Periodic Table Research Articles

Diels-Alder Cycloaddition of Cyclopentadiene to C60 and Si60 and Their Endohedral Li+ Counterparts.

Both silicon and carbon are elements located in group 14 on the periodic table. Despite some similarities between these two elements, differences in reactivity are important, and whereas carbon is a central element in all known forms of life, silicon is barely found in biological systems. Here, we investigate the Diels-Alder cycloaddition reaction of cyclopentadiene (CP) and cyclopentasildiene (CPSi) with fullerenes C60, Li+@C60, Si60, and Li+@Si60 using density functional theory methods. The results reveal distinct kinetic and thermodynamic trends that govern the reactivity and selectivity. For C60, the [6,6] pathway is kinetically and thermodynamically favored, whereas for Si60, the [5,6] pathway is preferred thermodynamically but not kinetically. The introduction of lithium cations increases the reactivity of both C60 and Si60. Energy decomposition analysis (EDA) unveils the importance of the components of the interaction energy between CPSi and the corresponding fullerenes. The findings provide insights into the interplay of electronic structure, substrate reactivity, and fullerene electrophilicity in cycloaddition reactions.

Pesticides’ Cornea Permeability—How Serious Is This Problem?

Background: A total of 348 pesticides from different chemical families (carbamates, organochlorines organophosphorus compounds, pyrethroids, triazines and miscellaneous) were investigated in the context of their cornea permeability and potential to cause eye corrosion. Methods: Multivariate models of cornea permeability based on compounds whose cornea permeability has been determined experimentally were proposed. The models, applicable to compounds across a relatively broad lipophilicity range (e.g., pesticides with octanol–water partition coefficient log P up to ca. 8), assume a reverse-parabolic relationship between cornea permeability and lipophilicity, expressed as XLOGP3; other main descriptors present in the models are log D at pH 7.4 and polar surface area (PSA). Results: It appears that the trans-corneal transport of all studied pesticides is possible to some degree; however, it is more difficult for the majority of highly lipophilic pesticides from the organochlorine and pyrethroid families. The same set of 348 pesticides was also evaluated for their eye-corrosive potential using novel artificial neural network models involving simple physico-chemical properties of the compounds (lipophilicity, aqueous solubility, polar surface area, H-bond donor and acceptor count and the count of atoms such as N, NH, O, P, S and halogens). Conclusions: It was concluded that eye corrosion is an issue, especially among the pesticides from organochlorine and organophosphorus families.

Synthesis of Xenes: physical and chemical methods.

Since the debut of silicene in the experimental stage more than a decade ago, the family of two-dimensional elementary layers beyond graphene, called Xenes or transgraphenes, has rapidly expanded to include elements from groups II to VI of the periodic table. This expansion has opened pathways for the engineering of elementary monolayers that are inherently different from their bulk counterparts in terms of fundamental physical properties. Common guidelines for synthesizing Xenes can be categorized into well-defined methodological approaches. On the one hand, bottom-up methods, such as physical epitaxial methods, enable the growth of monolayers, multilayers, and heterostructured Xenes. On the other hand, top-down chemical methods, including topotactic deintercalation and liquid-phase exfoliation, are gaining prominence due to the possibility of massive production. This review provides an extensive view of the currently available synthesis routes for Xenes, highlighting the full range of Xenes reported to date, along with the most relevant identification techniques.

Bonding Features of Period 3 and Period 1 Two-Dimensional Superatoms.

Despite being studied for almost two centuries, aromaticity has always been a controversial concept. We previously proposed a unified aromatic rule for π-conjugated systems by two-dimensional (2D) superatomic-molecule theory, where benzenoid rings are treated as period 2 2D superatoms (3π-◊N, 4π-◊O, 5π-◊F, 6π-◊Ne) and, further, bond to form 2D superatomic molecules. Herein, to build a 2D periodic table, we further extend the theory to period 3 (7π-◊P, 8π-◊S, 9π-◊Cl, 10π-◊Ar) and period 1 (1π-◊H, 2π-◊He) elements. Various polycyclic π-conjugated species, namely, C18H16, C14H12, C18H14, [C21H15]-, and C2B4H4, are treated as ◊Cl2, ◊Cl◊F, ◊S◊F2, ◊P◊F3, and ◊H2 superatomic molecules, respectively, where each 2D superatom achieves π electronic shell-closure via superatomic lone pairs and/or two supercenter-two electron (2sc-2e) bonds. Due to the special π electron arrangement and small superatomic orbital energy gaps, period 3 superatoms engage in novel DD, PD orbital interactions and PD, SD2 hybridizations. This work replenishes the 2D periodic table and their bonding rules.

