Mononuclear High-spin Octahedral Cobalt(II) Complex with Positive Axial Magnetic Anisotropy: Synthesis,Crystal Structure,and DFT Studies

This article outlines the magnetic features of a new six–coordinate high-spin cobalt(II) complex cis-[Co^II(tmphen)₂(NCS)₂] ( 1 ) achieved via the reactions of cobalt(II) thiocyanate with 3,4,7,8-tetramethyl-1,10-phenanthroline. The complex 1 was thoroughly characterized by different analytical and spectroscopic techniques and further confirmed by single X-ray crystal diffraction pattern. Complex 1 is a neutral molecule and adopt highly distorted six-coordinate CoN₆ octahedral coordination sphere surrounded by two thiocyanate N atoms in cis locations and the equatorial plane is occupied by two imine N atoms from the two tmphen ligand while the remaining two imine N atoms reside in the axial positions. Magnetic susceptibility data of complex 1 revealed that the χ_ΜT values decrease significantly to a value of 1.49 cm³ · K · mol^–1 at 2.0 K on decreasing temperatures below 100 K, mainly ascribed to the significant spin–orbit coupling (SOC) of six-coordinate Co^II ions. Furthermore, a field-dependence measurement was performed at 2 K, which shows a positive curvature up to 27 kOe, while it becomes linear up to 2.01 Nμ_B, which authenticated the fact that only the lowest Kramers doublet of ground state is appreciably populated.     

Catalytic activity of Mn(III) and Co(III) complexes: evaluation of catechol oxidase enzymatic and photodegradation properties

We have synthesized two mononuclear complexes, Mn-hq and Co-hq, to serve as sustainable catalysts (for degrading dyes from organic pollutant) and as biocatalysts (for promoting oxidation of catechol to quinone). The two complexes have been characterized by various spectroscopic tools, and with the assistance of single-crystal X-ray diffraction data, their molecular structures were established. The present complexes were exploited for the catalytic activity, i.e., enzymatic activity and photocatalytic property. In methanolic solution, Mn-hq and Co-hq were examined for catecholase-like activity and Mn-hq particularly catalyzes the oxidation of 3,5-di-tert-butyl catechol to analogous quinone with a K_cat value of 835.2 h^?1. Additionally, Mn-hq and Co-hq demonstrated remarkable photocatalytic activity for the degradation of methylene blue (MB) in the aqueous medium beneath visible light. Co-hq shows excellent stability and recyclability toward MB. Further, trapping experiment along with degradation pathways is also explored. Thus, the present research throws light on the excellent catalytic properties of simply designed complexes and this activity can be tuned for desired efficiencies in future prospects.

     

An efficient and novel protocol for the synthesis of spiro[1,3]oxazino[5,6-c]quinoline derivatives by one-pot,three-component reaction

Research on Chemical Intermediates - One-pot, three-component reaction of various aryl glyoxal monohydrates, 5-methylisoxazol-3-amine and 4-hydroxyquinolin-2(1H)-one in the presence of a catalytic...     

Current understanding of catalyst/ionomer interfacial structure and phenomena affecting the oxygen reduction reaction in cathode catalyst layers of proton exchange membrane fuel cells

To improve the performance of membrane electrode assemblies used in proton exchange membrane fuel cells, a better understanding is necessitated regarding the nano/microstructure of the catalyst layer and the physicochemical phenomena responsible for the oxygen reduction reaction (ORR) occurring on this layer. In particular, it is very important to understand catalyst/ionomer interfaces in the cathode catalyst layer to apply the advanced ORR catalysts to the cathode catalyst layer in membrane electrode assemblies, which have solid-phase electrolytes; these catalysts are primarily developed under liquid electrolyte conditions. A closer observation of the catalyst/ionomer interfacial structure shows that all the transport processes required for ORR are controlled by the ionomer thin film covering the catalyst. Therefore, this review addresses this issue and introduces recent studies on catalyst/ionomer interfaces. We discuss the current understanding of the structure of the catalyst/ionomer interface, which depends on the surface characteristics of the catalyst and the ionomer, as well as transport of water, ions, and gas; these factors are in turn dependent on the structure of the interface. In addition, we introduce research efforts for improving the properties of catalyst inks, which form the basis for controlling the catalyst/ionomer interfacial structure. Based on the findings of these studies, we propose further opportunities and challenges in the study of catalyst/ionomer interfaces.     

Deciphering the Role of Filamin B Calponin-Homology Domain in Causing the Larsen Syndrome,Boomerang Dysplasia,and Atelosteogenesis Type I Spectrum Disorders via a Computational Approach

Filamins (FLN) are a family of actin-binding proteins involved in regulating the cytoskeleton and signaling phenomenon by developing a network with F-actin and FLN-binding partners. The FLN family comprises three conserved isoforms in mammals: FLNA, FLNB, and FLNC. FLNB is a multidomain monomer protein with domains containing an actin-binding N-terminal domain (ABD 1–242), encompassing two calponin-homology domains (assigned CH1 and CH2). Primary variants in FLNB mostly occur in the domain (CH2) and surrounding the hinge-1 region. The four autosomal dominant disorders that are associated with FLNB variants are Larsen syndrome, atelosteogenesis type I (AOI), atelosteogenesis type III (AOIII), and boomerang dysplasia (BD). Despite the intense clustering of FLNB variants contributing to the LS-AO-BD disorders, the genotype-phenotype correlation is still enigmatic. In silico prediction tools and molecular dynamics simulation (MDS) approaches have offered the potential for variant classification and pathogenicity predictions. We retrieved 285 FLNB missense variants from the UniProt, ClinVar, and HGMD databases in the current study. Of these, five and 39 variants were located in the CH1 and CH2 domains, respectively. These variants were subjected to various pathogenicity and stability prediction tools, evolutionary and conservation analyses, and biophysical and physicochemical properties analyses. Molecular dynamics simulation (MDS) was performed on the three candidate variants in the CH2 domain (W148R, F161C, and L171R) that were predicted to be the most pathogenic. The MDS analysis results showed that these three variants are highly compact compared to the native protein, suggesting that they could affect the protein on the structural and functional levels. The computational approach demonstrates the differences between the FLNB mutants and the wild type in a structural and functional context. Our findings expand our knowledge on the genotype-phenotype correlation in FLNB-related LS-AO-BD disorders on the molecular level, which may pave the way for optimizing drug therapy by integrating precision medicine.     

