Search results for "14"
showing 10 items of 9841 documents
Solid state halogen bonded networks vs. dynamic assemblies in solution: explaining N⋯X interactions of multivalent building blocks
2015
Tetrapyridine functionalized resorcinarene macrocycles were used as multivalent building blocks for the construction of halogen bonded networks with aryl halide linkers. In the solid state, resorcinarene macrocycles and aryl halide linker molecules assembled into interpenetrated, multidimensional halogen bonded networks with porous structure caused by the 3D block scaffold of the resorcinarenes. 19F NMR spectroscopy proved halogen bond formation also in solution, as either upfield or downfield shifts were observed depending on the bivalent or monovalent halogen bond binding mode. The binding mode in solution was explained by density functional theory computations. peerReviewed
Potent SARS-CoV-2 mRNA Cap Methyltransferase Inhibitors by Bioisosteric Replacement of Methionine in SAM Cosubstrate
2021
Viral mRNA cap methyltransferases (MTases) are emerging targets for the development of broad-spectrum antiviral agents. In this work, we designed potential SARS-CoV-2 MTase Nsp14 and Nsp16 inhibitors by using bioisosteric substitution of the sulfonium and amino acid substructures of the cosubstrate S-adenosylmethionine (SAM), which serves as the methyl donor in the enzymatic reaction. The synthetically accessible target structures were prioritized using molecular docking. Testing of the inhibitory activity of the synthesized compounds showed nanomolar to submicromolar IC50 values for five compounds. To evaluate selectivity, enzymatic inhibition of the human glycine N-methyltransferase invol…
Numerical model for composite material with polymer matrix reinforced by carbon nanotubes
2008
Due to the high stiffness and strength, as well as their ability to act as conductors, carbon nanotubes are under intense investigation as fillers in polymeric materials. The nature of the carbon nanotube/polymer bonding and the curvature of the carbon nanotubes within the polymer have arisen as particular factors in the efficacy of the carbon nanotubes to actually provide any enhanced stiffness or strength to the nanocomposite. Here the effects of carbon nanotube curvature and interface interaction with the matrix on the nanocomposite stiffness are investigated using nanomechanical analysis. In particular, the effects of poor bonding and thus poor shear lag load transfer to the carbon nano…
A numerical-analytical model for the characterization of composites reinforced by carbon nanotubes
2010
A mixed model, numerical-analytical, is presented that allows one to predict the elastic properties of carbon nanotube (CNT)/polymer composites containing a random distribution of CNTs, while taking account of the curvature that they show when immersed in the polymer. This hybrid approach is a significant advance over micromechanical modeling and can be applied to all nanostructured composites.
Halogen bonding enhances nonlinear optical response in poled supramolecular polymers
2015
We demonstrate that halogen bonding strongly enhances the nonlinear optical response of poled supramolecular polymer systems. We compare three nonlinear optical chromophores with similar electronic structures but different bond-donating units, and show that both the type and the strength of the noncovalent interaction between the chromophores and the polymer matrix play their own distinctive roles in the optical nonlinearity of the systems. acceptedVersion Peer reviewed
Organic derivatives of mercury and tin as promoters of membrane lipid peroxidation.
2008
The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement …
Investigation on the indentation behavior of sandwich beams using crushable and hyperelastic foam cores
2010
In this work the indentation behaviour of sandwich beams is studied adopting the classical approach representing the core material as a Winkler-type foundation. It is shown how most of the proposed theories can be derived from a general fourth order linear differential equation expressing the equilibrium of the indented beam skin. Different assumptions on the supporting boundary constraints and materials constitutive behaviour, lead to simplifications of the general equation and to the prediction of different indentation features. An extension of the Segment-Wise approach recently proposed in the literature is in particular presented with potential to better simulate foam cores with markedl…
N-Alkyl ammonium resorcinarene polyiodides
2016
Four N-alkyl ammonium resorcinarene halides incorporating polyiodides were obtained and structurally analyzed by single crystal X-ray crystallography. The unexpected formation of triiodides and pentaiodide anions in these structures was assumed to be the result of the heterolytic dissociation of molecular iodine (I2) in the presence of electron donors in the N-alkyl ammonium resorcinarene halide system, from which I− further binds one or two I2 molecules resulting in I3− or I5− species, respectively.
Recognition of Viologen Derivatives in Water by N-Alkyl Ammonium Resorcinarene Chlorides
2017
Three water-soluble N-alkyl ammonium resorcinarene chlorides decorated with terminal hydroxyl groups at the lower rims were synthesized and characterized. The receptors were decorated at the upper rim with either terminal hydroxyl, rigid cyclohexyl, or flexible benzyl groups. The binding affinities of these receptors toward three viologen derivatives, two of which possess an acetylmethyl group attached to one of the pyridine nitrogens, in water were investigated via 1H NMR spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry (ITC). ITC quantification of the binding process gave association constants of up to 103 M–1. Analyses reveal a spontaneous binding process whi…
Cationic Au Nanoparticle Binding with Plasma Membrane-like Lipid Bilayers: Potential Mechanism for Spontaneous Permeation to Cells Revealed by Atomis…
2014
Despite being chemically inert as a bulk material, nanoscale gold can pose harmful side effects to living organisms. In particular, cationic Au nanoparticles (AuNP+) of 2 nm diameter or less permeate readily through plasma membranes and induce cell death. We report atomistic simulations of cationic Au nanoparticles interacting with realistic membranes and explicit solvent using a model system that comprises two cellular compartments, extracellular and cytosolic, divided by two asymmetric lipid bilayers. The membrane-AuNP+ binding and membrane reorganization processes are discovered to be governed by cooperative effects where AuNP+, counterions, water, and the two membrane leaflets all contr…