Yazar "Uyanik, Arzu" seçeneğine göre listele
Listeleniyor 1 - 10 / 10
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Antibacterial activity of new [(2-hydroxypropyl)-n-oximino]pyridines(ASIAN JOURNAL OF CHEMISTRY, 2008) Sen, Nejdet; Kar, Yakup; Kurbanov, Sultan; Uyanik, ArzuThe synthesized [(2-hydroxypropyl)-n-oximino]pyridine derivatives has been tested against the pathogenic four Gram-positive bacteria Bacillus cereus (ATCC 11778), Staphylococcus aureus (ATCC 6538), Sarcina lutea (ATCC 934 1) and Streptococs mutans (UCTC 10499) and three Gram-negative bacteria Salmonella typhimurium (1,4,5,12:;: 1,2), Pseudomonas aeruginosa (ATCC 27853) and Escherichia coli (ATCC 29998). Generally, all synthesized compounds (IVa-c) showed strong activity compared to antibiotic drug (cefalexin). However, among this compounds (IVa) showed excellent activity against Bacillus cereus (ATCC 11778), Sarcina lutea (ATCC 9341), Salmonella typhimurium (1,4,5,12:;: 1,2) and Escherichia coli (ATCC 29998) compared to cefalexin.Öğe Calixarene-proline functionalized iron oxide magnetite nanoparticles (Calix-Pro-MN): An efficient recyclable organocatalyst for asymmetric aldol reaction in water(ELSEVIER SCIENCE BV, 2015) Akceylan, Ezgi; Uyanik, Arzu; Eymur, Serkan; Sahin, Ozlem; Yilmaz, MustafaCalix[4]arene-based chiral organocatalyst derived from L-proline supported onto well-defined (15 +/- 3 nm) magnetic Fe3O4 nanoparticles was used as a highly active, recoverable, and reusable catalyst for the asymmetric aldol reaction in water without need for organic solvents. The chiral organocatalyst showed high catalytic activity (up to 94%), enantioselectivity (up to 93%) and diastereoselectivity (up to 97:3) for the reaction between cyclohexanone and aromatic aldehydes. The catalyst could easily separated using an external magnetic field and reused for several times without any significant loss of activity. (C) 2015 Elsevier B.V. All rights reserved.Öğe Chiral Calix[4]arenes-Bearing Prolinamide Functionality as Organocatalyst for Asymmetric Direct Aldol Reactions in Water(TAYLOR & FRANCIS LTD, 2018) Sahin, Ozlem; Eymur, Serkan; Uyanik, Arzu; Akceylan, Ezgi; Yilmaz, MustafaThe chiral calix[4]arene derivative (6) bearing an L-prolinamido group has been designed and proved to be a water compatible efficient organocatalysts for a direct enantioselective aldol reaction. Compound 6 catalyzes the aldol reaction of cyclohexanone and a variety of aromatic aldehydes yielding anti-aldol products in high yield with enantioselectivities of up to 93% and diastereoselectivity of up to 95:5.Öğe Direct enantioselective aldol reactions catalyzed by calix[4]arene-based L-proline derivatives in the water(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Eymur, Serkan; Akceylan, Ezgi; Sahin, Ozlem; Uyanik, Arzu; Yilmaz, MustafaTwo novel p-tert-butylcalix[4]arene-based chiral organocatalysts derived from L-proline have been developed to catalyze direct aldol reactions between cyclohexanone and aromatic aldehydes in water. Under the optimal conditions, high yields (up to 95%), enantioselectivities (up to 90%), and moderate diastereoselectivities (up to 65:35) were obtained. Considering the catalytic inefficiency of sole proline for the aldol reaction in water, these results clearly display the enormous effect of the hydrophobic part of calix[4]arene of compound A. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Effect of the glutaraldehyde derivatives of Calix[n]arene as cross-linker reagents on lipase immobilization(SPRINGER, 2009) Erdemir, Serkan; Sahin, Ozlem; Uyanik, Arzu; Yilmaz, MustafaSynthesis of the glutaraldehyde derivatives calix[n]arene (n = 4,6,8) (Calix[n]-GA) and using as cross-linkers for immobilization of Candida rugosa lipase (CRL) have been discussed in this paper. The amino functional calix[n]arene derivatives (Calix[n]-NH (2)) were synthesized via reduction of dinitrile, hexanitrile and octanitrile derivatives of calix[n]arenes. These amino functional calix[n]arene derivatives (Calix[n]-NH (2)) were converted to their aldehyde derivativatives with glutaraldehyde. The calix[n]arene derivatives were used in lipase immobilization in order to see the role of calix[n]arene binding site on the lipase activitiy and stability. The activity recovery of calix[n]arene-supported lipases (Calix[n]-CRL) based on the Calix[4]-CRL, Calix[6]-CRL and Calix[8]-CRL reaches to 53.5, 66.1 and 76.4%, respectively.