Traditional dehydrogenation of amines involves the transfer of hydrogen molecule(s) from a substrate to an acceptor. In acceptorless dehydrogenation, hydrogen gas is liberated without an oxidant, providing an efficient synthetic method. Acceptorless dehydrogenation of primary amines to nitriles without using an oxidant or hydrogen acceptor is significant yet challenging. Herein, we present efficient Ru-based catalysts capable of carrying out such a transformation with hydrogen gas as the only by-product. A new class of air and moisture-stable ruthenium-hydride complexes (1 – 4) of amide-acid/ester-based ligands have been synthesized and characterized. Crystal structures of two representative complexes, 2 and 3, illustrate the bidentate N-O coordination mode of the ligands. At the same time, additional binding sites are occupied by one hydride, one CO, and two PPh3 co-ligands. The catalytic behavior of these complexes is explored towards the oxidant-free, acceptorless, and selective dehydrogenation of primary and secondary amines affording nitriles and imines, respectively. Among four Ru(II) complexes, complex 2 showed the best catalytic activity for the dehydrogenation of amines. A wide variety of both primary and secondary amines were utilized to explore the substrate scope. The catalytic system tolerated both electron-withdrawing and electron-releasing substituents on amine substrates. Various control experiments and mechanistic studies were carried out to support the dehydrogenation of amines by using complex 2 as a representative catalyst.
{"title":"Acceptorless oxidant-free dehydrogenation of amines catalyzed by Ru-hydride complexes of amide-acid/ester ligands","authors":"Rajeev Gupta, Samanta Yadav","doi":"10.1039/d4dt03201b","DOIUrl":"https://doi.org/10.1039/d4dt03201b","url":null,"abstract":"Traditional dehydrogenation of amines involves the transfer of hydrogen molecule(s) from a substrate to an acceptor. In acceptorless dehydrogenation, hydrogen gas is liberated without an oxidant, providing an efficient synthetic method. Acceptorless dehydrogenation of primary amines to nitriles without using an oxidant or hydrogen acceptor is significant yet challenging. Herein, we present efficient Ru-based catalysts capable of carrying out such a transformation with hydrogen gas as the only by-product. A new class of air and moisture-stable ruthenium-hydride complexes (1 – 4) of amide-acid/ester-based ligands have been synthesized and characterized. Crystal structures of two representative complexes, 2 and 3, illustrate the bidentate N-O coordination mode of the ligands. At the same time, additional binding sites are occupied by one hydride, one CO, and two PPh3 co-ligands. The catalytic behavior of these complexes is explored towards the oxidant-free, acceptorless, and selective dehydrogenation of primary and secondary amines affording nitriles and imines, respectively. Among four Ru(II) complexes, complex 2 showed the best catalytic activity for the dehydrogenation of amines. A wide variety of both primary and secondary amines were utilized to explore the substrate scope. The catalytic system tolerated both electron-withdrawing and electron-releasing substituents on amine substrates. Various control experiments and mechanistic studies were carried out to support the dehydrogenation of amines by using complex 2 as a representative catalyst.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"208 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385782","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}
A series of antimony(III) triaryl corroles bearing different numbers of meso-pentafluorophenyl substituents were synthesized and evaluated as catalysts for electrocatalytic hydrogen evolution. The introduction of electron-withdrawing pentafluorophenyl to the corrole macrocycle led to a significant boost in electro-catalytic hydrogen evolution reaction (HER) activity both in organic and aqueous media, highlighting the tunability of these complexes for enhanced catalytic activity
