- A series of organic-inorganic hybrid materials consisting of flexible organic amine modified polyoxomolybdates: synthesis, structures and properties
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A series of organic-inorganic hybrid complexes based on different types of polyoxomolybdates and transition metal complexes, namely, [Zn2(TPMA)2(H2P2Mo5O23)]·11H2O (1), [Zn2(TPMA)2(Mo8O26)] (2), [Co2(TPMA)2(Mo8O26)] (3), [Ni2(TPMA)2(Mo8O26)(H2O)2] (4), [Ni2(TPMA)2(2-PA)(H2O)](PMo12O40) (5) [Cu2(TPMA)2(Mo8O26)] (6), 2[Cu(TPMA)(CrMo6(OH)6O18)]·H[Cu2(TPMA)2(CrMo6(OH)6O18)]·4H2O (7) (TPMA = Tris[(2-pyridyl)methyl]amine, 2-PA = 2-picolinic acid), have been successfully synthesized under hydrothermal conditions. All complexes were characterized by single-crystal X-ray structural analysis, powder X-ray diffraction, IR spectroscopy and TG analysis. All the complexes showed polyoxomolybdate-based zero-dimensional (0D) structures, and could be further extended into three-dimensional (3D) supramolecular frameworks through hydrogen bonding interactions. In addition, the electrochemical properties of complexes 1-7 have been investigated. Interestingly, some complexes have efficient photocatalytic activities to degradate pararosaniline hydrochloride dye molecules.
- Gong, Chunhua,Zeng, Xianghua,Zhu, Chengfeng,Shu, Jiahui,Xiao, Pingxiu,Xu, Hao,Liu, Lichun,Zhang, Junyong,Zeng, Qingdao,Xie, Jingli
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p. 106248 - 106259
(2016)
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- Comparative Study of the Catalytic Oxidation of Catechols by Copper(II) Complexes of Tripodal Ligands
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Copper(II) complexes of the ligands tris(2-pyridylmethyl)amine (tpyma), tris(2-pyridylethyl)amine (tpyea), tris(3,5-dimethylpyrazol-1-ylmethyl)amine (tpzma) and tris(3,5-dimethylpyrazol-1-ylethyl)amine (tpzea) were prepared.The complexes, Cl or 2, were characterized by a combination of absorption and EPR spectroscopies and chemical analysis.The ability of the complexes to oxidize 3,5-di-tert-butylcatechol to 3,5-di-tert-butyl-o-benzoquinone has been studied and the results show that the rate of reaction is dependent on the nature of the heterocyclic donor, its basicity, steric considerations, the chelate ring size and the type of exogenous donor present.Large variations in the rate were observed with the most effective catalysts being those with pyridine donors which formed six-membered chelate rings; the complex 2 was the most active while 2 and Cl were inactive.Electrochemical data for the series of compounds show that there is a non-linear relationship between their ability to oxidize catechols and their reduction potentials.The most effective catalysts were those complexes which exhibited reduction potentials close to 0.00 V, while those that deviated from that potential by 200-300 mV in either direction were largely inactive.Within the range of complexes which were active, a steric match between the substrate and the complex also largely defined their reactivity.Comparisons to the biological system tyrosinase are drawn.
- Malachowski, Mitchell R.,Huynh, Hong B.,Tomlinson, Laura J.,Kelly, Richard S.,Furbee, James W.
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- Polypyridyl Co complex-based water reduction catalysts: why replace a pyridine group with isoquinoline rather than quinoline?
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The electronic effect of the substituent has been fully leveraged to improve the activity of molecular water reduction catalysts (WRCs). However, the steric effect of the substituents has received less attention. In this work, a steric hindrance effect was observed in a quinoline-involved polypyridyl Co complex-based water reduction catalyst (WRC), which impedes the formation of Co(iii)-H from Co(i), two pivotal intermediates for H2evolution, leading to significantly impaired electrocatalytic and photocatalytic activity with respect to its parent complex, [Co(TPA)Cl]Cl (TPA = tris(2-pyridinylmethyl)-amine). In sharp contrast, two isoquinoline-involved polypyridyl Co complexes exhibited significantly improved H2evolution efficiencies compared to [Co(TPA)Cl]Cl, benefitting mainly from the more basic and conjugated features of isoquinoline over pyridine. The dramatically different influences caused by the replacement of a pyridine group in the TPA ligand by quinoline and isoquinoline fully demonstrates the important roles of both the electronic and steric effects of a substituent. Our results may provide novel insights for designing more efficient WRCs.
