- Py-Macrodipa: A Janus Chelator Capable of Binding Medicinally Relevant Rare-Earth Radiometals of Disparate Sizes
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Nuclear medicine leverages different types of radiometals for disease diagnosis and treatment, but these applications usually require them to be stably chelated. Given the often-disparate chemical properties of these radionuclides, it is challenging to find a single chelator that binds all of them effectively. Toward addressing this problem, we recently reported a macrocyclic chelator macrodipa with an unprecedented "dual-size-selectivity"pattern for lanthanide (Ln3+) ions, characterized by its high affinity for both the large and the small Ln3+ (J. Am. Chem. Soc, 2020, 142, 13500). Here, we describe a second-generation "macrodipa-type"ligand, py-macrodipa. Its coordination chemistry with Ln3+ was thoroughly investigated experimentally and computationally. These studies reveal that the Ln3+-py-macrodipa complexes exhibit enhanced thermodynamic and kinetic stabilities compared to Ln3+-macrodipa, while retaining the unusual dual-size selectivity. Nuclear medicine applications of py-macrodipa for chelating radiometals with disparate chemical properties were assessed using the therapeutic 135La3+ and diagnostic 44Sc3+ radiometals representing the two size extremes within the rare-earth series. Radiolabeling and stability studies demonstrate that the rapidly formed complexes of these radionuclides with py-macrodipa are highly stable in human serum. Thus, in contrast to gold standard chelators like DOTA and macropa, py-macrodipa can be harnessed for the simultaneous, efficient binding of radiometals with disparate ionic radii like La3+ and Sc3+, signifying a substantial achievement in nuclear medicine. This concept could enable the facile incorporation of a breadth of medicinally relevant radiometals into chemically identical radiopharmaceutical agents. The fundamental coordination chemistry learned from py-macrodipa provides valuable insight for future chelator development.
- Hu, Aohan,Aluicio-Sarduy, Eduardo,Brown, Victoria,Macmillan, Samantha N.,Becker, Kaelyn V.,Barnhart, Todd E.,Radchenko, Valery,Ramogida, Caterina F.,Engle, Jonathan W.,Wilson, Justin J.
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- Photocatalytic CO2 Reduction by Trigonal-Bipyramidal Cobalt(II) Polypyridyl Complexes: The Nature of Cobalt(I) and Cobalt(0) Complexes upon Their Reactions with CO2, CO, or Proton
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The cobalt complexes CoIIL1(PF6)2 (1; L1 = 2,6-bis[2-(2,2′-bipyridin-6′-yl)ethyl]pyridine) and CoIIL2(PF6)2 (2; L2 = 2,6-bis[2-(4-methoxy-2,2′-bipyridin-6′-yl)ethyl]pyridine) were synthesized and used for photocatalytic CO2 reduction in acetonitrile. X-ray structures of complexes 1 and 2 reveal distorted trigonal-bipyramidal geometries with all nitrogen atoms of the ligand coordinated to the Co(II) center, in contrast to the common six-coordinate cobalt complexes with pentadentate polypyridine ligands, where a monodentate solvent completes the coordination sphere. Under electrochemical conditions, the catalytic current for CO2 reduction was observed near the Co(I/0) redox couple for both complexes 1 and 2 at E1/2 = -1.77 and -1.85 V versus Ag/AgNO3 (or -1.86 and -1.94 V vs Fc+/0), respectively. Under photochemical conditions with 2 as the catalyst, [Ru(bpy)3]2+ as a photosensitizer, tri-p-tolylamine (TTA) as a reversible quencher, and triethylamine (TEA) as a sacrificial electron donor, CO and H2 were produced under visible-light irradiation, despite the endergonic reduction of Co(I) to Co(0) by the photogenerated [Ru(bpy)3]+. However, bulk electrolysis in a wet CH3CN solution resulted in the generation of formate as the major product, indicating the facile production of Co(0) and [Co-H]n+ (n = 1 and 0) under electrochemical conditions. The one-electron-reduced complex 2 reacts with CO to produce [Co0L2(CO)] with νCO = 1894 cm-1 together with [CoIIL2]2+ through a disproportionation reaction in acetonitrile, based on the spectroscopic and electrochemical data. Electrochemistry and time-resolved UV-vis spectroscopy indicate a slow CO binding rate with the [CoIL2]+ species, consistent with density functional theory calculations with CoL1 complexes, which predict a large structural change from trigonal-bipyramidal to distorted tetragonal geometry. The reduction of CO2 is much slower than the photochemical formation of [Ru(bpy)3]+ because of the large structural changes, spin flipping in the cobalt catalytic intermediates, and an uphill reaction for the reduction to Co(0) by the photoproduced [Ru(bpy)3]+.
- Shimoda, Tomoe,Morishima, Takeshi,Kodama, Koichi,Hirose, Takuji,Polyansky, Dmitry E.,Manbeck, Gerald F.,Muckerman, James T.,Fujita, Etsuko
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- Synthesis, characterization, and mechanism studies of bis(imino)pyridine ligands and their Cr(III) compounds
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Two new bis(imino)pyridine ligands L1, L2 (L1 = 2,6-bis[1-(4-bromophenylimino)]pyridine, L2 = 2,6-bis[1-(4-methylphenylimino)]pyridine) have been prepared. Their compounds [CrCl3L1] (I) and [Cr(Cl)(μ-Cl)(L2′)]2 (II) (L2′ = 6-bis(6-methylquinoline)pyridine) for olefin oligomerization were obtained by hydrothermal methods, during which L2′ was appeared from L2, and characterized by elemental analysis, single-crystal X-ray analysis (CIF files CCDC nos. 1025448 (I),1025447 (II)), IR spectra and melting point test. Compound I is a mononuclear compound, while compound II, bridged with the chlorine atoms, is a binuclear compound. The transformation mechanism between L2 and L2′ is also studied, and the possible reason is due to the presence of the electron-donating groups as substituents on L2. The subsequent studies on that will be carried on.
- Li, S. W.,Wang, Y. F.,Li, X. P.,Zhao, J. S.,Wang, J. L.
