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Öğe A combination method based on chitosan adsorption and duckweed (Lemna gibba L.) phytoremediation for boron (B) removal from drinking water(Taylor & Francis, 2018) Türker, Onur Can; Baran, TalatThe metalloid boron (B) and its compounds widely exist in the environment, and boron can have hazardous effects on plants, animals, and human beings when it is found in high concentrations in water bodies. It is difficult and costly to remove B with conventional treatment methods from drinking water. Therefore, alternative and cost-effective treatment techniques are necessary. In this study, for the first time, a novel and environmentally friendly method based on the phytoremediation ability of chitosan and duckweed (Lemna gibba L.) combination was evaluated for B removal from drinking water. Our results from batch adsorption experiment indicated that the highest B uptake capacity of chitosan bead was found as 3.18mg/g, and we determined the optimal B sorption occurs at pH value of 7. The Langmuir isotherm and pseudo-second-order kinetic model better fitted the equilibrium obtained for B removal. B in drinking water could be reduced to less than 2.4mg L-1 when 0.05g of plant-based chitosan beads and 12 L. gibba fronds were used in the 4-day treatment period.Öğe A new activated carbon-supported Pd–ZnO catalyst for Heck Cross-coupling reactions(Elsevier B.V., 2023) Karaoğlu, Kaan; Özçifçi, Zehra; Çalışkan, Melike; Türker Akçay, Hakkı; Baran, TalatIn this work, to develop catalysts for Heck-type coupling reactions, a hybrid ZnO-Pd nanocatalyst was fabricated on activated carbon sourced from polymer debris. Such techniques as transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) surface area analysis were applied for the identification of hybrid materials. The catalytic conversion capacity of the hybrid material was tested by Heck cross-coupling reactions through a series of aryl iodides and bromines with styrene. It was observed that cross-coupling reactions were catalyzed by designed hybrid material with a reaction yield of more than 90%. The recyclability of the hybrid was also tested by Heck reaction of 1-bromo-4-nitrobenzene with styrene, and the hybrid catalyst showed remarkable stability up to 5 cycles.Öğe A new air and moisture stable robust bio-polymer based palladium catalyst for highly efficient synthesis of biaryl compounds(Wiley, 2018) Baran, Talat; Yılmaz Baran, Nuray; Menteş, AyferThe designs of robust natural polymer based catalysts are important for catalytic systems in the view of industrial purposes and green chemistry. In this study, a new air and moisture stable robust starch-based Pd(II) catalyst was designed and characterized with different analytical techniques. Catalytic behavior of the prepared robust palladium(II) catalyst was investigated in the Suzuki coupling reactions of aryl iodides, aryl bromides and aryl chlorides with phenyl boronic acid under microwave irradiation using very short reaction time. Sustainability and reusability of the catalyst was also explored under benign conditions. As a result of the catalytic tests, the green catalyst gave excellent biphenyl yields, TONs and TOFs with very low catalyst loading. More importantly, the robust catalyst has showed that it can be reused several times without important loses from its activity in the coupling reactions. The study showed that the robust starch-based Pd(II) catalyst had more advantages than other catalysts reported in the literature due to its economic, sustainable, thermal durable, environmentally friendly and practice properties.