bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemometrics as a tool for monitoring corrosion degradation of the selected alloys in real conditions
Authors: Vastag Gyöngyi , Apostolov Suzana , Ivošević Špiro , Rudolf Rebeka 
Published: April 2024

AbstractMonitoring of the corrosion process of alloys in real conditions often results in extensive data, which is characterized by complex interdependence, but by a large degree of mutual deviation. First of all, the large dispersion of the obtained results makes it very difficult to draw accurate conclusions about the real influence of the tested parameters on the corrosion behavior of alloys. On the other hand, in many cases, the high interdependence between the corrosion factors can also greatly burden the analyzed system and thus make it significantly difficult to recognize the main influence. Multivariate analysis, especially the principal component analysis, is becoming increasingly popular in processing of this type of data, due to its ability to recognize and eliminate redundant data. The aim of this study was to examine the possibility of using multivariate analysis methods in the processing of the corrosion test results obtained under real conditions. Based on the obtained results, it can be concluded that used multivariate method in combination with energy dispersive spectrometer analysis can be successfully used to identify the most important corrosion factors (type of corrosion environment, exposure time and technological production processes), as well as their influence on the degradation of the tested TiNi alloys under the given conditions.
Exploring the Magnetic Interactions in Two Novel Cyanide‐Bridged Homo‐ and Heterometallic Hexadecanuclear Complexes
Authors: Yadav Jyoti , Gupta Arindam , Mondal Arpan , Daumann Florian , Hörner Gerald , Weber Birgit , Konar Sanjit 
Published: April 2024

AbstractTwo novel isostructural cyanide‐bridged hexadecanuclear complexes with the general formula {[Fe(CN)6]6[M{en(Bn)py}]10}2+ [M=Fe (12+), Ni (22+)] have been synthesized. The structural analyses disclose the presence of multivalent Fe centres with different spin states in complex 12+ whereas all the Fe centres share a conserved oxidation state in complex 22+. The DC magnetic study revealed antiferromagnetic interactions between the adjacent metal centres and ferrimagnetic behaviour in 12+. On the other hand, ferromagnetic interactions were observed in complex 22+ due to nearly orthogonal orientation of the interacting orbitals and poor spatial overlap as observed in BS‐DFT calculations.
In Silico Design and Characterization of a New Molecular Electride: Li@Calix[3]Pyrrole
Authors: Saha Ranajit , Skjelstad Bastian Bjerkem , Pan Sudip 
Published: April 2024

AbstractElectrides, in which anionic electrons are localized independently of the atoms in the compound, have shown promise, especially as catalysts and optoelectronic materials. Here, we present a new computationally designed molecular electride, Li@calix[3]pyrrole (Li@C3P). Electron density and electron localization function analyses unequivocally confirm the existence of localized electride electron density, outside the system, independent of any specific atoms. Non‐covalent interaction plots further validate the character of the isolated localized electron, suggesting that the system can be accurately represented by Li+@calix[3]pyrrole ⋅ e−, denoting its distinct charge separation. The remarkable non‐linear optical properties of Li@C3P, including average polarizability,
=412.4 au, first hyperpolarizability, β=4.46×104 au, and second hyperpolarizability,
=18.40×106 au, are unparalleled in the previously reported and similar Li@C4P molecular electride. Furthermore, energy decomposition analysis in combination with natural orbital for chemical valence theory sheds light on the mechanism of electron density transfer from Li to the C3P cage, yielding the charge‐separated Li@C3P complex. In addition to the electron transfer, a key factor to its electride nature is the electronic structure of the CnP cage, which has its lowest unoccupied molecular orbital located in the void adjacent to the N−H groups at the back of the bowl‐shaped CnP cage.
Multiple Bonding in AeN− (Ae=Ca, Sr, Ba)
Authors: Cui Li‐Juan , Liu Yu‐Qian , Wang Meng‐Hui , Yan Bing , Pan Sudip , Cui Zhong‐Hua , Frenking Gernot 
Published: April 2024

