Organic Molecular Structure Research Articles

Impact of organic acid molecular length and structure on rock oil-wetting rapidity and stability

The oil-wetting properties of organic acids play a crucial role in various industrial applications, including enhanced oil recovery, oil spill remediation, surface modification, and so on. This study investigated the impact of organic acid molecular length and structure on oil-wetting rapidity and stability on sandstone and carbonate. Model oils prepared by dissolving organic acids in n-decane, and crude oil, were used as the oil phase. Their oil-wetting behavior was evaluated by contact angle values. The maximum molecular length of each organic acid was approximated based on its molecular structure. Our results indicate that organic acids change wettability much faster in carbonate rock than in sandstone. Longer organic acid molecules exhibit enhanced oil-wetting potential due to increased hydrophobic interactions with oil phases. Water film does not have a long-term impact on the oil-wetting process by organic acid on Indiana limestone. However, the existence of a water film largely inhibited the oil-wetting process for Indiana limestone in crude oil, and for Berea sandstone in crude and model oil. Furthermore, molecular structure, such as the presence of functional groups, significantly influences oil-wetting properties. Organic acids with an aromatic ring demonstrated a more stable oil-wetness against wettability alteration induced by surfactant treatment. Gemini surfactants with benzene ring(s) in the spacer removed aromatic organic acid more efficiently than surfactants without benzene ring. Overall, this study provides insights into the design and optimization of organic acids for applications requiring effective oil-wetting and oil-wetness stability, as well as the designing of surfactant structures with higher oil removal efficiency.

Metal-Ligand Exchange Coupling Alters the Open-Shell Ligand Electronic Structure in a Bis(semiquinone) Complex.

The electronic structure of the bis(dioxolene) bridging ligand -SQ2Th2- is responsive to metal-ligand magnetic exchange coupling. Comparison of the crystal structure of (NiSQ)2Th2 to that of (ZnSQ)2Th2 indicates an open-shell biradical ground state for the dinuclear Ni(II) complex compared to the closed-shell quinoidal character found in the dinuclear Zn(II) complex. Consistent with a comparison of bond lengths obtained by X-ray diffraction, the analysis of the variable-temperature magnetic susceptibility data for crystalline (NiSQ)2Th2 yields reduced SQ-SQ radical-radical magnetic exchange coupling (JSQ-SQ = -203 cm-1) compared to that of (ZnSQ)2Th2 (JSQ-SQ = -321 cm-1). The reduced SQ-SQ exchange coupling in (NiSQ)2Th2 derives from an attenuation of the SQ spin densities, which in turn is derived from the Ni-SQ antiferromagnetic exchange interactions. This reduction in SQ--SQ exchange that we observe for (NiSQ)2Th2 correlates with an effective lengthening of the bridge unit by ∼2.1 Å relative to that of (ZnSQ)2Th2. This magnitude of the effective increase in the bridge distance is consistent with the (NiSQ)2Th2 JSQ-SQ value lying between those of (ZnSQ)2Th2 and (ZnSQ)2Th3. The ability to modulate spin populations on an organic radical via pairwise Ni-SQ magnetic exchange interactions is a general way to affect electronic coupling in the Th-Th bridge. Our results suggest that metal-radical exchange coupling represents a powerful mechanism for tuning organic molecular electronic structure, with important implications for molecular electronics and molecular electron transport.

Feasibility of using recycled waste travertine stone powder (RWTSP) as a substitute for mineral filler in microsurfacing surface treatment