{"title":"Substituent effect on the ligand-centred electrocatalytic hydrogen evolution of antimony(III) corroles","authors":"Qing-Hua Yu, Yu-Fei Li, Xu-You Cao, Liang-Hong Liu, Junying Chen, Li-Ping Si, Hai-Yang Liu","doi":"10.1039/d4dt03178d","DOIUrl":"https://doi.org/10.1039/d4dt03178d","url":null,"abstract":"A series of antimony(III) triaryl corroles bearing different numbers of meso-pentafluorophenyl substituents were synthesized and evaluated as catalysts for electrocatalytic hydrogen evolution. The introduction of electron-withdrawing pentafluorophenyl to the corrole macrocycle led to a significant boost in electro-catalytic hydrogen evolution reaction (HER) activity both in organic and aqueous media, highlighting the tunability of these complexes for enhanced catalytic activity","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"47 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385652","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}
Guoqi Zhang, Michelle C. Neary, Qinguo Zhang, Xiao Chen, Hyunjeong Kim, Ashley Kaswer, Maisha Ahmed, Shu-Yuan Cheng, Jason M. Rauceo
Complexes of non-radioactive indium(III) with 2,2´;6´,2´´-terpyridine (tpy) ligands are rarely explored despite the popularity of tpy as a strong chelating ligand backbone. Herein, three mononuclear indium(III) complexes (In-1, In-2 and In-3) of tpy and its 4´-Cl and 4´-pyridyl derivatives have been synthesized and structurally characterized. While the crystal structure of In-1 has been previously studied, In-2 and In-3 were isolated and characterized for the first time. Two different polymorphs of In-2 were observed by simply varying the concentration of reactions. Molecules of In-3 were determined by X-ray crystallography to adopt the same mononuclear coordination mode as found in In-1 and In-2, while the remaining 4´-pyridyl ring was uncoordinated. Bioactivity studies revealed that indium(III) complexes In-1, In-2, and In-3 were fungicidal against the human fungal pathogen, Candida albicans, and several non-albicans Candida species. Moreover, the cytotoxicity studies showed these compounds were remarkably antiproliferative against human breast cancer cells (MCF-7 and MDA-MB 468).
{"title":"Indium(III)-terpyridine complexes: synthesis, structures and remarkable antifungal and anticancer activities","authors":"Guoqi Zhang, Michelle C. Neary, Qinguo Zhang, Xiao Chen, Hyunjeong Kim, Ashley Kaswer, Maisha Ahmed, Shu-Yuan Cheng, Jason M. Rauceo","doi":"10.1039/d4dt03492a","DOIUrl":"https://doi.org/10.1039/d4dt03492a","url":null,"abstract":"Complexes of non-radioactive indium(III) with 2,2´;6´,2´´-terpyridine (tpy) ligands are rarely explored despite the popularity of tpy as a strong chelating ligand backbone. Herein, three mononuclear indium(III) complexes (In-1, In-2 and In-3) of tpy and its 4´-Cl and 4´-pyridyl derivatives have been synthesized and structurally characterized. While the crystal structure of In-1 has been previously studied, In-2 and In-3 were isolated and characterized for the first time. Two different polymorphs of In-2 were observed by simply varying the concentration of reactions. Molecules of In-3 were determined by X-ray crystallography to adopt the same mononuclear coordination mode as found in In-1 and In-2, while the remaining 4´-pyridyl ring was uncoordinated. Bioactivity studies revealed that indium(III) complexes In-1, In-2, and In-3 were fungicidal against the human fungal pathogen, Candida albicans, and several non-albicans Candida species. Moreover, the cytotoxicity studies showed these compounds were remarkably antiproliferative against human breast cancer cells (MCF-7 and MDA-MB 468).","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"28 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385653","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}
Ahmed M. Mansour, Mohamed M. Arafa, Yara S. Hegazy, Muhammed S. Sadek, Hadeer H. Ibrahim, Yomna S. Abdullah, Ola R. Shehab
Iridium(III) complexes, particularly those with piano-stool structures, have drawn a lot of interest recently as possible anticancer drugs. These complexes, which have displayed enhanced cytotoxicity and cytoselectivity compared with clinically approved drugs like cisplatin, oxaliplatin, and carboplatin, hold promising prospects for further anticancer research. Our review aims to explore the complex interplay between cytotoxic properties, cellular uptake efficiency, and intracellular distribution properties of this class of Ir(III) complexes, considering the variation of the coordination site atoms. We provide an overview of the majority of research on mono- and polynunclear half-sandwich Ir(III) complexes with mono- and bidentate ligands, focusing on the impact of altering the leaving group, tethers, substituents on the cyclopentadienyl ring and ligand, spacers, and counter ions on the cytotoxicity and mode of action.
