Aromatic Structures Research Articles

Synthesis of a Conceptual New Single-Ion Conducting Polymer Electrolyte for All-Solid-State Batteries

The increasing global population and the rapid change in climatic conditions strengthens the demand for a more efficient handling of energy consumption and energy storage technologies. In this context, all-solid-state batteries (ASSBs) as next-generation rechargeable lithium-ion batteries offer an improved energy and power density based on the integration of novel separators and electrode materials. In comparison to their liquid representatives, ASSBs provide a higher intrinsic safety via non-flammable components and in addition greater long-term durability. In relation to common electrolyte classes, solid polymers stand out due to their good mechanical flexibility, easy film-formation ability, good contact supply between cell components, and lower production costs, favoring the application as electrolytes, protective coatings, as well as additives in cathode composites. Among a variety of polymers, poly(ethylene oxide) (PEO) is a well-studied and established host polymer due to its great ability to dissolve lithium salts like LiBH4, LiPF6 or LiTFSI. Based on a low glass transition temperature (Tg) of about - 60 to - 50 °C, PEO shows a high degree of polymer chain flexibility which facilitates the migration of the lithium cations through the solid electrolyte. Nevertheless, its semi-crystalline character often leads to low conductivities below its melting point (Tm) of around 60 °C, making pure PEO unattractive as solid electrolyte. Copolymerization, the addition of a small amount of solvent to produce so called gel polymer electrolytes, the addition of some plasticizers, or the interplay of polymer and inorganic fillers try to counteract this trend. The synthetical concept behind this work is aiming to benefit from the flexible nature of PEO, and at the same time to improve the ionic conductivities and especially the lithium migration by structural realignment away from a dual-ion towards a single-ion conducting polymer electrolyte (SICPE). The polar PEO-backbone ensures polymer chain mobility, whereas a rigid aromatic structure unit as side chain bears the fixed anionic group. The immobilization of the anionic charges on the polyether backbone tends to guide the electrolyte to higher lithium transference numbers, fewer polarization effects, and the suppression of dendrite growth, resulting in an overall improved cell performance. Synthesis steps via the novel SICPE are characterized with the help of nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Thermal analyses of the homopolymer already show the positive influence of the flexible PEO-backbone by lowering the Tg from 100 to 150 °C for related aliphatic derivatives down to 60 to 80 °C in our case. On the basis of electrochemical impedance spectroscopy (EIS) measurements, the interplay of chemical, thermal, and electrochemical key properties is investigated. The gained results tend to open a discussion panel concerning occurring challenges for solid-state polymer electrolytes and the interdependencies between electrolyte constitution and polymer characteristics.

Molecular simulation study of microstructural evolution during low-temperature oxidation of coal

In this study, industrial analysis, 13C NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and in-situ infrared spectroscopy were employed to determine the elemental composition and structure of Tingnan coal. The peak area, pore volume, and specific surface area were used as the main parameters to investigate the structural changes of coal molecules and pore evolution during low-temperature coal oxidation, using an automated surface area and pore size analyzer. The analysis revealed that with increasing oxidation degree, the CH groups in the aromatic structure gradually decreased, while the total content of oxygen-containing functional groups such as alcohols, phenols, carboxyls, and carbonyls remained relatively constant. However, the relative content of hydroxyl groups and ether linkages increased with increasing oxidation temperature. Additionally, coals with different oxidation degrees exhibited well-developed micropores, and the specific surface area gradually decreased while the pore size increased with temperature. Molecular models of Tingnan coal in its original state and oxidized at temperatures of 50 °C, 70 °C, and 110 °C were constructed using Materials Studio software. Based on these models, pores with diameters of 2.79 nm, 3.07 nm, 3.07 nm, and 3.11 nm and a length of 4.5 nm were constructed using the coal molecular structure as the pore walls.

Insight into interactions between microplastics and fulvic acid: Mechanisms affected by microplastics type

Microplastics (MPs) can interact with dissolved organic matter (DOM), a common component found in the environment. However, the effect of MPs type on its interaction with DOM has not been systematically studied. Therefore, the binding properties of different MPs with fulvic acid (FA) were explored in this study. The results showed that polypropylene (PP) and polyethylene (PE) had higher adsorption affinity for FA than polystyrene (PS) and polyvinyl chloride (PVC). The interaction between MPs and FA conformed to the pseudo-first-order model and Freundlich model (except PS). The interaction mechanisms between various MPs tested in this paper and FA are considered to be different. PP, PE and PS interacted with the aromatic structure of FA and were entrapped in the FA polymers by the carboxyl groups and CO bonds, resulting in a highly conjugated co-polymer, suggesting that oxygen-containing functional groups played a key role. However, it was assumed that the interaction between PVC and FA was more likely to be caused by hydrophobic interaction. This research will help to enhance our comprehension of the environmental behavior of MPs and their interaction with the DOM specifically.

