The Enhanced Actinide Removal Plant (EARP), at Sellafield in the UK, is tasked with separating waste actinide species from an aqueous waste stream via base-induced hydrolysis of Fe(III). During this flocculation process ferrihydrite forms and the actinides interact strongly with the surface. It has been shown that Pu remains sorbed in the solid state over long periods of time, during which ferrihydrite undergoes transformation into hematite. It is of critical importance to the operations of future Geological Disposal Facility (GDF) technologies that the Pu@hematite system is studied to understand the binding strength and sorption mechanism.Here we present a comprehensive study of Pu(IV) binding to two well-established basal terminations of hematite using periodic DFT + U eff . First, we outline our methodology and demonstrate correct prediction of the bulk hematite lattice parameters and electronic band gap, then we generate the (001)-Fe and (001)-O 3 terminations and demonstrate reasonable predictions of the surface energies, inter-layer spacings, and work functions. The (001)-Fe termination is then hydrated with a monolayer of water. We show that Pu(IV) forms multiple Pu-O bonds with both terminations at distances consistent with experimental EXAFS measurements. Density of states and charge density difference analysis reveals strong hybridisation between the Pu(5f) and O(2p) states supporting charge transfer as indicated by depleted charge density surrounding the Pu atom on the surface. Quantum Theory of Atoms in Molecules analysis shows that the Pu-O bonds are partially covalent, in agreement with our previous assessment of Pu bound to α-Fe13, a prenucleation cluster to ferrihydrite (Fh), and Pu bound to ferrihydrite surfaces. The reaction energies for surface binding are significantly exothermic, even more so than was found in our previous analysis of the Pu@Fh surfaces, indicating that Pu(IV) should remain immobile and bound to hematite, particularly in oxygenated conditions as may be found in the GDF or subterranean environments.
位于英国塞拉菲尔德的增强型锕系元素去除厂（EARP）的任务是通过碱基诱导的铁（III）水解从水废液中分离出锕系元素。在絮凝过程中，水合铁形成，锕系元素与表面强烈相互作用。研究表明，在较长一段时间内，稀土在固体状态下仍保持吸附状态，在此过程中，铁水合体转变为赤铁矿。研究Pu@hematite体系的结合强度和吸附机理对未来地质处置设施（GDF）技术的运行具有重要意义。在这里，我们使用周期性DFT + U eff对Pu（IV）与两个已建立的赤铁矿基端结合进行了全面的研究。首先，我们概述了我们的方法，并证明了对赤铁矿体晶格参数和电子带隙的正确预测，然后我们生成了(001)-Fe和(001)-O 3终端，并证明了对表面能、层间间距和功函数的合理预测。然后将(001)-Fe末端与一层水水合。我们发现，Pu（IV）形成多个Pu- o键，其两端的距离与实验EXAFS测量值一致。态密度和电荷密度差分析表明，表面Pu原子周围的耗尽电荷密度表明，Pu（5f）和O（2p）态之间存在强烈的杂化作用，支持电荷转移。分子原子量子理论分析表明，Pu- o键是部分共价的，这与我们之前对Pu与α-Fe13结合，与铁水合体（Fh）形成预成核簇以及Pu与铁水合体表面结合的评估一致。表面结合的反应能明显是放热的，甚至比我们之前对Pu@Fh表面的分析发现的还要多，这表明Pu（IV）应该保持不动并与赤铁矿结合，特别是在GDF或地下环境中可能发现的氧化条件下。
{"title":"The Interaction of Pu(IV) with the Hematite (001) Terminations: A Periodic Boundary Condition DFT Study","authors":"Ryan L. Dempsey, Nikolas Kaltsoyannis","doi":"10.1039/d6dt00183a","DOIUrl":"https://doi.org/10.1039/d6dt00183a","url":null,"abstract":"The Enhanced Actinide Removal Plant (EARP), at Sellafield in the UK, is tasked with separating waste actinide species from an aqueous waste stream via base-induced hydrolysis of Fe(III). During this flocculation process ferrihydrite forms and the actinides interact strongly with the surface. It has been shown that Pu remains sorbed in the solid state over long periods of time, during which ferrihydrite undergoes transformation into hematite. It is of critical importance to the operations of future Geological Disposal Facility (GDF) technologies that the Pu@hematite system is studied to understand the binding strength and sorption mechanism.Here we present a comprehensive study of Pu(IV) binding to two well-established basal terminations of hematite using periodic DFT + U eff . First, we outline our methodology and demonstrate correct prediction of the bulk hematite lattice parameters and