Heteroatom Research Articles

Charge injection dynamics in oxygen-functionalized and heteroatom-doped reduced graphene oxide and their impact on supercapacitor performance: An experimental and DFT investigation

To elucidate the synergistic effects of oxygen functional groups (OFGs) and heteroatoms (HAs) on charge injection dynamics and the electrochemical performance of reduced graphene oxide (rGO), a combination of experimental techniques and density functional theory (DFT) analyses were employed. GO was synthesized using a modified Hummers method and the sample reduced hydrothermally at 150 °C demonstrated the highest areal capacitance of 817 mF/cm2. To understand the diffusion and charge transfer characteristics, the diffusion coefficient and distribution of relaxation time studied using the Electrochemical Impedance Spectroscopy data. Further the X-ray photoelectron spectroscopy (XPS) confirmed the incorporation of OFGs and HAs in the rGO. A partially oxygen-functionalized, nitrogen, and sulfur-doped graphene (NS-POG) model was constructed based on the XPS data and analyzed using DFT. The projected density of states analysis revealed a Fermi level shift, indicating the introduction of excess electrons due to incorporating OFGs and HAs in graphene, thereby improving the charge carrier concentration in the partially reduced or oxidized systems. The NS-POG system exhibited a quantum capacitance of 85.92 μF/cm2. Additionally, potassium ion (K+) adsorption studies indicated that the adsorption energy was highest near sulfur atoms, suggesting that electrolyte ions exhibit enhanced electrochemical activity in proximity to sulfur. These findings provide insight into the mechanisms by which OFGs and HAs enhance the performance of rGO and highlighting the potential of NS-rGO in supercapacitor applications.

Nitrogen and Sulfur Doped Porous Carbon Sheet with Trace Amount of Iron as Efficient Polysulfide Conversion Catalyst for High Loading Lithium-Sulfur Batteries.

The major challenges in enhancing the cycle life of lithium-sulfur (Li-S) batteries are the polysulfide (PS) shuttling and sluggish reaction kinetics (S to Li2S, Li2S to S). To alleviate the above issues use of hetero atom doped carbon as cathode host matrix is a low-cost and efficient approach as it works as a dual-functional framework for PS anchoring as well as electrocatalyst for faster redox kinetics. Here, the dual role of the Fe-containing heteroatom-doped carbon sheets (CS) in chemisorption of Li2S6 and catalyzing its faster conversion to Li2S is established through UV-Vis, XPS and CV studies. To substantiate the catalytic effect composite cathodes were prepared by encapsulating sulfur in CS which is further blended with carbon nanotubes (CNTs) to form free-standing cathode. The electrochemical performance of the three cathodes viz., S@Fe-N-CS-CNT, S@Fe-S-CS-CNT and S@Fe-NS-CS-CNT were evaluated by constructing Li-S cells. Among all, the S@Fe-NS-CS-CNT delivers a high initial discharge capacity of 1017 mAh g-1 at 0.5 C rate and sustains 751 mAh g-1 capacity after 260 cycles with a capacity retention of 73.8 %. Even at high S-loading (12 mg cm-2), it delivers an initial discharge capacity of 892 mAh g-1 and it retained 575 mAh g-1 after 200 cycles.

Evaluation of Alpha-Synuclein and Tau Antiaggregation Activity of Urea and Thiourea-Based Small Molecules for Neurodegenerative Disease Therapeutics.

