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Canadian Journal of Chemistry
Journal Prestige (SJR): 0.29

Citation Impact (citeScore): 1
Number of Followers: 11

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0008-4042 - ISSN (Online) 1480-3291
Published by NRC Research Press

[19 journals]

Crudden culture
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  Authors: Stephanie MacQuarrie, Christene Smith, Megan Bruce
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-24T07:00:00Z
  DOI: 10.1139/cjc-2023-0023
Massively parallel fragment-based quantum chemistry for large molecular
systems: the serestipy software
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  Authors: Patrick Eschenbach, Niklas Niemeyer, Johannes Neugebauer
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  We present the Serestipy software as an add-on to the quantum-chemistry program Serenity. Serestipy is a representational-state transfer-oriented application programming interface written in the Python programming language enabling parallel subsystem density-functional theory calculations. We introduce approximate strategies in the context of frozen-density embedding time-dependent density-functional theory to make parallel large-scale excited-state calculations feasible. Their accuracy is carefully benchmarked with calculations for a model system consisting of porphine rings. We apply this framework to a nanotube made up of those porphine rings consisting of 12 160 atoms (or 264 960 basis functions) and obtain its electronic structure and absorption spectrum in less than a day of computational time.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-18T07:00:00Z
  DOI: 10.1139/cjc-2022-0243
Dopamine delivery systems based on C60 and C24 with B and N as
substituents
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  Authors: Ana Martínez
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Two different options as potential dopamine delivery systems were investigated in this study: fullerene C60- and C24-like structures. The systems being investigated include C60, C59X, C58X2, C24, C23X, and C22X2 (X represents B or N). Electron donor acceptor capacity and interaction energies were reported. Systems with one B are better electron acceptors than those with one N. The interaction of compounds containing B with dopamine is more favorable than the interaction of systems containing N. For a dopamine delivery system, at least two conditions are necessary. The first is the stability of the carrier-dopamine compound. This condition is fulfilled because C60-based heterofullerenes with B and dopamine form stable structures. Also, dopamine with C24-based structures containing B or N form stable structures. The second is that the interaction energy should be lower than the energy that binds dopamine to the receptor. Systems that fulfill the second condition include C60 and C58B2. The other systems present interaction energies that exceed 40 kcal/mol. Dopamine will bond to these systems and will most probably not be delivered at the receptor site, but these systems that interact strongly with dopamine may serve as agonists because they are good electron donors like dopamine. Systems with B could be antagonists of dopamine since they are good electron acceptors. This idea might be interesting to explore through experiments because heterofullerenes with B and dopamine might serve as antipsychotics rather than dopamine delivery systems.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-17T07:00:00Z
  DOI: 10.1139/cjc-2022-0234
Micro-to-macroscaling of DFT-calculated IR spectra for spectrum-feature
extraction and estimation of dielectric response
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  Authors: Samuel G. Lambrakos, Andrew Shabaev, Sonjae Wallace, Lou Massa
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Extraction of experimental spectrum features from target molecules, for purpose of their detection, can be achieved by comparison to template spectra within a database. This study continues presentation of the concept of using density functional theory (DFT). DFT-calculated spectra are well posed for comparison to measured spectra, to the extent of their scalability to larger space–time scales. Specifically, the focus of this study is the scalability of DFT-calculated IR spectra with respect to meso- and macroscales, characteristic of dielectric response as measured using different IR spectroscopies. A case-study analysis concerning IR spectra scalability for caffeine is described. Caffeine is only used as an example of analysis that can be applied to PFAS molecules, which are our major interest.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-16T07:00:00Z
  DOI: 10.1139/cjc-2023-0018
Efficient simulation of multielectron dynamics in molecules under intense
laser pulses: implementation of the multiconfiguration time-dependent
Hartree–Fock method based on the adaptive finite element method
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  Authors: Yuki Orimo, Takeshi Sato, Kenichi L. Ishikawa
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  We present an implementation of the multiconfiguration time-dependent Hartree–Fock method based on the adaptive finite element method for molecules under intense laser pulses. For efficient simulations, orbital functions are propagated by a stable propagator using the short iterative Arnoldi scheme and our implementation is parallelized for distributed memory computing. This is demonstrated by simulating high-harmonic generation from a water molecule and achieves a simulation of multielectron dynamics with overwhelmingly less computational time, compared to our previous work [Sawada, R. et al. Phys. Rev. A, 2016, 93, 023434].
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-12T07:00:00Z
  DOI: 10.1139/cjc-2022-0280
The prospects of cation transfer to chalcogen nucleophiles
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  Authors: Bun Chan, Seiji Shirakawa
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  In this study, we used computational quantum chemistry to investigate the cation affinity for a range of nucleophiles to gauge the possibility of using organochalcogens as catalysts for cation transfer (reference data and geometries are provided in the repository https://github.com/armanderch/ca176). In general, the calculated gas-phase cation affinities decrease in the order Cl+> Br+> I+> carbon-centered cation, the anionic nucleophiles have significantly larger cation affinities than the neutral ones, sulfides have larger cation affinities than selenides, and solvation lowers the cation affinities and especially for anionic nucleophiles. These observations are consistent with general chemical intuitions. The energies for the resulting condensed-phase cation transfer reactions show that transferring a carbon-centered cation from a neutral source (e.g., Me2CO3) to a chalcogen nucleophile (e.g., Me2S) is thermochemically viable. However, they are associated with large kinetic barriers. Overall, we find that SeMeC6H5 may be a suitable catalyst for transferring a carbon-centered cation from an active source such as MeCO3R or MeSO4R. In this study, we also find that double-hybrid DFT methods, e.g., DSD-PBEP86 to be reasonable for the study of these cation transfer processes.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-11T07:00:00Z
  DOI: 10.1139/cjc-2022-0222
Generation of copper fluoroalkyl complexes (CuRFLn) from
chlorotrifluoroethylene and −RF transfer to aroyl chlorides
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  Authors: Luana L.T.N. Porto, Moutasem Seifi, Nicole Johnson, R. Tom Baker
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Given the importance of fluorinated drugs and agrochemicals, fluoroalkylation of organic electrophiles that can be performed at a late stage of chemical synthesis has attracted a flurry of contributions. New fluoroalkyl groups can be obtained by insertion of fluoroalkenes into Cu–H bonds. Chlorotrifluoroethylene undergoes regioselective insertion in its reaction with Stryker's reagent, [CuH(PPh3)]6 and triphos to give [Cu(CFClCF2H)(μ−κ1,κ2-triphos)]2, which mediates the fluoroalkylation of several aroyl chlorides (triphos = bis(2-diphenylphosphinoethyl)-phenylphosphine). In contrast, attempted −RF transfer to aryl iodides instead affords aryl–aryl coupling products.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0240