- Guo, Xusheng,Li, Chao,Wang, Weibo,Hou, Yuanjun,Zhang, Baowen,Wang, Xuesong,Zhou, Qianxiong
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- Tuning the charge distribution and photoswitchable properties of cobalt-dioxolene complexes by using molecular techniques
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A series of cobalt complexes [Co(Mentpa)(diox)]PF 6·sol (diox = 3,5-di-tert-butyl-1,2-dioxolene; sol=ethanol, toluene; tpa = tris(2-pyridylmethyl)amine) were prepared by using tripod-like Mentpa (n = 0, 1, 2, 3), derived from tpa by successive introduction of methyl groups into the 6-position of the pyridine moieties, as an ancillary ligand. The steric hindrance induced by this substitution modulates the redox properties of the metal acceptor, thus determining the charge distribution of the metal-dioxolene moiety at room temperature. All of these complexes were characterised by using diffractometric studies, electronic spectroscopic analysis, and magnetic susceptibility measurements. In the solid state, the [Co(Mentpa)(diox)]+ ions (n = 0, 1) can be described as diamagnetic cobalt(III)-catecholato derivatives, whereas a cobalt(II)-semiquinonato description seems appropriate for the paramagnetic [Co(Me3tpa)(diox)]+ complex. The complex [Co(Me 2tpa)-(diox)]PF6·C2H5OH undergoes entropy-driven valence tautomeric interconversion at room temperature. Optically induced valence tautomerism was observed by irradiation of [Co(Mentpa)(diox)]PF6 complexes (n = 0, 1, 2) at cryogenic temperatures. The different relaxation kinetics of the photoinduced metastable phases are related to the respective free-energy changes of the interconversion, as estimated by cyclic voltammetric experiments at room temperature, and to the different lattice interactions, as supported by structural data. These results show the importance of molecular techniques for controlling the relaxation properties of photoinduced metastable species. At the same time, this behaviour strongly suggests that this paradigm exhibits intrinsic limits because of the less controllable factors that affect the process.
- Beni, Alessandra,Dei, Andrea,Laschi, Serena,Rizzitano, Mario,Sorace, Lorenzo
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- Tris(8-methoxy-2-quinolylmethyl)amine (8-MeOTQA) as a highly fluorescent Zn2+ probe prepared by convenient C3-symmetric tripodal amine synthesis
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A convenient synthesis of C3-symmetric tribenzylamine (TBA) derivatives has been investigated. The reaction of benzyl chlorides with acetaldehyde ammonia trimer (1) in the presence of base afforded tribenzylamines in high yields. This efficient method allows the diverse synthesis of TPA (tris(2-pyridylmethyl)amine) and TQA (tris(2-quinolylmethyl)amine) derivatives. Among the TQA compounds prepared, tris(8-methoxy-2-quinolylmethyl)amine (8-MeOTQA, 4) exhibited superior properties as a fluorescent zinc probe with high quantum yield (Zn = 0.51) and high sensitivity (limit of detection (LOD) = 3.4 nM). The X-ray crystallographic analysis of [Zn(8-MeOTQA)]2+ revealed that the steric and electronic effect of 8-methoxy substituents kicks out the solvent and counterion molecules from the metal coordination sphere, resulting in short Zn-Nquinoline coordination distances (2.04-2.07 ?). The pseudo hexacoordinate complex of 6-methoxy derivative, [Zn(6-MeOTQA)(DMF)(ClO4)]+, exhibited longer Zn-Nquinoline distances (2.07-2.19 ?) and much smaller fluorescence intensity (Zn = 0.027). The replacement of one of the three 8-methoxyquinolines with pyridine also afforded much less fluorescent zinc complex (Zn = 0.095) due to the solvent coordination (Zn-Nquinoline = 2.05-2.18 ? for [Zn(8-MeOBQPA)(CH3OH)]2+).
- Mikata, Yuji,Nodomi, Yuki,Ohnishi, Risa,Kizu, Asako,Konno, Hideo
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- Star-like oligo-arginyl-maltotriosyl derivatives as novel cell-penetrating enhancers for the intracellular delivery of colloidal therapeutic systems
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A novel nonpeptide, multiarmed oligo-arginyl derivative was engineered as a cell-penetration enhancer for the delivery of bioactive macromolecules and colloidal drug systems. Hepta-arginyl-maltotriosylamido-N-acetyl-dodecanoyl acid (Arg7-Malt-NAcC12 acid) was synthesized through a carefully designed multistep chemical protocol, as follows: (1) maltotriose derivatization with 12-amino-dodecanoic acid and acetylation of the free amino group; (2) esterification of the maltotriosyl hydroxyl groups with 2-bromo-isobutyryl bromide; and (3) synthesis of star-like oligomer bearing multiple copies of arginine moieties under atom transfer radical polymerization (ATRP) conditions. The intermediates and final product were characterized by 1H NMR, IR, mass spectrometry, colorimetric assays, and elemental analysis. Cytotoxicity studies on the final polymeric material showed that this novel cell-penetrating enhancer does not have significant toxic effects on MCF-7 and MC3T3-E1 cell lines. The IC50 was greater than 100 μM with both cell lines, while the polyethylenimine with similar average molecular mass (Mn) that was used as a reference showed an IC50 of 30 and 40 μM, for MCF-7 and MC3T3-E1, respectively. The biological properties of the novel bioconjugate were investigated using a fluorescein-labeled bovine serum albumin (FITC-BSA) as a hydrophilic cargo model. MCF-7 and MC3T3-E1 cells were incubated for 60 min with the Arg7-Malt-NAcC12- conjugated FITC-BSA [(Arg7-Malt-NAcC12) 2-FITC-BSA] or FITC-BSA, and the intracellular fluorescence level was analyzed by spectrofluorimetric analysis of cell lysate, cytofluorimetry, and confocal microscopy. The fluorescence of the lysate of MCF-7 and MC3T3-E1 cells that were incubated with (Arg7-Malt-NAcC12) 2-FITC-BSA at 37 °C was approximately 4.5 times higher than the fluorescence obtained with cells incubated with FITC-BSA. At 4 °C, the cell uptake of (Arg7-Malt-NAcC12)2-FITC-BSA was only 2 times higher than that of FITC-BSA. Cytofluorimetric studies showed that, after (Arg7-Malt-NAcC12)2-FITC-BSA treatment, over 80% of MCF-7 cells and over 95% of MC3T3-E1 cells displayed enhanced fluorescence. Confocal investigations showed punctuated fluorescence within the cytosol in both cell lines, indicating that (Arg7-Malt-NAcC 12)2-FITC-BSA was confined to endosomes, with no fluorescence observed in the nucleus.
