Organic Communications Articles
Issue: 3 July-September
Year: 2017 Volume: 10 Issue:3 July-September
1) GAP pre-polymer, as an energetic binder and high performance additive for propellants and explosives: A review
In preparation of energetic composite formulations, functionally terminated pre-polymers have been used as binder. After physically mixing the pre-polymers with oxidizing components, metallic fuel, burning rate modifier and other minor ingredients, they are cured with a suitable curing agent to provide physical and chemical stability. These pre-polymers could be functionalized with carboxyl, epoxide or hydroxyl groups at varying average chain functionalities. For carboxyl-terminated pre-polymers, an epoxy functional curing agents could be used. If the pre-polymer possesses hydroxyl groups, isocyanate functional curing agents are the most suitable curing agents in terms of easy and efficient processing. Glycidyl azide polymer (GAP) is one of the well-known low-molecular weight energetic liquid pre-polymer, which was developed to use as energetic binder, high performance additive and gas generator for high performance smokeless composite propellant and explosive formulations. Linear or branched GAP can be synthesized by nucleophilic substitution reaction of corresponding poly(epichlorohydrin) (PECH) with sodium azide through replacement of chloromethyl groups of PECH with pendant energetic azido-methyl groups on the polyether main chain. Positive heat of formation (+957 kJ/kg) enables exothermic and rapid decomposition of GAP producing fuel rich gases. Its polyether main chain provides GAP with relatively low glass transition temperature (Tg= - 48 oC) and presence of hydroxyl functional groups allows it to have easy processing in curing with isocyanate curing agents to form covalently crosslinked polyurethane structure. These outstanding properties of GAP enable it to be used as energetic polymeric binder and high performance additive in preparation of energetic materials and low vulnerable explosives.DOI http://doi.org/10.25135/acg.oc.21.17.07.038 Keywords GAP glycidyl azide polymer PGA polyglycidyl azide energetic materials DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
2) Synthesis and NMR characterization of dendrimers based on 2, 2-bis-(hydroxymethyl)-propanoic acid (bis-HMPA) containing peripheral amino acid residues for gene transfection
Dendrimers, the emerging man made, highly branched, star-shaped macromolecules with nanometer-scale dimensions are well known for their well defined and high controlled architecture, their versatility and high functionality and are of eminent interest in nanomedical applications such as drug delivery, gene transfection, and imaging. In this paper, versatile protocols for the synthesis of polyester-based, hydrolysable, polycationic dendrimers have been setup. A fourth generation dendrimer equipped with 48 peripheral hydroxyl groups was prepared from 2,2-bis(hydroxymethyl)propanoic acid and was used for grafting BOC-amino acids or as “hypercores” on which dendrons functionalized with BOC-amino acids were attached. A library of 15 polycationic homo- and hetero-dendrimers in the form of hydrochloride was obtained. Their structures and composition were confirmed by NMR analysis and by experimental molecular weight computed by volumetric titration. Their buffer capacity and results obtained from cytotoxicity assays and tests of binding with both pDNA and siRNA were very satisfactory.DOI http://doi.org/10.25135/acg.oc.22.17.06.034 Keywords Polyester-based polycationic dendrimers 2 2-bis(hydroxymethyl)propanoic acid amino acids p DNA and siRNA binding buffer capacity DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
3) Regioselective synthesis and preliminary cytotoxic activity properties of tetrazole appendage N-substituted piperazine derivatives
A series of 1-(4-substituted)-4-(3-((1-(substituted)-1H-tetrazol-5-yl)thio)propyl)piperazine derivatives were ( 6a-t) synthesized by KF-Al2O3 mediated S-alkylation of 5-thio-substituted tetrazole with 1-(3-chloropropyl)-4-(4-substituted)piperazine. The structures of the newly synthesized compounds were characterized by NMR and MS spectral data. Further, the regioselective formation of C-S bond was unambiguously confirmed by single crystal X- ray diffraction. All the synthesized compounds were screened for their in vitro cytotoxic activities against two cancer cell lines: DU-145 (prostate cancer) and HeLa (cervical cancer). These cell lines were utilized in MTT assays and the obtained results were compared to doxorubicin, and their IC 50 values were determined. Among the compounds tested, 6f, 6j, 6m, 6n, 6o, 6q, 6r and 6t showed considerable potent activity, while the compound 6p exhibited significant potent activity against DU-145 and HeLa cancer cell lines compare to standard Doxorubicin.
