Rotationally resolved UV spectroscopy of the rotamers of indole-4-carboxylic acid: Evidence for charge transfer quenching.

ABSTRACT: Rotationally resolved electronic spectra of two conformational isomers of jet-cooled indole-4-carboxylic acid (I4CA) and the deuterated forms of the acid (-COOD) and amide (-ND) groups have been obtained using a UV laser/molecular beam spectrometer. The in-plane orientation of the acid group defines the two lowest energy rotamers of I4CA. The S₁ ← S₀ origin bands of the two rotamers and four isotopologues have been fit to asymmetric rotor Hamiltonians in both electronic states. From the best-fit parameters, the positions of the H-atoms in the principal axis frames of each conformer have been determined and serve to unambiguously identify the syn forms (i.e., COH⋯O) of the cis and trans rotamers. The experimental S₀ and S₁ inertial parameters, hyd

SUBMITTER: Yi JT 

PROVIDER: S-EPMC8230874 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature