scholarly journals DFT Visualization and Experimental Evidence of BHT-Mg-Catalyzed Copolymerization of Lactides, Lactones and Ethylene Phosphates

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1641 ◽  
Author(s):  
Ilya Nifant’ev ◽  
Andrey Shlyakhtin ◽  
Maxim Kosarev ◽  
Dmitry Gavrilov ◽  
Stanislav Karchevsky ◽  
...  
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Point Of View ◽  
Basis Set ◽  
Random Copolymers ◽  
Key Factors ◽  
Functional Theory ◽  
Cyclic Esters ◽  
Dft Modeling ◽  
Derivatives Of

Catalytic ring-opening polymerization (ROP) of cyclic esters (lactides, lactones) and cyclic ethylene phosphates is an effective way to process materials with regulated hydrophilicity and controlled biodegradability. Random copolymers of cyclic monomers of different chemical nature are highly attractive due to their high variability of characteristics. Aryloxy-alkoxy complexes of non-toxic metals such as derivatives of 2,6-di-tert-butyl-4-methylphenoxy magnesium (BHT-Mg) complexes are effective coordination catalysts for homopolymerization of all types of traditional ROP monomers. In the present paper, we report the results of density functional theory (DFT) modeling of BHT-Mg-catalyzed copolymerization for lactone/lactide, lactone/ethylene phosphate and lactide/ethylene phosphate mixtures. ε-Caprolactone (ε-CL), l-lactide (l-LA) and methyl ethylene phosphate (MeOEP) were used as examples of monomers in DFT simulations by the Gaussian-09 program package with the B3PW91/DGTZVP basis set. Both binuclear and mononuclear reaction mechanistic concepts have been applied for the calculations of the reaction profiles. The results of calculations predict the possibility of the formation of random copolymers based on l-LA/MeOEP, and substantial hindrance of copolymerization for ε-CL/l-LA and ε-CL/MeOEP pairs. From the mechanistic point of view, the formation of highly stable five-membered chelate by the products of l-LA ring-opening and high donor properties of phosphates are the key factors that rule the reactions. The results of DFT modeling have been confirmed by copolymerization experiments.

scholarly journals 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

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2273
Author(s):  
Ilya Nifant’ev ◽  
Pavel Komarov ◽  
Valeriya Ovchinnikova ◽  
Artem Kiselev ◽  
Mikhail Minyaev ◽  
...  
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Qualitative Difference ◽  
Random Copolymers ◽  
Coordination Polymerization ◽  
Polymer Backbone ◽  
Catalytic Behavior ◽  
Cyclic Esters ◽  
Dft Modeling ◽  
The Density Functional Theory

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 (BHT)Mg(THF)2nBu (1), (BHT)2AlMe (2) and [(BHT)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.

scholarly journals DFT Modeling of Organocatalytic Ring-Opening Polymerization of Cyclic Esters: A Crucial Role of Proton Exchange and Hydrogen Bonding

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2078 ◽  
Author(s):  
Ilya Nifant’ev ◽  
Pavel Ivchenko
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Comparative Modeling ◽  
Ring Opening Polymerization ◽  
Proton Exchange ◽  
Dft Methods ◽  
Experimental Proof ◽  
Cyclic Esters ◽  
Dft Modeling

Organocatalysis is highly efficient in the ring-opening polymerization (ROP) of cyclic esters. A variety of initiators broaden the areas of organocatalysis in polymerization of different monomers, such as lactones, cyclic carbonates, lactides or gycolides, ethylene phosphates and phosphonates, and others. The mechanisms of organocatalytic ROP are at least as diverse as the mechanisms of coordination ROP; the study of these mechanisms is critical in ensuring the polymer compositions and architectures. The use of density functional theory (DFT) methods for comparative modeling and visualization of organocatalytic ROP pathways, in line with experimental proof of the structures of the reaction intermediates, make it possible to establish these mechanisms. In the present review, which continues and complements our recent manuscript that focused on DFT modeling of coordination ROP, we summarized the results of DFT modeling of organocatalytic ROP of cyclic esters and some related organocatalytic processes, such as polyester transesterification.

scholarly journals Protonated heterocyclic derivatives of cyclopropane and cyclopropanone: classical species, alternate sites, and ring fragmentation

2015 ◽  
Vol 93 (7) ◽  
pp. 708-714 ◽  
Author(s):  
Margarida S. Miranda ◽  
Darío J.R. Duarte ◽  
Joaquim C.G. Esteves da Silva ◽  
Joel F. Liebman
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Proton Affinities ◽  
Functional Theory ◽  
Heterocyclic Derivatives ◽  
Gas Phase Basicities ◽  
Derivatives Of

