Orbital Character Research Articles

Pyridine vs. Thiazole in Cyclometalated N^C^N Ni(II) Complexes

Six N^C^N cyclometalated Ni(II) complexes [Ni(N^C^N)Cl] or [Ni(N^C^N’)Br] with symmetric N^C^N or non-symmetric N^C^N’ ligands in which the peripheral N-groups were varied with pyridine (Py), 4-thiazole (4Tz), 2-thiazole (2Tz), and 2-benzothiazole (2Btz) complementing the previously reported complexes with di(2-pyridyl)phenide ligands [Ni(Py(Ph)Py)X] X = Cl or Br. The non-symmetric [Ni(N^C^N’)Br] complexes were synthesized from NiBr2 and N^CH^N’ protoligands through base-assisted nickelation, while the symmetric [Ni(N^C^N)Cl] complexes were received from the N^C(Cl)^N protoligands and [Ni(COD)2] (COD = 1,5-cyclooctadiene). Introduction of 4Tz on both sides shifted the electrochemical gap ΔEexp = Eox–Ered and the long wavelength UV-vis absorption maxima of the complexes to higher energies, while 2Tz leads to a shift to lower energies. When introducing only one 4Tz or 2Tz as peripheral groups, the remaining PhPy moiety dominates the electronic properties and electrochemistry and photophysics are very similar to the Py(Ph)Py derivatives. In contrast to this, introduction of 2Btz shifts both values to lower energies, regardless of one or two 2Btz groups and the 2Btz moiety dominates the character of the frontier molecular orbitals of the complexes, as DFT calculations show. Long-wavelength UV-vis absorptions vary from 416 to 443 nm, and their energies correlate well with the first reduction potentials. Negishi-type C–C cross-coupling reactions gave total yields ranging from 1 to 60% and cross-coupling yields from 1 to 44%. The reactivities correlate roughly with the first reduction potentials. Facilitated reduction (E around –2 or higher) goes generally along with improved performance, making the thiazole-containing complexes interesting candidates for such catalysis.

Flat Band Generation Through Interlayer Geometric Frustration in Intercalated Transition Metal Dichalcogenides.

Electronic flat bands can lead to rich many-body quantum phases by quenching the electron's kinetic energy and enhancing many-body correlation. The reduced bandwidth can be realized by either destructive quantum interference in frustrated lattices, or by generating heavy band folding with avoided band crossing in Moiré superlattices. Here a general approach is proposed to introduce flat bands into widely studied transition metal dichalcogenide (TMD) materials by dilute intercalation. A flat band with vanishing dispersion is observed by angle-resolved photoemission spectroscopy (ARPES) over the entire momentum space in intercalated Mn1/4TaS2. Polarization-dependent ARPES measurements combined with symmetry analysis reveal the orbital characters of the flat band. Supercell tight-binding simulations suggest that such flat bands arising from destructive interference between Mn and Ta on S through hopping pathways, are ubiquitous in a range of TMD families as well as for different intercalation configurations. The findings establish a new material platform to manipulate flat band structures and explore their corresponding emergent correlated properties.

Exceptionally Strong Triply Dative Be-F Bonds in [CO3]BeF- and [C2O4]BeF- Complexes: Reducing Valence Shell Electron Repulsion to Achieve High Bond Dissociation Energies.

Dative bonds are typically polar, weaker, and longer than electron-sharing covalent bonds. The intriguing diatomic BeF- anion uniquely exhibits triple Be-F dative bonding with a considerable bond dissociation energy (BDE) of 88 kcal/mol. Here, we report exceptionally strong dative-bonded systems, [CO3]BeF- and [C2O4]BeF-, with BDE values exceeding 155 kcal/mol by integrating [CO3] and [C2O4] groups into the BeF- framework. These designed C2v-symmetric molecules represent the lowest-energy configurations and maintain similar triply bonded Be-F interactions with orbital characteristics and bond distances closely resembling those in BeF-. Chemical bonding analysis reveals that [CO3] and [C2O4] groups significantly withdraw s-type nonbonding electrons from Be, which minimizes valence shell electron repulsion from the F- to Be interactions. This reduction in Pauli repulsion between the closed-shell fragments in [CO3]BeF- and [C2O4]BeF-, compared to that of BeF-, establishes a new record in dative bond strength and offers substantial insights into dative bonding mechanisms. The identified high thermodynamic and kinetic stability of these systems positions them as promising candidates for experimental detection in low-temperature matrices or the gas phase.

