Volume 94, Issue 7

The important and perspective molecular building blocks composed of hexaphenylbenzenes (HPBs) or their oxidized derivatives, hexa-peri-hexabenzocoronenes (HBCs), and metalloporphyrins have recently received significant attention of the researchers. In this study, motivated by recent findings, we have addressed the modifications of structures and properties of HBC-porphyrin compounds by using instead of aromatic porphyrins antiaromatic 20π isophlorin derivatives of thiophene or selenophene. We have reported the first comparative computational investigation of the following systems: (i) HBC with one non-metallated aromatic porphyrin, P(N 4 H 2 ), unit, HBC-P(N 4 H 2 ), (ii) HBC with one S-core-modified antiaromatic porphyrin (S-isophlorin), PS 4 , unit, HBC-PS 4 , and (iii) HBC with one Se-core-modified antiaromatic porphyrin (Se-isophlorin), PSe 4 , unit, HBC-PSe 4 . The study has been done employing the B3LYP/6-31G* approach (in the gas phase and in the implicit solvents, benzene and dichloromethane), and comparison with the B3LYP/6-31G** and B3LYP/6-311G* approaches was performed, where relevant. The effects of the core-modified antiaromatic isophlorins on the structures, electronic, and other properties, potentially including reactivity, of the whole building block HBC-isophlorin have been shown to be quite pronounced and to be noticeably stronger than the effects of the original aromatic non-metallated porphyrin. Thus, we have demonstrated theoretically that the complete porphyrin core-modification with other elements, this time with S and Se leading to the formation of the antiaromatic isophlorins, should be considered as a promising way for modifying and tuning structures, electronic properties and reactivity of the hexabenzocoronene-porphyrin(s) building blocks.

A series of possible precursors for generating C 2 with the general formula Me 3 E–C 2 –I(Ph)FBF 3 [E = C ( 1 ), Si ( 2 ), and Ge ( 3 )] has been theoretically investigated using quantum chemical calculations. The equilibrium geometries of all species show a linear E–C 2 –I + backbone. The inspection of the electronic structure of the Me 3 E–C 2 bond by energy decomposition analysis coupled with the natural orbital for chemical valence (EDA-NOCV) method suggests a combination of electron sharing C–C σ -bond and v weak π -dative bond between Me 3 C and C 2 fragments in the doublet state for species 1 (E = C). For species 2 (Si) and 3 (Ge), the analysis reveals σ -dative Me 3 E–C 2 bonds (E = Si, Ge; Me 3 E←C 2 ) resulting from the interaction of singly charged (Me 3 E) + and (C 2 –IPh(BF 4 )) − fragments in their singlet states. The C 2 –I bond is diagnosed as an electron sharing σ -bond in all three species, 1 , 2 and 3 .

International frameworks have been put in place to foster chemical weapons nonproliferation and disarmament. These frameworks feature lists of chemicals that can be used as chemical weapons or precursors for their synthesis (CW-control lists). In these lists, chemicals of concern are described through chemical names and CAS Registry Numbers ® . Importantly, in some CW-control lists, some entries, rather than specifying individual chemicals, describe families of related chemicals. Working with CW-control lists poses challenges for frontline customs and export control officers implementing these frameworks. Entries that describe families of chemicals are not easy to interpret, especially for non-chemists. Moreover, synonyms and chemical variants complicate the issue of checking CW-control lists through names and registry numbers. To ameliorate these problems, we have developed a functioning prototype of a cheminformatics tool that automates the task of assessing whether a chemical is part of a CW-control list. The tool, dubbed the Nonproliferation Cheminformatics Compliance Tool (NCCT), is a database management system (based on ChemAxon’s Instant JChem) with an embedded database of chemical structures. The key feature of the database is that it contains not only the structures of the individually listed chemicals, but also the generic structures that describe the entries relative to families of chemicals (Markush structures).

Disinfecting activity test of four diphenyltin(IV) benzoate derivative compounds has been carried out. The four compounds investigated were diphenyltin (IV) di 4 aminobenzoate (DPDA) ( 2 ), diphenyltin (IV) di 4 chlorobenzoate (DPDC) ( 3 ), diphenyltin(IV) di-4-hydroxybenzoate (DPDH) ( 4 ), and diphenyltin(IV) di-4-nitrobenzoate (DPDN) ( 5 ), and they were prepared by reacting diphenyltin(IV) oxide (DPO) ( 1 ) with benzoic acid derivatives of 4-aminobenzoic acid (4-HABz), 4-chlorobenzoic acid (4-HCBz), 4-hydroxybenzoic acid (4-HHBz) and 4-nitrobenzoic acid (4-HNBz), respectively. The compounds were well characterized by 1 H, 13 C NMR, IR, UV spectroscopies, and their pieces were defined using microanalytical data. The disinfectant test was carried out on two bacteria, Gram-negative Salmonella sp . , and Gram-positive Staphylococus aureus. The result showed that all of the compounds were active as a disinfectant (disinfecting agent) with a minimum inhibitory concentration of 5 × 10 −4  M. Compound 5 was found to be most active compared to others which exhibited the ability to reduce the concentration of the S. aureus bacteria within 5 min.