electronic band gap, then we generate the (001)-Fe and (001)-O 3 terminations and demonstrate reasonable predictions of the surface energies, inter-layer spacings, and work functions. The (001)-Fe termination is then hydrated with a monolayer of water. We show that Pu(IV) forms multiple Pu-O bonds with both terminations at distances consistent with experimental EXAFS measurements. Density of states and charge density difference analysis reveals strong hybridisation between the Pu(5f) and O(2p) states supporting charge transfer as indicated by depleted charge density surrounding the Pu atom on the surface. Quantum Theory of Atoms in Molecules analysis shows that the Pu-O bonds are partially covalent, in agreement with our previous assessment of Pu bound to α-Fe13, a prenucleation cluster to ferrihydrite (Fh), and Pu bound to ferrihydrite surfaces. The reaction energies for surface binding are significantly exothermic, even more so than was found in our previous analysis of the Pu@Fh surfaces, indicating that Pu(IV) should remain immobile and bound to hematite, particularly in oxygenated conditions as may be found in the GDF or subterranean environments.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"536 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kaname Shibata, Kenji Michiue, Ignas Motuzis, Mark Robert James Elsegood, Carl Redshaw
Reaction of dibromosalicylic aldehyde and 2,6-diisopropylaniline, followed by sodium borohydride, and 2-chloromethylpyridine hydrochloride/triethylamine, and then with [VO(OiPr)3] led to [VO(L)(LH)] (where L = 2,6-iPr2C6H3N=CH-2-(O)-C6H2Br2-3,5) (1) as the major product, together with ca. 10% of [VO(OiPr)(L’)] (where L’ = {[(2-(O)C6H2Br2-3,5)CH2]2(μ-NC6H3-iPr2-2,6)} (2). Similar use of [VO(OEt)3] led to 1 and [VO(OEt)(L’)] (3). Use of excess [VO(OiPr)3] also led to the isolation of 2 plus [VO(L)(LH)] (4), which is related to 1 but with intramolecular H-bonding present. On changing the ratio of dibromosalicylic aldehyde and 2,6-diisopropylaniline to 2:1, further reaction with [VO(OiPr)3] afforded two polymorphs of [VO(L)2] (5 and 6). When 2,6-dimethylaniline was employed in a similar synthesis to LH, the product isolated with [VO(OiPr)3] was [VO(L’’)2] (7) (where L’’ = 2,6-Me2C6H3N=CH-2-(O)-C6H2Br2-3,5). The procedure employed for 1 was extended to 3,5-dichlorosalicylic aldehyde and afforded two polymorphs [VO(L)2] (8 τ = 0.07, 9 τ = 0.16) (where L = 2,6-iPr2C6H3CH=N-2-(O)-C6H2Cl2-3,5). Use of 3,5-diiodosalicylic aldehyde led to [VO(L)2]·MeCN (10·MeCN) (where L = 2,6-iPr2C6H3CH=N-2-(O)-C6H2I2-3,5). The intermediate compounds [2,6-iPr2C6H3N=CH-2-(OH)-C6H2Br2-3,5)] (LH), [2,6-iPr2C6H3NHCH2-2-(OH)-C6H2Br2-3,5)] (LH2) and the salt{[(2-(O)C6H2Br2-3,5)CH2][(2-(OH)C6H2Br2-3,5)CH2]2(μ-NC6H3-iPr2-2,6)}[Et3NH] ([L’H][Et3NH]) have also been characterized. Complexes 2, 3, 5, 8, and 10 have been screened as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and ẟ-valerolactone (ẟ-VL). Results revealed high conversions both in solution (130 oC) and as melts. Kinetic runs using ε-CL suggested 3, 5, and 8 performed best, whilst for ẟ-VL 8 out-performed the other systems; mostly linear polymers with end groups H/OH were formed. Complexes 1 and 2 have been screened as pre-catalysts for the polymerization of ethylene in the presence of EADC (ethylaluminium dichloride) and ETA (ethyl trichloroacetate) and for the co-polymerization of ethylene with propylene. Electron‑withdrawing bromo‑substituted complex 1 show markedly enhanced ethylene (co)polymerization activity and polymer molecular weight than previously reported Schiff‑base vanadium complexes without an electron‑withdrawing group. Complex 2 exhibited activity comparable to 1 and improved thermal stability relative to the previously reported pentavalent bisphenoxy complex without an electron‑withdrawing group.
