Lighter Homologues Research Articles

Determination of the Nature of Hydrocarbons in the Barents Sea (Verification of Remote Sensing Data)

Based on remote sensing data on the distribution of oil spills obtained using synthetic aperture radar (SAR) imagery of the Sentinel-1A and Sentinel-1B satellites in 2016–2022 and the results of the analysis of aliphatic hydrocarbons (AHCs) and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments taken in 2019–2022, the nature of oil slicks in various areas of the Barents Sea has been established. It is shown that the distribution of oil slicks in coastal areas is greatly influenced by anthropogenic hydrocarbon inflow (mainly from shipping and fishing), which is confirmed by elevated AHC concentrations in coastal sediments (up to 73 μg/g) and in the composition of Corg (up to 3.6%). In the central and northern regions of the Barents Sea (station 7105, in the coordinates 75.2–75.3 N, 31.5–31.8 E), the grouping of oil slicks is due to natural seepage of oil and gas. This is confirmed by the anomalous concentration of PAHs in the lower horizons of the obtained sediment column, and their composition (the dominance of 2-methylnaphthalene, a marker of their oil genesis). At the same time, the proportion of light homologues in the composition of alkanes increased, which may indicate their formation in the sedimentary sequence.

Theoretical predictions of properties and adsorption behaviour of a superheavy element Ts and its lighter homolog At, and of their various gas-phase compounds, on hydroxylated quartz surfaces from periodic DFT calculations

Adsorption energies, E ads, of a superheavy element Ts and its lighter homolog At, as well as of their various oxides, hydrides, and (oxy)hydroxides on hydroxylated quartz surfaces are calculated using a periodic density functional theory implemented in the AMS BAND software. It was shown that elemental At and Ts should be the most volatile over the quartz surfaces out of all the considered species, with E ads of the order of van der Waals bond energies, ∼25 kJ/mol. Hydride and hydroxide of At and Ts should be slightly less volatile than the elements with ∼20 kJ/mol larger E ads values. Oxides and oxyhydroxides of these elements should be the least volatile. All the compounds of Ts should be less volatile than the respective At ones. The differences in the E ads values between the Ts species should also be larger than those between the related At compounds, so that one should be able to differentiate between them more easily.

Reactivity of Ts and At oxides and oxyhydrides with a gold surface from periodic DFT calculations.

Adsorption energies, Eads, of oxides and oxyhydrides of the superheavy element (SHEs) Ts and of its lighter homologue At on the gold surface are predicted on the basis of relativistic periodic density functional theory calculations via AMS BAND software. The following compounds were considered: MO, MO2, MOO, and MO(OH) (where M = At and Ts). The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments on reactivity/volatility of SHEs. The results obtained indicate that all the molecules investigated should interact fairly strongly with the gold surface, with those of Ts being more reactive than At ones. The similarity in the Eads values of all the considered At compounds would make it challenging to differentiate between them while measuring their adsorption enthalpies, given experimental uncertainty. However, the difference in Eads among Ts compounds is more pronounced, so that one should be able to differentiate between the species.

A theoretical study of the adsorption behavior of superheavy 7p-elements and their compounds on a surface of gold in comparison with their lighter homologs.

Adsorption energies, Eads, of the 7th row superheavy elements (SHEs) Lv through Og, as well as of the homologous species of the 6th row elements Po through Rn on a gold surface are predicted on the basis of relativistic periodic density functional theory calculations via SCM BAND software. Since some of the elements can also form compounds such as hydrides and oxyhydrides under experimental conditions, the Eads values of the MH (M = Bi/Mc, Po/Lv, At/Ts and Rn/Og) and MOH (M = At/Ts and Rn/Og) molecules on a gold surface were also calculated. The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments on the reactivity/volatility of SHEs. The obtained results show that, in agreement with earlier predictions using somewhat different approaches and with experimental results on Hg, Cn and Rn, the adsorption strength of the elements on the Au(111) surface should follow the sequence: Hg > Fl > Og > Cn ≫ Rn, with the Eads values of less than 100 kJ mol-1. The other elements and their compounds under consideration should adsorb much more strongly on the gold surface with Eads values above 160 kJ mol-1, which should make them indistinguishable with respect to Eads in the chromatography column kept at room temperature and lower. However, with the further detector development, investigations of the chemical properties of these short-lived and less volatile SHEs and their compounds at high temperatures should be possible.

