Computational Evaluation of Intermolecular Interaction in Poly(Styrene-Maleic Acid)-Water Complexes Using Density Functional Theory

Abstract

The high application of Poly(styrene-maleic acid) (PSMA) in an aqueous environment, such as biomedical purposes, makes the interaction between PSMA and water molecules interesting to be investigated. This study evaluated the conformation, the hydrogen bond network, and the stabilities of all the possible intermolecular interactions between PSMA with water (PSMA−(H2O)n, n = 1–5). All calculations were executed using the density functional theory (DFT) method at B3LYP functional and the 6–311G** basis set. The energy interaction of PSMA–(H2O)5 complex was –56.66 kcal/mol, which is classified as high hydrogen bond interaction. The Highest Occupied Molecular Orbital (HOMO) – Lowest Unoccupied Molecular Orbital (LUMO) energy gap decreased with the rise in the number of H2O molecules, representing a more reactive complex. The strongest hydrogen bonding in PSMA–(H2O)5 wasformed through the interaction on O72···O17–H49 with stabilizing energy of 50.32 kcal/mol, that analyzed by natural bond orbital (NBO) theory. The quantum theory atoms in molecules (QTAIM) analysis showed that the hydrogen bonding (EHB) value on O72···O17–H49 was –14.95 kcal/mol. All computational data revealed that PSMA had moderate to high interaction with water molecules that indicated the water molecules were easily transported and kept in the PSMA matrix.

Quantum Chemical Calculation for Intermolecular Interactions of Alginate Dimer-Water Molecules

“…The optimized structures of alginic acid (Alg) and sodium alginate (SA) are presented in Figure 1 . Dimer Alg and SA structure were chosen to represent the polymer due to the fact that the interaction energy and enthalpies between dimers, trimers, and oligomers with water are almost similar [ 24 , 25 , 26 , 27 ]. Researchers also used dimer structures to evaluate the polymer [ 24 , 26 , 28 , 29 ].…”

“…Dimer Alg and SA structure were chosen to represent the polymer due to the fact that the interaction energy and enthalpies between dimers, trimers, and oligomers with water are almost similar [ 24 , 25 , 26 , 27 ]. Researchers also used dimer structures to evaluate the polymer [ 24 , 26 , 28 , 29 ]. G blocks (GG) of the alginate structure are stiffer compared to alternate blocks (GM) and M blocks (MM) due to their diaxial connection, and hence, they are more soluble at lower pH [ 16 , 30 ].…”

“…All calculations in this study were fulfilled by the density functional theory (DFT-D3) method using the hybrid of Becke’s three-parameter Lee, Yang, and Parr (B3LYP) functional and the basis set 6-31++G** [ 24 , 26 ]. A solvation model based on density (SMD) was used to calculate the effect of the water as a solvent [ 26 , 50 ].…”

Revealing the incorporation of an NH2group into the edge of carbon dots for H2O2sensingviathe C–N⋯H hydrogen bond interaction

“…7 help one identify the strength of interaction of the corresponding non-covalently interacting molecules. 125,126 For all the complex molecules, the NCI-RDG analysis reveals three kinds of weak intramolecular interactions. Firstly, a red (rice grain-shaped) isosurface is present in the center of the benzene rings, attributed to steric repulsive interactions and caused by the six carbon atoms of the rings in the Cdots, which corresponds to the spikes at 0.01 and 0.02 a.u.…”