Browsing by Author "Bilgin, Suay"

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Aerobic oxidation of alcohols catalyzed by an efficient heterogeneous mixed metal hydroxide catalyst
(2024-08) Bilgin, Suay
Aerobic alcohol oxidation is one of the important reactions of organic chemistry used both in academic research and in many industries such as medicine, cosmetics and food. Aldehydes, carboxylic acids and ketones resulting from alcohol oxidation are encountered as intermediates or final products. However, some oxidation methods developed to date have drawbacks such as expensiveness, being hazardous to human health and the environment, and having low sustainability. For this reason, Fe0.6Mn0.4(OH)x mixed metal hydroxide catalyst was developed in a collaborative work by the Ozensoy and Türkmen research groups by avoiding these drawbacks and was first used in the C-H activation reaction giving successful results. In this project, alcohol oxidation reactions were carried out using the same catalyst. Optimized reaction conditions were found by the model reaction of conversion from benzhydrol to benzophenone. Then, substrates with different electron withdrawing and donating groups attached to benzhydrol were tested along with benzyl alcohol and 1-phenylethanol derivatives. Finally, an attempt was made to obtain information about the working mechanism of the catalyst by performing a kinetic isotope effect experiment and various control experiments.
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Na-promoted bimetallic hydroxide nanoparticles for aerobic c-h activation catalyst design principles and insights into reaction mechanism
(American Chemical Society, 2024-10-25) Erdivan, Beyzanur; Çalıkyılmaz, Eylül; Bilgin, Suay; Erdali, Ayşe Dilay; Gül, Damla Nur; Ercan, Kerem Emre; Türkmen, Yunus Emre; Özensoy, Emrah
A precious metal-free bimetallic Fe x Mn1-x (OH) y hydroxide catalyst was developed that is capable of catalyzing aerobic C-H oxidation reactions at low temperatures, without the need for an initiator, relying sustainably on molecular oxygen. Through a systematic synthetic effort, we scanned a wide nanoparticle synthesis parameter space to lay out a detailed set of catalyst design principles unraveling how the Fe/Mn cation ratio, NaOH(aq) concentration used in the synthesis, catalyst washing procedures, extent of residual Na+ promoters on the catalyst surface, reaction temperature, and catalyst loading influence catalytic C-H activation performance as a function of the electronic, surface chemical, and crystal structure of Fe x Mn1-x (OH) y bimetallic hydroxide nanostructures. Our comprehensive XRD, XPS, BET, ICP-MS, 1H NMR, and XANES structural/product characterization results as well as mechanistic kinetic isotope effect (KIE) studies provided the following valuable insights into the molecular level origins of the catalytic performance of the bimetallic Fe x Mn1-x (OH) y hydroxide nanostructures: (i) catalytic reactivity is due to the coexistence and synergistic operation of Fe3+ and Mn3+ cationic sites (with minor contributions from Fe2+ and Mn2+ sites) on the catalyst surface, where in the absence of one of these synergistic sites (i.e., in the presence of monometallic hydroxides), catalytic activity almost entirely vanishes, (ii) residual Na+ species on the catalyst surface act as efficient electronic promoters by increasing the electron density on the Fe3+ and Mn3+ cationic sites, which in turn, presumably enhance the electrophilic adsorption of organic reactants and strengthen the interaction between molecular oxygen and the catalyst surface, (iii) in the fluorene oxidation reaction the step dictating the reaction rate likely involved the breaking of a C-H bond (k H /k D = 2.4), (iv) reactivity patterns of a variety of alkylarene substrates indicate that the C-H bond cleavage follows a stepwise PT-ET (proton transfer-electron transfer) pathway.
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Türkiye'de Bahailik ve Bahai kültürü
(Bilkent University, 2019) Bilgin, Suay; Güzel, Furkan; Akyön, Burak; Kocaman, Arda; Laçin, Abdussamed
19. yüzyılın ikinci yarısında İran’da ortaya çıkan Bahai dini, peygamberi Hz. Bahaullah ve arkadaşları aracılığı ile zaman içinde tüm dünyaya yayılmıştır. Osmanlı İmparatorluğu da bulunduğu coğrafi konum itibariyle bu din ile tanışmış ve Bahai dini bu sayede toplumda kabul görmüştür. Bahai dininin Türkiye’de ve dünyada pek çok müridi bulunmaktadır. Bu çalışmada Bahai dini kültürel ögeleri, tarihi ve Bahai toplumu faaliyetleri anlatılmıştır. Bahai dini mensubu Semih Özşuca ile bir röportaj gerçekleştirilmiştir.