Hasil untuk "Organic chemistry"

Artem Fediai, Franz Symalla, Tobias Neumann et al.

In organic electronics, conductivity doping is used primarily to eliminate charge injection barriers in organic light-emitting diodes, organic photovoltaics and other electronic devices. Therefore, research on conductivity doping is primarily focused on understanding and enhancing the properties of these doped layers. In contrast, this work shifts the focus from optimizing doped layers to leveraging the doping process as a tool for investigating fundamental material properties. Specifically, the dopant is used as an "agent" to enable the measurement of three critical parameters: ionization potential (IP), electron affinity (EA), and Coulomb interaction energy (VC) - that govern dopant ionization and play central roles in organic electronic devices in general. While these parameters can be measured experimentally, conventional approaches often involve intricate or indirect methods, such as spectral deconvolution, which may introduce ambiguities or fail to represent bulk properties. Here it is shown how consolidating the experimental data and simulations on the dopant ionization fraction and doped-induced conductivity can be used to estimate the mean IP or EA of the embedded organic molecule, and VC of the embedded charge-transfer complex. These results illustrate how measuring and simulating doped materials can provide access to the fundamental design parameters of organic electronic devices

Harshan Reddy Gopidi, Alae Eddine Lakraychi, Abhishek A. Panchal et al.

The position of mobile active and inactive ions, specifically ion insertion sites, within organic crystals, significantly affects the properties of organic materials used for energy storage and ionic transport. Identifying the positions of these atom (and ion) sites in an organic crystal is difficult, especially when the element has a low X-ray scattering power, such as lithium (Li) and hydrogen, which are difficult to detect with powder X-ray diffraction (XRD) methods. First-principles calculations, exemplified by density functional theory (DFT), are very effective for confirming the relative stability of ion positions in materials. However, the lack of effective strategies to identify ion sites in these organic crystalline frameworks renders this task extremely challenging. This work presents two algorithms: (i) Efficient Location of Ion Insertion Sites from Extrema in electrostatic local potential and charge density (ELIISE), and (ii) ElectRostatic InsertioN (ERIN), which leverage charge density and electrostatic potential fields accessed from first-principles calculations, combined with the Simultaneous Ion Insertion and Evaluation (SIIE) workflow -- that inserts all ions simultaneously -- to determine ion positions in organic crystals. We demonstrate that these methods accurately reproduce known ion positions in 16 organic materials and also identify previously overlooked low-energy sites in tetralithium 2,6-naphthalenedicarboxylate (Li$_4$NDC), an organic electrode material, highlighting the importance of inserting all ions simultaneously as done in the SIIE workflow.

Sarah Marie Lößlein, Rolf Merz, Yerila Rodríguez-Martínez et al.

To understand the complex interplay of topography and surface chemistry in wetting, fundamental studies investigating both parameters are needed. Due to the sensitivity of wetting to miniscule changes in one of the parameters it is imperative to precisely control the experimental approach. A profound understanding of their influence on wetting facilitates a tailored design of surfaces with unique functionality. We present a multi-step study: The influence of surface chemistry is analyzed by determining the adsorption of volatile carbonous species (A) and by sputter deposition of metallic copper and copper oxides on flat copper substrates (B). A precise surface topography is created by laser processing. Isotropic topography is created by ps laser processing (C), and hierarchical anisotropic line patterns are produced by direct laser interference patterning (DLIP) with different pulse durations (D). Our results reveal that the long-term wetting response of polished copper surfaces stabilizes with time despite ongoing accumulation of hydrocarbons and is dominated by this adsorption layer over the oxide state of the substrate (Cu, CuO, Cu2O). The surfaces' wetting response can be precisely tuned by tailoring the topography via laser processing. The sub-pattern morphology of primary line-like patterns showed great impact on the static contact angle, wetting anisotropy, and water adhesion. An increased roughness inside the pattern valleys combined with a minor roughness on the peaks favors air-inclusions, isotropic hydrophobicity, and low water adhesion. Increasing the aspect ratio showed to enhance air-inclusions and hydrophobicity despite increased peak roughness while time dependent wetting transitions were observed.

