Lee Jaegyeong, Yoon Minyoung, Lee Hyosun, Nayab Saira
Department of Chemistry, Green-Nano Materials Research Center, Kyungpook National University 80 Daehakro, Bukgu Daegu 41566 Republic of Korea
Department of Chemistry, Shaheed Benazir Bhutto University Sheringal Dir (U) Khyber Pakhtunkhwa Islamic Republic of Pakistan
RSC Adv. 2020 Apr 23;10(27):16209-16220. doi: 10.1039/d0ra00805b. eCollection 2020 Apr 21.
Iminomethylpyridine based copper(ii) complexes [LCuCl] (L = L, L-L) and [LCu(μ-Cl)Cl] have been synthesized and characterized. [LCuCl] and [LCuCl] were identified to possess distorted square pyramidal geometries obtained ,'-bidentate coordination, whereas [LCuCl] showed ,',''-coordination of the corresponding ligand (L). [LCu(μ-Cl)Cl] was found to be dimeric with a distorted square pyramidal geometry around the Cu(ii) center. The catalytic properties of dimethyl derivatives, generated , towards the ring opening polymerization (ROP) of -LA were investigated. All the complexes efficiently polymerized -LA and yielded heterotactic poly(lactide) (PLA) ( up to 0.88 at -25 °C). Further, these complexes could effectively polymerize methyl methacrylate (MMA) at 60 °C in the presence of modified methylaluminoxane (MMAO), to furnish syndio-enriched PMMA. The catalytic efficacies of synthesized complexes can be correlated to the suitable complexity of the substituents attached to the ligand architecture. Thus, both the steric and electronic properties as well as the orientation of the various substituents relative to the plane of the pyridyl moiety and metal center play an influential role in steering catalytic activities, whereas the selectivities remain unaffected.
基于亚氨基甲基吡啶的铜(II)配合物[LCuCl](L = L,L-L)和[LCu(μ-Cl)Cl]已被合成并表征。[LCuCl]和[LCuCl]被确定具有通过,'-双齿配位获得的扭曲四方锥几何结构,而[LCuCl]显示出相应配体(L)的,'',''-配位。发现[LCu(μ-Cl)Cl]是二聚体,在Cu(II)中心周围具有扭曲的四方锥几何结构。研究了由,-LA产生的二甲基衍生物对-己内酯开环聚合(ROP)的催化性能。所有配合物均能有效地使-LA聚合,并产生全同立构聚丙交酯(PLA)(在-25°C下高达0.88)。此外,这些配合物在改性甲基铝氧烷(MMAO)存在下,于60°C能有效地使甲基丙烯酸甲酯(MMA)聚合,得到富含间同立构的聚甲基丙烯酸甲酯(PMMA)。合成配合物的催化效率与连接到配体结构上的取代基的适当复杂性相关。因此,空间和电子性质以及各种取代基相对于吡啶基部分和金属中心平面的取向在控制催化活性方面起着重要作用,而选择性不受影响。