{"title":"A comprehensive survey of cytotoxic active half-sandwich Ir(III) complexes: structural perspective, and mechanism of action","authors":"Ahmed M. Mansour, Mohamed M. Arafa, Yara S. Hegazy, Muhammed S. Sadek, Hadeer H. Ibrahim, Yomna S. Abdullah, Ola R. Shehab","doi":"10.1039/d4dt03219e","DOIUrl":"https://doi.org/10.1039/d4dt03219e","url":null,"abstract":"Iridium(<small>III</small>) complexes, particularly those with piano-stool structures, have drawn a lot of interest recently as possible anticancer drugs. These complexes, which have displayed enhanced cytotoxicity and cytoselectivity compared with clinically approved drugs like cisplatin, oxaliplatin, and carboplatin, hold promising prospects for further anticancer research. Our review aims to explore the complex interplay between cytotoxic properties, cellular uptake efficiency, and intracellular distribution properties of this class of Ir(<small>III</small>) complexes, considering the variation of the coordination site atoms. We provide an overview of the majority of research on mono- and polynunclear half-sandwich Ir(<small>III</small>) complexes with mono- and bidentate ligands, focusing on the impact of altering the leaving group, tethers, substituents on the cyclopentadienyl ring and ligand, spacers, and counter ions on the cytotoxicity and mode of action.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"22 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385595","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}
T. Nivedya, Rishav Das, Selva Kumar Ramasamy, shanooja shanavas, R. Bhaskar, Mujthaba Aatif A, Chandrapaul Mukherjee, Riona Roy, Jhimli Sengupta, Bipasha Bose, Ashok S.K. Kumar, Priyankar Paira
The study investigated the impact of benzodipyridophenazine-based Ru(II) and Ir(III) complexes (Ru1, Ru2, Ir1, and Ir2) on their anticancer activity. Metal complexes displayed three significant absorption bands because of intra-ligand charge transfer (ILCT), ligand-to-ligand charge transfer (LLCT), and metal-to-ligand charge transfer (MLCT). Binding studies with biomolecules has been performed with the complexes along with the ligand, and it was found that after attaching with Ru(II)/Ir(III),properties of the ligands has enhanced. In vitro, screening identified that, complex [(η5-Cp*)IrIIICl(κ2-N, N-benzo[i]dipyrido[3,2-a:2',3'-c])phenazine (Ir1) exhibited the highest potency and selectivity (IC50 ~ 2.14 µM, PI > 13) under yellow light irradiation. The photo-toxicity trend was Ir1>Ru1>Ir2>>Ru2, which was found to be directly correlated with the release of singlet oxygen quantum yield (1O2). Chloro-substituted complexes (Ir1, Ru1) are effective for hypoxic tumor treatment, particularly Ir1 which can generate high amounts of reactive oxygen species (ROS, Type I PDT) in cells under photo irradiation. The high value of fluorescence quantum yield (fφ = 0.26) and significant emission at λ = 571 nm of Ir1 certainly helps in a bio-imaging application. Colocalisation study and DCFDA studies with Ir1 revealed that, it can accumulates in the mitochondria, leading to the depolarization of the mitochondrial membrane. These studies confirms the complex Ir1 is a promising candidate for TNBC treatment in hypoxic tumors, with efficacy comparable to the current PDT drug, photofrin.