Each year, a significant amount of construction waste (CW) is produced globally, creating a major environmental challenge for its proper disposal. Utilizing recyclable CW in pavements not only helps address environmental issues but also conserves non-renewable materials. This study aims to investigate and assess the effectiveness of substituting recycled waste travertine stone powder (RWTSP) as a mineral filler (MF) in the microsurfacing surface treatment mixing plan. Initially, the physical and chemical properties of the materials used in asphalt were evaluated. The performance of the microsurfacing treatment was then examined through tests including wet cohesion, wet track abrasion, loaded wheel-displacement, and loaded wheel-sand adhesion, conducted using five different combinations (RWTSP0 +MF100, RWTSP25 +MF75, RWTSP50 +MF50, RWTSP75 +MF25, and RWTSP100 +MF0) in accordance with ISSA A143 guidelines. Additionally, FESEM-EDS, XRF, and FTIR tests were performed to assess particle shape, analyze material surface, identify constituents, determine structure, and examine organic compounds, chemical bonds, functional groups, and molecular structure. The results indicated that mixes containing RWTSP filler improved the performance of microsurfacing. This is attributed to RWTSP filler's high percentage of CaO and SiO2, as well as its more uneven and rough surfaces compared to mineral filler. For instance, in an 8% bitumen mix, the blend containing 100% RWTSP increased cohesion at 30 and 60 min by 30.8% and 30.7% respectively, improved abrasion resistance by 50%, and reduced mixture bleeding by 10.3%. Moreover, this mix enhanced resistance against vertical and lateral displacements by 32.1% and 34.4% respectively. Finally, ANOVA analysis revealed that RWTSP filler, bitumen, and material interaction were key factors influencing the performance of microsurfacing.

Machine-Learned Potentials by Active Learning from Organic Crystal Structure Prediction Landscapes.

A primary challenge in organic molecular crystal structure prediction (CSP) is accurately ranking the energies of potential structures. While high-level solid-state density functional theory (DFT) methods allow for mostly reliable discrimination of the low-energy structures, their high computational cost is problematic because of the need to evaluate tens to hundreds of thousands of trial crystal structures to fully explore typical crystal energy landscapes. Consequently, lower-cost but less accurate empirical force fields are often used, sometimes as the first stage of a hierarchical scheme involving multiple stages of increasingly accurate energy calculations. Machine-learned interatomic potentials (MLIPs), trained to reproduce the results of ab initio methods with computational costs close to those of force fields, can improve the efficiency of the CSP by reducing or eliminating the need for costly DFT calculations. Here, we investigate active learning methods for training MLIPs with CSP datasets. The combination of active learning with the well-developed sampling methods from CSP yields potentials in a highly automated workflow that are relevant over a wide range of the crystal packing space. To demonstrate these potentials, we illustrate efficiently reranking large, diverse crystal structure landscapes to near-DFT accuracy from force field-based CSP, improving the reliability of the final energy ranking. Furthermore, we demonstrate how these potentials can be extended to more accurately model structures far from lattice energy minima through additional on-the-fly training within Monte Carlo simulations.

Bacterial community regulation of soil organic matter molecular structure in heavy metal-rich mangrove sediments

Heavy metals (HMs) profoundly impact soil carbon storage potential primarily through soil carbon structure. The association between HM content and soil carbon structure in mangrove sediments remains unclear, likely due to the involvement of microorganisms. In this study, surface sediments in the Futian National Mangrove Nature Reserve were sampled to investigate the chemical structure of soil organic carbon (SOC), the molecular composition of dissolved organic matter (DOM), and potential interactions with microorganisms. HMs, except for Ni, were positively correlated with soil carbon. HMs significantly reduced the alkyl C/O-alkyl C ratio, aromaticity index, and aromatic C values, but increased the labile carboxy/amide C and carbonyl C ratio in SOC. HMs also increased DOM stability, as reflected by the reduced abundance of labile DOM (lipids and proteins) and increased proportion of stable DOM (tannins and condensed aromatics). Bacteria increased the decomposition of labile DOM components (unsaturated hydrocarbons) and the accumulation of stable DOM components (lignins) under HM enrichment. In addition, the association between the bacterial groups and DOM molecules was more robust than that with fungal groups, indicating bacteria had a more significant impact on DOM molecular composition. These findings help in understanding the molecular mechanisms of soil carbon storage in HM-rich mangroves.

Occurrence Modes of Critical Metals (Li+ and Ge4+) in the Organic Molecular Structures of Coal: A Density Functional Theory Study.