Synthesis and characterization of tetraphenylethylene-functionalized
N-heterocyclic carbene-stabilized gold nanoparticles with
aggregation-induced emission
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  Authors: Marilyne Bélanger-Bouliga, Nadjib Kihal, Hanae Mahious, Phuong Trang Nguyen, Steve Bourgault, Ali Nazemi
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Gold nanoparticles (AuNPs) have found use in broad range of applications such as in catalysis and nanomedicine. Despite the fact that thiol-based AuNPs have been widely studied, they suffer from relative instability in various conditions, such as high and low temperatures, pH variations, and are prone to oxidation. Over the last decade, N-heterocyclic carbenes (NHCs) have been under spotlight as suitable ligands to stabilize metal nanoparticles and surfaces. Although NHC-functionalized AuNPs have been shown to outperform their thiol-based analogs in terms of stability, their applications in nanomedicine have not been realized. Hybrid nanomaterials, such as AuNPs tagged with π-conjugated molecules with aggregation-induced emission (AIE) property, are promising candidates to develop fluorescent materials for cellular imaging. The combination of NHC-stabilized AuNPs with AIE to form stable, fluorescent hybrid AuNPs is of significant interest to open the door to develop new NHC-based nanomaterials. Herein, we report the synthesis and characterization of water-soluble fluorescent NHC-decorated AuNPs for potential applications in nanomedicine. Their stability in biologically relevant conditions is investigated.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0260
Efficient protocol for the preparation of α-heteroaryl
acetaldehydes
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  Authors: Cohan Huxley, Callum Lucas, Juan Manuel Mesa Bruno, Matthew J. Anketell, Emma K. Davison, Garrett Muir, Matthew B. Nodwell, Michael Meanwell, Steven M. Silverman, Robert Britton, Louis-Charles Campeau
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  α-heteroaryl acetaldehydes have become important building blocks in the synthesis of synthetic nucleosides. Novel organocatalytic cascades have enabled the rapid generation of nucleosides, which are valuable building blocks in the development of antisense oligonucleotides or as stand-alone antiviral and anticancer therapies, obviating the need for laborious synthetic routes relying on chiral pool starting materials and inefficient synthetic routes. This manuscript describes a robust and scalable protocol to α-heteroaryl acetaldehydes from readily available building blocks.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-05-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0275
A fluorescence sensor based on quantum dots for the detection of mercury
ions
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  Authors: Yang Qin, YunHan Yang, Yi-Ping Ho, Ling Zhang
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Mercury(II) ion (Hg2+) is one of the most widespread pollutants that poses a serious threat to public health and the environment. Research efforts on selective and sensitive detection of Hg2+ have therefore drawn considerable attention in recent years. Herein, we report a facile approach to detect Hg2+ based on quantum dot (QD)-based nanosensor. The two single-stranded DNA (ssDNA) used in this work are modified with biotin (ssDNA–biotin) and fluorescence black hole quencher BHQ2 (ssDNA–BHQ2). These two strands are complementary but with TTT-recognized base sequences for the Hg2+ to form a T–Hg2+–T complex. The biotin-modified ssDNA (ssDNA–biotin) is first bound to the streptavidin-modified QDs, forming a QDs/ssDNA–biotin assembly, which may be further hybridized with the ssDNA–BHQ2, producing a complex of QDs/ssDNA–biotin/ssDNA–BHQ2. The BHQ2 serves as an effective quencher of QDs with the QDs and BHQ2 in a proximity within the QDs/ssDNA–biotin/ssDNA–BHQ2 complex. The decrease of fluorescence intensity therefore serves as an indication of the presence of Hg2+. The fluorescence reduction is observed linearly correlated with the concentration of Hg2+ in the range of 1.0–20.0 nmol/L, with a detection limit at 0.87 nmol/L. The presented QD-based method is expected to provide a simple, rapid, and sensitive method for the detection of Hg2+ in environmental water samples.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-25T07:00:00Z
  DOI: 10.1139/cjc-2022-0145
New bis(thieno[2,3-b]pyridine) hybrids linked to arene units as potential
bacterial biofilm and MRSA inhibitors
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  Authors: Sherif M.H. Sanad, Ahmed E.M. Mekky
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Using sonication and mediated by piperazine, new arene-linked bis(thieno[2,3-b]pyridine) hybrids were efficiently prepared in this study. The target hybrids were prepared by reacting bis(α-haloketone) with two equivalents of the appropriate pyridine-2(1H)-thiones in the presence of 1.4 equivalents of piperazine. The reaction mixture was subjected to sonication at 60 °C for 30–40 min to produce the desired products in 88%–95% yields. When tested against six different ATCC bacterial strains, the new products demonstrated a wide range of antibacterial activity. The 4-(4-methoxyphenyl)-linked hybrids 1i and 1j, attached to 6-(4-methoxyphenyl) and 6-(p-tolyl) units, respectively, had the best efficacy against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa strains. Both hybrids showed more effective potency than the reference ciprofloxacin with MIC and MBC values in the ranges from 2.0 to 2.1, and 4.1 to 4.2 µM, respectively. Additionally, hybrids 1i and 1j demonstrated stronger efficacy than linezolid with MIC values ranging from 2.0 to 4.2 µM, and MBC values ranging from 8.2 to 8.5 µM, respectively, against the MRSA ATCC:33 591 and ATCC:43 300 strains. Furthermore, hybrids 1i and 1j showed inhibitory antibacterial biofilm activity comparable to the standard ciprofloxacin. They had IC50 values ranging from 3.8 to 4.6 µM against S. aureus, E. faecalis, E. coli, and P. aeruginosa strains. The cytotoxicity of hybrids 1i and 1j against the human breast epithelial cell line MCF-10A lends credence to both hybrids’ potential as safe antibacterial agents.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-20T07:00:00Z
  DOI: 10.1139/cjc-2022-0236
Synthesis of novel 2- and 8-substituted 4-amino-7-chloroquinolines and
their N-alkylated coupling products
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  Authors: Dion B. Nemez, Baldeep K. Sidhu, Kevin Carlin, Albert Friesen, David E. Herbert
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The synthesis of a series of 2- and 8-substituted 4-amino-7-chloroquinolines is presented. Starting from 4,7-dichloroquinolines, the chloro in the 4-position can be effectively substituted using amino alcohols to yield novel analogues of the antimalarial (hydroxy)chloroquine. Both short-chain (2-aminoethanol) and long-chain (5-[N-ethyl-N-(2-hydroxyethyl)amino]-2-aminopentane) coupling partners can be used. While ketone and nitro functionalities were found to be incompatible with the coupling conditions, electron-donating amino and dimethylamino substituents were tolerated. In addition to characterization in solution using multinuclear NMR spectroscopy and high-resolution mass spectrometry, single-crystal X-ray structures are presented of two 4,7-dichloroquinolines as well as three of the N-alkylated products including a unique species in which a pyrrole heterocycle formed at the 2-position of the quinoline subunit and a rare example of a 4-aza-1,10-phenanthroline.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-20T07:00:00Z
  DOI: 10.1139/cjc-2023-0005
Novel CoMnFeO4-MWCNT nanocomposite based on a green synthesized method for
supercapacitor applications
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  Authors: Aziz Babapoor, Behruz Mirzayi, Laleh Salehghadimi, Raha Hadi, Sana Farhoudian, Meysam Paar
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  A novel nanocomposite of CoMnFeO4-MWCNT has been synthesized via green and simple hydrothermal method and the structure characterization has been done through FT-IR, X-ray diffraction, scanning electron microscopy, EDX, and high-resolution transmission electron microscopy analysis in this research. Cyclic voltammetry and galvanostatic charge–discharge methods are picked as the strategies to compare their supercapacitor behavior. The specific capacitance of about 1310 F g−1 (at 1 A g−1) in 3 mol L−1 KOH has been recorded for CoMnFeO4-MWCNT nanocomposite when the working voltage is 1.2 V. Moreover, this nanocomposite retains 89% of its initial capacitance after 10 000 charge–discharge cycles. Also, some initial mechanistic studies are performed to achieve a deeper insight into the electrochemical behavior of the nanocomposite implying that the oxidation-reduction process of CoMnFeO4-MWCNT nanocomposite is generally quasi-reversible and diffusion-controlled. From the view of time, coat, and environment, the hydrothermal process is much more reliable and beneficial regarding higher performance.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-11T07:00:00Z
  DOI: 10.1139/cjc-2022-0117
Synthesis and structural studies of group 12 oxazoline-enolate
coordination complexes of
(Z)-1-R-2-(4′,4′-dimethyl-2′-oxazolin-2′-yl)-eth-1-en-1-ates; part
I: the zinc derivatives
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  Authors: Matthew C. Hill, Alan J. Lough, Robert A. Gossage
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The synthesis and characterisation (IR, NMR, HR-MS, and X-ray crystallography) of six oxazoline Zn complexes, containing enolate ligands derived from a series of (Z)-1-R-2-(4′,4′-dimethyl-2′-oxazolin-2′-yl)-eth-1-en-1-ols (R = C6H5, C6H4-p-NO2, C6H4-p-OCH3, CF3, CH3, or CMe3) is detailed. All derivatives are air-stable solids of formula Zn(L n )2 and are formed in the presence of the title ligands and NEt3. Reasonable yields (53%–82%) are obtained with the exception of R = CMe3 (9%); in this case, by-product formation and high solubility affected complex isolation. Crystallographic characterisation reveals that in all cases the ligands are bound in a κ2-N,O-bonding motif. Little structural diversity is noted within the series; these complexes are further placed into structural context with related Zn materials containing oxazoline, phenolate, and (or) Schiff base ligands.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-06T07:00:00Z
  DOI: 10.1139/cjc-2022-0307
Environment polarity effects on the microscopic nonlinear optical
properties of some asymmetrical azobenzene molecules
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  Authors: M. Khadem Sadigh, A.N. Shamkhali
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Solvent as a complex environment can surround solute molecules and modify their function. In this work, different solute–solvent interaction effects on the nonlinear optical behavior of some azo dyes were studied at the molecular level. In this case, spectroscopic technique and density functional theory were used. According to the results, molecular dipole transition, changes between ground and excited state dipole moments, substituent, and environment polarity play considerable effects on the molecular nonlinear optical responses. In addition to solvent effects on the molecular first- and second-order hyperpolarizability, the two-photon absorption cross-section is also modified due to solvent-induced interactions. Moreover, the determination of the contribution of dominant solvent effects on the molecular nonlinear optical behavior can facilitate the studies on the application of optical samples in designing various optical systems.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-06T07:00:00Z
  DOI: 10.1139/cjc-2022-0083
The viscosity reducers exhibit dispersing ability for resin in heavy oil
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  Authors: Langman Xing, Hongping Quan, Jinyang Zhao, Xiaomei Huang
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The viscosity of the heavy oil was closely correlated with its own resin content by comparing three types of crude oil. In this paper, two novel viscosity reducers with characteristic groups in molecular structures were synthesized for Xinjiang heavy oil, namely viscosity reducer 1 (VR-1) and viscosity reducer 2 (VR-2), both of them showed the better viscosity reduction effect on Xinjiang heavy oil and VR-2 was better than VR-1. The measurement results of ultraviolet-visible spectrophotometer and scanning electron microscope showed that the VR-2 had better separation effect for resin than the VR-1. By analyzing the infrared spectrum results of resin molecule, it could be seen that the resin molecule contained more heteroatoms, which could more easily form the stronger hydrogen bonding with VR-2 with more polar groups to result the better resin dispersion effect. Hence, the phenomenon that VR-1 was not as good as VR-2 in improving fluidity of Xinjiang heavy oil was explained.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-06T07:00:00Z
  DOI: 10.1139/cjc-2022-0165
When is a pyridine not a pyridine' Benzannulated N-heterocyclic ligands in
molecular materials chemistry
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  Authors: David E. Herbert
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The C═N bond is a critical structural piece of many N-donor ligand scaffolds and is central to the properties and reactivity of important coordination complexes. For example, C═N units play a key role in the “redox non-innocence” of α-diimine complexes and in making charge-transfer excited-state character available to complexes of N-heterocyclic ligands such as bipyridine. In N-heterocycles like pyridine, benzannulation can be used to extend the conjugated C═N-containing π-system to quinoline (2,3-benzopyridine) to acridine (2,3-benzoquinoline). This stabilizes the lowest unoccupied molecular orbital of the molecule and boosts its electron-accepting properties, but the position of the benzannulation matters. For example, phenanthridine (3,4-benzoquinoline), an asymmetric isomer of acridine, bears a similarly electronically accessible extended π-system but with a more chemically isolated “imine-like” C═N moiety. This award paper presents an overview of our work investigating the impact of such site-selective benzannulation on the chemistry and properties of phenanthridine as a molecule and ligand.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0314
Benchtop 19F nuclear magnetic resonance spectroscopy enabled kinetic
studies and optimization of the synthesis of carmofur
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  Authors: Xina Wang, Julia Vu, Charissa Luk, Edward Njoo
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Carmofur, a 5-fluorouracil (5-FU) derivative, was initially developed as an antineoplastic agent to treat colorectal cancer. Through drug repurposing efforts, it has been identified as a potent covalent inhibitor of the main protease of SARS-CoV-2 (Mpro), making it a promising therapeutic agent against COVID-19. However, previous synthetic procedures suffer from low yields or long reaction times. In this study, benchtop 19F nuclear magnetic resonance (NMR) spectroscopy enables the real-time quantitative monitoring and characterization of the synthesis of carmofur by providing kinetic insight. Furthermore, its proton lock capabilities no longer require the use of deuterated solvents and have enabled convenient and rapidly scalable synthesis of our compound. Here, we present the application of benchtop 19F NMR as an efficient method for optimizing the synthesis of carmofur and its future application in the synthesis of related 5-FU analogs.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0266
Gathering validity evidence in the development of a new version of the
Attitude toward the Subject of Chemistry Inventory (ASCI-UE)
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  Authors: Guizella A. Rocabado, Lilian H. Montes, Roberto Ferreira, Cristina Rodríguez, Jennifer E. Lewis
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Organic chemistry is one of the most feared and failed courses due to its complex and fast-paced nature. Investigating affective metrics that relate to achievement in these courses can be worthwhile, particularly when these metrics show predictive relationships to achievement. Attitude toward chemistry has been investigated utilizing a variety of instruments. We present herein an instrument related to the well-established Attitude toward the Subject of Chemistry Inventory (ASCIv2). This new instrument was developed utilizing The Standards of Psychological and Educational Measurement, which describe five aspects of validity evidence that should be gathered when using instruments in research. Content validity was gathered through consultation with experts. Response process validity was gathered through student interviews. Internal structural validity was collected through confirmatory factor analysis. Relations to other variables were investigated through correlation analysis and structural equation modeling. Consequential validity was studied through measurement invariance testing before comparing scores for subgroups (high- and low-achieving students). Additionally, reliability evidence was tested with Omega coefficients for each of the factors. We showed that all tests and analyses were done with high rigor, and that this new instrument, ASCI-UE, measuring utility and emotional satisfaction, can provide interesting results and implications for research and practice.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0162
Investigating the Rydberg states and photodissociation dynamics of Kr2
using velocity map imaging
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  Authors: Cailum M.K. Stienstra, Neville J.A. Coughlan, Alexander Haack, Patrick J.J. Carr, Jeff Crouse, Joshua Featherstone, W. Scott Hopkins
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Although the krypton dimer, Kr2, is a prototypical weakly bound van der Waals complex in its ground electronic state, the excited states of Kr2 exhibit many and various interactions. Resonance-enhanced multiphoton ionization and velocity map imaging provide an avenue to explore the electronic structure and photofragmentation dynamics of Kr2 in the vacuum ultraviolet region. By monitoring photofragmentation product channels and recoil anisotropy distributions, one can gain insights into excited state symmetries and lifetimes, which can aid in interpreting spectroscopy. Here, we study the spectroscopy and photodissociation dynamics of Kr2 in the 91 000–94 500 cm−1 region. We record and assign photofragment product channels for 32 vibronic bands corresponding to seven electronic transitions. We also identify two previously unobserved vibronic band systems, which we assign as the Kr2 5p [5/2]3 [math] and 5p [3/2]2 [math] transitions. Velocity map images show photofragments arising from predissociation of the neutral Rydberg states and from dissociative photoionization at the n > 2 photon level. We also observe variation in branching ratios between the predissociative and dissociative photoionization channels depending on the lifetime of the intermediate; longer lived states favour higher dissociative photoionization yields and exhibit β6 anisotropy parameters for predissociation product channels, indicating “rotational smearing” of the product angular distributions.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0283
Visible-light photoredox-catalyzed coupling of alkylsulfones with
α-(trifluoromethyl)styrenes
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  Authors: Yasuyo Tahara, Koushik Ghosh, Masakazu Nambo
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The synthesis of gem-difluoroalkenes by photocatalytic desulfonylative coupling of alkylsulfones with α-(trifluoromethyl)styrenes is described. Photoredox Ir complex was found to be an effective catalyst for this transformation through single electron reduction of alkyl 1-phenyltetrazolyl sulfones, providing structurally diverse gem-difluoroalkene products in good yields. The resulting alkenes could be further converted into fluorinated derivatives, highlighting the potential utility of this method in the synthesis of organofluorine compounds.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0271
Revisiting the coupling reaction between 4-aminoantipyrine and phenols: a
potential one-pot reaction pathway to 4,11- and 5,12-naphthoxazepine
isomers
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  Authors: Ochan Otim
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  A while ago, this journal (Canadian Journal of Chemistry) published a set of seminal studies that revealed the underlying mechanism supporting the widely used 4-aminoantipyrine (4-AAP)-based analytical technique for detecting phenols at low levels in domestic water supplies. The current paper revisits these studies, but with a primary focus on an aspect of the mechanism that synthesizes a 6- and a 7-membered heterocyclic ring containing both N and O in a single step. Here we report a rather unusual outcome of this aspect in which, while the same naphthoquinonimide product is produced in the oxidative coupling of 4-AAP to 1-naphthol in aqueous solution and in the condensation of 4-AAP with 1,4-naphthoquinone in chloroform, a similar pair of reactions with 2-naphthol and 1,2-naphthoquinone produces two oxazepine isomers instead. In one isomer, the 4-AAP/naphthol C–N and C–O linkages are at positions 1 and 2 of the naphthyl ring, respectively; in the other isomer, these linkages are at positions 2 and 1, respectively. This unexpected difference in a one-pot reaction at ambient temperature is potentially the flexibility needed to synthesize families of pharmaceutically relevant oxazepines. Spectroscopic features useful for identifying 12 heterocyclic compounds synthesized here, nine of which are new, are also provided.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0239
Synthesis, anticancer evaluation, and molecular docking study of some
arylidenehydrazono analogues
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  Authors: Mohamed H.A. Soliman, Nashwa M. Mahmoud, Aml B. Mohamed, Howayda E. Khaled
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  A series of 2-(arylidenehydrazono)-5-(2-oxo-2-arylethyl)thiazolidin-4-one derivatives was synthesized, characterized by spectral analyses and evaluated for their in vitro antitumor activity. The IC50 determination of compounds was investigated on the human breast cancer cell line MCF-7. Among the series, compounds 3, 6, 10, 16, 17, and 24 showed remarkable anticancer activity with mean IC50 values 2.34, 0.73, 2.69, 3.40, 1.18, and 1.76 µg/mL, respectively, against MCF-7 cancer cells. Compound 16 enhanced the concentration of caspase-9, inhibited the concentration of Ki67 and showed a profound reduction in the amount of MMP9 secreted into the medium of MCF-7-treated cells. Furthermore, compound 16 revealed anti-angiogenic activity through downregulation of the concentration of VEGF in the medium of MCF-7-treated cells. Compound 16 exerted cytotoxic effects on MCF-7 tumor cells via antiproliferative, apoptotic, anti-angiogenic, and antimetastatic activities. Molecular docking methodology was performed for the most effective anticancer compounds to rationalize the possible interactions with active site of VEGFR-2 enzyme.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-04-05T07:00:00Z
  DOI: 10.1139/cjc-2022-0276
Grid-based state space exploration for molecular binding
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  Authors: Hana Zupan, Frederick Heinz, Bettina G. Keller
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Binding processes are difficult to sample with molecular dynamics (MD) simulations. In particular, the state space exploration is often incomplete. Evaluating the molecular interaction energy on a grid circumvents this problem but is heavily limited by state space dimensionality. Here, we make the first steps towards a low-dimensional grid-based model of molecular binding. We discretize the state space of relative positions and orientations of the two molecules under the rigid body assumption. The corresponding program is published as the Python package molgri. For the rotational component of the grids, we test algorithms based on Euler angles, polyhedra and quaternions, of which the polyhedra-based are the most uniform. The program outputs a sequence of molecular structures that can be easily processed by standard MD programs to calculate grid point energies. We demonstrate the grid-based approach on two molecular systems: a water dimer and a coiled-coil protein interacting with a chloride anion. For the second system we relax the rigid-body assumption and improve the accuracy of the grid point energies by an energy minimization. In both cases, oriented bonding patterns and energies confirm expectations from chemical intuition and MD simulations. We also demonstrate how analysis of energy contributions on a grid can be performed and demonstrate that electrostatically driven association is sufficiently resolved by point-energy calculations. Overall, grid-based models of molecular binding are potentially a powerful complement to molecular sampling approaches, and we see the potential to expand the method to quantum chemistry and flexible docking applications.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-03-27T07:00:00Z
  DOI: 10.1139/cjc-2022-0282
Time-dependent multiconfiguration self-consistent-field and time-dependent
optimized coupled-cluster methods for intense laser-driven multielectron
dynamics
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  Authors: Takeshi Sato, Himadri Pathak, Yuki Orimo, Kenichi L. Ishikawa
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  We reviewed the time-dependent multiconfiguration self-consistent-field (TD-MCSCF) method and the time-dependent optimized coupled-cluster (TD-OCC) method for first-principles simulations of high-field phenomena such as tunneling ionization and high-order harmonic generation in atoms and molecules irradiated by a strong laser field. These methods provide a flexible and systematically improvable description of the multielectron dynamics by expressing the all-electron wavefunction by configuration interaction expansion or coupled-cluster expansion, using time-dependent one-electron orbital functions. The time-dependent variational principle plays a key role in deriving these methods while satisfying gauge invariance and Ehrenfest theorem. The real-time/real-space implementation with an absorbing boundary condition enables the simulation of high-field processes involving multiple excitation and ionization. We present a detailed, comprehensive discussion of such features of the TD-MCSCF and TD-OCC methods.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-03-14T07:00:00Z
  DOI: 10.1139/cjc-2022-0297
Adsorption of tetracycline antibiotics to gold nanoparticles and
feasibility of aptamer-based label-free colorimetric detection
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  Authors: Yuheng Song, Derek H.G. von Eppinghoven, Yang Zhou, Hanxiao Zhang, Juewen Liu
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Tetracyclines are a group of very important antibiotics that are still in use. To extract, detect, and remove tetracyclines from the environment, various nanomaterials have been employed. Although gold nanoparticles (AuNPs) are a commonly cited material for these purposes, a fundamental understanding of these tetracycline-AuNP systems is still limited. In this work, the adsorption of tetracycline, oxytetracycline, and doxycycline to AuNPs was studied. The effect on the colloidal stability of AuNPs, adsorption kinetics, and the resulting adsorption isotherms was measured. While millimolar concentrations of the tetracyclines can cause aggregation of AuNPs, saturated monolayer adsorption was achieved with low micromolar concentrations of the tetracyclines. Adsorption was instantaneous, and adsorption to AuNPs enhanced their intrinsic fluorescence instead of quenching. With the assumption that aptamer/target complexes cannot be easily adsorbed by AuNPs compared to free aptamers, a label-free colorimetric detection method was tested. While the label-free sensor showed target-dependent aggregation of AuNPs, a nonbinding mutant aptamer showed the same trend, suggesting that the color change did not reflect aptamer adsorption but other events such as target adsorption. This study indicates the importance of the fundamental understanding of target/AuNP interactions to correctly design aptamer and AuNP-based label-free biosensors.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-03-10T08:00:00Z
  DOI: 10.1139/cjc-2022-0253
Scan rate and concentration dependence of the voltammograms of substituted
phenols on electrodes with different size, diffusion coefficients of
phenols in different solvents
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  Authors: László Kiss, Sándor Kunsági-Máté
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  In this work, the effects of the scan rate and the concentration of the substituted phenols on the peak currents or current plateaus have been investigated. Voltammetric curves recorded by a platinum microelectrode varied significantly under different experimental conditions in cases of 4-chlorophenol, 4-tert-butylphenol, and 4-nitrophenol. In the case of 4-methoxyphenol and 4-tert-butylphenol, when the experiments were performed in the lower concentration range in acetonitrile, the plateau current and peak current showed linear dependence on phenol concentration. Therefore, these ranges offer opportunity for further characterization. The electrode reaction of 4-methoxyphenol was found to be a diffusion-controlled process in the solvents applied (water, acetonitrile, dimethyl sulfoxide, dimethyl formamide, nitrobenzene, acetone, dichloromethane, methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol). Diffusion coefficients of 4-methoxyphenol were determined with a microelectrode using the steady-state voltammograms. Diffusion coefficients of other phenols were measured only in acetonitrile with a macroelectrode. In agreement with known theories, the diffusion coefficients showed inversely proportional relationships with the solvent viscosities. Special care was needed in 1-pentanol solvent since the increasing anodic peaks appeared after the first scan and overlaid with the sigmoidal-shaped regular microelectrode voltammograms. This observation is probably due to formation of adhering residual electroactive products.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-02-24T08:00:00Z
  DOI: 10.1139/cjc-2022-0096
Dicarbon defect in hexagonal boron nitride monolayer—a theoretical
study
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  Authors: Tatiana Korona, Joanna Jankowska, Emran Masoumifeshani
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  A comprehensive theoretical study of the lowest electronic vertical excitations of the CBCN defect in the monolayer of hexagonal boron nitride has been performed. Both the periodic boundary conditions approach and the finite-cluster simulation of the defect have been utilized at the density-functional theory (DFT) level. Clusters of increasing sizes have been used in order to estimate artefacts resulting from edge effects. The stability of the results with respect to several density functionals and various basis sets has been also examined. High-level ab initio calculations with methods like equation-of-motion coupled cluster method with single and double excitations (EOM-CCSD), algebraic-diagrammatic construction to the second order (ADC(2)), and time-dependent approximate coupled cluster theory to the second order (TD-CC2) were performed for the smallest clusters. It turns out that TD-DFT with the CAM-B3LYP functional gives similar lowest excitation energies as EOM-CCSD, ADC(2), and TD-CC2. The lowest excitation energies resulting from the periodic-boundary calculation utilizing the Bethe–Salpeter equation are in agreement with the results for finite clusters. The analysis of important configurations and transition densities shows that for all studied methods, the lowest excited state is localized on two carbon atoms and their closest neighbours and has a large dipole transition moment. The optimized geometries for the lowest two excited states indicate that in both cases, the carbon–carbon bond becomes a single bond, while for the second excited state, additionally one from boron–nitrogen bonds loses its partially double character. The calculation of the excitation energies at the respective optimal geometry reveals that these two energies become about 0.5 eV lower than vertical excitations from the ground-state geometry.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-02-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0291
Convenient access to β-substituted cysteines and β- and
γ-mercapto prolines
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  Authors: Jacob C. Hansen, Marco Rabuffetti, Lennart Bunch
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Herein we describe a convenient method for the synthesis of the β-substituted Cys analogs 1a, b and trans-β-mercapto proline 1c, from their corresponding α,β-unsaturated-α-amino esters using p-methoxybenzyl mercaptan as the sulfur source. The intermediate β-thioethers are stable toward chromatographic purification, and after global deprotection the β-mercapto amino acids 1a–c are obtained in good to high yields (64%–99%).
