Π-electron Research Articles

Sensing of Pb (II) ion by micro and nanocarbon materials- influence of functionality and pi-electron density

In the aspect of pollution due to heavy metal ions, especially Pb (II) ions, there is an urgent need for simple, effective materials and processes for sensing the ions. The present study approaches the sensing of Pb (II) ions by non-metal (O, N and S) doped micro and nanoscale Carbon materials. The unique emission (Fluorescence) properties of the as-prepared doped samples of graphene oxides and Carbon Microspheres were tapped in the selective sensing process of nanomolar to the micromolar concentration of Pb (II) ions. The role-play of Carbon dimensionality, functionality and sp2 Carbon density (pi electron density) in the sensing mechanism was evaluated. The study provided an overview of fundamental aspects of heavy metal ion sensing by Carbon-based nanomaterials (CBNs).

Thiadiazole-thiazole derivatives as potent anti-tubercular agents: Synthesis, biological evaluation, and In silico docking studies

The present study focuses on research findings related to the development and assessment of thiadiazole-linked thiazole derivatives as promising anti-tubercular agents. We present the synthesis data of eleven new compounds (4a-4k) and confirm their structures using spectroscopic techniques. Subsequently, the compounds were screened for their anti-tuberculosis activities against M. tuberculosis H37Ra. The results demonstrated that compounds 3 and 4b exhibited minimum inhibitory concentration (MIC) of 3.90 μg/mL and 7.81 μg/mL, respectively. In-vitro, studies for few compounds exhibited high antioxidant activity against DPPH and OH radical scavengers along with minimal to no cytotoxicity against RBCs which is a promising result. Investigation of molecular docked conformations revealed different molecular interactions such as hydrogen bonds, halogen bonds, and interactions involving Pi electron cloud. The study sheds light on conserved interactions with residues like Met131, Val163, His90 and Gln161 from the tubercular MCAT enzyme. Interestingly, the synthetic chemistry reveals that the employment of tetra-n-butylammonium bromide (TBAB) plays a crucial role for N-butylation and it also expedites the reaction in tetrahydrofuran solvent.

Imidazo[1,2-a]pyridine and Imidazo[1,5-a]pyridine: Electron Donor Groups in the Design of D-π-A Dyes.

This work investigates the electron-donating capabilities of two 10-π electron nitrogen bridgehead bicyclic [5,6]-fused ring systems, imidazo[1,2-a]pyridine and imidazo[1,5-a]pyridine rings. Eight compounds with varying positions of electron-withdrawing moieties (TCF or DCI) coupled to the imidazopyridine ring were synthesized and studied. DCI-containing compounds (Ib-IVb) exhibited a purely dipolar nature with broad absorption bands, weak fluorescence, large Stokes shifts, and strong solvatochromism. In contrast, TCF-containing compounds (Ia-IVa) demonstrated diverse properties. Imidazo[1,2-a]pyridine derivatives Ia and IIa were purely dipolar, while imidazo[1,5-a]pyridine derivatives IIIa and IVa displayed a cyanine-like character with intense absorption and higher quantum yields of emission. The observed gradual red shift in optical properties with changing electron-donor groups (IIb < Ib < IIIb < IVb) and (IIa < Ia < IIIa < IVa) underscores the stronger electron-donor character of imidazo[1,5-a]pyridine compared to that of imidazo[1,2-a]pyridine. Furthermore, crystalline powders of imidazo[1,2-a]pyridine derivatives exhibited fluorescence despite minimal emission in solution. Two compounds (Ib and IVa) were successfully formulated into nanoparticles for potential in vivo imaging applications in zebrafish embryos.