{"title":"Vanadyl complexes supported by O,O-and N,O-chelate ligation: Structures and polymerization catalysis","authors":"Kaname Shibata, Kenji Michiue, Ignas Motuzis, Mark Robert James Elsegood, Carl Redshaw","doi":"10.1039/d6dt00387g","DOIUrl":"https://doi.org/10.1039/d6dt00387g","url":null,"abstract":"Reaction of dibromosalicylic aldehyde and 2,6-diisopropylaniline, followed by sodium borohydride, and 2-chloromethylpyridine hydrochloride/triethylamine, and then with [VO(OiPr)3] led to [VO(L)(LH)] (where L = 2,6-iPr2C6H3N=CH-2-(O)-C6H2Br2-3,5) (1) as the major product, together with ca. 10% of [VO(OiPr)(L’)] (where L’ = {[(2-(O)C6H2Br2-3,5)CH2]2(μ-NC6H3-iPr2-2,6)} (2). Similar use of [VO(OEt)3] led to 1 and [VO(OEt)(L’)] (3). Use of excess [VO(OiPr)3] also led to the isolation of 2 plus [VO(L)(LH)] (4), which is related to 1 but with intramolecular H-bonding present. On changing the ratio of dibromosalicylic aldehyde and 2,6-diisopropylaniline to 2:1, further reaction with [VO(OiPr)3] afforded two polymorphs of [VO(L)2] (5 and 6). When 2,6-dimethylaniline was employed in a similar synthesis to LH, the product isolated with [VO(OiPr)3] was [VO(L’’)2] (7) (where L’’ = 2,6-Me2C6H3N=CH-2-(O)-C6H2Br2-3,5). The procedure employed for 1 was extended to 3,5-dichlorosalicylic aldehyde and afforded two polymorphs [VO(L)2] (8 τ = 0.07, 9 τ = 0.16) (where L = 2,6-iPr2C6H3CH=N-2-(O)-C6H2Cl2-3,5). Use of 3,5-diiodosalicylic aldehyde led to [VO(L)2]·MeCN (10·MeCN) (where L = 2,6-iPr2C6H3CH=N-2-(O)-C6H2I2-3,5). The intermediate compounds [2,6-iPr2C6H3N=CH-2-(OH)-C6H2Br2-3,5)] (LH), [2,6-iPr2C6H3NHCH2-2-(OH)-C6H2Br2-3,5)] (LH2) and the salt{[(2-(O)C6H2Br2-3,5)CH2][(2-(OH)C6H2Br2-3,5)CH2]2(μ-NC6H3-iPr2-2,6)}[Et3NH] ([L’H][Et3NH]) have also been characterized. Complexes 2, 3, 5, 8, and 10 have been screened as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL) and ẟ-valerolactone (ẟ-VL). Results revealed high conversions both in solution (130 oC) and as melts. Kinetic runs using ε-CL suggested 3, 5, and 8 performed best, whilst for ẟ-VL 8 out-performed the other systems; mostly linear polymers with end groups H/OH were formed. Complexes 1 and 2 have been screened as pre-catalysts for the polymerization of ethylene in the presence of EADC (ethylaluminium dichloride) and ETA (ethyl trichloroacetate) and for the co-polymerization of ethylene with propylene. Electron‑withdrawing bromo‑substituted complex 1 show markedly enhanced ethylene (co)polymerization activity and polymer molecular weight than previously reported Schiff‑base vanadium complexes without an electron‑withdrawing group. Complex 2 exhibited activity comparable to 1 and improved thermal stability relative to the previously reported pentavalent bisphenoxy complex without an electron‑withdrawing group.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"2 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147454532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Phthalates are priority control pollutants with potential endocrine-disrupting and carcinogenic effects. Conventional catalytic cracking–oxidation technologies for treating such pollutants often face challenges including catalyst component leaching, active site deactivation, and unclear reaction mechanisms. In this study, a CeO2/Si-ZSM-5@Al-MS core–shell structured catalyst was successfully constructed by loading CeO2 onto an all-silica ZSM-5 core and encapsulating it with an aluminum-doped mesoporous silica shell. This catalyst exhibited excellent performance in the catalytic cracking of dibutyl phthalate (DBP), maintaining stable operation for 200 hours and effectively overcoming the technical bottlenecks of traditional processes. Combined density functional theory calculations and gas chromatography-mass spectrometry analysis systematically elucidated the decarboxylation pathway of phthalic anhydride over the CeO2/Si-ZSM-5 core, which is the hydrolysis product of DBP from the Al-MS shell. Furthermore, the integration of activated carbon thermal desorption with the cracking–oxidation technology exhibits significantly lower operating costs compared to existing DBP wastewater treatment technologies.
{"title":"Cracking–oxidation of dibutyl phthalate: core–shell catalyst, decarboxylation mechanism, and process cost","authors":"Guoqing Zhang, Tao Wei, Shangpu Zhuang, Jihai Tang, Mifen Cui, Xu Qiao, Zhuxiu Zhang","doi":"10.1039/d5dt02859k","DOIUrl":"https://doi.org/10.1039/d5dt02859k","url":null,"abstract":"Phthalates are priority control pollutants with potential endocrine-disrupting and carcinogenic effects. Conventional catalytic cracking–oxidation technologies for treating such pollutants often face challenges including catalyst component leaching, active site deactivation, and unclear reaction mechanisms. In this study, a CeO<small><sub>2</sub></small>/Si-ZSM-5@Al-MS core–shell structured catalyst was successfully constructed by loading CeO<small><sub>2</sub></small> onto an all-silica ZSM-5 core and encapsulating it with an aluminum-doped mesoporous silica shell. This catalyst exhibited excellent performance in the catalytic cracking of dibutyl phthalate (DBP), maintaining stable operation for 200 hours and effectively overcoming the technical bottlenecks of traditional processes. Combined density functional theory calculations and gas chromatography-mass spectrometry analysis systematically elucidated the decarboxylation pathway of phthalic anhydride over the CeO<small><sub>2</sub></small>/Si-ZSM-5 core, which is the hydrolysis product of DBP from the Al-MS shell. Furthermore, the integration of activated carbon thermal desorption with the cracking–oxidation technology exhibits significantly lower operating costs compared to existing DBP wastewater treatment technologies.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"82 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrochemical performance of α-MnO 2 cathodes in aqueous zinc-ion batteries is limited by their low electronic conductivity, structural instability due to Jahn-Teller distortion, and slow Zn²⁺ diffusion kinetics. Despite the ion doping can alleviate these issues, conventional 3d transition metal dopants usually only provide modest increments in electrochemical performance. In this work, we explore and demonstrate that ruthenium ions can act as an alternative dopant to address these challenges in a synergistic way. Ru 3+ /Ru 4+ ions have highly delocalized 4d orbitals and high-bondenergy Ru-O bonds, which can modify the electronic structure of α-MnO 2 effectively. As a result, the electrochemical performance of ruthenium-doped α-MnO₂ (RMO) cathode presents enhanced electrochemical performance with a specific capacity of 360.1 mAh g⁻ 1 at 0.1 A g⁻ 1 and good cycling stability with 76.7% capacity remaining after 5000 cycles at 3 A g⁻¹, which is significantly higher than pristine α-MnO₂. Density functional theory (DFT) calculations show that ruthenium doping can narrow the bandgap from 0.9296 eV to 0.6997 eV and decrease the Zn²⁺ diffusion energy barrier from 0.68 eV to 0.56 eV. This work demonstrates that 4d transition metal doping can fundamentally improve the physicochemical properties of MnO 2 and enhance its potential as a cathode material in aqueous zinc-ion batteries.