Öğe A new chitosan Schiff base supported Pd(II) complex for microwave-assisted synthesis of biaryls compounds(Elsevier Ltd., 2017) Baran, TalatIn this study, a new heterogeneous palladium (II) catalyst that contains O-carboxymethyl chitosan Schiff base has been designed for Suzuki coupling reactions. The chemical structures of the synthesized catalyst were characterized with the FTIR, TG/DTG, ICP-OES, SEM/EDAX, H-1 NMR, C-13 NMR, GC/MS, XRD, and magnetic moment techniques. The reusability and catalytic behavior of heterogeneous catalyst was tested towards Suzuki reactions. As a result of the tests, excellent selectivity was obtained, and by-products of homo coupling were not seen in the spectra. The biaryls products were identified on a GC/MS. In addition, it was determined in the reusability tests that the catalysts could be used several times (seven runs). More importantly, with very low catalyst loading (6 x 10(-3) mol %) in very short reaction time (5 min), chitosan Schiff base supported Pd(II) complex gave high TON and TOF values. These findings showed that Schiff base supported Pd(II) catalyst is suitable for Suzuki cross coupling reactions. (C) 2017 Elsevier B.V. All rights reserved.Öğe A new method for fast chitin extraction from shells of crab, crayfish and shrimp(Taylor & Francis Ltd., 2015) Kaya, Murat; Baran, Talat; Karaarslan, MuhsinA new method for quick chitin isolation from the shells of crab, crayfish and shrimp is described. The main difference between the new method and the conventional method is two sodium hypochlorite (NaClO) treatments for 10min each before the processes of demineralisation and deproteinisation. After the NaClO treatment, only 15min is adequate for the demineralisation and 20min for the deproteinisation processes. Newly extracted chitin from crab, crayfish and shrimp shells and commercial chitin were characterised using FT-IR, TGA, X-ray diffractometry and elemental analysis. From the results, it was observed that the chitins isolated with the new method and the commercial chitin had almost the same physicochemical properties. The advantage of the new method compared to traditional methods is the relatively rapid chitin extraction. When compared to the traditional chitin extraction method, the proposed method appears to be promising regarding its time and energy saving nature.Öğe A physicochemical characterization of fully acetylated chitin structure isolated from two spider species: With new surface morphology(Elsevier, 2014) Kaya, Murat; Seyyar, Osman; Baran, Talat; Erdoğan, Sevil; Kar, MusaSpiders are a huge group which includes more than 44,000 species. But there has been no study of the chitin structure of spiders. In this study we physicochemically characterized chitin structure of two common spider species (Geolycosa vultuosa and Hogna radiata). Chitin content was determined as 8-8.5% for G. vultuosa and 6.5-7% for H. radiata. FTIR, TGA and XRD results showed that the chitin structures are in a-form. Environmental scanning electron microscopy (ESEM) revealed that the surface morphology of each species is different. Chitin yielded from G. vultuosa has two different pore structures. The type one pore is rarely sequenced and its size ranges between 190 and 240 nm, while the type two pore is tightly sequenced and its size ranges between 11 and 32 nm. There is no information in previous studies about the chitin structure with two different pore morphologies. A new chitin surface morphology has been determined in G. vultuosa. The chitin isolated from H. radiata, has classic morphology: nanofibre structures (10-17 nm) and 195-260 nm sized pores. Acetylation degree of the chitin samples was calculated as 97% for G. vultuosa and 99% for H. radiata in accordance with elemental analysis results. (C) 2014 Elsevier B.V. All rights reserved.Öğe A promising nanocatalyst: Upgraded Kraft lignin by titania and palladium nanoparticles for organic dyes reduction(Elsevier B.V., 2021) Nezafat, Zehra; Mohazzab, Bahareh Feizi; Jaleh, Babak; Nasrollahzadeh, Mahmoud; Baran, Talat; Shokouhimehr, MohammadrezaThe evaluation of dye degradation was adorned a great interest due to scarcity of water, courtesy of industrialization. Here, Kraft lignin was upgraded by immobilization of TiO2 nanoparticles (NPs) by the reflux method (KL-T). Palladium (Pd) NPs were produced in a promising way by laser ablation in liquid (LAL) and loaded on KL-T to prepare an efficient nanocatalyst (KL-T/Pd). The synthesized KL-T/Pd is characterized