Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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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.Article Citation - Scopus: 30Thermochemistry of Alkali Metal Cation Interactions With Histidine: Influence of the Side Chain(2012-11-26) Armentrout, Peter B.; Citir, Murat; Chen, Yu; Rodgers, Mary T.The interactions of alkali metal cations (M+ = Na+, K+, Rb+, Cs+) with the amino acid histidine (His) are examined in detail. Experimentally, bond energies are determined using threshold collision-induced dissociation of the M+(His) complexes with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy dependent cross sections provide 0 K bond energies of 2.31 ± 0.11, 1.70 ± 0.08, 1.42 ± 0.06, and 1.22 ± 0.06 eV for complexes of His with Na+, K+, Rb+, and Cs+, respectively. All bond dissociation energy (BDE) determinations include consideration of unimolecular decay rates, internal energy of reactant ions, and multiple ion-neutral collisions. These experimental results are compared to values obtained from quantum chemical calculations conducted previously at the MP2(full)/6-311+G(2d,2p), B3LYP/6-311+G(2d,2p), and B3P86/6-311+G(2d,2p) levels with geometries and zero point energies calculated at the B3LYP/6-311+G(d,p) level where Rb and Cs use the Hay-Wadt effective core potential and basis set augmented with additional polarization functions (HW*). Additional calculations using the def2-TZVPPD basis set with B3LYP geometries were conducted here at all three levels of theory. Either basis set yields similar results for Na+(His) and K+(His), which are in reasonable agreement with the experimental BDEs. For Rb+(His) and Cs +(His), the HW* basis set and ECP underestimate the experimental BDEs, whereas the def2-TZVPPD basis set yields results in good agreement. The effect of the imidazole side chain on the BDEs is examined by comparing the present results with previous thermochemistry for other amino acids. Both polarizability and the local dipole moment of the side chain are influential in the energetics. © 2012 American Chemical Society. © 2013 Elsevier B.V., All rights reserved.; MEDLINE® is the source for the MeSH terms of this document.Article Citation - WoS: 26Citation - Scopus: 27Selective Removal of Cationic Micro-Pollutants Using Disulfide-Linked Network Structures(Royal Soc Chemistry, 2017) Atas, Mehmet Sahin; Dursun, Sami; Akyildiz, Hasan; Citir, Murat; Yavuz, Cafer T.; Yavuz, Mustafa SelmanMicropollutants are found in all water sources, even after thorough treatments that include membrane filtration. New ones emerge as complex molecules are continuously produced and discarded after used. Treatment methods and sorbent designs are mainly based on non-specific interactions and, therefore, have been elusive. Here, we developed swellable covalent organic polymers (COP) with great affinity towards micropollutants, such as textile industry dyes. Surprisingly, only cationic dyes in aqueous solution were selectively and completely removed. Studies of the COPs surfaces led to a gating capture, where negatively charged layer attracts cationic dyes and moves them inside the swollen gel through diffusive and hydrophobic interaction of the hydrocarbon fragments. Despite its larger molecular size, crystal violet has been taken the most, 13.4 mg g(-1), surpassing all competing sorbents. The maximum adsorption capacity increased from 12.4 to 14.6 mg and from 8.9 to 11.4 mg when the temperature of dye solution was increased from 20 to 70 degrees C. The results indicated that disulfide-linked COPs are attractive candidates for selectively eliminating cationic dyes from industrial wastewater due to exceptional swelling behaviour, low-cost and easy synthesis.Article 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: 1Citation - Scopus: 1Highly Efficient Chlorinated Solvent Uptake by Novel Covalent Organic Networks via Thiol-Ene Chemistry(Springer, 2021-07-03) Yavuz, Mustafa Selman; Citir, MuratIn this study, we synthesized an aliphatic-aromatic regular network as a novel covalent organic networks called TEPN-1 (Thiol-ene Polymer Network) and TEPN-2 via thiol-ene chemistry. TEPN-1 and TEPN-2 were analyzed by FTIR, C-13-NMR, Brunauer-Emmett-Teller, thermogravimetric analysis and elemental analysis. Solvent uptake capacity of TEPN-1 and TEPN-2 was employed against 26 solvents