PROBING THE CONFORMATIONAL LANDSCAPE OF 3-INDOLE ACETIC ACID: FLEXIBILITY OF THE SIDE $CHAIN.^{a}$

Abstract

3-indole acetic acid (IAA) is an ideal candidate to serve as a simple model to study the flexibility of the side chain as the spatial orientation of the acetic acid group is a function of three dihedral angles. To this end, the rotationally resolved $S_{1} \leftarrow S_{0}$ excitation spectra of the three origin bands of IAA were recorded and analyzed. The results indicate three distinct conformers with an in-plane side chain present in band A and out-of-plane orientations in bands B and C. The detailed structure of the conformational landscape will be discussed.