Identification of radical structures on 1‐pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide and 1,3‐bis(pentamethylbenzyl)‐4,5‐dimethylbenzimidazoliumsilver(I)bromide exposed to gamma rays: an EPR study

1‐Pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide and 1,3‐bis(pentamethylbenzyl)‐4,5dimethylbenzimidazoliumsilver(I)bromide and their Ag⁺ complexes were synthesized and their polycrystal forms were produced by recrystallization in dichloromethane/Et₂O solvent system. Structural determinations were carried out by ¹H NMR and ¹³C NMR with a Varian 400 NMR system using tetramethylsilane as internal standard and CDCl₃ as solvent. The disappearance of acidic N‐heterocyclic carbene proton showed the formation of Ag(I) complexes. Also, elemental analyses were carried out. Electron paramagnetic resonance (EPR) measurements were performed to determine the formed radical structure on the samples irradiated at the room temperature for 72 h by using ⁶⁰Co‐source with dose rate of 0.680 kGy. The EPR measurements were carried out in the temperature range of 200 K–450 K. Identical radicals were determined on the irradiated compounds. It was observed that the shapes of the spectra of the samples were independent of the temperature but, the resonance line intensities changed linearly with the temperature. Also, it was detected that the free radical on the 1‐pentamethylbenzyl‐3‐ethylimidazoliumsilver(I)bromide is not stable compared to that on the 1,3‐bis(pentamethylbenzyl)‐4,5dimethylbenzimidazoliumsilver(I)bromide. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and Antimicrobial Activities of Some 1-[(N,N-Disubstitutedthiocarbamoylthio)acetyl]-3,5-diaryl-2-pyrazolines

The increasing clinical importance of drug-resistant fungal and bacterial pathogens has lent additional urgency to microbiological research and new antimicrobial compound development. For this purpose, new pyrazoline derivatives were synthesized and evaluated for antimicrobial activity.

Some 1-[(N, N-disubstitutedthiocarbamoylthio)acetyl]-3,5-diaryl-2-pyrazolines derivatives were synthesized by reacting 1-(chloroacetyl)-3,5-diaryl-2-pyrazolines with appropriate potassium salts of secondary amine dithiocarbamic acids. The chemical structures of the compounds were elucidated by IR, ¹ H-NMR, and FAB⁺-MS spectral data. Their antimicrobial activities against Staphylococcus aureus (B-767), Escherichia coli (B-3704), Pseudomonas aeruginosa (ATCC 27853), Proteus vulgaris (NRLL B-123), and Candida albicans (NRRL-27077) were investigated. The results showed that some of the compounds have notable activity against S. aureus and C. albicans.     

Synthesis,characterization and biological evaluation of some novel sulfonylthiosemicarbazides

Abstract

A series of thiosemicarbazides were synthesized and structurally characterized by spectroscopic techniques (NMR, FT-IR) besides elemental analysis. These compounds were evaluated for their cytotoxicity against human breast cancer cell line MCF7 and prostate cancer cell line PC3 and nonmalignant fibroblast L929 cell line by MTT assay. Among the compounds, N-[2-(4-chlorophenyl)ethyl]-2-[(4-methylphenyl)sulfonyl]hydrazinecarbothioamide (3d) and 2-[(4-methylphenyl)sulfonyl]-N-[4-(trifluoromethoxy)phenyl]hydrazinecarbothioamide (3f) were found to display significant cytotoxicity with IC₅₀ of 13.87?μM (against PC3 cell line) and 1.47?μM (against MCF7 cell line), respectively. These compounds were non-cytotoxic to normal cell line with IC₅₀>100?μM. Western blotting studies demonstrated that compound 3f induced apoptosis and caused cell death in the MCF7 and PC3 cell lines via an increase in Bax protein expression and a slight decrease in Bcl-2 protein expression. The gene expression ratio Bax/Bcl-2 showed the induction of mitochondrial apoptosis in cancer cell lines. All of synthesized compounds have also been tested for antioxidant activity and all compounds achieved strong inhibition of the DPPH radical. These findings showed that compound 3f, displays potential to be further explored in the development of new anticancer agents.     

