New phosphine-amino-alcohol tridentate ligands for ruthenium catalyzed asymmetric transfer hydrogenation of ketones

Altan, Orhan | Yılmaz, Mustafa Kemal

New phosphine-amino-alcohol tridentate ligands (3a-c) and six new ruthenium complexes (4a-c and 5a-c) were synthesized and characterized. Catalytic activities of the metal complexes were tested on aryl alkyl ketones. All of the substrates were converted to related sec-alcohols in excellent yields (up to 99%), but enantioselectivities were insufficient (up to 40% ee). Despite the catalytic performance of 5a-c complexes can be considered as better than 4a-c, actually the catalytic activity of the complexes has been differed according to substrate. The ketones with less positive carbonyl carbons tend to give S-configuration with 5a-c and R-configuration with 4a-c. The catalytic performance of the complexes was rationalized by means of DFT calculations.

Nanostructured Photocatalysts Chapter 15 - Black phosphorus-based photocatalysts for energy and environmental applications

Altan, Orhan

Photocatalysis using semiconductor materials to conduct chemical reactions more efficiently with the aid of sunlight irradiation is foreseen as a promising solution to combat the energy and environmental pollution crisis that the world is facing at present. Finding a suitable semiconductor material that harvests a large portion of the sunlight spectrum with high photocatalytic efficiency lies in the heart of photocatalysis. In this regard, black phosphorus (BP), a rising star two-dimensional (2D) semiconducting material, has recently been regarded as an abundant, nontoxic, metal-free, and cheap photocatalyst with a suitable bandgap and broad light absorption ability. In this chapter, after the introduction of the general properties and synthesis of BP, the photocatalytic efficiency of BP a...

Boosting formic acid dehydrogenation via the design of a Z-scheme heterojunction photocatalyst: The case of graphitic carbon nitride/Ag/Ag3PO4-AgPd quaternary nanocomposites

Altan, Orhan

The development of an efficient, eco-friendly, practical, and selective way to decompose formic acid (FA) into H2 and CO2 is crucial for the utilization of FA as a chemical hydrogen storage material in hydrogen economy. In this regard, photocatalytic FA dehydrogenation attracts great attention owing to its potential to meet the above-mentioned requirements. Interestingly, there is no example of heterojunction photocatalyst that tunes the hole potential of the semiconductor, resulted in a better photocatalytic activity. We report herein for the first time the design and fabrication of a novel Z-scheme heterojunction photocatalyst for FA dehydrogenation, denoted as g-CN/Ag/Ag3PO4-AgPd comprising graphitic carbon nitride (g-CN) and Ag3PO4 semiconductors, Ag and AgPd alloy nanoparticles (NPs)....

The influence of band bending phenomenon on photocatalytic Suzuki-Miyaura coupling reaction: The case of AgPd alloy nanoparticles supported on graphitic carbon nitride

Altan, Orhan

The development of solar-powered systems for applications other than energy, such as photocatalytic organic reactions, will benefit in the resolution of environmental issues while also lowering production costs. In this study, the photocatalytic activity of g-CN(G)-AgPd, which was prepared by synthesizing AgPd alloy nanoparticles (NPs) on g-CN, was investigated in the Suzuki-Miyaura coupling (SMC) reaction. The photocatalytic activity of g-CN(G)-AgPd in an ethanol/water mixture at ambient temperature was discovered to be among the highest ever recorded. Under vis-light illumination, g-CN(G)-AgPd converted all of the aryl iodides and most of the aryl bromides investigated to desired coupling products in 15 min with excellent isolated yields, and it was used at least five times without signi...