Synthesis of Aryl‐Functionalized Benzo[d,e]Benzo[4,5]İmidazo[2,1‐a]Isoquinolin‐7‐One Derivatives: DNA Intercalation Causing Cytotoxicity

AbstractThis study focuses on the cytotoxic effect properties of 4‐aryl‐functionalized benzo[d,e]benzo[4,5]imidazo[2,1‐a]isoquinolin‐7‐one (4‐X−Ar−BBI). The electron‐withdrawing and electron‐donating substituents located at the para position of the phenyl ring attached to the heterocyclic structure have altered the pi electron density within the structure. This change in electron density has influenced the intercalation ability of the heterocyclic structure and has impacted the intensity of its interaction with DNA. The 4‐aryl‐benzo[d,e]benzo[4,5]imidazo[2,1‐a]isoquinolin‐7‐one derivatives (4‐X−Ar−BBI) were prepared via the Suzuki–Miyaura cross‐coupling reaction. The optimum reaction conditions were determined to be 70 °C for 5 hours using catalyst 1 and K2CO3, resulting in a yield of 96 % of 4‐H−Ar−BBI. Characterization of all compounds (4‐X−Ar−BBI) was performed using Fourier Transform Infrared spectroscopy, mass spectrometry, and 1H‐ and 19F‐NMR spectroscopies. The cytotoxic activities of the compounds (4‐X−Ar−BBI) were investigated against cancer cell lines, specifically HeLa (human cervix adenocarcinoma epithelial), PC3 (human prostate), and MCF‐7 (human breast). The stability of 4‐CN−Ar−BBI and the binding modes between 4‐CN−Ar−BBI and DNA were investigated via 1H‐NMR spectroscopy and UV‐Vis spectroscopy, respectively. 4‐CH3−3‐NO2−Ar−BBI exhibited the most potent cytotoxic activity against MCF‐7, and 4‐F−Ar−BBI showed the highest activity against HeLa, with IC50 values of 3.675 and 7.370 μM, respectively.

Synthesis, Biological and Molecular Docking Studies of Thiazole-Thiadiazole derivatives as potential Anti-Tuberculosis Agents.

Tuberculosis remains a global health threat, with increasing infection rates and mortality despite existing anti-TB drugs. The present work focuses on the research findings regarding the development and evaluation of thiadiazole-linked thiazole derivatives as potential anti-tuberculosis agents. We present the synthesis data and confirm the compound structures using spectroscopic techniques. The current study reports twelve thiazole-thiadiazole compounds (5 a-5 l) for their anti-tuberculosis and related bioactivities. This paper emphasizes compounds 5 g, 5 i, and 5 l, which exhibited promising MIC values, leading to further in silico and interaction analysis. Pharmacophore mapping data included in the present analysis identified tubercular ThyX as potential drug targets. The compounds were evaluated for anti-tubercular activity using standard methods, revealing significant MIC values, particularly compound 5 l, with the best MIC value of 7.1285 μg/ml. Compounds 5 g and 5 i also demonstrated moderate to good MIC values against M. tuberculosis (H37Ra). Structural inspection of the docked poses revealed interactions such as hydrogen bonds, halogen bonds, and interactions containing Pi electron cloud, shedding light on conserved interactions with residues like Arg 95, Cys 43, His 69, and Arg 87 from the tubercular ThyX enzyme.

Conductive Gels for Energy Storage, Conversion, and Generation: Materials Design Strategies, Properties, and Applications.

Gel-based materials have garnered significant interest in recent years, primarily due to their remarkable structural flexibility, ease of modulation, and cost-effective synthesis methodologies. Specifically, polymer-based conductive gels, characterized by their unique conjugated structures incorporating both localized sigma and pi bonds, have emerged as materials of choice for a wide range of applications. These gels demonstrate an exceptional integration of solid and liquid phases within a three-dimensional matrix, further enhanced by the incorporation of conductive nanofillers. This unique composition endows them with a versatility that finds application across a diverse array of fields, including wearable energy devices, health monitoring systems, robotics, and devices designed for interactive human-body integration. The multifunctional nature of gel materials is evidenced by their inherent stretchability, self-healing capabilities, and conductivity (both ionic and electrical), alongside their multidimensional properties. However, the integration of these multidimensional properties into a single gel material, tailored to meet specific mechanical and chemical requirements across various applications, presents a significant challenge. This review aims to shed light on the current advancements in gel materials, with a particular focus on their application in various devices. Additionally, it critically assesses the limitations inherent in current material design strategies and proposes potential avenues for future research, particularly in the realm of conductive gels for energy applications.