Hepatitis C Virus ( HCV ) poses great threat worldwide, and is a major cause for liver cancer. HCV genome encodes polyprotein that is subsequently cleaved into independently functioning proteins, which spread viral infection in host. The Non-Structural 3 ( NS3 ) protease is responsible for cleaving the polyprotein, and may serve as a potential drug target. Since HCV has seven genotypes, the available drugs are predominantly designed for genotype 1 (GT1), and others prevalent in Europe. Consequently, these drugs lose efficacy when they are used for different genotypes. The current perspective study aims to find potential drug candidate against genotype 3 (GT3), prevalent in South Asia. The current study employed molecular docking technique and in silico ADME prediction tool to highlight potentially active compounds against HCV NS3 GT3. The study revealed Li_PIO_114 and Li_PIH_191 as potential lead compounds, as suggested by their docking score and ADME properties. These two compounds could be further optimized to improve their drug likeliness for curing HCV GT3.

Quantum chemical computations generate output files with data. The processing of these data generates results which are presented in a target document, such as a manuscript or supporting information (SI). Several tools and techniques can be employed to facilitate the transfer of data which, otherwise, can be time-consuming with a large number of files. However, depending on the user’s technical knowledge or expertise with the software, additional time has to be invested to set up the software or use the tools. In addition, to the best of the authors’ knowledge, the tools currently available do not provide an option to transfer the data from the output files directly to the target document without the use of custom scripts. The ExcelAutomat tool (Laloo et al. , J. Comput. Aided Mol. Des. 2017, 31, 667 and Laloo et al. , J. Comp. Chem. 2019, 40, 3) is spreadsheet-based and was developed in-house to facilitate the steps involved in the processing of computational files. The tool was adapted to facilitate the generation of SI in an update of ExcelAutomat 1.4. A graphical user interface was designed where the options for the generation of SI can be defined. ExcelAutomat 1.4 is compatible with Microsoft Excel and the open-source LibreOffice Calc. The extensible tool supports various software packages and parameters by interfacing with the cclib library and through built-in codes. The tool provides a method to transfer data from output files directly to a Microsoft Word or LibreOffice Writer document and can reduce the number of steps, tools or technical knowledge needed to generate SI, especially for users who are familiar with Microsoft Excel or LibreOffice Calc.

From the receptor-binding domain (RBD) of the SARS-CoV-2 virus, which causes coronavirus disease 2019 (COVID-19), a RBD-hFc fusion protein was obtained at the Center of Molecular Immunology (Havana, Cuba). This fusion protein was used in the construction of a diagnostic device for COVID-19 called Ultramicroenzyme-Linked Immunosorbent Assay (UMELISA)-SARS-CoV-2-IgG and it is currently been used in the studies of biological activity of the Cuban vaccine Abdala (CIGB-66). In this work, Circular Dichroism (CD) is used to characterize this protein. Using Far Ultraviolet Circular Dichroism (FAR-UV CD), it was determined that the protein has a secondary structure in the form of a sheet-β fundamentally. Using this technique, a thermodynamic study was carried out and it was determined that the melting temperature (Tm) of the protein is 71.5 °C. Information about the tertiary structure of the protein was obtained using Near Ultraviolet Circular Dichroism (NEAR-UV CD) and Molecular Fluorescence; they indicates that the protein has a three-dimensional folding associated with the aromatic amino acids in its structure, where tryptophan (Trp) is located inside the folded structure of the protein while tyrosine (Tyr) is exposed to the solvent.