Ambipolar doping of a charge-transfer insulator in the Emery model

Understanding the similarities and differences between adding or removing electrons from a charge-transfer insulator may provide insights about the origin of the electron-hole asymmetry found in cuprates. Here we study with cellular dynamical mean-field theory the Emery model set in the charge-transfer insulator regime, and dope it with either electrons or holes. We consider the normal state only and focus on the doping evolution of the orbital character of the dopants and on the nature of the doping-driven transition. Regarding the orbital character of the dopants, we found an electron-hole asymmetry: doped electrons mostly enter the copper orbitals, whereas doped holes mostly enter the oxygen orbitals. Regarding the nature of the doping-driven transition, we found no qualitative electron-hole asymmetry: On either electron or hole doping, there is a two-stage transition from a charge-transfer insulator to a strongly correlated pseudogap and then to a metal. This shows that a strongly correlated pseudogap is an emergent feature of doped correlated insulators in two dimensions, in qualitative agreement with recent experiments on ambipolar Sr1−xLaxCuO2+y cuprate films. Our results indicate that merely doping with holes or electrons a charge-transfer insulator is not sufficient for explaining the electron-hole asymmetry observed in the normal state phase diagram of cuprates. Our work reinforces the view that actual hole-doped cuprates are more correlated than their electron-doped counterparts. Published by the American Physical Society 2025

Solar Energy Datasets of Deep Learning Models Incorporating with GK-2A and ASOS Ground Measurements

This study presents the construction and evaluation of a dataset for estimating solar energy using the GK<sup>-2</sup>A satellite and deep learning. The GK<sup>-2</sup>A is currently utilized in real-time for weather observations over the Korean Peninsula. The GK<sup>-2</sup>A satellite features 16 channels, producing radiative channel images at spatial resolutions ranging from 500 m to 2 km, with temporal intervals as short as 2 minutes depending on the area. These satellite data are used in various fields, including meteorology, oceanography, vegetation monitoring, and renewable energy. In this study, we used spectral channel data from the GK<sup>-2</sup>A expended local area satellite from January 2021 to December 2022. For training and evaluating the accuracy of the deep learning model, we utilized data from 98 automated synoptic observing system ground observation sites operated by the Korea Meteorological Administration. A back-propagation neural network model, which showed meaningful results in estimating solar energy, was applied. Various hyperparameters were optimized, and data preprocessing and separation were conducted to optimize the model. The study also compared the performance of the deep learning model with physical models. The BPNN deep learning model achieved a statistical accuracy of root mean squared error (RMSE) 77.32 Wm<sup>-2</sup>, mean bias error (MBE) -0.48 Wm<sup>-2</sup>, and R<sup>2</sup> 0.91, indicating high accuracy. In contrast, the physical model showed an RMSE of 132.01 Wm<sup>-2</sup>, MBE -76.51 Wm<sup>-2</sup>, and an R<sup>2</sup> of 0.74, displaying relatively lower accuracy compared to the deep learning model. Additionally, the spatio-temporal map of solar energy generated by the deep learning model successfully captured the attenuation of radiation due to clouds and the variation in solar energy based on the position of the sun. The solar energy data produced in this study are expected to be useful as input data for various fields such as meteorology, agriculture, environmental monitoring, and marine sciences.

Improved Surface Solar Irradiation Estimation Using Satellite Data and Feature Engineering

Planning an optimal installation site to maximize power-generation efficiency is crucial for the effective operation of photovoltaic power plants. Achieving this requires accurate, reliable information on solar irradiation across different regions. However, ground-based measurements using pyranometers are resource-intensive, requiring substantial time and human effort, and their measurement range is limited, complicating data collection. To address this, we propose a method to accurately estimate surface solar irradiation (SSI) using satellite data and feature engineering. By leveraging satellite data as the primary input, we overcome the spatial and temporal limitations of ground-based measurements. Additionally, we improve SSI-estimation performance through designed features based on the geometric information of the Sun and satellite. A hybrid deep neural network model is used for SSI estimation, effectively handling data of varying dimensions. Hourly SSI data from 12 synoptic observation stations collected over one year, excluded from the model’s training and validation sets, are utilized to evaluate the proposed method. Experimental results demonstrate strong SSI-estimation performance, with an average root mean square error (RMSE) of 0.1813 MJ/m2, a relative RMSE of 0.1601, mean absolute error of 0.1159 MJ/m2, and coefficient of determination of 0.9680.