Effect of structural features of sedimentary cover on gas composition of permafrost table in northern West Siberia

Here, we analyzed geochemical indices of gases from core samples of permafrost table and evaluated data acquired from electric survey at the field of the Nadym-Pursk petroleum-bearing region. The Nadym-Pursk region is located in the northern West Siberia that is presently the major object of raw hydrocarbon (HC) exploration. The geologic exploration practice has demonstrated that the seismic survey efficiency is notably influenced by heterogeneous rocks of permafrost table, especially within permafrost distribution zones. The exploration efficiency for oil and gas can be enhanced using data from surface geochemical surveys that rely on vertical HC migration from deposits. The adequate interpretation of both seismic and geochemical survey data requires insights on the structure of permafrost table and on processes occurring therein. This study aimed to explore if geologic structural features of the territory affect the composition of gases dispersed in the permafrost table and identify the role of non-geological factors. The gas compositional features of the permafrost table were associated with HC migration channels, frost mounds, and probable gas hydrates within the permafrost distribution zone. The distribution of deep (He and H2) and catagenic (light methane homologues) gases stems from tectonic activity. This conclusion was made from the isotopic assay of samples from several holes, from the correlation between methane and homologues, from the presence of migration channels as per electric survey data, and essentially from the presence of deep gases. The enhanced content of methane is due to its active migration from both diagenetic zone (biogenic methane) and Cenomanian gas pay zones, which along with the respective geotemperature regime of subpermafrost strata is a favorable factor for gas hydrate generation. The natural connections between data from frost mounds point to their distinct genesis: the compositional genesis of gases is influenced by deep degassing and gas accumulation from diagenetic zones.

Relativistic coupled cluster calculations of the electron affinity and ionization potential of Nh(113)

Theoretical calculations based on the Dirac–Coulomb–Breit relativistic coupled cluster method have been carried out for the electron affinities and ionization potentials (IPs) of the superheavy element nihonium (Nh) and its lighter homologues In and Tl. The In and Tl calculations are in agreement with measurement within uncertainties. For Nh, where experiment is yet unknown, we predict the IP of 7.569(48) eV and electron affinity of 0.776(30) eV.

Five decades of GSI superheavy element discoveries and chemical investigation

Abstract Superheavy element research has been a strong pillar of the research program at GSI Darmstadt since its foundation. Six new elements were discovered along with many new isotopes. Initial results on chemical properties of the heaviest elements were obtained that allowed for comparing their behavior with that of their lighter homologs and with theoretical predictions. Main achievements of the past five decades of superheavy element research at GSI are described along with an outlook into the future of superheavy element research in Darmstadt.

Bare and ligand protected planar hexacoordinate silicon in SiSb3M3 + (M = Ca, Sr, Ba) clusters.

The occurrence of planar hexacoordination is very rare in main group elements. We report here a class of clusters containing a planar hexacoordinate silicon (phSi) atom with the formula SiSb3M3+ (M = Ca, Sr, Ba), which have D3h (1A1′) symmetry in their global minimum structure. The unique ability of heavier alkaline-earth atoms to use their vacant d atomic orbitals in bonding effectively stabilizes the peripheral ring and is responsible for covalent interaction with the Si center. Although the interaction between Si and Sb is significantly stronger than the Si–M one, sizable stabilization energies (−27.4 to −35.4 kcal mol−1) also originated from the combined electrostatic and covalent attraction between Si and M centers. The lighter homologues, SiE3M3+ (E = N, P, As; M = Ca, Sr, Ba) clusters, also possess similar D3h symmetric structures as the global minima. However, the repulsive electrostatic interaction between Si and M dominates over covalent attraction making the Si–M contacts repulsive in nature. Most interestingly, the planarity of the phSi core and the attractive nature of all the six contacts of phSi are maintained in N-heterocyclic carbene (NHC) and benzene (Bz) bound SiSb3M3(NHC)6+ and SiSb3M3(Bz)6+ (M = Ca, Sr, Ba) complexes. Therefore, bare and ligand-protected SiSb3M3+ clusters are suitable candidates for gas-phase detection and large-scale synthesis, respectively.

Interplay of Hydrogen and Halogen Bonding in the Crystal Structures of 2,6‐Dihalogenated Phenols

AbstractHydrogen and halogen bonds are important anisotropic attractive interactions in the molecular crystalline state. 2,6‐dibromophenol (1) was analyzed by single‐crystal X‐ray diffraction for the first time. The intermolecular interaction pattern was studied by Hirshfeld surface analysis along with 2D fingerprint diagrams. The characteristic interactions that dominate the crystal packing are electrostatic type‐II Br⋅⋅⋅Br interactions, O−H⋅⋅⋅O hydrogen bonds, and an offset parallel π‐stacking arrangement. Compound 1 was compared with 2,6‐difluoro‐ (2) and 2‐bromo‐6‐chlorophenol (3) in terms of their interplay between hydrogen and halogen bonding. Whereas the O−H⋅⋅⋅O hydrogen bond is more pronounced in the lighter homologues, the halogen⋅⋅⋅halogen interaction becomes a particularly important directional, attractive interaction in the crystal structure of 2,6‐dibromophenol.

Reactivity of the Superheavy Element 115, Mc, and Its Lighter Homologue, Bi, with Respect to Gold and Hydroxylated Quartz Surfaces from Periodic Relativistic DFT Calculations: A Comparison with Element 113, Nh.

Adsorption energies (Eads) of the superheavy element (SHE) Mc, its lighter homologue (Bi), as well as of another superheavy element Nh and some lighter homologues of SHEs on gold and hydroxylated quartz surfaces are predicted via periodic relativistic density functional theory calculations. The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments that are examining the reactivity and volatility of Mc. The obtained Eads values of the Bi and Mc atoms on the Au(111) surface are >200 kJ/mol. On the hydroxylated quartz surface, Mc should adsorb with a minimal energy of 58 kJ/mol. On both types of surfaces, Eads(Mc) should be ∼100 kJ/mol smaller than Eads(Bi) due to strong relativistic effects on its valence 7p electrons. A comparison with other SHEs under investigation shows that Mc should adsorb on gold more strongly than Cn, Nh, and Fl, while on quartz, Mc should adsorb like Nh, with both of them absorbing more strongly than volatile Cn and Fl. The highest reactivity of Mc in the row of the 7p elements is caused by the largest orbital and relativistic destabilization and expansion of the 7p3/2 atomic orbital. Using the calculated Eads, the distribution of the Nh and Mc events in the gas-phase chromatography column with quartz and gold-plated detectors is predicted via Monte Carlo simulations. As a result, Mc atoms should be almost 100% adsorbed in the first section of the chromatography column on quartz, while a few atoms of Nh can reach the second part of the column with gold-plated detectors.

Relativistic coupled-cluster calculation of the electric dipole polarizability and correlation energy of Cn, Nh+ , and Og: Correlation effects from lighter to superheavy elements

We employ a fully relativistic coupled-cluster theory to calculate the ground-state electric dipole polarizability and electron correlation energy of superheavy elements Cn, Nh$^+$ and Og. To assess the trend of electron correlation as function of $Z$, we also calculate the correlation energies for three lighter homologs--Zn, Cd and Hg; Ga$^+$, In$^+$ and Tl$^+$; Kr, Xe and Rn--for each superheavy elements. The relativistic effects and quantum electrodynamical corrections are included using the Dirac-Coulomb-Breit Hamiltonian with the corrections from the Uehling potential and the self-energy. The effects of triple excitations are considered perturbatively in the theory. Furthermore, large bases are used to test the convergence of results. Our recommended values of polarizability are in good agreement with previous theoretical results for all SHEs. From our calculations we find that the dominant contribution to polarizability is from the valence electrons in all superheavy elements. Except for Cn and Og, we observe a decreasing contribution from lighter to superheavy elements from the Breit interaction. For the corrections from the vacuum polarization and self-energy, we observe a trend of increasing contributions with $Z$. From energy calculations, we find that the second-order many-body perturbation theory overestimates the electron correlation energy for all the elements considered in this work.

