1204302-25-9Relevant academic research and scientific papers
Coordinating effect in ring-opening polymerization of ε-caprolactone using aluminum complexes bearing bisphenolate as catalysts
Chen, Hsing-Yin,Lee, Ying-Hsien,Chiang, Michael Y.,Lu, Wei-Yi,Tseng, Hsi-Ching,Tsai, Hsin-Yi,Chen, Yu-Hsieh,Lai, Yi-Chun,Chen, Hsuan-Ying
, p. 82018 - 82026 (2015)
A series of Al complexes bearing diphenolate ligands was synthesized and their application for the ring-opening polymerization of ε-caprolactone was studied. Positional variation of the substituent on the aryl ring of the RCH(4,6-di-t-butylphenol)2 ligand was shown to have a considerable influence on the catalysis result. Complexes with a ortho-substituent showed greater catalytic activity than those with a para-substituent. Substitutions of an aryl moiety by H or methyl groups resulted in the catalytic activity falling between that of the ortho-substitution Al complexes and that of the para ones. Our results demonstrate that the coordinated functional group in the ortho-position of the phenyl ring could increase the catalytic activity. Moreover, X-rays of the structure and DFT analysis revealed that the coordinated functional group in the ortho-position could bridge two Al centers resulting in the transformation of a dinuclear Al complex with bridging benzyl alkoxide into a complex with terminal benzyl alkoxide, further promoting the efficacy of the initiator.
Heteroleptic lanthanide amide complexes bearing carbon-bridged bis(phenolate) ligands: Synthesis, structure and their application in the polymerization of ε-caprolactone
Zhou, Yan-Xu,Zhao, Jing,Peng, Ling,Wang, Yu-Long,Tao, Xian,Shen, Ying-Zhong
, p. 22269 - 22276 (2016)
A convenient method for the synthesis of anionic lanthanide amide complexes bearing carbon-bridged bis(phenolate) ligands H2L [L = (o-CH3)PhCH(C6H2-3-tBu-5-R-2-O)2; R = Me, L = L1 and R = tBu, L = L2] is described. The bis(phenolato)lanthanide complexes LLnN(SiMe3) [L = L1, Ln = La (1), Ln = Gd (2) and L = L2, Ln = La (3), Ln = Gd (4)] were synthesized in nearly quantitative yields by the reaction of Ln[N(SiMe3)2]3 (Ln = La or Gd) with H2L in a 1 : 1 molar ratio in THF at 60 °C. The bis(phenolato)lanthanide pyrazolato complexes LLnPzMe2(THF)3 [L = L1, Ln = La (5), Ln = Gd (6) and L = L2, Ln = La (7), Ln = Gd (8)] were obtained in high yields by further reacting the obtained LLnN(SiMe3) with another 1 equiv. of 3,5-dimethylpyrazole (Me2PzH). Meanwhile, the complexes LLnPzMe2 can also be synthesized by the direct reaction of Ln[N(SiMe3)2]3 with H2L and Me2PzH in 1 : 1 : 1 molar ratio in situ in THF. Complexes 5-8 have been characterized by X-ray crystal structural analysis. The central lanthanide metal atom is seven-coordinated by one bis(phenolate) ligand, one pyrazole ligand and three THF molecules in a distorted pentagonal bipyramid. The catalytic activity of compounds 1-8 in the ring-opening polymerization of ε-caprolactone was studied. The catalytic mechanism was studied and discussed as well.
Synthesis and structural studies of heterobimetallic alkoxide complexes supported by bis(phenolate) ligands: Efficient catalysts for ring-opening polymerization of l-lactide
Chen, Hsuan-Ying,Liu, Mei-Yu,Sutar, Alekha Kumar,Lin, Chu-Chieh
experimental part, p. 665 - 674 (2010/03/25)
A series of heteroblmetallic titanium(IV) complexes [LTi(O′Pr)(μ- O′Pr)2Li(THF)2], [LTi(O′Pr)(μ-O′Pr) 2Na(THF)2], [LTi(μ-O′Pr)2Zn(O′ Pr)2], and [LTi(μ-O′Pr)2Mg(O′Pr) 2] (where L = bidentate bisphenol ligands) have been synthesized and characterized including a structural determination of [L1Ti(μ 2-O′Pr)2(O′Pr)Li(THF)2] (1a). These complexes were investigated for their utility in the ring-opening polymerization (ROP) of L-lactide (LA). Polymerization activities have been shown to correlate with the electronic properties of the substituent within the bisphenol ligand. In contrast to monometallic titanium Initiator 1e, all the heterobimetallic titanium initiators (Ti-Li, Ti-Na, Ti-Zn, and Ti-Mg) show enhanced catalytic activity toward ring-opening polymerization (ROP) of L-LA. In addition, the use of electron-donating methoxy or methylphenylsulfonyl functional ligands reveals the highest activity. The bisphenol bimetallic complexes give rise to controlled ring-opening polymerization, as shown by the linear relationship between the percentage conversion and the number-average molecular weight. The polymerization kinetics using 2c as an initiator were also studied, and the experimental results indicate that the reaction rate is first-order with respect to both monomer and catalyst concentration with a polymerization rate constant, k = 81.64 M-1 min-1.