AbstractQuantum chemical calculations using ab initio methods at the MRCI+Q(8,9)/def2‐QZVPPD and CCSD(T)/def2‐QZVPPD levels as well as using density functional theory are reported for the diatomic molecules AeN− (Ae=Ca, Sr, Ba). The anions CaN− and SrN− have electronic triplet (3Π) ground states with nearly identical bond dissociation energies De ~57 kcal/mol calculated at the MRCI+Q(8,9)/def2‐QZVPPD level. In contrast, the heavier homologue BaN− has a singlet (1Σ+) ground state, which is only 1.1 kcal/mol below the triplet (3Σ−) state. The computed bond dissociation energy of (1Σ+) BaN− is 68.4 kcal/mol. The calculations at the CCSD(T)‐full/def2‐QZVPPD and BP86‐D3(BJ)/def2‐QZVPPD levels are in reasonable agreement with the MRCI+Q(8,9)/def2‐QZVPPD data, except for the singlet (1Σ+) state, which has a large multireference character. The calculated atomic partial charges given by the CM5, Voronoi and Hirshfeld methods suggest small to medium‐sized Ae←N− charge donation for most electronic states. In contrast, the NBO method predicts for all species medium to large Ae→N− electronic charge donation, which is due to the neglect of the (n)p AOs of Ae atoms as genuine valence orbitals. Neither the bond orders nor the bond lengths correlate with the bond dissociation energies. The EDA−NOCV calculations show that the heavier alkaline earth atoms Ca, Sr, Ba use their (n)s and (n‐1)d orbitals for covalent bonding.
Engineering Modular DNA Reaction Networks for Signal Processing
Authors: Cui Shuang , Liu Xin , Zhang Xun , Shi Peijun , Zheng Yanfen , Wang Bin , Zhang Qiang 
Published: April 2024

AbstractDiversified molecular information‐processing methods have significant implications for nanoscale manipulation and control, monitoring and disease diagnosis of organisms, and direct intervention in biological activities. However, as an effective approach for implementing multifunctional molecular information processing, DNA reaction networks (DRNs) with numerous functionally specialized molecular structures have challenged them on scale design, leading to increased network complexity, further causing problems such as signal leakage, attenuation, and cross‐talk in network reactions. Our study developed a strategy for performing various signal‐processing tasks through engineering modular DRNs. This strategy is based on a universal core unit with signal selection capability, and a time‐adjustable signal self‐resetting module is achieved by combing the core unit and self‐resetting unit, which improves the time controllability of modular DRNs. In addition, multi‐input and ‐output signal cross‐catalytic and continuously adjustable signal delay modules were realized by combining core and threshold units, providing a flexible, precise method for modular DRNs to process the signal. The strategy simplifies the design of DRNs, helps generate design ideas for large‐scale integrated DRNs with multiple functions, and provides prospects in biocomputing, gene regulation, and biosensing.
Selective Lattice Doping Enables a Low‐Cost, High‐Capacity and Long‐Lasting Potassium Layered Oxide Cathode for Potassium and Sodium Storage
Authors: Ai Ruopeng , Zhang Xinyuan , Li Shuyue , Wei Zhixuan , Chen Gang , Du Fei 
Published: April 2024

AbstractLayered transition metal oxides are highly promising host materials for K ions, owing to their high theoretical capacities and appropriate operational potentials. To address the intrinsic issues of KxMnO2 cathodes and optimize their electrochemical properties, a novel P3‐type oxide doped with carefully chosen cost‐effective, electrochemically active and multi‐functional elements is proposed, namely K0.57Cu0.1Fe0.1Mn0.8O2. Compared to the pristine K0.56MnO2, its reversible specific is increased from 104 to 135 mAh g−1. In addition, the Cu and Fe co‐doping triples the capacity under high current densities, and contributes to long‐term stability over 500 cycles with a capacity retention of 68 %. Such endeavor holds the potential to make potassium‐ion batteries particularly competitive for application in sustainable, low‐cost, and large‐scale energy storage devices. In addition, the cathode is also extended for sodium storage. Facilitated by the interlayer K ions that protect the layered structure from collapsing and expand the diffusion pathway for sodium ions, the cathode shows a high reversible capacity of 144 mAh g−1, fast kinetics and a long lifespan over 1000 cycles. The findings offer a novel pathway for the development of high‐performance and cost‐effective sodium‐ion batteries.
14‐Membered Macrocyclic β‐Diiminato Gold(II) – A New Member for the Gold(II) Complex Family?
Authors: Sorge Lukas , Link Julian , Heinze Katja 
Published: April 2024