Stibine as a reagent in molecular chemistry - targeted synthesis of primary and secondary stibanyl-gallanes and their lighter homologues.

The reactions of SbH3 with one or two equivalents of (Dipp2NacNac)Ga (Dipp2NacNac = HC{C(Me)N(Dipp)}2; Dipp = 2,6-iPr2C6H3) yield the primary and secondary stibanes (Dipp2NacNac)GaH(SbH2) (3) and {(Dipp2NacNac)GaH}2(SbH) (5). Their lighter homologs were obtained from the analogous reactions with phosphine and arsine. All compounds were characterized using heteronuclear NMR-spectroscopy, IR-spectroscopy and single-crystal X-ray diffraction.

Stepwise Bi-Bi Bond Formation: From a Bi-centered Radical to Bi4 Butterfly and Bi8 Cuneane-Type Clusters.

In contrast to their lighter homologues (P, As, Sb), the synthesis of polybismuthane clusters is still restricted to classical solid-state approaches. We herein report on systematic reduction reactions of different bismuth precursors with Ga(I) and Mg(I) complexes. This study not only yielded the first metal-coordinated tetrabismuthane ([{L1(Cl)Ga}2-μ,η1:1-Bi4] 3, L1 = HC[C(Me)N(2,6-i-Pr2C6H3)]2) and realgar-type bismuth cluster ([(L2Mg)4(μ4,η2:2:2:2-Bi8)] 4, L2 = HC[C(Me)N(2,4,6-Me3C6H2)]2) in addition to the bismuth-centered radical [L1Ga(Cl)]2Bi• 1 and dibismuthene [L1(Cl)GaBi]2 2, but clearly demonstrates the crucial role of the substituents and the oxidation state of the bismuth precursor as well as the specific reduction potential of the main group metal reductants on the product formation. Compounds 3 and 4 were spectroscopically characterized (1H, 13C NMR, IR), and the structures of 1-4 were determined by single-crystal X-ray diffraction. Computational calculations gave deeper insights into the electronic structures of 1', 3', and 4'.

High accuracy theoretical investigations of CaF, SrF, and BaF and implications for laser-cooling.

The NL-eEDM collaboration is building an experimental setup to search for the permanent electric dipole moment of the electron in a slow beam of cold barium fluoride molecules [NL-eEDM Collaboration, Eur. Phys. J. D 72, 197 (2018)]. Knowledge of the molecular properties of BaF is thus needed to plan the measurements and, in particular, to determine the optimal laser-cooling scheme. Accurate and reliable theoretical predictions of these properties require the incorporation of both high-order correlation and relativistic effects in the calculations. In this work, theoretical investigations of the ground and lowest excited states of BaF and its lighter homologs, CaF and SrF, are carried out in the framework of the relativistic Fock-space coupled cluster and multireference configuration interaction methods. Using the calculated molecular properties, we determine the Franck-Condon factors (FCFs) for the A2Π1/2→X2Σ1/2 + transition, which was successfully used for cooling CaF and SrF and is now considered for BaF. For all three species, the FCFs are found to be highly diagonal. Calculations are also performed for the B2Σ1/2 +→X2Σ1/2 + transition recently exploited for laser-cooling of CaF; it is shown that this transition is not suitable for laser-cooling of BaF, due to the nondiagonal nature of the FCFs in this system. Special attention is given to the properties of the A'2Δ state, which in the case of BaF causes a leak channel, in contrast to CaF and SrF species where this state is energetically above the excited states used in laser-cooling. We also present the dipole moments of the ground and excited states of the three molecules and the transition dipole moments (TDMs) between the different states. Finally, using the calculated FCFs and TDMs, we determine that the A2Π1/2→X2Σ1/2 + transition is suitable for transverse cooling in BaF.