Sustainable carbon quantum dots enhanced photoluminescence for bioimaging applications: An in vitro and in silico analysis

This study explores the synthesis and characterization of glucose-based carbon quantum dots (CQDs) for potential applications in the field of photoluminescence. The unique properties of CQDs are investigated, highlighting their distinct features compared to traditional carbon dots. Here, commercially available L-glucose is a precursor that has been chosen as the starting material to produce fluorescent carbon quantum dots (CQDs). The low to high quantum yield CQDs were reduced by chemical reduction method using sodium borohydride and then thiol (L-cysteine) induced for the stabilizer to stabilize rigidified reduced CQDs-L-cysteine (r-CQDs-Cys). The effect of pH and the ligand effect have been investigated for the photoluminescence (PL) studies of r-CQDs-Cys, yielding emission responses that were tuned according to the pH and ligand. The optimized CQDs to r-CQDs-Cys shows the quantum yield (QY) increased from 8.56 % to 42.72 %. The fluorescent QY of the synthesized CQDs investigated for the cytotoxicity test explicates that 90 % of the cells (MCF7) maintain their normal morphology even at higher concentrations of r-CQDs-Cys at 100 µg/mL. This Cytotoxicity test suggests that r-CQDs-Cys are non-toxic biocompatible and the binding energy value −6.8 kcal/mol of the carbon quantum dots was confirmed by in-silico studies. A total of 13 hydrogen bonds, 2 carbon bonds, and one Pi bond were formed during the interaction of the MCF7 cancer cell line with carbon quantum dots. The overall results confirmed that r-CQDs-Cys enhanced QY, fluorescence emission, and superior water solubility of the while compared to others which made them suitable for bio-imaging applications.

Degradation Mechanism of Aflatoxin M1 by Recombinant Catalase from Bacillus pumilusE-1-1-1: Food Applications in Milk and Beer.

A bacteria capable of degrading aflatoxin M1 (AFM1) was isolated from African elephant manure. It was identified as Bacillus pumilus by 16s rDNA sequencing and named B. pumilusE-1-1-1. Compared with physical and chemical methods, biological methods have attracted much attention due to their advantages, such as thorough detoxification, high specificity, and environmental friendliness. This work aimed to study the effects of a recombinant catalase (rCAT) from B. pumilusE-1-1-1 on the degradation of AFM1 in pattern solution. The degradation mechanism was further explored and applied to milk and beer. Kinetic Momentum and Virtual Machine Maximum values for rCAT toward AFM1 were 4.1 μg/mL and 2.5 μg/mL/min, respectively. The rCAT-mediated AFM1 degradation product was identified as C15H14O3. Molecular docking simulations suggested that hydrogen and pi bonds played major roles in the steadiness of AFM1-rCAT. In other work, compared with identical density of AFM1, survival rates of Hep-G2 cells incubated with catalase-produced AFM1 degradation products increased by about 3 times. In addition, degradation rates in lager beer and milk were 31.3% and 47.2%, respectively. Therefore, CAT may be a prospective substitute to decrease AFM1 contamination in pattern solution, milk, and beer, thereby minimizing its influence on human health.

Structure, Antioxidant Activity and Antimicrobial Study of Light Lanthanide Complexes with p-Coumaric Acid.