{"title":"The Role of Ancillary Ligands on Benzodipyridophenazine Based Ru(II)/Ir(III) Complexes for Dark and Light Toxicity against TNBC Cells¥","authors":"T. Nivedya, Rishav Das, Selva Kumar Ramasamy, shanooja shanavas, R. Bhaskar, Mujthaba Aatif A, Chandrapaul Mukherjee, Riona Roy, Jhimli Sengupta, Bipasha Bose, Ashok S.K. Kumar, Priyankar Paira","doi":"10.1039/d4dt03456b","DOIUrl":"https://doi.org/10.1039/d4dt03456b","url":null,"abstract":"The study investigated the impact of benzodipyridophenazine-based Ru(II) and Ir(III) complexes (Ru1, Ru2, Ir1, and Ir2) on their anticancer activity. Metal complexes displayed three significant absorption bands because of intra-ligand charge transfer (ILCT), ligand-to-ligand charge transfer (LLCT), and metal-to-ligand charge transfer (MLCT). Binding studies with biomolecules has been performed with the complexes along with the ligand, and it was found that after attaching with Ru(II)/Ir(III),properties of the ligands has enhanced. In vitro, screening identified that, complex [(η5-Cp*)IrIIICl(κ2-N, N-benzo[i]dipyrido[3,2-a:2',3'-c])phenazine (Ir1) exhibited the highest potency and selectivity (IC50 ~ 2.14 µM, PI > 13) under yellow light irradiation. The photo-toxicity trend was Ir1>Ru1>Ir2>>Ru2, which was found to be directly correlated with the release of singlet oxygen quantum yield (1O2). Chloro-substituted complexes (Ir1, Ru1) are effective for hypoxic tumor treatment, particularly Ir1 which can generate high amounts of reactive oxygen species (ROS, Type I PDT) in cells under photo irradiation. The high value of fluorescence quantum yield (fφ = 0.26) and significant emission at λ = 571 nm of Ir1 certainly helps in a bio-imaging application. Colocalisation study and DCFDA studies with Ir1 revealed that, it can accumulates in the mitochondria, leading to the depolarization of the mitochondrial membrane. These studies confirms the complex Ir1 is a promising candidate for TNBC treatment in hypoxic tumors, with efficacy comparable to the current PDT drug, photofrin.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"30 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385654","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}
Mononuclear rare-earth metal alkyl complexes with an anilido-imino ligand were synthesized and characterized, and their catalytic ability for the formation of dihydroquinazolines and isoindolines from nitriles and amines was investigated. Reactions of rare-earth-metal trialkyl complexes RE(CH2SiMe3)3(THF)2 with the proligand HL (L= (o-(NHDipp)C6H4CH=N(CH2)2NC4H8, Dipp = 2,6-iPr2C6H3) in toluene afforded tridentate anilido-imino rare-earth metal dialkyl complexes LRE(CH2SiMe3)2 (RE = Gd (1a), Y (1b), Yb (1c), Lu (1d)) in good yields. Further study showed that these rare-earth metal catalysts could fulfill tandem addition/cyclization between ortho imine-functionalized benzonitriles and aromatic amines to afford 2,3-dihydroquinazolinimines for the first time. In addition, the catalysts are well applied to the reaction of substituted phthalonitriles with primary aromatic and aliphatic amines, producing various 1, 3-diimino isoindolines in moderate to excellent yields. During the process of mechanism study, two anilido yttrium complexes LY(NHPh)2(THF) (7b) and LY(NHDipp)2 (8b) were isolated by the reaction of 1b with aniline and 2,6-diisopropylaniline, respectively as well as their catalytic performance.