Orbital Eccentricity Study of Planets: A Comparative Analysis of Manual Simulation and Digital Visualization

Understanding planetary orbits is a fundamental concept in astronomy. Many secondary school students encounter difficulties comprehending the shape and characteristics of orbits, which are not perfect circles but ellipses with varying degrees of eccentricity. These challenges are particularly evident when students are tasked with sketching or calculating the eccentricity of a planet's orbit, a measure of how elongated the orbit is. This study aims to explore and compare the efficacy of two pedagogical approaches manual simulation and digital simulation—in enhancing students' understanding of planetary orbit shapes and the concept of eccentricity. A descriptive-comparative research design is employed to depict and contrast the effectiveness of these two teaching methods. The experiment, crafted based on expert design, involves four qualified astronomy educators to apply both approaches. The manual simulation requires students to draw orbits and compute eccentricity manually, whereas the digital simulation leverages software to visualize the motion of planetary orbits. Evaluation is conducted through Focus Group Discussions (FGD) with four subject matter experts to provide feedback on the effectiveness of the two methods, the challenges faced by students, and the level of comprehension achieved. The results from the manual experiment indicate that the orbital eccentricity ranges between 0.2 and 0.4, suggesting that the planets' orbits are elliptical. These findings align with Kepler’s laws, which state that planetary orbits are elliptical, with the Sun at one of the foci. Results from the NASA Eyes application further corroborate this, showing that the orbits of planets in the solar system are indeed elliptical, both at perihelion (the point closest to the Sun) and aphelion (the end farthest from the Sun). In conclusion, this research substantiates that the orbits of planets in the solar system are elliptical, consistent with Kepler's laws.

A High-Resolution Spotlight Imaging Algorithm via Modified Second-Order Space-Variant Wavefront Curvature Correction for MEO/HM-BiSAR

A bistatic synthetic aperture radar (BiSAR) system with a Medium-Earth-Orbit (MEO) SAR transmitter and high-maneuvering receiver (MEO/HM-BiSAR) can achieve a wide swath and high resolution. However, due to the complex orbit characteristics and the nonlinear trajectory of the receiver, MEO/HM-BiSAR high-resolution imaging faces two major challenges. First, the complex geometric configuration of the BiSAR platforms is difficult to model accurately, and the ‘non-stop-go’ effects should also be considered. Second, non-negligible wavefront curvature caused by the nonlinear trajectories introduces residual phase errors. The existing spaceborne BiSAR imaging algorithms often suffer from image defocusing if applied to MEO/HM-BiSAR. To address these problems, a novel high-resolution imaging algorithm named MSSWCC (Modified Second-Order Space-Variant Wavefront Curvature Correction) is proposed. First, a high-precision range model is established based on an analysis of MEO SAR’s orbital characteristics and the receiver’s curved trajectory. Based on the echo model, the wavefront curvature error is then addressed by two-dimensional Taylor expansion to obtain the analytical expressions for the high-order phase errors. By analyzing the phase errors in the wavenumber domain, the compensation functions can be designed. The MSSWCC algorithm not only corrects the geometric distortion through reverse projection, but it also compensates for the second-order residual spatial-variant phase errors by the analytical expressions for the two-dimensional phase errors. It can achieve high-resolution imaging ability in large imaging scenes with low computational load. Simulations and real experiments validate the high-resolution imaging capabilities of the proposed MSSWCC algorithm in MEO/HM-BiSAR.

Evaluating the Anticancer Properties of Novel Piscidinol A Derivatives: Insights from DFT, Molecular Docking, and Molecular Dynamics Studies.

Cancer is characterized by uncontrolled cell growth and spreading throughout the body. This study employed computational approaches to investigate 18 naturally derived anticancer piscidinol A derivatives (1-18) as potential therapeutics. By examining their interactions with 15 essential target proteins (HIF-1α, RanGAP, FOXM1, PARP2, HER2, ERα, NGF, FAS, GRP78, PRDX2, SCF complex, EGFR, Bcl-xL, ERG, and HSP70) and comparing them with established drugs such as camptothecin, docetaxel, etoposide, irinotecan, paclitaxel, and teniposide, compound 10 emerged as noteworthy. In molecular dynamics simulations, the protein with the strongest binding to the crucial 1A52 protein exceeded druglikeness criteria and displayed extraordinary stability within the enzyme's pocket over varied temperatures (300-320 K). Additionally, density functional theory was used to calculate dipole moments and molecular orbital characteristics, as well as analyze the thermodynamic stability of the putative anticancer derivatives. This finding reveals a well-defined, potentially therapeutic relationship supported by theoretical analysis, which is in good agreement with subsequent assessments of their potential in vitro cytotoxic effects of piscidinol A derivatives (6-18) against various cancer cell lines. Future in vivo and clinical studies are required to validate these findings further. Compound 10 thus emerges as an intriguing contender in the fight against cancer.

