2019

Permanent URI for this collectionhttps://hdl.handle.net/1807/92948

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Sequential Cu(II)-promoted oxidation/[3 + 2] cycloaddition/aromatization tandem reaction for the synthesis of 2-substituted benzo[f]isoindole-4,9-dione
(Canadian Science Publishing, 2019-07-31) Lin, Zhang-qi; Li, Chao-dong; Su, Jun-yi; Niu, Wen-jie; Gao, Jian-Rong; Li, Yu-jin
An efficient method for the synthesis of 2-substituted benzo[f]isoindole-4,9-dione derivatives from N-substituted iminodiacetates and quinones via a Cu(II)-promoted oxidation/[3 + 2] cycloaddition/aromatization tandem reaction was reported. This tandem reaction uses a wide range of N-substituted iminodiacetate derivatives that contain the chain-alkyl, cycloalkyl, and aryl group on the N-atom. Based on optimized reaction conditions, the desired product of 2-substituted benzo[f]isoindole-4,9-diones was obtained in moderate to excellent yields. Taken together, the promising results of this research would provide an especially efficient strategy to synthesize polysubstituted pyrroles from easy available starting materials and promoted by cheaper Cu(OAc)2.
Synthesis of a novel bruceantin analog via intramolecular etherification
(Canadian Science Publishing, 2019-12-20) Crocker, Katherine E.; Pei, Yonggang; Robertson, Erle S.; Winkler, Jeffrey D.
Reaction of the known bruceantin-derived carbinol 6 with triflic anhydride and pyridine leads to the formation of a novel hexacyclic structure 8 that results from an intramolecular etherification.
A one-pot method for the synthesis of 3-(hetero-)aryl-1,4,2-dioxazol-5-ones
(Canadian Science Publishing, 2019-12-20) Hynes, Toren; Hall, David S.; Speed, Alex; Masuda, Jason Douglas; Dahn, Jeff
3-R-1,4,2-dioxazol-5-ones are a class of compounds that are increasingly finding diverse uses, including as regioselective amidation reagents and as electrolyte additives that enable long cycling lifetimes in rechargeable lithium-ion batteries. Conventional methods for their synthesis tend to be slow and time-consuming, requiring isolation and thorough drying of a hydroxamic acid intermediate, followed by a separate cyclization step with N,N′-carbonyldiimidazole. Furthermore, the cyclization is typically performed in dichloromethane, an environmentally harmful solvent. This work demonstrates a new one-pot method for the synthesis of these compounds that eliminates the need for isolation of the intermediate or the use of halogenated solvents. The reaction is mainly performed using environmentally benign ethyl acetate and a relatively small amount of N,N-dimethylformamide. The reaction proceeds readily at room temperature and requires no expensive metal catalysts to function.
Methiin as a nematode attractant in Allium sativum
(Canadian Science Publishing, 2019-12-08) Takada, Noboru; Sutoh, Sayaka; Toyota, Masaru; Yamazaki, Yoshihisa; Kitano-Yamashita, Nozomi; Ushida, Chisato; Yamashita, Kazuo
Damage to garlic (Allium sativum) caused by nematodes Ditylenchus destructor is becoming a serious agricultural hazard, leading to a great loss in garlic production. Once the garlic bulbs are invaded, the pathogenic nematode drastically increases in number along with the rotting of bulbs. It was therefore conceived that nematode attractants are present in the bulbs. Based on this hypothesis, chemical investigations were performed to explore a nematode attractant in A. sativum bulbs, which resulted in the identification of methiin (S-methyl-L-cysteine S-oxide) as an attractant. Bioassay and quantification experiments of methiin in extracts of A. sativum bulb led to the conclusion that methiin possesses sufficient potential to attract D. destructor into A. sativum bulbs. Moreover, an activity comparing study of methiin with its analogs showed that the sulfoxide functionality is essential for attractant activity. Moreover, methiin was revealed to attract Caenorhabditis elegans. Further investigation of methiin will help to elucidate the neuronal system of D. destructor.
Synthesis of 2-(aminophenyl)adenine derivatives: a simple protocol using the classical iron powder/acetic acid reduction methodology
(Canadian Science Publishing, 2019-12-02) Rocha, Ashly; Proenca, M. Fernanda Paiva; Carvalho, Maria Alice Gonalves
2-(Nitrophenyl)adenine derivatives were isolated from the reaction of 5-amino-4-amidino-imidazoles with nitro-benzaldehydes. The conversion of the nitro derivatives to 2-(aminophenyl)adenine derivatives was performed using iron/acetic acid as reducing agent, in 70% aqueous ethanol. The products were isolated in good yield and the isolation protocol involves simple filtration and extraction procedures. This methodology is compatible with the presence of functional groups such as amines, ethers, halofluorides and halochlorides.