- Bersani, Sara,Salmaso, Stefano,Mastrotto, Francesca,Ravazzolo, Elena,Semenzato, Alessandra,Caliceti, Paolo
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- Photocatalytic hydrogen evolution by Cu(II) complexes
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[Cu(TMPA)Cl]Cl (1) and [Cu(Cl-TMPA)Cl2] (2) exhibited efficient photocatalytic H2 evolution with a TON of 6108 and 10014 (6 h), respectively, in CH3CN/H2O solution (9:1, v/v) containing an Ir complex as the photosensitizer and triethylamine as the sacrificial reductant, representing the first example of photocatalytic Cu complex-based water reduction catalysts.
- Wang, Junfei,Li, Chao,Zhou, Qianxiong,Wang, Weibo,Hou, Yuanjun,Zhang, Baowen,Wang, Xuesong
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- Photo-induced water oxidation based on a mononuclear cobalt(II) complex
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Photo-induced water oxidation based on first row transition metal complexes has drawn much attention recently as a part of the efforts to design systems for solar fuel production. Here, the classic tetradentate ligand TPA (tris(2-pyridylmethyl)amine) is used together with cobalt(II) in CH 3CN to form a mononuclear cobalt complex [Co(TPA)Cl]Cl. Single crystal X-ray diffraction shows that [Co(TPA)Cl]Cl is composed of discrete cationic units with a penta-coordinate cobalt center, along with chloride counter ions. In borate buffer, the Co complex acts as a water oxidation catalyst, as shown by the presence of a catalytic wave in electrochemistry. Under visible light irradiation, in the presence of photosensitizer and electron acceptor, the Co complex catalyzes O2 evolution with a turnover frequency (TOF) of 1.0 mol(O2)·mol(Co) -1·s-1 and a turnover number (TON) of 55 mol(O 2)·mol(Co)-1 in pH 8 borate buffer. Copyright
- Wang, Hongyan,Lu, Yongbin,Mijangos, Edgar,Thapper, Anders
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- Fast Oxygen Reduction Catalyzed by a Copper(II) Tris(2-pyridylmethyl)amine Complex through a Stepwise Mechanism
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Catalytic pathways for the reduction of dioxygen can either lead to the formation of water or peroxide as the reaction product. We demonstrate that the electrocatalytic reduction of O2 by the pyridylalkylamine copper complex [Cu(tmpa)(L)]2+ in a neutral aqueous solution follows a stepwise 4 e?/4 H+ pathway, in which H2O2 is formed as a detectable intermediate and subsequently reduced to H2O in two separate catalytic reactions. These homogeneous catalytic reactions are shown to be first order in catalyst. Coordination of O2 to CuI was found to be the rate-determining step in the formation of the peroxide intermediate. Furthermore, electrochemical studies of the reaction kinetics revealed a high turnover frequency of 1.5×105 s?1, the highest reported for any molecular copper catalyst.
- Langerman, Michiel,Hetterscheid, Dennis G. H.
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- Quantitative Estimation of Ising-Type Magnetic Anisotropy in a Family of C3-Symmetric CoII Complexes
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In this paper, the influence of the structural and chemical effects on the Ising-type magnetic anisotropy of pentacoordinate CoII complexes has been investigated by using a combined experimental and theoretical approach. For this, a deliberate design and synthesis of four pentacoordinate CoII complexes [Co(tpa)Cl]?ClO4 (1), [Co(tpa)Br]?ClO4 (2), [Co(tbta)Cl]?(ClO4)?(MeCN)2?(H2O) (3) and [Co(tbta)Br]?ClO4 (4) by using the tripodal ligands tris(2-methylpyridyl)amine (tpa) and tris[(1-benzyl-1 H-1,2,3-triazole-4-yl)methyl]amine) (tbta) have been carried out. Detailed dc and ac measurements show the existence of field-induced slow magnetic relaxation behavior of CoII centers with Ising-type magnetic anisotropy. A quantitative estimation of the zero-field splitting (ZFS) parameters has been effectively achieved by using detailed ab initio theory calculations. Computational studies reveal that the wavefunction of all the studied complexes has a very strong multiconfigurational character that stabilizes the largest ms=±3/2 components of the quartet state and hence produce a large negative contribution to the ZFS parameters. The difference in the magnitudes of the Ising-type anisotropy can be explained through ligand field theory considerations, that is, D is larger and negative in the case of weak equatorial σ-donating and strong apical π-donating ligands. To elucidate the role of intermolecular interactions in the magnetic relaxation behavior between adjacent CoII centers, a diamagnetic isostructural ZnII analog (5) was synthesized and the magnetic dilution experiment was performed.