From SRAFAP to ARCA and AIDA – developments and implementation of automated aqueous-phase rapid chemistry apparatuses for heavy actinides and transactinides

Abstract The development of automated rapid chemistry techniques and their application for batch-wise, chromatographic separations of heavy elements in the liquid-phase are outlined. Starting in the mid-1970s with manually performed separations using pressurized liquid-chromatography techniques, this development led to the first version of the Automated Rapid Chemistry Apparatus, ARCA, in the early 1980s. After a breakthrough to a much higher level of automation and miniaturization, the new apparatus ARCA II was built in the late 1980s. Based on it, the Automated Ion-exchange separation apparatus coupled with the Detection system for Alpha spectroscopy, AIDA, became operational in the late 1990s. In the context of technical and technological advancements, this article discusses the successful application of these instruments for (i) the search for superheavy elements, (ii) cross section measurements of actinide elements produced in multi-nucleon transfer reactions with actinide targets, (iii) chemical separation and characterization of the heavy actinides mendelevium, Md, and lawrencium, Lr, and (iv) studies of the transactinide elements rutherfordium, Rf, dubnium, Db, and seaborgium, Sg. Details of the separations are outlined together with the big advancements made over time and the limitations reached. For the transactinide elements, examples are given for their observed chemical behavior; often affected by an interplay between hydrolysis and complex formation. Influenced by relativistic effects, chemical properties of these elements sometimes deviated from those of their lighter homologs in the Periodic Table.

Development of nuclear chemistry at Mainz and Darmstadt

Abstract This review describes some key accomplishments of Günter Herrmann such as the establishment of the TRIGA Mark II research reactor at Mainz University, the identification of a large number of very neutron-rich fission products by fast, automated chemical separations, the study of their nuclear structure by spectroscopy with modern detection techniques, and the measurement of fission yields. After getting the nuclear chemistry group, the target laboratory, and the mass separator group established at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, a number of large international collaborations were organized exploring the mechanism of deeply inelastic multi-nucleon transfer reactions in collisions of Xe and U ions with U targets, Ca and U ions with Cm targets, and the search for superheavy elements with chemical separations after these bombardments. After the Chernobyl accident, together with members of the Institute of Physics, a powerful laser technique, the resonance ionization mass spectometry (RIMS) was established for the ultra-trace detection of actinides and long-lived fission products in environmental samples. RIMS was also applied to determine with high precision the first ionization potentials of actinides all the way up to einsteinium. In the late 1980ies, high interest arose in results obtained in fusion-evaporation reactions between light projectiles and heavy actinide targets investigating the chemical properties of transactinide elements (Z≥104). Remarkable was the observation, that their chemical properties deviated from those of their lighter homologs in the Periodic Table because their valence electrons are increasingly influenced by relativistic effects. These chemical results could be reproduced with relativistic quantum-chemical calculations. The present review is selecting and describing examples for fast chemical separations that were successful at the TRIGA Mainz and heavy-ion reaction studies at GSI Darmstadt.

Global and local approaches to population analysis: Bonding patterns in superheavy element compounds

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spinors with the same orbital angular momentum and different total angular momenta is demonstrated to be essential for understanding the peculiarities of chemical bonding in superheavy element compounds. The results are fully compatible with those obtained by the relativistic iterative version of conventional projection analysis of global density matrices.

Polychlorinated biphenyls (PCBs) in River Niger, Nigeria: Occurrence, distribution and composition profiles.

