Synthesis,antimicrobial and thermal studies of nitropyridine-substituted double armed benzo-15-crown-5 ligands; alkali (Na+ and K+) and transition metal (Ag+) complexes; reduction of nitro compounds

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Nitropyridine substituted double-armed benzo 15-crown-5 compounds (1–4) were synthesized by the reactions of...     

Pre-service mathematics teachers’ concept images of radian

This study investigates pre-service mathematics teachers’ concept images of radian and possible sources of such images. A multiple-case study was conducted for this study. Forty-two pre-service mathematics teachers completed a questionnaire, which aims to assess their understanding of radian. Six of them were selected for individual interviews on the basis of theoretical sampling. The data indicated that participants’ concept images of radian were dominated by their concept images of degree. As the data in this study suggested, pre-service mathematics teachers were reluctant to accept trigonometric functions with the inputs of real numbers but rather they use value in degrees. More interestingly, they have two distinct images of π : π as an angle in radian and π as an irrational number.     

Synthesis of New Chiral and Racemic 1,3‐Dioxolanes

A series of chiral 1,3‐dioxolanes, 3 – 12 , with >99% ee values, have been synthesized. This is the first study of chiral ketalization reaction starting from ketones with aryl, monosubstituted aryl, and long alkyl chains (C₁₁—AC₁₃). Their ee values were determined by chiral high‐performance liquid chromatography (HPLC) on Chiralcel OD column, using their racemic 1,3‐dioxolanes rac‐ 3 – 12 , which were also synthesized for the first time. These chiral and racemic 1,3‐dioxolanes were characterizated by infrared, NMR (¹H, ¹³C), mass spectrometry, elemental analysis, optical rotation, and chiral HPLC.     

Evaluation of oil content and fatty acid composition of five endemic Bupleurum species growing in the Central Anatolia region of Turkey

The fatty acid composition of five endemic Bupleurum (Apiaceae) species was analysed by GC technique for their nutritional value. The amount of oil content of the species varied from 3.77% to 7.03%. Twenty-one fatty acids were identified in the oils. The fatty acid composition of the studied species contained oleic, palmitic and linoleic acids as the major components. Oleic acid ranged from 8.81% to 68.30%, while the levels of palmitic acid were found to be between 12.47% and 47.85%. Bupleurum lycaonicum, Bupleurum sulphureum and Bupleurum heldreichii are very good sources of oleic acid. The remaining species were characterised as containing the highest level of palmitic acid. In this study, the total saturated fatty acids ranged between 15.02 and 65.20%, while total monounsaturated fatty acids were between 18.10 and 70.65%. The total polyunsaturated fatty acid accounted for 13.47-35.20% of the studied fatty acids. Therefore, we can conclude that Bupleurum oils have a significant nutritional value.     

Block‐brush copolymers via ROMP and sequential double click reaction strategy

We report an efficient way, sequential double click reactions, for the preparation of brush copolymers with AB block‐brush architectures containing polyoxanorbornene (poly (ONB)) backbone and poly(ε‐caprolactone) (PCL), poly(methyl methacrylate) (PMMA) or poly(tert‐butyl acrylate) (PtBA) side chains: poly(ONB‐g‐PMMA)‐b‐poly(ONB‐g‐PCL) and poly(ONB‐g‐PtBA)‐b‐poly(ONB‐g‐PCL). The living ROMP of ONB affords the synthesis of well‐defined poly(ONB‐anthracene)₂₀‐b‐poly (ONB‐azide)₅ block copolymer with anthryl and azide pendant groups. Subsequently, well‐defined linear alkyne end‐functionalized PCL (PCL‐alkyne), maleimide end‐functionalized PMMA (PMMA‐MI) and PtBA‐MI were introduced onto the block copolymer via sequential azide‐alkyne and Diels‐Alder click reactions, thus yielding block‐brush copolymers. The molecular weight of block‐brush copolymers was measured via triple detection GPC (TD‐GPC) introducing the experimentally calculated dn/dc values to the software. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Investigation of acetone,butanol and carbon dioxide as new breath biomarkers for convenient and noninvasive diagnosis of obstructive sleep apnea syndrome

