Phenoxide and alkoxide complexes of Mg, Al and Zn, and their use for the ring-opening polymerization of ɛ-caprolactone with initiators of different natures

Minyaev, Mikhail E.; Nifant’ev, Ilya E.; Shlyakhtin, Andrey V.; Ivchenko, Pavel V.

doi:10.1107/s2053229618005090

Cited by 9 publications

(5 citation statements)

References 53 publications

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“…As noted above [67], Mg derivatives of the chelating NNN ligand outperform Al complexes in catalytic activity. In recent years, very simple and synthetically available aryloxy magnesium complexes drawn attention of the researchers due to their high catalytic activity in ROP [89,90,91,92,93,94,95]. In our study of Mg derivatives of 2,6-di- tert -butyl-4-methylphenol (BHT) we first proposed that the binuclear complex 24a (Figure 6) dissociates with a formation of mononuclear species 25a [70] and made DFT modeling of ROP of different cyclic esters using PRIRODA program [96].…”

Section: Coordination Polymerization Of Lactonesmentioning

confidence: 99%

“…As demonstrated in a number of publications, heteroleptic metal alkoxides form stable binuclear complexes [69,94,97,99,140,147,148,149] that are able to catalyze ROP of cyclic esters by both binuclear and mononuclear mechanisms. DFT modeling has been shown to be an effective instrument of choice of the preferable reaction pathway.…”

Section: Coordination Polymerization Of Lactides and Glycolidementioning

confidence: 99%

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Coordination Ring-Opening Polymerization of Cyclic Esters: A Critical Overview of DFT Modeling and Visualization of the Reaction Mechanisms

Nifant’ev

Ivchenko

2019

Molecules

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Ring-opening polymerization (ROP) of cyclic esters (lactones, lactides, cyclic carbonates and phosphates) is an effective tool to synthesize biocompatible and biodegradable polymers. Metal complexes effectively catalyze ROP, a remarkable diversity of the ROP mechanisms prompted the use of density functional theory (DFT) methods for simulation and visualization of the ROP pathways. Optimization of the molecular structures of the key reaction intermediates and transition states has allowed to explain the values of catalytic activities and stereocontrol events. DFT computation data sets might be viewed as a sound basis for the design of novel ROP catalysts and cyclic substrates, for the creation of new types of homo- and copolymers with promising properties. In this review, we summarized the results of DFT modeling of coordination ROP of cyclic esters. The importance to understand the difference between initiation and propagation stages, to consider the possibility of polymer–catalyst coordination, to figure out the key transition states, and other aspects of DFT simulation and visualization of ROP have been also discussed in our review.

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Section: Coordination Polymerization Of Lactonesmentioning

confidence: 99%

Section: Coordination Polymerization Of Lactides and Glycolidementioning

confidence: 99%

Coordination Ring-Opening Polymerization of Cyclic Esters: A Critical Overview of DFT Modeling and Visualization of the Reaction Mechanisms

Nifant’ev

Ivchenko

2019

Molecules

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“…It is known that complexes [Mg(BHT)(OR)(THF) n ] 2 (n = 0, 1; BHT = O-2,6-t Bu 2 -4-MeC 6 H 2 or the anion of butylated hydroxytoluene) are active in ring-opening polymerization (ROP) of cyclic esters (Nifant'ev et al, 2016(Nifant'ev et al, , 2017, whereas Mg(BHT) 2 (THF) 2 is catalytically inactive, but displays relatively high catalytic activity upon activation by a primary alcohol (see, for example, Chen et al, 2012). The ROP of "-caprolactone ("-CL) to poly("-caprolactone) (PCL) can be carried out on the precatalyst Mg(BHT) 2 (THF) 2 activated even by various bulky alcohols (Minyaev et al, 2018). We have tested the obtained diols (I) and (II) as activators of the Mg(BHT) 2 (THF) 2 precatalyst for polymerization of "-CL (Fig.…”