{"title":"4d Orbital Ruthenium Doping Enables High-Capacity and Stable α-MnO 2 Cathodes for Aqueous Zinc-Ion Batteries","authors":"Xinyang Zhang, Guochao Zhao, Xueyan Yang, Dewei Wang, Yuhong Chen, Chunping Hou","doi":"10.1039/d6dt00187d","DOIUrl":"https://doi.org/10.1039/d6dt00187d","url":null,"abstract":"The electrochemical performance of α-MnO 2 cathodes in aqueous zinc-ion batteries is limited by their low electronic conductivity, structural instability due to Jahn-Teller distortion, and slow Zn²⁺ diffusion kinetics. Despite the ion doping can alleviate these issues, conventional 3d transition metal dopants usually only provide modest increments in electrochemical performance. In this work, we explore and demonstrate that ruthenium ions can act as an alternative dopant to address these challenges in a synergistic way. Ru 3+ /Ru 4+ ions have highly delocalized 4d orbitals and high-bondenergy Ru-O bonds, which can modify the electronic structure of α-MnO 2 effectively. As a result, the electrochemical performance of ruthenium-doped α-MnO₂ (RMO) cathode presents enhanced electrochemical performance with a specific capacity of 360.1 mAh g⁻ 1 at 0.1 A g⁻ 1 and good cycling stability with 76.7% capacity remaining after 5000 cycles at 3 A g⁻¹, which is significantly higher than pristine α-MnO₂. Density functional theory (DFT) calculations show that ruthenium doping can narrow the bandgap from 0.9296 eV to 0.6997 eV and decrease the Zn²⁺ diffusion energy barrier from 0.68 eV to 0.56 eV. This work demonstrates that 4d transition metal doping can fundamentally improve the physicochemical properties of MnO 2 and enhance its potential as a cathode material in aqueous zinc-ion batteries.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"7 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Designing birefringent crystals with wide band gap presents significant challenges, especially within chalcogenide systems. Herein, motivated by the high structural anisotropy of thiourea, along with the ultraviolet compatibility and birefringence activity of halogenated tin(II)-based anionic groups, SnCl2[SC(NH2)2], a novel molecular crystal, was discovered. SnCl2[SC(NH2)2] was characterized by a bench-shaped molecule structure which is formed by the sharing of sulfur anion between a distorted SnCl2S trigonal pyramid and a planar π-conjugated thiourea unit. Through the synergistic interactions among multiple functional groups and the auxiliary regulation of hydrogen bonds, SnCl2[SC(NH2)2] succeeded in breaking the “3 eV wall” with a band gap of 3.362 eV and achieved a large birefringence of 0.20@546 nm, demonstrating a facile design strategy for the development of chalcogenides with dual optical enhancement.
