dinçalp H.; Yavuz S.; Hakli O.; Zafer C.; Özsoy C.; Durucasu I.; Içli S.A series of azo dyes containing salicylaldimine-based ligands as side chains were prepared and characterized. Absorption and emission data in five solvents of different polarities were studied. Photoirradiation studies under an oxygen atmosphere in water showed that the Schiff base side chains enhanced the photo-oxidative stability of the azo chromophore. The electrochemical properties of the dyes were investigated by a cyclic voltammetry. The synthesized salicylaldimine-based azo dyes gave two irreversible oxidation potentials. Complexation behavior of synthesized compounds with titanium (IV) ions was illustrated by the change in their absorption spectra. These ligands are appropriate sensitizers for anchoring to the TiO2 surface chemically in dye-sensitized solar cell (DSSC) productions. Electron injection capacities to TiO2 and photovoltaic performance of the synthesized salicylaldimine-based azo dyes were tested with DSSC. © 2009 Elsevier B.V. All rights reserved.Item Synthesis and spectroscopic properties of a novel perylenediimide derivative(2011) Hakli-Birel O.; Dinçalp H.; Zafer C.; Demiç S.; Colladet K.; Vanderzande D.; Yürüm Y.; Içli S.A novel symmetric 3,4,9,10-perylenetetracarboxylic acid derivative (PDI1) dye based on thiophene donor group was synthesized and characterized by FT-IR and 1H NMR. Cyclic Voltammetry analysis is performed to determine the energy levels of the perylene derivative. Optical characteristics were determined by visible absorption and fluorescence emission spectra. Spectral behavior and fluorescence quantum yield of PDI1 have been measured in different solvents. The dye exhibits high fluorescence quantum yield (Φf: 0.94-0.99). But the quantum yield PDI1 is very low in the n-butanol solution (Φf: 0.12). The photophysical properties have important implications for use in a variety of electroactive and photovoltaic applications. A photovoltaic device was fabricated with PDI1 as transporting material. The conversion efficiency for DSSC sensitized by PDI1 is 0.0065%. PDI1 exhibits electrochromic behavior by switching between neutral (red) and oxidized (blue) states. Electron transfer capacity of PDI to the TiO2 was investigated by incorporation of dye as sensitizer in dye sensitized solar cell (DSSC). Soluble dye molecules are very important toprepare dye sensitized solar cell. Solubility was increased with thiophene group.Item Synthesis and G-quadruplex binding study of a novel full visible absorbing perylene diimide dye(2012) Dinçalp H.; Kizilok Ş.; Birel O.H.; Içli S.A novel perylene diimide dye containing glucopyranosyl groups in 1- and 7-positions of the perylene ring has been synthesized and characterized to obtain highly efficient and stable photosensitized material in photodynamic therapy. Solvatochromic studies on this dye in solvents of different polarities have indicated that absorption bands of the dye cover the whole visible spectrum in more polar organic solvents. It shows absorption bands localized at 350-500 nm and 600-850 nm in benzonitrile giving a green color. Also, the dye has a wide absorption region which covers the wavelength between 400 and 800 nm in more polar solvents by changing the dye concentration in the solvents. Singlet oxygen generation efficiency and G-quadruplex binding affinity of the dye have been tested. Theoretical calculations through semi-empirical methods have been performed and a detailed spectroscopic assignment of the molecule has been also presented. © 2012 Elsevier B.V.Item Synthesis, characterization and optoelectronic properties of a new perylene diimide-benzimidazole type solar light harvesting dye(Elsevier, 2014) Dinçalp H.; Çimen O.; Ameri T.; Brabec C.J.; Içli S.A perylene diimide type small molecule (BI-PDI) has been synthesized through Suzuki coupling reaction between N,N′-bis(2,6-diisopropylphenyl)- 1,7-dibromoperylene-3,4,9,10-tetracarboxylic diimide and 2-(2-hydroxyphenyl)-7- phenyl-1H-benzimidazole-4-boronic acid. BI-PDI small molecule has showed an absorption band between 350 and 750 nm on thin films. HOMO and LUMO energy levels of BI-PDI dye have been calculated to be about -5.92 eV and -3.82 eV, respectively. Solution-processed bulk heterojunction (BHJ) solar cells have been constructed using BI-PDI as donor and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor or poly(3-hexylthiophene) (P3HT) as donor and BI-PDI as acceptor. The external quantum efficiencies (EQE) of the devices cover the most of the visible region between 400 and 700 nm for both configurations. Photovoltaic performances of BI-PDI-based organic solar cells are limited by the aggregation tendency of PDI structure and poor hole/electron mobilities of the active layer. © 2014 Elsevier B.V. All rights reserved.Item Improvement of intramolecular charge transfer within a donor-acceptor blend by doping novel synthesized benzothiadiazole small molecules in solid state(Elsevier B.V., 2014) Dinçalp H.; Murat G.; Içli S.Three electron-deficient small molecules based on 2,1,3-benzothiadiazole (BTD) units namely, 4,7-bis(3-methoxyphenyl)-2,1,3-benzothiadiazole (BT1), (3-{7-[3-(dimethylamino)phenyl]-2,1,3-benzothiadiazole-4-yl}phenyl) dimethylamine (BT2) and 3,3′-(2,1,3-benzothiadiazole-4,7-dyl)dianiline (BT3) were synthesized and their photophysical properties were investigated systematically to understand their potential usage in ternary organic solar cells (OSCs) as additive material to enhance the cell efficiency. All these molecules show broad absorption bands in 350-750 nm on glass substrate and their optical band gaps were calculated to be around 2.50-2.80 eV. BTD fluorescence dynamics were measured in polymer:BT1:fullerene blends with varying emission wavelengths of active layer. Fluorescence emission and time resolved measurements indicated photoinduced energy shift from BT1 dye to fullerene and also from polymer to BT1 dye upon excitation of the active layer. © 2014 Elsevier B.V. All rights reserved.Item Targeted singlet oxygen generation using different DNA-interacting perylene diimide type photosensitizers(Springer New York LLC, 2014) Dinçalp H.; KIzIlok Ş.; Içli S.Singlet oxygen quantum yields (ΦΔ) of different perylene diimides (PDIs) containing phenyl (PDI-Ph), pyrene (PDI-Pyr), and indole (PDI-In) units in bay positions of the ring were determined using 1,3-diphenylisobenzofuran (DPBF) method in toluene/methanol (99:1) system. Pyrene-substituted PDI were the most efficient singlet oxygen generator among the investigated photosensitizers with a quantum yield of Φ Δ=0.93 in toluene/methanol. Additionally, their binding affinities to G-quadruplex DNA structure were investigated by steady-state measurements. There were marked red shifts of absorbance bands for PDI-Pyr/DNA strand complexes with respect to the absorption maxima of DNA-free solution of PDI-Pyr in phosphate buffer at pH 6. © 2014 Springer Science+Business Media New York.