Transition Metal Complexes as Antimalarial Agents: A Review

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Transition Metal Complexes as Antimalarial Agents: A Review

Herein we highlight recent progress in the field of metal-based antimalarial drug development. Based on transition metal series (3d, 4d, or 5d), the antimalarial metal complexes have been divided into three broad categories (3d, 4d, or 5d metal-based), and their activities have been compared with the similar control complexes as well as the parent drugs.


Abstract

In antimalarial drug development research, overcoming drug resistance has been a major challenge for researchers. Nowadays, several drugs like chloroquine, mefloquine, sulfadoxine, and artemisinin are used to treat malaria. But increment in drug resistance has pushed researchers to find novel drugs to tackle drug resistance problems. The idea of using transition metal complexes with pharmacophores as ligands/ligand pendants to show enhanced antimalarial activity with a novel mechanism of action has gained significant attention recently. The advantages of metal complexes include tunable chemical/physical properties, redox activity, avoiding resistance factors, etc. Several recent reports have successfully demonstrated that the metal complexation of known organic antimalarial drugs can overcome drug resistance by showing enhanced activities than the parent drugs. This review has discussed the fruitful research works done in the past few years falling into this criterion. Based on transition metal series (3d, 4d, or 5d), the antimalarial metal complexes have been divided into three broad categories (3d, 4d, or 5d metal-based), and their activities have been compared with the similar control complexes as well as the parent drugs. Furthermore, we have also commented on the potential issues and their possible solution for translating these metal-based antimalarial complexes into the clinic.

Impact of Ultrasound Treatment Duration on Dihydrate Precursor Implying the Sesquihydrate Route

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Impact of Ultrasound Treatment Duration on Dihydrate Precursor Implying the Sesquihydrate Route

Vanadium pentoxide was ultrasonic-treated to obtain the dihydrate precursor, which was subsequently reduced utilizing the sesquihydrate method before catalyst activation to provide improved vanadyl pyrophosphate active sites. The physicochemical characteristics, reactivity, and catalytic performance of the vanadium pentoxide catalysts that were synthesized are detailed.


Abstract

The present invention relates to a technique for synthesizing vanadium phosphorus oxide (VPO) catalyst employing an ultrasonic treatment approach while assessing phase composition and hydrocarbon oxidation activity to a conventionally synthesized catalyst. The ultrasonic treatment approach has been shown to produce a catalyst with improved surface constitution and accelerated hydrocarbon conversion in 3 h, as opposed to the typically heating process, which takes 24 h. Product selectivity is influenced by the nature of the catalyst, with an integration consisting of (VO)2P2O7 (V4+) and VOPO4 (V5+) being optimal for high rate of conversion. A 39 % conversion rate and 89 % maleic anhydride selectivity were achieved under optimum reaction conditions.

Electrodialysis with Irregular Membrane Spacers: Which is the Right Choice?

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Electrodialysis with Irregular Membrane Spacers: Which is the Right Choice?

Following the latest developments in membrane spacers for electrodialysis, this review article compares irregular spacers, such as Gyroid, tCLP, multilayered, crimped, and tortuous spacers, describing how these spacers affect the performance, efficiency, and fouling of membrane systems. The advantages and challenges of using irregular spacers for desalination and water treatment are presented.


Abstract

Membrane operations function well in turbulent conditions, requiring the use of a turbulence model. By increasing the velocity and generating eddies with membrane spacers, mass transport can be enhanced and permeability can be intensified while reducing concentration polarization. Spacers act as solid barriers for the bulk fluid and have been shown to facilitate mass transfer at channel thicknesses of 1 mm due to eddy promotion. Spacers are used in a variety of membrane processes including nanofiltration, reverse osmosis, electrodialysis, and membrane distillation. Membrane spacers can also be used for other applications such as membrane electrolysis, fuel cells, capacitive deionization, and electrodialysis with bipolar membranes. This work systematically reviews and compares irregular geometries of spacers, including Gyroid, tCLP, multilayered, crimped, and tortuous spacers. The review consistently concludes that the spacer geometrical properties are the primary determinants of the streamline effectiveness.

Chiral Purification of S‐Methyl‐2‐chloropropionate from Enantiomer Mixtures by Three‐Phase Crystallization

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Chiral Purification of S-Methyl-2-chloropropionate from Enantiomer Mixtures by Three-Phase Crystallization

Three-phase crystallization (TPC) was applied to purify S-methyl-2-chloropropionate (S-M2CP) from liquid enantiomer mixtures. TPC combines melt crystallization and vaporization to produce S-M2CP crystalline solid along with the vapor from the liquid feed via a series of three-phase transformations. The proposed model can be efficiently applied in the TPC process design and optimization.


Abstract

Three-phase crystallization (TPC) was applied to purify S-methyl-2-chloropropionate (S-M2CP) from liquid enantiomer mixtures with various initial concentrations. TPC combines melt crystallization and vaporization to produce the desired crystalline solid along with the vapor from the liquid feed via a series of three-phase transformations. The three-phase states during TPC were calculated in terms of the thermodynamic properties of M2CP. Basically, the liquid mixture was gradually transformed to the S-M2CP crystalline solid and vapor mixture at reduced temperature and pressure during TPC. A model was proposed based on the material and energy balances to determine the variations of the masses of the remained liquid mixture, of the produced S-M2CP crystalline solid, and of the produced vapor mixture during the batch TPC operation. The results indicated that the experimental yield and purity for the final S-M2CP product obtained during TPC were consistent with those predicted by the model.

Organic Semiconductor Interfaces and Their Effects in Organic Solar Cells

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Abstract

Energy levels and energy level alignment at interfaces play a decisive role in designing efficient and stable organic solar cells (OSCs). In this review two usually used technologies in organic photovoltaic communities for measuring energy levels of organic semiconductors, photoelectron spectroscopy and electrochemical methods, are introduced, and the relationships between the values obtained from the corresponding techniques are compared. The energy level and energy level alignment across the interfaces involved in solution processed organic photovoltaics are described, and the corresponding integer charge transfer model for predicting and explaining energy level alignment are presented. The effects of the interface properties in designing efficient binary and ternary OSCs were discussed. The effects of environmental factors mainly including water vapor, oxygen gas and thermal annealing on energy levels and energy level alignment involved in photoactive layers, and the subsequent effects on the corresponding OSC properties are given.

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Redox‐Responsive Macrocyclic Hosts Based on Calix[4]arene and Calix[4]resorcinarene Scaffolds

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Redox-Responsive Macrocyclic Hosts Based on Calix[4]arene and Calix[4]resorcinarene Scaffolds


Abstract

Calix[4]arenes and calix[4]resorcinarenes are well-known macrocyclic hosts that can be tailored to bind guests of very different natures, including anions, cations, and various neutral molecules. The molecular architectures of the hosts can be altered in many ways: by attaching polar or hydrophilic groups, extending inner cavities with enlarged aromatic side walls, and adding H-bonding sites to promote the formation of molecular capsules. The attachment of different types of redox-active moieties renders calix[4]arene and calix[4]resorcinarene derivatives electrochemically active, enabling them to either control the guest-binding properties of the receptors or be used as electrochemical sensors. This review will focus on calix[4]arene and calix[4]resorcinarene macrocyclic hosts with appended redox-active groups, such as ferrocene, tetrathiafulvalene, and quinone. We will discuss molecular receptors that can serve as redox sensors for cations or electron-deficient molecules or can bind and release their guests controlled by redox or electrochemical stimuli.