- Mondal, Amit Kumar,Jover, Jesús,Ruiz, Eliseo,Konar, Sanjit
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- Characterization of cobalt(III) hydroxamic acid complexes based on a tris(2-pyridylmethyl)amine scaffold: Reactivity toward cysteine methyl ester
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Six Co(III) complexes based on unsubstituted or substituted TPA ligands (where TPA is tris(2-pyridylmethyl)amine) and acetohydroxamic acid (A), N-methyl-acetohydroxamic acid (B), or N-hydroxy-pyridinone (C) were prepared and characterized by mass spectrometry, elemental analysis, and electrochemistry: [Co(III)(TPA)(A-2H)](Cl) (1a), [Co(III)((4-Cl2)TPA)(A-2H)](Cl) (2a), [Co(III)((6-Piva)TPA)(A-2H)](Cl) (3a), [Co(III)((4-Piva)TPA)(A-2H)](Cl) (4a) and [Co(III)(TPA)(B-H)](Cl)2 (1b), and [Co(III)(TPA)(C-H)](Cl) 2 (1c). Complexes 1a-c and 3a were analyzed by 1H NMR, using 2D (1H, 1H) COSY and 2D (1H, 13C) HMBC and HSQC, and shown to exist as a mixture of two geometric isomers based on whether the hydroxamic oxygen was trans to a pyridine nitrogen or to the tertiary amine nitrogen. Complex 3a exists as a single isomer that was crystallized. Its crystal structure revealed the presence of an H-bond between the pivaloylamide and the hydroximate oxygen. Complexes 1a, 2a, and 4a are irreversibly reduced beyond -900 mV versus SCE, while complexes 1b and 1c are reduced at less negative values of -330 and -190 mV, respectively. The H-bond in 3a increased the redox potential up to -720 mV. Reaction of complex 1a with l-cysteine methyl ester CysOMe was monitored by 1H NMR and UV-vis at 2 mM and 0.2 mM in an aqueous buffered solution at pH 7.5. Complex 1a was successively converted into an intermediate [Co(III)(TPA)(CysOMe-H)] 2+, 1d, by exchange of the hydroximate with the cysteinate ligand, and further into Co(III)(CysOMe-H)3, 5. An authentic sample of 1d was prepared and thoroughly characterized. A detailed 1H NMR analysis showed there was only one isomer, in which the thiolate was trans to the tertiary amine nitrogen.
- Alimi, Mickael,Allam, Anas,Galardon, Erwan,Artaud, Isabelle,Selkti, Mohamed,Tomas, Alain,Roussel, Pascal
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- Evaluating Metal-Ligand Interactions of Metal-Binding Isosteres Using Model Complexes
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Bioisosteres are a useful approach to address pharmacokinetic liabilities and improve drug-like properties. Specific to developing metalloenzyme inhibitors, metal-binding pharmacophores (MBPs) have been combined with bioisosteres, to produce metal-binding isosteres (MBIs) as alternative scaffolds for use in fragment-based drug discovery (FBDD). Picolinic acid MBIs have been reported and evaluated for their metal-binding ability, pharmacokinetic properties, and enzyme inhibitory activity. However, their structural, electronic, and spectroscopic properties with metal ions other than Zn(II) have not been reported, which might reveal similarities and differences between MBIs and the parent MBPs. To this end, [M(TPA)(MBI)]+ (M = Ni(II) and Co(II), TPA = tris(2-pyridylmethyl)amine) is presented as a bioinorganic model system for investigating picolinic acid, four heterocyclic MBIs, and 2,2′-bipyridine. These complexes were characterized by X-ray crystallography as well as NMR, IR, and UV-vis spectroscopies, and their magnetic moments were accessed. In addition, [(TpPh,Me)Co(MBI)] (TpPh,Me = hydrotris(3,5-phenylmethylpyrazolyl)borate) was used as a second model compound, and the limitations and attributes of the two model systems are discussed. These results demonstrate that bioinorganic model complexes are versatile tools for metalloenzyme inhibitor design and can provide insights into the broader use of MBIs.
- Cohen, Seth M.,Dick, Benjamin L.,Kalaj, Mark,Karges, Johannes,Prosser, Kathleen E.,Seo, Hyeonglim
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p. 17161 - 17172
(2021/11/17)
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- Bioinspired manganese complex for room-temperature oxidation of primary amines to imines by t-butyl hydroperoxide
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A sustainable method is developed for the selective and additive-free synthesis of imines from primary amines with TBHP catalyzed by bioinspired manganese complex (MnCl2(TPA)) at room temperature. Use of 0.2 mol % MnCl2(TPA) was efficient enough for this transformation by offering excellent conversions up to 98.2% along with 93.4% product yield within 1 h. The influence of reaction parameters (catalyst dosage, solvent, reaction temperature, time, etc.) on the catalytic performance was also investigated in detail. Building on these results, the selected MnCl2(TPA) was further employed to transform various primary amines into corresponding imines and exhibited good compatibility even for the challenging aliphatic amine. The high efficiency, combining with a large substrate scope and ambient reaction conditions, makes the developed bioinspired Mn complex/TBHP system a promising pathway to produce imines. This work also paves a way to the expansion of non-heme metal catalysts as efficient platforms for various oxidation reactions.