{"title":"SnCl2[SC(NH2)2]: Lone-Pair and Hydrogen-Bonding Triggered Chromophore Assembling for Dual Optical Optimization","authors":"Xing-Yu Bi, Yuting Gao, Chenyuan Ma, Zhi Fang, Mei-Hong Duan","doi":"10.1039/d6dt00144k","DOIUrl":"https://doi.org/10.1039/d6dt00144k","url":null,"abstract":"Designing birefringent crystals with wide band gap presents significant challenges, especially within chalcogenide systems. Herein, motivated by the high structural anisotropy of thiourea, along with the ultraviolet compatibility and birefringence activity of halogenated tin(II)-based anionic groups, SnCl<small><sub>2</sub></small>[SC(NH<small><sub>2</sub></small>)<small><sub>2</sub></small>], a novel molecular crystal, was discovered. SnCl<small><sub>2</sub></small>[SC(NH<small><sub>2</sub></small>)<small><sub>2</sub></small>] was characterized by a bench-shaped molecule structure which is formed by the sharing of sulfur anion between a distorted SnCl<small><sub>2</sub></small>S trigonal pyramid and a planar π-conjugated thiourea unit. Through the synergistic interactions among multiple functional groups and the auxiliary regulation of hydrogen bonds, SnCl<small><sub>2</sub></small>[SC(NH<small><sub>2</sub></small>)<small><sub>2</sub></small>] succeeded in breaking the “3 eV wall” with a band gap of 3.362 eV and achieved a large birefringence of 0.20@546 nm, demonstrating a facile design strategy for the development of chalcogenides with dual optical enhancement.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"127 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bettina Diána Balogh, Giuseppe Di Natale, Giuseppe Pappalardo, Katalin Várnagy
Neurodegenerative taupathies are characterized by extracellular protein deposits of amyloid-β and intracellular aggregates of hyperphosphorylated tau in the brain. Great number of publications supports that essential metal ions (such as zinc and copper) play an important role in the development of neurodegeneration. The histidine imidazole rings are frequent metal binding sites in proteins and tau is relatively rich in this moiety. The 12 histidyl residues of the protein are well-separated and can be found in different chemical environment, hence their metal binding properties – at least slightly – differ. The comparison of the metal binding affinity of the His32 moiety from the N-terminal part of tau and the His329-His330 residues derived from the R3 domain revealed that copper(II) binding is more favourable to His32 than metal coordination by the adjacent imidazoles; while the His329-His330 moieties provide a binding site for zinc(II) ions at physiological pH. To further elucidate the metal binding ability of His32 and His329-His330 we studied the complex formation processes of a chimeric peptide (Ac-TMHQDNIHHKP-NH2) that contains the 30-34 residues (TMHQD) linked to the 327-332 residues (NIHHKP) in a single molecule (tau(30-34)(327-332)). The pH potentiometric, spectroscopic (UV-Vis, CD) and mass spectrometry studies on the copper(II) complexes of the peptide revealed that in equimolar samples predominantly mononuclear complexes with 1:1 stoichiometry are formed. At physiological pH and in alkaline samples the His32 imidazole nitrogen becomes the main, albeit not exclusive, anchoring group. The coordination mode of these copper(II) complexes can be described with the involvement of imidazole-N donor atoms and deprotonated amide functions. In the presence of zinc(II) ions only mononuclear species are formed. The results obtained for the mixed copper(II)-zinc(II) complexes support that the N-terminal imidazole nitrogen (His32) is the main anchoring group for copper(II) ions, while zinc(II) is accumulated at one of the adjacent histidyl residues if both metal ions are present in the solution at physiological pH. These findings are in agreement with the hypothesis that zinc(II), by binding to the R3 region, aggravate the aggregation processes of the R3 region and may increase the tau's toxicity.
{"title":"How copper(II) and zinc(II) bind to Tau protein and how might this promote aggregation?","authors":"Bettina Diána Balogh, Giuseppe Di Natale, Giuseppe Pappalardo, Katalin Várnagy","doi":"10.1039/d5dt03057a","DOIUrl":"https://doi.org/10.1039/d5dt03057a","url":null,"abstract":"Neurodegenerative taupathies are characterized by extracellular protein deposits of amyloid-β and intracellular aggregates of hyperphosphorylated tau in the brain. Great number of publications supports that essential metal ions (such as zinc and copper) play an important role in the development of neurodegeneration. The histidine imidazole rings are frequent metal binding sites in proteins and tau is relatively rich in this moiety. The 12 histidyl residues of the protein are well-separated and can be found in different chemical environment, hence their metal binding properties – at least slightly – differ. The comparison of the metal binding affinity of the His32 moiety from the N-terminal part of tau and the His329-His330 residues derived from the R3 domain revealed that copper(II) binding is more favourable to His32 than metal coordination by the adjacent imidazoles; while the His329-His330 moieties provide a binding site for zinc(II) ions at physiological pH. To further elucidate the metal binding ability of His32 and His329-His330 we studied the complex formation processes of a chimeric peptide (Ac-TMHQDNIHHKP-NH2) that contains the 30-34 residues (TMHQD) linked to the 327-332 residues (NIHHKP) in a single molecule (tau(30-34)(327-332)). The pH potentiometric, spectroscopic (UV-Vis, CD) and mass spectrometry studies on the copper(II) complexes of the peptide revealed that in equimolar samples predominantly mononuclear complexes with 1:1 stoichiometry are formed. At physiological pH and in alkaline samples the His32 imidazole nitrogen becomes the main, albeit not exclusive, anchoring group. The coordination mode of these copper(II) complexes can be described with the involvement of imidazole-N donor atoms and deprotonated amide functions. In the presence of zinc(II) ions only mononuclear species are formed. The results obtained for the mixed copper(II)-zinc(II) complexes support that the N-terminal imidazole nitrogen (His32) is the main anchoring group for copper(II) ions, while zinc(II) is accumulated at one of the adjacent histidyl residues if both metal ions are present in the solution at physiological pH. These findings are in agreement with the hypothesis that zinc(II), by binding to the R3 region, aggravate the aggregation processes of the R3 region and may increase the tau's toxicity.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"26 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report the selective hydroboration of ynones and enones catalyzed by DepNacnac stabilized magnesium hydride, Mg-1 [{LMgH}₂; L = DepNacnac = (DepNCMe)2CH; Dep = 2,6-Et2-C6H3] under mild conditions. A wide range of ynones and enones, including testosterone propionate, have been quantitatively converted into corresponding boronate esters. This magnesium-catalyzed method offers an efficient, eco-friendly alternative to traditional reductions of carbonyl compounds. The active catalyst {LMg–OCH(CH3)C≡C–Ph}2 (Mg-2) was isolated and characterized via 1H, 13C{1H} NMR and single crystal X-ray diffraction analyses. Based on the isolation of Mg-2 and stoichiometric reactions, a plausible catalytic cycle was established. The results highlight magnesium's potential in sustainable and selective organic transformations.