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- Synthesis of pyridine acrylates and acrylamides and their corresponding pyridinium ions as versatile cross-linkers for tunable hydrogels
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A small library of cross-linkers for hydrogels was synthesized. The cross-linkers consisted of 2,6- and 3,5-diacylpyridine or 2,4,6-triacylpyridine as the core unit, which were tethered via ethylene glycol, amino ethanol, and 1,n-diamine spacers to terminal acrylate or acrylamide moieties. Esterification and amide formation of the terminal acryl units were found to be dependent on the ratio of NH/O in the spacer, the constitution pattern of the pyridine ring, and the total number of acryl groups. Thus, esters generally gave higher yields than amides decreasing with increasing number of NH in the spacer and with increasing number of acryl units. In the case of 3,5-diacylpyridine derivatives, these trends were less prominent as compared to the 2,6-diacylpyridine series, indicating that steric hindrance and unfavorable hydrogen bonding interaction of the spacers might influence the observed reactivity differences. The 3,5-diacylpyridines were converted to the N-methylpyridinium salts and selected members of both neutral and cationic 3,5-diacylpyridinium derivatives were submitted to hydrogelations with synthetic polymer poly(1-glycidylpiperazine) via aza-Michael addition and thiolated natural hyaluronan via thio-Michael reaction, respectively. Rheological properties of the resulting hydrogels were studied, revealing that both spacer type as well as charge affected elastic moduli and degree of swelling. Georg Thieme Verlag Stuttgart New York.
- Mateescu, Markus,Nuss, Isabell,Southan, Alexander,Messenger, Hayley,Wegner, Seraphine V.,Kupka, Julia,Bach, Monika,Tovar, Guenter E. M.,Boehm, Heike,Laschat, Sabine
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- Synthesis and application of PNP pincer ligands in rhodium-catalyzed hydroformylation of cycloolefins
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Two new phosphorus ligands (L1 and L2) were developed for rhodium-catalyzed hydroformylation of cycloolefins. L1 produced high conversion for cyclohexene (94.7%) and high dialdehyde selectivity for NBD (97.1%) and DCPD (98.4%). Analogue pincer ligands L3-L6 with different steric and electronic character were also investigated in these hydroformylations.
- Wu, Qianhui,Zhou, Fanding,Shu, Xiao,Jian, Lei,Xu, Bin,Zheng, Xueli,Yuan, Maolin,Fu, Haiyan,Li, Ruixiang,Chen, Hua
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p. 107305 - 107309
(2016)
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- Synthesis and fluorescence properties of lanthanide(III) complexes of a novel bis(pyrazolyl-carboxyl)pyridine-based ligand
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A novel bis-pyrazolyl-carboxyl ligand, 2,6-bis(5-methyl-3-carboxypyrazol-1-ylmethyl)pyridine (L), was designed and synthesized and its several lanthanide(III) complexes Eu(III), Tb(III), Sm(III) and Gd(III) were successfully prepared and characterized in detail based on elemental analysis, infrared, mass, proton nuclear magnetic resonance spectroscopy and TG-DTA studies. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring and pyrazole rings. The fluorescence spectra exhibits that the Tb(III) complex and the Eu(III) complex display characteristic metal-centered fluorescence in solid state while ligand fluorescence is completely quenched. However, the Tb(III) complex displays more effective fluorescence than the other complexes, which is attributed to especial effectivity in transferring energy from the lowest triplet energy level of the ligand (L) onto the excited state (5D4) of Tb(III).
- Shi, Xiao-Ming,Tang, Rui-Ren,Gu, Guo-Liang,Huang, Ke-long
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- The synthesis and property of dihydropyrene derivatives containing a nitrogen atom
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Dihydropyrene (DHP) is 14π aromatic compound and applied as an aromatic probe by chemical shift of internal methyl groups in 1H-NMR spectra. DHP containing a nitrogen atom 1a and 2a were designed as photochromic compounds which were restrained thermal-isomerization. 1a and 2a were confirmed as DHP types by 1H-NMR spectra. Chemical shifts of internal methyl groups of 1a and 2a were observed at the lower magnetic field than that of DHP 3a. According to optimized structures of 1a and 3a, it was expected that the internal methyl group located of the out at center of 14π annulene ring. Isomerization to [2.2]metacyclophanediene 1b from DHP 1a by photo-irradiation of visible light was not observed.
- Chifuku, Kazufumi,Sawada, Tsuyoshi,Kuwahara, Yutaka,Shosenji, Hideto
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- Synthesis of bis(amidoxime)s and evaluation of their properties as uranyl-complexing agents
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Uranium pollution involves high toxicity and radioactivity and, therefore, constitutes a grave threat to human health and the environment. Chelation is an effective method for sequestering uranium. It is well known that chelators based on oxime groups are able to complex uranyl cations efficiently. To this end, various bis(amidoxime)s were synthesized by reaction of hydroxylamine with the corresponding dinitriles. In these compounds the amidoximes are separated by chains of various lengths, some including a heterocycle (pyridine or 1,3,5-triazine). The abilities of these bis(amidoxime)s to complex uranyl cation in water were evaluated by determining their affinity constants and thermodynamic parameters by means of Isothermal Titration Calorimetry (ITC). DFT calculations were also performed, to determine the optimum structures of the complexes formed between uranyl cations and the oximate groups. A tetrakis(amidoxime), also synthesized in this work, shows good affinity for uranium, and a single molecule is able chelate several uranyl cations. These results are of importance for the remediation of uranium-polluted wastewaters, and open up several perspectives for the design and synthesis of new amidoxime compounds.