{"title":"Synthesis of 2,3-dihydroquinazolinimines and 1,3-diimino isoindolines catalyzed by rare earth metal alkyl complexes through tandem addition/cyclization of nitriles with amines","authors":"Dianjun Guo, Jinqiang He, Qingbing Yuan, Shuangliu Zhou, Xiancui Zhu","doi":"10.1039/d5dt00106d","DOIUrl":"https://doi.org/10.1039/d5dt00106d","url":null,"abstract":"Mononuclear rare-earth metal alkyl complexes with an anilido-imino ligand were synthesized and characterized, and their catalytic ability for the formation of dihydroquinazolines and isoindolines from nitriles and amines was investigated. Reactions of rare-earth-metal trialkyl complexes RE(CH2SiMe3)3(THF)2 with the proligand HL (L= (o-(NHDipp)C6H4CH=N(CH2)2NC4H8, Dipp = 2,6-iPr2C6H3) in toluene afforded tridentate anilido-imino rare-earth metal dialkyl complexes LRE(CH2SiMe3)2 (RE = Gd (1a), Y (1b), Yb (1c), Lu (1d)) in good yields. Further study showed that these rare-earth metal catalysts could fulfill tandem addition/cyclization between ortho imine-functionalized benzonitriles and aromatic amines to afford 2,3-dihydroquinazolinimines for the first time. In addition, the catalysts are well applied to the reaction of substituted phthalonitriles with primary aromatic and aliphatic amines, producing various 1, 3-diimino isoindolines in moderate to excellent yields. During the process of mechanism study, two anilido yttrium complexes LY(NHPh)2(THF) (7b) and LY(NHDipp)2 (8b) were isolated by the reaction of 1b with aniline and 2,6-diisopropylaniline, respectively as well as their catalytic performance.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"78 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385655","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}
This study investigates the interaction of ciprofloxacin (CIP) with three different ionic liquids (ILs) with distinct cationic residues (pyrrolidinium, IL1 vs imidazolium, IL2, with bis (trifluoromethylsulfonyl)imide as counter anion and counter anions (bis (trifluoromethylsulfonyl)imide, IL2 vs hexafluorophosphate, IL3 with imidazolium as cationic residue) in the aqueous environment. A series of spectroscopic studies have been performed to elucidate the role of ILs in optical properties as well as aggregation behavior of CIP. The fluorescence quenching experiment indicated that IL with pyrrolidinium residue showed stronger binding with CIP, while bis (trifluoromethylsulfonyl)imide would be the preferred choice of anion. These quenching effects might be attributed to complex formation mediated by charge-pair and cation−π interactions, along with hydrogen bonding. The Stern−Volmer analysis confirmed a static quenching mechanism, with binding constants (Kb) reflecting the stronger affinity of IL1 due to hydrophobic butyl group and flexible pyrrolidinium cation, resulting formation of larger aggregates. In contrast, the imidazolium residue in IL2 facilitated π−π and hydrogen-bond interactions, disrupting CIP aggregation and resulting in smaller clusters. The polarizable nature of bis(trifluoromethylsulfonyl)imide along with hydrogen bond accepting nature enable stronger binding of ILs to CIP compared to hexafluorophosphate containing ILs. Further studies indicated that pH 6 is optimum for CIP-IL interactions, where CIP remained in zwitterionic form. Increased temperature and ionic strength diminished quenching efficiency, consistent with the reduced stability of CIP-IL complexes under such conditions.
