Activated carbon derived from sugarcane and modified with natural zeolite for efficient adsorption of methylene blue dye: experimentally and theoretically approaches.

The introduction of activated carbon/natural zeolite (AC/NZ) as an efficient and reliable nanoadsorbent for enhancing methylene blue (MB) dye adsorption. By calcining sugarcane waste at various temperatures between 500 and 900 °C, activated carbons (ACs) are formed. Both XRD and SEM were used for the characterization of the prepared adsorbents. Adsorption measurements for the removal of MB dye were made on the impact of pH, beginning MB concentration, and contact time. The maximum AC500/NZ adsorption capacity for MB dye at 25 °C, pH 7, and an AC500/NZ mass of 50 mg was found to be approximately 51 mg/g at an initial concentration of 30 ppm. The pseudo-second-order kinetics model and the Temkin isotherm model describe the adsorption process. The Temkin model shows that the adsorption energy is 1.0 kcal/mol, indicating that the MB-to-AC500/NZ adsorption process occurs physically. Our Monte Carlo (MC) simulation studies supported our findings and showed that the Van der Waals dispersion force was responsible for the MB molecule's physical adsorption. The AC500/NZ adsorbent is thought to be a strong contender for water remediation.

Unusual chalcogen⋯chalcogen interactions in like⋯like and unlike YCY⋯YCY complexes (Y = O, S, and Se).

Chalcogen⋯chalcogen interactions were investigated within four types of like⋯like and unlike YCY⋯YCY complexes (where Y = O, S, or Se). A plethora of quantum mechanical calculations, including molecular electrostatic potential (MEP), surface electrostatic potential extrema, point-of-charge (PoC), quantum theory of atoms in molecules (QTAIM), noncovalent interaction (NCI), and symmetry-adapted perturbation theory-based energy decomposition analysis (SAPT-EDA) calculations, were executed. The energetic findings revealed a preferential tendency of the studied chalcogen-bearing molecules to engage in type I, II, III, or IV chalcogen⋯chalcogen interactions. Notably, the selenium-bearing molecules exhibited the most potent ability to favorably participate in all the explored chalcogen⋯chalcogen interactions. Among like⋯like complexes, type IV interactions showed the most favorable negative binding energies, whereas type III interactions exhibited the weakest binding energies. Unexpectedly, oxygen-containing complexes within type IV interactions showed an alien pattern of binding energies that decreased along with an increase in the chalcogen atomic size level. QTAIM analysis provided a solo BCP, via chalcogen⋯chalcogen interactions, with no clues as to any secondary ones. SAPT-EDA outlined the domination of the explored interactions by the dispersion forces and indicated the pivotal shares of the electrostatic forces, except type III σ-hole⋯σ-hole and di-σ-hole interactions. These observations demonstrate in better detail all the types of chalcogen⋯chalcogen interactions, providing persuasive reasons for their more intensive use in versatile fields related to materials science and drug design.

Boron nitride nanoclusters, nanoparticles and nanotubes as a drug carrier for isoniazid anti-tuberculosis drug, computational chemistry approaches.

In this work, the ability of B12N12 fullerene-like nanoclusters as a drug carrier for isoniazid anti-tuberculosis drug has been studied by DFT methods. Binding energies in both gas and water phases are reported. The formed bonds between B12N12-FLN and Iso drug are studied and computed using QMAIM method. NPA is computed to obtain the total charges transferred in the B12N12-FLN-Iso drug complexes, NPA obtained values suggested that the cluster may oxidize the coordinated of Iso drug. The charge-transfer energy values are also computed and confirmed that the charges were transferred from the non-bonding lone-pair (n) of N and O atoms orbitals to the σ* orbitals of B and N atoms of B12N12-FLN. Also, the adsorption of Iso drug on BN nanoparticles surface (different sizes and shapes) and BN nanotubes was studied by Monte Carlo simulation. We found that increasing the BN size did not affect significantly on the adsorption energies of Iso drug for all various BN nanoparticles shapes. All adsorption energies obtained by MC calculations are negative values which revealed that the adsorption of the Iso drug molecule on BN surfaces is exothermic, spontaneous and energetically favourable. Also, the stability of B12N12-FLN-Iso drug complex in water explicitly was studied by MD simulations. MD simulation confirmed that iso-B12N12-FLN complexes are stable in the presence of water molecules. So, finally, we deduced that B12N12 fullerene-like nanoclusters can be acted as a drug carrier for isoniazid anti-tuberculosis drug. Communicated by Ramaswamy H. Sarma.

Effect of External Electric Field on Tetrel Bonding Interactions in (FTF3···FH) Complexes (T = C, Si, Ge, and Sn).