Section: Chemical Contextmentioning

confidence: 99%

(1R,2S,4r)-1,2,4-Triphenylcyclopentane-1,2-diol and (1R,2S,4r)-4-(2-methoxyphenyl)-1,2-diphenylcyclopentane-1,2-diol: application as initiators for ring-opening polymerization of ∊-caprolactone

et al. 2019

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Reductive cyclization of 1,3,5-triphenyl- and 3-(2-methoxyphenyl)-1,5-diphenylpentane-1,5-diones by zinc in acetic acid medium leads to the formation of 1,2,4-triphenylcyclopentane-1,2-diol [1,2,4-Ph3C5H5-1,2-(OH)2, C23H22O2, (I)] and 4-(2-methoxyphenyl)-1,2-diphenylcyclopentane-1,2-diol [4-(2-MeOC6H4)-1,2-Ph2C5H5-1,2-(OH)2, C24H24O3, (II)]. Their single crystals have been obtained by crystallization from a THF/hexane solvent mixture. Diols (I) and (II) crystallize in orthorhombic (Pbca) and triclinic (P\overline{1}) space groups, respectively, at 150 K. Their asymmetric units comprise one [in the case of (I)] and three [in the case of (II)] crystallographically independent molecules of the achiral (1R,2S,4r)-diol isomer. Each hydroxyl group is involved in one intramolecular and one intermolecular O—H...O hydrogen bond, forming one-dimensional chains. Compounds (I) and (II) have been used successfully as precatalyst activators for the ring-opening polymerization of ∊-caprolactone.

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“…In the recent years, the promising catalytic properties in ROP of different cyclic esters were demonstrated for the complexes of ‘biometals’ (Na, Mg, Ca, Zn and Al) with bulky phenols such as 2,6-di- tert -butyl-4-methylphenol (BHT-H) [ 81 , 93 , 94 , 95 , 96 , 97 , 98 , 99 ]. These synthetically available complexes represent a suitable model for the understanding fundamentals of co-ROP [ 47 ].…”

Section: Introductionmentioning

confidence: 99%

Comparative Experimental and Theoretical Study of Mg, Al and Zn Aryloxy Complexes in Copolymerization of Cyclic Esters: The Role of the Metal Coordination in Formation of Random Copolymers

et al. 2020

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Homogeneity of copolymers is a general problem of catalytic coordination polymerization. In ring-opening polymerization of cyclic esters, the rational design of the catalyst is generally applied to solve this problem by the equalization of the reactivities of comonomers—however, it often leads to a reduction of catalytic activity. In the present paper, we studied the catalytic behavior of BnOH-activated complexes (ВНТ)Mg(THF)2nBu (1), (ВНТ)2AlMe (2) and [(ВНТ)ZnEt]2 (3), based on 2,6-di-tert-butyl-4-methylphenol (BHT-H) in homo- and copolymerization of L-lactide (lLA) and ε-caprolactone (εCL). Even at 1:5 lLA/εCL ratio Mg complex 1 catalyzed homopolymerization of lLA without involving εCL to the formation of the polymer backbone. On the contrary, Zn complex 3 efficiently catalyzed random lLA/εCL copolymerization; the presence of mono-lactate subunits in the copolymer chain clearly pointed to the transesterification mechanism of copolymer formation. Both epimerization and transesterification side processes were analyzed using the density functional theory (DFT) modeling that confirmed the qualitative difference in catalytic behavior of 1 and 3: Mg and Zn complexes demonstrated different types of preferable coordination on the PLA chain (k2 and k3, respectively) with the result that complex 3 catalyzed controlled εCL ROP/PLA transesterification, providing the formation of lLA/εCL copolymers that contain mono-lactate fragments separated by short oligo(εCL) chains. The best results in the synthesis of random lLA/εCL copolymers were obtained during experiments on transesterification of commercially available PLLA, the applicability of 3/BnOH catalyst in the synthesis of random copolymers of εCL with methyl glycolide, ethyl ethylene phosphonate and ethyl ethylene phosphate was also demonstrated.

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Phenoxide and alkoxide complexes of Mg, Al and Zn, and their use for the ring-opening polymerization of ɛ-caprolactone with initiators of different natures

Cited by 9 publications

References 53 publications

Coordination Ring-Opening Polymerization of Cyclic Esters: A Critical Overview of DFT Modeling and Visualization of the Reaction Mechanisms

Coordination Ring-Opening Polymerization of Cyclic Esters: A Critical Overview of DFT Modeling and Visualization of the Reaction Mechanisms

(1R,2S,4r)-1,2,4-Triphenylcyclopentane-1,2-diol and (1R,2S,4r)-4-(2-methoxyphenyl)-1,2-diphenylcyclopentane-1,2-diol: application as initiators for ring-opening polymerization of ∊-caprolactone

Comparative Experimental and Theoretical Study of Mg, Al and Zn Aryloxy Complexes in Copolymerization of Cyclic Esters: The Role of the Metal Coordination in Formation of Random Copolymers

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