- Stemper, Jérémy,Tuo, Wei,Mazarío, Eva,Helal, Ahmed S.,Djurovic, Alexandre,Lion, Claude,El Hage Chahine, Jean-Michel,Maurel, Fran?ois,Hémadi, Miryana,Le Gall, Thierry
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- Coordination-driven self-assembly of palladium(II)-based metallacalixarenes as anion receptors using flexible pyridine-bridged diimidazole ligands
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Two types of palladium(II)-based metallacalixarenes [ML]2+ and [ML2]2+ have been synthesized through coordination-driven self-assembly from a series of flexible pyridine-bridged diimidazole ligands [2,6-bis((1H-imidazol-1-yl)methyl) pyridine (L1), 2,6-bis((1H-benzo[d]imidazol-1-yl)methyl)pyridine (L2), 2,6-bis((1H-naphtho[2, 3-d]imidazol-1-yl)methyl)pyridine (L3)], with palladium(II)-based building blocks [Pd(BF4)2(M1-BF4) and (tmeda)Pd(NO3)2 (M2-NO3) (tmeda = N,N,N′,N′-tetramethyl-ethylenediamine)]. All complexes were characterized by NMR spectroscopy (1H NMR and 13C NMR), mass spectrometry (CSI-MS, ESI-HRMS) and elemental analysis. The single crystal X-ray diffraction analysis of [M1L22](NO3)2, [M1L32](NO3)2, [M1L32](PF6)2 and [M2L3](NO3)2 further confirmed the uniquely single bowl-shape and double bowl-shape structures. The anion binding properties within the metallacalixarenes as receptors were also investigated by NMR titration experiments in DMSO.
- Du, Wutong,Tong, Jin,Deng, Wei,Wang, Mingxue,Yu, Shuyan
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- Design, synthesis, and biological characterization of a new class of symmetrical polyamine-based small molecule CXCR4 antagonists
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CXCR4, a well-studied coreceptor of human immunodeficiency virus type 1 (HIV-1) entry, recognizes its cognate ligand SDF-1α (also named CXCL12) which plays many important roles, including regulating immune cells, controlling hematopoietic stem cells, and directing cancer cells migration. These pleiotropic roles make CXCR4 an attractive target to mitigate human disorders. Here a new class of symmetrical polyamines was designed and synthesized as potential small molecule CXCR4 antagonists. Among them, a representative compound 21 (namely HF50731) showed strong CXCR4 binding affinity (mean IC50 = 19.8 nM) in the CXCR4 competitive binding assay. Furthermore, compound 21 significantly inhibited SDF-1α-induced calcium mobilization and cell migration, and blocked HIV-1 infection via antagonizing CXCR4 coreceptor function. The structure-activity relationship analysis, site-directed mutagenesis, and molecular docking were conducted to further elucidate the binding mode of compound 21, suggesting that compound 21 could primarily occupy the minor subpocket of CXCR4 and partially bind in the major subpocket by interacting with residues W94, D97, D171, and E288. Our studies provide not only new insights for the fragment-based design of small molecule CXCR4 antagonists for clinical applications, but also a new and effective molecular probe for CXCR4-targeting biological studies.
- An, Jing,Fang, Xiong,Huang, Lina S.,Huang, Ziwei,Liang, Boqiang,Meng, Qian,Schooley, Robert T.,Wang, Juan,Xu, Yan,Zhang, Chaozai,Zhang, Huijun,Zhang, Xingquan,Zhu, Siyu
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- Synthesis of unprotected CH2-skipped piperazine-pyridine alternating cycles with azide end-group
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This work describes synthesis of CH2-skipped alternating piperazine-pyridine cycles with azide end-group starting from piperazine, 1-methylpiperazine and pyridine-2,6-dicarboxylic acid. This compound can be used to enhance binding efficiency by shielding repulsion between negatively charged phosphate groups in DNA-oligonucleotide hybridization techniques.
- Kipper, Andi,Kalvet, Indrek,T?mm, Kaido,Sikk, Lauri,Burk, Peeter,Kiv, Kuldar,M?eorg, Uno
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- Rigid Mn(II) chelate as efficient MRI contrast agent for vascular imaging
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The aza-semi-crown pentadentate ligand rigidified by pyridine and piperidine rings was designed and synthesized. It can react with Mn(II) in water to form complex with improved longitudinal relaxivity, leading to efficient signal intensity enhancement of vascular vessels under a clinical magnetic resonance imaging scanner.
- Su, Hongying,Wu, Changqiang,Zhu, Jiang,Miao, Tianxin,Wang, Dan,Xia, Chunchao,Zhao, Xuna,Gong, Qiyong,Song, Bin,Ai, Hua
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- Coumarin-TPA derivative: A reaction-based ratiometric fluorescent probe for Cu(I)
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A coumarin-based reactive probe 1 is reported for the highly selective detection of Cu+. The benzylic ether (C-O) bond of probe 1 can be cleaved selectively by the reaction with Cu+ under a physiological reducing environment, resulting in a fluorescent change. The maximum emission peak exhibited a red shift from 410 nm to 472 nm, and a remarkable enhancement of emission intensity ratios (I472/I410) from 0.26 to 13.82 was observed.
- Yu, Kang-Kang,Li, Kun,Hou, Ji-Ting,Yu, Xiao-Qi
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- Amino-acid templated assembly of sucrose-derived macrocycles
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C2-Symmetrical chiral macrocyles containing two sucrose units were prepared by an amino acid templated macrocyclization reaction between appropriate sucrose-based linear precursors and ethylenediamine.
- Lewandowski, Bartosz,Jarosz, Slawomir
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- A fast, highly selective and sensitive dansyl-based fluorescent sensor for copper (II) ions and its imaging application in living cells
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Since the copper ions (Cu2+) play a fatal role in many foundational physiological processes, it is important to develop a simple, highly sensitive and selective sensor for Cu2+detection in living systems. Herein, an intramolecular charge transfer (ICT) and dansyl-based fluorescent chemosensor 1 was designed, synthesized and characterized for the sensitive and selective quantification of Cu2+. It exhibited remarkable fluorescence quenching upon addition of Cu2+over other selected metal ions, attributed to the complex formation between 1 and Cu2+with the association constant 6.7?×?105?M?1. The sensor 1 showed a fast and linear response towards Cu2+in the concentration range from 0 to 12.5?×?10?6?mol?L?1with the detection limit of 2.5?×?10?7?mol?L?1. This detection could be carried out in a wide pH range of 5.0–14. Furthermore, sensor 1 can be used for detecting Cu2+in living cells.
