Molecular Dynamics Simulations Of β-CD Enantioseparation,Al/NiO Thermite Reaction And Adsorption Ofcalcium Ions On Cellulose

As a rapidly evolved research method,molecular dynamics simulation(MD)has the function of explaining experimental phenomena and elucidating reaction mechanisms.In this paper,MD is used as the research method based on Amber,Charmm and Reax FF force field to conduct a series of studies in the fields of β-cyclodextrins/terbutaline(β-CD/TB)enantioseparation mechanism,femtosecond laser-induced Al/Ni O thermite reaction and cellulose-calcium ions binding mechanism.The research result is as follows:1.Investigating the enantioseparation mechanism of β-CD and heptakis(2,3-di-O-actyl)-β-CD(HAD-β-CD)towards TB based on experimental data using a molecular dynamics/quantum mechanics/continuous solvent model(MD/QM/CSM)approach.The calculated results indicate the TB guest molecule enters the HDA-β-CD cavity from the benzene ring end,which solves the experimental problem of uncertain orientation of TB in the HDA-β-CD cavity.R-TB is compactly included by HAD-β-CD,as indicated by the computed binding affinity,this tight binding mode enhances the host–guest hydrophobic interaction and renders the R-complex significantly more stable than the S-complex.In contrast,the binding modes of R-and S-TB with β-CD are similar due to the poor flexibility of the host,which jeopardizes its ability to differentiate R-and S-TB.The calculated results are consistent with the experiments,and effectively supplement and explain the experimental phenomena.2.MD based on Reax FF method is performed to investigate the effect of different energy femtosecond laser-induced Al/Ni O thermite reaction.The calculated results suggest that the critical temperature for the occurrence of the thermite reaction of this system is between 510 K and 580 K.As the initial reaction temperature increases,the delay time of the thermite reaction decreases.The mean square displacement(MSD)indicates that the thermite reaction occurs based on a diffusion mechanism,which is consistent with the experimental results.3.Adsorption mechanism of calcium ions on cellulose is suggested based on MD method.The calculated results shows that cellulose in aqueous solution aggregate and entangle with each other,This results in enhanced interaction between calcium ions and hydroxyl oxygen atoms in cellulose chains and as a consequence,the calcium ions are adsorbed on cellulose.This adsorption mechanism provides a more reasonable explanation for the experimental phenomenon that calcium ions can form initial nuclei on cellulose units.