A computational study has been performed for protonated oxygen- or nitrogen-containing heterocyclic derivatives of cyclopropane and cyclopropanone. We have searched for the most stable conformations of the protonated species using density functional theory with the B3LYP functional and the 6-31G(2df,p) basis set. More accurate enthalpy values were obtained from G4 calculations. Proton affinities and gas-phase basicities were accordingly derived.

scholarly journals Mechanistic Insights of BHT-Mg-Catalyzed Ethylene Phosphate’s Coordination Ring-Opening Polymerization: DFT Modeling and Experimental Data

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1105 ◽  
Author(s):  
Ilya Nifant’ev ◽  
Andrey Shlyakhtin ◽  
Maxim Kosarev ◽  
Stanislav Karchevsky ◽  
Pavel Ivchenko
Keyword(s):  
Ring Opening ◽  
Activation Barrier ◽  
Ring Opening Polymerization ◽  
High Rate ◽  
Basis Set ◽  
Cyclic Esters ◽  
Dft Modeling ◽  
Binuclear Species ◽  
Poly Ethylene ◽  
First Time

Poly(ethylene phosphates) are promising polymers for use in biomedical applications. Catalytic ring-opening polymerization (ROP) of cyclic ethylene phosphate monomers (CEPMs) is the most effective approach for obtaining these polymers. The mechanism of coordination ROP of CEPMs remains unclear. We report, for the first time, the results of DFT modeling of CEPM ROP. In these calculations by Gaussian-09 program package with the B3PW91/DGTZVP basis set, we explored methyl ethylene phosphate (MeOEP) ROP catalyzed by dimeric and monomeric catalytic species derived from heteroleptic complex [(BHT)Mg(μ-OBn)(THF)]2 (Mg1, BHT = 2,6-di-tert-butyl-4-methylphenolate). Analysis of the reaction profiles for the binuclear and mononuclear reaction mechanisms allowed us to conclude that the ROP of MeOEP is preferentially catalyzed by mononuclear Mg complexes. This estimation was confirmed by comparative polymerization experiments using MeOEP and traditional monomers ε-caprolactone (εCL), racemic lactide (rac-LA), and l-lactide (l-LA) initiated by Mg1. ROP of MeOEP proceeds at an extremely high rate due to the substantially lower activation barrier calculated for mononuclear mechanism in comparison with that of cyclic esters that polymerize without the dissociation of BHT-Mg binuclear species. We also demonstrated the use of MeOEP as a "monomerization" agent in the synthesis of MeOEP-lactide block copolymers. Comparison of the multiple acceleration of l-LA ROP after MeOEP prepolymerization and formation of atactic PLA blocks in rac-LA polymerization with the heterotactic PLA formation during Mg1-catalyzed homopolymerization also confirmed the mononuclear nature of the polyphosphate-containing catalytic particles.

Structural, Electronic and Nonlinear Optical Properties of Novel Derivatives of 9,12-Diiodo-1,2-dicarba-closo-dodecaborane: Density Functional Theory Approach

2018 ◽  
Vol 73 (11) ◽  
pp. 1037-1045 ◽  
Author(s):  
Aijaz Rasool Chaudhry ◽  
Shabbir Muhammad ◽  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Bakhtiar Ul Haq ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Molecular Orbitals ◽  
Basis Set ◽  
Theory Approach ◽  
Dft Methods ◽  
Functional Theory ◽  
Nlo Properties ◽  
Derivatives Of

AbstractUsing density functional theory (DFT) methods, we shed light on the structural, optical, electronic, and nonlinear optical (NLO) properties of three derivatives of 9,12-diiodo-1,2-dicarba-closo-dodecaborane(12) (C2H10B10I2). The DFT and time-dependent DFT methods are considered very precise and practical to optimize the ground and excited state geometries, respectively. A vibrant intramolecular charge transfer from highest occupied molecular orbitals (HOMOs) to the lowest unoccupied molecular orbitals (LUMOs) was observed in all compounds. The geometrical parameters of the experimental crystal structure, i.e. bond lengths/angles, have been successfully reproduced. The HOMO and LUMO energies, as well as their energy gaps (Eg), were also calculated and compared with each other for all derivatives. The effect of attached groups on electronic, optical, and NLO properties along with detailed structure-property relationship was discussed. For NLO response, the CAM-B3LYP functional along with relatively larger basis set 6-31+G** (for hydrogen, carbon, boron, and oxygen atoms) and LANL2DZ (for iodine atoms) have been used to optimize the compounds at ground states. The calculation of second-order NLO polarizabilities (βtot) shows that compounds 2 and 3 possess the βtot amplitudes of 3029 and 4069 a.u., respectively, with CAM-B3LYP method that are reasonably larger than similar prototype molecules. Owing to their unique V-shapes, the nonlinear anisotropy values are found to be 0.63, 0.34, and 0.44 for compounds 1–3, respectively, which show the significant two-dimensional character of these compounds. Thus, the NLO amplitudes as well as the nonlinear anisotropies indicate that the above-entitled compounds are good contenders for optical and NLO applications.

