Synthesis of Mono‐, Di‐, Tri‐, and Tetra‐cationic Pyridinium and Vinylpyridinium Modified [2.2]Paracyclophanes: Modular Receptors for Supramolecular Systems

Posted on 12 March 2024 by

Modular Scaffolds for Supramolecular Systems: In this report, a new series of mono-, di-, tri-, and tetra-cationic pyridinium and vinylpyridinium modified [2.2]paracyclophanes (PCPs) is described. On N-methylation, the 3D PCPs bearing (cationic) pyridyl and vinylpyridinium functionalities have been demonstrated as efficient molecular receptors for application in supramolecular systems. The PCPs on grafting with light-responsive azobenzene (−N=N−) functional core as side-groups impart photosensitivity that can be remotely transformed on irradiation, offering photo-controlled smart molecular functions.

Abstract

In this report, a new series of mono-, di-, tri-, and tetra-cationic pyridinium and vinyl pyridinium-modified [2.2]paracyclophanes as useful molecular tectons for supramolecular systems are described. Regioselective functionalization at specific positions, followed by resolution step and successive transformations through Pd-catalyzed Suzuki-Miyaura and Mizoroki-Heck cross-coupling chemistry furnish a series of modular PCP scaffolds. In our proof-of-concept study, on N-methylation, the PCPs bearing (cationic) pyridyl functionalities were demonstrated as useful molecular receptors in host-guest supramolecular assays. The PCPs on grafting with light-responsive azobenzene (−N=N−) functional core as side-groups impart photosensitivity that can be remotely transformed on irradiation, offering photo-controlled smart molecular functions. Furthermore, the symmetrical PCPs bearing bi-, and tetra-pyridyl functionalities at the peripheries have enormous potential to serve as ditopic and tetratopic 3D molecular tectons for engineering non-covalent supramolecular assemblies with new structural and functional attributes.

Cross‐linked Triblock Peptide Capsules as Potential Oxygen Carriers

Posted on 12 March 2024 by

We report the synthesis of perfluorodecalin (PFD)-filled triblock peptide capsules. The capsules exhibit a suitable diameter, a certain mechanical strength, a large diffusion constant, fast gas exchange rates, and little cytotoxicity. Given the above advantages, these PFD-filled peptide capsules are very promising as potential artificial oxygen carriers.

Abstract

Perfluorodecalin (PFD)-filled capsules have been studied for over 15 years as artificial oxygen carriers. However, none of these capsules combines good biocompatibility, good mechanical stability and dispersion stability. Here we propose to use synthetic triblock peptides containing a central block of cysteine units as a cross-linking shell material for capsules with both good biocompatibility and stability. Together with outer aspartate units and inner phenylalanine units, the resulting amphiphilic triblock peptides can encapsulate PFD efficiently to prepare capsules with a suitable diameter, a certain mechanical strength, a large diffusion constant, fast gas exchange rates, and little cytotoxicity. Given the above advantages, these PFD-filled peptide capsules are very promising as potential artificial oxygen carriers.

Development and Characterization of Plant‐derived Aristatoside C and Davisianoside B Saponin‐loaded Phytosomes with Suppressed Hemolytic Activity

Posted on 11 March 2024 by

Phytosomal formulations of aristatoside C and davisianoside B compounds isolated from Cephalaria Aristata and Cephalaria davisina plants were prepared using the thin film hydration method. Physical characterization studies of the prepared phytosomal saponin formulation were carried out. The cytotoxic activity of phytosomal formulations was examined. The suppression of hemolytic activity of phytosomal formulations on erythrocytes caused by free saponins was investigated.

Abstract

Saponins are glycosides widely distributed in the plant kingdom and have many pharmacological activities. However, their tendency to bind to cell membranes can cause cell rupture, limiting their clinical use. In the previous study, aristatoside C and davisianoside B were isolated from Cephalaria species. Cytotoxicity assays showed that they are more active on A-549 cell lines than doxorubicin but caused hemolysis. In the current research, aristatoside C and davisianoside B were loaded to phytosomes called ALPs and DLPs respectively, and characterized for particle size, zeta potential, encapsulation efficiency, release kinetic, hemolytic activity, and cytotoxicity on A-549 cell line. DLPs maintained the cytotoxic activity of the free saponins against A-549 cells with IC50 of 9,64±0,02 μg/ml but dramatically reduced their hemolytic activity. Furthermore, temperature and time-dependent stability studies based on the size and zeta potential of ALPs and DLPs revealed that the phytosomes have sustained release properties over 2 weeks. Overall, DLPs displayed cytotoxicity against A-549 cells with minimal hemolysis and sustained release, highlighting their potential as nanotherapeutics for clinical applications.