{"title":"Unravelling Optical Properties and Self-Assembly Behavior of Ciprofloxacin in Ionic Liquid Environments: Probing the Role of Cationic Residues and Counter Anions","authors":"Swapan Patra, Nilanjan Dey","doi":"10.1039/d5dt00081e","DOIUrl":"https://doi.org/10.1039/d5dt00081e","url":null,"abstract":"This study investigates the interaction of ciprofloxacin (CIP) with three different ionic liquids (ILs) with distinct cationic residues (pyrrolidinium, IL1 vs imidazolium, IL2, with bis (trifluoromethylsulfonyl)imide as counter anion and counter anions (bis (trifluoromethylsulfonyl)imide, IL2 vs hexafluorophosphate, IL3 with imidazolium as cationic residue) in the aqueous environment. A series of spectroscopic studies have been performed to elucidate the role of ILs in optical properties as well as aggregation behavior of CIP. The fluorescence quenching experiment indicated that IL with pyrrolidinium residue showed stronger binding with CIP, while bis (trifluoromethylsulfonyl)imide would be the preferred choice of anion. These quenching effects might be attributed to complex formation mediated by charge-pair and cation−π interactions, along with hydrogen bonding. The Stern−Volmer analysis confirmed a static quenching mechanism, with binding constants (Kb) reflecting the stronger affinity of IL1 due to hydrophobic butyl group and flexible pyrrolidinium cation, resulting formation of larger aggregates. In contrast, the imidazolium residue in IL2 facilitated π−π and hydrogen-bond interactions, disrupting CIP aggregation and resulting in smaller clusters. The polarizable nature of bis(trifluoromethylsulfonyl)imide along with hydrogen bond accepting nature enable stronger binding of ILs to CIP compared to hexafluorophosphate containing ILs. Further studies indicated that pH 6 is optimum for CIP-IL interactions, where CIP remained in zwitterionic form. Increased temperature and ionic strength diminished quenching efficiency, consistent with the reduced stability of CIP-IL complexes under such conditions.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"14 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385657","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}
Connor K. Holiski, Tara Mastren, Jennifer A. Shusterman
Separating trivalent f-block elements remains a central challenge due to their similar ionic radii and chemical behaviors. Historically, these separations have been achieved using single extractants, either alone or in combination with ion exchange chromatography. However, recent studies, including this work, have explored the potential of using synergic combinations of multiple extractants to enhance extraction and separation efficiencies for trivalent actinide separations. This study investigated synergic solvent extraction (SX) systems for extracting and separating americium and curium using three neutral organophosphorus ligands: octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine (CMPO), dibutyl N,N-diethylcarbamylmethylenephosphonate (DBDECMP), and dihexyl N,N-diethylcarbamylmethylenephosphonate (DHDECMP), combined with either 2-thenoyltrifluoroacetone (HTTA, pKa = 6.25) or 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP, pKa = 3.95). Distribution ratios (D) were determined for 241Am3+ and 242Cm3+ as functions of nitric acid pH using 1,2-dichloroethane as the solvent. The combination of these ligands resulted in varying degrees of synergy as demonstrated by their synergic extraction enhancement coefficients (SEC). A maximum separation factor (SFAm/Cm) of 2.65 ± 0.21 was achieved with 0.05 M HTTA and 0.05 M DBDECMP at pH 2.50. This extractant combination was impregnated into an inert macroporous support at various ligand ratios using rotary evaporator methods to produce novel extraction chromatographic (EXC) resins. Various parameters affecting the adsorption of 241Am3+ and 242Cm3+ onto EXC resins, such as solution pH, ionic strength, contact time, γ-irradiation dose, and temperature, were studied. Metal extraction and synergism were retained upon conversion to EXC resins, with increasing extraction observed at higher pH levels. Thermodynamic studies showed increased adsorption and decreased Gibbs free energy (ΔG) with rising temperature. Kinetic investigations indicated rapid and consistent uptake after 10 minutes. The EXC resins exhibited excellent metal retention in preliminary column experiments, demonstrating a promising potential to separate americium and curium with a maximum decontamination factor of 88. Overall, this work successfully demonstrated the identification and conversion of synergic SX systems into novel synergic EXC resins for adjacent trivalent actinide separations.