Alkyl bromides are used as initiators in most of the atom transfer radical polymerization (ATRP) process and play an important role for controlling the ATRP equilibrium. In this work, the effect of solvent on equilibrium constant of ATRP ( K ATRP ) and rate constant of activation ( k act ) of three isomeric alkyl bromides [namely, N -phenyl(3-bromo-3-methyl)succinimide, N -phenyl(3-bromo-4-methyl)succinimide, and N -phenyl(3-bromomethyl)succinimide] is reported. The k act and K ATRP values of alkyl bromide are determined experimentally using UV–Vis-NIR spectrometry. The termination rate constant for model compound is calculated using DOSY NMR spectroscopy. The k act and K ATRP values for the mentioned alkyl bromides are determined in five different polar solvent and the effect of polarity is observed. The obtained values of k act and  K ATRP of N -phenyl(3-bromo-3-methyl)succinimide in acetonitrile at 25 °C is 6.60 × 10 −2  L mol −1  s −1 and 1.42 × 10 −9 , respectively. These values are quite comparable with the experimentally determined reported k act and K ATRP of values of acrylates and benzyls initiators. Alternatively, the investigation of possible chain initiation activity for the ATRP process for the mentioned alkyl bromides is carried out theoretically using density functional theory (DFT) method [B3LYP/6-31+G(d) level]. A good correlation is obtained between the experimentally determined and theoretically calculated K ATRP values of studied alkyl bromides in chosen solvents. Significantly, it is found that the values of k act and K ATRP of alkyl bromides is solvent dependent and the magnitude values of the k act and K ATRP increases with increasing the solvent polarity. The proposed bromo substituted succinimides can be used as the initiator for the polymerization of acrylates, benzyls, maleimides, and itaconimides monomer under the selected solvent system.

Oxidative degradation of o -, m - and p -cresols using ozone in the presence of V 2 O 5 -supported metal (Mn, Fe, Ni) catalysts was studied under ambient reaction conditions. Metal (Mn, Fe, Ni) loaded V 2 O 5 catalysts were prepared using a wet-impregnation method, thereafter, characterized, and analyzed by use of the XRD, FT-IR, SEM-EDX, TEM, and ICP-OES. Results show the effect of the amount of a metal that was loaded on the support, particularly, how it affects the resultant catalysts’ (i) crystallite size, (ii) dispersion of an active metal over the surface of a support, and (iii) catalytic activity. Mn-loaded catalysts were found to be relatively more active for the conversion of individual cresol isomers and the activity of this catalyst was significantly enhanced at a lower Mn to V 2 O 5 ratio (2.5 wt%). Mn(2.5 %)/V 2 O 5 catalyst led to conversions of 66.78, 71.01 and 73.68 % with o -, m -, and p -cresols respectively within 24 h of oxidation. Oxidation products were derivatized by ethanol and a few were positively detected using GC-MS. o -Tolyl acetate and 2,5-dihydroxy toluene were detected from o -cresol, m -tolyl acetate, and 2,3-dihydroxy toluene from m -cresol and p -tolyl acetate and 3,4-dihydroxy toluene from p -cresol oxidation. Dimethyl maleate and dimethyl oxalate were detected as common products in all three isomers’ oxidation.

Magical natural phenomena, human ingenuity and craftsmanship have evolved into the grand science of chemistry. The story of this process is described through a series of landmark developments: technical chemistry and chemical ideas in the Ancient World, natural philosophy in Ancient Greece, early chemical ideas and technology in Arabia, India and China, the rise of alchemy in Alexandria and its spread to Arabia and subsequently to Europe, the Chinese invention of gunpowder, the growth of alchemy in Europe and the alchemists’ quest to transmute base metals into gold, Michael Sendivogius and his trailblazing alchemical treatise which refocused alchemical investigations onto a new path, the demise of alchemy and its replacement by important new ideas, which were outlined by Robert Boyle during the middle of the seventeenth century.

The aim of chemical substitution is to replace hazardous chemicals with a less hazardous alternative in a certain product or process to make it safer for human health and the environment. While a lot has been done by researchers, industries and regulatory bodies on chemical substitution for safer products, very little has been reported in the field of safer processes. On the other hand, chemical substitution is one of the core principles of inherently safer design, a concept frequently used in the chemical industry for the prevention of major accidents. This work presents an analysis of implementing chemical substitution methodology for safer processes through inherently safer design. Chemical industries, nowadays, are frequently asked to phase out hazardous chemicals from their processes. This paper provides an insight into the issues and practicability of chemical substitution in processes with the help of case studies and a review of the existing frameworks of inherently safer design.

In this research work, the extraction, characterization, device fabrication, and theoretical investigation of Hibiscus sabdariffa plant extract, for possible application in solid DSSCs, are reported. The plant extract was analyzed using FT-IR and UV–Vis spectrophotometry. Polyaniline on graphene was used as the counter electrode whereas titanium (IV) oxide was used as the photo anode for the fabricated DSSCs. The experimental results obtained for the open circuit voltage, short circuit current density, field factor, maximum power and conversion efficiency are 0.925 V, 0.073 A/cm 2 , 1.43, 1.04 W, and 0.044 % respectively. The excited states of anthocyanin (delphinidin) and quercetin, the most stable structures of Hibiscus sabdariffa plant extract, were studied using density functional theory method. In addition, the theoretical open circuit voltage, light harvesting efficiency, coupling constant, free energy change, and HOMO–LUMO energy gap were predicted for the photovoltaic properties. The theoretical results suggest that quercetin has relatively better photovoltaic properties and, hence, potentially a better dye for solar cell application.