- Lei, Lin,Chen, Yaju,Feng, Zhenfeng,Deng, Chunyan,Xiao, Yepeng
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- Understanding the Origin of One- or Two-Step Valence Tautomeric Transitions in Bis(dioxolene)-Bridged Dinuclear Cobalt Complexes
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Valence tautomerism (VT) involves a reversible stimulated intramolecular electron transfer between a redox-active ligand and redox-active metal. Bis(dioxolene)-bridged dinuclear cobalt compounds provide an avenue toward controlled two-step VT interconversions of the form {CoIII-cat-cat-CoIII} ? {CoIII-cat-SQ-CoII}?{CoII-SQ-SQ-CoII} (cat2- = catecholate, SQ·- = semiquinonate). Design flexibility for dinuclear VT complexes confers an advantage over two-step spin crossover complexes for future applications in devices or materials. The four dinuclear cobalt complexes in this study are bridged by deprotonated 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-5,5′,6,6′-tetraol (spiroH4) or 3,3,3′,3′-tetramethyl-1,1′-spirobi(indan)-4,4′,7,7′-tetrabromo-5,5′,6,6′-tetraol (Br4spiroH4) with Mentpa ancillary ligands (tpa = tris(2-pyridylmethyl)amine, n = 0-3 corresponds to methylation of the 6-position of the pyridine rings). Complementary structural, magnetic, spectroscopic, and density functional theory (DFT) computational studies reveal different electronic structures and VT behavior for the four cobalt complexes; one-step one-electron partial VT, two-step VT, incomplete VT, and temperature-invariant {CoIII-cat-cat-CoIII} states are observed. Electrochemistry, DFT calculations, and the study of a mixed-valence {ZnII-cat-SQ-ZnII} analog have allowed elucidation of thermodynamic parameters governing the one- and two-step VT behavior. The VT transition profile is rationalized by (1) the degree of electronic communication within the bis(dioxolene) ligand and (2) the matching of cobalt and dioxolene redox potentials. This work establishes a clear path to the next generation of two-step VT complexes through incorporation of mixed-valence class II and class II-III bis(dioxolene) bridging ligands with sufficiently weak intramolecular coupling.
- Boskovic, Colette,Gable, Robert W.,Gransbury, Gemma K.,Hay, Moya A.,Janetzki, Jett T.,Livesay, Brooke N.,Shores, Matthew P.,Starikova, Alyona
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supporting information
p. 10692 - 10704
(2020/07/04)
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- CO2-Controlled Reductive Amination Reactions with NaBH4
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We report the use of CO2 to curb the reactivity of NaBH4 enabling its use in reductive amination reactions. CO2 readily reacts with NaBH4 to decrease its capacity to reduce aldehydes to alcohols while remaining able to reduce imines and iminium ions for desired alkylation reactions. The formation of NaBH(OCHO)3 as a reducing reagent was critical to achieve the desired selectivity. A general protocol was established for C–N bond formation reactions and replacing NaBH4 with NaBD4 allowed for reductive amination with concomitant deuteration to be carried out.
- Petersen, Allan R.,Lauridsen, Jerik Mathew Valera,Lee, Ji-Woong
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supporting information
p. 7368 - 7372
(2020/11/30)
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- Evaluation of cobalt complexes with tripod ligands for zinc finger targeting
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Cobalt complexes have been demonstrated to target zinc fingers, as shown by investigations of Doxovir, the trade name of the [CoIII(acacen)(2-Me-Imz)2]+ drug in clinical trials. Mechanistic studies indicate zinc finger disruption by metal coordination to His residues. Other than Doxovir, a few studies have investigated other ligands and geometries for cobalt complexes for zinc finger targeting. Tripod ligands demonstrated good zinc and cobalt chelation. In this manuscript, we report the ability of CoII and CoIII complexes of tri(2-pyridylmethyl)amine and N,N-di(2-pyridylmethyl)glycinate to disrupt zinc fingers. The results obtained by mass spectrometry and X-ray absorption spectroscopy demonstrate that the complexes were able to remove zinc from the zinc fingers. The product was oxidised apo-peptide. In contrast, the ligands themselves were able to remove zinc, and they did not promote oxidation, resulting in free Cys residues. Cobalt finger adducts were not detected for the complexes with tripod ligands unless they were coordinated to planar ligands such as salen or acacen. Studies of the interactions of cobalt complexes with amino acids demonstrated that tripod ligands promote the cysteine reaction, while the salen ligands promote histidine coordination, demonstrating a different mechanism of action. The results reported here are significant for better understanding and further design of zinc finger targeting compounds.
- Aealsteinsson, Heiear Mar,Abbehausen, Camilla,Galuppo, Carolina,Lima, Frederico A.