This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2). Structural studies were conducted via spectroscopic methods (FTIR, ATR, UV). Thermal degradation studies of the complexes were performed. The results are presented in the form of TG, DTG and DSC curves. Antioxidant properties were determined via activity tests against DPPH, ABTS and OH radicals. The reducing ability was tested via CUPRAC assays. Minimum inhibitory concentrations (MICs) of the ligand and lanthanide complexes were determined on E. coli, B. subtilis and C. albicans microorganisms. The antimicrobial activity was also determined using the MTT assay. The results were presented as the relative cell viability of C. albicans, P. aeruginosa, E. coli and S. aureus compared to controls and expressed as percentages. In the obtained complexes in the solid phase, lanthanide ions coordinate three ligands in a bidentate chelating coordination mode through the carboxyl group of the acid. Spectroscopic analysis showed that lanthanide ions increase the aromaticity of the pi electron system of the ligand. Thermal analysis showed that the complexes are hydrated and have a higher thermal stability than the ligand. The products of thermal decomposition of the complexes are lanthanide oxides. In the aqueous phase, the metal combines with the ligand in a 1:1 molar ratio. Antioxidant activity tests showed that the complexes have a similar ability to remove free radicals. ABTS and DPPH tests showed that the complexes have twice the ability to neutralise radicals than the ligand, and a much higher ability to remove the hydroxyl radical. The abilities of the complexes and the free ligand to reduce Cu2+ ions in the CUPRAC test are at a similar level. Lanthanide complexes of p-coumaric acid are characterised by a higher antimicrobial capacity than the free ligand against Escherichia coli bacteria, Bacillus subtilis and Candida albicans fungi.

Cananga oil inhibits Salmonella infection by mediating the homeostasis of purine metabolism and the TCA cycle

Ethnopharmacology relevanceCananga oil (CO) is derived from the flowers of the traditional medicinal plant, the ylang-ylang tree. As a traditional antidepressant, CO is commonly utilized in the treatment of various mental disorders including depression, anxiety, and autism. It is also recognized as an efficient antibacterial insecticide, and has been traditionally utilized to combat malaria and acute inflammatory responses resulting from bacterial infections both in vitro and in vivo. Aim of the studyThe objective of this study is to comprehensively investigate the anti-Salmonella activity and mechanism of CO both in vitro and in vivo, with the expectation of providing feasible strategies for exploring new antimicrobial strategies and developing novel drugs. MethodsThe in vitro antibacterial activity of CO was comprehensively analyzed by measuring MIC, MBC, growth curve, time-killing curve, surface motility, biofilm, and Live/dead bacterial staining. The analysis of the chemistry and active ingredients of CO was conducted using GC-MS. To examine the influence of CO on the membrane homeostasis of Salmonella, we conducted utilizing diverse techniques, including ANS, PI, NPN, ONPG, BCECF-AM, DiSC3(5), and scanning electron microscopy (SEM) analysis. In addition, the antibacterial mechanism of CO was analyzed and validated through metabolomics analysis. Finally, a mouse infection model of Salmonella typhimurium was established to evaluate the toxic side effects and therapeutic effects of CO. ResultsThe antibacterial effect of CO is the result of the combined action of the main chemical components within its six (palmitic acid, α-linolenic acid, stearic acid, benzyl benzoate, benzyl acetate, and myristic acid). Furthermore, CO disrupts the balance of purine metabolism and the tricarboxylic acid cycle (TCA cycle) in Salmonella, interfering with redox processes. This leads to energy metabolic disorders and oxidative stress damage within the bacteria, resulting in bacterial shock, enhanced membrane damage, and ultimately bacterial death. It is worth emphasizing that CO exerts an effective protective influence on Salmonella infection in vivo within a non-toxic concentration range. ConclusionThe outcomes indicate that CO displays remarkable anti-Salmonella activity both in vitro and in vivo. It triggers bacterial death by disrupting the balance of purine metabolism and the TCA cycle, interfering with the redox process, making it a promising anti-Salmonella medication.

Application of a Novel Symmetric Benzophenone Derivative Schiff Base in Lyotropic Media and Spectroscopic Properties