A quantum chemical study was accomplished on the σ-hole interactions of the barely explored group IV elements, for the first time, in the absence and presence of the positively and negatively directed external electric field (EEF). The analyses of molecular electrostatic potential addressed the occurrence of the σ-hole on all the inspected tetrel atoms, confirming their salient versatility to engage in σ-hole interactions. MP2 energetic findings disclosed the occurrence of favorable σ-hole interactions within the tetrel bonding complexes. The tetrel bonding interactions became stronger in the order of C < Si < Ge < Sn for F-T-F3···FH complexes with the largest interaction energy amounting to -19.43 kcal/mol for the optimized F-Sn-F3···FH complex under the influence of +0.020 au EEF. The interaction energy conspicuously evolved by boosting the magnitude of the positively directed EEF value and declining the negatively directed EEF one. The decomposition analysis for the interaction energies was also executed in terms of symmetry-adapted perturbation theory, illuminating the dominant electrostatic contribution to all the studied complexes' interactions except carbon-based interactions controlled by dispersion forces. The outcomes that emerged from the current work reported significantly how the direction and strength of the EEF affect the tetrel-bonding interactions, leading to further improvements in the forthcoming studies of supramolecular chemistry and materials science.

On the Potentiality of X-T-X3 Compounds (T = C, Si, and Ge, and X = F, Cl, and Br) as Tetrel- and Halogen-Bond Donors.

The versatility of the X-T-X3 compounds (where T = C, Si, and Ge, and X = F, Cl, and Br) to participate in tetrel- and halogen-bonding interactions was settled out, at the MP2/aug-cc-pVTZ level of theory, within a series of configurations for (X-T-X3)2 homodimers. The electrostatic potential computations ensured the remarkable ability of the investigated X-T-X3 monomers to participate in σ-hole halogen and tetrel interactions. The energetic findings significantly unveil the favorability of the tetrel···tetrel directional configuration with considerable negative binding energies over tetrel···halogen, type III halogen···halogen, and type II halogen···halogen analogs. Quantum theory of atoms in molecules and noncovalent interaction analyses were accomplished to disclose the nature of the tetrel- and halogen-bonding interactions within designed configurations, giving good correlations between the total electron densities and binding energies. Further insight into the binding energy physical meanings was invoked through using symmetry-adapted perturbation theory-based energy decomposition analysis, featuring the dispersion term as the most prominent force beyond the examined interactions. The theoretical results were supported by versatile crystal structures which were characterized by the same type of interactions. Presumably, the obtained findings would be considered as a solid underpinning for future supramolecular chemistry, materials science, and crystal engineering studies, as well as a fundamental linchpin for a better understanding of the biological activities of chemicals.

Experimentally and theoretically approaches for disperse red 60 dye adsorption on novel quaternary nanocomposites.

A comprehensive study that combined both experimental and computational experiments was performed to evaluate the usage of organo-metal oxide nanocomposite for the elimination of disperse red 60 dye (DR) from aqueous solutions. Chitosan was modified by Schiff base to form nanoneedles chitosan-4-chloroacetophenone derivative. The derivatives were then impregnated with CeO2-CuO-Fe2O3 or CeO2-CuO-Al2O3 metal oxides to prepare a novel quarternary organo-metal oxide nanocomposite. The novel nanocomposite, chitosan-4-chloroacetophenone/CeO2-CuO-Fe2O3 (CF) and chitosan-4-chloroacetophenone/CeO2-CuO-Al2O3 (CA) are cheap and effective nano adsorbents that can be used for the uptake of DR from aqueous solution. The CF and CA nano-composites were characterized using different techniques. Moreover, the effect of adsorption parameters (initial DR concentration, time of contact, pH, temperature, and adsorbent mass) as well as CA and CF reusability tests were performed. Langmuir adsorption isotherm and pseudo-second-order kinetics models were best fitted with the adsorption process. The maximum amount of DR adsorbed was 100 mg/g on CF and CA at pH 2 and 4, respectively with a physical spontaneous, and exothermic adsorption process. Monte Carlo (MC) simulation studies indicated the adsorption of DR molecule on the CF and CA surfaces following a parallel mode in most of all studied configurations, confirming the strong interactions between the DR and surfaces atoms of CF and CA. The molecular structure analysis of DR dye adsorbed on the surface of CF and CA indicated that the adsorption process related to Van der Waals dispersion force. Consequently, this helps to trap DR dye molecules on the surface of CF and CA (i.e., physical adsorption), which supports our experimental results.

Combination and tricombination therapy to destabilize the structural integrity of COVID-19 by some bioactive compounds with antiviral drugs: insights from molecular docking study.