- Zhou, Ming,Wang, Xiaobo,Huang, Kunzhu,Huang, Yuzhao,Hu, Shou,Zeng, Wenbin
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- Metal organic complex with near-infrared absorption and emission properties and preparation method thereof
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The invention discloses a metal organic complex with near-infrared absorption and emission properties and a preparation method thereof. The metal organic complex is prepared by the following steps of:carrying out condensation reaction on an aldehyde group-containing ligand precursor and thiophene or furan or pyrrole or benzene ring or selenophen to obtain a ligand, and carrying out coordination reaction on the ligand and Pd(DMSO)2Cl2 or Pt(DMSO)2Cl2 to obtain a complex monomer, and carrying out condensation dimerization reaction on the complex monomer to obtain the metal organic complex. Themetal organic complex with near-infrared absorption and emission properties has near-infrared absorption and emission properties, and can be used as a wave-absorbing material in the fields of near-infrared imaging, invisible ink and anti-counterfeiting printing, near-infrared bar code invisible identification, plasma display panels, dye-sensitized solar cells, near-infrared light emitting diodes and the like.
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Paragraph 0110; 0113-0114
(2021/02/24)
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- Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
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Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.
- Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
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p. 2295 - 2301
(2020/05/18)
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- Preparation method of 2,6-chloromethylpyridine hydrochloride (by machine translation)
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The invention belongs to the field, of organic synthesis, and particularly relates to 2,6 -chloromethylpyridine hydrochloride, preparation method :(1), which comprises the following steps 2,6 - reacting,dimethylaminopyridine as a raw material 2,6 - to prepare ;(2)2,6 -picolinic acid dimethyl 2,6 -picolinic acid dimethyl ;(3)2,6 -pyridine dimethanol and thionyl chloride to obtain a target product 2,6 -dichloromethylpyridine dihydrochloride with methanol in an acidic condition ;(4)2,6 - The method comprises the following steps: reacting 2,6 - with a commonly-used chemical raw material containing a pyridine ring and methanol in an acidic condition. The method disclosed by the invention is suitable for industrial, production : (by machine translation)
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- CHELATORS AND METHODS OF MAKING AND USING SAME
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A chelating agent having the general formula (I) is provided (I) Metal chelates and constructs for carrying out targeted radionuclide therapy incorporating such chelating agents are provided. Methods of making and using the chelating agent, metal chelates and constructs for carrying out targeted radionuclide therapy, as well as diagnostic and therapeutic methods using such constructs, are provided.
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Paragraph 0084; 0101
(2020/10/09)
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- Simple synthesis process of intermediate 2,6-pyridinemethanol of pirozadil being platelet aggregation inhibitor
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The invention discloses a simple synthesis process of intermediate 2,6-pyridinemethanol of pirozadil being a platelet aggregation inhibitor. The process includes: taking 2,6-dimethyl pyridine and AIBNas raw materials, adding dichloromethane, stirring, and heating to realize reflux; slowly dropwise adding bromine into reaction liquid; after adding is finished, performing thermal preservation to enable complete reflux reaction; cooling reaction liquid to the room temperature, adding into ice water, stirring, extracting an aqueous phase once by dichloromethane, and combining organic phases; subjecting the organic phases to vacuum concentration to dry, so that a solid is obtained; taking 2,6-dibromomethylpyridine and 30% sodium hydroxide aqueous solution as raw materials, adding ethyl alcohol, and stirring in a reaction bulb; heating reaction liquid to realize reflux, and performing thermal preservation to enable complete reaction; cooling reaction liquid to the room temperature, adding into ice water, stirring, extracting an aqueous phase twice by dichloromethane, and combining organic phases; subjecting the organic phases to vacuum concentration to dry, so that a solid is obtained,wherein the yield is 82.9-88.6%, and a liquid phase is 98%. The simple synthesis process has advantages of simplicity and easiness in acquisition of raw materials, easiness in reaction control, simplicity in aftertreatment and less wastewater, waste gas and industrial residues.
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Paragraph 0028-0033
(2019/04/17)
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- A 2, 6 - dichloro methyl pyridine hydrochloride preparation method (by machine translation)
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The invention belongs to the field of organic synthesis, in particular relates to a 2, 6 - dichloro methyl pyridine hydrochloride of the preparation method, the method comprises the following steps: (1) to 2, 6 - lutidine as a raw material, preparation 2, 6 - pyridine dicarboxylic acid; (2) 2, 6 - pyridine dicarboxylic acid with methanol under acidic conditions to produce the 2, 6 - pyridine dicarboxylic acid dimethyl ester; (3) 2, 6 - pyridine dicarboxylic acid dimethyl ester is reduced to 2, 6 - pyridine-methanol; (4) 2, 6 - pyridine-methanol with thionyl chloride reaction to obtain the target product 2, 6 - dichloro methyl pyridine hydrochloride. The beneficial effect of the invention is: the invention adopts the commonly used chemical raw materials containing a pyridine [...] reaction, reaction steps is small, low cost, low toxicity, high yield, it is suitable for industrial production. (by machine translation)
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- Functionally Versatile and Highly Stable Chelator for 111In and 177Lu: Proof-of-Principle Prostate-Specific Membrane Antigen Targeting
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Here, we present the synthesis and characterization of a new potentially nonadentate chelator H4pypa and its bifunctional analogue tBu4pypa-C7-NHS conjugated to prostate-specific membrane antigen (PSMA)-targeting peptidomimetic (Glu-urea-Lys). H4pypa is very functionally versatile and biologically stable. Compared to the conventional chelators (e.g., DOTA, DTPA), H4pypa has outstanding affinities for both 111In (EC, t1/2 ≈ 2.8 days) and 177Lu (β-,?, t1/2 ≈ 6.64 days). Its radiolabeled complexes were achieved at >98% radiochemical yield, RT within 10 min, at a ligand concentration as low as 10-6 M, with excellent stability in human serum over at least 5-7 days (- complexes (M3+ = In3+, Lu3+, La3+) were dependent on the ionic radii, where the smaller In3+ has the highest pM value (30.5), followed by Lu3+ (22.6) and La3+ (19.9). All pM values are remarkably higher than those with DOTA, DTPA, H4octapa, H4octox, and H4neunpa. Moreover, the facile and versatile bifunctionalization enabled by the p-OH group in the central pyridyl bridge of the pypa scaffold (compound 14) allows incorporation of a variety of linkers for bioconjugation through easy nucleophilic substitution. In this work, an alkyl linker was selected to couple H4pypa to a PSMA-targeting pharmacophore, proving that the bioconjugation sacrifices neither the tumor-targeting nor the chelation properties. The biodistribution profiles of 111In- and 177Lu-labeled tracers are different, but promising, with the 177Lu analogue particularly outstanding.
