Spectroscopic and density functional theory studies of 7-hydroxy-3′-methoxyisoflavone: A new isoflavone from the seeds of Indigofera heterantha (Wall)

•A new isoflavone; 7-hydroxy-3′-methoxyisoflavone was isolated.•First comparative theoretical and experimental study on Isoflavone.•Experimental and theoretical IR, UV and NMR show excellent correlation.•IA, EA, EN and HOMO–LUMO gap were estimated at B3LYP/6-311G(d,p) level of theory.

A new isoflavone 7-hydroxy 3′-methoxyisoflavone (1) is isolated from the seeds of Indigofera heterantha. The structure of this new compound was established using spectroscopic techniques such as ID, 2D NMR, and mass spectrometry. Density functional theory calculations are carried out for the first time for geometric, electronic and spectroscopic properties of 1 (isoflavone). DFT calculations have been performed at B3LYP/6-311G(d,p) level of theory for obtaining geometric and spectroscopic properties of compound 1. The simulated vibrational spectrum of compound 1 at B3LYP/6-311G(d,p) shows nice correlation with the experimental IR spectrum after a scaling factor of 0.973. 1H and 13C NMR chemical shifts were calculated using Cramer’s re-parameterized function WP04 at 6-311G(d,p) basis set, and show nice correlation with the experimental data. Four conformers were considered for NMR chemical shift calculations. Electronic properties such as band gap, Ionization potential and electron affinities were also simulated for the first time; however, no comparison could be made with the experiment.

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