Alzheimer's disease (AD) and Parkinson's disease (PD) are multifactorial, chronic diseases involving neurodegeneration. According to recent studies, it is hypothesized that the intraneuronal and postsynaptic accumulation of misfolded proteins such as α-synuclein (α-syn) and tau, responsible for Lewy bodies (LB) and tangles, respectively, disrupts neuron functions. Considering the co-occurrence of α-syn and tau inclusions in the brains of patients afflicted with subtypes of dementia and LB disorders, the discovery and development of small molecules for the inhibition of α-syn and tau aggregation can be a potentially effective strategy to delay neurodegeneration. Urea is a chaotropic agent that alters protein solubilization and hydrophobic interactions and inhibits protein aggregation and precipitation. The presence of three hetero atoms (O/S and N) in proximity can coordinate with neutral, mono, or dianionic groups to form stable complexes in the biological system. Therefore, in this study, we evaluated urea and thiourea linkers with various substitutions on either side of the carbamide or thiocarbamide functionality to compare the aggregation inhibition of α-syn and tau. A thioflavin-T (ThT) fluorescence assay was used to evaluate the level of fibril formation and monitor the anti-aggregation effect of the different compounds. We opted for transmission electron microscopy (TEM) as a direct means to confirm the anti-fibrillar effect. The oligomer formation was monitored via the photoinduced cross-linking of unmodified proteins (PICUP). The anti-inclusion and anti-seeding activities of the best compounds were evaluated using M17D intracellular inclusion and biosensor cell-based assays, respectively. Disaggregation experiments were performed with amyloid plaques extracted from AD brains. The analogues with indole, benzothiazole, or N,N-dimethylphenyl on one side with halo-substituted aromatic moieties had shown less than 15% cutoff fluorescence obtained with the ThT assay. Our lead molecules 6T and 14T reduced α-syn oligomerization dose-dependently based on the PICUP assays but failed at inhibiting tau oligomer formation. The anti-inclusion effect of our lead compounds was confirmed using the M17D neuroblastoma cell model. Compounds 6T and 14T exhibited an anti-seeding effect on tau using biosensor cells. In contrast to the control, disaggregation experiments showed fewer Aβ plaques with our lead molecules (compounds 6T and 14T). Pharmacokinetics (PK) mice studies demonstrated that these two thiourea-based small molecules have the potential to cross the blood-brain barrier in rodents. Urea and thiourea linkers could be further improved for their PK parameters and studied for the anti-inclusion, anti-seeding, and disaggregation effects using transgenic mice models of neurodegenerative diseases.

Chemiexcitation Acceleration of 1,2‐Dioxetanes by Spiro‐Fused Six‐Member Rings with Electron‐Withdrawing Motifs

AbstractThe chemiluminescent light‐emission pathway of phenoxy‐1,2‐dioxetane luminophores attracts growing interest within the scientific community. Dioxetane probes undergoing rapid flash‐type chemiexcitation exhibit higher detection sensitivity than those with a slow glow‐type chemiexcitation rate. We discovered that dioxetanes fused to non‐strained six‐member rings, with hetero atoms or inductive electron‐withdrawing groups, present both accelerated chemiexcitation rates and elevated chemical stability compared to dioxetanes fused to four‐member strained rings. DFT computational simulations supported the chemiexcitation acceleration observed by spiro‐fused six‐member rings with inductive electron‐withdrawing groups of dioxetanes. Specifically, a spiro‐dioxetane with a six‐member sulfone ring exhibited a chemiexcitation rate 293‐fold faster than that of spiro‐adamantyl‐dioxetane. A turn‐ON dioxetane probe for the detection of the enzyme β‐galactosidase, containing the six‐member sulfone unit, exhibited a S/N value of 108 in LB cell growth medium. This probe demonstrated a substantial increase in detection sensitivity towards E. coli bacterial cells expressing β‐galactosidase, with an LOD value that is 44‐fold more sensitive than that obtained by the adamantyl counterpart. The accelerated chemiexcitation and the elevated chemical stability presented by dioxetane containing a spiro‐fused six‐member ring with a sulfone inductive electron‐withdrawing group, make it an ideal candidate for designing efficient turn‐on chemiluminescent probes with exceptionally high detection sensitivity.

Chemiexcitation Acceleration of 1,2-Dioxetanes by Spiro-Fused Six-Member Rings with Electron-Withdrawing Motifs.

The chemiluminescent light-emission pathway of phenoxy-1,2-dioxetane luminophores attracts growing interest within the scientific community. Dioxetane probes undergoing rapid flash-type chemiexcitation exhibit higher detection sensitivity than those with a slow glow-type chemiexcitation rate. We discovered that dioxetanes fused to non-strained six-member rings, with hetero atoms or inductive electron-withdrawing groups, present both accelerated chemiexcitation rates and elevated chemical stability compared to dioxetanes fused to four-member strained rings. DFT computational simulations supported the chemiexcitation acceleration observed by spiro-fused six-member rings with inductive electron-withdrawing groups of dioxetanes. Specifically, a spiro-dioxetane with a six-member sulfone ring exhibited a chemiexcitation rate 293-fold faster than that of spiro-adamantyl-dioxetane. A turn-ON dioxetane probe for the detection of the enzyme β-galactosidase, containing the six-member sulfone unit, exhibited a S/N value of 108 in LB cell growth medium. This probe demonstrated a substantial increase in detection sensitivity towards E. coli bacterial cells expressing β-galactosidase, with an LOD value that is 44-fold more sensitive than that obtained by the adamantyl counterpart. The accelerated chemiexcitation and the elevated chemical stability presented by dioxetane containing a spiro-fused six-member ring with a sulfone inductive electron-withdrawing group, make it an ideal candidate for designing efficient turn-on chemiluminescent probes with exceptionally high detection sensitivity.