Application of Voronoi Polyhedra for Analysis of Electronic Dimensionality in Emissive Halide Materials.

The synthesis of new hybrid halide materials is attracting increasing research interest due to their potential optoelectronic applications. However, general design principles that explain and predict their properties are still limited. In this work, we attempted to reveal the role of intermolecular interactions on the optical properties in a series of hybrid halides with an (EtnNH4-n)2Sn1-xTexCl6 (n = 1-4) composition. DFT calculations showed that the dispersions of the bands involving the Te 5s orbital character gradually decrease as the size of the organic cation increases, indicating a reducing orbital overlap between neighboring TeCl62- complexes. We characterized the photoluminescence (PL) of the Sn/Te solid solutions in (EtnNH4-n)2Sn1-xTexCl6 (n = 1-4) phases to correlate the electronic and optical properties. The PL response shows no concentration quenching effects in the (Et4N)2Sn1-xTexCl6 series, which demonstrated electronically isolated TeCl62- complexes. However, the series with smaller organic cations (n = 1-3) and higher electronic dimensionality show concentration quenching effects, which decrease as a function of the Te 5s band dispersions in these compounds. Similar trends can be revealed using a simple semiquantitative electronic dimensionality analysis method by means of Voronoi polyhedra. Since this approach relies only on structural data, it enables rapid characterization of orbital overlap between metal halide complexes in hybrid materials without DFT calculations. The present results allow us to conclude that electronic dimensionality plays an essential role in the photophysical properties of hybrid halide compounds and can be used to fine-tune their properties.

Geodesics of Finsler Hayward black hole surrounded by quintessence

This research paper delves into examining the Hayward black hole structure surrounded by quintessence within the framework of Finsler geometry. Our focus centers on the Finsler metric tensor development for black holes. This newly derived metric introduces significant deviations from regular black hole metrics found in general relativity due to the Finslerian term γ presence, thus shedding fresh insights into the geometry and nature of black holes. Our findings reveal that the metric structure aligns closely with known Riemannian limits, affirming the congeniality of our model with existing theories. Furthermore, we extended our analysis to derive critical mass values and determine the normalization factor for the Hayward black hole within the Finlserian framework. The study encompasses a detailed description of the horizons and extremal conditions of the Hayward black hole surrounded by quintessence and the impact of the Finsler parameter γ on them. Specifically, we explore the case where the quintessence state parameter is set to ω=-2/3. Our analysis delves into the effective potential, providing insights into null geodesics for various energy levels and examining the behavior of horizons by utilizing the definition of the effective potential. We also discuss the impact of γ for the same. We compute and analyze the radius of circular orbits, the period, the instability characteristics of circular orbits, and the force acting on photons with the newly introduced parameter γ within the quintessence field. We have thoroughly looked over the obtained results and discussed them. Additionally, we explore the shadow of the black hole in this context. Thereby, the validity and consistency of our Finslerian model are strengthened. In addition to increasing our understanding of black hole physics, this study paves the way for further research in the Finsler geometry domain and its applications in astrophysics.

Identifying N Coordination Types of Single‐Atom Catalysts by Spin‐Modulated Luminol Cathodic Electrochemiluminescence

The type of coordinated N atoms in the metal‐N coordination structure is of paramount importance to the catalytic property of carbon‐based metal single‐atom catalysts (SACs). Extended X‐ray absorption fine structure (EXAFS) spectroscopy is a powerful tool for analyzing the coordination environments of SACs. Despite its efficacy, the limited availability of synchrotron light sources and the complexity of data analysis have constrained its broader application in identifying metal‐N coordination types within SACs. In this work, two kind of CoN4 SACs were prepared by varying the N source. Then their electrochemiluminescence (ECL) behavior in the luminol/dissolved oxygen system during cathodic scanning were investigated. In comparison to CoN4(pyridinic N), for which the spin density displays dz2 orbital characteristics, CoN4(pyrrolic N) exhibits dxz orbital features, which was more conducive to the subsequent cleavage of the O‐O bond in O2•‐ to •OH, resulting in the generation of more active intermediates *OH and the promotion of cathodic ECL emission. This work demonstrates that the ECL technique provides a novel method for the rapid identification of Co‐N coordination types and the spin nature of the metal center in CoN4 SACs.