by X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectrometry (EDX), and Transmission electron microscope (TEM) analyses. The KL-T/Pd nanocomposite was applied as an efficient and novel nanocatalyst for the reduction of methylene blue (MB) and methyl orange (MO) by NaBH4 as a reducing agent in aqueous media at ambient temperature. Our experimental results displayed that the 1 mg of KL-T/Pd catalyst can be reduced MB and MO organic dyes within 23 and 8 s, respectively at room temperature. The KL-T/Pd nanocatalyst can be recycled and reused four times with no considerable loss of performance. Having different advantages such as high catalytic performance, safe synthesis method, and high stability, lignin was suggested as a natural substrate.Öğe An easily fabricated palladium nanocatalyst on magnetic biochar for Suzuki-Miyaura and aryl halide cyanation reactions(Royal Society of Chemistry, 2021) Turunç, Ersan; Akay, Sema; Baran, Talat; Kalderis, Dimitrios; Tsubota, Toshiki; Kayan, BerkantBiochar is a carbon-rich solid, the surface of which is covered with a high density of functional carbonyl, hydroxyl and carboxylic acid groups. In this work, palladium nanoparticles were embedded on magnetic biochar and a new reusable and environmentally-friendly catalyst was developed and applied for the promotion of Suzuki-Miyaura C-C coupling and cyanation reactions. The high-carbon (77%), low-ash content (5.8%) and the relatively high surface area (266 m(2) g(-1)) of pine tree biochar (PTB) suggested that it might be highly suitable as a catalyst substrate. The Fe3O4-Pd-biochar nanocomposite was successfully characterized using SEM, TEM, EDX, FT-IR, BET and XRD. Its catalytic role was initially evaluated using p-NO2C6H4I as a model reactant (for both types of reactions) and later for the production of biaryls and benzonitriles from a wide range of aryl halides under mild reaction conditions. Biaryls and benzonitriles were characterized using GC-MS. In the case of the Suzuki-Miyaura reaction, the optimum yield of 98% was obtained with a catalyst concentration of 0.04 mol%, microwave irradiation of 400 W, and a residence time of 5 min, using K2CO3 as the base. With respect to the cyanation reaction, dimethylformamide, Na2CO3 and 6 h were the optimum solvent, base and reaction duration, respectively. Subsequently, the nanocatalyst showed excellent catalytic activity in both reactions, achieving >88% yields in most cases, regardless of the aryl iodide or bromide used and the type of substitution.Öğe An easily recoverable and highly reproducible agar-supported palladium catalyst for Suzuki-Miyaura coupling reactions and reduction of o-nitroaniline(Elsevier Science Bv, 2018) Baran, Talat; Yılmaz Baran, Nuray; Menteş, AyferPolysaccharides are excellent support materials for catalytic systems due to their superior metal binding capacity, high mechanical strength, and green nature. Among the polysaccharides, agar can be considered a good support material for catalytic reactions from the point of its low cost, easy availability, high thermal durability, and biodegradability. In this study, agar-supported palladium catalyst (AG-Pd) was designed for the first time, and then its catalytic performance was tested towards (i) Suzuki-Miyaura coupling reactions and (ii) catalytic reduction of o-nitroaniline to o-phenylenediamine under mild reaction conditions. Additionally, the reproducibility of the designed AG-Pd catalyst was investigated in both catalytic reactions, and the tests showed that the catalyst could be reused many times. AG-Pd catalyst displayed excellent selectivity and efficiency in Suzuki-Miyaura coupling reactions in only 6 min under solvent-free media. In addition, AG-Pd catalyst provided good catalytic reduction by completely reducing o-nitroaniline in 90 s at room temperature. These findings reveal that agar is a good support material, and it can be used for different catalytic systems as a support. (C) 2018 Elsevier B.V. All rights reserved.