A Computational Study of Photoinduced Borylation for Selected Boron Sources

Posted on 8 March 2024 by nKa Wa Fan, nHoi Ling Luk, nDavid Lee Phillipsn

The bis(catecholato)diboron(B₂cat₂) in dimethylacetamide (DMA) is popular boron source in photoinduced borylation. This article has studied the complex by DFT. It first compares the stoichiometry between the B₂cat₂ with 1 DMA and B₂cat₂ with 2 DMA. Based on the coordination of boron compound, two type of photoinduced borylation reaction mechanism were discussed and compared.

Abstract

This research article uses density functional theory (DFT) to study photoinduced borylation. This work examined the electron donor-acceptor complex (EDA) of bis(catecholato)diboron with different redox-active leaving groups and bis(pinacol)diboron with aryl N-hydroxyphthalimide. The results of these DFT studies show the complex ratio of B₂cat₂ and N, N-dimethylacetamide (DMA) should be 1 : 2 which is consistent with the experimental results in the literature. We further proposed a reaction mechanism and calculated the energies associated with each step.

A Fast HPLC/UV Method for Determination of Ketoprofen in Cellular Media

Posted on 8 March 2024 by

A simple, sensitive and quick HPLC method was developed for the determination of ketoprofen in cell culture media. Separation was performed using a gradient on a C18 column with a mobile phase of acetonitrile and acidified miliQ water. The method was validated for linearity, accuracy, precision, limit of quantitation, limit of detection, as well as for robustness. The described method is applicable for determination of various pharmacokinetic aspects of ketoprofen in vitro.

Abstract

A simple, sensitive and quick HPLC method was developed for the determination of ketoprofen in cell culture media (EMEM, DMEM, RPMI). Separation was performed using a gradient on the C18 column with a mobile phase of acetonitrile and miliQ water acidified by 0.1 % (v/v) formic acid. The method was validated for parameters including linearity, accuracy, precision, limit of quantitation and limit of detection, as well as robustness. The response was found linear over the range of 3–100 μg/mL as demonstrated by the acquired value of correlation coefficient R2=0.9997. The described method is applicable for determination of various pharmacokinetic aspects of ketoprofen in vitro.

Brownmillerite Calcium Ferrite, a Promising Perovskite‐Related Material in the Degradation of a Tight Dye under Ambient Conditions

Posted on 8 March 2024 by nZahra Noori, nAzim Malekzadeh, nJordi Poatern

Synthesized and characterized brownmillerite type Ca₂Fe₂O₅ nanoparticles degrade Alizarin Red S (ARS) quinone dye in the darkness, making it a promising material for the degradation of not only ARS but of other persistent dyes, too.

Abstract

Evaluation of effective and low-cost materials as catalysts to combat the threat of pollution is a significant and growing trend. With this aim, we have synthesized calcium ferrite brownmillerite by wet preparation approach as a catalyst for pollution. The structural analysis is established by the X-ray diffraction of Ca₂Fe₂O₅, whereas the tetrahedral and octahedral sites band stretching for ferrite specimen has been deduced using FTIR. The bandgap energy has been estimated by the Tauc relation (2.17 eV). Ca₂Fe₂O₅ brownmillerite exhibits a BET surface area of 10 m²/g and a BJH pore volume of 0.121 cm³/g with the average particle size of 70 nm. Importantly, the alizarin Red S dye degradation has been studied using the prepared ferrite catalyst, under dark ambient conditions and without the presence of any acidic or basic additives. Degradation is also supported by both FTIR and TOC analysis. Surface properties of brownmillerite Ca₂Fe₂O₅ have been characterized using electronic spectroscopy and CO₂ temperature programmed desorption (TPD) analysis and revealed that the basic surface of brownmillerite Ca₂Fe₂O₅ offers active sites that are suitable for degradation processes. All results show that the preparation of brownmillerite Ca₂Fe₂O₅ via the Pechini method is suitable to produce fine surfaces and pores with nanosized particles.