{"title":"Catalytic Hydroboration of α,β-Unsaturated Ketones Using β-Diketiminate Magnesium Hydride and Mechanistic Insights","authors":"Anubhab Das, Sayantan Mukhopadhyay, Sagrika Rajput, Sharanappa Nembenna","doi":"10.1039/d6dt00286b","DOIUrl":"https://doi.org/10.1039/d6dt00286b","url":null,"abstract":"We report the selective hydroboration of ynones and enones catalyzed by DepNacnac stabilized magnesium hydride, Mg-1 [{LMgH}₂; L = DepNacnac = (DepNCMe)2CH; Dep = 2,6-Et2-C6H3] under mild conditions. A wide range of ynones and enones, including testosterone propionate, have been quantitatively converted into corresponding boronate esters. This magnesium-catalyzed method offers an efficient, eco-friendly alternative to traditional reductions of carbonyl compounds. The active catalyst {LMg–OCH(CH3)C≡C–Ph}2 (Mg-2) was isolated and characterized via 1H, 13C{1H} NMR and single crystal X-ray diffraction analyses. Based on the isolation of Mg-2 and stoichiometric reactions, a plausible catalytic cycle was established. The results highlight magnesium's potential in sustainable and selective organic transformations.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"11 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the structure and reaction pathways of high-valent metal-oxo species in C-H bond activation and oxygen atom transfer reactions is of great importance for improving their reactivity. Herein, we examine the reactivity of heme-based Mn/Fe/Co-oxo porphyrin complexes supported by an axial 1,3-dimethylimidazole ligand with the substrates such as methane, 1,4-cyclohexadiene and dimethyl sulfide using density functional theory. Our calculations predicted quartet, triplet and doublet as the ground state for Mn, Fe and Co species, respectively. This study also reveals a reactivity trend of species Co > Fe > Mn during C-H bond activation and oxygen atom transfer reactions. Computed reaction profiles consistently identify the Co-oxo species as the most reactive, which establishing the reactivity order. Further, the formation of Co(III)-oxyl rather than a Co(IV)=O species in species 3 is supported by the pronounced spin density localized on the oxygen atom, orbital analysis, M-O bond length and stretching frequency trends. Non-covalent interactions and quantum theory of atoms in molecules analyses show stronger dispersive stabilization and greater Co-O bond polarization relative to the Mn and Fe analogues. Energy decomposition analysis further confirms more favorable interaction energies for the Co-O transition states. Our analysis demonstrates that the higher reactivity of species 3 arises from its uniquely polarized electronic structure, enhanced oxyl radical character, enhanced non-covalent transition state stabilization and stronger polarization in the Co-O bond. Overall, this work provides a new mechanistic understanding that moves beyond the traditional focus on spin state and oxyl radical character and offering definitive design principles for developing bioinspired catalysts capable of selective C-H bond and oxygen atom transfer functionalization.
了解C-H键活化和氧原子转移反应中高价金属-氧基团的结构和反应途径，对提高其反应活性具有重要意义。本文利用密度泛函理论研究了轴向1,3-二甲基咪唑配体支撑的血红素基Mn/Fe/ co -氧卟啉配合物与甲烷、1,4-环己二烯和二甲基硫化物等底物的反应性。我们的计算预测了锰、铁和钴的基态分别为四重态、三重态和双重态。本研究还揭示了Co >； Fe >； Mn在C-H键活化和氧原子转移反应中的反应性趋势。计算的反应谱一致地确定Co-oxo是最具反应性的，这建立了反应性顺序。此外，在物种3中形成Co(III)-氧而不是Co(IV)=O的物种是由定位在氧原子上的明显自旋密度、轨道分析、M-O键长度和拉伸频率趋势所支持的。分子分析中原子的非共价相互作用和量子理论表明，相对于Mn和Fe类似物，它们具有更强的色散稳定性和更大的Co-O键极化。能量分解分析进一步证实了Co-O过渡态具有更有利的相互作用能。我们的分析表明，物种3较高的反应活性源于其独特的极化电子结构、增强的氧自由基特征、增强的非共价过渡态稳定性和Co-O键的强极化。总的来说，这项工作提供了一种新的机制理解，超越了传统上对自旋态和氧自由基特征的关注，并为开发能够选择性C-H键和氧原子转移功能化的生物启发催化剂提供了明确的设计原则。