The structural and spectroscopic properties of a new -ONNO- type Schiff base were analyzed. The compound 6,6'-((1E,1'E)-(hexane-1,6-diylbis(azaneylylidene))bis(phenylmethaneylylidene))bis(3-(octyloxy)phenol) was synthesized by condensing a diamine and a ketone in tetrahydrofuran, resulting in a high yield. The symmetric Schiff base, in which both amine ends converted to the imine structure, was examined using XRD, NMR, IR and UV-vis. spectroscopies. The theoretical calculations were done successfully using DFT approach at 6-31G(d, p) basis set to investigate the properties of the title compound that cannot be studied by experimental analyses. NBO analysis was used to study hyper-conjugative interactions involving the overlap of sigma (σ) or pi (π) electrons and electron density between adjacent atoms and to determine the stabilization energy. The DFT theoretical parameters and XRD experimental parameters were compared and showed good agreement. 2D fingerprint and 3D Hirshfeld surface plots were obtained to determine the intermolecular interactions. The features of the optimized structure were investigated by several analyses such: NBO, Frontier molecular orbitals, ESP, MEP and ECT which cannot be studied by theoretical methods. The UV-vis. spectroscopy was used to investigate the interaction of the synthesized benzophenone Schiff base compound with lyotropic media. The synthesized compound is significantly compatible with the prepared lyotropic medium due to its highly symmetrical and amphiphilic structure.

New insight into the role of the self-assembly of heteroatom compounds in heavy oil viscosity enhancement.

Unveiling the role of heteroatom compounds in heavy oil viscosity is pivotal for finding targeted viscosity reduction methods to improve oil recovery. This research investigates the impact of heteroatoms in asphaltene molecules by utilizing quantum chemical calculations and molecular dynamics simulations to analyze their electrostatic potential characteristics, pairwise interactions, and dynamic behavior within realistic reservoirs. Heteroatom compounds can influence the molecular-level properties of asphaltenes and thus impact the macroscopic behavior of heavy oils. Research results suggest that the presence of ketone and aromatic rings in asphaltene molecules leads to the unrestricted movement of pi electrons due to their collective electronegativity. Two distinct configurations of asphaltene dimers, face-to-face, and edge-to-face, were observed. Intermolecular interactions were predominantly governed by van der Waals forces, highlighting their significant role in stabilizing asphaltene aggregates. The distribution of asphaltene molecules in the oil phase can be summarized as the "rebar-cement" theory. In the heteroatom-free system, the face-to-face peaks in the radial distribution function exhibit significantly reduced magnitudes compared to those in the heteroatom-containing system. This emphasizes the pivotal function of heteroatoms in connecting molecular components to form a more compact asphaltene structure, which may result in a higher viscosity of heavy oil. These findings give insight into the significance of heteroatoms in bridging molecular components and shaping the intricate structure of asphaltene and advance our understanding of heavy oil viscosity properties.

A Review on Thiazole derivatives and their impact as hypoglycemic agents in drug developments

The impact of thiazole derivatives as a hypoglycemic agent has been noted for many decades. Thiazole is heterocyclic containing sulphur and nitrogen as heteroatom whereas the free pi (π) electrons can move from one bond to another freely to have aromatic properties. Due to these aromatic properties, various reactions are possible with these rings due to the various donor-acceptor position. Thiazole can regulate various physiochemical processes within the body. Due to this, it has been reported for various biological activities such as antimicrobial, antitumor, antidiabetic, antioxidant, anti-inflammatory etc. However, there are various drugs containing thiazole are rosiglitazone, pioglitazone, and troglitazone have shown their effectiveness in controlling elevated blood sugar. In this regard, the present review explains the different thiazole derivatives synthesized and their impact as hypoglycemic agents.

Design, synthesis, docking study, cytotoxicity evaluation, and PI3K inhibitory activity of Novel di-thiazoles, and bis(di-thiazoles)

A series of novel thiazole hybrids were designed and synthesized using a molecular hybridization approach to develop more potent Pi3k inhibitors for cancer treatment. As a result of the reaction of (phenylthiazol-5-yl)ethylidenehydrazine-1-carbothioamide with the corresponding bis-bromoacetyl derivatives, reasonable yields of novel bis-dithiazoles linked via aliphatic, aromatic, or heterocyclic cores were obtained. The structural details of the new compounds were confirmed using spectral data and elemental analysis. All of the proposed compounds were molecularly docked based on their structural similarity to the alpelisib pi3k inhibitor, and compounds 11e and 11d demonstrated very good binding modes that ranged between hydrogen and pi bonds. All compounds were tested for anticancer activity against HT29 colon cancer cells. The IC50 values for compounds 11d and 11e were 4.4 and 8.3 nM, respectively. In addition, PI3K enzyme inhibition activity was assessed, and the results ranged from very low IC50 for 11e and 11d, which revealed 2.33 and 2.55 nM, to moderate for 11b, 11c, 13b, and 15b, with IC50 of 7.58, 6.15, 7.9, and 9.11 nM, respectively, when compared to alpelisib, which revealed an IC50 of 4.96 nM. The inhibitory activity of the most potent compounds was qualitatively evaluated by Western Blotting, and pi3k gene expression was found to be inhibited to half of its maximum value.

