34984-16-2Relevant academic research and scientific papers
Formation of very stable and selective Cu(II) complexes with a non-macrocyclic ligand: Can basicity rival pre-organization?
Abada, Sabah,Lecointre, Alexandre,Elhabiri, Mourad,Charbonniere, Loic J.
, p. 9055 - 9062 (2010)
The synthesis of ligand L based on a 2,6-bis[(N,N-bis(methylene phosphonic acid)aminomethyl] pyridine scaffold is described. Potentiometry combined with UV-Vis absorption spectrophotometric titrations were used to determine the protonation constants of the ligand and the stability constants of its corresponding Cu(II), Ni(II), Zn(II) and Ga(III) cations (0.1 M NaClO 4, 25.0 °C). The physico-chemical approach revealed very large stability constants for Cu(II) complexation (logKCuL = 22.71(7)) reflected in a very high pCuII value of ～ 15.5 (pH = 7.4, [L]tot = 10-5 M, [Cu]tot = 10-6 M), close to those measured for the strong methylphosphonate functionalized cyclen chelators. Based on a literature survey, a correlation is proposed between the pK values of branched polyamine ligands and their stability constants for Cu(II) complexation, allowing for an estimation of the latter on the basis of the protonation constants of L. Ligand L was also shown to be very selective towards Cu(II) compared to the other cations studied (ΔlogK > 4). UV-Vis spectroscopy and kinetic measurements indicated that the formation of the cupric complexes with L is very fast, which, in combination with all other properties, makes it an excellent non-cyclic target for Cu(II) radiopharmaceutical within the frame of 64Cu positron emission tomography imaging and radiotherapy. The Royal Society of Chemistry 2010.
Oxygen reduction catalyzed by a water-soluble binuclear copper(ii) complex from a neutral aqueous solution
Liu, Chengyu,Lei, Haitao,Zhang, Zongyao,Chen, Fangfang,Cao, Rui
, p. 3189 - 3192 (2017)
A water-soluble binuclear CuII complex, synthesized using a polypyridine-polyamide ligand, was able to catalyze oxygen reduction to water from neutral aqueous solutions. Electrocatalytic results suggested that one CuII center was first reduced by one electron to form a CuIICuI species, which reacted with O2 to give a superoxide radical intermediate.
Assisted π-stacking: a strong synergy between weak interactions
Sao, Soumik,Naskar, Sumit,Mukhopadhyay, Narottam,Das, Mousumi,Chaudhuri, Debangshu
, p. 12186 - 12189 (2018)
Synergy between a pair of weak non-covalent interactions can predispose a molecular self-assembly towards a specific pathway. We report assisted π-stacking, a synergy between aromatic π-stacking and n → π* interactions that exhibits an unprecedented strength and thermal stability. Natural bond orbital analysis reveals the non-additive nature of the interaction.
Well-defined Aryl-FeII complexes in cross-coupling and C?H activation processes
Magallón, Carla,Planas, Oriol,Roldán-Gómez, Steven,Luis, Josep M.,Company, Anna,Ribas, Xavi
, p. 1195 - 1200 (2021/04/06)
Herein we explore the intrinsic organometallic reactivity of iron embedded in a tetradentate N3C macrocyclic ligand scaffold that allows the stabilization of aryl-Fe species, which are key intermediates in Fe-catalyzed cross-coupling and C?H functionalization processes. This study covers C?H activation reactions using MeLH and FeCl2, biaryl C?C coupling product formation through reaction with Grignard reagents, and cross-coupling reactions using MeLBr or HLBr in combination with Fe0(CO)5. Synthesis under light irradiation and moderate heating (50 °C) affords the aryl-FeII complexes [FeII(Br)(MeL)(CO)] (1Me) and [FeII(HL)(CO)2]Br (1H). Exhaustive spectroscopic characterization of these rare low-spin diamagnetic species, including their crystal structures, allowed the investigation of their intrinsic reactivity.
XYLYLENEDIAMINE COMPOSITION AND METHOD OF PRODUCING POLYAMIDE RESIN
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Paragraph 0062, (2018/08/30)
The invention provides [1] a xylylenediamine composition containing a xylylenediamine and a pyridine compound (A) having at least one substituent which contains an amino group, wherein the amount of the pyridine compound (A) is from 0.001 to 0.1 parts by mass per 100 parts by mass of the xylylenediamine; and [2] a method of producing a polyamide resin having a step in which a pyridine compound (A) having at least one substituent which contains an amino group, a diamine including a xylylenediamine (but excluding diamines which correspond with the pyridine compound (A)) and a dicarboxylic acid are introduced into a reaction system and subjected to a polycondensation reaction, wherein the amount added of the pyridine compound (A) is from 0.001 to 0.1 parts by mass per 100 parts by mass of the xylylenediamine.
