Synthesis, characterization, and biological evaluation of new copper complexes of naphthyl pyrazole ligands.

Two naphthalene pyrazole ligands were synthesized using KOH/DMSO and Cu catalyst and characterized with FT-IR, ESI-MS, 1H, and 13C NMR spectroscopies. The crystal structures of 1-(2-methylnaphthalen-1-yl)-1H-pyrazole (MeNap-Pz) ligand have been determined with X-ray crystal structure analysis. Reaction of the ligands with Cu(NO3)2x3.5H2O gave two new complexes and characterized with magnetic susceptibility, molar conductance, FT-IR, LCMS-MS, ICP-OES, NMR, thermogravimetric analysis, and ESR spectra. The spectral data of the ligands are coordinated to the metal ion through the nitrogen atoms of the pyrazole ring. Consequently, it has been determined that [Cu(MeNap-Pz)2(NO3)]NO3.2H2O complex showed square planar geometry and [Cu(NapMe-Pz)2(NO3)2].H2O complex showed octahedral geometry. All compounds were screened for in vitro antibacterial activity and copper complexes have been shown to be effective on bacteria.

Production of palladium nanocatalyst supported on modified gum arabic and investigation of its potential against treatment of environmental contaminants.

Removal of organic pollutants such as aromatic nitro compounds and dyes from wastewaters is very significant for environment, and the best strategy is their reduction/degradation in the presence of a metal catalyst. In this study, a new palladium nanocatalyst (GA-Sch-Pd) was prepared derived from modified gum arabic and characterized by FT-IR, TGA, FE-SEM, EDS, TEM, and XRD analyses. Then, the catalytic potential of GA-Sch-Pd nanocatalyst was tested in the catalytic reductions of different organic pollutants such as o-nitroaniline (o-NA), p-nitrophenol (p-NP), p-nitro-o-phenylenediamine (p-NPDA), p-nitroaniline (p-NA), congo red (CR), methylene blue (MB), and methyl orange (MO) by using NaBH4 in water. These tests showed GA-Sch-Pd nanocatalyst had high activity against reduction of nitroarenes and organic dyes at very short reaction durations. Moreover, GA-Sch-Pd nanocatalyst was easily separated and reused for several times. This study shows that GA-Sch-Pd nanocatalyst has a high potential for remediation of environmental pollutants in wastewaters.

Highly active and recyclable heterogeneous palladium catalyst derived from guar gum for fabrication of biaryl compounds.

In this study, a novel highly efficient heterogeneous palladium catalyst (GG-Pd) was prepared using guar gum, which is an environmentally friendly, easily available, fairly cheap, and renewable natural bio-polymer. Detailed characterization of GG-Pd catalyst was successfully performed by FT-IR, TG/DTG, SEM, EDS, XRD, and ninhydrin test, and it was evaluated as a heterogeneous catalyst against Suzuki-Miyaura coupling reactions of a series of aryl halides with phenylboronic acid. Catalytic performance studies showed that GG-Pd efficiently catalyzed Suzuki cross coupling reactions under solvent-free media and for a very short reaction time (5 min). Moreover, reusability tests showed that GG-Pd catalyst could be reused at least ten times with a minor decrease of its catalytic performance. Additionally, it was found that palladium leaching from the designed support was very minimal. This study shows that GG-Pd catalyst is a very useful and highly stable heterogeneous catalyst for Suzuki-Miyaura coupling reactions in terms of high catalytic performance and recyclability.

O-carboxymethyl chitosan Schiff base complexes as affinity ligands for immobilized metal-ion affinity chromatography of lysozyme.

We synthesized Ni2+-attached O-Carboxymethyl chitosan Schiff base complexes embedded composite cryogels (Ni2+-O-CMCS-CCs) by means of polymerization of gel-forming precursors at subzero temperatures. Prepared affinity cryogel showed excellent adsorption performance for lysozyme selected as model protein to test adsorption parameters, demonstrating an adsorption capacity of 244.6 mg/g (15.3 mg/g for Ni2+ minus O-CMCS-CCs), with fast adsorption equilibrium within 30 min and good reversibility. The performance of Ni2+-O-CMCS-CCs for lysozyme was also evaluated by SDS-PAGE, and a purification efficiency of 86.9% with 89.5% purification yield was determined. The swelling test, FT-IR, and SEM analysis were carried out for the characterization of Ni2+-O-CMCS-CCs. At the end of 35 adsorption-desorption cycles, there was no significant change in the adsorption capacity.

