Structural and electron paramagnetic resonance (EPR) characterization of novel vanadium(V/IV) complexes with hydroquinonate-iminodiacetate ligands exhibiting "noninnocent" activity

Reaction of KVO3 with 2-[N,N′-(carboxymethyl)aminomethyl]-5-methylhydroquinone (H4mecah) in aqueous solution at pH 8.2 results in the isolation of mononuclear K2[VV(O)2{Hmecah(-3)}]·2H2O complex. On the other hand, reaction with the 2-[N,N′-(carboxymethyl)aminomethyl]-5-tert-butylhydroquinone (H4tbutcah) under the same conditions gives the tetranuclear mixed-valent complex K 6 [{V V O(μ-O)V IV O}{μ-tbutbicah(-6)}] 2·10.5H2O (H6tbutbicah, 2,2′-({2-[bis(carboxymethyl)amino]-3,6-dihydroxy-4-methylbenzyl}azanediyl)diacetic acid). The structures of both complexes were determined by single-crystal X-ray crystallography. The coordination environment of vanadium ions in both complexes is octahedral, with four out of the six positions to be occupied by the two cis carboxylate oxygens, one hydroquinonate oxygen, and one amine nitrogen atoms of the ligands' tripod binding sites. The importance of the chelate ring strains in the stabilization of the p-semiquinone radical is also discussed. A protonation of the ligated to vanadium(IV) ion hydroquinonate oxygen at low pH was revealed by continuous wave (cw) X-band electron paramagnetic resonance (EPR) and UV-vis spectroscopies

Ofloxacin Removal from Aqueous Media by Means of Magnetoactive Electrospun Fibrous Adsorbents

Functionalized electrospun polymer microfibrous membranes were fabricated by electrospinning and further surface-functionalized with magnetic iron oxide (FexOy) nanoparticles to yield magnetoactive nanocomposite fibrous adsorbents. The latter were characterized in respect to their morphology, mechanical properties and magnetic properties while they were further evaluated as substrates for removing Ofloxacin (OFL) from synthetic aqueous media and secondary urban wastewater (UWW) under varying physicochemical parameters, including the concentration of the pharmaceutical pollutant, the solution pH and the membranes’ magnetic content. The magnetic-functionalized fibrous adsorbents demonstrated significantly enhanced adsorption efficacy in comparison to their non-functionalized fibrous analogues while their magnetic properties enabled their magnetic recovery and regeneration

Evaluation of novel, cationic electrospun microfibrous membranes as adsorbents in bacteria removal

Electrospun microfibrous membranes comprised of poly(methyl methacrylate)-poly((2-diethylamino)ethyl methacrylate) random copolymers (PMMA-co-PDEAEMA) of various chemical compositions blended together with a commercially available PMMA have been fabricated with diameters between 4.0-6.4 μm and further evaluated as adsorbents for bacteria removal from aqueous media. The morphology and thermal stability of the membranes were determined by scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA), respectively. Tensile tests were also performed in order to investigate their mechanical properties. Membrane evaluation as adsorbents against two Gram-negative bacteria namely Pseudomonas aeruginosa and Advenella species revealed that the membranes containing the highest percentage of the cationic moieties (DEAEMA) exhibited the highest adsorption efficiency. The bacteria removal by the microfibrous membranes was studied by UV-vis spectrophotometry upon measuring the optical density (OD) of the microorganisms. The highest recorded bacteria removal percentages after 8 h were approximately 70% and 45%, for the Pseudomonas aeruginosa and Advenella species respectively, whereas in both cases complete (100%) bacteria removal was observed after 24 h of membrane immersion in bacteria-containing aqueous solutions. The experimental adsorption isotherms for P. aeruginosa and Advenella sp. were well-fitted with the Langmuir isotherm model indicating a monolayer adsorption process. SEM was also used to confirm the adhesion of the bacteria onto the electrospun microfibers. Most importantly, these materials exhibited great performance for the removal of microorganisms from urban wastewater as determined via the standard plating technique prepared by agar

Advanced nanomaterials in agriculture under a changing climate: The way to the future?

© 2020 Elsevier B.V. Global agricultural production is suffering substantial losses due to climate change-related phenomena such as drought and salinity, which lead to tissue damage and, ultimate, major yield losses. The development of sustainable, ‘green’ technologies is therefore becoming increasingly important. Nanotechnology provides invaluable tools to a variety of industrial sectors. Recent focus has been given to the development and optimization of nanomaterials for application in the agricultural industry towards improved growth, plant protection and overall performance based on their small size, high surface to volume ratio and unique optical properties. The present review provides an up-to-date description of advanced nanoparticles and polymers applied at plant and seed level, covering technical, biological and socioeconomical aspects of this promising approach. This technology offers an attractive alternative to established approaches such as conventional breeding and genetic modification with key advantages, representing a characteristic example of integrative plant physiology where multiple disciplines such as materials science, agriculture and analytical chemistry join forces to develop exciting new tools in modern agriculture

Binuclear VIV/V, MoVI and ZnII - hydroquinonate complexes: Synthesis, stability, oxidative activity and anticancer properties

Since the discovery of the anticancer properties of cis-platin the road for the development of less toxic and more specific metal ion based anticancer drugs has opened. Based on the low toxicity of VIV/V, MoVI and ZnII metal ions, their binuclear hydroquinonate complexes have been synthesized and their biological activity towards their anticancer properties on various cancerous and non-cancerous cell lines has been evaluated. The new complexes of ZnII with the ligands 2,5-bis((bis(pyridin-2-ylmethyl)amino)methyl)benzene-1,4-diol (H2bpymah) and 2,2'-(((2,5-dihydroxy-1,4-phenylene)bis(methylene))bis((carboxymethyl)ammoniumdiyl))diacetate (H6bicah) have been synthesized and characterized by X-ray crystallography in solid state and 1H NMR in aqueous solution. The binuclear nature of the complexes increases their hydrolytic stability in aqueous solutions at pD 7.0, depending on the metal ion. The most hydrolytic stable VV and ZnII hydroquinonate complexes show to activate O2 towards oxidation of mercaptoethanol in aqueous solutions at physiological pHs. Only the strongest oxidant, the VV complex with bicah6-, significantly activates the intracellular radical oxygen species (ROS) generation. Apparently, the mercaptoethanol oxidation experiment vs time can be used as a preliminary experiment for the prediction of the in vitro ROS generation activity of the complexes in aqueous solutions