Adsorption and aggregation of Cu2+ on carboxymethylated sugarcane bagasse: Adsorption behavior and mechanism

Abundant biomass resources provide us with sufficient material basis, while a large amount of bio-waste is also produced and the high-value utilization of bio-waste is still highly desirable. Herein, we reported a facile one-pot fabrication approach towards efficient utilization of sugarcane bagasse via carboxymethylation to adsorb and recycle Cu2+ ions. The modified sugarcane bagasse possessed outstanding adsorption efficiency, with a maximum capacity of 263.7 mg g−1, owing to the functional groups such as carboxyl and hydroxyl groups, as well as aromatic structure. It was noted that the carboxymethylated sugarcane bagasse (MSB40) swelled rapidly when suffering Cu2+ ions solution, and more adsorption sites were available since the physical diffusion barrier was removed, thereby enhancing the absorption capacity. Interestingly, Cu2+ ions could induce the aggregation of MSB40 due to the Cu2+ ions compress colloid double layer, neutralizes surface charges, which benefited the following separation process. Ultimately, copper oxide was recovered and the purity reached 97.9%. Additionally, in the presence of both Ca2+ and Mg2+ ions, MSB40 exhibited excellent selectivity for the adsorption of Cu2+ ions. This strategy offers a facile and novel clue for the high-value utilization of bio-waste and the recovery of copper for biomaterial and environmental applications.

Emission characteristics of cellulosic jet biofuel blend under laminar and turbulent combustion

Alternative biofuels have the potential to reduce greenhouse gas emissions and particulate matter due to free of aromatics compared to traditional petroleum-based aviation fuel. The potential mitigating emission of hydrothermal-condensation-hydrotreating jet biofuel (HCHJ) derived from agriculture residue was investigated. The effects of aviation biofuel components, blend ratio and equivalent ratio on emission characteristics were conducted by Premixed Pre-evaporated Bunsen burner (PPBB) for laminar combustion and ZF850 jet engine for turbulent combustion. In compositions, HCHJ had a higher concentration of cycloparaffins (mostly in C8–C10) while petroleum-based aviation fuel (RP-3) had a higher concentration of alkylbenzenes (mostly in C8–C11). In laminar combustion, HCHJ and both 50% blend HCHJ appear no unburned hydrocarbon (UHC) due to low aromatics content and no sulfur in the biofuel. Moreover, there were no significant differences in NO and NO2 concentration for HCHJ and HCHJ blends. In turbulent combustion, HCHJ blends and RP-3 were compared engine emissions at various state points. Considering all complex effects of fuel and combustion environment, HCHJ blend had a noticeable reduction in PM2.5 emissions in comparison with RP-3 due to their lower aromatics and sulfur content. As HCHJ is similar to RP-3 in C/H ratio, density and heat value and the different aromatics contents have different tendencies to generate PM2.5 at different condition, PM2.5 emission is not only related with the total aromatic content and individual aromatic structure but also the combustion environment at thrust setting and coexisting pollutants including NOx and UHC emissions. CO and NOx emission indicated that both of turbulent state and fuel type influence emissions. HCHJ blend can be benefit for PM2.5 reduction and combustion efficiency growth. PM2.5 reduction can be obtained 77.5% at 10% HCHJ blend and 9.5% at 5% HCHJ blend while combustion efficiency can be obtained 0.05% at 5% HCHJ blend and 0.36% at 10% HCHJ blend through all thrust output.

Characterization of Sulfur-Rich Microbial Organic Matter in Jurassic Carbonates Using Laser-Assisted Mass Spectrometry.