Carrier‐Mediated Transport of Hg(II) through Bulk and Supported Liquid Membranes

The transport of Hg (II) ions from an aqueous solution into an aqueous receiving solution through bulk and supported liquid membranes containing a calix[4]arene derivative 1 as a carrier was examined. The kinetic parameters of bulk liquid membrane studies were analyzed assuming two consecutive, irreversible first‐order reactions. The influence of temperature, stirring rate, carrier concentration and solvent on the kinetic parameters (k₁, k₂, R_m ^max, t_max, J_d ^max, J_a ^max) has also been investigated. The membrane entrance rate, k₁, and the membrane exit rate, k₂, increased with increasing temperature and stirring rate. The activation energy values are calculated as 4.87 and 48.63 kj mol^?1 for extraction and reextraction, respectively. The values of calculated activation energy indicate that the process is diffusionally controlled by species. Also, the transport behavior of Hg²⁺ from aqueous solution through a flat‐sheet supported liquid membrane has been investigated by the use of calix[4]arene derivative 1 as carrier and Celgard 2500 as the solid support. A Danesi mass transfer model was used to calculate the permeability coefficients for each parameter studied. The highest values of permeability were obtained with 2‐nitrophenyloctyl‐ether (NPOE) solvent and the influence was found to be in the order of NPOE>chloroform>xylene.     

Synthesis and Comparison of Extraction Properties of p‐tert‐Butylcalix[n]arene Nitrile Derivatives for Selected Metals and Dichromate Anions

The article describes the syntheses and extraction properties of two p‐tert‐butylcalix[6]arene nitrile derivatives (3 and 4). The trinitrile derivative 3 has been synthesized from 5,11,17,23,29,35‐hexa‐tert‐butyl‐37,38,39,40,41,42‐hexahydroxycalix[6]arene 1. The compound 1 was directly converted to its hexanitrile derivative 4. In these syntheses, it was thought to explore the role of nitrile sites in the extraction of various metal cations and HCr₂O₇ ^?/Cr₂O₇ ^2? anions. The liquid‐liquid extraction properties of 3 and 4 towards selected alkali/transition metal cations and HCr₂O₇ ^?/Cr₂O₇ ^2? anions are reported. It has been observed that receptor 3 does not extract alkali/transition metal cations effectively, but shows affinity towards HCr₂O₇ ^?/Cr₂O₇ ^2? anions at low pH. The compound 4 is an effective form for transferring Ni²⁺ selectively, while it shows poor transferring ability for HCr₂O₇ ^?/Cr₂O₇ ^2? anions from an aqueous into a dichloromethane layer. It was observed that the cavity size of the calix[n]arenes and the cooperativity of the functionalities play important roles in two phase extraction systems.     

Synthesis and electrochemical properties of a novel calix[4]arene derivative for facilitated transfer of alkali metal ions across water/1,2-dichloroethane micro-interface

The alkali metal ion transfers facilitated by a novel calix[4]arene derivative (OPEC) across the water/1,2-dichloroethane (1,2-DCE) micro-interface supported at the tip of a micropipette were presented. The well-defined voltammetric behaviours except Cs⁺ was obtained by cyclic voltammetry and differential pulse voltammetry. The bulk concentration of metal ions was much higher than that of OPEC in the performed measurements. The diffusion coefficient of OPEC in the 1,2-DCE phase was calculated as 5.18 ± 0.70 × 10^? 6 cm² s^? 1. On the basis of the changes of the half-wave transfer potentials, the logarithms of the association constants having 1:1 ionophore–ion complex stoichiometry for Li⁺, Na⁺, K⁺ and Rb⁺ in 1,2-DCE were determined as 4.80, 4.62, 4.98 and 5.32, respectively. The facilitated ion transfers were also evaluated by the Randles equivalent circuit used for ac-impedance data analysis.     