The objective of the present study was to investigate whether analysis of carbon dioxide, acetone and/or butanol present in human breath can be used as a simple and noninvasive diagnosis method for obstructive sleep apnea syndrome (OSAS). For this purpose, overnight changes in the concentrations of these breath molecules were measured before and after sleep in 10 patients who underwent polysomnography and were diagnosed with OSAS, and were compared with the levels of these biomarkers determined after sleep in 10 healthy subjects. The concentrations of exhaled carbon dioxide were measured using external cavity laser‐based off‐axis cavity enhanced absorption spectroscopy, whereas the levels of exhaled acetone and butanol were determined using thermal desorption gas chromatography mass spectrometry. We observed no significant changes in the levels of exhaled acetone and carbon dioxide in OSAS patients after sleep compared with pre‐sleep values and compared with those in healthy control subjects. However, for the first time, to our knowledge, analyses of expired air showed an increased concentration of butanol after sleep compared with that before sleep and compared with that in healthy subjects. These results suggest that butanol can be established as a potential biomarker to enable the convenient and noninvasive diagnosis of OSAS in the future.     

Synthesis, characterization, structures and cytotoxic activity of palladium(II) and platinum(II) complexes containing bis(2-pyridylmethyl)amine and saccharinate

New palladium(II) and platinum(II) complexes containing bis(2-pyridylmethyl)amine (bpma) and saccharinate (sac), [Pd(bpma)(sac)](sac)·2H₂O (1), [Pt(bpma)(sac)](sac)·2H₂O (2), [Pd(bpma)Cl](sac)·2H₂O (3) and [Pt(bpma)(sac)]Cl·1.5H₂O (4), were synthesized and characterized by elemental analysis, IR, NMR and TG-DTA. A single-crystal X-ray analysis of 3 and 4 proved a distorted square-planar geometry around the metal ions with one tridentate bpma ligand and one Cl or sac monoanion. The [Pd(bpma)Cl]⁺ ions in 3 form dimers by intermolecular N-H?Cl and Pd?Pd interactions. The cations reside in the centers of a hydrogen-bonded honeycomb network formed by the uncoordinated sac ions and the lattice water molecules, while the cations of 4 are connected by N-H?Cl and OW-H?O hydrogen bonds into one-dimensional chains. Cyclic planar tetrameric and trimeric water clusters were observed in 3 and 4, respectively. Cytotoxicity of 1-4 was tested against A549, C6 and CHO cells. Although 2 and 4 have no cytotoxicity, the best results were achieved for 1 and 3. In particular, the cyctotoxic activity of 3 is comparable to cisplatin.     

Synthesis of novel 1,2,3-thiadizoles and 1,2,3-selenadiazoles as new antimicrobial agents

Abstract

A series of novel 1,2,3-thiadiazoles and 1,2,3-selenadiazoles having a long alkyl chain were synthesized by reacting semicarbazones with SOCl₂ and SeO₂, respectively. The structures of the target compounds 5–12 were confirmed by spectroscopy (IR, ¹H NMR, ¹³C NMR, and MS) and elemental analysis. Their antibacterial and antifungal activities were evaluated against six bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus) and three fungi (Candida albicans, Candida parapsilosis, Candida tropicalis). The results of bioassays indicated that the compounds 5-Dodecyl-4-(4-methoxy-phenyl)-[1-3]selenadiazole (7), 4-Methyl-5-tetradecyl-[1-3]selenadiazole (8) and 5-Dodecyl-4-(4-methoxy-phenyl)-[1-3]thiadiazole (11) displayed moderate antibacterial activity against S. Epidermidis. On the other hand, according to antifungal screening results, compounds 5-Dodecyl-4-phenyl-[1-3]selenadiazole (5), 4-p-Tolyl-5-undecyl-[1-3]selenadiazole (6), and 5-Dodecyl-4-(4-methoxy-phenyl)-[1-3]selenadiazole (7) exhibited significant antifungal activities studied yeast strains.     

Branching Regulation in Olefin Polymerization via Lewis Acid Triggered Isomerization of Monomers

We present a new strategy to regulate branching in chain‐walking olefin polymerization by triggering a rapid isomerization of 1‐alkene monomers into internal olefins by adding a Lewis acid. Polymerization of internal alkenes proceeds via chain‐walking to give polymers with much higher branching than 1‐alkene analogues. The utility of this approach is exemplified by synthesis of well‐defined block copolymers with distinct branching characteristics per block by addition of Lewis acid midway through a reaction. We propose a novel mechanism whereby Lewis acid undergoes a counterion swap with the complex which favors isomerization as well as forming adducts with ancillary ligands, freeing coordination sites for internal alkene coordination polymerization.