{"title":"The synergic effect of neutral organophosphorus ligands combined with acidic β-diketones for the extraction and separation of trivalent actinides","authors":"Connor K. Holiski, Tara Mastren, Jennifer A. Shusterman","doi":"10.1039/d4dt03310h","DOIUrl":"https://doi.org/10.1039/d4dt03310h","url":null,"abstract":"Separating trivalent f-block elements remains a central challenge due to their similar ionic radii and chemical behaviors. Historically, these separations have been achieved using single extractants, either alone or in combination with ion exchange chromatography. However, recent studies, including this work, have explored the potential of using synergic combinations of multiple extractants to enhance extraction and separation efficiencies for trivalent actinide separations. This study investigated synergic solvent extraction (SX) systems for extracting and separating americium and curium using three neutral organophosphorus ligands: octyl (phenyl)-<em>N</em>,<em>N</em>-diisobutylcarbamoylmethylphosphine (CMPO), dibutyl <em>N</em>,<em>N</em>-diethylcarbamylmethylenephosphonate (DBDECMP), and dihexyl <em>N</em>,<em>N</em>-diethylcarbamylmethylenephosphonate (DHDECMP), combined with either 2-thenoyltrifluoroacetone (HTTA, p<em>K</em><small><sub>a</sub></small> = 6.25) or 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP, p<em>K</em><small><sub>a</sub></small> = 3.95). Distribution ratios (<em>D</em>) were determined for <small><sup>241</sup></small>Am<small><sup>3+</sup></small> and <small><sup>242</sup></small>Cm<small><sup>3+</sup></small> as functions of nitric acid pH using 1,2-dichloroethane as the solvent. The combination of these ligands resulted in varying degrees of synergy as demonstrated by their synergic extraction enhancement coefficients (SEC). A maximum separation factor (SF<small><sub>Am/Cm</sub></small>) of 2.65 ± 0.21 was achieved with 0.05 M HTTA and 0.05 M DBDECMP at pH 2.50. This extractant combination was impregnated into an inert macroporous support at various ligand ratios using rotary evaporator methods to produce novel extraction chromatographic (EXC) resins. Various parameters affecting the adsorption of <small><sup>241</sup></small>Am<small><sup>3+</sup></small> and <small><sup>242</sup></small>Cm<small><sup>3+</sup></small> onto EXC resins, such as solution pH, ionic strength, contact time, γ-irradiation dose, and temperature, were studied. Metal extraction and synergism were retained upon conversion to EXC resins, with increasing extraction observed at higher pH levels. Thermodynamic studies showed increased adsorption and decreased Gibbs free energy (Δ<em>G</em>) with rising temperature. Kinetic investigations indicated rapid and consistent uptake after 10 minutes. The EXC resins exhibited excellent metal retention in preliminary column experiments, demonstrating a promising potential to separate americium and curium with a maximum decontamination factor of 88. Overall, this work successfully demonstrated the identification and conversion of synergic SX systems into novel synergic EXC resins for adjacent trivalent actinide separations.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"28 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375799","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}
Sarah E. Smith-Schmitz, Nicole C. Hurtig, Alexander P. Gysi
Raman spectroscopy provides a versatile tool for in situ characterization of aqueous rare earth elements (REE) speciation at the molecular level. Complexation of REE with ligands such as Cl− and OH− is of particular interest for understanding the mobility of REE in NaCl-bearing hydrothermal fluids responsible for enriching REE to economic levels in nature. Raman spectroscopic studies of REE speciation in Cl-bearing aqueous fluids are primarily conducted at ambient temperature, whereas natural systems indicate temperatures of >100–600 °C. In this study, the speciation of Dy in acidic chloride-bearing hydrothermal solutions was investigated using confocal Raman spectroscopy with a new capillary Raman heating stage at 20–300 °C. Background solutions (pure water, NaCl-solutions) and solutions with 0.14–1.8 mol kg−1 dissolved DyCl3 were sealed in quartz capillary cells. Comparison of the spectra for Dy chloride solutions with those for background solutions and the spectra for reference Dy-bearing solids was used to identify Raman bands specific to Dy–O and Dy–Cl bonds. The Raman band for the Dy–O stretching mode of hydrated Dy3+ aqua ions was measured at 365–384 cm−1 and a Raman band for the Dy–Cl stretching modes of Dy chloride complexes was measured near 240 cm−1. The Dy–O band decreases systematically with temperature, whereas the Dy–Cl band systematically increases, indicating a systematic increase in the stability of Dy chloride complexes with temperature. This study provides the framework for expanding the use of in situ Raman spectroscopy to investigate the speciation of REE in aqueous solutions to hydrothermal conditions.