Identifying N Coordination Types of Single-Atom Catalysts by Spin-Modulated Luminol Cathodic Electrochemiluminescence.

The type of coordinated N atoms in the metal-N coordination structure is of paramount importance to the catalytic property of N-modified carbon-based single-atom catalysts (SACs). Extended X-ray absorption fine structure (EXAFS) spectroscopy is a powerful tool for analyzing the coordination environments of SACs. Despite its efficacy, the limited availability of synchrotron light sources and the complexity of data analysis have constrained its broader application in identifying metal-N coordination types within SACs. In this work, two kind of CoN4 SACs, were prepared by varying the N source. Then their electrochemiluminescence (ECL) behavior in the luminol/dissolved oxygen system during cathodic scanning were investigated. In comparison to CoN4(pyridinic N), for which the spin density displays dz2 orbital characteristics, CoN4(pyrrolic N) exhibits dxz orbital features, which was more conducive to the subsequent cleavage of the O-O bond in O2⋅- to ⋅OH, resulting in the generation of more active intermediates *OH and the promotion of cathodic ECL emission. This work demonstrates that the ECL technique provides a novel method for the rapid identification of Co-N coordination types and the spin nature of the metal center in CoN4 SACs.

Stable π Radical BDPA: Adsorption on Cu(100) and Survival of Spin.

The adsorption of the radical α,ɣ-bisdiphenylene-β-phenylallyl (BDPA) molecule to the Cu(100) surface was studied using scanning tunnelling microscopy (STM), scanning tunnelling spectroscopy (STS), and density functional theory (DFT) calculations accounting for dispersion forces. BDPA on Cu(100) was observed to align preferentially along directions due to weak Cu-C chemisorption between fluorenyl carbons with the underlying copper atoms. The curved shape of the BDPA molecule on Cu(100) can be ascribed to the lack of molecular orbital character on the phenyl substituent. A Kondo-like feature from differential conductance (dI/dV) measurements centered close to the Fermi energy ( ) suggests the retention of an electron spin-1/2 state, which is corroborated by hybrid DFT calculations that place the SOMO (singly occupied molecular orbital) below and SUMO (singly unoccupied molecular orbital) above for BDPA adsorbed to Cu(100).

Orbital Analysis of a Dual Asteroid System Explorer Based on the Finite Element Method

In the study of dual asteroid systems, a model that can rapidly compute the motion and orientation of these bodies is essential. Traditional modeling techniques, such as the double ellipsoid or polyhedron methods, fail to deliver sufficient accuracy in estimating the interactions between dual asteroids. This inadequacy primarily stems from the non-tidally locked nature of asteroid systems, which necessitates continual adjustments to account for changes in gravitational fields. This study adopts the finite element method to precisely model the dynamic interaction forces within irregular, time-varying dual asteroid systems and, thereby, enhance the planning of spacecraft trajectories. It is possible to derive the detailed characteristics of a spacecraft’s orbital patterns via the real-time monitoring of spacecraft orbits and the relative positions of dual asteroids. Furthermore, this study examines the orbital stability of a spacecraft under various trajectories, revealing that orbital stability is intrinsically linked to the geometric configuration of the orbits. And considering the influence of solar pressure on the orbit of asteroid detectors, a method was proposed to characterize the stability of detector orbits in the time-varying gravitational field of binary asteroids using cloud models. The insights gained from the analysis of orbital characteristics can inform the design of landing trajectories for binary asteroid systems and provide data for deep learning algorithms that are aimed at optimizing such orbits. By introducing the application of the finite element method, detailed analysis of spacecraft orbit characteristics, and a stability characterization method based on a cloud model, this paper systematically explores the logic and structure of spacecraft orbit planning in a dual asteroid system.