To explore the mechanism of critical metal (Li+ and Ge4+) occurrence in the organic molecular structures of different rank coals, simulations were investigated using quantum chemical density functional theory. In this paper, Wender lignite, bituminous, and anthracite molecular models were used as organic molecular structures in coal. The electrostatic potential (ESP), frontier molecular orbitals, and Mulliken charges were used to identify adsorption sites in organic molecular structures. Mulliken charge, bond length, Mayer bond order (MBO), and adsorption energy values were used to estimate the binding conformation and strength between organic molecular structures and critical metals (Li+ and Ge4+). The results showed that the negative ESP, the highest occupied molecular orbitals, and negative Mulliken charges in the organic molecular structures were located at the O atom of oxygen functional groups and the aromatic structures, respectively, which were the active sites for critical metal adsorption. Mulliken charge transfer, bond length, MBO, and adsorption energy data suggested that the binding of Li+ with organic molecular structures was controlled by the carbonyl group (C=O), while the aromatic structures had less effect on the occurrence of Li+ in the organic molecular structures. The maximum adsorption energy value for binding Li+ with organic molecular structures was -742.16 kJ/mol. The Ge4+ ions not only showed strong binding ability with oxygen functional groups, but also Ge4+ formed thermodynamically stable half-sandwich complexes with aromatic structures. Therefore, the coal rank had little effect on the binding of Ge4+ with organic molecular structures. Moreover, the binding of Ge4+ with organic molecule structures was enhanced by the synergistic interactions of oxygen functional groups and aromatic structures. The adsorption energy values were up to -8511.43 kJ/mol. The adsorption of organic matter in coal to critical metals (Li+ and Ge4+) generated changes in the spatial configuration of the organic molecular structure, including local twisting of the organic molecular structure in lignite and bending of the aromatic structure in anthracite.

Electro-controlled membrane coupling Fenton (E/M-Fenton) in treating nanofiltration concentrate: Removal performance and membrane fouling behavior

Fenton and membrane filtration are increasingly adopted as treatments to treat nanofiltration (NF) concentrates. However, dosing acid and alkali agents could pose environmental risks for the traditional Fenton. To address this challenge, the performance of traditional Fenton was investigated in NF concentrate treatment. The as-optimized conditions were Fe2+ 4 mM, H2O2 10 mM, and pH 3.5. The Fenton effectively degraded fluorescent materials, especially humic-like and fulvic-like substances. Based on these conditions, the traditional Fenton approach improved the specific ultrafiltration (UF) flux above 0.67. An increase in hydraulic shear among 0.4 ∼ 1.6 m/s and a decrease in filtration pressure between 30 ∼ 80 kPa benefited the UF reversible and irreversible fouling, respectively. The electro-controlled membrane coupling Fenton (E/M-Fenton) process was suggested by adding electrolysis, achieving the in situ production of H+ cations and OH− anions. Compared with the E/M-Fenton without internal recirculation, the porosity on the surface of the membrane was increased by 15.4% in the system with internal recirculation. Moreover, it averagely removed 66.5% of dissolved organic matter and 78.8% of UV absorbance at 254 nm, limiting the rigidity of the organic molecular structure and further improving the UF permeate. The E/M-Fenton slightly increased transmembrane pressure by 18%, performing stable UF fouling in a week. These results are essential to developing environmental-friendly strategies for Fenton to treat NF concentrate.

Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy

Elucidating the molecular structure of sedimentary organic matter (SOM) is key to understanding petroleum generation processes, as well as ancient sedimentary environments. SOM structure is primarily controlled by biogenic source material (e.g., marine vs. terrigenous), depositional conditions, and subsurface thermal history. Additional factors, e.g., strain, may also impact the molecular structure of SOM. Multiple spatially resolved approaches exist for in situ evaluation of SOM, including Raman and infrared spectroscopies, as well as mass spectrometric methods. While these methods have enabled increased understanding of the occurrence and distribution of SOM functional groups, they suffer from disadvantages including low spatial resolution (infrared spectroscopy), limited molecular information (Raman spectroscopy), and sample destruction (mass spectrometric methods). Recent technological advances have resulted in infrared spectrometers capable of breaking the Abbe diffraction limit, greatly increasing the spatial resolutions accessible for an infrared measurement.Here we utilize optical photothermal infrared spectroscopy (O-PTIR) to record maps of functional group distributions at 500 nm spatial resolution in Tasmanites (algal microfossils) from the Upper Devonian Ohio Shale. These data allow for discrimination between Tasmanites, adjacent SOM, and fine-grained minerals. Additionally, functional group distributions within Tasmanites were found to be generally homogenous, although slight variations exist between the body and fold apices (zones of greatest deformation) which may indicate strain-induced chemical reactions. The data presented here represent the first application of O-PTIR to study SOM, highlighting the promise of this analytical approach for future studies evaluating the molecular composition of geologic materials at sub-micron scales.