P. Nazari

Complex organic molecules (COMs) have been detected abundantly at various stages of star formation, particularly in the warm protostellar phase. The progress in gas-phase measurements has been accelerated by the advent of the Atacama Large Millimeter/submillimeter Array and in ice measurements by the James Webb Space Telescope. Particularly, the community has moved from single-source studies of COMs to statistical analyses because of these powerful instruments. In this article, I review surveys that consider COMs in the gas and ice. The two takeaways from this review include; 1. Gas-phase abundance ratios for some COMs show a small difference across many objects and the ice abundance ratios show similar or higher values to the gas, both pointing to the importance of ice chemistry in COM formation, 2. Some COM ratios show larger differences across many objects which could be due to either chemical or physical effects, thus both factors need to be considered when interpreting the data.

Aidan Pellow-Jarman, Shane McFarthing, Doo Hyung Kang et al.

A novel hybrid quantum-classical approach has been developed to efficiently address the multireference quantum chemistry problem. The Handover Iterative Variational Quantum Eigensolver (HiVQE) is designed to accurately estimate ground-state wavefunctions by leveraging both quantum and classical computing resources. In this framework, noisy intermediate-scale quantum (NISQ) hardwares efficiently explore electron configurations, while classical computers compute the corresponding wavefunction without the effect of noise of NISQ computer, ensuring both accuracy and computational efficiency. By generating compact yet chemically accurate wavefunctions, HiVQE advances quantum chemistry simulations and facilitates the discovery of novel materials. This approach demonstrates significant potential for overcoming the limitations of classical methods in strongly correlated electronic systems.

Nikolay V. Golubev, Mohammed Th. Hassan

How quantum electron and nuclei motions affect biomolecular chemical reactions remains a central challengeable question at the interface of quantum chemistry and biology. Ultrafast charge migration in deoxyribonucleic acid (DNA) has long been hypothesized to play a critical role in photochemistry, genome stability, and long-range biomolecular signaling, however, direct real-time observation of these electronic processes has remained elusive. Here, we present a theoretical investigation and propose the concept of future experimental measurements of laser-driven charge dynamics in the canonical DNA nucleobase pairs thymine_adenine and cytosine_guanine. Attosecond-resolved simulations employing high-level ab initio methods reveal base-dependent ionization mechanisms, directional charge migration pathways, and electronic coherences that govern sub-femtosecond redistribution of electron density across hydrogen-bonded nucleobase interfaces. Accordingly, we propose the concept of a quantum attosecond scanning electron microscope, termed the quantum attomicroscope (Q-attomicroscope), a capable of imaging photoinduced quantum chemistry reactions in attosecond temporal resolution and sub-nanometer spatial precision. As a proof of principle, we propose to image the charge migrations dynamics in DNA which we studied theoretically. Together, our preceptive bridges theory, instrumentation, and control, outlining a pathway toward laser mediated manipulation of DNA structure with implications for repair processes, chemical reactivity, and future personalized medicine.

Iram Pervaiz, Syed Muhammad Ahmed Rahim, Muhammad Zubair Ahmad Khan et al.

Background: Trismus or lockjaw characterized by limited mouth opening presents as complication associated with odontogenic infections commonly involving mandibular teeth. Due to limited literature providing insight to probable odontogenic causes of trismus, this study is oriented to determine the incidence of Trismus severity in association with fascial space infection resulting from odontogenic causes, i.e., pericoronitis, pulp infection, or periodontal infection. Methods: This study was conducted at the Department of Oral and Maxillofacial Surgery, Azra Naheed Dental College/ Chaudhry Muhammad Akram Dental Hospital from July 2024 to December 2024. In this descriptive cross-sectional study, following non-probability purposive sampling, 87 patients who had trismus secondary to fascial space infections were enrolled. All required demographic and clinical data were recorded in a purpose-designed form. The collected data were analyzed by the Chi-square test, using SPSS version 25. A p-value of ≤ 0.005 was considered significant. Results: The average mean value of Trismus was 23.5±5.5mm. Submandibular space infection most frequently involved the fascial space 42 (48.2%), and the mandibular third molar was frequently involved, offending tooth 43 (49.4%) in this study. The most common cause of odontogenic infection was Pulp infection/caries 58 (66.6%), followed by pericoronitis 27 (31.3%) and periodontal infection 2 (2.3%). Conclusion: Mandibular third molars are the most involved teeth, leading to fascial space infection and associated with increased severity of Trismus. The submandibular space is the most affected fascial space, and pulp infection is the major cause of odontogenic infection, leading to fascial space involvement.

