Electrostatics for Exploring the Nature of the Hydrogen Bonding in Polyethylene Oxide Hydration

Abstract

Binding between water and models of poly(ethylene oxide), (CH 2 -CH 2 -O) n , n ) 2-40, has been studied using the topographic features of the electrostatic potential, V(r), and standard density functional theory methods. It was found that, in general, the contour around the minima of the oxygen atoms overlap forming a negativevalued spiral coiled around a positive-valued helix. The positive zone defines a helical groove in the O-C-C-O units where minima lone pairs critical points are located. Topological analysis of the water molecule has also suggested that the attractive electrostatic effect between the positive water O-H zone and the negative PEO lone pairs plays an important role in the hydrogen bonding of the PEO-water system. Thus, the V(r) topology predicts a coil of water molecules around the PEO chain forming hydrogen bonding with two sites of ether oxygens. This coil is formed in such a way that more water molecules accumulate on the cavities surrounding the poly(ethylene oxide)'s oxygen atoms where the minima of the negative zone are located.

Growth of solid conical structures during multistage drying of sessile poly(ethylene oxide) droplets

“…Firstly, our data for the temporal evolution of A/A 0 presented in Fig.3 show, for all concentrations, a noticeable increase in surface area during the growth phase, even within our significant uncertainties. Secondly, PEO is known to crystallise into spherulites at high concentrations 17 , rather than form an amorphous glass. Thirdly, a glassy skin covering the droplet would prevent the growing deposits from falling over during drying, in contradiction with what is seen in our "failed" experiments.…”

Studies on the coordination chemistry of methylated xanthines and their imidazolium salts. Part 1: benzyl derivatives

“…of unique data, [46,47] and electrostatic potential topology [40][41][42]48]. DMol 3 program [49,50] was used to calculate q(r) and V(r).…”

“…Theoretical studies on theophylline (1), theobromine (2) and caffeine (3) Nature of active sites can be particularly explored using the electrostatic potential, V(r), which let us directly to determine where the electron-rich sites in a molecule or crystal are localized [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. For the region nearest to the nucleus, V N dominates and V(r) has similar topology to the electron density [43,44], q(r).…”

An Attempt to Construct an Isosurface Having Symmetry Elements

“…The most promising method to draw isosurfaces has been reported as "marching cubes algorithm" [12]. Although the usefulness of the above algorithm has been established by many websites [13][14][15] and original papers [11,12,16], another method for the drawing of an isosurface of an atomic orbital is pursued in this paper with a novel attempt to use symmetry operations.…”

“…Isosurfaces are displayed by computer graphics, and are used as visualization methods in many fields of chemistry. Orbital wavefunction, probability density, electron density and electrostatic potential have been visualized as isosurfaces [1][2][3][4][5][6][7][8][9][10][11]. The most promising method to draw isosurfaces has been reported as "marching cubes algorithm" [12].…”