Intermolecular hydrogen bond in [ 2-(2-methyl-1H-indol-3-yl)acetic acid] dimer, DFT and NBO studies

In this research the structure of [2-(2-methyl-1H-indol-3-yl) acetic acid] and its dimer havebeen investigated by quantum mechanics approach. Indol-3-ylacetic acid (IAA) regulatesphysiological functions such as cell divisions and enlargement, developmental diversity, and thesynthesis of special proteins in plants [l]. X-ray diffraction analysis shows no explicit structuralfeatures to be blamed for the decrease in IAA (auxin) activity caused by attaching a 2-alkylsubstituent to the IAA molecule [2]. The carboxyl group adopts the synplanar motif and themolecules dimerize with O-H…O hydrogen bonds across the centers of symmetry [3].Theintermoleclar hydrogen bonding, particularly of the carboxyl group, which is one of thebiologically active ligand sites, has been studied by density functional theory. To investigate thenature of the hydrogen bond in the target molecule , the Wiberg bond orders [4], and secondorder perturbation energies (E2) have been calculated at the B3LYP/6-311++G** using NBO 5.0program. Natural bond orbital analysis confirms two O-H…O hydrogen bonds that are nearlysymmetric.

کلیدواژه ها:

2-Methylindole-3-Acetic Acid ، IAA ، Auxin ، DFT ، NBO ، Hydrogen Bond