Öğe An environmental catalyst derived from biological waste materials for green synthesis of biaryls via Suzuki coupling reactions(Elsevier Science Bv, 2016) Baran, Talat; Sargın, İdris; Kaya, Murat; Menteş, AyferSynthesis of bio-macromolecular supported catalysts has gained much recent attention due to their greener nature. Among the biopolymers, chitosan is widely used as a support material due to its high affinity for metal ions. In this study, chitosan-Ulva sp. (green alga) composite microbeads were prepared as a support material for palladium catalyst. Ulva sp. particles were incorporated into chitosan matrix to enhance the interaction with palladium ions. The catalytic performance of chitosan-Ulva supported Pd(II) catalyst was investigated in the synthesis of biaryls via the Suzuki coupling reaction. All the experiments were conducted without using any solvent under the microwave irradiation, which is also considered as a green technique. This green catalyst exhibited high selectivity and efficiency in the reactions of phenyl boronic acid with different aryl halides in only 4 min at low temperature (50 degrees C). Excellent TON and TOF values were achieved for the catalyst; 4950 and 75000. In addition, the catalyst did not lose its activity even after 8 cycles. It showed high thermal stability (216.8 degrees C) and durability in presence of oxygen. This green catalyst has a potential to be used in pharmacology, medicine and cosmetics. (c) 2016 Elsevier B.V. All rights reserved.Öğe An inclusive physicochemical comparison of natural and synthetic chitin films(Elsevier, 2018) Kaya, Murat; Salaberria, Asier M.; Mujtaba, Muhammad; Labidi, Jalel; Baran, Talat; Mulercikas, Povilas; Duman, FatihNatural and synthetic chitin films, obtained from the same source were produced and their physicochemical properties were examined comparatively. Firstly, natural chitin film was obtained from elytra of an insect (Oryctes nasicornis L) and purity of the obtained chitin film (degree of acetylation: 79 +/- 2%) was demonstrated by solid state C-13 nuclear magnetic resonance (C-13 NMR). Then, the synthetic film was produced by dissolving of natural chitin film in LiCl-DMAc. The obtained natural and synthetic films were characterized by AFM, TGA, DSC, FTIR, mechanical properties, light transmission and contact angle. The analyses result demonstrated that natural chitin film lost very important properties such as high thermal stability, transparency, nanofibrous nature, tensile strength, Young's modulus and hydrophobicity after transforming the synthetic film. (C) 2017 Elsevier B.V. All rights reserved.Öğe Antimicrobial and antioxidant properties of Ceriodaphnia quadrangula ephippia chitosan(Editura Ars Docendi, 2016) Aşan Özüsağlam Meltem; Çakmak, Yavuz Selim; Kaya, Murat; Erdoğan, Sevil; Baran, Talat; Menteş, Ayfer; Saman, İhsanThe chitosan from ephippia of Ceriodaphnia quadrangula (Crustaceae) has been fully characterized in our previous study, and in this work it was tested for antibacterial and antifungal activities against human and fish pathogens, while also determining its antioxidant activities. Using the disc diffusion method showed that the antimicrobial activity was observed against all tested microorganisms in the range of 12.84 - 16.28 mm.The minimal bactericidal concentration (MBC) value was found to be 0.63 - 2.50 mg/ml. Chitosan obtained from C. quadrangula ephippia showed higher antimicrobial activity against some pathogenic bacteria than commercial antibiotics. While chitosan inhibited 35.83% of the 1,1-diphenyl-2-picrylhydrazyl radicals (at 5 mg/ml), it showed an activity of 14.48 µg/ml for ferrous ion reducing. Consequently, it is suggested that chitosan obtained from the ephippia of C. quadrangula (Crustacea) can be used as food/feed additives, preservatives or in the pharmaceutical industry instead of using synthetic antimicrobials and antioxidants. © 2016 University of Bucharest.