Öğe Enantioselective hydrolysis of (R/S)-Naproxen methyl ester with sol-gel encapculated lipase in presence of calix[n]arene derivatives(ELSEVIER SCIENCE BV, 2009) Sahin, Ozlem; Erdemir, Serkan; Uyanik, Arzu; Yilmaz, MustafaLipases are enzymes that catalyses a variety of reactions, such esterifications, interesterification and hydrolysis. Several methods have been reported for the immobilization of lipases, such as deposition onto solid supports, covalent binding and encapsulation within a polymer matrix or silica glasses obtained by sol-gel techniques. In this study, the Candido rugosa lipase was encapsulated within a chemically inert sol-gel support prepared by polycondensation by tetraetoxysilane (TEOS)and octyltrietoxysilane(OTES) in the presence and absence of calix[n]arene, calix[n]-NH2 and calix[n]-COOH (n = 4,6,8) compounds as additives. The catalytic activity of the encapsulated lipases was evaluated into model reactions, i.e. the hydrolysis of p-nitrophenylpalmitate (p-NPP), and the enantioselective hydrolysis of rasemic Naproxen methyl ester that was studied in aqueous buffer solution/isooctane reaction system. The results indicated that the particularly calix[4,6]-NH2 and calix[6]-COOH based encapsulated lipases had higher conversion and enantioselectivity compared to the sol-gel free lipase. (C) 2009 Elsevier B.V. All rights reserved.Öğe Enhancing Effect of Calix[4]arene Amide Derivatives on Lipase Performance in Enantioselective Hydrolysis of Racemic Arylpropionic Acid Methyl Esters(TAYLOR & FRANCIS LTD, 2016) Uyanik, Arzu; Sen, Nejdet; Yilmaz, MustafaCalix[4]arene amide derivatives were employed as new additives within the sol-gel encapsulation of lipase from Candida rugosa (CRL) to improve its catalytic properties. Evaluation of catalytic activity of the encapsulated lipases was acheived by enantioselective hydrolysis of both racemates, Naproxen methyl ester and 2-phenoxypropionic acid methyl ester, in aqueous buffer solution/isooctane reaction system. Results show that enantioselectivity was improved by using calix[4]arene amide derivatives-based encapsulated lipases. The reaction of naproxen methyl ester resulted in 47.6% conversion (x) in 24h with 88.9% enantiomeric excess of substrate (ee(s)), analogous to an enantioselectivity (E) value of 297 (E = 137 for the encapsulated free enzyme). The conversion of 2-phenoxypropionic acid methyl ester, obtained was 48.4% with E value of 327, enantiomeric excess of substrate (ee(s)) of 92% for the reaction time of 1h (E = 211 for the encapsulated free enzyme).Öğe Improvement of catalytic activity of lipase from Candida rugosa via sol-gel encapsulation in the presence of calix(aza)crown(ELSEVIER SCI LTD, 2011) Uyanik, Arzu; Sen, Nejdet; Yilmaz, MustafaLipase from Candida rugosa (CRL) was encapsulated within a chemically inert sol-gel support in the presence of calix(aza)crowns as the new additives. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yields of the calix(aza)crown based encapsulated lipases were higher than that of the free lipase. Improved enantioselectivity was observed with the calix(aza)crown-based encapsulated lipases as compared to encapsulated free lipase. The reaction of Naproxen methyl ester resulted in 48.4% conversion for 24 h and 98% enantiomeric excess for the S-acid, corresponding to an E value of > 300 (E = 166 for the encapsulated free enzyme). Moreover, the encapsulated lipases were still retained about 18% of their conversion ratios after the sixth reuse in the enantioselective reaction. (C) 2010 Elsevier Ltd. All rights reserved.Öğe A New Piperidine Derivatized-Schiff Base Based "Turn-on" Cu(2+)Chemo-Sensor(SPRINGER/PLENUM PUBLISHERS, 2017) Uyanik, Ibrahim; Oguz, Mehmet; Bhatti, Asif Ali; Uyanik, Arzu; Yilmaz, MustafaIn this study, we report the synthesis of new Schiff base E-1-(((1-benzylpiperidin-4-yl)imino)methyl)naphthalenee-2-ol (L) and evaluation of its fluorescence response toward Cu2+ ion. Preliminary, solvent effect, metal selectivity and metal ligand ratio were analyzed through UV-Visible study. Fluorescence response toward Cu2+ was carried to assess the fluorescent property of synthesized Schiff base. The probe exhibited a higher fluorescence enhancement in the presence of Cu2+ over other metal ions (Ni2+, Zn2+, Hg2+, Co2+, Cd2+, Al3+, Fe2+, and Pb2+). The binding stoichiometry between L and Cu2+ has been investigated using Job's plot and Benesi-Hildebrand equation and it was found that ligand L can form 1:1 L-Cu2+ complex with binding constant (K (a)) of 4 x 10(4) LM-1.Öğe Upper rim-functionalized calix[4]arene-based L-proline as organocatalyst for direct asymmetric aldol reactions in water and organic media(PERGAMON-ELSEVIER SCIENCE LTD, 2014) Uyanik, Arzu; Bayrakci, Meylut; Eymur, Serkan; Yilmaz, MustafaThe synthesis of upper rim-functionalized calix[4]arene-based L-proline was described, and its catalytic efficiency as organocatalyst for the enantioselective aldol reaction in water was investigated. The results showed that the nature of the hydrophobic cavity of calixarene is critical for catalytic activity in water. The products of the reaction between various ketones and aldehydes with anti-configuration were obtained in high yields (up to 94%) with high diastereo- (up to 95:5 dr) and enantioselectivities (up to 80% ee). (C) 2014 Elsevier Ltd. All rights reserved.