An example of unusual pyridine donor Schiff base uranyl (UO22+) complexes
Hardy,Wyss,Eddy,Gorden
supporting information, p. 5718 - 5720 (2017/07/11)
The pentadentate coordination environment of a 2,6-bis[1-[(2-hydroxyphenyl)imino]ethyl] pyridine ligand scaffold was designed to accommodate the larger atomic radius of uranium as the uranyl dioxo cation, while fully occupying its equatorial plane. Here, two new uranyl (UO22+) complexes utilizing this scaffold have been synthesized from successive condensation reactions and subsequent metal complexation. Surprising Zn fluorescence is also discussed.
A CuI/CuIII prototypical organometallic mechanism for the deactivation of an active pincer-like CuI catalyst in Ullmann-type couplings
Rovira, Mireia,Ja?íková, Lucie,Andris, Erik,Acu?a-Parés, Ferran,Soler, Marta,Güell, Imma,Wang, Ming-Zheng,Gómez, Laura,Luis, Josep M.,Roithová, Jana,Ribas, Xavi
supporting information, p. 8786 - 8789 (2017/08/09)
Unraveling the mechanistic details of copper-catalyzed arylation of nucleophiles (Ullmann-type couplings) is a very challenging task. It is a matter of intense debate whether it is a radical-based process or an organometallic redox-based process. The ancillary ligand choice in Ullmann-type couplings plays a key role in such transformations and can strongly influence the catalytic efficiency as well as the mechanism. Here, we show how a predesigned tridentate pincer-like catalyst undergoes a deactivation pathway through a CuI/CuIII prototypical mechanism as demonstrated by helium-tagging infrared photodissociation (IRPD) spectroscopy and DFT studies, lending a strong support to the existence of an aryl-CuIII species in the Ullmann couplings using this tridentate ligand.
Improved synthesis of symmetrically & asymmetrically: N -substituted pyridinophane derivatives
Wessel, Andrew J.,Schultz, Jason W.,Tang, Fengzhi,Duan, Hui,Mirica, Liviu M.
, p. 9923 - 9931 (2017/12/12)
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.
Synthesis and f-element ligation properties of NCMPO-decorated pyridine N-oxide platforms
Ouizem, Sabrina,Rosario-Amorin, Daniel,Dickie, Diane A.,Paine, Robert T.,De Bettencourt-Dias,Hay, Benjamin P.,Podair, Julien,Delmau, Laetitia H.
, p. 8368 - 8386 (2014/06/09)
Stepwise syntheses of 2-{[2-(diphenylphosphoryl)acetamido]methyl}pyridine 1-oxide, 2-[Ph2P(O)CH2C(O)N(H)CH2]C 5H4NO (6), 2-{[2-(diphenylphosphoryl)acetamido]methyl}-6- [(diphenylphosphoryl)methyl]pyri
Probing the steric and electronic characteristics of a new bis-pyrrolide pincer ligand
Komine, Nobuyuki,Buell, Rene W.,Chen, Chun-Hsing,Hui, Alice K.,Pink, Maren,Caulton, Kenneth G.
, p. 1361 - 1369 (2014/03/21)
A new pincer ligand is synthesized to be dianionic, with the potential to be redox active. It has pyrrrole rings attached to both ortho sites of a pyridine, as the linking element. This H2L can be doubly deprotonated and then used to replace two chloride ligands in MCl2(NCPh) 2, to form LM(NCPh) for M = Pd, Pt. The acid form H2L reacts with ZnEt2 with elimination of only 1 mol of ethane to yield (HL)ZnEt, a three-coordinate species with one pendant pyrrole NH functionality. This molecule binds the Lewis base p-dimethylaminopyridine (DMAP) to give first a simple 1:1 adduct that eliminates ethane on heating to form four-coordinate LZn(DMAP), which has an unusual structure due to the strong preference of the pincer ligand to bind in a mer (planar) geometry. A molecule with two HL - ligands each bonded in a bidentate manner to FeCl2 is synthesized and shown to contain four-coordinate iron with a flattened-tetrahedral structure. The electrochemistry of LM(NCPh) and (L)Zn(DMAP) shows three oxidation processes, which is interpreted to involve at least two oxidations of the pyrrolide arms.