{"title":"Deciphering the Mechanistic Insights and Reactivity Trend of High-Valent Mn/Fe/Co-oxo Species toward C-H Bond Activation and Oxygen Atom Transfer","authors":"Mukhtar Ahmed, Manjeet Kumar, Mursaleem Ansari, Manoj K. Gupta, Azaj Ansari","doi":"10.1039/d5dt03104d","DOIUrl":"https://doi.org/10.1039/d5dt03104d","url":null,"abstract":"Understanding the structure and reaction pathways of high-valent metal-oxo species in C-H bond activation and oxygen atom transfer reactions is of great importance for improving their reactivity. Herein, we examine the reactivity of heme-based Mn/Fe/Co-oxo porphyrin complexes supported by an axial 1,3-dimethylimidazole ligand with the substrates such as methane, 1,4-cyclohexadiene and dimethyl sulfide using density functional theory. Our calculations predicted quartet, triplet and doublet as the ground state for Mn, Fe and Co species, respectively. This study also reveals a reactivity trend of species Co > Fe > Mn during C-H bond activation and oxygen atom transfer reactions. Computed reaction profiles consistently identify the Co-oxo species as the most reactive, which establishing the reactivity order. Further, the formation of Co(III)-oxyl rather than a Co(IV)=O species in species 3 is supported by the pronounced spin density localized on the oxygen atom, orbital analysis, M-O bond length and stretching frequency trends. Non-covalent interactions and quantum theory of atoms in molecules analyses show stronger dispersive stabilization and greater Co-O bond polarization relative to the Mn and Fe analogues. Energy decomposition analysis further confirms more favorable interaction energies for the Co-O transition states. Our analysis demonstrates that the higher reactivity of species 3 arises from its uniquely polarized electronic structure, enhanced oxyl radical character, enhanced non-covalent transition state stabilization and stronger polarization in the Co-O bond. Overall, this work provides a new mechanistic understanding that moves beyond the traditional focus on spin state and oxyl radical character and offering definitive design principles for developing bioinspired catalysts capable of selective C-H bond and oxygen atom transfer functionalization.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"8 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Montse Bazaga García, Rosario M. Pérez Colodrero, Álvaro Vílchez, Pascual Olivera Pastor, Juan Antonio Cecilia, Lukasz Kurowski, Jan Kazimierz Zaręba, Aurelio Cabeza Díaz
Zirconium phosphonates combine the thermal robustness of Zr–O frameworks with the rich functionality of organophosphonic linkers, making them attractive for both energy-related and catalytic applications. Here we report three new crystalline Zr(IV) phosphonates built from 5-(dihydroxyphosphoryl)-isophthalic acid (PiPhtA), 5-(dihydroxyphosphoryl)-nicotinic acid (PNA) and benzene-1,2,3-triyltris(methylenephosphonic acid) (BTTMPA). Phase-pure Zr[(HO3P-C6H3-(COOH)2)2(X)2]·6H2O (X = F-/OH-) (Zr-PiPhtA), Zr(O3P-NH+-C5H3-COOH)2F2 (Zr-PNA) and Zr[(H2O3PCH2)(O3PCH2)2-C6H3]·H2O (Zr-BTTMP) were obtained under mild solvothermal conditions and characterized by synchrotron powder X-ray diffraction, pair-distribution-function (PDF) analysis, solid-state NMR and thermogravimetry. The crystal structures of 1D Zr-PNA (P21/c) and 3D Zr-BTTMP (P21/a) were solved ab initio from powder diffraction data, while combined structural X-ray diffraction and PDF analyses together with ammonia adsorption suggest that nanocrystalline Zr-PiPhtA exhibit features resembling those of analogous Ca-PiPhtA derivative and Zr-BTTMP. Given that all of them exhibit characteristic adequate for facilitating proton transfer pathways, a study of proton conductivity was undertaken. Under 95 % relative humidity, bulk proton conductivities reach 1.2 × 10-3 S cm-1 (Zr-BTTMP) at 80 °C. On exposure to NH3 vapour, the conductivity of Zr-PiPhtA and Zr-PNA increased by almost one order of magnitude, up to 3.2 × 10-3 S cm-1 at 80 °C for Zr-PiPhtA, highlighting the decisive role of ammonium-assisted proton hopping. The same acid sites that promote proton mobility also endow the materials with bifunctional catalytic behavior. In the one-pot cascade upgrading of furfural, Zr-PiPhtA afforded the highest overall conversions benefiting from nanocrystalline morphology and a higher density of strong Brønsted acid sites.