Öğe Antitumor activity of chitosan from mayfly with comparison to commercially available low, medium and high molecular weight chitosans(Springer, 2018) Tan, Gamze; Kaya, Murat; Tevlek, Atakan; Sargın, İdris; Baran, TalatInsects' cuticles have a potential to be evaluated as a chitin source. Especially adults of aquatic insects like mayflies (order Ephemeroptera) swarm in enormous numbers in artificially lit areas while mating in spring and then die by leaving huge amounts of dead insects' bodies. Here in this study, mayfly corpses were harvested and used for production of low MW chitosan. Dried mayfly bodies had 10.21% chitin content; mayfly chitin was converted into chitosan with efficiency rate of 78.43% (deacetylation degree, 84.3%; MW, 3.69 kDa). Cytotoxicity and anti-proliferative activity of mayfly and commercially available shrimp chitosans (low, medium, and high MW) were determined on L929 fibroblast and three different cancer types including HeLa, A549, and WiDr. Apoptosis and necrosis stimulating potential of mayfly and commercial chitosans were also evaluated on A549 and WiDr cells using acridine orange and propidium iodide dual staining to observe morphological changes in nuclei and thus to reveal the predominant cell death mechanism. The effects of chitosans have varied depending on cell types, concentration, and chitosan derivatives. Mayfly and low MW chitosans had a cytotoxic effect at a concentration of 500 mu g mL(-1) on non-cancer cells. At concentrations below this value (250 mu g mL(-1)), mayfly and commercial chitosans except high MW one exhibited strong inhibitory activity on cancer cells especially A549 and WiDr cells. Mayfly chitosan induced early and late apoptosis in A549 cells, but late apoptosis and necrosis in WiDr cells. This study suggests that dead bodies of mayflies can be used for production of low MW chitosan with anti-proliferative activity.Öğe Antitumor and apoptotic effects of new-generation platinum compounds on human leukemia cell lines HL-60 and K562(Springer, 2022) Karacaer, Neslihan Tekin; Kerimoğlu, Barış; Baran, Talat; Tarhan, Mehtap; Menteş, Ayfer; Öztürk, KamileThe goal of this investigation is to report the fabrication, characterization, cytotoxicity, and apoptotic assessment of new platinum based compounds on K562 and HL-60 human leukemia cells. Two new platinum (II) compounds, Pt-5a and Pt-6a, were prepared and characterized by fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy ((HNMR)-H-1), environmental scanning electron microscopy (ESEM) and energy dispersive spectrometer (EDS) techniques. The cytotoxic activities of the compounds were evaluated by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) test. Caspase-3, B-cell lymphoma 2 (Bcl-2), and B-cell lymphoma 2 associated X protein (Bax) gene expressions were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) to illuminate the mechanism of apoptosis. The results present that the applied compounds exhibited dose-dependent cytotoxic effects in-vitro. Pt-5a and Pt-6a compounds caused a rise in Bax in HL-60 cells while a reduction in Bcl-2 was recorded in all applied doses. In HL-60 cells, an increase in caspase-3 was detected at doses of 25 mu M and 50 mu M of Pt-5a and 30 mu M of Pt-6a. The treatment with 40 mu M of Pt-5a increased caspase-3 and Bax in K562 cells compared with control cells. Bcl-2 was found to be low in 20 mu M of Pt-5a treatment in K562 cells. Pt-6a caused a significant increase in caspase-3 at the dose of 30 mu M in the same cells. It is proposed that the newly synthesized platinum compounds may prove to be significant in the development of anticancer-effective drugs as they trigger apoptosis in a dose-dependent manner.