- Li, Lily,Jaraquemada-Peláez, María De Guadalupe,Kuo, Hsiou-Ting,Merkens, Helen,Choudhary, Neha,Gitschtaler, Katrin,Jermilova, Una,Colpo, Nadine,Uribe-Munoz, Carlos,Radchenko, Valery,Schaffer, Paul,Lin, Kuo-Shyan,Bénard, Fran?ois,Orvig, Chris
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p. 1539 - 1553
(2019/05/22)
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- Efficient Pincer-Ruthenium Catalysts for Kharasch Addition of Carbon Tetrachloride to Styrene
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A series of NNN pincer-ruthenium complexes (R2NNN)RuCl2(PPh3) (R=Cyclohexyl (Cy), t-butyl (tBu), i-propyl (iPr) and phenyl (Ph)) have been synthesized and characterized. These pincer-ruthenium complexes have been used to catalyse the Kharasch addition or atom transfer radical addition (ATRA) of carbon tetrachloride to styrene. Among the pincer-ruthenium catalysts screened for the Kharasch addition, the catalytic activity followed the order (Cy2NNN)RuCl2(PPh3)>(iPr2NNN)RuCl2(PPh3)?(Ph2NNN)RuCl2(PPh3). The oxidation of Ru(II) is easier with (Cy2NNN)RuCl2(PPh3) and (iPr2NNN)RuCl2(PPh3) in comparison with (Formula presented.) RuCl2(PPh3) as indicated by cyclic voltammetry studies. The catalyst precursor (R2NNN)RuCl2(PPh3) itself is the resting state of the reaction. The rate determining step involves the generation of the five-coordinate 16-electron ruthenium(II) species (R2NNN)RuCl2. Owing to weaker binding of triphenyl phosphine to ruthenium, the generation of catalytically active 16-electron species (Cy2NNN)RuCl2 and (iPr2NNN)RuCl2 are more favourable. The complex (Cy2NNN)RuCl2(PPh3) demonstrates very high productivity (5670 turnovers after 48 h at 140 °C) in the absence of any co-catalyst radical initiator. To the best of our knowledge, our turnovers (ca. 5670) are much higher than that reported hitherto. Quantum mechanical calculations demonstrate that the path involving the activation of carbon tetrachloride by (Cy2NNN)RuCl2 is more favoured than the path where carbon tetrachloride is activated by (Cy2NNN)RuCl2(η2-styrene). Density functional theory (DFT) and kinetic studies are in accord with the widely accepted mechanism involving the single electron transfer (SET) from ruthenium(II) to chloride radical with concomitant generation of a benzyl radical which is trapped by the resulting ruthenium(III) species. (Figure presented.).
- Das, Kanu,Dutta, Moumita,Das, Babulal,Srivastava, Hemant Kumar,Kumar, Akshai
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p. 2965 - 2980
(2019/04/30)
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- PROCESSES FOR MAKING TRIAZOLO[4,5D] PYRAMIDINE DERIVATIVES AND INTERMEDIATES THEREOF
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Provided herein are, inter alia, methods for making triazolo[4,5]pyramidine derivatives and intermediates thereof that are useful for treating diseases.
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Paragraph 0322
(2018/10/25)
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- Improved synthesis of symmetrically & asymmetrically: N -substituted pyridinophane derivatives
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The N,N′-di(toluenesulfonyl)-2,11-diaza[3,3](2,6)pyridinophane (TsN4) precursor was sought after as a starting point for the preparation of various symmetric and asymmetric pyridinophane-derived ligands. Various procedures to synthesize TsN4 had been published, but the crucial problem had been the purification of TsN4 from the larger 18- and 24-membered azamacrocycles. Most commonly, column chromatography or other laborious methods have been utilized for this separation, yet we have found an alternate selective dissolution method upon protonation which allows for multi-gram scale output of TsN4·HCl. This optimized synthesis of TsN4 also led to the development of symmetric RN4 derivatives as well as the asymmetric derivative N-(tosyl)-2,11-diaza[3,3](2,6)pyridinophane (TsHN4). Using this TsHN4 precursor, different N-substituents can be added to create a library of asymmetric RR′N4 macrocyclic ligands. These asymmetric RR′N4 derivatives expand the utility of the RN4 framework in coordination chemistry and the ability to study the electronic, steric, and denticity effects of these pyridinophane ligands on the metal center.
- Wessel, Andrew J.,Schultz, Jason W.,Tang, Fengzhi,Duan, Hui,Mirica, Liviu M.
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p. 9923 - 9931
(2017/12/12)
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- ELECTROCHROMIC SINGLE AND TWO-CORE VIOLOGENS AND OPTICAL ARTICLES CONTAINING THEM
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The present invention relates to a group of novel electrochromic materials. More specifically, it relates to electrochromic materials based on either single or two-core viologen systems and the use of these viologen systems as a variable transmittance medium for the manufacture of an optical article, such as an ophthalmic lens.
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Paragraph 0147
(2016/09/12)
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- A Modular Synthesis of Multidentate S-, N- and O-Containing Meta- and Paracyclophanes
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The development of a modular approach to macrocycle assembly has enabled the synthesis of a library of pyridine-based macrocycles possessing multiple donor sites where chirality was readily introduced from (R)- or (S)-alanine, a representative amino acid. The facile, regioselective, nucleophilic ring opening of aziridines by dithiols enabled the synthesis of thioether-based linkers which on subsequent alkylation provided access to optically pure macrocycles. A modular approach to macrocyclic assembly has enabled the synthesis of a library of macrocycles possessing multiple donor sites where chirality was readily introduced from (S)-alanine. Key to this approach was the facile, regioselective, nucleophilic ring opening of aziridines by dithiols followed by macrocylisation under conditions of high dilution.