Sintesis dan Karakterisasi Solid Polymer Electrolyte (SPE) Berbasis Nanofiber Selulosa untuk Menunjang Baterai Litium Berdensitas Tinggi dan Ramah Lingkungan

Lithium battery as one of the energy storage has two important elements, namely electrodes and electrolyte. Electrolyte is a part of the battery element that has undergone many developments. In this study, the manufacture of electrolytes in the form of Solid Polymer Electrolyte (SPE) was carried out by utilizing the abundant availability of nata de coco. The nanofibrous cellulose structure in Bacterial Cellulose (BC) nata de coco has the advantages of good porosity, flexibility in surface functionality, compact porous structure that provides abundant ion pathways and hetero atoms (oxygen atoms) with free electron pairs that facilitate ionic conduction. The SPE synthesis process was carried out by varying the soaking time of nata de coco in ethanol, namely 1, 2 and 3 days to determine the structure with optimal results. FTIR characterization results show the synthesis of cellulose nanofiber has the same groups as commercial cellulose groups in the form of O-H, C-H, C=O and C-O. CV characterization results show the SPE electrolyte has good redox properties, especially in the 2-day variation with the highest specific capacitance. The EIS test showed the lowest resistance in the 1-day variation sample with a conductivity of 0.017 ohm-1.

Ability of transition metal and hetero atoms co-doped SWCNTs for hydrogen adsorption: A DFT study

The hydrogen adsorption capability of functionalized armchair single walled carbon nanotubes (SWCNTs) has been studied to analyze their candidature for hydrogen sensing and storage. Our proposed approach serves as a frame for assessing and prophesying the scope of Au/Ag/Cu/boron/nitrogen atoms doped/co-doped CNTs in the field of hydrogen energy. To corroborate the efficacy of our approach, we perform an ample investigation using armchair SWCNTs having chirality (5,5). Applying our criteria, we thoroughly screen Au/Ag/Cu/boron/nitrogen doped/co-doped in SWCNTs and analyze structural stability, electrical stability and thermo-dynamical stability of the substrates. Our results are based on the calculations of binding energy, bond distances, Bader's Topological Analysis, band gaps, electrophilicity, Density of states (DOS), Mulliken and Natural bond orbital (NBO) charge distribution, adsorption energies, adsorption enthalpy and Gibbs free energy of all the species by utilizing density functional theory (DFT). We found that Au-BCNT, Au-Ag-CNT and Au-Cu-CNT structures have good hydrogen sensing properties, whereas, Ag-NCNT shows better hydrogen storage among all studied species with an average adsorption energy of −0.815eV/H2 and it can adsorb four hydrogen molecules at 298.15K temperature and 1atm pressure. The storage of H2 in Ag-NCNT is reversible at desorption temperature of 605K–172K.

Electrode kinetics for the reduction of central hetero VinV and framework addenda VoutV and WVI atoms in the [VinVoutW11O40]4− polyoxometalate: Comparisons with [SVoutW11O40]3− and [VinW12O40]3−