Contamination levels and distribution of persistent and non-persistent pollutants in paired hair, urine and serum samples from a Belgian non-occupationally exposed population

ABSTRACT Designing ideal human biomonitoring studies involves the selection of reliable markers of exposure in adequate biological matrix. Besides conventional matrices such as blood or urine, hair has been increasingly investigated as a promising noninvasive alternative. However, understanding the pollutant distribution between differing biological compartments is essential for reliable interpretation of data collected. Therefore, the contamination levels and the distribution of some persistent (8 perfluoroalkyl substances – PFAS – and 6 polychlorobiphenyls – PCBs) and non-persistent pollutants (2 bisphenols and 3 parabens) were investigated in paired serum and hair samples, or paired spot urine and hair samples obtained from 30 Belgian non-occupationally exposed individuals. The levels measured were close to those reported in recent larger-scale studies. PFAS, PCB and bisphenol distributions largely differed depending upon the matrix and within the same chemical family depending upon the congener. The correlation and agreement between pollutant levels in differing matrices demonstrated that the information provided is comparable only for highly chlorinated PCBs and parabens, while the classification of exposure for bisphenols was substantially different according to the matrix. The selection of the human matrix thus remains complex and might markedly bias the results obtained, especially when assessing the health risk related to chemical exposure.

A generative model for inorganic materials design.

The design of functional materials with desired properties is essential in driving technological advances in areas like energy storage, catalysis, and carbon capture1-3. Generative models provide a new paradigm for materials design by directly generating novel materials given desired property constraints, but current methods have low success rate in proposing stable crystals or can only satisfy a limited set of property constraints 4-11. Here, we present MatterGen, a model that generates stable, diverse inorganic materials across the periodic table and can further be fine-tuned to steer the generation towards a broad range of property constraints. Compared to prior generative models 4,12, structures produced by MatterGen are more than twice as likely to be novel and stable, and more than 10 times closer to the local energy minimum. After fine-tuning, MatterGen successfully generates stable, novel materials with desired chemistry, symmetry, as well as mechanical, electronic and magnetic properties. As a proof of concept, we synthesize one of the generated structures and measure its property value to be within 20 % of our target. We believe that the quality of generated materials and the breadth of MatterGen's capabilities represent a major advancement towards creating a foundational generative model for materials design.

Upgrade of Weak σ-Hole Bond Donors via Cr(CO)3 Complexation.

Molecular recognition mediated by σ-hole interactions is enhanced as the electrostatic potential at the σ-hole becomes increasingly positive. Traditional methods to strengthen σ-hole donor ability of atoms such as halogens often involve covalent modifications, such as, introducing electron-withdrawing substituents (neutral or positively charged) or electrochemical oxidation. Metal coordination, a relatively underexplored approach, offers a promising alternative. In this study, η6-coordination of Cr(CO)3 to haloarenes, a neutral system, is demonstrated to significantly increase the electrophilic character of halogen bond donors, enabling weak donors such as chloroanisole to form short and directional Cl⋅⋅⋅O halogen bonds. Structural characterization using single-crystal X-ray diffraction and computational analysis of a series of η6-Cr(CO)3-coordinated haloarenes provides evidence for this enhancement. Furthermore, the effect is shown to extend to other heteroatomic substituents on the coordinated arene, e. g., other halogen atoms as well as elements of groups 16, 15, and 14 of the periodic table, broadening the scope of this approach.

Tetrahedral Al20O30 Cage: A Superchalcogen Atom.