Resilient silica-based aerogels with organic and inorganic molecular hybrid structure prepared by a novel self-catalyzed gelling strategy for efficient heat insulation and CO2 adsorption

Silica aerogels have been attractive candidates for thermal insulation in many scenes, but they still suffer from high costs and especially brittle nature. In this work, a novel self-catalyzed gelling strategy was proposed to prepare resilient hybrid aerogels (HAs) with an organic–inorganic in-situ hybrid structure at the molecular level. Bis(trimethoxysilylpropy)amine is chosen as the single silicon source because it has alkalinity from the amine groups, high six functionality and molecular organic–inorganic hybrid nature, which help to achieve self-catalyzed gelling, high strength, and great resilience, respectively. For the as-prepared HAs, a 20 % fully recoverable strain, high Young’s modulus up to 10.40 MPa, high ultimate stress as high as 2.41 MPa and large ultimate deformation of 52 % are achieved together. Interestingly, HAs exhibit an improved modulus and strength after multiple compression, and this can increase the servicing safety in practical application. Benefiting from the synthetic effects of low density, high specific surface area and small pore size, the thermal conductivity of our aerogels is down to 18.8 mW·m−1·K−1 at ambient condition. Furthermore, the hydrophobic aerogels prepared through chlorotrimethylsilane modification also display a low thermal conductivity of 18.9 mW·m−1·K−1 at −50 °C and desirable mechanical properties at low temperatures. Unexpectedly, the rich amine groups and large specific surface area endow the fabricated aerogels with a remarkably high CO2 adsorption capacity up to 5.21 mmol/g at 273 K and excellent cyclic reusability. Considering these excellent functionalities, HAs have great prospects to serve as ideal thermal insulators, cold insulators and CO2 sorbents. The self-catalyzed gelling strategy provides an alternative route for the simple preparation of silica-based aerogels.

Characteristic of Molecular Weight-Fractions of Soil Organic Matter from Calcareous Soil and Yellow Soil

Soil organic matter (SOM), along with the rock weathering, originating from the residues of animals, plants and microorganisms involved in soil formation and evolution. The stability of SOM could directly produce an effect on carbon sequestration. To elucidate the stability characteristics of SOM in karst areas at the molecular structure level, in this study, the humic acids (HA), as the major proxy of SOM, were extracted, purified, and ultra-filtrated. The HA from calcareous soil were fractionated into five size fractions, while the HA from yellow soil were separated into eight size fractions. Via the analysis of potentiometric titration, FTIR, and CPMAS 13C NMR, the results showed some common features, whereby compared with the bigger size fractions, the smaller size fractions have much lower contents of aliphatic carbon, but have higher contents of aromatic carbon, carboxyl groups, ketonic groups, phenolic hydroxyl groups, and total acidity, which indicates that the smaller size fractions are more soluble as well as more degradable than the bigger ones. It was distinct that, in the size fractions of HA from calcareous soil, negative correlations between the acidic functional groups’ contents and the oxygen contents were found, suggesting that the oxygen was mainly located in the hydroxyl group of carbohydrates instead of carboxyl and hydroxyl groups in aromatic rings, and confirming that the bigger size fractions have much higher contents of carbohydrate subunits. According to the analysis, comparing with the HA in yellow soil, we presumed that the HA from calcareous soil were more polar and degradable. However HA from calcareous soil had a larger molecular size than that of HA from yellow soil, as well as, calcareous soil had a higher content of SOM than that of the same layer of yellow soil which suggests that the conservation mechanism of HA in calcareous is not only the organic molecular structure resistance but also the chemical protection from forming complexes with calcium or/and physical protection from enclosing by hypergene CaCO3 precipitation.

Changes in soil organic matter molecular structure after five-years mimicking climate change scenarios in a Mediterranean savannah.