The chemistry of biguanides: from synthetic routes to applications in organic chemistry
(Canadian Science Publishing, 2019-12-05) Fortun, Solne; Schmitzer, Andreea
In this mini review, we focus on the chemistry and applications of biguanides. We summarize the type and preparation of biguanides, and their applications as superbases and ligands in catalysis.
Theoretical studies on the structure and properties of DAT/BTNAT cocrystal under high pressures
(Canadian Science Publishing, 2019-12-02) Li, Liangyu; Zhu, Weihua
The structural, electronic, and absorption properties of 3,5-diamino-1H-1,2,4-triazole (DAT) and 5,5â -bis (trinitromethyl) -3,3â -azo-1H-1,2,4-triazole (BTNAT) cocrystal under hydrostatic compression of 0-100 GPa were investigated by using periodic density functional theory with dispersion correction (DFT-D). The results indicate that there is structural transformation occurred at 25 GPa. The structural transformation makes the positions of the molecules rearrange in the cocrystal and improves the stability and planarity. An analysis of the band gap and density of states indicates that the DAT/BTNAT cocrystal becomes more sensitive under compression. The absorption spectra illustrates that the DAT/BTNAT cocrystal has relatively high optical activity with the increasing pressure. Our work may offer some valuable information for understanding the behavior of energetic cocrystals under high pressures.
Computational study of energetic derivatives of 3, 3′-bridged ditriazoles
(Canadian Science Publishing, 2019-11-27) Khan, Raza Ullah; Zhu, Weihua
A series of energetic bridged ditriazole was designed by incorporating different bridges and substituents into 4H-1,2,4-triazole ring. The geometrical structures, heats of formation, detonation properties, electronic structures, thermodynamic properties, free spaces, impact sensitivities, and thermal stabilities of the designed compounds were evaluated by employing density functional theory. The results elucidate that the –N3 substituent and –N=N– bridge can sufficiently increase their heats of formation. The calculated values of detonation properties show that –NF2, –ONO2, –O–, and –N=N(O)– are useful structural fragments to improve their detonation performance. The incorporation of the oxy (–O–) bridge increases their HOMO–LUMO energy gaps. An analysis of h50 values indicate that most of the designed compounds are less sensitive. The N(ring)-NO2 bond in the majority of the derivatives may be a possible trigger bond in thermal decomposition process. The incorporation of –CH2–CH2– and –O– is helpful to enhance their thermal stabilities. Based on appropriate thermal stabilities and superb detonation properties, six compounds were screened as promising high energy density compounds.
Steroids with potential anti-inflammatory activity from the roots of Datura metel L.
(Canadian Science Publishing, 2019-10-24) Liu, Yan; Guan, Wei; Yang, Chun-li; Luo, Yu-meng; Liu, Yuan; Zhou, Yuan-yuan; Liu, Li-na; Yang, Bing-you; Kuang, Hai-xue
One new C21-steroid, pregnane A (1), and two new anolides daturafolisides X and Y (2 and 3), together with six known with anolides (4–9), were isolated from the roots of Datura metel L. The structures of these compounds were established by 1D and 2D NMR spectra and mass spectroscopy by comparing our results with the literature values. Compounds 1–9 were evaluated for inhibition against nitric oxide production in lipopolysaccharide-induced RAW 264.7 macrophages. It was found that the isolated compounds showed the different levels of anti-inflammatory activities with IC50 values ranging from 24.2 to 43.4 μmol/L.
Synthesis of a Polyacrylamide Hydrogel using CO2 at Room Temperature
(Canadian Science Publishing, 2019-10-29) Ferrag, Celia; Abdinejad, Maryam; Kerman, Kagan
Carbon dioxide (CO2) is an environmentally harmful “greenhouse gas” that is present in abundant quantities in the earth’s atmosphere. Thus, the sequestration and conversion of CO2 to value-added organic chemicals is of environmental and economical importance. In this proof-of-concept study, amine groups of acrylamide compounds were found to react with CO2 under ambient conditions to form a polyacrylamide hydrogel. This composite was characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and electrospray ionization mass spectrometry (ESI–MS), which confirmed successful synthesis and demonstrated all characteristics representative of a typical hydrogel material. Rheology analyses further proved the formation of the hydrogel, as well as its self-healing nature. The novel approach proposed in this work can potentially be used in the construction of versatile amine-based gel materials for efficient CO2 utilization applications.
Enhanced removal of Eriochrome Black T in wastewater by zirconium-based MOF/graphite oxide
(Canadian Science Publishing, 2019-11-10) Bu, Jiaqi; Yuan, Lu; Ren, Yanling; Lv, Yuexin; Meng, Yong; Peng, Xin
The zirconium-based MOF/graphene oxide (UiO-66-NH2/GO) composites were prepared by ultrasonic dispersing different amounts of graphene oxide (GO) in a well-dissolved zirconium tetrachloride/H2BDC-NH2 mixture, obtaining 2 wt% (UiO-66-NH2/GO-1), 5 wt% (UiO-66-NH2/GO-2), and 10 wt% (UiO-66-NH2/GO-3) GO composites. The products were characterized by XRD, FTIR, SEM, BET, Raman, UV, XPS, and Zeta potential. Adsorption experiments on simulated Eriochrome Black T (EBT) printing and dyeing wastewater were carried out using UiO-66-NH2/GO, and the optimal conditions for adsorption were obtained by exploring the effects of initial EBT concentration, time, pH, and salt ionic strength. Adsorption isotherms, kinetics, mechanism, and regeneration were also researched. The adsorption behavior was consistent with the Langmuir isotherm and fully compliant with pseudo secondary dynamics model. The adsorption capacity of UiO-66-NH2/GO-2 was found to be the highest of the three products, which was 263.158 mg/g. Therefore, the UiO-66-NH2/GO-2 composite was considered to be an excellent adsorbent for the adsorption of EBT from organic dye wastewater.
Carbon nanotubes and carbon fibers in a flash: an easy and convenient preparation of carbon nanostructures using a conventional microwave
(Canadian Science Publishing, 2019-10-14) Veloz-Castillo, María Fernanda; Paredes-Arroyo, Antonio; Vallejo-Espinosa, Gerardo; Delgado Jimenez, Jose Francisco; Coffer, Jeffery L; Gonzalez-Rodriguez, Roberto; Mendoza, María Eugenia; Campos-Delgado, Jessica; Mendez-Rojas, Miguel Angel
The growing interest in nanomaterials in different application fields calls for the implementation of simple, economically appealing, and efficient preparative methods. Among the wide variety of nanomaterials, carbon nanostructures have a special place due to their potential technological applications. Here, we present a fast, cheap, and easy-to-implement microwave-assisted method for the preparation of carbon nanotubes (CNTs) and carbon fibers (CFs) at room pressure conditions. The synthesis involves heating a mixture of graphite and ferrocene contained in a simple glass tube using a conventional microwave oven. A mixture of multi-walled carbon nanotubes (MWCNTs) and Fe3O4 magnetic nanoparticles were obtained quickly (less than 30 s) and in good yields. The products were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Raman spectroscopy.
A Three-step Sequence Strategy for Facile Construction of Donor-Acceptor Type Molecules: Triphenylamine-Substituted Acenes
(Canadian Science Publishing, 2019-10-01) Zhang, Chen; Tang, Ming; Sun, Bing; Wang, Weizhou; Yi, Ying; Zhang, Fang-Lin
A new synthetic strategy was successfully developed for highly efficient construction of triphenylamine-substituted polycyclic aromatic hydrocarbons (PAHs), including anthracenes, tetraphenes, pentaphenes and trinaphthylene. These molecules exhibited special structural characteristics, including donor-acceptor-donor (D-A-D) and donor-acceptor (D-A). Diverse aryl iodides coupled well with chlorinated 2-methyl benzaldehydes via a transient ligand-directed Câ H bond arylation strategy to furnish various PAH precursors. The subsequent palladium-catalyzed Suzuki cross-couplings with 4-(diphenylamino)phenylboronic acid produced corresponding triphenylamine derivatives. Further BrĂ¸nsted acid-promoted cycloaromatization generated the triphenylamine-substituted PAHs readily. The photophysical properties was investigated by UV-visible absorption and fluorescence emission spectroscope together with density functional theory (DFT) calculations.
