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21.
Emmanuel Blas Patricio-Rangel Margarita Tlahuextl Hugo Tlahuext Antonio Rafael Tapia-Benavides 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(4):322-327
The synthesis and characterization of two new 1,3,5‐triazines containing 2‐(aminomethyl)‐1H‐benzimidazole hydrochloride as a substituent are reported, namely, 2‐{[(4,6‐dichloro‐1,3,5‐triazin‐2‐yl)amino]methyl}‐1H‐benzimidazol‐3‐ium chloride, C11H9Cl2N6+·Cl? ( 1 ), and bis(2,2′‐{[(6‐chloro‐1,3,5‐triazine‐2,4‐diyl)bis(azanediyl)]bis(methylene)}bis(1H‐benzimidazol‐3‐ium)) tetrachloride heptahydrate, 2C19H18ClN92+·4Cl?·7H2O ( 2 ). Both salts were characterized using single‐crystal X‐ray diffraction analysis and IR spectroscopy. Moreover, the NMR (1H and 13C) spectra of 1 were obtained. Salts 1 and 2 have triclinic symmetry (space group P) and their supramolecular structures are stabilized by hydrogen bonding and offset π–π interactions. In hydrated salt 2 , the noncovalent interactions yield pseudo‐nanotubes filled with chloride anions and water molecules, which were modelled in the refinement with substitutional and positional disorder. 相似文献
22.
Alberto Fernández Jesús J. Fernández Margarita López-Torres José M. Vila 《Journal of organometallic chemistry》2005,690(16):3669-3679
Reaction of the ligand C6H5N(H)NCMe(C5H4N) (a) with palladium(II) acetate in toluene gave the mononuclear cyclometallated complex [Pd{C6H4N(H)NCMe(C5H4N)}(AcO)] (1a). Reaction of 1a with sodium chloride gave the analogous chlorine compound [Pd{C6H4N(H)NCMe(C5H4N)}(Cl)] (3a) which could also be prepared by reaction of a with lithium tetrachloropalladate and sodium acetate in methanol for 48 h; whereas shorter reaction times afforded the non-cyclometallated complex [Pd{C6H5N(H)NCMe(C5H4N)}(Cl)2] (2a). Reaction of the ligand 2-ClC6H4N(H)NCMe(C5H4N) · HCl (b), with palladium(II) acetate, or with lithium tetrachloropalladate and sodium acetate, yielded the cyclometallated complex [Pd2-ClC6H3N(H)NCMe(C5H4N)(Cl)] (1b). Treatment of 3a and 1b with silver trifluoromethanesulphonate (triflate) and triphenylphosphine in acetone gave the mononuclear complexes [Pd{2-RC6HnN(H)NCMe(C5H4N)}(PPh3)][CF3SO3], (R = H, n = 4, 4a; R = Cl, n = 3, 2b) with the ligand as C,N,N′ terdentate and substitution of chlorine by triphenylphosphine. Reaction of 3a and 1b with silver triflate and the tertiary diphosphine Ph2P(CH2)4PPh2 (dppb) in a 2:1 molar ratio gave the dinuclear cyclometallated complexes [{Pd[2-RC6H3N(H)NCMe(C5H4N)]}2(μ-Ph2P(CH2)4PPh2)][CF3SO3]2 (R = H, 5a; R = Cl, 3b) with a μ2-diphosphine bridging ligand. Similarly, treatment of 3a and 1b with silver triflate and the tertiary triphosphines MeC(CH2PPh2)3 (tripod) and (Ph2PCH2CH2)2PPh (triphos), in 3:1 molar ratio, gave the novel trinuclear complexes [{Pd[C6H4N(H)NCMe(C5H4N)]}3{μ3-MeC(CH2Ph2)3}][CF3SO3]3 (6a) and [{Pd[2-ClC6H3N(H)NCMe(C5H4N)]}3{μ3-(PPh2CH2CH2)2PPh}][CF3SO3] 3 (4b) regioselectively, with the phosphine as a μ3-bridging ligand. When the reaction between 3a and triphos was carried out in 1:1 molar ratio the mononuclear complex [Pd{C6H4N(H)NCMe(C5H4N)}{(PPh2CH2CH2)2PPh-P,P,P}][ClO4] (7a) was obtained. The crystal structures of 2b, 3a and 4a have been determined by X-ray crystallography. 相似文献
23.
Margarita Acevedo Alain Fradet 《Journal of polymer science. Part A, Polymer chemistry》1993,31(3):817-830
2,2′-Bis(4,4-dimethyl-5(4H)-oxazolone) ( B3 ) and 2,2′-(1,2-ethylene)-bis(4,4-dimethyl-5(4H)oxazolone) ( B4 ) have been reacted in the bulk with α, ω-diamino polyamide-12 ( PA12 ) of M?n = 1000. The reactions have been studied by SEC, and 1H- and 13C-NMR and resulting polymers characterized by DSC and TGA. The chain coupling reaction is fast and gives high molar mass polymers within 10 min at 200°C with B4 while some side reactions occur with B3 leading to polymers of lower molar mass. The crystallinity of resulting polymers is lower than that of starting oligomer. However, the thermal stability is higher. Model reactions using B3 or B4 and hexamethylene diamine or 1-dodecanamine have been carried out and studied. An intramolecular cyclodehydration giving 2-imidazolin-5-ones takes place during the reactions. Higher cyclization extent is found in the presence of amino group excess. 2-Imidazolin-5-one heterocyclic structures are also observed in the chains of the polymers obtained from PA12 and B3 or B4 . © 1993 John Wiley & Sons, Inc. 相似文献
24.