Mediterranean savannahs (dehesas) are agro-sylvo-pastoral systems with a marked seasonality, with severe summer drought and favourable rainy spring and autumn. These conditions are forecasted to become more extreme due to the ongoing global climate change. Under such conditions, it is key to understand soil organic matter (SOM) dynamics at a molecular level. Here, analytical pyrolysis (Py-GC/MS) combined with chemometric statistical approaches was used for the molecular characterization of SOM in a five-years field manipulative experiment of single and combined rainfall exclusion (drought) and increased temperature (warming). The results indicate that SOM molecular composition in dehesas is mainly determined by the effect of the tree canopy. After only five years of the climatic experiment, the differences caused by the warming, drought and the combination of warming+drought forced climate scenarios became statistically significant with respect to the untreated controls, notably in the open pasture habitat. The climatic treatments mimicking foreseen climate changes affected mainly the lignocellulose dynamics, but also other SOM compounds (alkanes, fatty acids, isoprenoids and nitrogen compounds) pointing to accelerated humification processes and SOM degradation when soils are under warmer and dryer conditions. Therefore, it is expected that, in the short term, the foreseen climate change scenarios will exert changes in the Mediterranean savannah SOM molecular structure and in its dynamic.

Frontiers of molecular crystal structure prediction for pharmaceuticals and functional organic materials.

The reliability of organic molecular crystal structure prediction has improved tremendously in recent years. Crystal structure predictions for small, mostly rigid molecules are quickly becoming routine. Structure predictions for larger, highly flexible molecules are more challenging, but their crystal structures can also now be predicted with increasing rates of success. These advances are ushering in a new era where crystal structure prediction drives the experimental discovery of new solid forms. After briefly discussing the computational methods that enable successful crystal structure prediction, this perspective presents case studies from the literature that demonstrate how state-of-the-art crystal structure prediction can transform how scientists approach problems involving the organic solid state. Applications to pharmaceuticals, porous organic materials, photomechanical crystals, organic semi-conductors, and nuclear magnetic resonance crystallography are included. Finally, efforts to improve our understanding of which predicted crystal structures can actually be produced experimentally and other outstanding challenges are discussed.

A critical review of organic pollutants in Refinery wastewater by advanced oxidation processes

Advanced oxidation processes (AOPs), for instance Ozone, Fenton process, photo Fenton, photolysis, photo-catalysis, and photolysis of hydrogen peroxide and photolysis of ozone have remained inspected widely aimed at the elimination of a wide variety of organic pollutants (OPs). AOP without UV might not attain complete elimination of a comprehensive group of OPS. When combined with UV, AOPs produce additional free radicals, consequently execution improved squalor of the OPS. This review briefly deliberates the individual AOPs and their limits in the direction of the squalor of OPS comprising diverse useful collections. It too categorizes AOPs and lengthily clarifies their efficiency aimed at the squalor of a wide variety of OPS. Underneath suitable circumstances, AOPs not solitary initiate squalor nonetheless might too principal to whole mineralization. Numerous issues can affect the competence of procedures counting the chemistry of water and the organic molecular structure for instance, the attendance of organic content in water can have an important influence. In general, these organic also change toward high redox possible radicals upon crash with additional reactive species and upsurge the rates of reaction, or might performance by way of radical scavengers and reduction the development competence

Investigation on the influences of CO2 adsorption on the mechanical properties of anthracite by Brazilian splitting test

To understand CO2 sequestration in coal seam, the Brazilian splitting test is adopted to examine the effect of CO2 saturation pressure on anthracite mechanical properties, and the variations in the internal structure of coal are analyzed using X-ray diffraction and low-pressure N2 adsorption methods. The results show that as the CO2 adsorption pressure increases, the Brazilian splitting strength, Brazilian splitting modulus, absorbed energy, and Brittleness index of anthracite decrease by 11.5%–49.2%, 11.0%–44.2%, 17%–42.3%, and 6.7%–49.3%, respectively, while the BET-SSA, DFT and BJH pore volumes increase by 60.3%–225.1%, 11.6%–61.3% and 10.1%–42.7%, respectively. Moreover, the influence of supercritical CO2 on coal pore structure and mechanical property is more prominent than that of subcritical CO2. The mineral dissolution, organic matter extraction and molecular structure rearrangement caused by CO2 intrusion develop the pore structure of anthracite, which resultes in the degradation of coal mechanical properties. In addition, the swelling, plasticity, and ‘Rehbinder effect’ caused by CO2 adsorption contribute to the mechanical damage of anthracite. Due to the remarkable impact of high-pressure CO2 on the pore structure and mechanical properties of coal, the critical point pressure of CO2 should be used in the storage process to ensure enhanced CO2 storage capacity while reducing storage risks.