Investigating the Mean Temperature of Accretion Disks and Mass Transfer Rates in Cataclysmic Variable Stars through Orbital Characteristics

Cataclysmic variable (CV) stars, characterized by their dynamic binary systems composed of a white dwarf and a donor red dwarf star, exhibit intricate mass transfer processes crucial for understanding their evolutionary pathways. This study delved into the theoretical investigation of mass transfer processes occurring within non-magnetic CV stars analyzing their orbital characteristics. A selection of eleven CV systems, encompassing a diverse range of subcategories, were chosen for the analysis of this research. Well-established Fourier and Lomb-Scargle algorithms were utilized to identify the most effective algorithm in determining the periodicity of their light curves. The calculated orbital periods for the aforementioned CV sample were then leveraged to determine the mean temperature of their accretion disks. This determination was achieved through established techniques which used spectroscopic Balmer emission lines and Stromgren photometric observations. These techniques provide robust measurements of the physical properties of accretion disks within CVs. Finally, a strong correlation was established between mean temperature of the disk which determined through spectroscopic method and system’s mass transfer rate which determined via various techniques and algorithms.

Unraveling the Band Structure and Orbital Character of a π-Conjugated 2D Graphdiyne-Based Organometallic Network.

Graphdiyne-based carbon systems generate intriguing layered sp-sp2 organometallic lattices, characterized by flexible acetylenic groups connecting planar carbon units through metal centers. At their thinnest limit, they can result in 2D organometallic networks exhibiting unique quantum properties and even confining the surface states of the substrate, which is of great importance for fundamental studies. In this work, the on-surface synthesis of a highly crystalline 2D organometallic network grown on Ag(111) is presented. The electronic structure of this mixed honeycomb-kagome arrangement - investigated by angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy - reveals a strong electronic conjugation within the network, leading to the formation of two intense electronic band-manifolds. In comparison to theoretical density functional theory calculations, it is observed that these bands exhibit a well-defined orbital character that can be associated with distinct regions of the sp-sp2 monomers. Moreover, it is found that the halogen by-products resulting from the network formation locally affect the pore-confined states, causing a significant energy shift. This work contributes to the understanding of the growth and electronic structure of graphdiyne-like 2D networks, providing insights into the development of novel carbon materials beyond graphene with tailoredproperties.

Theoretical Determination of Intensity of Satellite Structure of the Tungsten (W) Lα1, 2 X-Ray Spectrum

The tungsten Lα1,2 x-ray spectrum contains anomalous satellite feature Lα', thus receiving special attention. The theoretical attempt at determining the intensity of this feature is highly discrepant from the experimental result. This discrepancy has been the subject of much discussion. In the present work it has been shown theoretically that by extending the Bohm-Pines Hamiltonian and using many-body theory, satellite intensity thus obtained is in good agreement with the experiment; hence resolving the discrepancy.

Aromaticity in Isoelectronic Analogues of Benzene, Carborazine and Borazine, from Electronic Structure and Magnetic Property.

Carborazine (B2C2N2H6) and borazine (B3N3H6) are isoelectronic analogues of benzene (C6H6). The aromatic character of borazine have basically reached a consensus after a long period of controversy, but the related properties of carborazine are even rarely reported. In this work, we systematically investigated the geometric structure, charge distribution, frontier molecular orbital characteristics, bonding, electronic delocalization, magnetic shielding effect, and induced ring current of carborazine and borazine, and compared the studied characteristics with those of benzene to determine the aromatic character of the two analogues. The combination of multiple properties shows that although they are isoelectronic, carborazine is evidently aromatic, while borazine only exhibits rather weak aromaticity. The C atom acting as a connecting bridge between B and N atoms in carborazine reduces the electronegativity difference on the molecular backbone and enhances the electronic delocalization over the conjugated path, which is the essence of the distinct disparity of aromaticity between carborazine and borazine.

The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b

Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but it has been unclear if they also result from different planet formation processes, and if there is a trend linking the planetary density to the chemical composition of the host star. In this work, we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b (P ≃ 2.5 d, Rp ≃ 1.22 RJ, Mp = 0.72 MJ) and TOI-2981 b (P ≃ 3.6 d, RP ≃ 1.2 RJ, MP = 2 MJ) are hot Jupiters on nearly circular orbits, while TOI-4914 b (P ≃ 10.6 d, RP ≃ 1.15 RJ, Mp = 0.72 MJ) is a warm Jupiter with a significant eccentricity (e = 0.41 ± 0.02) that orbits a star more metal-poor ([Fe/H] = −0.13) than most of the stars known to host giant planets. Similarly, TOI-2981 b orbits a metal-poor star ([Fe/H] = −0.11), while TOI-2714 b orbits a metal-rich star ([Fe/H] = 0.30). Our radial velocity follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23σ, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18σ). TOI-4914 b, with its large radius (Rp ≃ 1.15 RJ) and low insolation flux (F⋆ < 2 × 108 erg s−1 cm−2), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems.