33941-15-0Relevant articles and documents
Effects of metal ions on physicochemical properties and redox reactivity of phenolates and phenoxyl radicals: Mechanistic insight into hydrogen atom abstraction by phenoxyl radical-metal complexes
Itoh,Kumei,Nagatomo,Kitagawa,Fukuzumi
, p. 2165 - 2175 (2001)
Phenolate and phenoxyl radical complexes of a series of alkaline earth metal ions as well as monovalent cations such as Na+ and K+ have been prepared by using 2,4-di-tert-butyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl) phenol (L1H) and 2,4-di-tert-butyl-6-(1,4,7,10,13-pentaoxa-16-aza-cyclo-octadec-16-ylmethyl) phenol (L2H) to examine the effects of the cations on the structure, physicochemical properties and redox reactivity of the phenolate and phenoxyl radical complexes. Crystal structures of the Mg2+- and Ca2+-complexes of L1- as well as the Ca2+- and Sr2+-complexes of L2- were determined by X-ray crystallographic analysis, showing that the crown ether rings in the Ca2+-complexes are significantly distorted from planarity, whereas those in the Mg2+- and Sr2+-complexes are fairly flat. The spectral features (UV-vis) as well as the redox potentials of the phenolate complexes are also influenced by the metal ions, depending on the Lewis acidity of the metal ions. The phenoxyl radical complexes are successfully generated in situ by the oxidation of the phenolate complexes with (NH4)2[Ce4+(NO3)6] (CAN). They exhibited strong absorption bands around 400 nm together with a broad one around 600-900 nm, the latter of which is also affected by the metal ions. The phenoxyl radical-metal complexes are characterized by resonance Raman, ESI-MS, and ESR spectra, and the metal ion effects on those spectroscopic features are also discussed. Stability and reactivity of the phenoxyl radical-metal complexes are significantly different, depending on the type of metal ions. The disproportionation of the phenoxyl radicals is significantly retarded by the electronic repulsion between the metal cation and a generated organic cation (Ln+), leading to stabilization of the radicals. On the other hand, divalent cations decelerate the rate of hydrogen atom abstraction from 10-methyl-9,10-dihydroacridine (AcrH2) and its 9-substituted derivatives (AcrHR) by the phenoxyl radicals. On the basis of primary kinetic deuterium isotope effects and energetic consideration of the electron-transfer step from AcrH2 to the phenoxyl radical-metal complexes, we propose that the hydrogen atom abstraction by the phenoxyl radical-alkaline earth metal complexes proceeds via electron transfer followed by proton transfer.
Aza-crown ether locked on polyethyleneimine: Solving the contradiction between transfection efficiency and safety during: In vivo gene delivery
Chen, Binggang,Jiang, Sangni,Li, Shengran,Lin, Lin,Liu, Sanrong,Ma, Xiaojing,Tian, Huayu,Wang, Wenliang,Yan, Xinxin,Yu, Xifei
, p. 5552 - 5555 (2020)
We proposed a method using an aza-crown ether derivative to lock a hyperbranched polyethyleneimine, which endows the PEI25k with tumor targeting ability, anti-serum ability and extended circulation in the blood meanwhile retaining the high gene complexation and high transfection efficiency. The method we proposed here simultaneously endows cationic materials with high transfection efficiency and high safety, which greatly pushed the cationic materials to be applied in in vivo gene delivery.
Tridentate phosphine ligands bearing aza-crown ether lariats
Pap, Levente G.,Arulsamy, Navamoney,Hulley, Elliott B.
, p. 385 - 392 (2017/11/30)
Crown ethers are useful macrocycles that act as size-selective binding sites for alkali metals. These frameworks have been incorporated into a number of macromolecular assemblies that use simple cations as reporters and/or activity triggers. Incorporating crown ethers into secondary coordination sphere ligand frameworks for transition metal chemistry will lead to new potential methods for controlling bond formation steps, and routes that couple traditional ligand frameworks with these moieties are highly desirable. Herein we report the syntheses of a family of tridentate phosphine complexes bearing tethered aza-crown ethers (lariats) designed to modularize the variation of aza-crown size, lariat length, and distal phosphine substituents, followed by the synthesis and solid-state structures of Mo(III) complexes bearing cations in the pendent crown ethers.
Synthesis of monoazacrown ethers under phase-transfer catalysis
Luk'yanenko,Basok,Kulygina, E. Yu.,Bogashchenko, T. Yu.,Yakovenko
, p. 1345 - 1352 (2013/02/22)
A procedure has been proposed for the synthesis of monoazacrown ethers by reaction of N-benzyldiethanolamine with oligo(ethylene glycol) bis-p-toluenesulfonates in a two-phase system aromatic hydrocarbon-50% aqueous alkali, followed by removal of the benzyl group by catalytic hydrogenolysis. The maximal yields of N-benzylaza-12-crown-4, -18-crown-6, and -21-crown-7 were achieved by adding 4-10 equiv of LiCl, BaBr2, and CsCl, respectively, to the reaction mixture, which probably indicated template effect. Pleiades Publishing, Ltd., 2012.