AbstractThe chemistry of molecular gold compounds is dominated by the oxidation states +I and +III. For the intermediate oxidation state +II with 5d9 electron configuration, dimerization or disproportionation of the gold(II) radicals is favored, so that only a few mononuclear gold(II) complexes have been isolated to date. The present study addresses the one‐electron reduction of the macrocyclic gold(III) complex [AuIIIL]+ of the innocent β‐diiminato ligand L2− with a 14‐membered macrocycle (L2−=5,7,12,14‐tetramethyl‐1,4,8,11‐tetraazacyclotetradeca‐5,7,12,14‐tetraenato). Electrochemistry, spectroelectrochemistry and chemical reduction of [AuIIIL]+ monitored by UV/Vis, NMR and EPR spectroscopy together with density functional theory calculations reveal disproportionation of the initially generated but elusive gold(II) complex AuIIL and provide guidelines for prospective stable mononuclear tetraazamacrocyclic gold(II) complexes.
Dynamics of Coordinated Phosphonate Group Directly Observed by 17O‐NMR in Lanthanide(iii) Complexes of a Mono(ethyl phosphonate) DOTA Analogue
Authors: Svítok Adam , Blahut Jan , Urbanovský Peter , Hermann Petr 
Published: April 2024

AbstractBiological phosphates can coordinate metal ions and their complexes are common in living systems. Dynamics of mutual oxygen atom exchange in the tetrahedral group in complexes has not been investigated. Here, we present a direct experimental proof of exchange (“phosphonate rotation”) in model Ln(III) complexes of monophosphonate H4dota analogue which alters phosphorus atom chirality of coordinated phosphonate monoester. Combination of macrocycle‐based isomerism with P‐based chirality leads to several diastereoisomers. (Non)‐coordinated oxygen atoms were distinguished through 17O‐labelled phosphonate group and their mutual exchange was followed by various NMR techniques and DFT calculations. The process is sterically demanding and occurs through bulky bidentate (κ2‐PO2)− coordination and was observed only in twisted‐square antiprism (TSA) diastereoisomer of large Ln(III) ions. Its energy demands increase for smaller Ln(III) ions (298ΔG≠(exp./DFT)=51.8/52.1 and 61.0/71.5 kJ mol−1 for La(III) and Eu(III), respectively). These results are helpful in design of such complexes as MRI CA and for protein paramagnetic NMR probes. It demonstrates usefulness of 17O NMR to study solution dynamics in complexes involving phosphorus acid derivatives and it may inspire use of this method to study dynamics of phosphoric acid derivatives (as e. g. phosphorus acid‐based inhibitors of metalloenzymes) in different areas of chemistry.
Reductions of Arenes using a Magnesium‐Dinitrogen Complex
Authors: Evans Matthew J. , Mullins Jeremy , Mondal Rahul , Jones Cameron 
Published: April 2024

AbstractIn this contribution, we present “Birch‐type”, and other reductions of simple arenes by the potassium salt of an anionic magnesium dinitrogen complex, [{K(TCHPNON)Mg}2(μ‐N2)] (TCHPNON=4,5‐bis(2,4,6‐tricyclohexylanilido)‐2,7‐diethyl‐9,9‐dimethyl‐xanthene), which acts as a masked dimagnesium(I) diradical in these reactions. This reagent is non‐hazardous, easy‐to‐handle, and in some cases provides access to 1,4‐cyclohexadiene reduction products under relatively mild reaction conditions. This system works effectively to reduce benzene, naphthalene and anthracene through magnesium‐bound “Birch‐type” reduction intermediates. Cyclohexadiene products can be subsequently released from the magnesium centres by protonolysis with methanol. In contrast, the reduction of substituted arenes is less selective and involves competing reaction pathways. For toluene and 1,3,5‐triphenylbenzene, the structural authentication of “Birch‐type” reduction intermediates is conclusive, although the formation of corresponding 1,4‐cyclohexadiene derivatives was low yielding. Reduction of anisole did not yield an isolable “Birch‐type” intermediate, but instead gave a C−O activation product. Treating triphenylphosphine with [{K(TCHPNON)Mg}2(μ‐N2)] resulted in the extrusion of both biphenyl and dinitrogen to afford a magnesium(II) phosphanide [{K(TCHPNON)Mg(μ‐PPh2)}2]. Reduction of fluorobenzene proceeded via C−F activation of the arene, and isolation of the magnesium(II) fluoride [{K(TCHPNON)Mg(μ‐F)}2]. Finally, the two‐electron reduction of 1,3,5,7‐cyclooctatetraene (COT) with [{K(TCHPNON)Mg}2(μ‐N2)] yielded a complex, [{K(TCHPNON)Mg}2(μ‐COT)], incorporating the aromatic dianion (COT2−).
Effect of Co‐Adsorbed Guest Adsorbates on the Separation of Ethylene/Ethane Mixtures on Metal‐Organic Frameworks with Open Metal Sites
Authors: Xiao Yuqing , Li Shenhui , Jiang Bin , Liang Xinmiao , Chu Yueying , Deng Feng 
Published: April 2024

