Simulations show that the total volatile basic amines (TVB) from spoiled fish can be sensed by aziridine-functionalized graphene nanomaterials to induce substantial changes in the physical properties.

Anthropogenic activities presently generate undesirable industrial and house waste byproducts such as heavy metallic cations (HMCs), which are then often released into the environment, despite being harmful to human beings. Developing new materials that can detect and capture HMCs is therefore highly desirable for wastewater remediation, especially if using cheap starting raw materials such as carbon. To shed theoretical light in this direction, we use density functional theory simulations to study the functionalization of pristine graphene with prototypical carbenes, RC(O)CH, with R = −OCH 3 (2a), −OH (2b), −ONa (2c), and −Ph (2d), and explore their use in sensing and capturing toxic HMCs (here, we focus on the most common and harmful ones: Cd 2+ , Hg 2+ , and Pb 2+ ). We first demonstrate that, starting from activated diazomethanes, RC(O)CHN 2 (1a−d), and graphene as precursors, it is possible to yield substituted cyclopropanes tethered to graphene, here modeled as a 6 × 6 supercell (g6×6), via a [2 + 1]cycloaddition reaction. Projected density of states and band structure calculations show that the cycloaddition reaction induces a band gap opening of the graphene, which can be used to tune it for electronic sensing devices. These nanomaterials (g6×6/3a−d) favorably interact with the metallic cations through coordination bonds with interaction energies varying from −1.18 to −2.75 eV. Differences in the electronic charge density following HMC adsorption reveal regions of electron depletion or gain induced by these interactions. Based on energetic and electronic structure analysis, we suggest that g6×6/3b−d are good candidates to detect HMCs. All the four nanomaterials show a higher affinity toward Pb 2+ , as rationalized by a synergic interaction with the graphene substrate, suggesting that they can be used for Pb 2+ sensing and removal. Notably, we demonstrate that once and only once the proper computational approach is employed, the accuracy of our predictions of a larger interaction strength of Pb 2+ with respect to Cd 2+ is validated via the agreement with available experimental data on g6×6/3b. Finally, we predict that by varying the pH, the g6×6/3b,c pair can be employed to differentially sense Cd 2+ and Hg 2+ cations.

The surface composition of bimetallics can be strongly altered by adsorbing molecules where the metal with the strongest interaction with the adsorbate segregates into the surface. To investigate the effect of reactive gas on the surface composition of Au-Cu alloy, we examined by means of density functional theory to study the segregation behavior of copper in gold matrices. The adsorption mechanisms of CO, NO, and O2 gas molecules on gold, copper, and gold-copper low index (111), (100), and (110) surfaces were analyzed from energetic and electronic points of view. Our results show a strong segregation of Cu toward the (110) surface in the presence of all adsorbed molecules. Interestingly, the Cu segregation toward the (111) and (100) surface could occur only in the presence of CO and at a lower extent in the presence of NO. The analysis of the electronic structure highlights the different binding characters of adsorbates inducing the Cu segregation.

Chitosan-aluminum oxide nanocomposite was synthesized, characterized, and used as a green heterogeneous catalyst to synthesize novel imidazopyrazolylthione derivatives. Nanocomposite polymeric material was characterized by EDS-SEM and XRD. The powerful catalytic activity, and its base character of the nanocomposite, was used to synthesize imidazopyrazolylthione (1) in a good yield compared to traditional cyclocondensation synthesis. Using the nanocomposite catalyst, substitution of the thiol group (1) afforded the corresponding thiourea (2) and the corresponding ester (3). The efficiency of the nanocomposite over the traditional base organic catalyst, Et3N and NaOH, makes it an effective, economic, and reproducible nontoxic catalyst. Moreover, the heterogeneous nanocomposite polymeric film was easily isolated from the reaction medium, and recycled up to four times, without a significant loss of its catalytic activity. The newly synthesized derivatives were screened as antibacterial agents and showed high potency. Molecular docking was also performed for a more in-depth investigation. The results of the docking studies have demonstrated that the docked compounds have strong interaction energies with both Gram-positive and Gram-negative bacteria.

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Enhancing gas sensor efficiency: DFT explores the potential of carbene-functionalized graphene.

In this paper, we used in silico analysis to shed light on the possible interaction between TMPRSS2 and SARS-CoV2 spike (S) protein by examining the role of TMPRSS2 single nucleotide polymorphisms (SNPs) in relation with susceptibility and inter-individual variability of SARS-CoV2 infection. First, we used molecular docking of human TMPRSS2 protein to predict the binding site of TMPRSS2, especially the TMPRSS2 link loops, in order to assess the effect TMPRSS2 SNPs. The latter lead to missense variants on the interaction between TMPRSS2 and SARS-CoV2 S protein. In a second step, we further refine our analysis by performing a structure-function analysis of the complexes using PyMol software, and finally by MD simulations to validate the as-obtained results. Our findings show that 17 SNPs among the 692 natural TMPRSS2 coding variants are in positions to influence the binding of TMPRSS2 with the viral S protein. All of them give more important interaction energy as assessed by docking. Among the 17 SNPs, four missense variants E389A, K392Q, T393S and Q438E lead to "directly increasing" the interaction affinity and 2 missense variants R470I and Y416C cause it "directly decreasing". The R470I and Y416C present in African and American population, respectively. While the other 4 SNP variants (E389A; K392Q; T393S and Q438E) are present only in the European population, which could link the viral infection susceptibility to demographic, geographic and genetic factors.

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