Patryk Drejka, Patrycja Kula, Izabela Barszczewska-Rybarek

Six novel urethane-dimethacrylates with quaternary ammonium groups (QAUDMAs) were successfully synthesized from 2-(methacryloyloxy)ethyl-2-hydroxyethylmethylalkylammonium bromide (QAHAMA-n, where n was 8 and 10) and diisocyanate (isophorone diisocyanate (IPDI), 4,4′-methylenedicyclohexyl diisocyanate (CHMDI), and 4,4′-diphenylmethane diisocyanate (MDI)). Their chemical structures were confirmed through nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The refractive index (RI) and density (d_m) were also determined. The novel QAUDMAs were compounded with common dental dimethacrylates and subsequently photopolymerized. The resulting copolymers, comprising QAUDMA 40 wt.%, bisphenol A glycerolate dimethacrylate (Bis-GMA) 40 wt.%, and triethylene glycol dimethacrylate (TEGDMA) 20 wt.%, were tested for water sorption (WS) and solubility (SL). The WS and SL values decreased following these orderings based on the diisocyanate: IPDI > CHMDI > MDI for WS, and MDI > CHMDI > IPDI for SL. The WS values ranged from 11.50 to 13.82 µg/mm³, and were significantly lower than the recommended maximum for dental materials, 40 µg/mm³. The SL values that met the recommended maximum, 7.5 µg/mm³, ranged from 2.67 to 6.75 µg/mm³. Only the copolymer having the QAHAMA-8- and MDI-derived QAUDMA had the SL slightly exceeding 7.5 µg/mm³, at 7.89 µg/mm³.

Haochen Zhao, Xiangru Tang, Ziran Yang et al.

The advancement and extensive application of large language models (LLMs) have been remarkable, including their use in scientific research assistance. However, these models often generate scientifically incorrect or unsafe responses, and in some cases, they may encourage users to engage in dangerous behavior. To address this issue in the field of chemistry, we introduce ChemSafetyBench, a benchmark designed to evaluate the accuracy and safety of LLM responses. ChemSafetyBench encompasses three key tasks: querying chemical properties, assessing the legality of chemical uses, and describing synthesis methods, each requiring increasingly deeper chemical knowledge. Our dataset has more than 30K samples across various chemical materials. We incorporate handcrafted templates and advanced jailbreaking scenarios to enhance task diversity. Our automated evaluation framework thoroughly assesses the safety, accuracy, and appropriateness of LLM responses. Extensive experiments with state-of-the-art LLMs reveal notable strengths and critical vulnerabilities, underscoring the need for robust safety measures. ChemSafetyBench aims to be a pivotal tool in developing safer AI technologies in chemistry. Our code and dataset are available at https://github.com/HaochenZhao/SafeAgent4Chem. Warning: this paper contains discussions on the synthesis of controlled chemicals using AI models.

Mikuláš Matoušek, Nam Vu, Niranjan Govind et al.