Fabrication and characterization of a novel wound scaffold based on polyurethane added with Channa striatus for wound dressing applications

Abstract

Wound healing is a complex process and it involves restoration of damaged skin tissues. Several wound dressings comprising naturally made substances are constantly investigated to assist wound healing. In this research, a new wound dressing based on polyurethane (PU) supplemented with essence of Channa striatus (CS) fish oil was made by electrospinning. Morphological study depicted the reduction in fiber diameter than PU with the addition of fish oil (0.552?±?0.109?μm for 8:1 v/v% and 0.519?±?0.196?μm 7:2 v/v%) than the pristine PU (0.971?±?0.205?µm). Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of fish oil in the composite as identified through increasing peak intensity. Fish oil resulted in the hydrophilic behavior (88?±?3 (8:1 v/v) and 70?±?6 (7:2 v/v)) as revealed in the contact angle analysis. Thermal gravimetric analysis (TGA) showed the superior thermal behavior of the wound dressing patch compared to the PU. Atomic force microscopy (AFM) analysis insinuated a decrease in the surface roughness of the pristine polyurethane with the added fish oil. Coagulation assays signified the delay in the blood clotting time portraying its anti-thrombogenic behavior. Hemolytic assay revealed the less toxic nature of the developed nanocomposites with the red blood cells (RBC’s) depicting its safety with blood. Hence, polyurethane nanofibers supplemented with fish oil made them as deserving candidates for wound dressing application.     

High Na+ Mobility in rGO Wrapped High Aspect Ratio 1D SbSe Nano Structure Renders Better Electrochemical Na+ Battery Performance

We chose to understand the cyclic instability and rate instability issues in the promising class of Na⁺ conversion and alloying anodes with Sb₂Se₃ as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb₂Se₃ material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g⁻¹ at a specific current of 100 mA g⁻¹ and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag⁻¹ intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb₂Se₃-rGO) compared to bare Sb₂Se₃. GITT analysis reveals higher Na⁺ diffusion coefficients (approx. 30 fold higher) in the case of Sb₂Se₃-rGO as compared to bare Sb₂Se₃ throughout the operating voltage window. For Sb₂Se₃-rGO the diffusion coefficients in the range of 8.0×10⁻¹⁵ cm² s⁻¹ to 2.2×10⁻¹² cm² s⁻¹ were observed, while in case of bare Sb₂Se₃ the diffusion coefficients in the range of 1.6×10⁻¹⁵ cm² s⁻¹ to 9.4×10⁻¹⁵ cm² s⁻¹ were observed.     

Chromatographic identification of “green capping agents” extracted from Nasturtium officinale (Brassicaceae) leaves for the synthesis of MoO3 nanoparticles

A low‐temperature, efficient and effective method was investigated for phytochemical hydroethanolic extraction of Nasturtium officinale (Brassicaceae). The phytocompounds of the selected plant leaves were identified by high‐performance liquid chromatography, gas chromatography with mass spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet‐visible spectroscopy. Acetic acid, d ‐alanine, octodrine, decanoic acid, and cyclohexylethylamine were the major phytocompounds identified in N. officinale leaves with high similarity match and spectral purity. The reducing and stabilizing potential of the extracted phytochemicals was demonstrated by synthesizing the metal oxide nanoparticles (MoO₃) by treating ammonium heptamolybdate tetrahydrate (H₄MO₇N₆O₂₄.4H₂O) aqueous complex with bioactive compounds of the leaves. The bio‐synthesized MoO₃ nanoparticles were characterized by ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, energy dispersive X‐ray spectroscopy, field emission‐scanning electron microscopy, and gas chromatography with mass spectroscopy. Gas chromatography‐mass spectroscopy identified acetic acid, d ‐alanine, and octodrine as stabilizing agents in the synthesis of MoO₃ nanoparticles.     

Effect of shell thickness on the temperature-sensitive property of core-shell composite polymer particles

Core-shell composite polymer particles having temperature-sensitive shell were prepared by seeded emulsion copolymerization of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate (EGDM) with 0.14 μ-sized polystyrene seed particles according to our previous article. In this article, the effects of crosslinking density and thickness of the shell on the temperature-sensitive property were studied. Two series of composite particles, one with various EGDM contents in the shell and the other with various shell contents, were prepared for this study. The composite particles at the EGDM content of 3 wt % with the shell content of 47 wt %, showed the maximum swelling and deswelling phenomena at temperatures, respectively, below and above the lower critical solution temperature. The adsorption and desorption behaviors of low molecular weight cationic emulsifier and bio-molecules were dependent on the shell content. In almost all cases, the adsorption/desorption behavior reached to the maximum variations at the shell content of 17 wt %. © 1996 John Wiley & Sons, Inc.