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-02-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0161
Predicting reaction barriers in solid-state systems under stress via
second-order energy expansion
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  Authors: Laura Laverdure, Nicholas Mosey
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Solid-state transformations are important in many areas of science and technology. Herein, a model for predicting the relative energies of stationary points along the reaction pathways for stress-induced solid-state transformations is assessed and applied. The model is based on a second-order expansion of the energy of the system with respect to changes in the unit cell, and requires a small number of parameters that can be obtained through quantum chemical calculations. Comparison of the model with the results of quantum chemical calculations indicates that the model accurately reproduces changes in energy occurring during stress-induced transformations over a reasonable range of stresses. A procedure for applying the model to identify stress tensors that are most likely to promote a desired reaction is illustrated. The results also indicate that this procedure provides insight into the connection between the form of a stress tensor and the changes in energy occurring during a stress-induced solid-state transformation.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-02-14T08:00:00Z
  DOI: 10.1139/cjc-2022-0278
Nickel-catalyzed N-arylation of optically pure amino acid esters with
activated (hetero)aryl electrophiles
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  Authors: Travis Lundrigan, Joseph P. Tassone, Mark Stradiotto
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  An efficient method for the C–N cross-coupling of (hetero)aryl (pseudo)halides with optically pure α-amino acid esters employing a commercially available nickel catalyst and weak inorganic base was developed. This is the first example of Ni-catalyzed N-arylation of amino acid esters without the use of electrochemistry, which was shown to effectively couple a variety of amino acid tert-butyl esters with (hetero)aryl chlorides, bromides, and tosylates in high yields and excellent enantioretention. Base-mediated racemization was revealed during control experiments, but increasing the steric bulk of the amino acid ester group limited the amount of racemization of the product.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-02-02T08:00:00Z
  DOI: 10.1139/cjc-2022-0290
Is explicitly correlated double-hybrid density functional theory
advantageous for vibrational frequencies'
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  Authors: Nisha Mehta, Golokesh Santra, Jan M.L. Martin
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  We have investigated the effect of F12 geminals on the basis set convergence of harmonic frequencies calculated using two representative double-hybrid density functionals, namely, B2GP-PLYP and revDSD-PBEP86-D4. Like previously found for energetics (Mehta N.; Martin J. M. L. J. Chem. Theory Comput. 2022, 18, 5978), one sees an acceleration by two zeta steps, such that even the cc-pVDZ-F12 basis set is quite close to the complete basis set (CBS) limit. However, the basis set convergence problem is not as acute as for energetics, and compared with experimental harmonic frequencies, conventional orbital calculations with augmented triple zeta quality basis set are acceptably close to the CBS limit, and can be carried out using analytical second derivatives. An efficient implementation of double-hybrid F12 analytical derivatives would make the F12 approach attractive in the sense that even an spd orbital basis set would be adequate. For the accurate revDSD-PBEP86-D4 functional, the role of differing local correlation terms (Perdew–Zunger 1981 versus VWN5) in different electronic structure programs has been investigated, while optimal double-hybrid parameters and performance statistics for energetics as well as frequencies differ slightly between the two implementations; these differences are insignificant for practical purposes.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-01-19T08:00:00Z
  DOI: 10.1139/cjc-2022-0277
Thermal and electrical transport conductivities of novel ordered double
two-dimensional MXenes via density functional theory
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  Authors: E. Omugbe, O.E. Osafile, N.O. Nenuwe, E.A. Enaibe, E.E. Elemike
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  In this paper, we examined the effects of transition metal replacement and ordering in 2D M3C2O2 MXene on the electronic structure and thermal and electrical conductivities using the density functional theory and also Boltzmann’s transport theory within the constant relaxation time approximation. We derived the following oxygen-functionalized ordered double-metal MXenes Ti2YC2O2, Y2TiC2O2, Sc2YC2O2, and Y2ScC2O2 through the surface and sub-layer tuning. The results revealed that the ordered MXenes give rise to different electronic structure and transport properties. The electronic thermal conductivities obtained in terms of the relaxation time increase with increase in absolute temperature, while the electrical conductivities decrease with increase in temperature. The respective transport properties of Y2TiC2O2 and Sc2YC2O2 were found to be enhanced due to the increased squared band velocity, density of state, and low Seebeck coefficient compared to Ti2YC2O2 and Y2ScC2O2 MXenes. Generally, the MXene materials investigated in this work were found to possess metallic properties with the existence of energy overlap around the Fermi level. The computed formation energies support chemical stability in all the materials.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-01-19T08:00:00Z
  DOI: 10.1139/cjc-2022-0070
Ultrasensitive electrochemical phosphate detection by
pyridine–zinc(II) complex
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  Authors: Kailey Browne, Yu Pei, Ishwar Singh, Sarah Jane Payne, Zhe She
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Phosphorous is an important environmental health parameter as the availability of phosphorus within water systems plays an essential role in the prevalence of harmful algal blooms (cyanobacteria blooms). Currently, phosphates are detected using sensitive chromatographic and colorimetric techniques; however, major disadvantages stem from the lack of anion selectivity in samples with complex matrices, as well as the high cost of analysis. Electrochemical techniques utilizing self-assembled monolayers can provide a cheaper yet sensitive method of detection. This work explores the modification of a gold working electrode using pyridine–zinc(II) complexes. The implementation of self-assembled monolayers allows for an ultrasensitive and selective method of indirect detection of the H2PO4 − species, ranging in concentrations between 0.0 and 1.2 fmol/L phosphate. Electrochemical techniques such as cyclic voltammetry and square-wave voltammetry were explored for their phosphate-detection abilities, with detection limits of 4.0 × 10−16 and 9.0 × 10−17 mol/L H2PO4 −, respectively. X-ray photoelectron spectroscopy measurements were also taken to confirm the modification of the electrode. The selectivity of this sensor towards phosphate anions was successfully explored for this sensor in the presence of potential interfering agents (sulfate, chlorine, carbonate, fluoride, nitrite, and hypochlorite ions), and applicability of sensor was also explored through the detection of phosphate in a tap and lake water sample.
  Citation: Canadian Journal of Chemistry
  PubDate: 2023-01-13T08:00:00Z
  DOI: 10.1139/cjc-2022-0212
Intersystem crossing and intramolecular triplet excitation energy transfer
in spiro[9,10-dihydro-9-oxoanthracene-10,2′-5′,6′-benzindan]
investigated by DFT/MRCI methods
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  Authors: Simon Metz, Tobias Böhmer, Ben Raunitschke, Christel M. Marian
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Recent experimental studies of a spiro-linked anthracenone (A)–naphthalene (N) compound (AN) in butyronitrile (BuCN) solution (Dobkowski et al., J. Phys. Chem. A 2019, 123, 6978) proposed an excited-state energy dissipation pathway [1ππ* (N) + 1ππ*(A)]↝1nπ* (A)↝3nπ* (A)↝3ππ*(N). However, a detailed theoretical study employing combined density functional theory and multireference configuration interaction methods, performed in the present work, suggests that the photoexcitation decay follows a different pathway. In BuCN solution, the intersystem crossing (ISC) follows the well-established El-Sayed rule and involves the 3ππ*(A) state which is found to be the lowest excited triplet state localized on the anthracenone moiety. Because the Dexter triplet excitation energy transfer (TEET) to the first excited triplet state of the naphthalene subunit is forbidden in C2v symmetry, it is mandatory to go beyond the Condon approximation in modeling this process. Nonadiabatic coupling matrix elements were computed to obtain a TEET rate different from zero. Our calculations yield time constants of 5 ps for the 1nπ* (A)↝3ππ* (A) ISC and of 3 ps for the subsequent 3ππ* (A)↝3ππ* (N) TEET in BuCN whereas the energy dissipation involving the 3nπ*(A) state as an intermediate occurs on a much longer time scale.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-22T08:00:00Z