Öğe Assessment of a Pd-Fe3O4-biochar nanocomposite as a heterogeneous catalyst for the solvent-free Suzuki-Miyaura reaction(Elsevier, 2021) Akay, Sema; Baran, Talat; Kayan, Berkant; Kalderis, DimitriosThe objective of this study was the development of a novel, biochar-based Pd nanocatalyst and its evaluation for the promotion of the Suzuki-Miyaura coupling reaction. The Fe3O4-Pd-biochar composite was successfully characterized through a range of spectroscopic and elemental analysis techniques. Its catalytic activity was initially assessed using p-NO2C6H4I as a model reactant and later for the production of biaryls from a wide range of aryl halides, under microwave irradiation and solvent-free conditions. The optimum yield of 99% was obtained at a catalyst dosage of 8 mg, microwave irradiation of 400 W, 6 min residence time, using K2CO3 as the base. Furthermore, the catalyst promoted the Suzuki-Miyaura reaction of aryl iodides and bromides (yields in the range of 88-97 and 86-97%, respectively), but was less successful for aryl chlorides (yields 78-83%). The presence of Fe3O4 allowed for the quick recovery of the catalyst, whereas repeated runs established its recyclability.Öğe Bat guano as new and attractive chitin and chitosan source(BioMed Central Ltd., 2014) Kaya, Murat; Seyyar, Osman; Baran, Talat; Türkeş, TuncayIntroduction: Chitin is a biopolymer that forms the exoskeleton of arthropods, and is found in the cell walls of fungi. It has a wide range of uses in fields such as cosmetics, pharmacy, medicine, bioengineering, agriculture, textiles and environmental engineering based upon its nontoxic, ecofriendly, biocompability and biodegradability characteristics. Commercially, chitin is obtained from processing the outer skeleton of Crustacea such as shrimp, crab, prawn and crayfish after they have been consumed as food. The study aims to examine the nature of bat guano and to determine if it is a practical source of chitin, which has not been done previously. Results: In this study, the chitin content of dry bat guano samples was found to be 28%. The bat guano, which was collected from Karacamal Cave, came from the bat species Rhinolophus hipposideros. The chitosan yield of this chitin was 79%. The chitin produced from the bat guano was determined to be in the alpha form according to Fourier transform infrared spectroscopy (FTIR) results. The crystallinity of the chitin and chitosan samples was calculated as 85.49 and 58.51% respectively by X-ray crystallography (XRD) experiments. According to scanning electron microscope (SEM) micrographs, the chitin and chitosan structures were shaped like nanofibers. The thermogravimetric analysis (TGA) results showed that both chitin and chitosan had two step weight losses, which are characteristic of these materials. The nitrogen content of the chitin and chitosan was 6.47 and 7.3% respectively according to the elemental analysis results. Conclusions: In this research, it has been observed that bat guano can be considered to be an alternative source of chitin and chitosan to crab, shrimp, crayfish and krill.Öğe Bentonite-supported furfural-based Schiff base palladium nanoparticles: an efficient catalyst in treatment of water/wastewater pollutants(Springer, 2020) Nasrollahzadeh, Mahmoud; Baran, Talat; Sajjadi, Mohaddeseh; Yılmaz Baran, Nuray; Shokouhimehr, MohammadrezaThis study reports a versatile process for the fabrication of palladium nanoparticles (Pd NPs) stabilized on Schiff base modified Unye bentonite with a coordination performance of furfural ligand (UN-Fur@PdNPs) as a promising nanocatalyst in the reduction of organic/inorganic pollutants. APTES ((3-aminopropyl)triethoxysilane)-modified UN-Fur@PdNPs has been synthesized via a facile, multi-step procedure without any additional stabilizing/reducing agents. The characterization of UN-Fur@PdNPs sample was carried out by FTIR, XRD, EDS, elemental mapping, STEM, TEM, HRTEM, and TG/DTG analyses which indicate the formation of Pd NPs (~ 10 nm) on the surface of UN-Fur. The catalytic activity/stability of the as-prepared nanocatalyst has also been assessed in the reduction of 4-nitrophenol (4-NP), Congo Red (CR), Methylene Blue (MB), and Methyl Orange (MO) dyes by NaBH4 (sodium borohydride) and chromium [Cr(VI)] by HCOOH (formic acid) in water. Catalytic efficiency retention has also been obtained after eight cycles. UN-Fur@PdNPs showed excellent catalytic performance and high stability/sustainability in the reduction of all five targeted organic/inorganic pollutants.