83816-59-5Relevant articles and documents
Synthesis of new chiral Mn(iii)-salen complexes as recoverable and reusable homogeneous catalysts for the asymmetric epoxidation of styrenes and chromenes
Chaudhary, Pooja,Damodaran, Krishna K.,Singh, Surendra,Yadav, Geeta Devi
, p. 1308 - 1318 (2022/02/07)
New chiral Mn(iii)-salen complexes 1a-e and 2a-e were synthesized from the reaction of C2-symmetric chiral salen ligands and Mn(CH3COO)2·4H2O under an inert atmosphere followed by aerobic oxidation. These complexes were obtained in 91-96% yields and characterized by HRMS, FT-IR, UV-visible spectroscopy, TGA, and elemental analysis. The chiral Mn(iii)-salen complexes 1a-e and 2a-e were evaluated in the asymmetric epoxidation of styrene using NaOCl as an oxidant in ethyl acetate as a green solvent. The chiral Mn(iii)-salen complexes 1b and 2b (2 mol%) catalyzed the asymmetric epoxidation of substituted styrenes and chromenes to afford the corresponding epoxides in 95-98% yields with 29-88% ee's. The catalysts 1b and 2b were recovered and reused for up to 2 and 3 runs, respectively, in the asymmetric epoxidation of styrene, and the yield of styrene oxide gradually decreased but the ee was consistent.
Di- and trinuclear iron/titanium and iron/zirconium complexes with heterocyclic ligands as catalysts for ethylene polymerization
G?rl, Christian,Betthausen, Eva,Alt, Helmut G.
, p. 37 - 51 (2016/08/23)
The properties of polyolefin resins depend very much on their molecular weights, the amount of side chain branchings and molecular weight distributions. One way to obtain such tailored products in only one reaction step consists in the application of dissymmetric multi nuclear catalysts with different active sites. Since every active site is producing its own polymer, a “molecular blending” is the result. In order to reach this goal, a variety of mono, di- and trinuclear complexes of iron, titanium and zirconium, containing 2,6-bis(aryliminoethyl)pyridine and phenoxyimine building blocks have been synthesized and characterized. The reaction of iodo functionalized 2,6-bis(arylimino-ethyl)pyridine derivatives with alkyne functionalized phenoxyimine compounds via Sonogashira cross-coupling reactions results in ligand precursors that can provide coordination sites for two different metals. Trinuclear complexes with the combinations Ti/Fe and Zr/Fe, each molecule containing two iron atoms in two 2,6-bis(aryliminoethyl)pyridine units, gave the best ethylene polymerization results. Due to fast ligand exchange reactions, dinuclear iron/titanium complexes could not be isolated from reactions of mono(phenoxyimine) titanium complexes and the coupled bis(chelate) ligand precursor. Since the metal centers show their best performances at different polymerization temperatures, the compositions (and, therefore, the molecular weight distributions) of the desired polyethylenes may be adjusted by a simple change of the reaction temperature.
(R,R)-salen/salan-based polymer fluorescence sensors for Zn2+ detection
Song, Fengyan,Ma, Xiao,Hou, Jiali,Huang, Xiaobo,Cheng, Yixiang,Zhu, Chengjian
, p. 6029 - 6036 (2012/04/10)
(R,R)-salen-based polymer fluorescence sensor P-1 could be synthesized by the polymerization of 5,5′-(isoquinoline-5,8-diylbis(ethyne-2,1-diyl))- bis(3-tert-butyl-2-hydroxybenzaldehyde) (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via nucleophilic addition-elimination reaction, and (R,R)-salan-based polymer sensor P-2 could be obtained by the reduction reaction of P-1 with NaBH4. The fluorescence response behaviors of two chiral polymers P-1 and P-2 on Zn2+ were investigated by fluorescence spectra. The fluorescence intensities of P-1 and P-2 can exhibit gradual enhancement upon addition of Zn2+. Compared with other cations, such as Na +, K+, Mg2+, Ca2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Cd 2+, Cr3+ and Pb2+, Zn2+ can lead to the pronounced fluorescence enhancement as high as 22.8-fold for P-1 and 3.75-fold for P-2, respectively. The results show that P-1 and P-2 incorporating (R,R)-salen/salan moieties as receptors in the polymer main chain backbone can exhibit high sensitivity and selectivity for Zn2+ detection.