- Rasheed, Omer K.,Bailey, Patrick D.,Lawrence, Amy,Quayle, Peter,Raftery, James
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supporting information
p. 6988 - 6993
(2015/11/16)
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- NOVEL LACTAM DERIVATIVES HAVING THERAPEUTIC EFFECT ON CANCERS
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The present invention relates to a novel lactam derivative having a cancer therapeutic effect or a pharmaceutically acceptable salt thereof and a pharmaceutical composition containing the same as an active ingredient. The novel lactam derivative in accordance with the present invention is capable of selectively and effectively inhibiting the growth of cancer cells, that is B-cell non-Hodgkinandprime;s lymphoma, thereby being usefully used as a pharmaceutical composition for treating cancer or inhibiting the growth of cancer cells.COPYRIGHT KIPO 2015
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Paragraph 0038-0039; 0080-0082
(2016/11/14)
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- Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines
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The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by 1H NMR spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes.
- Ratjen, Lars,Vantomme, Ghislaine,Lehn, Jean-Marie
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supporting information
p. 10070 - 10081
(2015/07/07)
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- Synthesis, spectroscopic characterization and density functional studies of a bis-benzimidazole derivative and of its complexes with palladium(II) halides
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The 2,6-bis(benzimidazol-2′-ylthiomethyl)pyridine (L) ligand and its palladium(II) complexes [Pd(L)X]X (X = Cl, Br, and I) have been synthesized and characterized by spectroscopic data acquisition. The ligand (L) was prepared by conventional heating as well as by microwave irradiation. Microwave irradiation shows additional features, including an easy workup, a much faster reaction and higher yields. The molar conductivity data reveal that the complexes form a 1:1 electrolyte in DMSO. The geometries, ground-state energetics and vibrational spectra of (L) and of its complexes have been elucidated, in terms of quantum chemical calculations. In the mononuclear complexes, the palladium atom is coordinated to three nitrogen atoms and one terminal halogen atom in a slightly distorted square planar arrangement. The present elemental analyses, FT-IR (mid, far), 1H and 13C NMR spectra are in good accordance with the square planar geometry around the Pd ion. The thermal behaviors of the complexes have been assessed by thermal gravimetric and differential thermal analyses.
- Aghatabay, Naz Mohammed,Altun, Ahmet,Gürbüz, Mustafa Ulvi,Türkyilmaz, Murat
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p. 905 - 912
(2014/08/18)
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- Synthesis, structural aspects, antimicrobial activity and ion transport investigation of five new [1+1] condensed cycloheterophane peptides
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Five novel [1+1] condensed cycloheterophane peptides were synthesized via reaction of pyridine-2,6-bis(2-aminothiophenoxymethyl) with several diacid chlorides: glutaryl dichloride, adipoyl dichloride, 2,2′-thiodiacetyl chloride, dithiodiglycoloyl chloride and 3,3′-thiodipropionoyl chloride combinations (L 1 -L 5 ). The compounds were characterized by elemental analyses, mass, FT-IR, 1H, and 13C NMR spectral data. The antimicrobial activities of the compounds were evaluated using the disk diffusion method in dimethyl sulfoxide as well as the minimal inhibitory concentration dilution method, against several bacteria and yeast cultures. The results were compared with those of commercial antibiotic and antifungal agents. Structure activity relationships were also discussed. Permeability of compound L 5 against Na+ and K+ were also investigated. Graphical abstract: Five novel cycoloheterophane amides were synthesized. Mass spectra reveal their [1+1] cyclic condensation. The compounds exert moderate microbial activity. Thia and aza groups seem to be a key element of microbial potency.[Figure not available: see fulltext.]
- Zaim, Oemer,Aghatabay, Naz Mohammed,Guerbuez, Mustafa Ulvi,Baydar, Caglar,Duelger, Basaran
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p. 151 - 159
(2014/03/21)
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- A general synthesis of bis-α-acyloxy-1,4- and -1,5-diketones through catalytic oxidative opening of acylated THF and THP diols
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The first general synthesis of bis-α-acyloxy-1,4- and -1,5-diketones has been accomplished in a catalytic oxidative opening of bis-acylated THF and THP (tetrahydropyran) diols, which were synthesised by osmium- or ruthenium-catalysed oxidative cyclisation of 1,5- and 1,6-dienes. The overall sequence corresponds to the regioselective double ketoacyloxylation of the starting diene. The synthesised bis-α-acyloxy-1,5-dicarbonyl compounds have been transformed into pyridine-based oxido pincer ligands or pyrazinedimethanol substances, leading to the discovery of unprecedented aromatisation routes. The first general synthesis of bis-α-acyloxy-1,4- and -1,5-diketones is reported. The process features the catalytic oxidative opening of bis-acylated THF and THP diols, which were synthesised by the transition-metal-mediated oxidative cyclisation of 1,5- and 1,6-dienes. The 1,5-diketone products were cyclised to give pyridinedimethanol derivatives. New aromatisation modes have been disclosed. Copyright
- Piccialli, Vincenzo,D'Errico, Stefano,Borbone, Nicola,Oliviero, Giorgia,Centore, Roberto,Zaccaria, Sabrina
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p. 1781 - 1789
(2013/04/10)
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- Immobilized into montmorillonite Mn(II) complexes of novel pyridine schiff-base ligands and their catalytic reactivity in epoxidation of cyclohexene with O2
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Mild temperature and atmospheric oxygen pressure assisted epoxidation of cyclohexene was achieved with a series of novel montmorillonite-supported Mn(II) complexes of pyridine Schiff-base ligands. The catalysts were characterized by IR, UV-Vis DRS, XRD, SEM and ICP. The heterogeneous catalysts were proved to promote the epoxidation of cyclohexene efficiently, affording the desired product epoxycyclohexane with a yield up to 92 %. The effects of various reaction conditions on the catalytic reaction were optimized. Repeated runs indicated that the catalysts were stable for 3 cycles without noticeable loss of their catalytic activity.