The Synthesis of Novel Macrocycles,Part V. The Coumarin Crown Ethers and Cation Binding with Fluorescence Spectra

Abstract

The 4-H, 4-methyl and 4-phenyl derivatives of benzo-α-pyrone of 12-crown-4 and 15-crown-5 were synthesised starting from 4-substituted-6,7-dihydroxy- and 7,8-dihydroxybenzo-α-pyrones which reacted with dichloropolyethylene glycols in DMF/water/alkali carbonate. The coumarin-macrocycles were identified by elemental analysis, IR, EI-GC-MS as well as ¹H, ¹³C NMR spectroscopy. The full experimental and spectral data is reported along with ion binding data studied in acetonitrile using fluorescence spectroscopy. The binding of the fluorogenic coumarin-crowns with Li⁺, Na⁺ and K⁺ were recognized as specific alterations on their fluorescence spectra that strongly originated from the structures. The observed CEQFS depending on the bound cation radii and macrocycle size evidenced the rules of cationic recognition of macrocycles. Some 15-crown-5 derivatives exhibited interesting Li⁺ and Na⁺ binding selectivities.     

Computational Enzyme Design

Recent developments in computational chemistry and biology have come together in the “inside‐out” approach to enzyme engineering. Proteins have been designed to catalyze reactions not previously accelerated in nature. Some of these proteins fold and act as catalysts, but the success rate is still low. The achievements and limitations of the current technology are highlighted and contrasted to other protein engineering techniques. On its own, computational “inside‐out” design can lead to the production of catalytically active and selective proteins, but their kinetic performances fall short of natural enzymes. When combined with directed evolution, molecular dynamics simulations, and crowd‐sourced structure‐prediction approaches, however, computational designs can be significantly improved in terms of binding, turnover, and thermal stability.     

The cytotoxic activities of imidazole derivatives prepared from various guanylhydrazone and phenylglyoxal monohydrate

Abstract

A series of imidazole derivatives were synthesized from two-component condensation reaction of phenylgloxal monohydrate with guanylhydrazone. They were characterized by spectroscopic and analytical techniques. The in vitro anticancer evaluation of these compounds was done on human breast cancer (MCF-7) and human liver cancer (HepG2) cell lines using the MTT assay method. Most of the newly synthesized compounds displayed cytotoxic activity against these cancerous cells. In fact, compounds 3a, 3e, and 3?h exhibited more cytotoxic activities than the positive control drugs, fluro-5, and irinocam, against the MCF-7 cell line. Almost all the compounds, except for three, 3b, 3d, and 3f, gave more cytotoxic results than cisplatin. Therefore, these compounds could be considered for further development as anticancer drug candidates.     

Synthetic Access to New Pyridone Derivatives through the Alkylation Reactions of Hydroxypyridines with Epoxides

General methods for the preparation of a variety of pyridone and oxypyridine derivatives are described. 2‐,3‐,4‐Hydroxy pyridine and 2‐pyridinemethanol were alkylated with ethylene‐, propylene‐, and stryrene‐oxide and epichlorohydrin in the presence of different Lewis acids as a catalyst. The best yield of 3a was achieved in the presence of CdI₂/BF₃ · OEt₂. The corresponding pyridone derivatives (3a–d, 7a–d) were obtained from the reaction of 2‐and 4‐hydroxypyridine with oxiranes in good yields, whereas oxypyridine derivatives (5a–d, 9a,b) were obtained from reactions of 3‐hydroxypyridine and 2‐pyridinemethanol with oxiranes. Chlorohydrines (3d, 5d, 7d) were easily converted to corresponding epoxy derivatives (10, 11, 12) in basic medium; then amino alcohols (13–17) were obtained from the reaction of these epoxy derivatives with amines.