The emerging field of polaritonic chemistry explores the behavior of molecules under strong coupling with cavity modes. Despite recent developments in ab initio polaritonic methods for simulating polaritonic chemistry under electronic strong coupling, their capabilities are limited, especially in cases where the molecule also features strong electronic correlation. To bridge this gap, we have developed a novel method for cavity QED calculations utilizing the Density Matrix Renormalization Group (DMRG) algorithm in conjunction with the Pauli-Fierz Hamiltonian. Our approach is applied to investigate the effect of the cavity on the S0 -S1 transition of n-oligoacenes, with n ranging from 2 to 5, encompassing 22 fully correlated π orbitals in the largest pentacene molecule. Our findings indicate that the influence of the cavity intensifies with larger acenes. Additionally, we demonstrate that, unlike the full determinantal representation, DMRG efficiently optimizes and eliminates excess photonic degrees of freedom, resulting in an asymptotically constant computational cost as the photonic basis increases.

Artur Stepniak, Marta Biernacka, Magdalena Malecka et al.

The aim of the research was to investigate and compare the interaction between flavanones (flavanone, 4-chloro-flavanone) with potential anticancer activity and selected cyclodextrins. Measurements were made using calorimetric (ITC, DSC) and spectrophotometric (UV-Vis spectroscopy, FT-IR, ¹H NMR) methods. The increase in the solubility in aqueous medium caused by the complexation process was determined by the Higuchi-Connors method. As a result of the study, the stoichiometry and thermodynamics of the complexation reaction were determined. The formation of stable inclusion complexes at a 1:1 M ratio between flavanone and 4-chloroflavanone and the cyclodextrins selected for research was also confirmed.

A. S. Idan, M. I. Hamzah, M. S. Khudhair

Fetuin-A, a plasma glycoprotein, has been demonstrated to play an essential role in the pathogene­sis of several metabolic disorders. This study aimed to estimate fetuin-A serum level in patients with newly diagnosed primary hyperthyroidism (PHT) and subclinical hypothyroidism (SCH) and to examine its correlation with thyroid hormones level, age and sex of patients. The study involved 90 patients with untreated thyroid dysfunction verified with thyroid function test (45 with PHT and 45 with SCH) and 90 control subjects. Triiodo­thyronin (T3), tetraiodothyronin (T4), and thyroid stimulating hormone (TSH) serum concentrations were measured with enzyme-linked fluorescent assay (ELFA), fetuin-A concentration was measured with enzyme-linked immunosorbent assay (ELISA). It was demonstrated that the level of fetuin-A was significantly higher in the PHT group as compared with the control group and showed a significant positive correlation with the T3 level. In the SCH group, the level of fetuin-A was significantly lower and showed a negative correlation with TSH level. Fetuin-A level rose with age in the PHT group and was unaffected by sex in all studied groups. The perfect AUC value obtained for fetuin-A in the comparison between PHT and SCH groups suggests its potential use as a reliable diagnostic marker to differentiate between these two thyroid conditions.

Bin Zhang, Zhigang Shuai

We present a quantum dynamic study on organic lasing phenomena, which is a challenging issue in organic optoelectronics. Previously, phenomenological method has achieved success in describing experimental observation. However, it cannot directly bridge the laser threshold with molecular electronic structure parameters and cavity parameters. Quantum dynamics method for describing organic lasing and obtaining laser threshold is highly expected. In this Letter, we first propose a microscopic model suitable for describing the lasing dynamics of organic molecular system and we apply the time-dependent wave-packet diffusion (TDWPD) to reveal the microscopic quantum dynamical process for the optical pumped lasing behavior. Lasing threshold is obtained from the onset of output as a function of optical input pumping. We predict that the lasing threshold has an optimal value as function of the cavity volume and depends linearly on the intracavity photon leakage rate. The structure-property relationships between molecular electronic structure parameters (including the energy of molecular excited state, the transition dipole and the organization energy) and the laser threshold obtained through numerical calculations are in qualitative agreement the experimental results, which also confirms the reliability of our approach. This work is beneficial to understanding the mechanism of organic laser and optimizing the design of organic laser materials. TOC