Superatoms are stable clusters that mimic the chemical behavior of individual atoms in the periodic table. Many endeavors have been devoted to the design and characterization of various superatoms, while engineering superatoms to mimic the chemistry of chalcogens remains a challenge. In this paper, we present a new superchalcogen by evaluating a hollow tetrahedral Al20O30 cluster with theoretical calculations. By comparing the Al20O30 with its daughter dianion (Al20O30)2- in terms of stability, aromaticity, electronic properties, and chemical behavior in compounds, we find that this cluster tends to get two additional electrons to reach a more stable electronic state, which is the origin of the identity of superchalcogens. The adaptive natural density partitioning (AdNDP) analysis illustrates that this Al20O30 cluster accommodates two electrons by a 4-center-2-electron bond formed between the four face-centered Al atoms. Moreover, the Al20O30 cluster has exothermic first and second adiabatic electron affinity (EA), indicating that the dianion (Al20O30)2- is stable against spontaneous electron emission and fragmentation in the gas phase. This reflects the size advantage of superchalcogens when compared with chalcogens. Interestingly, we further study a cluster with one more electron than the superchalcogen Al20O30, namely, H@(Al20O30) and find that it is a superhalogen due to its large vertical and adiabatic EA.

Polarization Upends Convention: Halogen Bonding Propensities of Main Group Halides.

The propensities for sigma hole bonding by halogen atoms bonded to central atoms below period 2 in the periodic table remain to be systematically examined. Using iodine as our reference halogen atom, a comprehensive analysis of the tendencies for halogen and other forms of significant sigma hole bonding by simple compounds of main group atoms from H to At is accomplished. An examination of the structure and bonding of complexes formed by those iodine-substituted main group compounds and sigma donating bases (ammonia and trimethylamine) is performed to probe the viability of halogen bonding by heavy main group RnM-I compounds in particular, given the historic focus on period 2. We show that propensities for halogen bonding by FnM-I systems for certain columns of the main group vary anomalously as M gets heavier due to a polarization-induced escalation of the electrostatic potential on I. In certain cases, the positive potential at the sigma hole on I is weaker than that at sigma holes on the central M or geminal R atoms. Previously unexplored cases of strong halogen bonding by the fluoroiodides of heavy group 13 atoms are identified, and prospects for other sigma hole type interactions to polarized (main group) central atoms are elucidated.

Enhancing Ω Phase Thermal Stability in Al Alloys through Interstitial Ordering.

Scandium (Sc) can orderly occupy interstitial sites within the Ω phase of aluminum alloys, forming a new phase that significantly enhances the thermal stability of the alloy. However, Sc is relatively expensive and rare. In this work, we employ first-principles calculations to delve into the physical essence interstitial ordering of Sc in enhancing thermal stability at the electronic level, thereby revealing the crucial factors responsible for this improvement. By computationally screening all potential metallic elements across the periodic table, we uncover that, in addition to Sc, a diverse range of elements including lithium (Li), calcium (Ca), strontium (Sr), and some of rare earth elements (Sm, Ce, Y), possess the potential to contribute to thermal stability enhancement through interstitial ordering mechanisms in aluminum alloys. This study deepens our understanding of microstructural thermal stability and offers novel strategies for designing improved thermally stable Al alloys.

Enhancing Ω Phase Thermal Stability in Al Alloys through Interstitial Ordering.

Scandium (Sc) can orderly occupy interstitial sites within the Ω phase of aluminum alloys, forming a new phase that significantly enhances the thermal stability of the alloy. However, Sc is relatively expensive and rare. In this work, we employ first-principles calculations to delve into the physical essence interstitial ordering of Sc in enhancing thermal stability at the electronic level, thereby revealing the crucial factors responsible for this improvement. By computationally screening all potential metallic elements across the periodic table, we uncover that, in addition to Sc, a diverse range of elements including lithium (Li), calcium (Ca), strontium (Sr), and some of rare earth elements (Sm, Ce, Y), possess the potential to contribute to thermal stability enhancement through interstitial ordering mechanisms in aluminum alloys. This study deepens our understanding of microstructural thermal stability and offers novel strategies for designing improved thermally stable Al alloys.

Analytical Differentiation of Wines from Three Terroirs Located in a Warm Winegrowing Area Based on Their Volatilome.