A rare example of the in situ formation of palladium nanoparticles: The emergence of catalytically active palladium nanoparticles from Pd (II) phosphine complexes in the Suzuki–Miyaura coupling reaction

Altan, Orhan

Suzuki–Miyaura coupling (SMC) reactions are one of the most promising routes for carbon–carbon bond formation. It is believed that metal complexes, particularly palladium complexes, are the most effective catalysts for this purpose. However, the catalysis nature whether it is homogenous or heterogeneous is under debate. It is commonly believed that a homogenous catalysis pathway is responsible for the catalytic activity when the phosphine ligands are present in the structure due to the strong phosphorus-metal interactions. In this study, Pd (II) complexes of phosphino-benzaldoxime ligands were synthesized, characterized, and tested in SMC reactions. Interestingly, it was found that the catalytic activity increased by 11 times when the amount of catalyst was reduced by 10-fold and increased...

The rational design of a graphitic carbon nitride-based dual S-scheme heterojunction with energy storage ability as a day/night photocatalyst for formic acid dehydrogenation

Altan, Orhan

Photocatalytic formic acid dehydrogenation (FAD) has been regarded as one of the most promising methods of producing H2 in a sustainable manner. In the photocatalytic FAD reaction, photogenerated holes play an important role in the reaction mechanism and thus in the efficiency of photocatalysts. However, the design of photocatalytic systems capable of generating high hole potential without compromising the reducing ability of the photocatalyst is extremely rare for the FAD reaction. In this respect, we report herein a novel and highly efficient heterojunction photocatalyst composed of 2D graphitic carbon nitride, 2D MnO2, 1D MnOOH, and 0D PdAg alloy nanoparticles, denoted as GCN/MnO2/MnOOH-PdAg, that can create high reduction and oxidation potentials via a dual S-scheme heterojunction. The...

Oreochromis niloticus'da kurşunun neden olduğu oksidatif strese karşı humik maddelerin koruyucu etkisinin araştırılması

Su, Zülfiye.

ÖZET Oreochromis niloticus’da Kurşunun Neden Olduğu Oksidatif Strese Karşı Humik Maddelerin Koruyucu Etkisinin Araştırılması Bu araştırmada, subletal kurşun (Pb) derişiminin Oreochromis niloticus’da antioksidan enzim sistemi üzerine etkilerine karşı, yeme katılan humik maddenin koruyuculuk özelliği incelenmiştir. Bu amaçla 1,5 mg/L kurşun nitrat Pb(NO3)2 ortam derişimi etkisinde bulunan balıklar, %0,2 oranında hümik madde katkısı bulunan yem ile beslenmişlerdir. Kontrol grubu, humik madde (HM), Pb, ve Pb+HM grublarını içeren bu çalışmada 4. ve 10. günlerde karaciğer örnekleri alınmıştır. Karaciğer dokusu katalaz (CAT) ve süperoksit dismutaz (SOD) enzim aktiviteleri ve lipid peroksidasyon ürünü olan malondealdehit (MDA) düzeyi, kontrol grubu ile karşılaştırıldığında, subletal kurşun derişim...

Fen bilgisi öğretmen adaylarında DNA replikasyonu ve protein sentezi ile ilgili kavram yanılgılarının belirlenmesi ve giderilmesi

Şahin, Tuğba

Optimum maliyet düzeyine göre enerji etkin konutların ısıl performansının araştırılması

Öktem, Hüseyin

Kontrollü kümelerde cebirsel işlemler

Gökalp, Emel

Güneş kollektörlerinin ultrasonik dikiş kaynağı ile birleştirilmesinde işlem parametrelerinin bağlantı kalitesine etkileri

Yeniyıl, Emre

İntuitionistic fuzzy model operatörlerin intuitionistic fuzzy yapılarla ilişkileri

Yılmaz, Sinem

Lamiaceae familyasına ait bazı bitkilerin uçucu yağ içeriklerinin belirlenmesi, antimikrobiyal ve antimutajenik aktivitelerinin araştırılması

Erdoğan, Elif Ayşe

Arşimedyan olmayan durumda Liouville sayılarının bazı karakterizasyonları

Aşan, Abdulkadir

Muz diliminin kuruma kinetiği

Demirel, Devlet

Mersin ve civarındaki beton yapılarında kullanılan agregaların alkali-agrega reaktivitesinin araştırılması

Öncel, Levent