Renato P. dos Santos

This study explores the potential of Generative AI chatbots (GenAIbots) such as ChatGPT and Bing Chat, in Chemistry education, within a constructionist theoretical framework. A single-case study methodology was used to analyse extensive interaction logs between students and both AI systems in simulated Chemistry learning experiences. The results highlight the ability of ChatGPT and Bing Chat to act as 'agents-to-think-with', fostering critical thinking, problem-solving, concept comprehension, creativity, and personalised learning experiences. By employing a Socratic-like questioning approach, GenAIbots nurture students' curiosity and promote active learning. The study emphasises the significance of prompt crafting, a technique to elicit desired responses from GenAIbots, fostering iterative reflections and interactions. It underlines the need for comprehensive educator training to effectively integrate these tools into classrooms. The study concludes that while ChatGPT and Bing Chat as agents-to-think-with offer promising avenues to revolutionise STEM education through a constructionist lens, fostering a more interactive, inclusive learning environment and promoting deeper comprehension and critical thinking in students across diverse Chemistry topics, ChatGPT consistently outperformed Bing Chat, providing more comprehensive, detailed, and accurate responses and skillfully addressing nuances and context.

Kan Tang, Megan R. Brown, Chad Risko et al.

2,2’-Bis(4-dimethylaminophenyl)- and 2,2'-dicyclohexyl-1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[d]imidazole ((N-DMBI)2 and (Cyc-DMBI)2) are quite strong reductants with effective potentials of ca. −2 V vs ferrocenium/ferrocene, yet are relatively stable to air due to the coupling of redox and bond-breaking processes. Here, we examine their use in accomplishing electron transfer-induced bond-cleavage reactions, specifically dehalogenations. The dimers reduce halides that have reduction potentials less cathodic than ca. −2 V vs ferrocenium/ferrocene, especially under UV photoexcitation (using a 365 nm LED). In the case of benzyl halides, the products are bibenzyl derivatives, whereas aryl halides are reduced to the corresponding arenes. The potentials of the halides that can be reduced in this way, quantum-chemical calculations, and steady-state and transient absorption spectroscopy suggest that UV irradiation accelerates the reactions via cleavage of the dimers to the corresponding radical monomers.

Jun-ichi Morishige, Kazuaki Yoshioka, Hiroki Nakata et al.

Sphingosine 1-phosphate (S1P) has been implicated in brown adipose tissue (BAT) formation and energy consumption; however, the mechanistic role of sphingolipids, including S1P, in BAT remains unclear. Here, we showed that, in mice, BAT activation by cold exposure upregulated mRNA and protein expression of the S1P-synthesizing enzyme sphingosine kinase 1 (SphK1) and S1P production in BAT. Treatment of wild-type brown adipocytes with exogenous S1P or S1P receptor subtype-selective agonists stimulated triglyceride (TG) breakdown only marginally, compared with noradrenaline. However, genetic deletion of Sphk1 resulted in hypothermia and diminished body weight loss upon cold exposure, suggesting that SphK1 is involved in thermogenesis through mechanisms different from receptor-mediated, extracellular action of S1P. In BAT of wild-type mice, SphK1 was localized largely in the lysosomes of brown adipocytes. In the brown adipocytes of Sphk1−/− mice, the number of lysosomes was reduced and lysosomal function, including proteolytic activity, acid esterase activity, and motility, was impaired. Concordantly, nuclear translocation of transcription factor EB, a master transcriptional regulator of lysosome biogenesis, was reduced, leading to decreased mRNA expression of the lysosome-related genes in Sphk1−/− BAT. Moreover, BAT of Sphk1−/− mice showed greater TG accumulation with dominant larger lipid droplets in brown adipocytes. Inhibition of lysosomes with chloroquine resulted in a less extent of triglyceride accumulation in Sphk1−/− brown adipocytes compared with wild-type brown adipocytes, suggesting a reduced lysosome-mediated TG breakdown in Sphk1−/− mice. Our results indicate a novel role of SphK1 in lysosomal integrity, which is required for TG breakdown and thermogenesis in BAT.

Najla Grioui, Amal Elleuch, Kamel Halouani et al.