- Li, Zhongying,Tang, Ruiren,Liu, Guiyin
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p. 592 - 599
(2013/07/19)
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- Novel pyridine Schiff base-manganese(ii) complexes: Synthesis, characterization and catalytic reactivity of the epoxidation of cyclohexene
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Four novel pyridine Schiff bases derived from 2,6-pyridinedicarbaldehyde and substituted o-hydroxyl-aromatic amines and their manganese(ii) complexes were synthesized and characterized by elemental analyses, ESI-MS analysis, thermal analysis (TGA), H-NMR, IR and UV-vis. The activity of these complexes as catalysts in cyclohexene autoxidation were investigated and the effects of various reaction conditions on the catalytic reaction were optimized to obtain as high as 99.6% conversion with 95.0% selectivity of epoxycyclohexane at 40°C for 6 h using molecular oxygen as an oxidant in acetonitrile. The result presents excellent catalysts for epoxidation of cyclohexene under mild temperature and atmospheric oxygen (O2) pressure.
- Li, Zhongying,Liu, Changhui,Tang, Ruiren,Liu, Guiyin
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p. 9745 - 9751
(2013/09/02)
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- H4octapa: An acyclic chelator for 111In radiopharmaceuticals
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This preliminary investigation of the octadentate acyclic chelator H 4octapa (N4O4) with 111In/ 115In3+ has demonstrated it to be an improvement on the shortcomings of the current industry "gold standards" DOTA (N 4O4) and DTPA (N3O5). The ability of H4octapa to radiolabel quantitatively 111InCl3 at ambient temperature in 10 min with specific activities as high as 2.3 mCi/nmol (97.5% radiochemical yield) is presented. In vitro mouse serum stability assays have demonstrated the 111In complex of H 4octapa to have improved stability when compared to DOTA and DTPA over 24 h. Mouse biodistribution studies have shown that the radiometal complex [111In(octapa)]- has exceptionally high in vivo stability over 24 h with improved clearance and stability compared to [ 111In(DOTA)]-, demonstrated by lower uptake in the kidneys, liver, and spleen at 24 h. 1H/13C NMR studies of the [In(octapa)]- complex revealed a 7-coordinate solution structure, which forms a single isomer and exhibits no observable fluxional behavior at ambient temperature, an improvement to the multiple isomers formed by [In(DTPA)]2- and [In(DOTA)]- under the same conditions. Potentiometric titrations have determined the thermodynamic formation constant of the [In(octapa)]- complex to be log KML = 26.8(1). Through the same set of analyses, the [111/115In(decapa)] 2- complex was found to have nonoptimal stability, with H 5decapa (N5O5) being more suitable for larger metal ions due to its higher potential denticity (e.g., lanthanides and actinides). Our initial investigations have revealed the acyclic chelator H 4octapa to be a valuable alternative to the macrocycle DOTA for use with 111In, and a significant improvement to the acyclic chelator DTPA.
- Price, Eric W.,Cawthray, Jacqueline F.,Bailey, Gwendolyn A.,Ferreira, Cara L.,Boros, Eszter,Adam, Michael J.,Orvig, Chris
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experimental part
p. 8670 - 8683
(2012/06/29)
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- AROMATIC COMPOUND, MODIFICATION CARRIER THAT USES SAME AND IS USED FOR SYNTHESIZING AN OLIGONUCLEOTIDE DERIVATIVE, OLIGONUCLEOTIDE DERIVATIVE, AND OLIGONUCLEOTIDE CONSTRUCT
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The present invention provides an oligonucleotide derivative that enables to easily synthesize an oligonucleotide derivative chemically modified at the 3'-end with two moieties each having a benzene or pyridine structure with a few steps, an aromatic compound serving as a precursor for preparing the modification carrier for synthesizing oligonucleotide derivative, and the oligonucleotide derivative and the oligonucleotide construct using the same, that is chemically modified at the 3'-end with two moieties each having a benzene or pyridine structure, and has good permeability through a cell membrane and excellent nuclease resistance. The modification carrier for synthesizing oligonucleotide derivative, comprising a unit and a carrier carrying the unit directly or via a linker, wherein the unit is represented by the formula (a): wherein, R1 to R6 each independently represent hydrogen or a substituent other than hydrogen; Z1 and Z2 each independently represent CH or nitrogen; and X represents oxygen or sulfur.
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Page/Page column 16
(2012/11/06)
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- Synthesis of nuclease-resistant siRNAs possessing universal overhangs
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RNA interference (RNAi) induced by small interfering RNA (siRNA) has emerged as a powerful technique for the silencing of gene expression at the post-transcriptional level. It has been shown that in the RNAi machinery, the 3′-overhang region of a guide strand (an antisense strand) of siRNA is recognized by the PAZ domain in the Argonaute protein, and the 2-nucleotide (nt) 3′-overhang is accommodated into a binding pocket composed of hydrophobic amino acids in the PAZ domain. Based on this background information, we designed and synthesized siRNAs possessing aromatic compounds at their 3′-overhang regions. It was found that the modified siRNAs possessing aromatic compounds are more potent than the siRNAs without the 3′-overhang regions. Further, the silencing activities of the modified siRNAs are almost equal to those of normal siRNAs with natural nucleosides at their 3′-overhang regions. We also found that the siRNAs possessing the aromatic compounds at their 3′-overhang region could be used to inhibit hepatitis C virus (HCV) replication. Moreover, the RNAs with aromatic groups at their 3′-ends were more resistant to nucleolytic degradation by snake venom phosphodiesterase (SVPD) (a 3′-exonuclease) than natural RNAs. The aromatic compounds described in this report do not have functional groups capable of forming hydrogen bonds with nucleobases. Therefore, we expect that they can serve as the universal overhang units that can improve the nuclease resistance of siRNAs.
- Ueno, Yoshihito,Watanabe, Yuuji,Shibata, Aya,Yoshikawa, Kayo,Takano, Takashi,Kohara, Michinori,Kitade, Yukio
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experimental part
p. 1974 - 1981
(2009/05/07)
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- Improved synthesis of a C3-symmetrical pyridinophane
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The formation of the C3-symmetrical 2,11,20-triaza[3.3.3](2,6)pyridinophane 1 was undertaken with the aim of improving the synthesis of this highly desirable macrocycle, with the future aim of functionalizing 1 with amide pendent arms for the recognition of lanthanide ions. The synthesis of 1 involves the stepwise transformation of pyridine-2,6-dicarboxylic acid into two key intermediates; N,N-bis[(6-hydroxymethyl)pyridin-2-yl]-p-tosylamide 7 and 6-bis[(amino-p-tosyl)methyl]pyridine 5. The macrocyclization of these two intermediates gave 8, from which 1 was formed upon deprotection of the three tosyl groups.