Josep Castells Elisabet Duñach Fernando Geijo Francisco López-Calahorra Margarita Prats Olga Sanahuja Laura Villanova 《Tetrahedron letters》1980,21(23):2291-2294
Triethylamine catalyzed Michael additions of benzoins to chalcone can prevail over the expected Michael-Stetter additions when certain thiazolium ion conjugate bases - prepared from the pertinent thiazolium salts and triethylamine- are used as catalysts. 相似文献
25.
It is known that full Peano Arithmetic does not have the jointembedding property(JEP). At the other extreme of the hierarchy,Open Induction also fails to have this property. We prove, using some conservation results about fragments ofarithmetic, that if T is a theoryconsistent with PA and T I (bounded existential parameter-freeinduction), then any two m dels of PA which jointly embed ina model of T also jointly embed in an elementary extension ofone of them. In particular, any fragment of PA extending I fails to have JEP. 相似文献
26.
Mercedes Cano JosV. Heras M.Luz Gallego Josefina Perles Caridad Ruiz‐Valero Elena Pinilla M.Rosario Torres 《Helvetica chimica acta》2003,86(9):3194-3203
Two new (η3‐allyl)palladium complexes containing the ligand 3,5‐dimethyl‐4‐nitro‐1H‐pyrazole (Hdmnpz) were synthesized and characterized as [Pd(η3‐C3H5)(Hdmnpz)2]BF4 ( 1 ) and [Pd(η3‐C3H5)(Hdmnpz)2]NO3 ( 2 ). The structures of these compounds were determined by single‐crystal X‐ray diffraction to evaluate the intermolecular assembly. Each complex exhibits similar coordination behavior consistent with cationic entities comprised of two pyrazole ligands coordinated with the [Pd(η3‐C3H5)]+ fragment in an almost square‐planar coordination geometry. In 1 , the cationic entities are propagated through strong intermolecular H‐bonds formed between the pyrazole NH groups and BF ions in one‐dimensional polymer chains along the a axis. These chains are extended into two‐dimensional sheet networks via bifurcated H‐bonds. New intermolecular interactions established between NO2 and Me substituents at the pyrazole ligand of neighboring sheets give rise to a three‐dimensional network. By contrast, compound 2 presents molecular cyclic dimers formed through N? H???O H‐bonds between two NO counterions and the pyrazole NH groups of two cationic entities. The dimers are also connected to each other through C? H???O H‐bonds between the remaining O‐atom of each NO ion and the allyl CH2 H‐atom. Those interactions expand in a layer which lies parallel to the face (101). 相似文献
27.
POSTIRRADIATION PROPERTIES OF A UV-SENSITIVE VARIANT OF CHO 总被引:1,自引:0,他引:1
Richard D. Wood Margarita De Veciana Bonnie Presson -Tincknell 《Photochemistry and photobiology》1982,36(2):169-174
Abstract A UV-hypersensitive mutant of Chinese hamster ovary (CHO) cells, termed 43-3B, has been used in a comparative study with the wild type CHO in order to determine the involvement of repair in several postirradiation phenomena. 43-3B has the same growth rate and chromosome number as the wild type CHO-9. It is hypersensitive to UV irradiation (D0 of 0.3 J/m2 as compared to 3.2 J/m2 for the wild type). 43-3B shows only about 17% of the UV-stimulated unscheduled DNA repair synthesis of CHO-9 as measured by autoradiography. When breaks in supercoiled chromatin are measured after UV by the nucleoid sedimentation method, the mutant appears to be capable of carrying out only limited incision. A much reduced ability to recover control rates of semiconservative DNA synthesis after UV irradiation was observed in the repair-deficient 43-3B cell line, suggesting that the removal of UV-induced replication blocks by excision repair is the most important factor in allowing recovery of UV-inhibited DNA synthesis. Recovery of colony-forming ability between fractionated UV exposures was observed in the wild type CHO-9, but little recovery was seen in 43-3B. This indicates that excision repair capability can also be important in split-fluence recovery. 相似文献
28.
Bernabé-Pineda M Ramírez-Silva MT Tapia-Benavides R Rojas-Hernández A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(5):1071-1076
The importance assigned to chelating agents in diverse areas has impelled studies concerning their development as related to metal ions representing a biological concern. The synthesis of di-isopropyliminodiacetoamide (D) is presented in this work. The acidity constant obtained for D was pKa = 5.79 +/- 0.04 with the aid of program SUPERQUAD. The equilibrium constants for D with Cu(II) were obtained with the aid of program SQUAD for CuD2+ and CuD2(2)+ species giving log beta1 = 4.795 +/- 0.002 and log beta2 = 8.374 +/- 0.004, respectively. 相似文献
29.
Ivan M. Kumanyaev Margarita A. Lapitskaya Ljudmila L. Vasiljeva Kasimir K. Pivnitsky 《Mendeleev Communications》2012,22(3):129-131
The stable pyridinium salt of o-iodoxybenzoic acid (PIBX) that is easy to obtain can serve as a convenient substitute of IBX as an oxidant. PIBX is safer, has neutral properties behaves as an equivalent to IBX in the oxidation of alcohols to ketones or aldehydes in polar solvents (DMF, DMSO), and provides higher oxidation rate in THF due to better solubility. 相似文献