STUDY MOLECULES DOCKING OF ALKALOIDS IN KRATOM ON SEROTONIN TRANSPORTER (SERT), NOREPINEPHRINE TRANSPORTER (NET), AND MONOAMINE OXIDASE (MAO)

Kratom (Mitragyna speciosa Korth) is a tropical plant originating from Southeast Asia that predominantly contains alkaloid compounds and can potentially maintain levels of monoamine compounds in the body to treat depression. The study aimed to examine the potential of 8 alkaloid compounds in kratom as antidepressants towards four target proteins: Serotonin Transporter (SERT), Dopamine Transporter (DOPAT), Leucine Transporter (LEUT), and Monoamine Oxidase (MAO) via molecular docking. The Pyrx program is used with exhaustiveness 106 as the protocol, and the grid is adapted to the active site of each receptor. The affinity values ​​of the alkaloid compounds in kratom are mitragynine, 7-hydroxy mitragynine, speciociliatine, paynantheine, speciogynine, corynantheidine, mitraciliatine, and 9-hydroxycorynantheidine, for MAO were -7.1, -6.1, -5.7, -6.7, -5.7, -7.7, -5.7, and -5.7 kcal/ mole. All compounds bind to amino acid residues in the target protein through hydrogen and pi (π) bonds. All the tested alkaloid compounds have the potential to be re-uptake inhibitors SERT, DOPAT, LEUT, and Monoamine Oxidase (MAO).

The on-Surface Supramolecular Chemistry of Porphyrins, Phthalocyanines and Sub-Phthalocyanines: How Shape and Functionalization Change the Game

By their role in biochemistry, porphyrins have played a central role for “Chemistry beyond the molecule”, long before the term ‘supramolecular chemistry’ has been coined. It is interesting that the bio-chemical functions of porphyrins predominantly derive from the center metal atom, its coordination shell and the coordination-site specific properties. The integration of porphyrins into bio-molecules is safeguarded by covalent chemistry and not ‘supra-molecular’ as such. Nevertheless, square planar porphyrins and pthalocyanines take a decisive role in the development of on-surface supra molecular chemistry: This for their excellent stability and for the many ways they can be functionalized with ligands. Thereby, porphyrin and phthalocyanine chemistry paved the way towards the systematic investigation of many different functional groups known to direct self-assembly and their influence on the formation of on-surface supramolecular layers and chains. I will review the results of on-surface supramolecular assembly experiments performed at the solid-vacuum interface with CN-[1], CN-phenyl, alkoxy [1], fluoro [2] and fluorophenyl [3] and di-methylene-aniline derived functional groups and discuss the supramolecular ordering in terms of estimated binding energies and formation kinetics. It is also interesting to compare the supramolecular ordering in fluids with the constrained ordering of molecules confined to surface substrates. Further insight into the directing power of the individual functional groups derives from a fresh look at the three-fold symmetric pyramidal sub-Phthalocyanines.Fig. 1) Supramolecular ordering of substituted porphyrins in networks fromed by CN-phenyl interaction: a) and b) show higher magnification micrographs of c) and d) in two different imaging modes emphasizing the pi orbitals (HOMO) and the alkyl substituants, respectively. e) shows the dynamicity of a network from sterically more demanding alkyl-phenyl substituents. (for further details see [1] and references therein)[1] N. Wintjes et al. J. Am. Chem. Soc. 2010, 132, 7306–7311[2] J. Girovsky et al. Nature Communications 2017 8:15388[3] S. Nowakowska et al. ACS Nano 2018, 12, 768−778. Figure 1

