Ab initio and DFT study on molecular structure, reactivity indices and nonlinear properties of 4-(4-aminophenylethynyl)picolinic acid and 4-(3-aminophenylethynyl)picolinic acid

Abstract

Ab initio and density functional theory methods were used to study chemical shifts and global reactivity index of 4-(4-aminophenylethynyl)picolinic acid and 4-(3-aminophenylethynyl)picolinic acid. The calculated chemical shifts for the two molecules correlated to the experimental data. The regression factor (R2) for chemical shifts calculated at HF/6-31G* and B3LYP/6-31G* were 0.940 and 0.964 for 4APPA and 0.929 and 0.953 for 3APPA respectively. The absorption maxima for 4APPA were 302.81 and 341.52 nm and 292.12 and 346.95 nm for 3APPA. Global reactivity indexes (hardness, chemical potential and nucleophilicity) revealed that 4APPA should be a better nucleophile than 3AAPA. The first hyperpolarizability calculated for 4APPA and 3APPA were 8.84x10-30 and 3.41x10-30esu respectively.