Contamination of rivers with persistent organic pollutants (POPs) is an issue of current global concern. Polychlorinated biphenyls (PCBs) are POPs with origin from commercial, incineration and industrial sources. Hence, there is a need for monitoring their occurrence and distribution in the environment. This study assessed the occurrence, distribution and composition profiles of PCBs in River Niger, Nigeria. Surface and bottom water samples were collected in consecutive quarters for a period of 2 years, covering the beginning and end of the rainy seasons and the dry seasons, from five locations (Gurara, Lokoja, Onitsha, Brass and Nicolas) along River Niger. A total of 240 water samples were collected using a Van Dorn water sampler. EPA method 3510c was used with slight modifications for sample preparation and analysis. The PCBs were analysed using a Hewlett Packard GC 5890 Series 11 with electron capture detection, and confirmation was made using a Shimadzu GCMS QP2010. The higher molecular weight marker PCBs (∑CB 138, 153 and 180) were more dominant than the lighter homologues (∑CB 28, 52 and 101), while commercial sources Co-PCBs (80.8 ± 61.7 to 288.3 ± 102.0 ng L-1) were more dominant than the incineration sources (34.9 ± 3.82 to 75.5 ± 65.2 ng L-1). The POPs load in River Niger water varied in both time and space. In surface water of the River Niger, ∑PCBs were higher during the rainy season, as a result of storm run-off from land-based sources. In the Brass and Nicolas Rivers during the dry season, the ∑PCBs were higher during low tide. There was no noticeable pattern during the rainy season. It may be concluded from this study that the water of River Niger is not good for human consumption or abstraction of water from the river for drinking water treatment.

Description of a Second Ferritin Light Chain Homologue From the Yellow Fever Mosquito (Diptera: Culicidae)

Ferritin is required for iron storage in vertebrates and for iron transport and storage in invertebrates, specifically insects. Classical ferritins consist of 24 subunits configured as a polyhedron wherein iron is held. The 24 subunits include light and heavy chains, each with specific functions. Several homologues of the light and heavy chains have been sequenced and studied in insects. In addition to iron transport and storage, ferritin has a role in dietary iron absorption, and functions as a protective agent preventing iron overload, decreasing oxidative stress, and reducing infection in these animals. The expression profile and regulation of a second ferritin light chain homologue (LCH2) in Aedes aegypti [Linnaeus (Diptera: Culicidae), yellow fever mosquito] was characterized in cells, animal developmental stages, and tissues post bloodmeal (PBM) by real-time PCR and immunoblot. Two previously studied ferritin subunits from Ae. aegypti, HCH and LCH1, along with LCH2 were immunoprecipitated and analyzed by mass spectrometry. The three Ae. aegypti ferritin subunits, HCH, LCH1, and LCH2, have different expression profiles and regulation with iron exposure, developmental stage, and tissue response PBM. Ae. aegypti expresses multiple and unique ferritin light chain subunits. Ae. aegypti, the vector for Zika, Dengue, and yellow fever, requires iron for oogenesis that is transported and stored in ferritin; this vector expresses a second light chain ferritin subunit homologue unlike any other species in which ferritin has been studied to date.

Hexacarbonyls of Mo, W, and Sg: Metal-CO Bonding Revisited.

Calculations of the first bond dissociation energies (FBDEs) and other molecular properties of M(CO)6, where M = Mo, W, and Sg, have been performed using a variety of nonrelativistic and relativistic methods, such as ZORA-DFT, X2c+AMFI-CCSD(T), and Dirac-Coulomb density functional theory. The aim of the study is to assist experiments on the measurements of the FBDE of Sg(CO)6. We have found that, different from the results published earlier, the metal-CO bond in Sg(CO)6 should be weaker than that in W(CO)6. A comparison of the relativistic and nonrelativistic FBDE values, as well as molecular orbital and vibrational frequency analyses within both the nonrelativistic and relativistic approaches, have shown that this is a relativistic, predominantly scalar, effect causing weaker d(M) → π(CO) back-bonding in Sg(CO)6 than in the lighter homologues. Good agreement between the calculated FBDEs in this work and the experimental FBDEs for the Mo and W compounds gives credit to the present FBDE of Sg(CO)6, which should serve as guidance for ongoing experiments.