WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Citation - WoS: 12Citation - Scopus: 11Trans-Cis Isomerization Assisted Synthesis of Solution-Processable Yellow Fluorescent Maleic Anhydrides for White-Light Generation(Elsevier Science SA, 2015-12) Ozdemir, Mehmet; Genc, Sinan; Ozdemir, Resul; Altintas, Yemliha; Citir, Murat; Sen, Unal; Usta, HakanHeterocyclic maleic anhydride derivatives have been extensively studied in natural products chemistry over the past few decades. However, their incorporation into optoelectronic devices has lagged behind that of other pi-conjugated systems, and they have never been studied in white light emitting diodes (WLEDs). The development of emissive pi-conjugated materials for (WLEDs) has been an emerging scientific and technological research area to replace phosphors used in LED-based solid-state lighting. Here, we demonstrate the design, synthesis and characterization of two new highly emissive alkyl-substituted bis(thienyl)maleic anhydrides (C6-Th2MA and C12-Th2MA) with favorable photophysical properties. The new core is synthesized via a novel trans-to-cis isomerization-assisted one-pot reaction, which is demonstrated for the first time in the literature for the synthesis of a bis(heteroaryl)maleic anhydride. Due to its favorable absorption and fluorescence properties in the blue and yellow region of the visible spectrum, respectively, C12-Th2MA is studied as a potential wavelength-upconverting material. A WLED fabricated by drop-casting a polymeric solution of C12-Th2MA on a blue LED (InGaN, 455 nm) yields promising CIE coordinates and color-rendering index (CRI) values of (0.24, 0.20) and 65.0, respectively. Considering the simplicity of the current molecular structure and facile synthesis, alkyl-substituted bis(thienyl)maleic anhydrides stand as ideal phosphor alternatives. Therefore, the current findings may open new perspectives for the development of maleic anhydride-based small molecules for low-cost, energy-efficient, and solution-processed lighting technologies. (C) 2015 Elsevier B.V. All rights reserved.Conference Object Thin Films of Inert Metal Nanowires for Display Applications(Tanger Ltd, 2015) Citir, Murat; Sen, Unal; Usta, Hakan; Canlier, Ali; Hakan, Usta; Ali, Canlier; Murat, Citir; Unal, SenAg nanowire transparent electrode has excellent transmittance (90%) and sheet resistance (20 Ohm/sq), yet there are slight drawbacks such as optical haze and chemical instability against aerial oxidation. Chemical stability of Ag nanowires needs to be improved in order for it to be suitable for electrode applications. Coating Ag nanowires with a thin layer of inert metals such as Au and Pd through galvanic exchange reactions may enhance the chemical stability of Ag nanowire films highly and also helps to obtain lower haze. In this study, coating of thin Au and Pd layers has been applied successfully onto the surface of Ag nanowires. Usually coatings are carried out by salts such as HAuCl4 and K2PdCl4 in order to make nanotubes. In this study, novel ethylenediamine(en) complexes of inert metal cations with mild oxidation power were prepared in order to oxidize Ag atoms partially on the surface through galvanic displacement. The mild galvanic exchange allowed for a thin layer (1-4 nm) of inert metal coating on the Ag nanowires with minimal truncation of the nanowire, where the average lengths and the diameters were between 10 similar to 14 mu m and 55 similar to 65 nm, respectively. The crystalline structure of the shell was formed epitaxially on the surface. The new Ag nanowires were suspended in methanol and then electrostatically sprayed on glass and flexible substrates. It was revealed that average total transmittance remain around 90% within visible spectrum region (400-800 nm) whereas sheet resistance rises up to 175 Ohm/sq. Very thin layer of inert metal costs low, though this may render an excellent catalyst for applications such as fuel cell and organic synthesis, whereas transparent films of inert metal-coated Ag nanowire can be utilized as working electrodes for spectro-electrochemical cells as well.Conference Object Selective Dye Uptake From Aqueous Industrial Waste Mixtures by Novel Covalent Organic Frameworks(Amer Chemical Soc, 2015) Filikci, Semra; Ulasan, Mehmet; Citir, Murat; Yavuz, MustafaConference Object Removal of Organic Solvents From Aqueous Waste Mixtures by Novel Covalent Organic Frameworks(Amer Chemical Soc, 2015) Ulasan, Mehmet; Filikci, Semra; Citir, Murat; Yavuz, MustafaArticle Citation - WoS: 104Citation - Scopus: 109Proton Conducting Poly(Vinyl Alcohol) (PVA)/Poly (2-Acrylamido Sulfonic Acid) (PAMPS)/Zeolitic Imidazolate Framework (ZIF) Ternary Composite Membrane(Elsevier, 2016-02) Erkartal, Mustafa; Usta, Hakan; Citir, Murat; Sen, UnalThe design, synthesis and characterization of novel proton exchange membranes (PEMs) are of significant scientific and technological importance for the realization of fuel cells, actuators, and sensors. Here, we demonstrate a novel ternary composite membrane consisting of poly(vinyl alcohol) (PVA), poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS), zeolitic imidazolate framework-8 (ZIF-8), which is prepared by physical blending and casting methods. To enhance the water management of the membranes, in situ chemical cross-linking is carried out by glutaraldehyde (GA). During the characterization of the new membranes, FT-IR is used for intermolecular and