Effects of strong electric field and solvation on the excitation process of mineral oil molecules

Studying the excitation process of mineral oil molecules under the influence of electric fields and different environments is crucial for understanding the development of insulating oil streamer discharge at the atomic scale. In this paper, based on density functional theory, quantitative characteristic descriptors, hole-electron distribution, and transition density matrix (TDM) analysis, the excitation energies of the first five excited states are used to analyse the excitation process of mineral oil molecules under various conditions. The results obtained under four different electric field strengths (0, 0.0001 a.u., 0.001 a.u. and 0.01 a.u.) and three different environments (vacuum, mineral oil, and natural ester) are compared. The results show that for electric field strengths ranging from 0 to 0.001 a.u., the excitation types of the three mineral oil molecules are localized excitations. However, when the electric field intensity reaches 0.01 a.u., the excitation type of mineral oil molecules changes to charge transfer excitation due to the strong electric field. There are significant differences in the positions of holes and electrons in the excitation processes of the mineral oil molecules under different conditions. While the excitation process of chain hydrocarbon molecules under vacuum and in solution exhibits some differences, the excitation processes of dicycloalkanes and aromatic hydrocarbons are not affected by environmental factors. The electronic transitions in the excitation process of chain hydrocarbons and dicycloalkanes are sigma->sigma* transition processes, whereas in aromatic hydrocarbons, it is primarily pi->pi* transition processes. Compared to pi orbitals, sigma orbitals are lower energy empty orbitals, and sigma* orbitals are higher energy empty orbitals. As a result, the excitation energies of the chain hydrocarbons and dicycloalkanes are higher than that of aromatic hydrocarbons. Furthermore, a strong electric field changes the excitation type of mineral oil molecules, accompanied by a significant decrease in their excitation energy. The selection of insulating oil molecules, whose excitation process is sigma->sigma* or modifying the transition mode of electrons in the excitation process through doping and modification, is an important approach to improve the excitation energy of insulating oil. The findings of this research have the potential to enhance our understanding of the microscopic mechanisms that influence the development of streamer discharge in liquid insulating materials.

Ambient temperature NO2 removal by adsorption on transition metal ion-exchanged chabazite zeolites

NO2 as a toxic air pollutant causes serious health problems and contributes to environmental damages, which needs to be abated to a harmless level urgently. However, the abatement of low-concentration NO2 pollution under ambient temperature is challenging due to the ineffectiveness of the state-of-the-art deNOx technologies which are only efficient at elevated temperatures (>300 °C). Adsorption is herein studied as an alternative approach for ambient temperature NO2 removal, using transition metal (i.e., Ag+, Cu2+, Co2+, Ni2+, Zn2+, In3+, and Ce3+) ion-exchanged chabazite (CHA) zeolites with different Si/Al ratios (Si/Al = 2, 6, and 12). NO2 is dominantly physiosorbed on the as-prepared samples, which enables the reversible adsorption in cyclic adsorption process. Ni2+ and Co2+ as active adsorption sites showed elevated affinity to NO2 molecules, which was attributed to the formation of Pi-back bonding via the donation of the electrons in dz2 orbital of the metal ions to Pi × orbitals of NO2 molecule, as evidenced by the changes in the electron occupancies in the orbitals of both transition metal ions and NO2 molecule upon NO2 adsorption (DFT calculation). Co2+ ion-exchanged CHA with Si/Al ratio of 2 (Co2+-2-L) showed an outstanding NO2 capacity of 4.65 mmol/g, with a stable NO2 removal performance verified by the adsorption-desorption cycles. The NO release amount of our adsorbents (<14%) was lower than other reported materials and can be further reduced by our designed double-bed adsorber. This study provides new fundamental knowledge in developing zeolite-based Pi-back bonding adsorbents for NO2 removal, which not only is of timely significance for developing sought-after technologies for NO2 abatement, but also provides a model adsorbent for the adsorptive removal of other molecules with Pi bonds (e.g., CO, NO, etc.)