which are frequently used in chemical industry. It is found that TEPN-1 has the highest swelling adsorption ratio with chloroform and DCM (13.7 and 11.5 g.g(-1), respectively), while TEPN-2 has 9.2 and 7.5 g.g(-1), respectively. Both TEPN-1 and TEPN-2 have very minimal water uptake (0.165 and 0.189 g.g(-1), respectively). TEPN-1 and TEPN-2 are efficient adsorbents for most of organic solvents including water-miscible organic solvents such as THF, dioxane and pyridine.Article Citation - WoS: 58Citation - Scopus: 59Bond Energies of ThO+ and ThC+: A Guided Ion Beam and Quantum Chemical Investigation of the Reactions of Thorium Cation With O2 and CO(AIP Publishing, 2016-05-13) Cox, Richard M.; Citir, Murat; Armentrout, P. B.; Battey, Samuel R.; Peterson, Kirk A.Kinetic energy dependent reactions of Th+ with O-2 and CO are studied using a guided ion beam tandem mass spectrometer. The formation of ThO+ in the reaction of Th+ with O-2 is observed to be exothermic and barrierless with a reaction efficiency at low energies of k/k(LGS) = 1.21 +/- 0.24 similar to the efficiency observed in ion cyclotron resonance experiments. Formation of ThO+ and ThC+ in the reaction of Th+ with CO is endothermic in both cases. The kinetic energy dependent cross sections for formation of these product ions were evaluated to determine 0 K bond dissociation energies (BDEs) of D-0(Th+-O) = 8.57 +/- 0.14 eV and D-0(Th+-C) = 4.82 +/- 0.29 eV. The present value of D-0(Th+-O) is within experimental uncertainty of previously reported experimental values, whereas this is the first report of D-0(Th+-C). Both BDEs are observed to be larger than those of their transition metal congeners, TiL+, ZrL+, and HfL+ (L = O and C), believed to be a result of lanthanide contraction. Additionally, the reactions were explored by quantum chemical calculations, including a full Feller-Peterson-Dixon composite approach with correlation contributions up to coupled-cluster singles and doubles with iterative triples and quadruples (CCSDTQ) for ThC, ThC+, ThO, and ThO+, as well as more approximate CCSD with perturbative (triples) [CCSD(T)] calculations where a semi-empirical model was used to estimate spin-orbit energy contributions. Finally, the ThO+ BDE is compared to other actinide (An) oxide cation BDEs and a simple model utilizing An(+) promotion energies to the reactive state is used to estimate AnO(+) and AnC(+) BDEs. For AnO(+), this model yields predictions that are typically within experimental uncertainty and performs better than density functional theory calculations presented previously. Published by AIP Publishing.Article Citation - Scopus: 50Activation of Methane by Os+: Guided-Ion and Theoretical Studies(2013-08-19) Armentrout, Peter B.; Parke, Laura G.; Hinton, Christopher S.; Citir, MuratActivation of methane by the third-row transition-metal cation Os + is studied experimentally by examining the kinetic energy dependence of reactions of Os+ with CH<inf>4</inf> and CD<inf>4</inf> using guided-ion-beam tandem mass spectrometry. A flow tube ion source produces Os+ in its electronic ground state and primarily in the ground spin-orbit level. Dehydrogenation to form [Os,C,2 H]++H<inf>2</inf> is exothermic, efficient, and the only process observed at low energies for reaction of Os+ with methane, whereas OsH+ dominates the product spectrum at higher energies. The kinetic energy dependences of the cross sections for several endothermic reactions are analyzed to give 0K bond dissociation energies (in eV) of D<inf>0</inf>(Os+-C)=6.20±0. 21, D<inf>0</inf>(Os+-CH)=6.77±0.15, and D<inf>0</inf>(Os +-CH<inf>3</inf>)=3.00±0.17. Because it is formed exothermically, D<inf>0</inf>(Os+-CH<inf>2</inf>) must be greater than 4.71eV, and a speculative interpretation suggests the exothermicity exceeds 0.6eV. Quantum chemical calculations at the B3LYP/def2-TZVPP level show reasonable agreement with the experimental bond energies and with previous theoretical values available. Theory also provides the electronic structures of the product species as well as intermediates and transition states along the reactive potential energy surfaces. Notably, the structure of the dehydrogenation product is predicted to be HOsCH+, rather than OsCH<inf>2</inf>+, in contrast to previous work. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. © 2013 Elsevier B.V., All rights reserved.