Laser desorption-ionization mass spectrometry (MS) shows great potential for in situ molecular analysis of planetary surfaces and microanalysis of space-returned samples or (micro)fossils. Coupled with pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) in ESA's ExoMars project, this technique could help assess further the origin of sulfur-bearing organic matter (OM) recently detected on Mars. To unravel this potential, we analyzed sulfurized microbial OM from ca. 150 million year-old carbonates with laser desorption-ionization mass spectrometry (single- and two-step: LDI-MS and L2MS), in comparison with time-of-flight secondary-ion mass spectrometry (ToF-SIMS), gas chromatography-mass spectrometry (GC-MS), and Py-GC-MS. We show that LDI-MS and L2MS readily detect sulfur-bearing moieties such as (alkyl)thiophenes and (alkyl)benzothiophenes. The mineral matrix, however, made the identification of sulfur-bearing molecules challenging in our L2MS experiment. The dominance of small aromatic hydrocarbons (≤14 carbons) in the LDI-MS and L2MS of the extracted soluble and insoluble OM and of the bulk rock is consistent with the low thermal maturity of the sediment and contrasts with the predominance of larger polycyclic aromatic structures commonly observed in meteorites with these techniques. We detected inorganic ions, in particular VO+, in demineralized OM that likely originate from geoporphyrins, which derive from chlorophylls during sediment diagenesis. Finally, insoluble OM yielded distinct compositions compared with extracted soluble OM, with a greater abundance of ions of mass-to-charge ratio (m/z) over 175 and additional N-moieties. This highlights the potential of laser-assisted MS to decipher the composition of macromolecular OM, in particular to investigate the preservation of biomacromolecules in microfossils. Studies comparing diverse biogenic and abiogenic OM are needed to further assess the use of this technique to search for biosignatures.

The occurrence of oxygen in lignite derivatives and residue from catalytic ethanolysis of Shengli lignite under an inert atmosphere

Lignite is rich in aromatic structures and oxygen atoms, which have the potential to produce organic oxygen-containing compounds. Investigating the cleavage of the >CH–O– bond and oxygen transfer behavior in the catalytic ethanolysis of lignite is indispensable. Herein, A difunctional catalyst composed of HZSM-5 and Ni nanoparticles was fabricated for splitting the >CH–O– bond in the absence of H2. It is found that the >CH–O– bond in Benzyloxy benzene (BOB) could be completely broken with ethanol in the absence of H2. Ethanol can be activated and release H+ over Ni/HZSM-5, which transfers and attacks the >CH–O– bond for obtaining toluene and phenols. The soluble portions from ethanolysis of Shengli lignite were analyzed with fourier transform infrared spectrometer and gas chromatograph/mass spectrometer for tracking the migration of oxygen atoms. It is apparent that esters with higher relative content (32.6 %) were detected in soluble portion 1 (SP1), while alcohols (35.3 %) dominate catalytically soluble portion 1 (CSP1). Moreover, a large number of alkyl-substituted phenols were identified in both SP1 and CSP1. Additionally, related analysis of SL and residual coal manifested that >CH–O– and >C=O bonds were the main forms of existence in residue from catalytic ethanolysis of SL. In a word, exploring the occurrence of oxygen in catalytic ethanolysis of lignite has the potential to produce lignite-derived organic oxygenated chemicals.

Study on the catalysis of copper-based compounds on coal spontaneous combustion and its mechanism

ABSTRACTTo study the effect of the copper element in coal on the spontaneous combustion process of coal, corresponding copper-containing compounds were added to the coal-based on their occurrence state, and thermodynamic experiments and in-situ diffuse reflectance infrared spectroscopy experiments were conducted. Thermodynamic oxidation experiments have shown that the catalytic effects of Cu (NO3)2, CuCl2, CuCl, and Cu2O on three types of coal with different degrees of metamorphism are mainly reflected in the accelerated oxidation stage. After adding copper-containing compounds, the ignition temperature of coal decreased by 22.1°C to 134.4°C, the heat release increased by 1.33 to 3.19 times, and the CO emission and oxygen consumption rate also increased. CuCl has the greatest impact on the ignition point temperature of coal and increases the oxygen consumption rates of DNH and TS by 2.32 and 1.51 times that of raw coal. CuCl2 has the strongest catalytic effect on coal oxidation heat release. Through in-situ diffuse reflectance infrared spectroscopy experiments, it was found that the reaction rate of fatty hydrocarbons in the oxidation process of three types of coal with the addition of copper-containing compounds increased to 1.3–3 times that of raw coal, and the oxidation rate of oxygen-containing functional groups also significantly increased, while the cracking temperature of aromatic structures significantly decreased. This is because copper ions, as strong free radicals, induce free radical chain reactions in coal and exhibit a strong promoting effect on the coal oxygen reaction process.

Lignin demethylation enabled robust and reprocessable bio-polyurethane elastomer with adaptable cross-linking network

The development of sustainable bio-polyurethanes (bio-PU) from nonfood lignin has been attracting extensive attention owing to the abundant reserves, stable aromatic structures, and rich hydroxyls of lignin. However, exploiting a high-performance lignin-based PU integrating excellent mechanical properties with reprocessability is still a challenge. Herein, we proposed a dynamic phenolic-carbamates to construct robust and reprocessable bio-PU elastomers based on the reaction of phenolic lignin (PL) with isocyanate. Benefiting from the low Mw of 1692 Da and the abundant phenolic hydroxyls of 8.3 mmol/g, the adaptable cross-linking network consisting of dynamic hydrogen bonds and phenolic-carbamates were formed by PL. The synthesized phenolic lignin-based PU (PLPU) displayed tunable mechanical properties via adjusting PL substitution amount. The tensile strength, modulus and toughness of PLPU reached 58.8 MPa, 1350.3 MPa, and 57 MJ/m3 when the substitution amount of PL was 70%, respectively. Importantly, the reversible cross-linking structure endowed PLPU with excellent multi-reprocessability. After 5 reprocessing cycles, the retention ratio of strength, breaking elongation, modulus and toughness was 87.6%, 58.9%, 218.1% and 63.3%, respectively, which were 1.6, 1.1, 3.5, 2.2 times higher than those of commercial lignin-based polyurethane (CLPU). Therefore, this work not only presents a robust and multi-reprocessable lignin-based PU elastomer with high substitution amount, but also provides a promising sustainable alternative to replace petroleum-based plastic.

Accessing Indenoazulenes via a Gold‐Catalysed Cyclisation of Cycloheptatrienyl‐Substituted 1,5‐Diynes

AbstractHerein we report that cycloheptatrienyl‐substituted 1,5‐diynes with aromatic backbones undergo a gold‐catalysed 5‐endo‐dig cyclisation to give 11H‐indeno‐[2,1‐a]azulenes at room temperature. This methodology complements the established range of aromatic structures obtained from gold‐catalysed conversions of differently substituted 1,5‐diynes accessed via highly reactive cationic intermediates. We have demonstrated the scope of the reaction and have assessed the possibility of further functionalisation of the indenoazulene scaffold. Additionally, we have studied the optical and electrochemical properties as well as the frontier molecular orbitals of this structural motif by both spectroscopic and theoretical means.

Assessing variances in the impact of intrinsic minerals on NO and N2O precursors during sludge pyrolysis

This study proposed a novel strategy to control nitrogen oxides (NOx) precursors by directing nitrogen to adhere to the fuel-N→NH3→N2 pathway. The research aimed to illuminate the regulatory effects of CaO, Fe2O3, and their mixtures on NO and N2O precursors (NH3, HCN, and HNCO) during sludge pyrolysis, further sought to establish scientific correlations with varying temperatures and differentiate their impact. The findings indicated that unlike NH3, HNCO is generated from the cleavage of amides, sharing its origin with HCN. Notably, the sensitivities of three conditioners to different functional groups result in distinct impacts on precursor emissions. CaO interacted with –OH and N-H functional groups, releasing NH3. Fe2O3, being more responsive to C-H and C-C groups, contributed to HNCO emission. At 750 °C, a CaO-Fe2O3 mixture created CaxFeyOz, which selectively reacted with N-H and C≡N, facilitating the conversion of HNCO and HCN to NH3. While temperature is a crucial factor in the performance of CaO, its impact on Fe2O3 is primarily confined to transformation of heterocyclic and nitrile. Below 350 °C, Fe2O3 favored the evolution of nitrogen into heterocyclic compounds within tar. Conversely, above 490 °C, it inhibited the formation of nitrile in char, promoting the dehydrogenation of tar into unsaturated aromatic structures. The CaO-Fe2O3 mixtures exhibited a superposition of individual effects from CaO and Fe2O3, with CaxFeyOz stimulating N2 emission. Importantly, among three conditioners, Fe2O3 showed the most significant abatement effect on NOx precursors, primarily through nitrogen fixation in char, nitrogen enrichment in tar, and precursor oxidation. This research contributes innovative perspectives on nitrogen regulation in nitrogen-rich fuels, the utilization of NH3, and effective NO and N2O control.

Structural changes and product distribution of typical Xinjiang coals and chars during pyrolysis

AbstractThis study used micro‐Raman spectroscopy, gas chromatography–mass spectrometry (GC–MS), and gas chromatography–flame ionization detector/thermal conductivity detector (GC–FID/TCD) to analyze the structure and pyrolysis reactions of nine typical coals and chars from Xinjiang. The study fitted 10 Gaussian bands of typical Xinjiang coal and investigated the changes in coal structure during coalification and pyrolysis. The results indicated that the reduction degree of CO structures in coal during coalification had a rough linear relationship with the Vdaf (dry ash‐free volatile matter) content. During coalification, the condensation of aromatic rings is accompanied by a continuous decrease of CO structures, while the contents of cross‐linking and substitution structures decrease persistently relative to the large aromatic ring structures. The influence of coal type on char yield for typical Xinjiang coal is within 15 wt.%; the influence on tar yield is within 8.5%, with a greater impact on the yield of alkanes and phenols in tar; the influence on CO yield in pyrolysis gas is within 6.3%. The relative content of large aromatic ring structures in coal is relatively stable during pyrolysis, while the relative content of small aromatic ring structures declines as coal transforms into char. The study inferred that small aromatic rings might decompose and transform into tar after pyrolysis reaction, which also resulted in a high selectivity of phenolic products in tar from most coal pyrolysis above 40%. This study revealed the structural changes and pyrolysis product distribution of nine typical coals and chars from Xinjiang, providing useful information for their utilization.

On the adsorption characteristics and mechanism of methylene blue by ball mill modified biochar

In this study, modified biochar (BRB) was prepared from rice straw by ball milling technique and used for the adsorption of methylene blue (MB) in wastewater. The BRB was characterized by SEM, FTIR and XPS, and the adsorption model and Box–Behnken design were used to optimize the five influencing factors. The results showed that the ball milling technique could increase the content of functional groups (–OH, C=C and C–O, etc.) and aromatic structures on the surface of biochar, thus facilitating the removal of MB. The isotherm model was consistent with the Langmuir adsorption model (R2 = 0.947) and the maximum adsorption capacity was 50.27 mg/g. The adsorption kinetics was consistent with the pseudo-second-order kinetic model (R2 = 1) and the adsorption rate was mainly controlled by chemisorption. The thermodynamic model confirmed that the adsorption process was a spontaneous heat absorption reaction. The maximum adsorption efficiency was 99.78% under the optimal conditions (40℃, pH 8, reaction time = 90 min, dosing amount = 0.1 mg), and the adsorption efficiency could be improved by increasing the pH and BRB dosing amount. The surface functional groups and crystal structure properties of BRB were the main determinants of adsorption, and it was clarified that physical adsorption, electrostatic attraction and π-π interaction were the main mechanisms for the adsorption of MB by BRB. The main mechanisms were clarified. Therefore, BRB is an economic, efficient and green adsorption material with good potential for the removal of dye pollutants in the aqueous environment.

Quantitative Analysis of Functional Groups in Different Metamorphic Grade Indian Coals using FTIR technique

To enhance the clean and economical feasible utilization of coal and reduce the coal or rock dynamic disaster, one should have an in-depth knowledge of coal macromolecular structures. In view of this, the chemical and physical structural properties of low to high-rank six Indian coals using Fourier transform infrared spectroscopy (FTIR) are presented. Four absorbance bands were identified in the subtracted spectrum for the functional group’s semiquantitative analysis in coal: hydroxyl, aliphatic, oxygen-containing, and aromatic structures associated with absorbance band at 3000–3600 cm-1, 2800–3000 cm-1, 1000–1800 cm-1, and 700–900 cm-1 respectively. Spectrum deconvolution technique was used to determine the FTIR structural parameters of coal samples. To investigate the structural transformation during coal metamorphism, correlations with Vitrinite reflectance (Ro) were formed. The present study will help to predict the conversion of organic groups to valuable liquids and gases from those samples. The macromolecular structure of coal could be useful to design the synthesis methods for carbon-based materials.

Evolution of aromatic structure and nanopores in shale kerogen by using in-situ HRTEM and in-situ FT-IR experiment

The evolution of kerogen molecular structure and nanopores plays critical roles in oil/gas generation and storage of shale gas. However, due to the heterogeneity and complexity of the kerogen molecule and nanopores, the precise process and evolution mechanism of kerogen molecule and nanopores remain obscure. In this study, in-situ Transmission Electron Microscope (TEM) was introduced to directly observe the evolution process of kerogen aromatic fringes and nanopores. Besides, nuclear magnetic resonance (NMR) spectroscopy and in-situ Fourier Transform Infrared (FT-IR) spectroscopy were also used to help analyze the evolution mechanism of kerogen aromatic structures. The results show that with the heating temperature increasing from 150 °C to 900 °C, the kerogen aromatic structure undergoes a three-stage evolution. In stage I (from 150 °C to 300 °C), the small sized aromatic clusters (naphthalene and 2 × 2 rings) drop off from the kerogen molecules and transform into the oil component. Their proportions in total kerogen aromatic rings decrease significantly from 49 % to 27 %. In stage II (from 300 °C to 700 °C), the aliphatic structures are converted to small sized aromatic clusters through aromatization, and the proportion of small sized aromatic clusters increases from 27 % to 38 %. In stage III, aromatic clusters undergo interconnection, resulting in the formation of significantly larger aromatic rings. During this stage, the proportion of large sized aromatic clusters increases obviously from 8 % to 42 %. Based on the in-situ HRTEM images, 2–15 nm pores were also identified. Throughout the heating process, the nanopore area within the kerogen particle (1956 nm2) exhibits an initial increase from 170 nm2 to 377 nm2 (150 °C–600 °C). Subsequently, the nanopore area experiences a decrease from 377 nm2 to 140 nm2 (600 °C–900 °C). By utilizing the benefits of in-situ HRTEM, the evolution of kerogen molecules and nanopores were elucidated in detail, aiding in the comprehension of the oil/gas generation and shale gas storage.

Selective thermal recycling for graphene growth on natural substrates: A comparative study on life cycle assessment, energy consumption, and mechanical performance in recompounding

AbstractManufacturing of carbon‐based materials from waste thermoplastics is a keystone to reduce adverse environmental impacts. There are numerous attempts for sustainable graphene manufacturing from various waste sources by thermal treatment but there is no clear distinction on the effective conversion process by addressing reliable CO2 footprints. This study provides a comprehensive benchmarking study on the conversion of waste polypropylene plastics coming from yogurt containers into graphene on the substrate of talc by applying two upcycling techniques of catalytic carbonization (CC) and flash pyrolysis (FP) by comparing energy and speed of the processes and a dimensional stability and physical characteristics of the produced graphene substances by adopting a comparative life cycle assessment. FP led to the sphericalization of graphenes due to fast dehydration, cross‐linking, and carbonization of aromatic structures. On the other hand, gradual heating in CC caused the formation of tubular‐like graphene structures. In addition, FP became advantageous by resulting in 52% of CO2 emission compared with CC process. On the other hand, graphenes separated from talcs exhibited a remarkable 70% reduction in global warming potential compared with conventional graphene production from graphite. In order to complete the value chain and circularity, the mechanical performance of two different hybrid additives produced by selective thermal recycling in recompounding with copolymer polypropylene was examined, and additives from CC enhanced the flexural and tensile properties two times better than the one from FP. With this study, it becomes possible to compare analysis of graphene growth on natural substrates by exploring life cycle assessment, energy consumption, and mechanical performance with selective thermal recycling and recompounding.

Thienothiophene-centered ladder-type π-systems that feature distinct quinoidal π-extension

Quinoidal π-conjugated structures, a kind of fundamental subunits for organic π-systems, may produce some intriguing optical, electronic and magnetic properties of polycyclic hydrocarbons (PHs). Herein, we report two thienothiophene-centered ladder-type polycyclic molecules (1 and 2), which possess one quinoidal thienothiophene moiety and two para-quinodimethane (p-QDM) subunits, respectively. As theoretically and experimentally studied, while 1 is a fully closed-shell molecule, 2 owns an open-shell structure along with partial contribution of tetraradical state that is induced by the resonance of p-QDM. Moreover, although 2 has a larger π-conjugated skeleton and open-shell electronic state, it exhibits larger bandgap and blue-shifted absorption. On the other hand, the reversible oxidation activity of 1 enables the preparation of its dication 12+, and the studies on its single-crystal and aromatic structures demonstrate that its two positive charges are delocalized onto the oxygen atoms, thus achieving fully π-extended structure and near-infrared absorption. This study not only gains insight into quinoidal π-subunits, but also provides an important basis for the development of antiaromatic and open-shell π-electron materials.

Comparison of secondary organic aerosol (SOA)-associated molecular features at urban sites in China and Korea in winter and summer (2019)

Secondary organic aerosol (SOA) formation is important in the field of atmospheric science due to its impacts on public health and climate change. However, the molecular compositions or formation mechanisms of SOA have not been fully characterized in ambient atmospheres. In this study, ambient fine particle (PM2.5) samples were collected in two urban cities in Beijing, China and Gwangju, Korea during the winter and summer seasons, and the SOA-associated molecular features were characterized by using Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). We found that the secondary organic carbon (SOC) during wintertime in Gwangju exhibit a more aliphatic nature, and those in Beijing have more aromatic structures like humic compounds. The contribution of CHOS to the total identified WSOC associated SOC was the most abundant at Beijing site (∼40%) compared to the Gwangju site (∼30%), and the proportion of CHON species in the WSOC associated SOC accounted for ∼30% in Beijing and 20–30% in Gwangju. Majority of SOC-derived CHOS species (∼99%) likely contained sulfate functional groups at both sites regardless of the sampling season. Organonitrates predominated in CHON species in summer compared to winter, but some fractions appeared to contain other potential nitrogen functional groups such as amide and nitrile (∼20%), suggesting the existence of other formation pathways of organic nitrogen, especially during winter. This work gave an observation insight into the molecular features of SOC at two different sites, and will deepen the understanding on the region-specific SOA formation mechanisms.

High-efficient co-removal of copper and zinc by modified biochar derived from tea stalk: Characteristics, adsorption behaviors, and mechanisms

Tieguanyin tea stem was used as a raw material, and potassium hydroxide (KOH), hydrochloric acid (HCl), potassium ferrate (K2FeO4), and other modifiers were used to synthesize three modified biochar (HCl-BC, KOH-BC, Fe-BCs), for competitive adsorption of copper (Cu2+) and zinc (Zn2+). Among them, Fe-BCs had the highest adsorption capacity. Fe-BC650 (K2FeO4-modified biochar heated at 650 °C) could reach adsorption equilibrium in 1 min with a high adsorption capacity. The maximum adsorption capacity of Fe-BC650 for Cu (II) and Zn (II) in the single-heavy metal solution was 303.5996 mg/g and 254.0711 mg/g, respectively. However, there were antagonistic impacts between Cu2+ and Zn2+ after analysis by the extended Langmuir model. The Brunauer-Emmett-Teller (BET) results indicated the specific surface area of Fe-BC650 was multiplied by 245 than the raw biochar (BC650), and the iron species was present in the pores of biochar through FeO bonding rather than on the surface. The results of dissolved organic carbon showed that iron species promoted the formation of aromatic structure but decreased the abundance of aromatic species in the composition. Moreover, K2FeO4 provided a large amount of K+ that could undergo cation exchange reactions with Cu2+ and Zn2+. The heavy metals became flocculent precipitate(MCO3) and deposited at the bottom of the centrifuge tube by flocculation. These characteristics constitute the excellent adsorption performance of Fe-BC650.

Methodologies for Spontaneous Preparation of Chemosensors and Their Arrays Using Off‐the‐Shelf Reagents

AbstractChemosensors offer promising candidates for visualizing molecular recognition information through colorimetric or fluorescence responses. When designing chemosensors, the following requirements should be considered: 1) molecular geometries of the analytes, 2) mechanisms that cause optical changes upon analyte capture, and 3) solubility for sensing applications. However, the designs and realization of chemosensors that meet these requirements remains a cutting‐edge challenge. Conventional strategies mainly consider the molecular geometries of the receptors and analytes. However, this approach presents the issues related to the extensive synthetic efforts required to obtain elaborate chemosensor designs, leading to decreased water solubility in chemosensors derived from complicated and aromatic molecular structures. This review summarizes the methodologies for self‐assembled chemosensors that use only off‐the‐shelf reagents, to easily obtain various chemosensors without organic synthesis. The self‐assembled chemosensors, comprising off‐the‐shelf reagents with water solubility, facilitates both easy tuning of optical sensing properties and chemical sensing in real samples. The usability of off‐the‐shelf reagents in analytical chemistry will be clarified through comprehensive sensing applications involving simple self‐assembled chemosensors and their arrays.