AbstractDirect determination of the equilibrium adsorption and spectroscopic observation of adsorbent‐adsorbate interaction is crucial to evaluate the olefin/paraffin separation performance of porous adsorbents. However, the experimental characterization of competitive adsorption of various adsorbates at atomic‐molecular level in the purification of multicomponent gas mixtures is challenging and rarely conducted. Herein, solid‐state NMR spectroscopy is employed to examine the effect of co‐adsorbed guest adsorbates on the separation of ethylene/ethane mixtures on Mg‐MOF‐74, Zn‐MOF‐74 and UTSA‐74. 1H MAS NMR facilitates the determination of equilibrium uptake and adsorption selectivity of ethylene/ethane in ternary mixtures. The co‐adsorption of H2O and CO2 significantly leads to the degradation of ethylene uptake and ethylene/ethane selectivity. The detailed host‐guest and guest‐guest interactions are unraveled by 2D 1H−1H spin diffusion homo‐nuclear correlation and static 25Mg NMR experiments. The experimental results verify H2O coordinated on open metal sites can supply a new adsorption site for ethylene and ethane. The effects of guest adsorbates on the adsorption capacity and adsorption selectivity of ethylene/ethane mixtures are in the following order: H2O>CO2>O2. This work provides a direct approach for exploring the equilibrium adsorption and detailed separation mechanism of multicomponent gas mixtures using MOFs adsorbents.
Efficient Synthesis of Cyclohepta[b]indoles and Cyclohepta[b]indole‐Indoline Conjugates via RCM, Hydrogenation, and Acid‐Catalyzed Ring Expansion: A Biomimetic Approach
Authors: Parui Nabin , Mandal Tirtha , Maiti Sandip , Dash Jyotirmayee 
Published: April 2024

AbstractCyclohepta[b]indoles, prevalent in natural products and pharmaceuticals, are conventionally accessed via metal or Lewis acid‐mediated cycloadditions with prefunctionalized substrates. Our study introduces an innovative sequential catalytic assembly for synthesizing cyclohepta[b]indoles from readily available isatin derivatives. The process involves three catalytic sequences: ring‐closing metathesis, catalytic hydrogenation, and acid‐catalyzed ring expansion. The RCM of 2,2‐dialkene‐3‐oxindoles, formed by butenyl Grignard addition to 3‐allyl‐3‐hydroxy‐2‐oxindoles, yields versatile spirocyclohexene‐3‐oxindole derivatives. These derivatives undergo further transformations, including dibromination, dihydroxylation, epoxidation, Wacker oxidation at the double bond. Hydrogenation of spirocyclohexene‐3‐oxindole yields spirocyclohexane‐3‐oxindoles. Their subsequent acid‐catalyzed ring expansion/aromatization, dependent on the acid catalyst, results in either cyclohepta[b]indoles or cyclohepta[b]indole‐indoline conjugates, adding a unique synthetic dimension. The utility of this methodology is exemplified through the synthesis of an A‐FABP inhibitor, showcasing its potential in pharmaceutical applications.
Synthesis Strategies, Preparation Methods, and Applications of Chiral Metal‐Organic Frameworks
Authors: Zhang Hui , Cheng Qingsong , Pei Hebing , He Simin , Guo Ruibin , Liu Nijuan , Mo Zunli 
Published: April 2024

AbstractChiral Metal‐Organic Frameworks (CMOFs) is a kind of material with great application value in recent years. Formed by the coordination of metal ions or metal clusters with organic ligands. It has ordered and adjustable pores, multi‐dimensional network structure, large specific surface area and excellent adsorption properties. This material structure combines the properties of metal‐organic frameworks (MOFs) with the chiral properties of chiral molecules. It has great advantages in catalysis, adsorption, separation and other fields. Therefore, it has a wide range of applications in chemistry, biology, medicine and materials science. In this paper, various synthesis strategies and preparation methods of chiral metal‐organic frameworks are reviewed from different perspectives, and the advantages of each method are analyzed. In addition, the applications of chiral metal‐organic framework materials in enantiomer recognition and separation, circular polarization luminescence and asymmetric catalysis are systematically summarized, and the corresponding mechanisms are discussed. Finally, the challenges and prospects of the development of chiral metal‐organic frame materials are analyzed in detail.
Coconut fibre for the synthesis of microfibrillated cellulose: Thermal analysis experimental characterization
Authors: Moraes Fábio Pinto , Cordeiro Nathalia G. Barroso , Bojorge Ninoska , Alhadeff Eliana Mossé 
Published: April 2024