In this study, exhausted olive pomace (EOP) biochar prepared by carbonization at 400 °C is investigated as a fuel in a direct carbon fuel cell (DCFC) with an electrolyte-supported configuration. The feasibility of using the EOP biochar in the DCFC is confirmed, showing a maximum power density of 10 mW·cm⁻² at 700 °C. This limited DCFC performance is compared with other biochars prepared under similar conditions and interrelated with various biochar physico-chemical characteristics, as well as their impact on the DCFC’s chemical and electrochemical reaction mechanisms. A high ash content (21.55%) and a low volatile matter (40.62%) content of the EOP biochar are among the main causes of the DCFC’s limited output. Silica is the major impurity in the EOP biochar ash, which explains the limited cell performance as it causes low reactivity and limited electrical conductivity because of its non-crystal structure. The relatively poor DCFC performance when fueled by the EOP biochar can be overcome by further pre- and post-treatment of this renewable fuel.

Wenxiong Wu, Pan Wang

Neuropathy target esterase (NTE) is a serine hydrolase with phospholipase B activity, which is involved in maintaining the homeostasis of phospholipids. It can be inhibited by aging inhibitors such as some organophosphorus (OP) compounds, which leads to delayed neurotoxicity with distal degeneration of axons. However, the detailed binding conformation of aging and non-aging inhibitors with NTE is not known. In this study, new computational models were constructed by using MODELLER 10.3 and AlphaFold2 to further investigate the inhibition mechanism of aging and non-aging compounds using molecular docking. The results show that the non-aging compounds bind the hydrophobic pocket much deeper than aging compounds and form the hydrophobic interaction with Phe1066. Therefore, the unique binding conformation of non-aging compounds may prevent the aging reaction. These important differences of the binding conformations of aging and non-aging inhibitors with NTE may help explain their different inhibition mechanism and the protection of non-aging NTE inhibitors against delayed neuropathy.

Inga Kwiecień, Natalizia Miceli, Manuela D’Arrigo et al.

Studies carried out using three different in vitro assays and a biological setting (<i>Escherichia coil</i>) demonstrated the antioxidant activity of <i>Scutellaria lateriflora</i> microshoot extract. Moreover, the extract exhibited no toxicity in a brine shrimp lethality bioassay. These results indicated that microshoots are a rich, safe source of antioxidants, which encouraged us to enhance their production in vitro. In agar and agitated cultures, two biotechnological strategies were applied: feeding the cultures with the biogenetic precursors of the phenolics—phenylalanine and tyrosine, and eliciting them with methyl jasmonate. Specific <i>Scutellaria</i> flavonoids and verbascoside were analysed by HPLC. Feeding with precursors (1 g/L) in agar cultures decreased the production of the metabolites. In agitated cultures, different concentrations of precursors (1.0–2.5 g/L) and the elicitor (10; 50; 100 µM) were tested. Additionally, parallel feeding with the precursor and elicitor in a concentration of 50 µM were applied. The best strategy for total flavonoid and verbascoside production was phenylalanine feeding (1.5 g/L), max. 3765 and 475 mg/100 g DW, respectively, after 7 days. This is the first report documenting the high antioxidant production in <i>S. lateriflora</i> microshoots after feeding with phenylalanine. Moreover, for the first time, bioreactor cultures were successfully maintained, obtaining attractive results (max. total flavonoid content 2348 and verbascoside 485 mg/100 g DW).

R. Matthias Geilhufe

Metal organic frameworks are porous materials composed of metal ions or clusters coordinated by organic molecules. As a response to applied uniaxial pressure, molecules of straight shape in the framework start to buckle. Under sufficiently low temperatures, this buckling is of quantum nature, described by a superposition of degenerate buckling states. Buckling states of adjacent molecules couple in a transverse Ising type behavior. On the example of the metal organic framework topology MOF-5 we derive the phase diagram under applied strain, showing a normal, a parabuckling, and a ferrobuckling phase. At zero temperature, quantum phase transitions between the three phases can be induced by strain. This novel type of order opens a new path towards strain induced quantum phases.