  DOI: 10.1139/cjc-2022-0259
Polypyridine-based architectures for smart electrochromic and energy
storage materials
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  Authors: Nadia O. Laschuk, Iraklii I. Ebralidze, Olena V. Zenkina
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The emerging role of metal–organic coordination compounds in the development of electrochromic materials (ECMs) fueled a growing interest in both the development of the new systems and their effective integration into functional devices. Coordination complexes of late transition metals with polypyridine ligands, like 2′-bipyridine (bpy) and 2,2′:6′,2″-terpyridine (tpy) often feature bright colours as a result of strong metal-to-ligand charge transfer. These colours could be reversibly bleached by oxidation of the metal centre and restored upon the metal centre reduction. The colour and its intensity can be controlled in different ways: by changing the nature of the metal centre(s) and by structural modification of ligand(s); by the construction of various metal–organic motifs and embedding them into devices, as well as by controlled layer-by-layer growth of the coordination assemblies on the surface of interest. The versatility of the available molecular building blocks allows for the systematic programming of the desired properties of the metal–organic units that could be effectively translated into the devices. This makes polypyridine metal complexes advantageous candidates for the design of effective ECMs. Here, we review the evolution of ECMs and devices based on molecularly defined bpy and tpy coordination adducts of late transition metals integrated into functional electrochromic devices over the past decade.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-22T08:00:00Z
  DOI: 10.1139/cjc-2022-0268
Enhancing catalytic activity of V2O5/TiO2 in H2S selective oxidation by
modulating oxygen adsorption conditions
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  Authors: Hyun Soo Lee, Jae Hwan Yang
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  This paper aimed to reveal the effects of chemisorbed oxygen species on selective catalytic oxidation applied for H2S removal. A sequence of thermal treatments were conducted on V2O5/TiO2 samples to prepare catalysts that possess different distributions of oxygen species. Characterization by X-ray photoelectron spectroscopy enabled a distinction among three different chemisorbed oxygen species: O–, O2 2–, and O2–. In addition, the dominance of the O– species, which is a very reactive oxygen species for catalytic oxidation reactions, was observed when the catalyst was exposed to 5% O2/N2 gas at the low temperature of 30 °C. It was also found that the N400A30 with the highest ratio of O– species was superior to others at converting H2S into elemental sulfur over the whole range of temperatures: the best S yield of N400A30 was 85% at 130 °C. These results are promising, as thermal treatments for oxygen adsorption were adopted for the first time to improve the catalytic activity of H2S removal by modulating the proportion of highly reactive O– species.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-19T08:00:00Z
  DOI: 10.1139/cjc-2022-0167
Weak and strong π interactions between two monomers—assessed with local
vibrational mode theory
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  Authors: Wenli Zou, Marek Freindorf, Vytor Oliveira, Yunwen Tao, Elfi Kraka
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  We introduce in this work a unique parameter for the quantitative assessment of the intrinsic strength of the π interaction between two monomers forming a complex. The new parameter is a local intermonomer stretching force constant, based on the local mode theory, originally developed by Konkoli and Cremer, and derived from the set of nine possible intermonomer normal vibrational modes. The new local force constant was applied to a diverse set of more than 70 molecular complexes, which was divided into four groups. Group 1 includes atoms, ions, and small molecules interacting with benzene and substituted benzenes. Group 2 includes transition metal hydrides and oxides interacting with benzene while Group 3 involves ferrocenes, chromocenes, and titanium sandwich compounds. Group 4 presents an extension to oxygen π–hole interactions in comparison with in-plane hydrogen bonding. We found that the strength of the π interactions in these diverse molecular complexes can vary from weak interactions with predominantly electrostatic character, found, e.g., for argon–benzene complexes, to strong interactions with a substantial covalent nature, found, e.g., for ferrocenes; all being seamlessly described and compared with the new intermonomer local mode force constant, which also outperforms other descriptors such as an averaged force constant or a force constant guided by the electron density bond paths. We hope that our findings will inspire the community to apply the new parameter also to other intermonomer π interactions, enriching in this way the broad field of organometallic chemistry with a new efficient assessment tool.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-16T08:00:00Z
  DOI: 10.1139/cjc-2022-0254
Synthesis and characterization of phosphorus-containing polymers for the
generation of polymer-derived ceramics
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  Authors: Kelly C. Duggan, Ian C. Watson, Paul J. Ragogna
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Phosphorus-containing polymer networks as precursors to polymer-derived ceramics were prepared using a combination of three monomers (1,3,5-triallyl-1,3,5-triazine-2,4,6-trione or 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, tetraethylene glycol diallyl ether, and isobutyl phosphine). By varying the stoichiometry of these components, it was observed that key properties such as thermal stability, swellability, and ceramic yield after pyrolysis can be modified at will. Optimal stoichiometries to achieve the highest ceramic yields upon pyrolysis, while maintaining swellability, were determined. Cobalt was introduced into the networks by reaction of the tertiary phosphine fragments in the material with CpCo(CO)2. After pyrolysis of the metalated polymers at 800 °C, the resulting ceramics were characterized using scanning electron microscopy-energy dispersive X-ray and X-ray photoelectron spectroscopy.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0258
C–H arylation enables synthesis of imidazole-4-carboxamide (ICA) based
fairy chemicals with plant growth-promoting activity
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  Authors: Ayaka Ueda, Kazuma Amaike, Yoko Shirotani, Robin Warstat, Hideto Ito, Jae-Hoon Choi, Hirokazu Kawagishi, Kenichiro Itami
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Imidazole-4-carboxamide (ICA), which is one of the groups of “fairy chemicals” (FCs) that cause the fairy ring phenomena, has plant growth inhibitory activity. FCs have the potential as candidates for a new family of plant hormones as they have been found endogenously in all plant species tested and show growth-regulating activities against the plants. While basic research on FCs is progressing, they are also expected to be applied not only to agrochemicals but also as pharmaceuticals. Derivatization of one of the FCs, 2-azahypoxanthine, and the structure–activity relationship (SAR) studies have clarified its activity as a plant growth promoter. Yet, ICA has not been derivatized at all and SAR regarding its activity remains unknown. In this study, we synthesized the derivatives of ICA by direct C–H arylation of ICA precursors and evaluated its activity in rice. The 12 total compounds including the arylated ICAs and their precursors were evaluated for root and shoot elongation in rice, resulting in the discovery that a number of compounds unexpectedly have an elongation activity in the root and shoot.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-14T08:00:00Z
  DOI: 10.1139/cjc-2022-0256
The phosphinoboration of thiosemicarbazones
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  Authors: Samuel R. Baird, Christopher M. Vogels, Stephen J. Geier, Lara K. Watanabe, Justin F. Binder, Charles L. B. Macdonald, Stephen A. Westcott
