Rapid Prediction of the Hydrogen Bond Cooperativity in N-methylacetamide Chains

✍ Scribed by Xiao-Nan Jiang; Chang-Sheng Wang

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 239 KB
• Volume: 10
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.200900591

✦ Synopsis

Abstract

A method is proposed to rapidly predict the hydrogen bond cooperativity in N__‐methylacetamide chains. The parameters needed are obtained from the fittings to the hydrogen bonding energies in the formamide chains containing 2 to 8 monomeric units. The scheme is then used to calculate the individual hydrogen bonding energies in__ N__‐methylacetamide chains containing 2 to 7 monomeric units. The cooperativity predicted is in good agreement with those obtained from MP2/6‐31+G** calculations by including the BSSE correction. Our scheme is further employed to predict the individual hydrogen bonding energies in larger__ N__‐methylacetamide chains containing up to 200 monomeric__ N__‐methylacetamide units, to which the MP2 method cannot be applied. Based on our scheme, a cooperative effect of over 170 % of the dimer hydrogen bonding energy in long__ N__‐methylacetamide chains is predicted. The method is also applied to heterogeneous chains containing formamide, acetamide,__ N__‐methylformamide, and__ N__‐methylacetamide. The individual hydrogen bonding energies in these heterogeneous chains are also in good agreement with those obtained from MP2 calculations with the BSSE correction, further demonstrating that our method is reasonable.__