Synthesis of N-(bisphosphonomethyl)-aza-15-Crown-5 and N- (bisphosphonomethyl)-aza-18-crown-6 ethers as artificial ion channels: An approach to channel-type molecular structures
Fallouh,Bernier,Virieux,Cristau,Pirat
, p. 219 - 225 (2007/10/03)
We report the synthesis and characterization of 2 new N- (bisphosphonomethyl)-aza-15-crown-5 1a and N-(bisphosphonomethyl)-aza-18-Crown-6 ethers 1b designed to further investigate the supramolecular assemblies based on exocyclic functional groups of crown ethers. Copyright Taylor & Francis LLC.
Thermodynamic study of some pyridinium ion derivatives with 18-crown-6, aza-18-crown-6 and 1,10-diaza-18-crown-6 in acetonitrile
Ganjali,Khoshdan,Hashemi,Seiyed Sajjadi
, p. 1389 - 1398 (2007/10/03)
The complexation between the salts of protonated of pyridine, 2-methyl pyridine, 2,4-dimethyl pyridine and 2,4,6-trimethyl pyridine and macrocyclic ligands 18-crown-6, aza-18-crown-6 and 1,10-diaza-18-crown-6 have been studied conductometrically in acetonitrile at different temperature. Formation constants of the resulting 1:1 complexes were determined by the computer fitting of the molar conductance-mole ratio data. The stability of complexes decrease in the sequence: 1,10-diaza-18-crown-6 > aza-18-crown-6 > 18-crown-6. The enthalpy and entropy of complexation were determined from the temperature dependence of the formation constants. In all cases, the complexes were enthalpy stabilized, but entropy destabilized.
Lipophilic Bis(monoaza crown ether) Derivatives: Synthesis and Cation-Complexing Properties
Sakamoto, Hidefumi,Kimura, Keiichi,Koseki, Yasuaki,Matsuo, Mitsunori,Shono, Toshiyuki
, p. 4974 - 4979 (2007/10/02)
Eleven lipophilic bis(monoaza crown ether) derivatives were synthesized, in which two monoaza crown ethers with 9-, 12-, 15-, or 18-membered rings are linked through the nitrogen atoms by an alkane-, diether-, or diester-type bridge chain bearing a dodecyl group.Sodium and potassium binding with the bis(monoaza crown ether) was determined potentiometrically and compared with those for previous bis(crown ethers) 5 (n = 1 - 3) and corresponding monocyclic analogues 4 and 6 (n = 1 - 3).Marked bis(crown ether) effect was observed only for the alkane-type bis(monoaza-12-crown-4) and bis(monoaza-15-crown-5) derivatives 1 (n = 1,2) on complexing Na+ and K+, respectively.It was suggested that in some of the other bis(monoaza crown ethers) lariat-ether effect works instead.Bis(monoaza-9-crown-3) derivatives 1 and 2 (n = 0) possess very poor cation-complexing ability.Acidity constant values gave some hints about the bis(crown ether) effect.
Na+ Complexation of New Multidentate Polyether Ligands - Rapid Estimation of Complexation Constants by 23Na NMR Spectroscopy
Offermann, Werner,Weber, Edwin
, p. 234 - 245 (2007/10/02)
A new 23Na NMR method for fast and simple estimation of Na+ complex stabilities is reported and applied to various polyether ligands.Synthesis of the new coronands and podands amongst the employed substrates are given.
Synthesis of Monoaza Crown Ethers from N,N-Diamines and Oligoethylene Glycol Di(p-toluenesulfonates) or Corresponding Dichlorides
Maeda, Hirokazu,Furuyoshi, Shigeo,Nakatsuji, Yohji,Okahara, Mitsuo
, p. 212 - 218 (2007/10/02)
Monoaza crown ethers were prepared in satisfactory yields by the one-step reaction between diethanolamine or N,N-diamines and oligoethylene glycol di(p-toluenesulfonates) or corresponding dichlorides in t-butyl alcohol/dioxane in the presence of sodium or potassium t-butoxide.The reaction conditions in the preparation of monoaza 15- and 18-crown ethers were studied.Various monoaza crown ethers having substituents were also prepared and their properties were investigated.
INTRAMOLECULAR CYCLIZATION OF N,N-Di(OLIGOOXYETHYLENE)AMINES: A NEW SYNTHESIS OF MONOAZA CROWN ETHERS
Maeda, Hirokazu,Furuyoshi, Shigeo,Nakatsuji, Yohji,Okahara, Mitsuo
, p. 3359 - 3362 (2007/10/02)
The reaction of N,N-di(oligooxyethylene)amines with arenesulfonyl chloride in the presence of alkali metal hydroxide was investigated.It was found that the monoarenesulfonates of N,N-di(oligooxyethylene)amines were first formed as intermediates, and their subsequent intramolecular cyclization gave N-unsubstituted monoaza crown ethers rather selectively.