Synthesis, physical characterization, antifungal and antibacterial activity of oleic acid capped nanomagnetite and cobalt-doped nanomagnetite
(Canadian Science Publishing, 2019-10-14) Rahdar, Abbas; Beyzaei, Hamid; Saadat, Mohsen; Yu, Xiao; Trant, John
Nanoparticles, 10-14 nm, consisting of either Fe3O4 or Co0.2Fe2.8O4 stabilized with oleic acid, were prepared using solution combustion. Their structural and magnetic properties were examined using X-ray diffractometry, scanning electron microscopy, vibrating sample magnetometry, and Fourier-transform infrared spectroscopy. The properties of both sets of materials are similar except the cobalt-doped particles are considerably less magnetic. The in vitro inhibitory activities of the nanoparticles were assessed against pathogenic bacteria Shigella dysenteriae, Klebsiella pneumoniae, Acinetobacter baumannii, Streptococcus pyogenes, and pathogenic fungi and molds Candida albicans, Fusarium oxysporum and Aspergillus fumigatus. The magnetite nanoparticles were moderately effective against all tested pathogens, but the activity of the cobalt-doped nanoparticles was significantly lower, possibly due to an interruption of the Fenton reaction at the bacterial membrane. This work suggests that potentially doping magnetite with stronger metal oxidants may instead enhance their antimicrobial effects.
Photoionization microscopy of the Rydberg Rb atom under a continuous infrared radiation laser field
(Canadian Science Publishing, 2019-10-10) Wang, Dehua; Sun, Xinyue; Shi, Tong
The photoionization microscopy of the Rydberg Rb atom exposed to a continuous infrared radiation laser field is investigated based on the semiclassical open orbit theory. In contrast to the photoionization of the Rydberg hydrogen atom, the ionic core-scattering effect plays an important role in the photoionization of the Rb atom. Due to the core-scattering effect and the laser field, the electron trajectories become chaotic. A huge number of ionization trajectories from the ionic source to the detector plane appear, which makes the oscillatory pattern in the electron probability distribution become much more complicated. The ρ–θ curve on the detector plane exhibits a self-similar fractal structure for the ionization trajectories of the Rydberg Rb atom in the laser field. Due to constructive and destructive quantum interference of different electron trajectories, a series of concentric rings appear in the photoionization microscopy interference patterns on the detector plane. The electron probability density distributions on the detector are found to be changed sensitively with the scaled electron energy and the laser wavelength. Even as the detector plane is located at a macroscopic distance from the photoionization source, the photoionization microscopy interference patterns can be observed clearly. These calculations may provide a valuable contribution to the actual experimental study of the photoionization microscopy of non-hydrogenic Rydberg atom in the laser field.
Formative assessments using text messages to develop students’ ability to provide causal reasoning in general chemistry
(Canadian Science Publishing, 2019-10-12) Sweeder, Ryan David; Herrington, Deborah G.
Formative assessment is critical in providing students the opportunity to self-assess their content knowledge and providing data to inform instructional decisions. It also provides students with information about course expectations. If, as called for in numerous science instruction reform efforts, we expect students to be able to apply their chemistry knowledge to analyze data and construct coherent explanations, then not only must summative assessments include items that require this of students, but students must also be provided with frequent and ongoing opportunities to individually practice this difficult task and receive feedback. Although online homework systems can be quite effective at providing students with feedback regarding their mastery of basic skills, it is typically less useful in providing meaningful feedback on constructed student explanations. This study examined the impact of providing students with frequent out-of-class formative assessment activities initiated by text messages. Student responses were then used to facilitate in-class instruction. Increased student participation in these formative assessment tasks correlated positively with success on exams even after accounting for student prior knowledge. There was also evidence that students increased their ability to construct complete explanation over the course of the semester. All results were consistent across two different institutions and three instructors.
Detecting and imaging of SO2 derivatives in living cells with zero cross-talk colorimetric mitochondria-targeted fluorescent probe
(Canadian Science Publishing, 2019-09-01) Wu, Dan; Rong, Shiqi; Liu, Yi; Zheng, Fei; Zhao, Yankun; Yang, Ruiwu; Du, Xiaogang; Meng, Fengyan; Zou, Ping; Wang, Guangtu
It is well known that excessive levels of sulfur dioxide and its derivatives are con-nected to diverse diseases. Therefore, developing highly sensitive probes to detect and monitor sulfite in living cells is important for the diagnosis of disease and the study of biochemical processes in vivo. In this report, two zero cross-talk ratiometric fluorescent probes were synthesized (CA-ID-MC and CA-BI-MC), which were de-rived from carbazole-indolenine Ď -conjugated system for effective detection of sul-fite in living cells. Observably, CA-BI-MC exhibited the largest emission shift of 157 nm from 617 to 460 nm with the addition of various concentrations of sulfite, which is beneficial for high-resolution imaging of the sulfite. CA-BI-MC also exhibits high sensitivity, as well as low cytotoxicity. More importantly, this probe successfully located mitochondria and sensed the sulfite in HeLa cells caused by exogenous stimulation.