{"title":"In situ Raman investigation of Dy complexation in Cl-bearing aqueous solutions at 20–300 °C","authors":"Sarah E. Smith-Schmitz, Nicole C. Hurtig, Alexander P. Gysi","doi":"10.1039/d4dt02170c","DOIUrl":"https://doi.org/10.1039/d4dt02170c","url":null,"abstract":"Raman spectroscopy provides a versatile tool for <em>in situ</em> characterization of aqueous rare earth elements (REE) speciation at the molecular level. Complexation of REE with ligands such as Cl<small><sup>−</sup></small> and OH<small><sup>−</sup></small> is of particular interest for understanding the mobility of REE in NaCl-bearing hydrothermal fluids responsible for enriching REE to economic levels in nature. Raman spectroscopic studies of REE speciation in Cl-bearing aqueous fluids are primarily conducted at ambient temperature, whereas natural systems indicate temperatures of >100–600 °C. In this study, the speciation of Dy in acidic chloride-bearing hydrothermal solutions was investigated using confocal Raman spectroscopy with a new capillary Raman heating stage at 20–300 °C. Background solutions (pure water, NaCl-solutions) and solutions with 0.14–1.8 mol kg<small><sup>−1</sup></small> dissolved DyCl<small><sub>3</sub></small> were sealed in quartz capillary cells. Comparison of the spectra for Dy chloride solutions with those for background solutions and the spectra for reference Dy-bearing solids was used to identify Raman bands specific to Dy–O and Dy–Cl bonds. The Raman band for the Dy–O stretching mode of hydrated Dy<small><sup>3+</sup></small> aqua ions was measured at 365–384 cm<small><sup>−1</sup></small> and a Raman band for the Dy–Cl stretching modes of Dy chloride complexes was measured near 240 cm<small><sup>−1</sup></small>. The Dy–O band decreases systematically with temperature, whereas the Dy–Cl band systematically increases, indicating a systematic increase in the stability of Dy chloride complexes with temperature. This study provides the framework for expanding the use of <em>in situ</em> Raman spectroscopy to investigate the speciation of REE in aqueous solutions to hydrothermal conditions.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"79 5 Pt 1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375802","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}
Richard Husar, Quentin Hervy, Thomas Dumas, Philippe Guilbaud, Matthieu Virot, Philippe Moisy
An original spectroelectrochemical approach was employed to probe in situ redox reactions with plutonium. Monitoring Pu electrolysis under aerated conditions revealed the formation of a transient species. Using chemometric methods, the associated spectroscopic signature was found to correspond with a dimeric peroxo-bridged Pu complex described 70 years ago, often referred to as the plutonium “brown” complex. A separate synthesis of this complex confirmed the presence of the transient species during electrolysis, challenging conventional concepts of Pu electrochemistry. The mechanistic role of the Pu “brown” complex during Pu electrolysis is also discussed.
{"title":"How plutonium “brown” peroxo complex emerges from electrolysis experiments","authors":"Richard Husar, Quentin Hervy, Thomas Dumas, Philippe Guilbaud, Matthieu Virot, Philippe Moisy","doi":"10.1039/d4dt02796e","DOIUrl":"https://doi.org/10.1039/d4dt02796e","url":null,"abstract":"An original spectroelectrochemical approach was employed to probe <em>in situ</em> redox reactions with plutonium. Monitoring Pu electrolysis under aerated conditions revealed the formation of a transient species. Using chemometric methods, the associated spectroscopic signature was found to correspond with a dimeric peroxo-bridged Pu complex described 70 years ago, often referred to as the plutonium “brown” complex. A separate synthesis of this complex confirmed the presence of the transient species during electrolysis, challenging conventional concepts of Pu electrochemistry. The mechanistic role of the Pu “brown” complex during Pu electrolysis is also discussed.","PeriodicalId":71,"journal":{"name":"Dalton Transactions","volume":"51 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375801","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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