AIE-active asymmetric A-π-A′ molecule with mechanoluminescent property

It is of great significance to explore the inherent relationship between organic molecular structure and photoluminescence mechanism. As we known, the push-pull electron groups of organic molecules have an obvious impact on molecular charge transfer. In this work, an asymmetric A-π-A′ molecule architecture was formed by using electron-rich carbazolyl as π-spacer (π) and p-fluorobenzesulfonyl and pyridinyl as acceptor (A) chromophores. The molecule has aggregation-induced emission (AIE) and mechanoluminescent features. Notably, the switching of the excited states from the locally excited state to the twisted intramolecular charge transfer state plays important roles in the AIE properties. Based on single crystal data and DFT calculations, we found that the change of intermolecular charge transfer (CT) to intramolecular charge transfer (ICT) states is the main cause of the mechanoluminescent performance. These results indicate that the molecular structure of A-π-A′ plays an important role in AIE and mechanoluminescence.

Conjugated polymer-based luminescent probes for ratiometric detection of biomolecules.

Accurate monitoring of the biomolecular changes in biological and physiological environments is of great significance for the pathogenesis, development, diagnosis and treatment of diseases. Compared with traditional luminescent probes on the basis of an intensity-dependent single-channel readout, ratiometric fluorescence detection is a more reliable sensing or imaging method which can monitor different emission signals in two or more channels with a built-in self-calibration functionality, attracting growing attention in biomolecule detection. As a kind of luminescent material with many prospects, conjugated polymers with an easily functionalized organic molecular structure, high brightness, superior stability, tunable emission, and superior biocompatibility have been widely adopted as ratiometric fluorescent probes in biosensing and bioimaging. This review first summarizes the design principles of luminescent conjugated polymers that have been developed as methods for the ratiometric measurement of biomolecules. Additionally, their potential in accurate biodetection of living biosystems was investigated. This paper aims to provide a comprehensive review of the existing challenges and latest advancements in ratiometric detection of various biomolecules with high selectivity and sensitivity. We sincerely expect that the information presented in this review could inspire broader interests across various disciplines and stimulate more exciting achievements in biodetection for the benefit of biomedical research.

The effect of temperature and wetting–drying cycles on soil wettability: Dynamic molecular restructuring processes at the solid–water–air interface

AbstractThe impact of heat treatment and wetting–drying cycles on the wetting properties of sandy forest soils was explored. Topsoil and upper subsoil were sampled at three beech forest sites in northern Germany. The air‐dried soils were treated at 20, 40 and 80°C for 24 h, with materials treated at 20°C serving as reference. After wetting, materials were air‐dried or shock‐frozen in liquid N2 and freeze‐dried. Interfacial properties were monitored by sessile drop contact angles (CAs) and X‐ray photoelectron spectroscopy (XPS), which provide physical and chemical information on the outermost particle interface layer. CAs of reference samples were around 90° and significantly increased after 80°C‐treatment to >90°, whereas 40°C‐treatment had in comparison to reference soils no distinct impact on CA. Depending on the initial temperature treatment, air‐drying after wetting decreased CA to 60–80% and shock‐freezing and freeze‐drying decreased CA to 10–50% of the reference value. Results suggest that shock‐freezing may preserve the organic matter molecular structure that prevails during contact with water at the solid–liquid interface, thus indicating the wettability of the wet surface. Generally, wetting–drying cycles had the least impact on 80°C‐treated material. XPS analysis confirmed dynamic interfacial molecular restructuring processes by changes in O and C content and the content of non‐polar C compounds. A second heat treatment after two wetting–drying cycles again proved the distinct and pronounced impact of 80°C‐treatment on CA, especially with prior shock‐freezing and freeze‐drying. In conclusion, the findings of our study indicate a sensitive and partly reversible reorganization of the solid interfacial wetting properties. Results may conceptually be used to develop dynamic wettability models, which are needed to simulate the sensitive interplay between wettability and dynamic soil hydraulic functions at sites that are exposed to intensive and periodic moisture fluctuations.Highlights T > 40°C increased contact angle; after wetting contact angle depended on how the water was removed Shock‐freezing and freeze‐drying preserves contact angle of the wetted state Contact angle changes confirm interface molecular restructuring due to heat treatment or wetting Contact angle change goes along with changes in element content within XPS analysis depth