- Nolan, Claire,Gunnlaugsson, Thorfinnur
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p. 1993 - 1996
(2008/09/19)
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- Binding of secondary dialkylammonium salts by pyrido-21-crown-7
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Pyrido-21-crown-7 (P21C7) has been synthesized and shown to form [2]pseudorotaxanes spontaneously with secondary dialkylammonium ions. These complexes are stronger than their benzo-21-crown-7 counterparts and much stronger than their dibenzo-24-crown-8 counterparts. Based on this new P21C7/secondary dialkylammonium salt recognition motif, a [2]rotaxane terminated by phenyl groups as stoppers has been successfully constructed using the threading-followed-by-stoppering technique.
- Zhang, Chuanju,Zhu, Kelong,Li, Shijun,Zhang, Jinqiang,Wang, Feng,Liu, Ming,Li, Ning,Huang, Feihe
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supporting information; experimental part
p. 6917 - 6920
(2009/04/07)
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- Synthesis and determination of alkali metal binding selectivities of chiral macrocyclic bisamides derived from D-mannitol and L-threitol possessing 2,6-pyridinedicarboxamide subunits
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Five chiral macrocyclic bisamides derived from d-mannitol and l-threitol, possessing C2 symmetry, were obtained by a macrocyclization reaction under two different conditions (MeOH, 12 kbar, rt or MeONa/MeOH, 1 bar, rt). Their applications for alkali metal binding processes are studied using ESI-MS technique.
- Gruza, Mariusz M.,Pokrop, Arletta,Jurczak, Janusz
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p. 1939 - 1946
(2007/10/03)
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- Copper(II) complexes of 6-hydroxymethyl-substituted tris(2-pyridylmethyl)amine ligands
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Three potentially tripodal, tris(2-pyridylmethyl)amine (tpa) ligands with hydroxymethyl substituents, [6-(hydroxymethyl)-2-pyridylmethyl]bis(2-pyridylmethyl)amine (HL1), bis[6-(hydroxymethyl)-2-pyridylmethyl]-2-(pyridylmethyl)amine (H2L2), tris[6-(hydroxymethyl)-2-pyridylmethyl]amine (H3L3), have been prepared in good yields. From these ligands, the copper(II) co-ordination complexes [Cu(HL1)Cl]Cl 1, [Cu(H2L2)Cl]X (X=Cl 2 or p-toluenesulfonate 3), [Cu(L2BF2)][BF4] 4 a complex of a novel macrocyclic anion with a tpa core, [Cu(H3L3)Br0.43Cl0.57)2(Br0.97Cl0.03)2] 5 with compositionally disordered bromo and chloro co-ligands, [Cu(H3L3)Br]Br 6 and the unusual trimer [Cu3{H3(L3)2}Br][BF4]2 7 have been synthesized and their spectroscopic and redox properties and crystal structures obtained.
- He, Zhicong,Chaimungkalanont, P. Jinny,Craig, Donald C.,Colbran, Stephen B.
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p. 1419 - 1430
(2007/10/03)
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- A new efficient method for the preparation of 2,6-pyridinedimethyl ditosylates from dimethyl 2,6-pyridinedicarboxylates
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We report here an efficient method for the preparation of 2,6- pyridinedimethyl ditosylate and four of its 4-substituted derivatives, two of them have not been reported in the literature. We also describe here a modification of the reported synthesis for chelidonic and chelidamic acids with improved yields and higher purity.
- Horváth, Gy?rgy,Rusa, Cristian,K?nt?s, Zoltán,Gerencsér, János,Huszthy, Péter
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p. 3719 - 3731
(2007/10/03)
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- Macrocyclic Dioxo Pentaamines: Novel Ligands for 1:1 Ni(II)-O2 Adduct Formation
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Substituted and unsubstituted macrocyclic dioxo pentaamines, 1,4,7,10,13-pentaazacyclohexadecane-14,16-dione, form stable 1:1 square-pyramidal complexes with Ni(II) and Cu(II), which possess two deprotonated amide donors in equatorial positions.The high-spin Ni(II) complexes show a very low Ni(II,III) redox potential of +0.24 V vs.SCE and are easily oxidized chemically or electrochemically to Ni(III) complexes.Moreover, the Ni(II) complexes react with molecular oxygen to form 1:1 Ni(II)-O2 adducts in aqueous solution, as established by a combination of polarographic, spectrophotometric, and manometric methods.Comparative studies with relevant pentadentate macrocyclic polyamine complexes revealed that the two deprotonated amide groups and the fifth amine donor incorporated in the 16-membered macrocyclic frame are essential for the formation of the Ni(II)-O2 adducts.The oxygen uptake reaction is first order in and in -2L>0 in aqueous solutions, and the second-order rate constant is 1.7*102 s-1 M-1 at 35 deg C.The attack of O2 at the sixth coordinate site is competitively inhibited by imidazole.The O2 complexation constant KO2 is determined to be 1.9*104 M-1 at 35 deg C by potentiometric titration.Novel features of the Ni(II)-O2 adducts are discussed.
- Kimura, Eiichi,Machida, Ryosuke,Kodama, Mutsuo
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p. 5497 - 5505
(2007/10/02)
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- SEQUENCE OF REPLACEMENT OF HYDROGEN IN 2,6-DIMETHYLPYRIDINE BY LITHIUM OR HALOGEN
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It is shown that, according to the results of chromatographic mass spectrometry, the reaction of 2,6-dimethylpyridine with phenyllithium leads only to the monolithium derivative.The chlorination and bromination of 2,6-dimethylpyridine with various reagents were studied systematically.A method for the conversion of 2,6-bis(chloromethyl)pyridine to 2,6-bis(hydroxymethyl)pyridine is given.
- Karpman, Ya.S.,Azimov, V.A.,Anisimova, O.S.,Yakhontov, L.N.
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