The electrode kinetics associated with the polyoxometalate (POM) [VinVoutW11O40]4-/5-/6−, [VinW12O40]3-/4-/5− and [SVoutW11O40]3-/4-/5− (Vin – central hetero vanadium atom, Vout – framework addenda vanadium atom) reduction processes in CH3CN (0.10 M [Bu4N][PF6]) have been determined by Fourier Transformed large amplitude alternating current voltammetry at a glassy carbon electrode. [VinVoutW11O40]4− provides an interesting situation where both the VinV and VoutV vanadium atoms can be reduced to the VIV state. The heterogeneous charge transfer rate constant kVout0′ value for the framework [VinVVoutVW11O40]4−/[VinVVoutIVW11O40]5− process of 0.15 cm s−1 (reversible formal potential E0ʹ = −223 mV vs Fc0/+) is almost ten times that of 0.020 for the kVin0′ (E0ʹ = −1027 mV vs Fc0/+) one associated with the central [VinVVoutIVW11O40]5−/[VinIVVoutIVW11O40]6− reaction. The significant decrease in the electrode kinetics for the process involving reduction of the central vanadium could in principle be attributed to differences in the Vin and Vout coordination geometry or a longer distance required for electron transfer between the electrode surface and Vout. However, neither of these factors is considered to be dominant as kVin0′ associated with the [VinVW12O40]3−/[VinIVW11O40]4- reaction is 0.19 cm s−1 (E0ʹ is −114 mV vs Fc0/+). With this POM, the more negative second process (E0ʹ = −918 mV vs Fc0/+) is associated with a WVI/WV framework reduction with a k0ʹ value of 0.080 cm s−1. With the second control POM, [SVoutW11O40]3−, the initial very fast framework VoutV/VoutIV reduction step (E0ʹ = 145 mV vs Fc0/+) has a k0ʹ value of 0.19 cm s−1 and is followed at considerably more negative potentials (E0ʹ = −1343 mV vs Fc0/+) by the slightly slower framework WVI/WV process with k0ʹ = 0.13 cm s−1. Thus, the k0ʹ values are most strongly influenced by the negative charge (n value) associated with the POMn-(/n+1)- reaction, being close to reversible when n = 3 as in the [VinW12O40]3−4− and [SVoutW12O40]3−/4− reactions, but much slower when n = 5 as in the case of the [VinVoutW11O40]5-/6- reaction. Accordingly, the initial reduction step is always faster than the second one that occurs at more negative potentials, irrespective of whether Vin, Vout or W are reduced. In the case of thermodynamically relevant E0ʹ values, it has been established that a strong correlation exists with the n value in POMn-/(n+1)− process. It is now shown that a similar correlation of k0ʹ with n applies.

Exploring the Ultralong Lifetime of Self‐matrix 1,10 Phenanthroline and Boron‐Based Room Temperature Phosphorescence Carbon Dots for Multiple Applications

AbstractRoom temperature phosphorescence carbon dots (RTP CDs) are one of the newly investigated nanomaterials because of their remarkable optical characteristics. They are widely utilized in many versatile optoelectronic and security applications. Apart from synthesis, one of its challenging attributes is its lifetime at room temperature. Here, a straightforward and quick heating approach is presented for synthesizing self‐matrix 1,10 phenanthroline and boron‐based RTP CDs. 1,10 phenanthroline is utilized as an aromatic and hetero atom containing carbon precursor and boric acid is used as a passivating to stabilize the triplet excitons and prevent nonradiative deactivation. Various characterization techniques like TEM, XRD, FTIR, UV–vis, PL, and elemental analysis (ICP and CHNS) have been used to study the properties of self‐matrix RTP CDs. The RTP CDs exhibited excellent blue‐green emission when excited at 302 nm. Compared to the available literature, the novelty of this work is observed from its high naked eye phosphorescence characteristic of ≈22 s with an average lifetime of ≈ 2.4 s at 302 nm, making them ultralong self‐matrix RTP CD material. Due to their exceptional qualities, the self‐matrix RTP CDs have been widely employed for various applications, including information encryption decryption, phosphor for LEDs, anticounterfeiting, and water sensitivity analysis.

Copper (II) and cobalt (II) bis(hexafluoroacetylacetonate) coordination complexes with N-styrylbenzimidazole