An easily recoverable and highly reproducible agar-supported palladium catalyst for Suzuki-Miyaura coupling reactions and reduction of o-nitroaniline.

Polysaccharides 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.

Production of novel palladium nanocatalyst stabilized with sustainable chitosan/cellulose composite and its catalytic performance in Suzuki-Miyaura coupling reactions.

In this study, we designed a new palladium nanocatalyst on chitosan/cellulose composite for the first time to increase the use of sustainable polysaccharides, which are cheap, non-toxic, environmental friendly, abundant in nature, and can be used as support materials for metallic nanoparticles. Physicochemical characterization of fabricated palladium nanocatalyst was illuminated with FT-IR, TG/DTG, SEM/EDAX, XRD, and ICP-OES analyses. Pd nanoparticles were found to be almost spherically structured, and the average particle size was 26-30nm. Then catalytic performance of the designed nanocatalyst was investigated in the synthesis of a series of biphenyl compounds via the Suzuki-Miyaura reaction by using the green method which is conducted in a very short-time, under low temperature, and without the presence of any toxic chemical solvents (e.g., 5min treatment in microwave oven at 400W at 50°C). As a result of the tests, palladium nanocatalyst showed excellent catalytic performance with high conversion yields for a wide range of substrates and with a very low catalyst loading for the Suzuki reactions. Sustainability performance of palladium nanocatalyst was also studied, and it is found that the catalyst was able to be recycled for eight successive runs.

Design and application of sporopollenin microcapsule supported palladium catalyst: Remarkably high turnover frequency and reusability in catalysis of biaryls.

Bio-based catalyst support materials with high thermal and structural stability are desired for catalysts systems requiring harsh conditions. In this study, a thermally stable palladium catalyst (up to 440°C) was designed from sporopollenin, which occurs naturally in the outer exine layer of pollens and is widely acknowledged as chemically very stable and inert biological material. Catalyst design procedure included (1) extraction of sporopollenin microcapsules from Betula pendula pollens (∼25µm), (2) amino-functionalisation of the microcapsules, (3) Schiff base modification and (4) preparation of Pd(II) catalyst. The catalytic activity of the sporopollenin microcapsule supported palladium catalyst was tested in catalysis of biaryls by following a fast, simple and green microwave-assisted method. We recorded outstanding turnover number (TON: 40,000) and frequency (TOF: 400,000) for the catalyst in Suzuki coupling reactions. The catalyst proved to be reusable at least in eight cycles. The catalyst can be suggested for different catalyst systems due to its thermal and structural durability, reusability, inertness to air and its eco-friendly nature.

Green heterogeneous Pd(II) catalyst produced from chitosan-cellulose micro beads for green synthesis of biaryls.

In green catalyst systems, both the catalyst and the technique should be environmentally safe. In this study we designed a green palladium(II) catalyst for microwave-assisted Suzuki CC coupling reactions. The catalyst support was produced from biopolymers; chitosan and cellulose. The catalytic activity of the catalyst was tested on 16 substrates in solvent-free media and compared with those of commercial palladium salts. Reusability tests were done. The catalyst was also used in conventional reflux-heating system to demonstrate the efficiency of microwave heating method. We recorded high activity, selectivity and excellent TONs (6600) and TOFs (82500) just using a small catalyst loading (1.5×10(-3)mol%) in short reaction time (5min). The catalyst exhibited a long lifetime (9 runs). The findings indicated that both green chitosan/cellulose-Pd(II) catalyst and the microwave heating are suitable for synthesis of biaryl compounds by using Suzuki CC coupling reactions.

Synthesis, characterization, and catalytic activity in Suzuki coupling and catalase-like reactions of new chitosan supported Pd catalyst.

The aim of this study is to analyze the synthesis of a new chitosan supported Pd catalyst and examination of its catalytic activity in: Pd catalyst was synthesized using chitosan as a biomaterial and characterized with FTIR, TG/DTG, XRD, (1)H NMR, (13)C NMR, SEM-EDAX, ICP-OES, Uv-vis spectroscopies, and magnetic moment, along with molar conductivity analysis. Biomaterial supported Pd catalyst indicated high activity and long life time as well as excellent turnover number (TON) and turnover frequency (TOF) values in Suzuki reaction. Biomaterial supported Pd catalyst catalyzed H2O2 decomposition reaction with considerable high activity using comparatively small loading catalyst (10mg). Redox potential of biomaterial supported Pd catalyst was still high without negligible loss (13% decrease) after 10 cycles in reusability tests. As a consequence, eco-friendly biomaterial supported Pd catalyst has superior properties such as high thermal stability, long life time, easy removal from reaction mixture and durability to air, moisture and high temperature.

