Intermolecular hydrogen bond interactions in N -carboxymethyl chitosan and n H2O: DFT and NBO studies

Membrane is the most important component in Proton Exchange Membrane Fuel Cell (PEMFC) which is widely developed in recent years. One of the membranes used in the PEMFCs is N-carboxymethyl chitosan. The aim of this research is to identify the possibility of intermolecular hydrogen bond interactions in N-carboxymethyl chitosan and nH<inf>2</inf>O (n=1-5) by using density functional theory to perform all the calculations. In this letter, we report all the possibility of hydrogen bond interactions by analyzing natural bond orbital to measure the relative strength of the hydrogen bonding interactions and the charge transfer of n-Ï from O-H. Interaction of N-carboxymethyl chitosan and 5H<inf>2</inf>O was found to be the strongest hydrogen bond among others with a stabilization energy of 56.93 kcal/mol. The value of stabilization energy was confirmed using molecular orbital calculation. Hydrogen bond interaction was predicted influenced by existing of the carboxylic group. © 2020 Elsevier B.V., All rights reserved.