inter-polymer interactions between different components of the membrane, SEM is used to identify morphology, XRD is used to prove the presence of ZIF-8 nanoparticles, and finally TGA is used for thermal stability. The proton conductivity of the membranes is found to increase with temperature and also with the increasing content of PAMPS. The highest proton conductivity under fully hydrated state at 80 degrees C is measured as 0.134 S cm(-1) for PVA: PAMPS: ZIF-8 (55:40:5) composition. In this study, it is clearly shown that ZIF-8 nanoparticles contribute to the proton conductivity by forming hydrogen bonds with the polymer network in the membrane. The water uptake (WU) and ion exchange capacity (IEC) values are 3.28 (gig) and 1.52 meq g(-1), respectively for the same membrane. To the best our knowledge, this study shows one of the first example of a MOFcontaining membrane with truly high proton conductivities, and both values of proton conductivity and electrochemical properties are comparable to those of well-studied membrane, Nation. (C) 2015 Elsevier B.V. All rights reserved.Conference Object New Method for Measuring the Temperature Change of Photothermal Au Nanostructures Using Smart Polymers(Amer Chemical Soc, 2015) Cavusoglu, Halit; Sakalak, Huseyin; Buyukbekar, Burak Zafer; Demirel, Gokhan; Citir, Murat; Yavuz, Mustafa SelmanConference Object Nanothermometer: Measuring Temperature Change in Nanometer Scale on Photothermal Au Nanoparticles(Amer Chemical Soc, 2015) Sakalak, Huseyin; Cavusoglu, Halit; Buyukbekar, Burak Zafer; Demirel, Gokhan; Citir, Murat; Yavuz, Mustafa SelmanConference Object Measuring Temperature Change on Photothermal Au Nanorod and Nanocage Upon Laser Irradiation(Amer Chemical Soc, 2015) Cavusoglu, Halit; Sakalak, Huseyin; Buyukbekar, Burak Zafer; Demirel, Gokhan; Citir, Murat; Yavuz, Mustafa SelmanArticle Citation - WoS: 6Citation - Scopus: 7Measuring Temperature Change at the Nanometer Scale on Gold Nanoparticles by Using Thermoresponsive PEGMA Polymers(Wiley-VCH Verlag GmbH, 2017-06-13) Yavuz, Mustafa S.; Citir, Murat; Cavusoglu, Halit; Demirel, GokhanPlasmonic heating of gold nanoparticles (AuNPs) under laser illumination is a highly desirable technique, especially for cancer therapy. However, significant drawbacks still remain including uncontrolled heat release from AuNPs, random exposure duration, and selection of the proper laser power without damaging normal healthy cells. Herein, we demonstrate a simple and versatile method to measure temperature variation on the surface of Au nanoparticles under laser irradiation based on a thermoresponsive polymer, poly(ethylene glycol) methylether methacrylate (PEGMA). In this context, a series of PEGMA polymers were synthesized to have different lower critical solution temperature (LCST) values (28-90 degrees C) and conjugated to the surface of spherical AuNPs by a gold-thiolate linkage. According to our strategy, the AuNPs first photothermally absorb light energy and convert it to heat owing to their tailored photothermal characteristics. The generated heat from the AuNPs subsequently dissipates into the surrounding thermoresponsive PEGMA polymer. When the temperature generated on the Au surface upon laser irradiation for a certain exposure time reaches the LCST value of the surrounding PEGMA polymer, the polymer chain collapses. Therefore, the hydrodynamic diameter of the PEGMA-coated AuNPs changes, which can be easily monitored by using dynamic light scattering (DLS). We systematically measured the temperature (28-90 degrees C) generated on the AuNP surfaces by using different laser power densities with varying durations. We believe that the resulting strategy will be very valuable for oncologists to easily predict the minimum laser power and duration needed to destroy the cancer cells through the photothermal effect of Au nanostructures.Article Citation - WoS: 18Citation - Scopus: 19Infrared Multiple Photon Dissociation Spectroscopy of Protonated Histidine and 4-Phenylmidazole(Elsevier, 2012-12) Citir, Murat; Hinton, Christopher S.; Oomens, Jos; Steill, Jeffrey D.; Armentrout, P. B.The gas-phase structures of protonated histidine (His) and the side-chain model, protonated 4-phenyl imidazole (PhIm), are examined by infrared multiple photon dissociation (IRMPD) action spectroscopy utilizing light generated by the free electron laser FELIX. To identify the structures present in the experimental studies, the measured IRMPD spectra are compared to spectra calculated at a B3LYP/6-311+G(d,p) level of theory. Relative energies of various conformers are provided by single point energy calculations carried out at the B3LYP, B3P86, and MP2(full) levels using the 6-311+G(2d,2p) basis set. On the basis of these experiments and calculations, the IRMPD action spectrum for H+(His) is characterized by a mixture of [N-pi,N-alpha] and [N-pi,CO] conformers, with the former dominating. These conformers have the protonated nitrogen atom of imidazole adjacent to the side-chain (N-pi) hydrogen bonding to the backbone amino nitrogen (N-alpha) and to the backbone carbonyl oxygen, respectively. Comparison of the present results to recent IRMPD studies of protonated histamine, the radical His(center dot+) cation, H+(HisArg), H-2(2+)(HisArg), and M+(His), where M+ = Li+, Na+, K+, Rb+, and Cs+, allows evaluation of the vibrational motions associated with the observed bands. (c) 2012 Elsevier B.V. All rights reserved.