Voltammetric and Docking Investigation of the Binding Interaction between (E)-1-[(2-Phenoxyphenylimino)methyl]naphthalen-2-ol and Calf Thymus DNA

Russian Journal of Electrochemistry - In vitro interaction between (E)-1-[(2-phenoxyphenylimino)methyl]naphthalen-2-ol (2-PPMN) and calf thymus DNA (ct-DNA) at physiological pH was investigated by...     

ABC type miktoarm star copolymers through combination of controlled polymerization techniques with thiol‐ene and azide‐alkyne click reactions

ABC type miktoarm star copolymer with polystyrene (PS), poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) arms was synthesized using controlled polymerization techniques in combination with thiol‐ene and copper catalyzed azide‐alyne “click” reactions (CuAAC) and characterized. For this purpose, 1‐(allyloxy)‐3‐azidopropan‐2‐ol was synthesized as the core component in a one‐step reaction with high yields (96%). Independently, ω‐thiol functionalized polystyrene (PS‐SH) was synthesized in a two‐step protocol with a very narrow molecular weight distribution. The bromo end function of PS obtained by atom transfer radical polymerization was first converted to xanthate function and then reacted with 1, 2‐ethandithiol to yield desired thiol functional polymer (PS‐SH). The obtained polymer was grafted onto the core by thiol‐ene click chemistry. In the following stage, ε‐caprolactone monomer was polymerized from the core by ring opening polymerization (ROP) using tin octoate as catalyst through hydroxyl groups to form the second arm. Finally, PEG‐acetylene, which was simply synthesized by the esterification of Me‐PEG and 5‐pentynoic acid, was clicked onto the core through azide groups present in the structure. The intermediates at various stages and the final miktoarm star copolymer were characterized by ¹H NMR, FTIR, and GPC measurements. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Investigating the Effect of Chewing Force and an Abrasive Medium on the Wear Resistance of Composite Materials by Chewing Simulation

Mechanics of Composite Materials - Various composite materials used as biomaterials were tested by 20-, 50-, and 80-N chewing forces in distilled water and a poppy seed medium by using a...     

Optimization of the synthesis of het/aryl-amidoximes using an efficient green chemistry

Abstract

This work focuses on optimizing an efficient green synthesis of arylamidoximes from appropriate nitrile and hydroxylamine hydrochloride in water and triethylamine (1.6?mol equivalent) as a base at room temperature for 6?h. This new green synthetic methodology is compared with previously known methods. The main advantages of this new process reported are good yield, easier work-up and short reaction times. Moreover, some of the synthesized arylamidoximes converted to 1,2,4-oxadiazole derivatives 13a,b and 14 via the reaction with (4-acetylphenoxy)acetic acid 12.     

Silica Gel-Immobilized 5-aminoisophthalohydrazide: A novel sorbent for solid phase extraction of Cu,Zn and Pb from natural water samples

A novel silica sorbent, silica gel-immobilized 5-aminoisophthalohydrazide (SiO₂-APH), was prepared by the condensation of 3-chloropropyl-functionalized silica gel with 5-aminoisophthalohydrazide (APH) derived from dimethyl 5-aminoisophthalate as a starting material and used for separation and preconcentration of Cu, Zn, and Pb metals in water samples using Flame Atomic Absorption Spectrometry (FAAS). The characterization of the new sorbent was carried out by Elemental Analysis, Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). Important analytical parameters including as pH, amount of sorbent, type and amount of eluting solvent, sample volume, vortex and ultrasonic bath time, matrix ions that effect the developed SiO₂-APH-solid phase extraction (SPE) method were investigated and optimum parameters were detected. Recoveries of examined metals were obtained as 98% for Cu and Pb and 101% for Zn. The relative standard deviation (RSD, n = 8) of Cu, Zn and Pb metals were 3.2, 2.8 and 1.6%, respectively. Limit of detections (LODs) (n = 10) were found as 2.7 μg L⁻¹ for Cu, 7.4 μg L⁻¹ for Zn and 3.5 μg L⁻¹ for Pb μg L⁻¹. The accuracy of the new method was assessed by analyzing of TMDA-51.4 and TMDA-70.2 certified reference materials. The results obtained for metals were in a good agreement with certified values. Addition/recovery test was applied to the real well, river, dam and stream water samples to check the accuracy of the method. The results showed that the developed SiO₂-APH-SPE method can be effectively used as an alternative method for determination of Cu, Zn, and Pb metals in water samples.     

Preparation of Calix[4]arene Alkylamine Derivatives by Mannich Reaction and use as Phase-Transfer Catalysts for Esterification Reaction

In this study, 5,11,17,23-tetrakis[(N-ethylpiperazine)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (3) and 5,11,17,23-tetrakis[(4-carboethoxy-N-piperidino) methyl]-25,26,27,28-tetrahydroxycalix[4]arene (4) were synthesized in one step according to the Mannich reaction by the treatment of calix[4]arene with a secondary amine (N-ethylpiperazine, ethyl-4-piperidincarboxylate) and formaldehyde. The calix[4]arene derivatives (3, 4) were characterized by a combination of FTIR, ¹H NMR and elemental analyses. The synthesized compounds were used in an esterification reaction as the phase transfer catalyst. The catalytic efficiency of the calix[4]arenes 3 and 4 was evaluated by carrying out the ester-forming reaction of alkali metal carboxylates (sodium butyrate or sodium caprylate) with p-nitrobenzyl bromide. It was observed that the ester-forming reaction of alkali metal carboxylates with p-nitrobenzyl bromide, using calix[4]arene-based catalyst 3 as a phase-transfer catalyst in dichloromethan, provided the best yields.     

Synthesis of 4,4′-biquinazoline alcohols as chiral catalysts in enantioselective alkynylation of aldehydes with phenyl acetylene

Optically active propargylic alcohols are important chiral-building blocks in asymmetric synthesis, while the asymmetric addition of a terminal alkyne to an aldehyde is one of the most important procedures to prepare these chiral-building blocks. In this work, a family of chiral 4,4′-biquinazoline alcohols has been conveniently prepared from the easily accessible (S)-2-acetoxycarboxylic acid chlorides by reaction sequences beginning with condensation and followed by key synthetic steps including chlorination, nickel(0)-mediated homocoupling, and deprotection in addition to being examined as potential ligands in the enantioselective addition of phenylacetylene to aldehydes. These chiral ligands can be combined with Ti(OiPr)₄ and then used to catalyze the asymmetric addition of zinc acetylide, produced in situ by the reaction of phenylacetylene with diethylzinc, to aldehydes. The best enantiomeric excess obtained in this study was 75%.     

Equality of averaged and quenched large deviations for random walks in random environments in dimensions four and higher

We consider large deviations for nearest-neighbor random walk in a uniformly elliptic i.i.d. environment. It is easy to see that the quenched and the averaged rate functions are not identically equal. When the dimension is at least four and Sznitman??s transience condition (T) is satisfied, we prove that these rate functions are finite and equal on a closed set whose interior contains every nonzero velocity at which the rate functions vanish.     

The performance,emissions, and combustion characteristics of an unmodified diesel engine running on the ternary blends of pentanol/safflower oil biodiesel/diesel fuel

Journal of Thermal Analysis and Calorimetry - The objective of the present study is to scrutinize the influence of a binary blend of diesel–safflower oil biodiesel and ternary blends of...