Experimental and theoretical investigation of new 1,3,4-oxadiazole based dioxovanadium (VO+2) complexes and their in-vitro antimicrobial potency

The antimicrobial resistance is a global human threat which has led to the withdrawal of antibiotics from the market. Therefore, it is a need to develop new and effective antimicrobial agents to overcome this problem. In this paper, new Dioxovanadium(V) complexes (1–8) with ligands viz. (2-(5-phenyl-1,3,4-oxadiazole-2-yl)phenol; L1) and 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole (L2) were synthesized and assessed for antimicrobial-activity. Both a bidentate and tetradentate oxadiazole ligands coordinate with vanadium ions through the nitrogen and oxygen atoms giving octahedral geometries. Thermal analysis and IR data confirmed the presence of hydrated water in the metal-complexes. The investigated compounds were assessed for antimicrobial viz four strains of bacterial and one a fungal strain. The antibacterial data showed that, the complexes (1–8) are lower potency against bacterial strain than the free ligands except (5) and (7) complexes. These complexness showed the highest antibacterial potency via the Staphylococcus aureus. All investigated compounds were inactive against C. albicans except complexes 2 and 5 which showed high activity. The performance of DFT was conducted to examine an interaction mode of the target compounds with biological system. The QSPR was calculated as: optimization geometries, (FMOs), and chemical-reactivities for the synthesized compounds. The (MEPs) were figured to predict the interaction behavior of the ligand and its complexes against the receptor. The molecular docking was performed against DNA gyrase to study the interaction mode with biological system.

Capacity balancing for vanadium redox flow batteries through continuous and dynamic electrolyte overflow

The vanadium crossover through the membrane can have a significant impact on the capacity of the vanadium redox flow battery (VFB) over long-term charge–discharge cycling. The different vanadium ions move unsymmetrically through the membrane and this leads to a build-up of vanadium ions in one half-cell with a corresponding decrease in the other. In this paper, a dynamic model is developed based on different crossover mechanisms (diffusion, migration and electro osmosis) for each of the four vanadium ions, water and protons in the electrolytes. With a simple to use approach, basic mass transport theory is used to simulate the transfer of vanadium ions in the battery. The model is validated with own measurements and can therefore predict the battery capacity as a function of time. This is used to analyse the battery performance by applying an overflow from one half-cell to the other. Different constant overflow rates were analysed with regard to an impact of the performance and electrolyte stability. It was observed that a continuous overflow increases the capacity significantly but that the electrolyte stability plays an essential role using a membrane with a big vanadium crossover. Even with a good performance, a complete remixing of the tanks is necessary to prevent electrolyte precipitations. Therefore, a dynamic overflow was determined in such a way that the capacity of the battery is maximised while the electrolytes remain stable for 200 cycles. Graphic abstract

Microfluidic-like Fabrication of a Vanadium-Cured Bioadhesive by Mussels

<p>To anchor in seashore habitats, mussels fabricate adhesive byssus fibers mechanically reinforced by protein-metal coordination mediated via 3,4-dihydroxyphenylalanine (DOPA) – providing a well-established role model for bio-inspired design of smart metallopolymers and underwater glues. However, currently, the mechanism by which metal ions are integrated as cross-links during byssus formation is completely unknown. Here, we investigated the byssus formation process, combining traditional and advanced methods to identify how and when metals are incorporated into the material. We discovered that mussels concentrate and store iron and vanadium ions in intracellular metal storage particles (MSPs) complexed with previously unknown catechol-based storage molecules. During thread formation, stockpiled secretory vesicles containing concentrated fluid proteins are mixed with MSPs within a complex microfluidic-like network of interconnected channels where they coalesce forming protein-metal bonds within the nascent byssus. These insights are important for bio-inspired materials design, but also from a biological and chemical perspective – the active accumulation and utilization of vanadium is extremely rare in nature.</p>

Microfluidic-like Fabrication of a Vanadium-Cured Bioadhesive by Mussels

<p>To anchor in seashore habitats, mussels fabricate adhesive byssus fibers mechanically reinforced by protein-metal coordination mediated via 3,4-dihydroxyphenylalanine (DOPA) – providing a well-established role model for bio-inspired design of smart metallopolymers and underwater glues. However, currently, the mechanism by which metal ions are integrated as cross-links during byssus formation is completely unknown. Here, we investigated the byssus formation process, combining traditional and advanced methods to identify how and when metals are incorporated into the material. We discovered that mussels concentrate and store iron and vanadium ions in intracellular metal storage particles (MSPs) complexed with previously unknown catechol-based storage molecules. During thread formation, stockpiled secretory vesicles containing concentrated fluid proteins are mixed with MSPs within a complex microfluidic-like network of interconnected channels where they coalesce forming protein-metal bonds within the nascent byssus. These insights are important for bio-inspired materials design, but also from a biological and chemical perspective – the active accumulation and utilization of vanadium is extremely rare in nature.</p>