AbstractFibrillated cellulose at nano‐ and microscales was obtained from green coconut fibre. The biomass was subjected to mechanical treatment (comminution and sieving of the fibres) and chemical treatment (washed with water, treated with sodium hydroxide, bleached with sodium chlorite, and subjected to acid hydrolysis). Finally, purification steps included centrifugation, dialysis, and ultrasound. The product obtained by acid hydrolysis, the crude fibre, and the intermediate‐treated samples were examined by scanning electron microscopy (SEM) and characterized by chemical analysis and thermogravimetry (TGA/DTG). The chemical characterization for crude coconut fibre demonstrated 27.99% ± 1.98% for cellulose, 14.11% ± 4.44% for hemicellulose, 25.15% ± 0.04% for lignin, and 19.34% ± 0.02% for ashes. The applied pretreatment used to remove hemicellulose and lignin from the crude coconut fibre permitted obtaining high levels of cellulose, such as 94.94% ± 5.46% for the hardest condition, with NaOH 11% (w/v)/NaClO2. Then, acid hydrolysis was used to obtain the micro‐scale cellulose structures with 50% H2SO4 at 45°C for 90 min in an agitated condition (100 rpm). Following pretreatment with 2% and 11% NaOH/NaClO2, respectively, microfibrillated cellulose was verified at levels of 0.9% and 0.75% by thermogravimetric analysis, while the commercial sample had a verification level of 1.89%. The produced micro cellulose was fibrillated with a diameter equal to 149.39 ± 40.63 nm and a length of 1764.07 ± 1109.18 nm, as determined by SEM.
Parallel executive pallio‐motor loops in the pigeon brain
Authors: Steinemer Alina , Simon Annika , Güntürkün Onur , Rook Noemi 
Published: April 2024

AbstractA core component of the avian pallial cognitive network is the multimodal nidopallium caudolaterale (NCL) that is considered to be analogous to the mammalian prefrontal cortex (PFC). The NCL plays a key role in a multitude of executive tasks such as working memory, decision‐making during navigation, and extinction learning in complex learning environments. Like the PFC, the NCL is positioned at the transition from ascending sensory to descending motor systems. For the latter, it sends descending premotor projections to the intermediate arcopallium (AI) and the medial striatum (MSt). To gain detailed insight into the organization of these projections, we conducted several retrograde and anterograde tracing experiments. First, we tested whether NCL neurons projecting to AI (NCLarco neurons) and MSt (NCLMSt neurons) are constituted by a single neuronal population with bifurcating neurons, or whether they form two distinct populations. Here, we found two distinct projection patterns to both target areas that were associated with different morphologies. Second, we revealed a weak topographic projection toward the medial and lateral striatum and a strong topographic projection toward AI with clearly distinguishable sensory termination fields. Third, we investigated the relationship between the descending NCL pathways to the arcopallium with those from the hyperpallium apicale, which harbors a second major descending pathway of the avian pallium. We embed our findings within a system of parallel pallio‐motor loops that carry information from separate sensory modalities to different subpallial systems. Our results also provide insights into the evolution of the avian motor system from which, possibly, the song system has emerged.
Formation of Polyimide Membranes via Non‐Solvent Induced Phase Separation: Insight from Molecular Dynamics Simulations
Authors: Theodorakopoulos George V. , Karousos Dionysios S. , Favvas Evangelos P. , Gotzias Anastasios D. 
Published: April 2024

AbstractMolecular dynamics simulations were applied to investigate the formation of P84 polyimide membranes through the non‐solvent induced phase separation (NIPS) process, considering two scenarios: one using a conventional organic solvent like n‐methyl‐2‐pyrrolidone (NMP) and the other a greener alternative, γ‐butyrolactone (GBL), with water serving as the non‐solvent. Different compositions of polymer solutions were established along the binodal boundaries of the respective systems, derived from experimental cloud point data on the ternary phase diagram. The resulting polymer membranes were analyzed and compared in terms of their morphology. The wettability of their surfaces was notably affected by the polymer content in the initial casting solution and demonstrated a correlation with the Brunauer–Emmet–Teller (BET) specific surface area of the associated polymer nanostructures. The GBL solvent systems produced porous polymers qualitatively similar to those obtained with NMP, albeit with slightly narrower pore size distributions.