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Öğe Boron containing chiral Schiff bases: Synthesis and catalytic activity in asymmetric transfer hydrogenation (ATH) of ketones(Elsevier, 2020) Pasa, Salih; Arslan, Nevin; Meric, Nermin; Kayan, Cezmi; Bingul, Murat; Durap, Feyyaz; Aydemir, MuratAsymmetric Transfer Hydrogenation (ATH) has been an attractive way for the reduction of ketones to chiral alcohols. A great number of novel and valuable synthetic pathways have been achived by the combination usage of organometallic and coordination chemistry for the production of important class of compounds and particularly optically active molecules. For this aim, four boron containing Schiff bases were synthesized by the reaction of 4-formylphenylboronic acid with chiral amines. The boron containing structures have been found as stable compounds due to the presence of covalent B-O bonds and thus could be handled in laboratory environment. They were characterized by H-1 NMR and FT-IR spectroscopy and elemental analysis and they were used as catalyst in the transfer hydrogenation of ketones to the related alcohol derivatives with high conversions (up to 99%) and low enantioselectivities (up to 22% ee). (C) 2019 Elsevier B.V. All rights reserved.Öğe Catalysts for the asymmetric transfer hydrogenation of various ketones from [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] and [Ru(?6-arene)(?-Cl)Cl]2, Ir(?5-C5Me5)(?-Cl)Cl]2 or [Rh(?-Cl)(cod)]2(Elsevier Science Sa, 2019) Meric, Nermin; Arslan, Nevin; Kayan, Cezmi; Rafikov, Khadichakhan; Zazybin, Alexey; Kerimkulova, Aygul; Aydemir, MuratThe combination of [3-[(2S)-2-[(diphenylphosphanyl)oxy]-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride] with [Ru(eta(6)-arene)(mu-Cl)Cl](2), Ir(eta(5)-C5Me5)(mu-Cl)Cl](2) or [Rh(mu-Cl)(cod)](2), in the presence of KOH/isoPrOH, has been found to generate catalysts that are capable of enantioselectively reducing alkyl, aryl ketones to the corresponding (R)-alcohols. Under optimized conditions, when the catalysts were applied to the asymmetric transfer hydrogenation, we obtained the secondary alcohol products in high conversions and enantioselectivities using only 0.5 mol% catalyst loading. In addition, [3-[(2S)-2-{[(chloro(eta(4)-1,5-cyclooctadiene)rhodium)diphenyl phosphanyl] oxy}-3-phenoxypropyl]-1-methyl-1H-imidazol-3-ium chloride], (6) complex is much more active than the other analogous complexes in the transfer hydrogenation. Catalyst 6 acts as excellent catalysts, giving the corresponding (R)-1-phenyl ethanol in 99% conversion in 30 min (TOF <= 396 h(-1)) and in high enantioselectivity (92% ee).Öğe Effect of initial configuration on DFT calculations for transition metal complexes(Osman SAĞDIÇ, 2019) Binbay, Nil E.; Binbay, Veysel; Aydemir, Murat; Durap, Feyyaz; Meriç, Nermin; Kayan, Cezmi; Arslan, NevinComputational methods, which solves the Schrödinger’s equation for molecules, have become an indispensable tool in last decades.And Density Functional Theory is one of the most used, and most effective computational method.Transition Metal complexes, on the other hand, have been being used extensively in many important applications in many fields, suchas chemical catalysts, atomic thin films, and pharmaceutical industry. Applying computational methods to transition metal complexeshas become inevitable to understand better, to control and to design these compounds.As it is known, it is very difficult to handle transition metals computationally, mostly due to near degeneracy in their electronic states.The computational algorithms usually cannot achieve as successive result as they can do for other typical elements, like carbon ornitrogen for instance. Computational methods are needed to be improved for properly deal with transition metal complexes. To findcomputationally cheaper but still effective methods to deal with these complexes is a major challenge.Unlike the analogue calculations, computational methods solve all equations iteratively, so there are major differences between thesetwo calculation types. The starting point in state space (the assumed initial conformation of molecule) is could have a stronger effectthen the expected, on the flow of the iterative solving algorithm of the computational approach.Here we present a comparative study for a Ruthenium complex. We have optimised the molecule several times. Each of the optimisationsstarted from different initial molecular conformations. Then we have compared the result in different ways, like calculation times andminimum energy that had reached, to see effect of starting configurations on the calculation.It is showed that, starting configuration is an important parameter for computational calculations of transition metal complexes, and itis needed to be carefully chosen to improve success of calculations.Öğe Electrical and photoelectrical characterization of organic-inorganic heterostructures based on Ru-N-heterocyclic carbene complexes(Elsevier Gmbh, 2018) Yasar, Sedat; Cekirdek, Suzan; Binbay, Nil Ertekin; Tombak, Ahmet; Ocak, Yusuf Selim; Arslan, Nevin; Baysal, Akin1,3-Bis(2-morpholinethyl)benzimidazoliumtrichlorido(eta(6)-p-cymene)-ruthenate(11), 2, was synthesized and characterized by NMR spectroscopy and micro analysis. The organic -inorganic heterojunctions were fabricated by using n-type Si wafer and a series of Ru-N-heterocyclic carbene complexes, 3-5, bearing sterically hindered aryl groups were documented for the first time. The thin films of the complexes are deposited on n-Si substrates using spin coating. Current-voltage (I-V) measurements of the devices in dark and illuminated environments were analyzed to determine electrical parameters of devices. Furthermore, the photoelectrical properties of the structures were investigated examined using I-V measurements under a solar simulator. Complexes 3 and 5 showed very low series resistance resulting in high rectification ratios which are promising results for the future electronic and photoelectronic applications. (C) 2017 Published by Elsevier GmbH.Öğe Esteraz modeli olarak yeni bir kiral miselin dizaynı(2017) Arslan, Nevin; Pirinççioğlu, NecmettinEnzim katalizi, kovalent olmayan etkileşimler, host katalizli reaksiyonların kinetiği ve supramoleküler kompleks oluşumlu kataliz reaksiyonları tartışıldı. (R)-2-amino-1-bütanolden çıkarak kiral bir misel olan Dodesil (1-hidroksimetil-propil) dimetil amonyum bromür sentezlendi. Bu misellin, hazırlanan enantiyomerce saf (R) ve (S) p-nitrofenil-3-fenilbütanoatın hidrolizinde katalitik etkisi incelendi. Miselin S enantiyomerini R’den daha iyi katalizlediği ve bunun %30 ee’ye takabül edildiği görüldü.Öğe Experimental and theoretical study of the mechanism of hydrolysis of substituted phenyl hexanoates catalysed by globin in the presence of surfactant(Springer, 2014) Ercan, Selami; Arslan, Nevin; Kocakaya, Safak Ozhan; Pirinccioglu, Necmettin; Williams, AndrewThe bimolecular rate constants for the globin-and alkali-catalysed hydrolysis of substituted phenyl hexanoates in the absence and presence of cetyltrimethylammonium bromide (CTAB) obey Bronsted equations with beta(1g)=-0.53 (globin-catalysed), -0.68 (globin-catalysed in CTAB), -0.34 (in water) and -0.74 (in CTAB), respectively. The slopes indicate that the microsolvation environments associated with the transition states of the catalysed reactions are different from those that occur in aqueous medium. The slope (-0.74) for the reaction in CTAB implies that it proceeds in a less polar medium. The larger beta(1g) value (-0.53) obtained for the globin-catalysed reaction compared to that for the uncatalysed one may be attributed to either the less polar microenvironments of the transition states or the involvement of one of the imidazole groups as a nucleophile. The results from a study of the effect of pH on the reactivity provide evidence for the latter assumption. All of the ligands were docked into the hydrophobic pocket of the protein, and the resulting docking scores ranged from -30.76 to -23.61 kcal mol(-1). Molecular dynamic simulations and MM-PBSA/GBSA calculations performed for the complexes gave insight into the binding modes of globin to the esters, which are consistent with experimental results. The calculations yielded comparable free energies of binding to the experimental ones for 4-nitrophenyl and 4-chloro-2-nitrophenyl hexanoates. In conclusion, information obtained from the linear free-energy relationship is still very useful for elucidating the mechanisms of organic reactions, including enzyme-catalysed reactions. This approach is further supported by the utilization of computational tools.Öğe ?-Hydroxyamide derivatives of salicylic acid as organocatalysts for enantioselective reductions of prochiral ketones(Pergamon-Elsevier Science Ltd, 2013) Turgut, Yilmaz; Azizoglu, Murat; Erdogan, Asli; Arslan, Nevin; Hosgoren, HalilIn order to find the most effective catalyst for the enantioselective reduction of a prochiral ketone, a series of novel beta-hydroxyamide derivatives of salicylic acid and chiral amino alcohols were synthesized. Different substituted prochiral ketones have been reduced in high yield (up to 99%) and the corresponding secondary alcohols are formed with good enantiomeric excess (up to 86%). The mechanism of this type of catalyst can be explained by considering the reaction mechanism for the CBS catalyst. (C) 2013 Elsevier Ltd. All rights reserved.Öğe Pirolin temelli kiral organokatalistlerin sentezi ve bunların aldol reaksiyonlarındaki asimetrik indüksiyon etkilerinin araştırılması: Deneysel ve teorik bir yaklaşım(2015) Arslan, NevinOptikçe aktif bileşikler ilgili çalışmalar endüstriyel ve akademik alanda çok önemli bir yer tutar. Asimetrik kataliz optikçe aktif bileşiklerin sentezi için ideal bir yöntem olarak kabul edilebilir. Stereokimyada asimterik indüksiyon, sübstrat, reaktif, katalist veya çevredeki kiral bir özelliğinin etkisi sonucu bir enantiyomer veya diyastreoizomerden birinin seçici oluşumu olarak tanımlanır. Asimetrik indüksiyon asimetrik sentezde temel bir olgu olarak yer almakta olup ilk kez Emil Fischer tarafından karbohidratlar üzerindeki çalışmalarıyla literatüre girmiştir. Bu alanda yapılan çalışmalar genellikle metal içeren kiral ligantlar içermektedir. Konunun önemi 2001 Nobel Kimya ödülüyle taçlandırılmıştır. Bu çalışmada C2 simetrisine sahip prolin temelli 4 adet organokatalizörler sentezlendi ve yapıları aydınlatıldı. Elde edilen 4 adet organokatalizörlerin Aldol tepkimelerindeki asimetrik indüksiyon etkileri araştırıldı. Deneysel çalışmalara başlamadan önce sentezlenecek ligantların hangi tür Adol reaksiyonu için etkili olabileceği teorik olarak çalışıldı ve alınan sonuçlar doğrultusunda reaksiyonlar seçildi. Elde edelin sonuçlar teorik olanlarla kıyaslandı. Bu hesaplamalar için katalistlerin moleküler dinamik dvaranışları için amber9 kullanılırken bu katalistlerin katalizledikleri reaksiyonlar için temel, geçiş ve ürün halleri içinse Gaussian 03 paket programı kullanılarak hesaplamalar b3lyp/6-31+g(d) seviyesinde yapıldı. Anahtar Kelimeler pirolin,asimetrik indüksiyon,organokatalist, moleküler modellemeÖğe Proline-based organocatalyst-mediated asymmetric aldol reaction of acetone with substituted aromatic aldehydes: An experimental and theoretical study(TUBITAK, 2020) Arslan, Nevin; Ercan, Selami; Pirinççi̇oğlu, NecmettinThis work involves a facile synthesis of three (S)-proline-based organocatalysts with C2 symmetry and their effects in enantioselective aldol reaction of acetone with substituted aromatic aldehydes. Moderate enantioselectivities (up to 61% ee) were obtained depending on the nature of the substituents on the aryl ring. Computational calculations at HF/6-31 + G(d) level were employed to underline the enantioselectivity imposed by all the organocatalysts. Higher calculations at B3LYP/6-311 ++ G(d,p) scrf=(solvent=dichloromethane)//B3LYP/6-31 + G(d) levels of theory were also performed for the aldol reaction of acetone with benzaldehyde and 4-nitrobenzaldehyde catalyzed by 1. The computational outcomes were consistent with those produced by experimental results and they were valuable to elucidate the mechanism for the observed stereoselectivity.Öğe A series of novel ?-hydroxyamide based catalysts for borane-mediated enantioselective reductions of prochiral ketones(Pergamon-Elsevier Science Ltd, 2016) Azizoglu, Murat; Erdogan, Asli; Arslan, Nevin; Turgut, Yilmaz; Hosgoren, Halil; Pirinccioglu, NecmettinThe enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand has received considerable attention. Hydroxylamine-based chiral ligands with amide and hydroxyl functions in the presence of other co-ordinating groups are highly effective in these asymmetric reductions. The current work presents a simple one step synthesis of a series of beta-hydroxyamide-based ligands from the reaction between 3-hydroxy-2-naphthoic acid and chiral amino alcohols and their applications as catalysts in asymmetric borane-mediated reductions of aromatic prochiral ketones in THE The reductions provided the corresponding secondary alcohols with up to 96% ee and in good to excellent yields (89-99%). OFF calculations at B3LYP/6-31+g(d) level offered theoretical models to account for the enantioselectivity imposed by the chiral ligands in the reductions of the ketones. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Synthesis of cis-1,2-diol-type chiral ligands and their dioxaborinane derivatives: Application for the asymmetric transfer hydrogenation of various ketones and biological evaluation(Wiley, 2020) Kılıç, Ahmet; Balcı, Tuğba Ersayan; Arslan, Nevin; Aydemir, Murat; Durap, Feyyaz; Okumuş, Veysi; Tekin, Recep; 0000-0001-9073-4339; 0000-0003-0899-1948; 0000-0002-4238-5012; 0000-0003-0142-9215; 0000-0002-5505-2700; 0000-0003-4577-4475Two cis-1,2-diol-type chiral ligands (T-1 and T-2) and their tri-coordinated chiral dioxaborinane (T(1-2)B(1-2)) and four-coordinated chiral dioxaborinane adducts with 4-tert-butyl pyridine sustained by N -> B dative bonds (T(1-2)B(1-2)-N) were synthesized and characterized by various spectroscopic techniques such as NMR (H-1, C-13, and B-11), FT-IR and UV-Vis spectroscopy, LC-MS/MS, and elemental analysis. It was suggested that both ferrocene and trifluoromethyl groups played key roles in the catalytic and biological studies because they could tune the solubility of the chiral dioxaborinane complexes and adjust the strength of intermolecular interactions. To assess the biological activities of newly synthesized chiral dioxaborinane compounds, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging, reducing power, antibacterial, DNA binding, and DNA cleavage activities were tested. Then, all chiral dioxaborinane complexes were investigated as catalysts for the asymmetric transfer hydrogenation of various ketones under suitable conditions. The results indicated that the chiral dioxaborinane catalysts performed well with high yields.Öğe Synthesis of rigid and C2-symmetric pyridino-15-crown-5 type macrocycles bearing diamide-diester functions: enantiomeric recognition for chiral primary organoammonium perchlorate salts(Pergamon-Elsevier Science Ltd, 2014) Seker, Sevil; Baris, Deniz; Arslan, Nevin; Turgut, Yilmaz; Pirinccioglu, Necmettin; Togrul, MahmutFour novel C-2-symmetric macrocyclic compounds with a pyridine function and possessing amide and ester lingeages were prepared. The enantiomeric discrimination abilities of these macrocycles against alpha-phenylethylammonium and alpha-(1-naphthyl)ethylammonium perchlorate salts were measured by standard H-1 NMR titration techniques in DMSO-d(6). A binding constant ratio of 31 (Kbind(S)/Kbind(R)) for two enantiomers of alpha-(1-naphthyl)ethylammonium salt with the macrocyclic host (S,S)-4 bearing phenyl arms was observed, which corresponds to an enantiomeric discrimination of approximately 94%. Molecular dynamic calculations were performed for some of the supramolecular complexes to in order to gain insight into the mode of molecular recognition between the macrocyclic compounds and ammonium salts; these results were consistent with experimental observations, which may be relevant to those in biochemical processes occurring in organisms. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Transition metals of arene derivatives with functionalized ionic liquid: DFT investigation, biological applications and electrochemical behavior of complexes(Elsevier Science Sa, 2022) Rafikova, Khadichakhan; Meric, Nermin; Guzel, Remziye; Arslan, Nevin; Binbay, Nil Ertekin; Kayan, Cezmi; Okumus, VeysiMononuclear transition metal complexes based on ionic liquid have been prepared and characterized in detail. The biological properties of the three complexes were evaluated using radical scavenging activity, reducing power, antibacterial effect, DNA binding and cleavage activity. Among the complexes, [3-[(2R)-2-({[dichloro(eta(6)-benzene)ruthenium]diphenylphosphanyl}oxy)-2-phenylethyl]-1-methyl-1H-imidazol-3-ium chloride] (4), demonstrated the highest radical scavenging (64.7 %) and reducing power activity (0.467) at 200 mu g/ml concentration. The highest zone of inhibition was obtained from [3-[(2R)-2-({[dichloro(eta(6)-p-cymene)ruthenium]diphenyl phosphanyl}oxy)-2-phenylethyl]-1-methyl-1H-imidazol-3-ium chloride] (3), against Bacillus cereus as 14 mm. Furthermore, all complexes were determined to have DNA binding and cleavage activities. Furthermore, theoretical DFT computations have also been carried out for the cationic complexes, to obtain minimum energy configuration of molecules. The effects of the chemical structures of three cationic complexes were also examined in relation to the variable property of electron-donating ligands for ruthenium-based complexes and iridium complex and their potential energy levels in ground and excited states HOMO and LUMO were determined.Öğe β-Hydroxyamide-based ligands and their use in the enantioselective borane reduction of prochiral ketones(Wiley, 2014) Azizoğlu, Murat; Erdoğan, Aslı; Arslan, Nevin; Turgut, Yılmaz; 0000-0003-0142-9215Hydroxyamide-based ligands have occupied a considerable place in asymmetric synthesis. Here we report the synthesis of seven -hydroxyamide-based ligands from the reaction of 2-hydroxynicotinic acid with chiral amino alcohols and test their effect on the enantioselective reduction of aromatic prochiral ketones with borane in tetrahydofuran (THF). They produce the corresponding secondary alcohols with up to 76% enantiomeric excess (ee) and good to excellent yields (86-99%). Chirality 26:21-26, 2013. (c) 2013 Wiley Periodicals, Inc.