Highly efficient, quick and green synthesis of biarlys with chitosan supported catalyst using microwave irradiation in the absence of solvent.

The aim of this study was to develop a quick reaction that had high activity with a small amount of catalyst, which could be an eco-friendly alternative technique for the synthesis of biarlys in Suzuki coupling reactions. First, a novel chitosan Schiff base supported Pd(II) catalyst was synthesized, and its structure was illuminated with FTIR, (1)H NMR, (13)C NMR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV-vis, magnetic moment, and molar conductivity techniques. Subsequently, the catalytic activity of the catalyst was tested in Suzuki C-C reactions under microwave irradiation using a solvent-free reaction condition. The catalytic tests showed an excellent activity with a small load of the catalyst (0.02 mol%) in 4 min. The catalyst showed seven runs without loss of activity, and high values of turnover numbers (TON) and turnover frequency (TOF) were obtained. The novel biopolymer supported Pd(II) catalyst provided much faster reaction times, higher yields, and reusability under microwave heating compared to classic heating methods.

Cu(II) and Pd(II) complexes of water soluble O-carboxymethyl chitosan Schiff bases: Synthesis, characterization.

This study reports the synthesis of two new water soluble O-carboxymethyl chitosan Schiff bases (OCMCS-5 and OCMCS-6a) and their Cu(II) and Pd(II) complexes. Characterizations of these complexes were carried out with FTIR, elemental analysis, (13)C CPMAS, UV-vis, magnetic moment and molar conductivity techniques. The degrees of substitution (DS) for OCMCS-5a and OCMCS-6a were determined to be 0.48 and 0.44 in elemental analysis. The solubility test revealed that OCMCS-5a and OCMCS-6a dissolved thoroughly in water. The surface morphologies of chitosan (CS), OCMCS-5a, OCMCS-6a and their complexes were studied with SEM-EDAX. Thermal stability of the synthesized compounds was evaluated by TG/DTG and their crystallinity values were investigated with powder X-ray diffraction. Cu(II) and Pd(II) contents of the complexes were estimated with ICP-OES. The characterization studies demonstrated that the thermal stability and crystallinity values of the OCMCS-5a and OCMCS-6a were lower than those of CS.

Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes.

In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and (13)C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a] · 2H2O and [O-CMCS-4a] · 2H2O). Thus, the solubility problem of chitosan in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2] · 2H2O and [O-CMCS-4a-Cu(OAc)2] · 2H2O, was conducted using FTIR, UV-Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements.

Physicochemical comparison of chitin and chitosan obtained from larvae and adult Colorado potato beetle (Leptinotarsa decemlineata).

Chitins and chitosans obtained from larva and adult Colorado potato beetles (Leptinotarsa decemlineata) were physico-chemically characterized and differences between adults and larvae were identified. The dry weight chitin contents of the adult Colorado potato beetles and larvae were determined as 20% and 7%, respectively. The chitin produced chitosan yields of 72% from the adult Colorado potato beetles and 67% from the larvae. FTIR analysis showed that the isolated chitins were in the alpha form. Crystalline index values, determined by XRD, were 72% for larvae and 76% for adults. The degradation temperatures of the isolated chitin structures were measured by TGA, and this showed that the chitin from adult Colorado potato beetles had a more stable structure than that from the larvae. The surface morphologies of the isolated chitin and chitosan structures were analysed with SEM and it was revealed that these structures consisted of nanofibres. According to elemental analysis, the purity of chitin and chitosan from adults was greater than that from the larvae. The results of molecular analysis showed that the chitosans from adults (2.722 kDa) and larvae (2.676 kDa) of the Colorado potato beetle have low molecular weights. Antimicrobial and antioxidant activities of both adult and larval chitosans were determined. The adult potato beetle is more appropriate than the larvae as an alternative chitin source because of the fact that its dry weight chitin content, chitosan yield and purity of chitin are higher than those from the larvae, and its antimicrobial and antioxidant activities are also higher than those from the larvae.

Tris(2,2'-bipyridine-κ(2) N,N')cobalt(II) bis-(hexa-fluoridophosphate).

In the title compound, [Co(C10H8N2)3](PF6)2, the Co(II) atom is coordinated by the six N atoms of three 2,2'-bipyridyl ligands and adopts a highly distorted octa-hedral geometry. The crystal used was a merohedral twin, the refined ratio of twin components being 0.820 (1):0.180 (1). The crystal structure features weak C-H⋯F inter-actions, forming a three-dimensional network.