19028-72-9Relevant academic research and scientific papers
Manganese(ii) Schiff-base-mediated reversible deactivation controlled radical polymerization of vinyl acetate
Hashimoto, Patricia K.,Oliveira, Larissa F.,Riga-Rocha, Beatriz A.,MacHado, Antonio E. H.,Santana, Vinicius T.,Nascimento, Otaciro R.,Carvalho-Jr, Valdemiro P.,Goi, Beatriz E.
, p. 10109 - 10117 (2021)
A series of new manganese(ii) complexes were prepared with three bidentate Schiff-base ligands derived by condensation of salicylaldehyde and different cycloalkylamines (cycloalkyl = cyclopentyl, cyclohexyl, and cycloheptyl): [Mn(CyPen-Salicyl)2] (1), [Mn(CyHex-Salicyl)2] (2), and [Mn(CyHep-Salicyl)2] (3). The complexes 1-3 were characterized by FTIR, UV-vis and EPR spectroscopy, elemental analysis, cyclic voltammetry, and computational methods. The manganese(ii) complexes (1-3) were used as controlling agents for the polymerization of vinyl acetate (VAc) initiated by AIBN according to an organometallic-mediated radical polymerization (OMRP) mechanism. The VAc polymerization mediated by the Mn complexes suggests that the control level can be slightly tuned through substitution of the cycloalkyl group on the Schiff-base ligand. Kinetics studies and computational investigations support an RT mechanism and a tailorable Mn complex reactivity mainly altered by steric factors of the Schiff-base ligands. The calculated thermodynamic parameters agree with the mediating ability of these complexes, since the degree of polymerization control decreases with increasing steric hindrance of the Schiff-base ligands, as well as with increasing ΔG values for the formation of dormant species.
The structures of some ortho-hydroxy Schiff base ligands
Fernández-G,Del Rio-Portilla,Quiroz-García,Toscano,Salcedo
, p. 197 - 207 (2001)
Nine ortho-hydroxy Schiff base ligands, (1)-(9), were synthesized and characterized by chemical analysis, mass spectrometry, 1H and 13C NMR spectroscopy. The crystal and molecular structures of compounds (1), (3), (5), (7), (8) and (
Catalyst-free direct ring-opening of cyclic aldimines with aliphatic primary amines to construct o-hydroxy schiff bases
Cao, Zubin,Ding, Qiuyue,Han, Dongyun,Li, Feng,Wang, Jingjing,Wu, Ziyan,Zhai, Hanhui
supporting information, (2022/01/28)
We firstly describe a catalyst-free direct ring-opening of cyclic aldimines with abundant aliphatic primary amines to construct o-hydroxy schiff bases under mild reaction conditions. The corresponding products were generated in good to excellent yields (80–99%). In addition, a gram-scale reaction and further application of the reaction strategy were performed.
Modulation of imine chemistry with intramolecular hydrogen bonding: Effects from ortho-OH to NH
Chen, Hang,Feng, Zelin,Jia, Shuaipeng,You, Lei
supporting information, (2020/03/24)
Salicylaldehyde derivatives and their imines are important building blocks in organic and supramolecular chemistry. In an effort to expand structural diversity in the current work we changed ortho-OH in salicylaldehyde to NH of amide/sulfonamide and investigated the effect of resulting intramolecular hydrogen bonds on imine dynamic covalent chemistry (DCC). A suite of ortho-aminobenzaldehydes were readily synthesized, and X-ray and NMR data validated the existence of NH?O intramolecular hydrogen bonds. The formation and exchange of imines were then studied in acetonitrile, and the acidity of OH/NH significantly influenced the thermodynamics and kinetics of imine reactions. Furthermore, the role of OH/NH?N hydrogen bonds on imines was elucidated by the shift of aldehyde exchange equilibrium. Finally, the formation of imines was achieved in aqueous solutions. The mechanistic insights could pave the way for future applications in assembly and labelling.
Hydrogen-Bond Catalysis of Imine Exchange in Dynamic Covalent Systems
Schaufelberger, Fredrik,Seigel, Karolina,Ramstr?m, Olof
supporting information, p. 15581 - 15588 (2020/10/02)
The reversibility of imine bonds has been exploited to great effect in the field of dynamic covalent chemistry, with applications such as preparation of functional systems, dynamic materials, molecular machines, and covalent organic frameworks. However, acid catalysis is commonly needed for efficient equilibration of imine mixtures. Herein, it is demonstrated that hydrogen bond donors such as thioureas and squaramides can catalyze the equilibration of dynamic imine systems under unprecedentedly mild conditions. Catalysis occurs in a range of solvents and in the presence of many sensitive additives, showing moderate to good rate accelerations for both imine metathesis and transimination with amines, hydrazines, and hydroxylamines. Furthermore, the catalyst proved simple to immobilize, introducing both reusability and extended control of the equilibration process.