Investigations of the formation of zeolite ZSM-39 (MTN)
(Canadian Science Publishing, 2019-08-16) Lin, Zheng Sonia; Chen, Donghan; Nie, Heng-Yong; Wong, Y. T. Angel; Huang, Yining
Crystallization of zeolite ZSM-39 (MTN), a clathrate and silicate analogue of the 17 Å cubic gas hydrate, was examined in a solvent system involving a tetramethylammonium chloride – 1,6-hexanediol deep eutectic mixture and significant amount of water. The crystallization process was followed by powder X-ray diffraction (PXRD), and solid-state nuclear magnetic resonance (SSNMR) techniques involving several nuclei such as 19F, 29Si, and 13C. The results indicate that the crystallization starts from the arrangement of amorphous Si–O–Si species around the tetramethylammonium ions and subsequent formation of the cages in the precursors similar to [51264] cages in the MTN topology. The larger [51264] cages are then connected via the smaller [512] cages containing the fluoride ions to form the final MTN structure. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses show that the crystal growth rates along <100> and <111> directions are roughly the same, suggesting that the (100) and (111) planes have similar stability under the crystallization conditions used. AFM study also shows that the freshly born nuclei on the (100) face are of a height of 2 nm, suggesting a layer by layer growth of the polyhedral crystal.
Synthesis, characterization, and investigation of the antioxidant activity of some 1,2,4-benzothiadiazine-1,1-dioxides bearing sulfonylthioureas moieties
(Canadian Science Publishing, 2019-08-12) Harrouche, Kamel; Lahouel , Asma; Belghobsi, Mebrouk; Pirotte, Bernard; Khelili, Smail
A series of 1,2,4-benzothiadiazine-1,1-dioxides bearing a sulfonylthiourea moiety were synthesized, characterized, and screened for their antioxidant activity, using six antioxidant analytical assays comparatively to reference compounds, ascorbic acid and quercetin. The results indicated that several compounds demonstrated strong antioxidant activity in DPPH, ABTS, H2O2, and lipid peroxidation assays where some of them were either as active as or more active than reference compounds. However, all compounds were largely less active than references compounds in the reducing power assay. The results indicated that the thiourea moiety probably played a crucial role in the antioxidant activity of the target compounds, as a thiolate ion. The most favorable R1 groups were the hydrogen atom and methyl group, followed by phenyl and benzyl groups, whereas the most favorable R2 group was iPr, followed by the phenyl and methyl groups. The combination of benzothiadiazine ring with sulfonylthiourea moieties led to valuable new antioxidants, which could be used in the treatment or the prevention of certain diseases or in the field of cosmetics, which needs further investigations in the future.
Electrochemical sensor based on incorporation of gold nanoparticles, ionic liquid crystal, and β-cyclodextrin into carbon paste composite for ultra-sensitive determination of norepinephrine in real samples
(Canadian Science Publishing, 2019-07-08) Atta, Nada F.; Galal, Ahmed; El-Said, Dalia M
A novel, reliable electrochemical sensor is fabricated for direct and sensitive determination of norepinephrine (NE) based on gold nanoparticles, ionic liquid crystal, and β-cyclodextrin modified carbon paste electrode, namely AuILCCDCPE. The ionic liquid crystal (ILC) played a key role in improving the current response of electro-oxidation of NE compared with other ionic liquids modified electrodes. The ILC increased the ionic conductivity of the paste and formed noncovalent interactions with both host (CD) and guest (NE) compounds. The solid state structure of the ILC helped in the formation of ordered films in the paste. Furthermore, CD and Au nanoparticles raised the stability and the electrocatalytic ability of the proposed sensor. Under optimized conditions, the fabricated electrochemical sensor showed a good electrochemical response towards NE in human urine in the linear dynamic ranges of 0.05–10 μmol/L and 20–300 μmol/L with a correlation coefficient of 0.999 and detection limit of 3.12 × 10−9 mol/L in the low concentration range. The practical analytical performance of the sensor was attained for determination of NE in real samples with satisfied recovery results. This sensor has great ability to be extended for electrochemical applications in assays of other drugs.

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