This research aims to identify aroma compounds, their combinations, and statistical relationships to classify and characterize wines produced in small, defined areas known as "terroirs", which share edaphoclimatic characteristics grape varieties, viticultural practices, harvest timing, and winemaking processes. The goal is to deepen the understanding of the relationship between the terroir and wine typicity. This study analyzed the contents based on enological parameters, the major and minor volatile compounds of the young wines produced in three wineries across two vintages, using the Pedro Ximenez white grape variety cultivated in different terroirs within the same quality zone. Statistical tools, such as Multiple Variable Analysis (MVA) and Principal Component Analysis (PCA), were employed to identify significant differences in the volatilomes of wines. PCA effectively differentiated wines from each terroir and vintage using scores from the first two principal components, calculated based on the absolute concentrations of 12 major volatile compounds and 3 polyols. Conversely, PCA based on the concentrations of 52 minor volatile compounds showed a strong ability to classify wines by vintage year. The minor volatile contents of wines from 2 vintages, grouped into 9 chemical families, provide distinct fingerprints that enable wines to be distinguished by terroir. The results underscore the chemical basis underlying terroir typicity in a production zone within a warm Protected Denomination of Origin (PDO).

Marine actinobacteria metabolites: unlocking new treatments for acne vulgaris.

Marine-derived actinobacteria isolated from sponge Cliona varians and soft coral Eunicea fusca were screened for antibacterial activity against acne-related bacteria, specifically Staphylococcus epidermidis ATCC 14990, methicillin-resistant Staphylococcus aureus ATCC BAA44, and Cutibacterium acnes ATCC 6919. Cytotoxicity assays were performed on human dermal fibroblast (HDFa) and keratinocyte (HaCaT) cell lines to assess the safety profile of the extracts. Chemical characterization was conducted using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). Among the extracts, six derived from Kocuria sp., Rhodococcus sp., Nocardia sp., Micrococcus sp., and Streptomyces sp. demonstrated significant antibacterial activity. Notably, extract Z9.216 from Kocuria sp. exhibited the highest efficacy, inhibiting S. epidermidis by 68%, S. aureus by 93%, and C. acnes by 98.7% at a concentration of 0.003 mg/mL, which was comparable to the standard antibiotics erythromycin and vancomycin, while maintaining over 90% cell viability in both HDFa and HaCaT cell lines. Untargeted metabolomic analysis suggested that antibacterial activity might be associated with compounds from the chemical families of alkaloids, terpenoids, and fatty acids, among others. These findings highlight the therapeutic potential of marine actinobacteria in underexplored environments as a promising strategy for treating acne vulgaris, a chronic inflammatory skin condition.

Chemical Elements of the Periodic Table in Indigenous Language as a Teaching Resource for Contextualized Chemistry/Science Teaching

Chemical Elements of the Periodic Table in Indigenous Language as a Teaching Resource for Contextualized Chemistry/Science Teaching

Ultrastable and ultra-accurate clock transitions in open-shell highly charged ions

Highly charged ions (HCIs) are less sensitive to external perturbations and are therefore attractive for the development of ultrastable clocks. However, only a few HCI candidates are known to provide optical clock transitions. In this work, we discover a large family of HCI clocks, with more than 100 suitable optical clock transitions hidden in the fine-structure terms of open-shell ions over 70 elements. Their projected instabilities and accuracies are στ~10−17/τ and δν/ν < 10−20, respectively, surpassing state-of-the-art optical clocks by several orders of magnitude. This indicates that having a high-performance optical clock transition is not a property of particular elements, but a virtue host by most elements from the periodic table. Furthermore, at given configurations, the clock transitions in heavy ions scale up to the XUV and soft-x-ray region, and thus enable the development of ultrastable clocks based on shorter wavelengths. The existence of multiple clock transitions in different charge states of a single element, as well as in a whole isoelectronic sequence would significantly enrich the search for new physics and the test of nuclear theories via high-precision spectroscopy.

