scholarly journals Structural Changes in Block Copolymers: Coupling of Electric Field and Mobile Ions

2003 ◽  
Vol 90 (14) ◽  
Author(s):  
Yoav Tsori ◽  
François Tournilhac ◽  
David Andelman ◽  
Ludwik Leibler
Keyword(s):  
Block Copolymers ◽  
Electric Field ◽  
Structural Changes ◽  
Mobile Ions

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

2019 ◽  
Author(s):  
Johannes P. Dürholt ◽  
Babak Farhadi Jahromi ◽  
Rochus Schmid
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Changes ◽  
Dielectric Behavior ◽  
Two Dimensions ◽  
Dielectric Constants ◽  
Electric Response ◽  
Dipole Strength ◽  
Metal Organic ◽  
Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

scholarly journals Origin of the enhanced structural and reorientational relaxation rates in the presence of relatively weak dc electric fields

2004 ◽  
Vol 76 (1) ◽  
pp. 215-221 ◽  
Author(s):  
A. Vegiri
Keyword(s):  
Molecular Dynamics ◽  
Electric Field ◽  
Electric Fields ◽  
Structural Relaxation ◽  
Structural Changes ◽  
Common Mechanism ◽  
Weak Electric Field ◽  
Water Molecules ◽  
Relaxation Rates ◽  
Dynamics Simulations

The origin of the dramatic increase of the reorientational and structural relaxation rates of single water molecules in clusters of size N = 16, 32, and 64 at T = 200 K, under the influence of an external, relatively weak electric field (~0.5 107 V/cm) is examined through molecular dynamics simulations. The observed effect is attributed not to any profound structural changes, but to the increase of the size of the molecular cage. The response of water to an electric field in this range shows many similarities with the dynamics of water under low pressure. By referring to simulations and experiments from the literature, we show that in both cases the observed effects are dictated by a common mechanism.

scholarly journals Orienting Thin Films of Lamellar Block Copolymer: The Combined Effect of Mobile Ions and Electric Field

2018 ◽  
Vol 51 (19) ◽  
pp. 7881-7892
Author(s):  
Bin Zheng ◽  
Xingkun Man ◽  
Zhong-Can Ou-Yang ◽  
M. Schick ◽  
David Andelman
Keyword(s):  
Thin Films ◽  
Block Copolymer ◽  
Electric Field ◽  
Combined Effect ◽  
Mobile Ions

Simulations of Electric Field Induced Lamellar Alignment in Block Copolymers in the Presence of Selective Electrodes

2003 ◽  
Vol 12 (7) ◽  
pp. 508-511 ◽  
Author(s):  
A. V. Kyrylyuk ◽  
G. J. A. Sevink ◽  
A. V. Zvelindovsky ◽  
J. G. E. M. Fraaije
Keyword(s):  
Block Copolymers ◽  
Electric Field

scholarly journals A Preorganized Electric Field Leads to Minimal Geometrical Reorientation in the Catalytic Reaction of Ketosteroid Isomerase

2020 ◽  
Author(s):  
Yufan Wu ◽  
Stephen Fried ◽  
Steven Boxer
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Ground State ◽  
Active Site ◽  
Electrostatic Interactions ◽  
Stark Effect ◽  
Structural Changes ◽  
Enzymatic Catalysis ◽  
Ketosteroid Isomerase ◽  
Computational Enzyme Design

<div><p>Electrostatic interactions play a pivotal role in enzymatic catalysis and are increasingly modeled explicitly in computational enzyme design; nevertheless, they are challenging to measure experimentally. Using vibrational Stark effect (VSE) spectroscopy, we have measured electric fields inside the active site of the enzyme ketosteroid isomerase (KSI). These studies have shown that these fields can be unusually large, but it has been unclear to what extent they specifically stabilize the transition state (TS) relative to a ground state (GS). In the following, we use crystallography and computational modeling to show that KSI’s intrinsic electric field is nearly perfectly oriented to stabilize the geometry of its reaction’s TS. Moreover, we find that this electric field adjusts the orientation of its substrate in the ground state so that the substrate needs to only undergo minimal structural changes upon activation to its TS. This work provides evidence that the active site electric field in KSI is preorganized to facilitate catalysis and provides a template for how electrostatic preorganization can be measured in enzymatic systems. <br></p></div>

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