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p. 16143 - 16153
(2020/12/03)
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- N, N - dialkyl pyrrolidine pressure concentrated water ion liquid preparation method and its application (by machine translation)
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The invention relates to a N, N - dialkyl pyrrolidine pressure concentrated water ion liquid preparation method and its application, the method to N - alkyl pyrrolidine and alkyl alcohol as raw material through the electrolysis mode, in the electrolytic cell is provided with a cation exchange membrane, cation exchange membrane into the cathode with the anode compartment of the electrolytic aluminum, electrolytic taken out after completion of the cathode electrolyte, separation and purification, to obtain N, N - dialkyl pyrrolidines pressure concentrated water ionic liquid, the preparation method is simple, mild condition, purity and high yield. The N, N - dialkyl pyrrolidine pressure concentrated water ionic liquid as solvent, in order to chlorine methyl pyridine hydrochloride and ammonia as raw material, synthetic three-pyridine methyl amine compound, the preparation of yield and high purity, without follow-up separation, low cost, environmental protection, the ionic liquid can be used repeatedly, is suitable for industrial production. (by machine translation)
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Paragraph 0048-0053
(2019/10/29)
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- Syntheses, structure and properties of dinuclear Co complexes with bis(catecholate) ligands – Effect of a quinoline ring in the terminal group
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Two types of biscatechol, namely H4L1 (5,5′-(buta-1,3-diyne-1,4-diyl)bis(3-t-butylcatechol)) and H4L2 (5,5′-(ethyne-1,2-diyl)bis(3-t-butylcatechol)) were synthesized. In these ligands, two redox active catechol moieties are connected by one or two triple bonds. Also, tpa (tris(2-pyridylmethyl) amine), bpqa (bis(2-pyridylmethyl)(2-quinolylmethyl)amine) and pbqa ((2-pyridylmethyl)bis(2-quinolylmethyl)amine) were synthesized as terminal ligands of the tetracoordinated tripod type. In total, six dinuclear Co complexes were synthesized from these biscatechol and terminal ligands as follows: [Co2(L1)(tpa)2](BF4)2 (1), [Co2(L1)(bpqa)2](PF6)2 (2), [Co2(L1)(pbqa)2](PF6)2 (3), [Co2(L2)(tpa)2](BF4)2 (4), [Co2(L2)(bpqa)2](PF6)2 (5), [Co2(L2)(pbqa)2](PF6)2 (6). Of the six dinuclear Co complexes, complex 6, which was isolated as a mixed valent state CoII(HS)-[SQ-Cat]-CoIII(LS) compound, showed an absorption intensity at around 703 nm (MLCT bands) that increased with increasing temperature in acetonitrile solution. In addition, an investigation of the magnetic properties of the complex 6 with SQUID showed that the χMT value gradually increased as the temperature increased from 150 to 380 K. This suggests that a transition from CoIII(LS) (S = 0) to CoII(HS) (S = 3/2) accompanies the temperature rise. This means the steric hindrance and electronic effect of the quinolyl groups around the Co ion produce a coordination atmosphere weaker than that of pyridyl groups, with the result that the CoIII ions easily convert to CoII ions.
- Suenaga, Yusaku,Mibu, Takuto,Okubo, Takashi,Maekawa, Masahiko,Kuroda-Sowa, Takayoshi
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supporting information
p. 480 - 485
(2019/08/26)
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- Polyacid-based metal organic hybrid material as well as preparation method and application thereof
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The invention discloses a polyacid-based metal organic hybrid material as well as a preparation method and application thereof. The polyacid-based metal organic hybrid material is synthesized from metal salt, ammonium molybdate and an organic ligand according to an evaporative reflux method and/or a hydrothermal synthesis method; or the polyacid-based metal organic hybrid material is synthesized from ammonium molybdate and the organic ligand according to the evaporative reflux method, wherein the metal salt is copper salt or cobalt salt, and the organic ligand is tripyridine methylene amine and/or 1-(tetrazole-5-yl)-3-(triazole-1-yl)benzene; tripyridine methylene amine is abbreviated as TPMA, and 1-(tetrazole-5-yl)-3-(triazole-1-yl) benzene is abbreviated as 1,3-ttb. The polyacid-based metal organic hybrid material disclosed by the invention has the function of a photocatalytic material for degradation of organic dyes.
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Paragraph 0045
(2019/01/08)
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- METHOD OF PRODUCING PHENOLIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of efficiently producing a phenolic compound by direct oxidation of an aromatic compound. SOLUTION: The present invention provides a method of producing a phenolic compound by oxidizing an aromatic compound by an oxidizer in the presence of a copper complex having as a ligand a compound represented by the formula (I) or (II) in the figure. (In the formulas, R1 to R9 each independently represent a methylene group or ethylene group.) SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0037
(2018/03/30)
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- Catalytic electrophilic halogenations and haloalkoxylations by non-heme iron halides
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Synthetic non-heme iron halides promote sub-stoichiometric aliphatic halogenation reactions via a radical mechanism. Complementary to such activity, we have developed an electrophilic halogenation of arenes employing non-heme iron halides. A catalytic version of these reactions has also been developed using potassium halide as the source of halogen atom for arenes at room temperature. Efforts towards understanding the mechanism of these catalytic halogenation reactions led to the discovery of the haloalkoxylation of olefins by a non-heme iron complex. Implications of these findings with respect to natural transformations are also discussed.
- Rana, Sujoy,Bag, Sukdev,Patra, Tuhin,Maiti, Debabrata
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supporting information
p. 2453 - 2458
(2014/09/30)
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- An efficient oxygen evolving catalyst based on a μ-O diiron coordination complex
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A family of oxygen evolving catalysts was investigated, which was based on the most desired first-row transition metal iron. Among them, the highest turnover number of 2380 was obtained in acetate buffer at pH 4.5 with [(TPA)2Fe2(μ-O)(μ-OAc)]3+. This journal is
- Liu, Yongdong,Xiang, Rui,Du, Xiaoqiang,Ding, Yong,Ma, Baochun
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p. 12779 - 12782
(2015/05/20)
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- Iron(II) α-aminopyridine complexes and their catalytic activity in oxidation reactions: A comparative study of activity and ligand decomposition
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New well-defined FeII complexes bearing bi- and tridentate α-aminopyridine ligands were synthesized, and their catalytic activity in the oxidation of hydrocarbons and alcohols utilizing peroxide oxidants was investigated. The tridendate bis-(picolyl)amine ligand 6 and its benzylated analogue 7 were converted into complexes [FeII(6)2] OTf2 (96 %, X-ray; OTf= CF3SO3 -) and [FeII(7)2]OTf2 (90 %). The bidentate aminopyridine ligand 8 was converted into [FeII(8) 2(OTf)2] (93 %, X-ray). The new complexes are catalytically active in the oxidation of secondary alcohols and benzylic methylene groups to the corresponding ketones, of toluene to benzaldehyde, and of cyclohexene to cyclohexene oxide (3 mol% catalyst, tBuOOH (4 equiv), RT, 2-6 h, 28 to 85% yield of isolated product). The catalytic oxidation of cyclohexane with ROOH (R=H, tBu) to an alcohol/ketone mixture with low ratio revealed that these oxidations follow largely a radical mechanism, except when [Fe II(6)2]OTf2 was employed and H 2O2 was added slowly. Together with known bi- and tetradendate iron complexes, a comparative study showed slight reactivity differences for the newly prepared complexes, with the highest observed for [FeII(6)2]OTf2 and [FeII(7) 2]OTf2. The reaction of the new complexes with peroxides was followed over time by UV/Visible spectroscopy; this revealed a fast reaction between the two reactants within minutes. Ligand-decomposition pathways were investigated, and revealed that the NCH2 units of the complexes are rapidly oxidized to the corresponding amides NC=O. The iron complex [Fe II(6)2]OTf2 showed no decrease in catalytic activity and a moderate decrease in selectivity when first subjected to oxidative conditions similar to those employed in catalysis. Thus, oxidative ligand deterioration had a marginal effect on the catalytic activity of the iron complex [FeII(6)2]OTf2.