DOI http://doi.org/10.25135/acg.oc.20.17.04.018 Keywords Tetrazole cytotoxic activity piperazine DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
4) Synthesis, characterization, in vitro antiproliferative and cytotoxicity effects of a new class of 2-((1R,2S)-2-((E)-4-substitutedstyryl) cyclooctyl)benzo[d]thiazole derivatives
The novel 2-((1R,2S)-2-((E)-4-substitutedstyryl) cyclooctyl)benzo[d]thiazole s(12-14)were synthesized from the reaction of 10-(4-substitutedbenzylidene)bicyclo[6.2.0]decan-9-ones (5a-8a) with 2 -aminothiophenol (11) in the presence ofp -TsOH at reflux conditions in good yields. The antiproliferative activities of 12-14 were determined againts C6 (rat brain carcinoma) and HeLa (human cervical carcinoma) cell lines using BrdU cell proliferation ELISA assay. 5-Fu (5-fluorouracil) was used as standard. The antiproliferative activities of 12-14 and the control were investigated on eight concentrations (5, 10, 20, 30, 40, 50, 75 and 100 µM). The results showed that the synthesized compounds had significant antiproliferative activity and low cytotoxicity effects.DOI http://doi.org/10.25135/acg.oc.18.17.02.009 Keywords Benzothiazole anticancer cytotoxicity HeLa C6 DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
5) Unsymmetrical urea and thiourea derivatives: An efficient nano BF 3-SiO 2 catalyzed PEG-400 mediated sonochemical synthesis and biological evaluation
An efficient and green approach has been developed for the synthesis of (substituted phenyl)-3-(4-(4-nitrophenylthio)phenyl)urea/thiourea derivatives 6(a-j) using non-hazardous green solvent, PEG-400 under ultrasound irradiation conditions in the presence of a reusable silica-supported Lewis acid catalyst, nano-BF 3-SiO 2via simple addition reaction of 4-(4-nitrophenylthio)aniline (4) with substituted phenyl isocyanates/isothiocyanates 5 (a-j). The advantages of developed method are convenient, offered higher yield of products with purity, less reaction time, easy work-up and reusability of the catalyst. Structures of the title products were established by IR, NMR ( 1H, 13C), mass spectral data and elemental analysis. Antimicrobial activity of the newly synthesized compounds was tested and the bio-screening data disclosed that urea derivatives, 6a and 6d, and thiourea derivatives, 6f, 6i and 6j showed potential antimicrobial activity against the growth of selected microorganisms.DOI http://doi.org/10.25135/acg.oc.188.8.131.525 Keywords 4-(4-Nitrophenylthio)aniline nano-BF 3.SiO 2 PEG-400 ultrasonication urea and thiourea derivatives antimicrobial activity DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
6) Design, preparation and application of a Pirkle-type chiral stationary phase for enantioseparation of some racemic organic acids and molecular dynamics studies
This study consists of two parts. In the first part of the study; a Pirkle-type chiral stationary phase was prepared by synthesizing an aromatic amine derivative of (R)-2-amino-1-butanol as a chiral selectorand binding to L- tyrosine -modified cyanogen bromide (CNBr)-activated Sepharose 4B and then, packed into the separation column. T he chromatographic performance of the separation column was evaluated w ith racemic mandelic acid and 2-phenylpropionic acid by using phosphate buffers at three different pHs as mobile phase. In the resolution processes, t he prepared solutions were loaded onto the separation column at two different concentrations and at three different pHs for each racemic organic acid, separately. Enantiomeric excess (ee % ) of the eluates was determined on CHIRALPAK AD-H chiral analytical column by HPLC. The maximum ee% for mandelic acid and 2-phenylpropionic acid was determined to be 60.84 and 27.4, respectively. Separation factors (k 1 ’, k 2 ’, α, and Rs) were calculated for each acid. The structures of the obtained compounds were characterized using the spectroscopic methods (NMR, and elemental analysis). In the second part of the study; enantioselective interactions between the prepared CSP and the analytes have been widely studied by docking, molecular dynamics simulation and quantum mechanical computation methods. The reason of column eluation of rac-2-phenylpropionic acid with lower enantiomeric yield was explained by these techniques.DOI http://doi.org/10.25135/acg.oc.25.17.07.037 Keywords Pirkle-type chiral stationary phase enantioseparation molecular dynamics docking DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
7) Synthesis and biological activities of piperazine derivatives as antimicrobial and antifungal agents
Apart from thiazole, benzimidazole, and tetrazole family, some of the piperazine analogs also show significant pharmacophoric activities. The synthesis of piperazine through intermediate 3 occurred via coupling of substituted benzenethiol with chloro-nitrobenzene. The nitro group of the isolated intermediate was reduced via an iron-acetic acid system. The aniline intermediate was cyclized with bis(2-chloroethyl)amine hydrochloride to obtain piperazine moiety. The synthesized substituted piperazine derivatives were screened for antibacterial and antifungal activities. The antibacterial activity was tested against Staphylococcus aureus, Streptomyces epidermidis, Pseudomonas aeruginosa and Escherichia coli, and antifungal activity was tested against Candida albicans, Aspergillus niger, Aspergillus flavus and Aspergillus fumigatus. As a result, many of the synthesized compounds showed significant antimicrobial and antifungal properties.DOI http://doi.org/10.25135/acg.oc.23.17.05.026 Keywords Antibacterial activity antifungal activity piperazine derivatives DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.
8) Design, synthesis, spectral characterization and bioactivity evaluation of new sulfonamide and carbamate derivatives of 5-Nitro-1H-indazole
A series of new sulfonamide and carbamate derivatives of 5-nitro-1H-indazole was synthesized in good yields. The structures of all the newly synthesized compounds were confirmed by IR, 1H, 13C-NMR, Mass spectra and elemental analysis. The compounds 9a and 9f showed high antibacterial activity against L. bacillus and S. aureu, 9f and 9j exhibited good activity against E. coli and P. florescensa, whereas the compounds 9a, 9d. 9f and 9j showed good antifungal activity against tested fungal strains, however, compared to all the compounds 9e and 9h exhibited significant activity against A. niger and P.chrysogenum respectively.DOI http://doi.org/10.25135/acg.oc.24.17.05.023 Keywords 5-Nitroindazole sulfonamides carbamates antimicrobial activity DETAILS PDF OF ARTICLE © 2017 ACG Publications. All rights reserved.