Charge transfer and opto-electronic properties of some newly designed polycatenar discotic liquid crystal derivatives: a DFT study

Hydrogen production and storage through adsorption and dissociation of H2O on pristine and functionalized SWCNT: a DFT approach

CONTEXT

Adsorption of 1 and 2 H2O molecules for hydrogen production and storage on the surface of pristine, carbamic acid and 2-amino 3-acetylpyridine functionalized SWCNTs with the dimensionality of (2, 4), (5, 5), and (6, 0) at various positions, i.e., center and edges were investigated by using computational DFT calculations. Adsorption energies and structural and electronic parameters were determined for pristine and functionalized SWCNTs with four different H2O orientations. Functionalization of 2-amino 3-acetylpyridine resulted in more favorable adsorption energies for 1 and 2 H2O molecules splitting as compared to spitting on pristine and carbamic acid functionalized SWCNT. Calculated adsorption constant, Kad confirmed greater binding interactions of functionalized SWCNTs with 1 and 2 H2O molecules as compared to pristine SWCNT. Isosurface for the adsorption of 1 and 2 H2O molecules on pristine and functionalized SWCNTs elaborated altered electrophilic and nucleophilic character. Effect of H2O concentration was monitored to determine hydrogen storage capacity which was found to be 7.17 wt.% for thirty molecules. An important finding of study is production of Stone-Wales (SW) defect upon H2O adsorption leading to increase in hydrogen production and its storage capacity. The functionalization of topological defected SWCNTs provides distinctive applications of CNTs for gas storage purposes.t: METHODS: In the current study, First Principal Density Functional Theory (DFT) calculations were carried which provides greater computational efficiency as compared to many traditional quantum mechanical methods. SCME: ADF (2018) modeling suite software with in framework of DFT approach using exchange correlation (XC) LDA-GGA (Generalized Gradient Approximation) with PBE (Perdew, Burke and Ernzerhof) functional and DZ (Double beta) basis set was employed to investigate structural, energetic and electronic aspects of adsorption on the surface of pristine, carbamic acid and 2-amino 3-acetly pyridine functionalized SWCNTs. (2, 4), (5, 5) and (6, 0) SWCNTs were designed using Avogadro's software and were imported to SCM: ADF graphical interface and were optimized as adsorbent. Single point energy (SPE), geometry optimization and high accuracy frequency calculations were performed to determine energetic, electronic and thermodynamic characteristics and feasibility of adsorption using XC of GGA-PBE functional & DZ basis set.

Phase transitions and topological defects in discotic liquid crystal droplets with planar anchoring: a Monte Carlo simulation study

In this work we present the results of Monte Carlo (MC) simulations at the isothermal-isobaric ensemble for a discotic liquid crystal (DLC) droplet whose surface promotes edge-on (planar) anchoring. For a given pressure, we simulate an annealing process that enables observation of phase transitions within the spherical droplet. In particular, we report a first order isotropic-nematic transition as well as a nematic-columnar transition at the center of the droplet. We found the appearance of topological defects consisting of two disclination lines with ends at the surface of the sphere. We also observed that both transitions, isotropic-nematic and nematic-columnar, occur at lower temperatures as compared to the unconfined system.

Appraisal of novel azomethine-thioxoimidazolidinone conjugates as ecto-5'-nucleotidase inhibitors: synthesis and molecular docking studies

Purinergic signaling is regulated by a group of extracellular enzymes called ectonucleotidases. One of its members i.e., ecto-5′-nucleotidase (h-e5′NT) is involved in the final step of the enzymatic hydrolysis cascade that is the conversion of adenosine monophosphate (AMP) to adenosine and therefore, involves the regulation of adenosine level in extracellular space. The overexpression of h-e5′NT has been observed in various pathological conditions such as hypoxia, inflammation and cancers, and led to various complications. Hence, the identification of a potent as well as selective inhibitor of h-e5′NT is of greater importance in therapeutic treatment of various diseases. Azomethine-thioxoimidazolidinone derivatives were studied for their inhibition potential against e5′NT enzyme along with cytotoxic potential against cancer cell lines possessing overexpression of e5′NT enzyme. The derivative (E)-3-((4-((3-methoxybenzyl)oxy)benzylidene)amino)-2-thioxoimidazolidin-4-one (4g) displayed selective and significant inhibition towards h-e5′NT with an IC₅₀ value of 0.23 ± 0.08 μM. While two other derivatives i.e., (E)-3-(((5-bromothiophen-2-yl)methylene)amino)-2-thioxoimidazolidin-4-one (4b) and 2-thioxo-3-((3,4,5-trimethoxybenzylidene)amino)imidazolidin-4-one (4e), exhibited non-selective potent inhibitory behavior against both human and rat enzymes. Moreover, these derivatives (4b, 4e and 4g) were further investigated for their effect on the expression of h-e5′NT using quantitative real time polymerase chain reaction. Additionally, molecular docking and DFT studies were also performed to determine the putative binding mode of potent inhibitors within the enzyme active site. HOMO, LUMO, ΔE, and molecular electrostatic potential maps were computed by DFT and the charge transfer regions within the molecules were identified to find out the regions for electrophilic and nucleophilic attack.

Azomethine–thioxoimidazolidinone conjugates as ecto-5′-nucleotidase inhibitors.