Öğe Bio-synthesis and structural characterization of highly stable silver nanoparticles decorated on a sustainable bio-composite for catalytic reduction of nitroarenes(Elsevier Science Bv, 2019) Baran, TalatBio-polymers are the most significant natural alternative stabilizers compared to their synthetic counterparts for fabrication of noble metal nanoparticles because of their higher thermal stability, renewability, low cost, eco-friendliness, strong mechanical capacity, and biodegradability properties. Therefore, a new bio-composite (CMC-Pct-AG), which is consisted of sodium carboxymethyl cellulose, agar, and pectin natural biopolymers, was fabricated as an immobilizing agent in this study. Then, highly stable silver nanoparticles (Ag NPs@CMC-AG-Pct) were successfully decorated on the surface of designed CMCPct-AG without the use of any hazardous reducing agents, and their chemical structures were illuminated with Uv-Vis, FT-IR, TG/DTG, SEM, EDS, XRD, and ICP-OES analyses. Subsequently, the catalytic performance of Ag NPs@CMC-AG-Pct was studied in the reduction of various nitroarenes in the presence of NaBH4 at room temperature. These tests indicate that Ag NPs@CMC-AG-Pct is an efficient catalyst which converts nitroarenes to desired amines with good yields and short reaction times. Reproducibility of the catalyst was also investigated, and it is found that Ag NPs@CMC-AG-Pct served several times as a retrievable and reusable catalyst for catalytic reduction of nitroarenes. (C) 2019 Elsevier B.V. All rights reserved.Öğe Biosynthesis of highly retrievable magnetic palladium nanoparticles stabilized on bio-composite for production of various biaryl compounds and catalytic reduction of 4-nitrophenol(SPRINGER, 2019) Baran, TalatIn this study, eco-friendly palladium nanoparticles (Pd NPs@Pct-CMC/Fe3O4) with magnetic recoverability, high efficiency, renewability, reusability, and high thermal stability were fabricated on pectin/carboxymethyl cellulose composite and their chemical structures were illuminated by FT-IR, XRD, SEM, EDS mapping, ICP-OES, and TG/DTG analyses. It was found that average size of the palladium nanoparticles changed in the range of 49-85nm, and they homogeneously dispersed on the composite. Then, catalytic performance of Pd NPs@Pct-CMC/Fe3O4 was investigated against (i) synthesis of various biaryl compounds under solvent-free media and (ii) catalytic reduction of highly toxic 4-nitrophenol using NaBH4 in aqueous medium at room temperature. The catalytic tests showed that Pd NPs@Pct-CMC/Fe3O4 is excellent catalyst for synthesis of biaryl compounds by giving high reaction yields in 7min. Pd NPs@Pct-CMC/Fe3O4 also indicated superior catalytic performance for catalytic reduction of 4-nitrophenol in only 100s. More importantly, Pd NPs@Pct-CMC/Fe3O4 displayed excellent reproducibility in the synthesis of various biaryl compounds and catalyticreduction of 4-nitrophenol due to their magnetically separable nature. As a consequence, this study revealed that Pd NPs@Pct-CMC/Fe3O4 accelerated the fabrication of biaryls and the catalyticreduction of 4-nitrophenol. [GRAPHICS] .Öğe Carboxymethyl chitosan schiff base supported heterogeneous palladium(II) catalysts for suzuki cross-coupling reaction(Elsevier Science Bv, 2015) Baran, Talat; Açıksöz, Eda; Menteş, AyferIn this study, two new O-carboxymethyl chitosan Schiff bases supported Pd(II) catalyst were synthesized (OCMCS-3aPd and OCMCS-4aPd). The catalysts were characterized with FTIR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV vis, magnetic moment and molar conductivity. The catalytic activities of these catalysts were tested in the synthesis of biaryl compounds by Suzuki cross-coupling reactions. Characterizations of the biaryls were performed with GC MS and H-1 NMR. In synthesis of the biaryl compounds in the presence of the Pd(II) catalyst, high selectivity was observed; no homo-coupling byproducts were detected in the spectra. A reusability test demonstrated that the catalysts were highly efficient even after ten run. The mercury poisoning and leaching tests indicated that the catalysts have heterogeneous nature.