Investigating valley-dependent current generation due to asymmetric energy dispersion for charge-transfer from a quantum dot to single-walled carbon nanotube

Single-wall carbon nanotubes (SWCNT), which consist of a two-dimensional hexagonal lattice of carbon atoms, possess unique mechanical, electrical, optical and thermal properties. SWCNT can be synthesized in diverse chiral indexes to determine certain attributes. This work theoretically investigates electron transport in different directions along SWCNT. The electron studied in this research transfers from the quantum dot that can possibly move to the right or left direction in SWCNT with different valley-dependent probability. These results show that valley polarized current is present. The valley current in the right and left directions has a composition of valley degrees of freedom where its components (K and K′) are not identical. Such a result can be traced theoretically by certain effects. That firstly is the curvature effect on SWCNT in which the hopping integral between pi electrons from the flat graphene is altered, and another is curvature-inducing sigma -pi mixture. Due to these effects, the band structure of SWCNT is asymmetric in certain chiral indexes leading to the asymmetry of valley electron transport. Our results exhibit that the zigzag chiral indexes is the only type making electron transport symmetrical that is different to the result from the other chiral index types which are the armchair and chiral. This work also illustrates the characteristic of the electron wave function propagating from the initial point to the tip of the tube over time, and the current density of the probability in specific times. Additionally, our research simulates the result from the dipole interaction between the electron in QD and the tube that impacts the lifetime of the electron being in QD. The simulation portrays that more dipole interaction encourages the electron transfer to the tube, thereby shortening the lifetime. We as well suggest the reversed electron transfer from the tube to QD that the time duration of such transfer is much less than the opposite transfer owing to the different orbital of the electron’s states. Valley polarized current in SWCNTs may also be used in the development of energy storage devices such as batteries and supercapacitors. The performance and effectiveness of nanoscale devices, including transistors, solar cells, artificial antennas, quantum computers, and nano electronic circuits, must be improved in order to achieve a variety of benefits.

2-Guanidinobenzazoles as Building Blocks to Afford Biologically Active Derivatives

Abstract: 1,3-Benzazoles (BZs) are interesting compounds in medicinal chemistry. For instance, compounds with the BZ nucleus exhibit diverse biological activities and some of them are broadly utilized in clinical applications. In this sense, medicinal chemists aim at the development of new procedures to synthesize these kinds of molecules. The 2-aminobenzimidazole 2ABI derivatives, such as Enviradine (antiviral), Astemizole (antihistaminic), and Albendazole (antimicrobial), which contain the intra-cyclic guanidine nucleus, are used in medicinal chemistry. The guanidine group, considered a super base, when bonded to a benzazole ring, results in the 2-guanidinobenzazoles (2GBZs), modifying the biological activity of these heterocycles. The structure of 2GBZs is of significance as the 10-π electron system of the aromatic benzazole ring is conjugated with the exocyclic guanidine group to acquire a planar delocalized structure. This class of molecules has at least four nitrogen atoms with free lone pairs and four labile hydrogen atoms, resulting in these compounds having amphoteric character. On the other hand, synthetic chemists have used 2GBZs as a building block to produce derivatives as medicinally important molecules. On these bases, in this work, we prepared a bibliographic review of the methodologies reported in the literature used in the synthesis of 2GBZ derivatives of pharmacological interest. We focused the investigation on 2-guanidinebenzoxazol (2GBO), 2-guanidinebenzothiazol (2GBT) and 2-guanidinebenzimidazole (2GBI) as building blocks. We found that compounds derivatives were N-substituted-2GBZs, 2-(pyrimidyl)-ABZs and 1,3,5-triazino[1,2-a]-BZs, which are described chronologically. This work will help searchers related to bioorganic chemistry, inorganic chemistry, medicinal chemistry and pharmaceutical industry in the recent methodologies to synthetize 2-guanidinobenzazole derivatives to be proposed as materials in the different areas. This topic will provide information on the utility for medicinal chemists dedicated to the design and synthesis of this class of compounds to be tested with respect to their biological activities and be proposed as new pharmacophores.