Recently, the SARS-CoV-2 (COVID-19) pandemic virus has been spreading throughout the world. Until now, no certified drugs have been discovered to efficiently inhibit the virus. The scientists are struggling to find new safe bioactive inhibitors of this deadly virus. In this study, we aim to find antagonists that may inhibit the activity of the three major viral targets: SARS-CoV-2 3-chymotrypsin-like protease (6LU7), SARS-CoV-2 spike protein (6VYB), and a host target human angiotensin-converting enzyme 2 (ACE2) receptor (1R42), which is the entry point for the viral encounter, were studied with the prospects of identifying significant drug candidate(s) against COVID-19 infection. Then, the protein stability produced score of less than 0.6 for all residues of all studied receptors. This confirmed that these receptors are extremely stable proteins, so it is very difficult to unstable the stability of these proteins through utilizing individual drugs. Hence, we studied the combination and tricombination therapy between bioactive compounds which have the best binding affinity and some antiviral drugs like chloroquine, hydroxychloroquine, azithromycin, simeprevir, baloxavir, lopinavir, and favipiravir to show the effect of combination and tricombination therapy to disrupt the stability of the three major viral targets that are mentioned previously. Also, ADMET study suggested that most of all studied bioactive compounds are safe and nontoxic compounds. All results confirmed that caulerpin can be utilized as a combination and tricombination therapy along with the studied antiviral drugs for disrupting the stability of the three major viral receptors (6LU7, 6VYB, and 1R42). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11224-020-01723-5.

DFT study of cyclic glycine-alanine dipeptide binding to gold nanoclusters.

In this work, we studied the interactions between cyclic glycine-alanine dipeptide c(GA) and gold nanoclusters (AunNCs, where n = 2-10) using density functional theory (DFT), atoms-in-molecules theory (AIM), and natural bond orbital analysis (NBO). This dipeptide (DP) consists of two amino acid residues (glycine and alanine); thus, the preference of both residues for binding to gold atoms was examined. The preference of alanine residue to the studied AunNCs was found to be greater than that of glycine residue. Two types of interactions were exhibited between the AunNCs and c(GA), the partially-covalent partially-electrostatic type and electrostatic interaction. Performance of two DFT functionals and different basis sets is assessed. The results benchmark the importance of the DFT functional with dispersion and long-range corrections, as well as the polarization functions in the basis sets for the gold lusters-peptide binding. The binding energy (ΔEbind) values of the c(GA)-AunNCs complexes in gas and water implicit solvent were compared with those previously published for cyclic glycine-glycine DP-AunNCs complexes. It was found that the ΔEbind values of the former complexes are greater than those of latter ones in water solvent.

Destabilizing the structural integrity of COVID-19 by caulerpin and its derivatives along with some antiviral drugs: An in silico approaches for a combination therapy.

Presently, the SARS-CoV-2 (COVID-19) pandemic has been spreading throughout the world. Some drugs such as lopinavir, simeprevir, hydroxychloroquine, chloroquine, and amprenavir have been recommended for COVID-19 treatment by some researchers, but these drugs were not effective enough against this virus. This study based on in silico approaches was aimed to increase the anti-COVID-19 activities of these drugs by using caulerpin and its derivatives as an adjunct drug against SARS-CoV-2 receptor proteins: the SARS-CoV-2 main protease and the SARS-CoV-2 spike protein. Caulerpin exhibited antiviral activities against chikungunya virus and herpes simplex virus type 1. Caulerpin and some of its derivatives showed inhibitory activity against Alzheimer's disease. The web server ANCHOR revealed higher protein stability for the two receptors with disordered score (< 0.6). Molecular docking analysis showed that the binding energies of most of the caulerpin derivatives were higher than all the suggested drugs for the two receptors. Also, we deduced that inserting NH2, halogen, and vinyl groups can increase the binding affinity of caulerpin toward 6VYB and 6LU7, while inserting an alkyl group decreases the binding affinity of caulerpin toward 6VYB and 6LU7. So, we can modify the inhibitory effect of caulerpin against 6VYB and 6LU7 by inserting NH2, halogen, and vinyl groups. Based on the protein disordered results, the SARS-CoV-2 main protease and SARS-CoV-2 spike protein domain are highly stable proteins, so it is quite difficult to unstabilize their integrity by using individual drugs. Also, molecular dynamics (MD) simulation indicates that binding of the combination therapy of simeprevir and the candidate studied compounds to the receptors was stable and had no major effect on the flexibility of the protein throughout the simulations and provided a suitable basis for our study. So, this study suggested that caulerpin and its derivatives could be used as a combination therapy along with lopinavir, simeprevir, hydroxychloroquine, chloroquine, and amprenavir for disrupting the stability of SARS-CoV2 receptor proteins to increase the antiviral activity of these drugs.