Subtle variation of stereo-electronic effects in rhodium(I) carbonyl Schiff base complexes and their iodomethane oxidative addition kinetics
Mokolokolo, Pennie P.,Brink, Alice,Roodt, Andreas,Schutte-Smith, Marietjie
, p. 2740 - 2762 (2020/09/01)
Rhodium(I) carbonyl complexes of the form [RhI(N,O-ScBa)(CO)(PR3)] (R = Ph or Cy), with N,O-ScBaH a mono anionic bidentate Schiff base ligand, 2-(cyclopentyliminomethyl)-5-methylphenol (5-Me-Sal-CyPH), and bearing different phosphine
Molybdenum-Catalyzed Dehydrogenative Synthesis of Imines from Alcohols and Amines
Azizi, Kobra,Madsen, Robert
, p. 3703 - 3708 (2018/07/31)
A molybdenum N-heterocyclic carbene catalyst has been developed for the synthesis of imines from primary alcohols and amines with the liberation of dihydrogen. The catalyst is generated in situ from molybdenum hexacarbonyl, 1,3-dicyclohexylimidazolium chloride and potassium tert-butoxide and is further stabilized by the phosphine ligand dppe. Imines are formed in moderate to good isolated yields and a variety of alcohols and amines can be employed in the reaction including anilines. The transformation constitutes the first example of a homogeneous molybdenum-catalyzed acceptorless dehydrogenative coupling with alcohols and is believed to proceed by formation of a cis-coordinated molybdenum bis-N-heterocyclic carbene complex, which performs an oxidative addition to the alcohol, β-hydride elimination and reductive elimination of dihydrogen.
Dinuclear iminophenoxide copper complexes in rac-lactide polymerisation
Daneshmand, Pargol,Pinon, Leena,Schaper, Frank
, p. 10147 - 10161 (2018/08/09)
Dinuclear bis(R′-(R′′-iminomethyl)phenoxide) copper complexes L2Cu2(μ-OR)2 were prepared from the reaction of copper methoxide with ROH and LH (ROH = dimethylaminoethanol or pyridylmethanol, R′ = H, 4,6-tBu, 1,3-Cl, R′′ = benzyl, cyclohexyl, diphenylmethyl and 2,6-dimethylphenyl). Preparation was complicated by formation of homoleptic L2Cu and only 9 of the 24 possible combinations could be prepared. All complexes were characterized by single crystal X-ray diffraction studies and crystallized as dinuclear penta-coordinated complexes. Homoleptic complexes L2Cu were inactive in lactide polymerization at room temperature. Most heteroleptic complexes showed modest to good activities with full conversion in less than 6 h at room temperature. Complexes with R′ = H showed poor molecular weight control, complexes with R′ = Cl were inactive in polymerization. In pyridylmethoxide-containing complexes, only one alkoxide initiated chain growth. All complexes produced atactic polymer.
Organometallic-mediated radical polymerization using well-defined Schiff base cobalt(II) complexes
Silva, Yan F.,Riga, Beatriz A.,Deflon, Victor M.,Souza, Jhonathan R.,Silva, Leonardo H. F.,Machado, Antonio E. H.,Maia, Pedro Ivo S.,Valdemiro P, Carvalho-Jr,Goi, Beatriz E.
, p. 3776 - 3789 (2018/12/04)
A series of new cobalt(II) complexes of Schiff base derived from salicylaldehyde and different cycloalkylamines (cycloalkyl = cyclopentyl-1a, cyclohexyl-1b, and cycloheptyl-1c) was synthesized: [Co(CyPen-Salicyl)2] (2a), [Co(CyHex-Salicyl)
Ruthenium(II) complexes of Schiff base derived from cycloalkylamines as pre-catalysts for ROMP of norbornene and ATRP of methyl methacrylate
Afonso, Maria Beatriz A.,Cruz, Thais R.,Silva, Yan F.,Pereira, Jo?o Clécio A.,Machado, Antonio E.H.,Goi, Beatriz E.,Lima-Neto, Benedito S.,Carvalho-Jr, Valdemiro P.
, p. 225 - 234 (2017/10/10)
Ruthenium(II) complexes of Schiff base derived from cycloalkylamines (cycloalkyl = cyclopentyl (1a), cyclohexyl (1b), cycloheptyl (1c), and cyclooctyl) (1d) were synthesized: [RuCl(CyPen-Salen)(PPh3)2] (2a), [RuCl(CyHex-Salen)(PPhsu