Intramolecular CH‐Hydrogen Bonding During the Dissociation of the Oxaphosphetane Intermediate Facilitates Z/E‐Selectivity in Wittig Olefination

Posted on 8 March 2024 by nKukkamudi Sreenivas, nChintada Nageswara Rao, nFaiz Ahmed Khann

The Z-selective synthesis of novel nitrostilbenes has been reported. An intrinsic role of intramolecular hydrogen bonding during the dissociation of OPA-intermediate is critical for the stereoselective Wittig olefination. DFT calculations and X-ray measured intramolecular CH hydrogen bonding distances strongly support the observed phenomenon. Further, the current methodology has been utilized to synthesize medicinally potential salicylate-methyl-ester-based 2-arylindole derivatives.

Abstract

Herein, DFT studies corroborating experimental results revealed that the shortest intramolecular hydrogen bonding distance of cis/trans-oxaphosphetane (OPA) oxygen with the CH-hydrogen of a triphenylphosphine phenyl ring provides good evidence for the attained olefin Z/E-selectivity in Wittig olefination of the studied examples. 2-Nitrobenzaldehyde, 3-nitrobenzaldehyde, 2-nitro-3-bromobenzaldehyde, 2-nitro-5-bromobenzaldehyde and 2-nitro-5-arylbenzaldehydes provided Z-nitrostilbenes with (2-chloro-4-hydroxy-3-methoxy-5-(methoxycarbonyl)benzyl) triphenylphosphonium chloride as the major products. However, 4-nitrobenzaldehyde and 2-nitro-6-bromobenzaldehydes furnished E-nitrostilbenes as the major products in high yields. Furthermore, the DFT computed intramolecular CH1/CH2-hydrogen bond distances with Cl/NO₂ of selected stilbene derivatives were in good agreement with intramolecular hydrogen bond distances measured from single-crystal X-ray diffraction measurements.

Front Cover: (ChemistryOpen 3/2024)

Posted on 8 March 2024 by Wiley: ChemistryOpen: Table of Contents

Unraveling the Mechanism of Doping Borophene

Posted on 8 March 2024 by

The nitrogen doping mechanism into borophene is investigated. The sp ² orbitals of boron atoms in alternative triangular motifs are responsible for arranging themselves to accommodate the electron of N atom. While heavier atoms (Fe, Co, Ni) distort the local geometry of borophene, the lighter atoms (C, N, O) get rearranged.

Abstract

We elucidate the doping mechanism of suitable elements into borophene with first-principles density functional theory calculation. During doping with nitrogen (N), the sp ² orbitals are responsible for arranging themselves to accommodate the electron of the N atom. Doping dramatically changes structure and electronic properties from corrugated and metallic borophene to flat and insulating h-BN with 100 % N-doping. We extend the mechanism of N-doping in borophene to doping of non-metallic and metallic ad-atoms on borophene. Our findings will help to design boron-based 2D materials.

Study of Cytotoxic and Antibacterial Activity of Ag‐ and Mg‐Dual‐Doped ZnO Nanoparticles

Posted on 8 March 2024 by

A simple process for the fabrication of silver and magnesium dual doped Zinc oxide nanoparticles (Ag/Mg−ZnO NP) is described, which were studied for their anti-bacterial effect towards Streptococcus mutans bacteria, as well as for their cytotoxic activity on a breast cancer (MDA-MB-231) cell line. In light of the collected toxicity and antibacterial data as a compared between the doped and native nanoparticles, the applicability of Ag/Mg−ZnO NP in dental and medical sciences is proposed.

Abstract

A non-laborious process for the fabrication of silver and magnesium dual doped zinc oxide nanoparticles (Ag/Mg−ZnO NP) is described. The wurtzite ZnO nano-structures and the dual doped NP were analyzed by PXRD. SEM data showed the hexagonal morphology of our product, while the gathered anti-bacterial outcomes towards Streptococcus mutans bacteria through micro-dilution technic affirmed the enhanced performance of doped NP compared to the native ones. Furthermore, we gauged the toxic impacts of synthesized pure and Ag/Mg−ZnO NP against a breast cancer (MDA-MB-231) cell line through an MTT trial, which highlighted the superiority of the doped when compared to the native nanoparticles. In light of these comparisons, the applicability of Ag/Mg−ZnO NP in dental and medical science is proposed.