- Lenze, Matthew,Martin, Erin T.,Rath, Nigam P.,Bauer, Eike B.
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p. 101 - 116
(2013/05/22)
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- COPPER-OXYGEN ADDUCT COMPLEXES
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The invention at hand describes Cu-(II)-oxygen adduct complexes, which are stable at room temperature, as well as methods for their production. In this, compounds of the general formula [L-Cu—O—O—Cu-L](BAr4)2 are concerned. Here, BAr4? is a tetraarylborate anion, selected from tetraphenylborate and tetrakis(3,5-trifluoromethyl)phenylborate. L represents a tripodal tetradentate ligand, wherein, each of the four binding sites of the tripodal tetradentate ligand is a nitrogen atom. Each of the three podal ligands is suitable for comprising an aliphatic amine or a nitrogen-containing heteroaromatic compound independently of one another. A bridge of one to four carbon atoms is located between the central nitrogen atom and the nitrogen atom of each of the podal ligands. The Cu-(II)-oxygen adduct complexes according to the present invention are produced, by initially reacting the ligand L with a Cu-(I) salt to [Cu-L]X. Subsequently, the anion X of the Cu-(I) complex [Cu-L]X is replaced with tetraarylborate and the compound [Cu-L]BAr4 obtained in this way is finally exposed to an oxygen-containing atmosphere. Hereby, [L-Cu—O—O—Cu-L](BAr4)2 is formed. The Cu-(II)-oxygen adduct complexes are suitable for being used as oxidation catalysts, for example for the oxidation of benzene to phenol or methane to methanol, for the oxidation of hydrogen, aromatic and aliphatic, saturated and unsaturated hydrocarbons, as well as alcohols and amines. Furthermore, detection of the Cu-(II)-oxygen adduct complexes according to the present invention is suitable for being used for the detection of oxygen.
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Page/Page column 8
(2012/02/01)
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- CORONA-LIKE (GUANIDYL)-OLIGOSACCHARIDIC DERIVATIVES AS CELL-PENETRATING ENHANCERS FOR INTRACELLULAR DELIVERY OF COLLOIDAL THERAPEUTIC SYSTEMS
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A novel class of cell-penetrating enhancers with unusual chemical structure is herein disclosed. Said cell-penetrating enhancers are non-linear and non peptidic (guanidyl)-oligosaccharidic derivatives, which can be easily obtained according to simple and reproducible synthetic steps. A wide array of cell penetration enhancers can be obtained by slight modification of the main structure oligosaccharidic backbone and in order to provide for their conjugation or physical combination with a variety of therapeutic systems. These molecules can be designed for conjugation to proteins or polymer therapeutics or for surface decoration of liposomes or nanoparticles. Finally, the cationic features and the penetration enhancer properties of the corona-like (guanidyl)-oligosaccharidic derivatives can be exploited for oligonucleotide, namely siRNA, or gene delivery.
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Page/Page column 14-15
(2012/08/07)
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- TECHNETIUM- AND RHENIUM-BIS(HETEROARYL) COMPLEXES, AND METHODS OF USE THEREOF
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One aspect of the invention relates to complexes of a radionuclide with various heteroaryl ligands, e.g., imidazolyl and pyridyl ligands, and their use in radiopharmaceuticals for a variety of clinical diagnostic and therapeutic applications. Another aspect of the invention relates to imidazolyl and pyridyl ligands that form a portion of the aforementioned complexes. Methods for the preparation of the radionuclide complexes are also described. Another aspect of the invention relates to imidazolyl and pyridyl ligands based on derivatized lysine, alanine and bis-amino acids for conjugation to small peptides by solid phase synthetic methods. Additionally, the invention relates to methods for imaging regions of a mammal using the complexes of the invention.
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Page/Page column 79
(2008/06/13)
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- Technetium-depyridine complexes, and methods of use thereof
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One aspect of the invention relates to novel complexes of technetium (Tc) with various heteroaromatic ligands, e.g., pyridyl and imidazolyl ligands, and their use in radiopharmaceuticals for a variety of clinical diagnostic and therapeutic applications. Another aspect of the invention relates to novel pyridyl ligands that form a portion of the aforementioned complexes. Methods for the preparation of the technetium complexes are also described. Another aspect of the invention relates to novel pyridyl ligands based on derivatized lysine, alanine and bis-amino acids for conjugation to small peptides by solid phase synthetic methods. Additionally, the invention relates to methods for imaging regions of a mammal using the complexes of the invention.