The study considers metal complexes based on N-styrylbenzimidazole as compounds having significant pharmacological properties The work is aimed at examining the crystal structure and electronic structure of transition metal bis(hexafluoroacetylacetonate) complexes (copper (II) (complex A) and cobalt (II) (complex B)) with N-styrylbenzimidazole using X-ray diffraction analysis and ultraviolet spectroscopy. The X-ray diffraction analysis was used to prove bipyramidal coordination in copper (II) and cobalt (II) bis(hexafluoroacetylacetonate) complexes with N-styrylbenzimidazole. The atoms of copper (II) and cobalt (II) in the complexes exhibit an unusual for β-diketonate complexes distorted square-planar coordination, while the chelate cycles in M(hfacac)2L are characterized by anomalously large kink angles. Thus, for the copper (II) bis(hexafluoroacetylacetonate) complex, the kink angle of the O3∙∙∙O4 interaction for the equatorially positioned ligand is 29.47°, while for the axially positioned ligand, the kink angle of the O1∙∙∙O2 interaction is 19.13°. For the cobalt (II) bis(hexafluoroacetylacetonate) complex, these angles are 22.10 and 19.50°, respectively. Electron spectroscopy was used to examine the electronic structure of the specified complexes. The following types of electronic transitions were identified: π→π*-transitions primarily localized on ligands, as well as transitions caused by electron transfer from the p-orbital of the hetero nitrogen atom of the styrylbenzimidazole cycle to the d-orbital of metal ions, and n→π transition localized on the imidazole ring. For each of the complexes, d-d* transitions between the molecular orbitals of the corresponding metal ion were localized in the long wavelength part of the spectrum.

N-Containing Porous Carbon-Based MnO Composites as Anode with High Capacity and Stability for Lithium-Ion Batteries.

MnO has attracted much attention as the anode for Li-ion batteries (LIBs) owing to its high specific capacity. However, the low conductivity limited its large application. An effective solution to solve this problem is carbon coating. Biomass carbon materials have aroused much interest for being low-cost and rich in functional groups and hetero atoms. This work designs porous N-containing MnO composites based on the chemical-activated tremella using a self-templated method. The tremella, after activation, could offer more active sites for carbon to coordinate with the Mn ions. And the as-prepared composites could also inherit the special porous nanostructures of the tremella, which is beneficial for Li+ transfer. Moreover, the pyrrolic/pyridinic N from the tremella can further improve the conductivity and the electrolyte wettability of the composites. Finally, the composites show a high reversible specific capacity of 1000 mAh g-1 with 98% capacity retention after 200 cycles at 100 mA g-1. They also displayed excellent long-cycle performance with 99% capacity retention (relative to the capacity second cycle) after long 1000 cycles under high current density, which is higher than in most reported transition metal oxide anodes. Above all, this study put forward an efficient and convenient strategy based on the low-cost biomass to construct N-containing porous composite anodes with a fast Li+ diffusion rate, high electronic conductivity, and outstanding structure stability.

Review On Strategies For the Design and Synthesis of Flower‐Like Bi2WO6 and BiOX (X=F, Cl, Br, I) Composites for Photocatalytic Environmental Remediation

AbstractIn latest events, water pollution has posed an immense threat, and its sustainable treatment is a topic of concern. Among myriad of water treatment, research community has lensed towards sustainable heterogeneous photocatalysis especially, inorganic semiconductors. Bismuth tungstate a pristine Aurivillius compound with unique crystal structure, exceptional photochemical stability, and strong redox abilities but minimum visible light absorption and quick carrier recombination are its caveats, these caveats are circumvented by synthesizing BiOX (X=F, Cl, Br and I) composites with surface modifiers, doping with hetero atoms (metals and non‐metals), construction of the heterojunction and amalgamation of carbon materials. The heart of this review is strategic engineering of flower‐like morphology photocatalyst synthesis and optical properties, it also discusses the charge transfer kinetics, photocatalytic performance, and durability. The flower‐like morphology highlighted in this review is due to its ability to harvest light, providing larger specific surface area which introduces more active sites and efficient excitons generation. The comprehensive tabulated data in this review will help the actively engaged research community in Bismuth heterogenous photocatalysis. It also sheds light on the future view of environmental remediation via photocatalytic developments.

Synthesis, characterization and evaluation of new anti-inflammatory iron charge transfer complexes