THE ROLE OF jj COUPLING ON THE ENERGY LEVELS OF HEAVY ATOMS

The study of atomic spectroscopy has a profound relationship with quantum mechanics and its comprehension. Since Bohr’s success with a theory for the atom, it has been established that spectrum lines originate from transitions between different states. Moreover, the analysis of complex spectra reveals that there are groups of spectral lines that compose what is called a multiplet. To rationalize the multiplet structure, we need models to characterize and label the quantum states. The characterization of the atomic states is a common subject in classes of physical chemistry and inorganic chemistry, and there are basically two approaches to infer and label the energy states: (i) the LS coupling scheme and (ii) the jj coupling scheme. Usually, only the LS coupling is presented, and this ends up omitting its underlying assumptions. Here, we present a survey of both approaches, highlighting their premises and their adequacy towards different groups of the periodic table, ions, and excited states configurations. We show that by using benchmark data together with the Landé interval rule, the appropriate use of the jj coupling to understand the atomic spectra of heavier atoms is easily conveyed.

Mapping inorganic crystal chemical space.

The combination of elements from the Periodic Table defines a vast chemical space. Only a small fraction of these combinations yields materials that occur naturally or are accessible synthetically. Here, we enumerate binary, ternary, and quaternary element and species combinations to produce an extensive library of over 1010 stoichiometric inorganic compositions. The unique combinations are vectorised using compositional embedding vectors drawn from a variety of published machine-learning models. Dimensionality-reduction techniques are employed to present a two-dimensional representation of inorganic crystal chemical space, which is labelled according to whether the combinations pass standard chemical filters and if they appear in known materials databases.

Design, Synthesis and Application of 1,4-disubstituted 1,2,3-triazole Based Chemosensors: A Promising Avenue.

The 1,2,3-triazole-based chemosensors, synthesized through Cu(I)-catalyzed azide-alkyne cycloaddition via 'click chemistry', offer a straightforward yet highly effective method for detecting metal cations and anions with remarkable accuracy, selectivity and sensitivity, making them invaluable across various fields such as chemistry, pharmacology, environmental science and biology. The selective recognition of these ions is crucial due to their significant roles in biological and physiological processes, where even slight concentration variations can have major consequences. The article reviews literature from 2017 to 2024, highlighting advancements in the synthesis of 1,2,3-triazole-based ligands and their application (along with sensing mechanism) for detection of various ions causing health and environmental hazards. The detection aspects have been discussed sequentially for the transition-, inner transition-, and the metals from the s or p block of the periodic table.

Strengthening Motivation and Patterns of Student Constructs Towards the Use of JBUG Land in the Periodic Table of Elements Topic

Strengthening Motivation and Patterns of Student Constructs Towards the Use of JBUG Land in the Periodic Table of Elements Topic

Simultaneous targeted and non-targeted analysis of contaminants in fertilizers in Quebec, Canada.

In this study, an LC-MS based analytical method was developed and validated for the simultaneous targeted analysis (14 bisphenols and 14 plasticizers) and suspect screening of other plastic-related contaminants in various types of fertilizers. The ultrasound-assisted extraction method showed overall satisfactory performances, achieving a median absolute recovery of 85% for the target compounds in different types of fertilizers. The method was applied to sixteen different types of fertilizers, including fertilizing residual materials (n=8 types), one cattle manure, and seven mineral fertilizers collected in Quebec, Canada in 2022 and 2023. Relatively higher levels of the targeted bisphenols and plasticizers were detected in some fertilizing residual materials, such as municipal biosolids and deinking residues. 4-Hydroxyphenyl 4-isoprooxyphenylsulfone (D-8) and bis(2-ethylhexyl) phthalate (DEHP) were dominant contaminants in these matrixes, with concentrations up to 35.6 and 64.7μgg-1 dw, respectively. A non-targeted workflow was successfully applied to municipal biosolids and deinking residues, and >30 contaminants were identified across multiple chemical families at level 1 identification confidence, with most of them previously unreported in various types of fertilizers. For example, new color developers, N-(2-((Phenylcarbamoyl)amino)phenyl)benzenesulfonamide (NKK-1304) and 2,4-bis(phenylsulfonyl)phenol (DBSP), were reported in deinking residues. This work illustrates the complexity of the contaminant mixtures in fertilizers such as municipal biosolids and deinking residues.