{"title":"Structural Characterization, Proton Conductivity and Furfural Catalysis of Novel Polyfunctional Zirconium Phosphonates","authors":"Montse Bazaga García, Rosario M. Pérez Colodrero, Álvaro Vílchez, Pascual Olivera Pastor, Juan Antonio Cecilia, Lukasz Kurowski, Jan Kazimierz Zaręba, Aurelio Cabeza Díaz","doi":"10.1039/d5dt02947c","DOIUrl":"https://doi.org/10.1039/d5dt02947c","url":null,"abstract":"Zirconium phosphonates combine the thermal robustness of Zr–O frameworks with the rich functionality of organophosphonic linkers, making them attractive for both energy-related and catalytic applications. Here we report three new crystalline Zr(IV) phosphonates built from 5-(dihydroxyphosphoryl)-isophthalic acid (PiPhtA), 5-(dihydroxyphosphoryl)-nicotinic acid (PNA) and benzene-1,2,3-triyltris(methylenephosphonic acid) (BTTMPA). Phase-pure Zr[(HO3P-C6H3-(COOH)2)2(X)2]·6H2O (X = F-/OH-) (Zr-PiPhtA), Zr(O3P-NH+-C5H3-COOH)2F2 (Zr-PNA) and Zr[(H2O3PCH2)(O3PCH2)2-C6H3]·H2O (Zr-BTTMP) were obtained under mild solvothermal conditions and characterized by synchrotron powder X-ray diffraction, pair-distribution-function (PDF) analysis, solid-state NMR and thermogravimetry. The crystal structures of 1D Zr-PNA (P21/c) and 3D Zr-BTTMP (P21/a) were solved ab initio from powder diffraction data, while combined structural X-ray diffraction and PDF analyses together with ammonia adsorption suggest that nanocrystalline Zr-PiPhtA exhibit features resembling those of analogous Ca-PiPhtA derivative and Zr-BTTMP. Given that all of them exhibit characteristic adequate for facilitating proton transfer pathways, a study of proton conductivity was undertaken. Under 95 % relative humidity, bulk proton conductivities reach 1.2 × 10-3 S cm-1 (Zr-BTTMP) at 80 °C. On exposure to NH3 vapour, the conductivity of Zr-PiPhtA and Zr-PNA increased by almost one order of magnitude, up to 3.2 × 10-3 S cm-1 at 80 °C for Zr-PiPhtA, highlighting the decisive role of ammonium-assisted proton hopping. The same acid sites that promote proton mobility also endow the materials with bifunctional catalytic behavior. In the one-pot cascade upgrading of furfural, Zr-PiPhtA afforded the highest overall conversions benefiting from nanocrystalline morphology and a higher density of strong Brønsted acid sites.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"55 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147393522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David Rezazgui, Ivana Císařová, Petr Štěpnička, Jiří Schulz
A series of hybrid, ferrocene-based phosphines bearing additional amine substituents has been synthesized and evaluated in gold catalysis. The series includes 1,1′- and 1,2-disubstituted phosphinoferrocene donors with cyclic or acyclic amine groups (morpholine, thiomorpholine, and dimethylamine) and various substituents on the phosphorus atom (phenyl, cyclohexyl, and 2-furyl). The compounds were prepared using two complementary routes: (1) alkylation of a sulfide-protected phosphine–amine intermediate and (2) copper-catalyzed electrophilic amination followed by a lithiation/phosphinylation step. The corresponding chlorogold(I) complexes [AuCl(L-κP)], obtained in high yields and structurally characterized, were evaluated as precatalysts in intramolecular cyclization of N-propargylbenzamide into 4,5-dihydro-5-methylene-2-phenyloxazole and oxidative cyclization of phenylacetylene with acetonitrile (using pyridine N-oxide as the oxidant) to 2-methyl-5-phenyl-1,3-oxazole. Catalytic studies revealed that the nature of the amine and phosphine substituents strongly influence the catalyst performance. Compared with their 1,2-disubstituted (homoannular) analogs, the complexes obtained from 1,1′-disubstituted (heteroannular) ligands generally exhibited faster reaction rates. In addition, a specific structural distortion of the ferrocene unit comprising the bending of the N-bound cyclopentadienyl carbon atom from the ring plane was detected in the structures of compounds bearing an amine group as the sole substituent on the cyclopentadienyl ring. This distortion was rationalized using DFT calculations as a consequence of the mesomeric effect of the amine moiety, which affects the electron distribution in the cyclopentadienyl ring.
{"title":"Synthesis of hybrid phosphinoferrocene ligands bearing amine pendants and catalytic evaluation of their gold(I) complexes","authors":"David Rezazgui, Ivana Císařová, Petr Štěpnička, Jiří Schulz","doi":"10.1039/d6dt00321d","DOIUrl":"https://doi.org/10.1039/d6dt00321d","url":null,"abstract":"A series of hybrid, ferrocene-based phosphines bearing additional amine substituents has been synthesized and evaluated in gold catalysis. The series includes 1,1′- and 1,2-disubstituted phosphinoferrocene donors with cyclic or acyclic amine groups (morpholine, thiomorpholine, and dimethylamine) and various substituents on the phosphorus atom (phenyl, cyclohexyl, and 2-furyl). The compounds were prepared using two complementary routes: (1) alkylation of a sulfide-protected phosphine–amine intermediate and (2) copper-catalyzed electrophilic amination followed by a lithiation/phosphinylation step. The corresponding chlorogold(I) complexes [AuCl(L-κP)], obtained in high yields and structurally characterized, were evaluated as precatalysts in intramolecular cyclization of N-propargylbenzamide into 4,5-dihydro-5-methylene-2-phenyloxazole and oxidative cyclization of phenylacetylene with acetonitrile (using pyridine N-oxide as the oxidant) to 2-methyl-5-phenyl-1,3-oxazole. Catalytic studies revealed that the nature of the amine and phosphine substituents strongly influence the catalyst performance. Compared with their 1,2-disubstituted (homoannular) analogs, the complexes obtained from 1,1′-disubstituted (heteroannular) ligands generally exhibited faster reaction rates. In addition, a specific structural distortion of the ferrocene unit comprising the bending of the N-bound cyclopentadienyl carbon atom from the ring plane was detected in the structures of compounds bearing an amine group as the sole substituent on the cyclopentadienyl ring. This distortion was rationalized using DFT calculations as a consequence of the mesomeric effect of the amine moiety, which affects the electron distribution in the cyclopentadienyl ring.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"5 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147384163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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