Electronic controlled optical activity analysis on NLO crystal; 4-Amino-5-Nitroindole using morphological, spectroscopic and theoretical tools

The organic NLO crystal for 4-Amino-5-Nitroindole was grown using slow evaporation method along with customized orthorhombic lattice formation and the crystal superiority was evaluated by recording XRD pattern. The framing of crystal structure using molecular planes was examined to find unit cell parameters. The space group (Pnam) for present organic molecular structure was assigned and the density of molecular structure in crystal geometry was measured using B3LYP/6–311++G (d,p). The electronic assisted optical activity of dielectric phase of material was tested and thereby efficiency of NLO activity was calculated. The organic composite geometry was clearly tested to find the molecular stacking and crystal density for stabilizing dielectric slabs. The mulliken charge domain displacement was traced and the parametric oscillation was studied for finding the crystal stabilization. The molecular cross-sectional scattering characteristics of base and allied bond network were studied from the vibrational analysis observation. The electrical assisted electronic process was examined for determining NLO activity to for test ultra-high frequency amplification. The CT complex was identified and it also found to be belonging to indole ring. The electronic and protonic depletion space was calculated from the result of molecular dipole moment and the static charge rigidity was acknowledged. The NBMO profile was keenly grafted and the transitional energy was measured at every consumed electronic energy bands. The vibrational circular dichroic enantiomer image at all vibrational regions was drafted and the sequential pattern of transmission and absorption was verified by obtained peak intensity.

Influence of Drainage on Peat Organic Matter: Implications for Development, Stability, and Transformation.

The agricultural use of peatlands, the stabilization of the substrate for building or road construction or for increasing the capacity of soil to support heavy machinery for industrial activities (peat and petroleum extraction), harvesting to provide peat for energy, and the growing media and initiation of chemical processes must be preceded by drainage. As a consequence of drainage, peat underwent an irreversible conversion into moorsh (secondary transformation of the peat). The object of the study was to investigate comparatively the organic matter composition and molecular structure of humic acids (HAs) in the raised bog, fen, and peat-moorsh soils developed in various compositions of botanical cover, peat-forming species, and oxic and anoxic conditions as a result of the oscillation of ground water during drainage as well as to evaluate the vulnerability of soil organic matter (SOM) to decomposition. Drainage was shown to be the principal factor causing the various chemical compositions and physicochemical properties of HAs. Large and significant differences in chemical composition of peat and the properties of HAs were found to be related to the degree of decomposition. The HAs from drained peatlands were less chemically mature. In contrast, the HAs from fen and raised bog were found to be more mature than that of the corresponding drained peatlands. The above findings showed the distinguishable structure of HAs within the soil profile created by the plant residue biodegradation and formed in both oxic and anoxic conditions. The analytical methods of thermal analysis together with the optical densities and paramagnetic behaviour are suitable and effective tools for studying structure–property relationships characterizing the origin and formation process of HAs in various environmental conditions.

Azobenzene-based derivative self-assembly: Optical limiting properties and enhancement mechanism

In order to further investigate the dependence of optical limiting properties on the molecular structures, especially the strong intermolecular effects, such as the effects of hydrogen bond, dipole-dipole interaction and the influences of their synergistic effect on the optical limiting properties, three polar D-π-A conjugated azobenzene derivatives (N1, N2 and N3) with different hydrogen-bond recognition abilities were designed and synthesized. Their molecular structure and properties were characterized and evaluated by infrared spectroscopy, thermogravimetric analysis, ultraviolet–visible spectrometry, and Z-scan technique with a Q-swithed ps Nd:YAG laser system continuum. The mechanism of optical limiting enhancement is investigated by theoretical calculation and experimental measurement based on molecular self-assembly synergistic effect of hydrogen bond and dipole-dipole interaction. The results show that the nonlinear optical properties of these polar D-π-A conjugated nonlinear optical materials were obviously affected by organic molecular structure, strong intermolecular interaction and their synergetic enhancement effect.