The novelty and the essential purpose of this research is the preparation of new anti-inflammatory iron complexes in water green solvent using critical micelle concentration of anionic surface active agent (SAA). Three new anti-inflammatory iron complexes have been prepared. Thiophene-electron (es) donor (D) Schiff base (2-(2-OH-benzylidene)-amino)-4, 5, 6, 7-tetrah ydrobenzo[b] thiophene-3-carbonitrile) has been prepared. Molecular structures of all samples were confirmed based on CNH analysis, 1H NMR and 13C NMR spectra. The molecular structure of Schiff base is further confirmed by computational chemistry using the DFT-B3LYP method, 6-31G (d) basis set. Observed and simulated 1H NMR, UV–Vis. IR/Raman spectra confirmed the molecular structure of D. This Schiff base is intercalated to ferric chloride (FeCl3) giving pure iron charge transfer complex (CTCs). In vitro and kinetic studies confirmed Fe-CTC complexes had (concentration-dependent) potent antimicrobial-, good anti-inflammatory activities. Free radical scavenging activity nitrous oxide (NO.) of Fe (III)CTCs is attributed to geometry Fe(III) ions as distorted octahedral (either monoclinic or triclinic single crystals) via functional groups (-C]N–O, NH2). Elemental analysis and EDS spectra confirmed strong binding between iron and hetero atoms (N, S, O) of D molecules.

Comprehensive ecotoxicological assessment of pesticides on multiple avian species: Employing quantitative structure-toxicity relationship (QSTR) modeling and read-across

The rapid increase in the use of pesticides is driven by the growing demand in the agricultural sector. However, the widespread application of these pesticides and their inherent toxicity have significant repercussions on the ecosystem, particularly impacting animal and bird species. In this present study, we have developed four 2D quantitative structure-toxicity relationships (QSTRs) models for four different avian species using the largest number of available experimental data points to date employing the partial least squares (PLS) algorithm. Furthermore, we have also performed the read-across algorithm to improve the test set results. Based on the information derived from the models, it was found that hydrophilic characteristics, the presence of molecular branching and thio imide groups impact negatively to the pesticide toxicity, while the presence of phosphate group, presence of halogens viz. chlorine and bromine atoms, presence of hetero atoms, high molecular weight, presence of bridgehead atoms, presence of secondary aliphatic amide and fragments like RCONHR escalates avian toxicity. The developed QSTR models were further employed to predict the Pesticide Properties DataBase (PPDB) for all four avian species as a measure of data gap-filling and risk assessment. Thus, the developed models can be utilized for eco-toxicological data-gap filling, prediction of toxicity of untested pesticides as well as the development of novel and safe environmental-friendly pesticides.

N, S Co-doped carbon anchored Co9S8 cathode: Advancing sustainable energy through efficient Li–CO2 Mars batteries

Owing to their higher capacity and ability to address global warming, Li–CO2 batteries have potential for next-generation energy storage systems on Earth and for space applications. However, the key drawbacks of high overpotential and low cyclability of Li–CO2 batteries substantially hinder their practicality. In this study, we develop uniquely designed cobalt sulfide (Co9S8) nanoparticles anchored onto the N, S dual-doped hetero atoms graphitized mesoporous carbon (NSC) as a low-cost but highly effective cathodic catalyst for Li–CO2 batteries with a large number of active sites with enhanced conductivity. The as-developed Li–CO2 batteries under simulated Martian gas atmosphere conditions (Li–CO2 Mars) display a high discharge capacity and exceptional rate performance. The Li–CO2 Mars battery offers a high discharge capacity of 15147 mAh g−1 at 500 mA g−1 current density and maintains a stable performance over 120 cycles for a limited capacity of 500 mAh g−1. Further, the first-principle calculations provide a deeper understanding of the reaction pathways during discharging and charging. These results create new avenues for designing novel catalysts for high-performance Li–CO2 Mars batteries for their use in interplanetary missions.

Spin-mediated promotion of Co catalysts for ammonia synthesis.

Over the past two decades, there has been growing interest in developing catalysts to enable Haber-Bosch ammonia synthesis under milder conditions than currently pertain. Rational catalyst design requires theoretical guidance and clear mechanistic understanding. Recently, a spin-mediated promotion mechanism was proposed to activate traditionally unreactive magnetic materials such as cobalt (Co) for ammonia synthesis by introducing hetero metal atoms bound to the active site of the catalyst surface. We combined theory and experiment to validate this promotion mechanism on a lanthanum (La)/Co system. By conducting model catalyst studies on Co single crystals and mass-selected Co nanoparticles at ambient pressure, we identified the active site for ammonia synthesis as the B5 site of Co steps with La adsorption. The turnover frequency of 0.47 ± 0.03 per second achieved on the La/Co system at 350°C and 1 bar surpasses those of other model catalysts tested under identical conditions.