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- Control of Intramolecular Magnetic Interaction by the Spin Polarization of d? Spin to p? Orbital of an Organic Bridging Ligand
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Multinuclear metal complexes have been designed with ferromagnetic interactions between the metal centers by considering the topological network of d? spin to the bridging ligand.The four complexes (ClO4)3*4H2O (1), (2), (NO3)4*3H2O (3), and (4), with tpa = tris(2-pyridylmethyl)amine, H3ta = trimesic acid, bpepm = 4,6-bispyrimidine, and H2bpmar = 4,6-bis-2-methylresorcinol, have been synthesized, and crystal structures of 1 and 2 have been determined.Magnetic properties have been investigated in the 2-270 K temperature range.Central metal ions in each complex are cupric for 1 and 4, high-spin ferrous for 2, and high-spin ferric species for 3, respectively.Magnetic susceptibility measurements for 1, 2, and 4 showed antiferromagnetic behavior, and the Weiss constants for the data above 100 K are -3.26, -3.86, and -2.09 K, respectively.Magnetic data for 3 have been quantitatively studied above 10 K and have revealed that 3 exhibits ferromagnetic coupling with a magnetic exchange coupling constant of J = + 0.65(3) cm-1 (where H = -2JS1S2).The measurement of magnetization (M) versus the field (H) for 3 has shown that the quantum number of the total angular momentum (J) at 4.0 and 8.5 K is larger than J = 4, where the expected value (J) in absence of ferromagnetic interaction is 5/2.The ferromagnetic interaction in 3 was interpreted by the spin polarization of d? spin to the ligand p? orbital.Crystal data: (ClO4)3*4H2O (1), monoclinic, space group C2/c, a = 36.228(8) Angstroem, b = 19.565(3) Angstroem, c = 26.341(6) Angstroem, β = 122.07(1) deg, V = 15821(6) Angstroem3, Z = 8, R = 0.090 (Rw = 0.096) for 4992 data points with /F0/ > 3?(F0); (2), monoclinic, space group C2/c, a = 42.28(1) Angstroem, b = 13.467(4) Angstroem, c = 15.527(3) Angstroem, β = 94.83(2) deg, V = 8810(4) Angstroem3, Z = 8, R = 0.050 (Rw = 0.048) for 2676 data points with /F0/ > 3?(F0).
- Oshio, Hiroki,Ichida, Hikaru
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p. 3294 - 3302
(2007/10/02)
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- Reversible reaction of O2 (and CO) with a copper(I) complex. X-ray structures of relevant mononuclear Cu(I) precursor adducts and the trans-(μ-1,2-peroxo)dicopper(II) product
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The study of copper-dioxygen interactions and reactivity is of interest in chemical systems which involve redox activity or oxidative transformations and in biological systems where copper proteins are known to effect a variety of functions including dioxygen transport, substrate oxygenation, and O2 reduction. Here, we describe reactions of O2 (and CO) with a mononuclear copper(I) complex containing a tripodal tetradentate ligand L (tris(2-pyridylmethyl)amine). Cationic copper(I) complexes [LCu(D)]+ (D = RCN (1a-c), CO (1d, νCO = 2075 cm-1), or PPh3 (1e)) can be isolated as stable compounds, and the X-ray structures of [LCu(PPh3)]+ (1e) and [L′Cu(CH3CN)]+ (1′, L′ = bis(2-pyridylmethyl)-(5-carbomethoxy-2-pyridylmethyl)amine) are reported. Compound 1e exhibits a pseudotetrahedral tetracoordination with ligation from two pyridines plus alkylamine and phosphine donors; the third pyridine donor is uncoordinated. Complex 1′ possesses a distorted pentacoordinate structure, resembling more closely that found for typical Cu(II) complexes with L, i.e., with a trigonal bipyramidal geometry. [LCu(MeCN)]+ (1a) reacts to give the dioxygen complex [(LCu)2(O2)]2+ (2) which is stable at -80°C in EtCN or CH2Cl2 solution [λmax = 525 nm (∈ = 11 500 M-1 cm-1)]. The binding of O2 and CO to 1a is reversible, and UV-vis spectroscopy is used to demonstrate cycling between 1a and 2 (vacuum cycling). Thermally unstable solids [(LCu)2(O2)]2+ (2) were isolated as PF6- or ClO4- salts, and crystals suitable for X-ray diffraction were obtained. [(LCu)2(O2)]2+ (2) stands as the first copper-dioxygen complex to be structurally characterized, and full details are reported and compared to structurally related peroxodicobalt(III) complexes also possessing a trans-(μ-1,2-peroxo) coordination. Notable features include Cu?Cu = 4.359(1) A?, and the O-O bond length is 1.432(6) A?, a typical peroxide bond distance. [(LCu)2(O2)]2+ (2) exhibits very normal looking 1H and 13C NMR spectra, indicative of strong magnetic coupling between Cu(II) ions. This and other properties are compared to those of oxyhemocyanin (O2 carrier) and other Cu2O2 complexes.
- Tyeklár, Zoltán,Jacobson, Richard R.,Wei, Ning,Murthy, Narasappa Narasimha,Zubieta, Jon,Karlin, Kenneth D.
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p. 2677 - 2689
(2007/10/02)
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