scholarly journals From Oligo(Phenyleneethynylene) Monomers to Supramolecular Helices: The Role of Intermolecular Interactions in Aggregation

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3530
Author(s):  
Berta Fernández ◽  
Zulema Fernández ◽  
Emilio Quiñoá ◽  
Félix Freire
Keyword(s):  
Density Functional Theory ◽  
Self Assembly ◽  
Density Functional ◽  
Point Of View ◽  
Basis Set ◽  
Theoretical Point ◽  
Functional Theory ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Supramolecular helices that arise from the self-assembly of small organic molecules via non-covalent interactions play an important role in the structure and properties of the corresponding materials. Here we study the supramolecular helical aggregation of oligo(phenyleneethynylene) monomers from a theoretical point of view, always guiding the studies with experimentally available data. In this way, by systematically increasing the number of monomer units, optimized n-mer geometries are obtained along with the corresponding absorption and circular dichroism spectra. For the geometry optimizations we use density functional theory together with the B3LYP-D3 functional and the 6–31G** basis set. For obtaining the spectra we resort to time-dependent density functional theory using the CAM-B3LYP functional and the 3–21G basis set. These combinations of density functional and basis set were selected after systematic convergence studies. The theoretical results are analyzed and compared to the experimentally available spectra, observing a good agreement.

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

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4117 ◽  
Author(s):  
Ilya Nifant’ev ◽  
Pavel Ivchenko
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Transition States ◽  
Ring Opening Polymerization ◽  
Molecular Structures ◽  
Data Sets ◽  
Dft Methods ◽  
Cyclic Esters ◽  
Dft Modeling ◽  
The Difference

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.

Theoretical investigation of the derivatives of favipiravir (T-705) as potential drugs for Ebola virus

2018 ◽  
Vol 3 (9) ◽  
Author(s):  
Lydia Rhyman ◽  
Mahir Tursun ◽  
Hassan H. Abdallah ◽  
Yee Siew Choong ◽  
Cemal Parlak ◽  
...  
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Ebola Virus ◽  
Dft Method ◽  
Basis Set ◽  
Functional Theory ◽  
Experimental Parameters ◽  
Good Comparison ◽  
Free Energy Of Binding ◽  
Derivatives Of

Abstract Density functional theory (DFT) method was used to compute the structural and vibrational parameters of favipiravir (T-705) in the gas phase. The functional used was B3LYP in conjuction with the 6–311++G(d,p) basis set. We also computed these parameters for unsubstituted T-705 and derivatives of T-705 by substituting fluorine by chlorine, bromine and the cyanide group. There is a good comparison between the computed and experimental parameters for T-705 and therefore, the predicted data should be reliable for the other compounds for which experimental data is not available. We extended our DFT study to include molecular docking involving the Ebola virus viral protein 35 (VP35). The docking results indicate that the T-705 and its chlorine and bromine analogues have comparable free energy of binding with VP35. Graphical Abstract:

scholarly journals Density functional theoretical studies on the ring-opening polymerization mechanism of oxetane cation series compounds

RSC Advances ◽  
2017 ◽  
Vol 7 (78) ◽  
pp. 49626-49632
Author(s):  
Hai-Xia Wang ◽  
Min Pu ◽  
Yu-Cheng Ding
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Ring Opening ◽  
Density Functional ◽  
Ring Opening Polymerization ◽  
Basis Set ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Polymerization Mechanism

The mechanism of ring-opening polymerization of oxetane cation series compounds was investigated using the B3LYP and MP2 methods of density functional theory andab initiomethods, at the basis set levels of 6-31G(d,p) and 6-311++G(d,p).

Sign in / Sign up

Export Citation Format

Share Document