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  This study reports on the exploration of the phosphinoboration reaction with several thiosemicarbazones (R5R4NC(S)NR3N=CR1R2). Reactions between either Ph2PBpin (pin = 1,2-O2C2Me4) or Ph2PBcat (cat = 1,2-O2C6H4) with thiosemicarbazones containing a terminal primary or secondary amine afforded boron-containing heterocyclic 1,3,4-thiadiazoline products in excellent yield. The addition of Ph2PBpin to thiosemicarbazones containing an NMe2 group in the terminal position generated novel five-membered heterocycles in moderate yield, which included boron, sulfur, and nitrogen atoms. Heterocyclization of the thiosemicarbazones occurs preferentially in the presence of functional groups such as acetyl and pyridyl groups.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-12-09T08:00:00Z
  DOI: 10.1139/cjc-2022-0088
A molecular dynamics simulation investigation on the effects of Ser/Cys
exchange in the Ser–cisSer–Lys catalytic triad of malonamidase E2
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  Authors: Anupom Roy, James W. Gauld
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  The enzyme malonamidase E2 catalytically hydrolyzes malonamate (MLA) into malonate and ammonia. Its active site contains an uncommon Ser–cisSer–Lys catalytic triad that is critical to its functioning. Mutations of the residues in this triad can not only provide insight into its key features but also potentially identify how it may be influenced or adapted, i.e., decreased or increased. In this study, the effects of single and double Ser/Cys exchanges on the wild-type Ser155–cisSer131–Lys62 catalytic triad (i.e., Cys155–cisSer131–Lys62 (S155C), Ser155–cisCys131–Lys62 (S131C), and Cys155–cisCys131–Lys62 (S131C/S155C)) were examined. In particular, the dynamics and stability of the resulting substituted triads were examined along with their inter-triad residue hydrogen bonding interactions as well as those with other nearby residues and the MLA substrate. The present results suggest that some mutations are more impactful than others. Indeed, mutation of cisSer131 to cisCys131 disrupts the triad and causes inconsistent hydrogen bonding interactions among the triad residues (i.e., Ser155, Cys131, and Lys62). In contrast, in the double mutant Cys155–cisCys131–Lys62, the triad's residues appear to exhibit greater conformation stability with more consistent hydrogen bond interactions, though not necessarily as in the wild type.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-11-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0140
Highly sensitive and selective detection of selenate in water samples
using an enzymatic gold nanodendrite biosensor
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  Authors: Mozhgan Khorasani Motlagh, Meissam Noroozifar, Heinz-Bernhard Kraatz
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Gold (Au) and glassy carbon electrodes have been decorated with gold nanodendrites (NDs) using galvanic replacement reactions. Modification of the ND surfaces by lipoic acid N-hydroxysuccinimide ester allows to immobilise selenate reductase to the electrode surface, rendering it selective for the catalytic reduction of selenate ([math], Se(VI)) to selenite ([math], Se(IV)). Electrode modifications have been characterized by electrochemical impedance spectroscopy and cyclic voltammetry (CV). For selenate detection, CV and differential pulse voltammetry measurements have been carried out in 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid buffer with pH 6.0. Under optimum conditions, the linear range for Au electrodes decorated with AuNDs was 0.3–203 µg/L Se with a limit of detection of 0.01 µg/L Se, which is a 274-fold improvement over using non-nanostructured surfaces for selenate detection. Other anions such as [math], [math], [math], [math], [math], and [math] did not interfere with the detection of selenate. The electrochemical sensor was used for the detection of selenate in three different real samples with recovery between 98.5% and 102.0%.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-11-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0220
Effect of very high dose rates on the radiolysis of supercritical water at
400 °C and 25 MPa
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  Authors: Abida Sultana, Jintana Meesungnoen, Jean-Paul Jay-Gerin
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Monte Carlo multitrack chemistry simulations were used in combination with a cylindrical, “instantaneous pulse” irradiation model to study the effect of high dose rates on the early, transient yields (G values) of the “primary products” ([math], H•, H2, •OH, H2O2, H3O+, OH−, …) of the radiolysis of supercritical water (SCW) at 400 °C and 25 MPa pressure. Our simulation model consisted of randomly irradiating SCW with single pulses of N incident 300-MeV protons, which mimic the low linear energy transfer of 60Co γ/fast electron irradiations. The effect of dose rate was studied by varying N. Generally, high dose rates were found to favor radical–radical reactions, which increases the proportion of the molecular products at the expense of the radical products. However, as an exception, G(H•) increases with increasing dose rate in the track stage of radiolysis, predominantly due to the reaction of hydrated electrons with hydronium ions (H3O+). In addition, the generation of acidic spikes due to proton transfer reactions in the physicochemical stage was also examined. Interestingly, an early, transient, very acidic (pH ∼ 3.5) response was observed at high radiation dose rates across the entire irradiated volume. The present work raises the question of whether the potential oxidizing species •OH and H2O2 and these highly acidic pH spikes at high dose rates could promote a corrosive environment under proposed Generation IV SCW-cooled reactor or small modular reactor operating conditions that would lead to progressive degradation of materials.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-11-15T08:00:00Z
  DOI: 10.1139/cjc-2022-0210
Convenient preparation of copper(I) N-heterocyclic carbene complexes under
mild conditions
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  Authors: Meilin Q. Lim, Eric C. Keske
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  This work describes a new method for the preparation of copper N-heterocyclic carbene (NHC) complexes, which is conducted under air with mild conditions, using bench-stable precursors and a weak base (NEt3). Under optimized conditions, the complexes were prepared in short reaction times of 1 h, giving moderate to good yields after purification by column chromatography. Commonly utilized NHC–HCl salts were found to be applicable reacting with CuCl or CuI giving [(NHC)CuX]-type complexes (X = Cl, I). This study adds to the growing literature in the preparation of catalytically relevant transition metal NHC complexes under mild and operationally simple conditions.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-11-10T08:00:00Z
  DOI: 10.1139/cjc-2022-0229
Complexation-induced N‒P axial chirality in Sm(II) N-phosphine
oxide-substituted imidazolylidene and imidazolinylidene complexes
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  Authors: Yoichi Hoshimoto, Yasuhiro Yamauchi, Tomoya Terada, Sensuke Ogoshi
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Two types of Sm(II) complexes bearing either an N-phosphine oxide-substituted imidazolylidene (PoxIm) or the corresponding imidazolinylidene (SPoxIm) were successfully prepared and characterized using single-crystal X-ray diffraction analysis. The general formula of the structures of the complexes was found to be (anti-κ-O-(S)PoxIm) n SmX2(THF) m where X = I, n = 2, and m = 2 or X = pentamethylcyclopentadienyl, n = 1, and m = 0. The carbene carbon atoms remained intact in these complexes. In some cases, axial chirality was clearly induced around the N‒P bonds due to the restricted rotation of the N-phosphinoyl moieties, which arises from the formation of N-phosphinoyl oxygen‒Sm(II) bonds. This work highlights a rare example of complexation-induced N‒P axial chirality and new aspects regarding lanthanide complexes of multifunctional multipurpose carbenes.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-11-10T08:00:00Z
  DOI: 10.1139/cjc-2022-0249
Regioselectivity in Wacker oxidations of internal alkenes: antiperiplanar
effects'
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  Authors: W.O. Usama, D.J. Markewich, A.L.L. East
  Abstract: Canadian Journal of Chemistry, Ahead of Print.
  Computational chemistry, with considerable effort, was used to elucidate the reason for regioselectivity (12:1 distal:proximal product distribution) in a published Wacker oxidation of internal alkenes with a homoallylic lactam ring. Such a distribution is reproduced by a non-chelating reaction pathway; chelated intermediates are found to be too high in energy. Despite much speculation of chelation effects in the literature, this particular result is most probably an antiperiplanar field effect with no chelation. Partial charge data are provided to support the proposed antiperiplanar effect. The great care needed in modelling Wacker oxidations is emphasized, but optimism is offered that its various product mysteries can be elucidated on a case-by-case basis.
  Citation: Canadian Journal of Chemistry
  PubDate: 2022-09-01T07:00:00Z
  DOI: 10.1139/cjc-2022-0151