Synthesis, structures, and catalytic efficiency in ring opening polymerization of rac-lactide with tridentate vs. bidentate cobalt(ii), zinc(ii), and cadmium(ii) complexes containing N-substituted N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amine ligands

Abstract

Co(ii), Zn(ii), and Cd(ii) complexes supported by bis-pyrazolyl ligands were applied to the ring-opening polymerization of rac-lactide to produce heterotactic polylactides (PLAs) with superior heterotactic bias i.e. Pr up to 0.94 at −25 °C.

Synthesis and Characterization of Zinc(II), Cadmium(II), and Palladium(II) Complexes with the Thiophene-Derived Schiff Base Ligand

“…However, further increase in the [ rac -LA] 0 /[catalyst] ratio up to 700:1 resulted in only 31% conversion under identical experimental protocols, and a decrease in the molecular weight of resultant PLA was also observed with this decrease in conversion (Figure ). Depending on the metal center variation, [L TH ZnCl 2 ]/LiO i Pr resulted in a high heterotactic enchainment ( P r = 0.74 at 0 °C) compared to its Cd­(II) and Pd­(II) complexes, consistent with the findings of previous studies. , Decrease in polymerization temperature did not show any significant enhancement of the heterotactic bias, particularly for the Cd­(II)-based initiator. The geometry of the M­(II) complex might have steered the hetereotacticity of PLA in the studied complexes.…”

“…This might be due to the rigidity of the 4-(quinolin-2-ylmethyl)­morpholine ligand framework compared to L TH . As it was shown earlier, ,− the rac -LA ROP proceeds through a monomer-activated mechanism initiated by diispropoxide-based Zn­(II) species. It was shown that for rac -LA polymerization, the studied catalytic system outperforms the Zn­(II) complexes of tridentate Schiff bases with morpholine/piperidine/pyridine/quinoline functionalities for rac -LA polymerization with better conversion and polymerization control of PLA production.…”

Pyridine‐derived Schiff base copper (II), zinc (II), and cadmium (II) complexes: Synthesis, structural properties, biological evaluation, and docking studies

“…The N imine -M-N amine and N pyridine -M-N amine bond angles signifies trigonal bipyramidal and square pyramidal geometries for these complexes. 8,[65][66][67]69 The Cl terminal -M-Cl terminal bond angles in [DEP(Cu) Cl 2 ] and [DEP(Zn)Cl 2 ] were 103.12(4) and 117.87 (19) , respectively, whereas the…”

Highly active cobalt(II) and copper(II) complexes supported by aminomethylquinoline mediating stereoselective ring‐opening polymerization of rac‐lactide

“…10 Recent advancements in developing efficient stereoselective catalysts are based on late transition metal initiators with different ancillary ligands toward the ROP of rac-LAs. [11][12][13][14][15][16] We recently established the role of the initiating groups, namely, LiMe, LiO i Pr, and LiCl, based on their basicity, for Zn(II) complexes in a controlled ROP of rac-LA. 17 In our previous studies on LA polymerization, we focused on the LiMe system.…”

“…17 In our previous studies on LA polymerization, we focused on the LiMe system. 11,12,16 Here, we discuss the impact of the initiating groups, LiMe and LiO i Pr on the ROP properties of Co(II) and Cu(II) complexes containing an Jaegyeong Lee and Saira Nayab contributed equally to this article. aminomethylquinoline (L) ligand.…”