Expanding Luminescence Horizons in Macropolyhedral Heteroboranes

AbstractLuminescence is observed in three novel macropolyhedral nineteen‐ and eighteen‐vertex chalcogenaboranes: Se2B17H17 (1), SeB17H19 (3) and SeB18H20 (4). This led us to the recognition that previously published macropolyhedral heteroborane species might also exhibit luminescence. Thus, the known nineteen‐ and eighteen‐vertex dithiaboranes S2B17H17 (2), n‐S2B16H16 (5) and i‐S2B16H16 (6) were synthesised and also found to exhibit a range of luminescent properties. These macropolyhedral species are very different from the previously unique fluorescent binary borane B18H22 in terms of their structural architectures, by the presence of borane cluster hetero atoms, and, as in the cases of 5 and 6, that their synthetic origins are not derived simply through the modification of B18H22 itself. They consequently greatly expand the possibilities of finding new luminescent inorganic borane species.

Expanding Luminescence Horizons in Macropolyhedral Heteroboranes.

Luminescence is observed in three novel macropolyhedral nineteen- and eighteen-vertex chalcogenaboranes: Se2B17H17 (1), SeB17H19 (3) and SeB18H20 (4). This led us to the recognition that previously published macropolyhedral heteroborane species might also exhibit luminescence. Thus, the known nineteen- and eighteen-vertex dithiaboranes S2B17H17 (2), n-S2B16H16 (5) and i-S2B16H16 (6) were synthesised and also found to exhibit a range of luminescent properties. These macropolyhedral species are very different from the previously unique fluorescent binary borane B18H22 in terms of their structural architectures, by the presence of borane cluster hetero atoms, and, as in the cases of 5 and 6, that their synthetic origins are not derived simply through the modification of B18H22 itself. They consequently greatly expand the possibilities of finding new luminescent inorganic borane species.

Carbon quantum dots in bioimaging and biomedicines.

Carbon quantum dots (CQDs) are gaining a lot more attention than traditional semiconductor quantum dots owing to their intrinsic fluorescence property, chemical inertness, biocompatibility, non-toxicity, and simple and inexpensive synthetic route of preparation. These properties allow CQDs to be utilized for a broad range of applications in various fields of scientific research including biomedical sciences, particularly in bioimaging and biomedicines. CQDs are a promising choice for advanced nanomaterials research for bioimaging and biomedicines owing to their unique chemical, physical, and optical properties. CQDs doped with hetero atom, or polymer composite materials are extremely advantageous for biochemical, biological, and biomedical applications since they are easy to prepare, biocompatible, and have beneficial properties. This type of CQD is highly useful in phototherapy, gene therapy, medication delivery, and bioimaging. This review explores the applications of CQDs in bioimaging and biomedicine, highlighting recent advancements and future possibilities to increase interest in their numerous advantages for therapeutic applications.

Probing the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil via molecular dynamics simulation

High content of asphaltenes and waxes leads to the high pour point and the poor flowability of heavy oil, which is adverse to its efficient development and its transportation in pipe. Understanding the interaction mechanism between asphaltene-wax is crucial to solve these problems, but it is still unclear. In this paper, molecular dynamics simulation was used to investigate the interaction between asphaltene-wax and its effects on the crystallization behavior of waxes in heavy oil. Results show that molecules in pure wax are arranged in a paralleled geometry. But wax molecules in heavy oil, which are close to the surface of asphaltene aggregates, are bent and arranged irregularly. When the mass fraction of asphaltenes in asphaltene-wax system (ωasp) is 0–25 wt%, the attraction among wax molecules decreases and the bend degree of wax molecules increases with the increase of ωasp. The ωasp increases from 0 to 25 wt%, and the attraction between asphaltene-wax is stronger than that among waxes. This causes that the wax precipitation point changes from 353 to 333 K. While the ωasp increases to 50 wt%, wax molecules are more dispersed owing to the steric hindrance of asphaltene aggregates, and the interaction among wax molecules transforms from attraction to repulsion. It causes that the ordered crystal structure of waxes can't be formed at normal temperature. Simultaneously, the asphaltene, with the higher molecular weight or the more hetero atoms, has more obvious inhibition to the formation of wax crystals. Besides, resins also have an obvious inhibition on the wax crystal due to the formation of asphaltene-resin aggregates with a larger radius. Our results reveal the interaction mechanism between asphaltene-wax, and provide useful guidelines for the development of heavy oil.